Bump version numbers for 1.3.8 release.

Remove jar signatures to avoid SecurityException when repacking headless jar

See merge request briar/briar!1532

.gitlab-ci.yml

@@ -33,7 +33,7 @@ test:
   stage: test
   script:
     - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom animalSnifferMain animalSnifferTest
-    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom check
+    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom compileOfficialDebugAndroidTestSources compileScreenshotDebugAndroidTestSources check
   rules:
     - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
       when: always

.idea/codeStyles/Project.xml

@@ -31,15 +31,6 @@
       <option name="PACKAGES_TO_USE_STAR_IMPORTS">
         <value />
       </option>
-      <option name="PACKAGES_IMPORT_LAYOUT">
-        <value>
-          <package name="" alias="false" withSubpackages="true" />
-          <package name="java" alias="false" withSubpackages="true" />
-          <package name="javax" alias="false" withSubpackages="true" />
-          <package name="kotlin" alias="false" withSubpackages="true" />
-          <package name="" alias="true" withSubpackages="true" />
-        </value>
-      </option>
       <option name="NAME_COUNT_TO_USE_STAR_IMPORT" value="2147483647" />
       <option name="NAME_COUNT_TO_USE_STAR_IMPORT_FOR_MEMBERS" value="2147483647" />
       <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
@@ -197,9 +188,9 @@
     </codeStyleSettings>
     <codeStyleSettings language="kotlin">
       <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
-      <option name="PARAMETER_ANNOTATION_WRAP" value="1" />
+      <indentOptions>
-      <option name="VARIABLE_ANNOTATION_WRAP" value="1" />
+        <option name="CONTINUATION_INDENT_SIZE" value="4" />
-      <option name="ENUM_CONSTANTS_WRAP" value="1" />
+      </indentOptions>
     </codeStyleSettings>
   </code_scheme>
 </component>

README.md

@@ -1 +1,28 @@
-Briar is a messaging app designed for activists, journalists, and anyone else who needs a safe, easy and robust way to communicate. Unlike traditional messaging tools such as email, Twitter or Telegram, Briar doesn't rely on a central server - messages are synchronized directly between the users' devices. If the Internet's down, Briar can sync via Bluetooth or Wi-Fi, keeping the information flowing in a crisis. If the Internet's up, Briar can sync via the Tor network, protecting users and their relationships from surveillance.
+# Briar
+Briar is a messaging app designed for activists, journalists, and anyone else who needs a safe, easy and robust way to communicate.
+
+Unlike traditional messaging tools such as email, Twitter or Telegram, Briar doesn't rely on a central server - messages are synchronized directly between the users' devices. 
+
+If the Internet's down, Briar can sync via Bluetooth or Wi-Fi, keeping information flowing in a crisis. If the Internet's up, Briar can sync via the Tor network, protecting users and their relationships from surveillance.
+
+## Download Briar
+
+[<img src="https://briarproject.org//img/fdroid_badge.png"  width="240">](https://briarproject.org/fdroid)
+[<img src="https://briarproject.org/img/google_play_badge_web_generic.png"  width="240">](https://play.google.com/store/apps/details?id=org.briarproject.briar.android)
+
+You can also [download the APK file](https://briarproject.org/apk) directly from
+our site.
+
+## Useful links
+[briarproject.org](https://briarproject.org/)
+
+[Source code](https://code.briarproject.org/briar/briar/tree/master)
+
+[Manual](https://briarproject.org/manual/)
+
+[Wiki](https://code.briarproject.org/briar/briar/-/wikis/home)
+
+## Donate
+
+[![Donate using Liberapay](https://briarproject.org/img/liberapay.svg)](https://liberapay.com/Briar/donate) [![Flattr this](https://briarproject.org/img/flattr-badge-large.png "Flattr this")](https://flattr.com/t/592836/)   
+Bitcoin and BCH: 1NZCKkUCtJV2U2Y9hDb9uq8S7ksFCFGR6K

bramble-android/build.gradle

@@ -15,8 +15,8 @@ android {
 	defaultConfig {
 		minSdkVersion 16
 		targetSdkVersion 30
-		versionCode 10305
+		versionCode 10308
-		versionName "1.3.5"
+		versionName "1.3.8"
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"

bramble-android/src/main/java/org/briarproject/bramble/plugin/file/AndroidRemovableDrivePluginFactory.java

@@ -20,7 +20,7 @@ import static org.briarproject.bramble.api.plugin.file.RemovableDriveConstants.I
 public class AndroidRemovableDrivePluginFactory implements
 		SimplexPluginFactory {
 
-	private static final int MAX_LATENCY = (int) DAYS.toMillis(14);
+	private static final long MAX_LATENCY = DAYS.toMillis(28);
 
 	private final Application app;
 

bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPlugin.java

@@ -29,6 +29,7 @@ import java.net.UnknownHostException;
 import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
+import java.util.regex.Pattern;
 
 import javax.annotation.Nullable;
 import javax.net.SocketFactory;
@@ -48,6 +49,7 @@ import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
 import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
 import static org.briarproject.bramble.util.IoUtils.tryToClose;
 import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.NetworkUtils.getNetworkInterfaces;
 
 @NotNullByDefault
 class AndroidLanTcpPlugin extends LanTcpPlugin {
@@ -55,6 +57,13 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 	private static final Logger LOG =
 			getLogger(AndroidLanTcpPlugin.class.getName());
 
+	/**
+	 * The interface name is used as a heuristic for deciding whether the
+	 * device is providing a wifi access point.
+	 */
+	private static final Pattern AP_INTERFACE_NAME =
+			Pattern.compile("^(wlan|ap|p2p)[-0-9]");
+
 	private final Executor connectionStatusExecutor;
 	private final ConnectivityManager connectivityManager;
 	@Nullable
@@ -130,17 +139,14 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 		if (info != null && info.getIpAddress() != 0) {
 			return new Pair<>(intToInetAddress(info.getIpAddress()), false);
 		}
-		List<InterfaceAddress> ifAddrs = getLocalInterfaceAddresses();
+		// If we're providing an access point, return its address
-		// If we're providing a normal access point, return its address
+		for (NetworkInterface iface : getNetworkInterfaces()) {
-		for (InterfaceAddress ifAddr : ifAddrs) {
+			if (AP_INTERFACE_NAME.matcher(iface.getName()).find()) {
-			if (isAndroidWifiApAddress(ifAddr)) {
+				for (InterfaceAddress ifAddr : iface.getInterfaceAddresses()) {
-				return new Pair<>(ifAddr.getAddress(), true);
+					if (isPossibleWifiApInterface(ifAddr)) {
-			}
+						return new Pair<>(ifAddr.getAddress(), true);
-		}
+					}
-		// If we're providing a wifi direct access point, return its address
+				}
-		for (InterfaceAddress ifAddr : ifAddrs) {
-			if (isAndroidWifiDirectApAddress(ifAddr)) {
-				return new Pair<>(ifAddr.getAddress(), true);
 			}
 		}
 		// Not connected to wifi
@@ -148,33 +154,18 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 	}
 
 	/**
-	 * Returns true if the given address belongs to a network provided by an
+	 * Returns true if the given address may belong to an interface providing
-	 * Android access point (including the access point's own address).
+	 * a wifi access point (including wifi direct legacy mode access points).
 	 * <p>
-	 * The access point's address is usually 192.168.43.1, but at least one
+	 * This method may return true for wifi client interfaces as well, but
-	 * device (Honor 8A) may use other addresses in the range 192.168.43.0/24.
+	 * we've already checked for a wifi client connection above.
 	 */
-	private boolean isAndroidWifiApAddress(InterfaceAddress ifAddr) {
+	private boolean isPossibleWifiApInterface(InterfaceAddress ifAddr) {
 		if (ifAddr.getNetworkPrefixLength() != 24) return false;
 		byte[] ip = ifAddr.getAddress().getAddress();
 		return ip.length == 4
 				&& ip[0] == (byte) 192
-				&& ip[1] == (byte) 168
+				&& ip[1] == (byte) 168;
-				&& ip[2] == (byte) 43;
-	}
-
-	/**
-	 * Returns true if the given address belongs to a network provided by an
-	 * Android wifi direct legacy mode access point (including the access
-	 * point's own address).
-	 */
-	private boolean isAndroidWifiDirectApAddress(InterfaceAddress ifAddr) {
-		if (ifAddr.getNetworkPrefixLength() != 24) return false;
-		byte[] ip = ifAddr.getAddress().getAddress();
-		return ip.length == 4
-				&& ip[0] == (byte) 192
-				&& ip[1] == (byte) 168
-				&& ip[2] == (byte) 49;
 	}
 
 	/**

bramble-api/src/main/java/org/briarproject/bramble/api/FeatureFlags.java

@@ -11,9 +11,7 @@ public interface FeatureFlags {
 
 	boolean shouldEnableDisappearingMessages();
 
-	boolean shouldEnableConnectViaBluetooth();
+	boolean shouldEnableTransferData();
 
 	boolean shouldEnableShareAppViaOfflineHotspot();
-
-	boolean shouldEnableTransferData();
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/file/RemovableDriveTask.java

@@ -14,9 +14,9 @@ public interface RemovableDriveTask extends Runnable {
 	TransportProperties getTransportProperties();
 
 	/**
-	 * Adds an observer to the task. The observer will be notified of state
+	 * Adds an observer to the task. The observer will be notified on the
-	 * changes on the event thread. If the task has already finished, the
+	 * event thread of the current state of the task and any subsequent state
-	 * observer will be notified of its final state.
+	 * changes.
 	 */
 	void addObserver(Consumer<State> observer);
 

bramble-api/src/main/java/org/briarproject/bramble/util/NetworkUtils.java

@@ -0,0 +1,34 @@
+package org.briarproject.bramble.util;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.net.NetworkInterface;
+import java.net.SocketException;
+import java.util.Enumeration;
+import java.util.List;
+import java.util.logging.Logger;
+
+import static java.util.Collections.emptyList;
+import static java.util.Collections.list;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@NotNullByDefault
+public class NetworkUtils {
+
+	private static final Logger LOG = getLogger(NetworkUtils.class.getName());
+
+	public static List<NetworkInterface> getNetworkInterfaces() {
+		try {
+			Enumeration<NetworkInterface> ifaces =
+					NetworkInterface.getNetworkInterfaces();
+			// Despite what the docs say, the return value can be null
+			//noinspection ConstantConditions
+			return ifaces == null ? emptyList() : list(ifaces);
+		} catch (SocketException e) {
+			logException(LOG, WARNING, e);
+			return emptyList();
+		}
+	}
+}

bramble-api/witness.gradle

@@ -10,8 +10,8 @@ dependencyVerification {
         'net.jcip:jcip-annotations:1.0:jcip-annotations-1.0.jar:be5805392060c71474bf6c9a67a099471274d30b83eef84bfc4e0889a4f1dcc0',
         'org.apache-extras.beanshell:bsh:2.0b6:bsh-2.0b6.jar:a17955976070c0573235ee662f2794a78082758b61accffce8d3f8aedcd91047',
         'org.codehaus.mojo.signature:java16:1.1:java16-1.1.signature:53799223a2c98dba2d0add810bed76315460df285c69e4f397ae6098f87dd619',
-        'org.codehaus.mojo:animal-sniffer-ant-tasks:1.16:animal-sniffer-ant-tasks-1.16.jar:890040976fbe2d584619a6a61b1fd2e925b3b5eb342a85eb2762c467c0d64e90',
+        'org.codehaus.mojo:animal-sniffer-ant-tasks:1.20:animal-sniffer-ant-tasks-1.20.jar:bb7d2498144118311d968bb08ff6fae3fc535fb1cb9cca8b8e9ea65b189422ac',
-        'org.codehaus.mojo:animal-sniffer:1.16:animal-sniffer-1.16.jar:72be8bcc226ba43b937c722a08a07852bfa1b11400089265d5df0ee7b38b1d52',
+        'org.codehaus.mojo:animal-sniffer:1.20:animal-sniffer-1.20.jar:80c422523c38db91260c6d78e5ee4b012862ab61cc55020c9e243dd7b5c62249',
         'org.hamcrest:hamcrest-core:2.1:hamcrest-core-2.1.jar:e09109e54a289d88506b9bfec987ddd199f4217c9464132668351b9a4f00bee9',
         'org.hamcrest:hamcrest-library:2.1:hamcrest-library-2.1.jar:b7e2b6895b3b679f0e47b6380fda391b225e9b78505db9d8bdde8d3cc8d52a21',
         'org.hamcrest:hamcrest:2.1:hamcrest-2.1.jar:ba93b2e3a562322ba432f0a1b53addcc55cb188253319a020ed77f824e692050',
@@ -21,7 +21,7 @@ dependencyVerification {
         'org.jmock:jmock-testjar:2.12.0:jmock-testjar-2.12.0.jar:efefbcf6cd294d0e29f0c46eb2a3380d4ca4e1763ff719c69e2f2ac62f564a04',
         'org.jmock:jmock:2.12.0:jmock-2.12.0.jar:266d07314c0cd343c46ff8a55601272de8cf406807caf55e6f313295f83d10be',
         'org.objenesis:objenesis:3.0.1:objenesis-3.0.1.jar:7a8ff780b9ff48415d7c705f60030b0acaa616e7f823c98eede3b63508d4e984',
-        'org.ow2.asm:asm-all:5.2:asm-all-5.2.jar:7fbffbc1db3422e2101689fd88df8384b15817b52b9b2b267b9f6d2511dc198d',
         'org.ow2.asm:asm:7.1:asm-7.1.jar:4ab2fa2b6d2cc9ccb1eaa05ea329c407b47b13ed2915f62f8c4b8cc96258d4de',
+        'org.ow2.asm:asm:9.1:asm-9.1.jar:cda4de455fab48ff0bcb7c48b4639447d4de859a7afc30a094a986f0936beba2',
     ]
 }

bramble-core/build.gradle

@@ -10,7 +10,7 @@ apply from: '../dagger.gradle'
 
 dependencies {
 	implementation project(path: ':bramble-api', configuration: 'default')
-	implementation 'com.madgag.spongycastle:core:1.58.0.0'
+	implementation 'org.bouncycastle:bcprov-jdk15on:1.69'
 	implementation 'com.h2database:h2:1.4.192' // The last version that supports Java 1.6
 	implementation 'org.bitlet:weupnp:0.1.4'
 	implementation 'net.i2p.crypto:eddsa:0.2.0'
@@ -32,6 +32,14 @@ dependencies {
 	signature 'org.codehaus.mojo.signature:java16:1.1@signature'
 }
 
+animalsniffer {
+	// Allow requireNonNull: Android desugaring rewrites it (so it's safe for us to use),
+	// and it gets used when passing method references instead of lambdas with Java 11.
+	// Note that this line allows *all* methods from java.util.Objects.
+	// That's the best that we can do with the configuration options that Animal Sniffer offers.
+	ignore 'java.util.Objects'
+}
+
 // needed to make test output available to bramble-java
 configurations {
 	testOutput.extendsFrom(testCompile)

bramble-core/src/main/java/org/briarproject/bramble/crypto/CryptoComponentImpl.java

@@ -4,6 +4,9 @@ import net.i2p.crypto.eddsa.EdDSAPrivateKey;
 import net.i2p.crypto.eddsa.EdDSAPublicKey;
 import net.i2p.crypto.eddsa.KeyPairGenerator;
 
+import org.bouncycastle.crypto.CryptoException;
+import org.bouncycastle.crypto.Digest;
+import org.bouncycastle.crypto.digests.Blake2bDigest;
 import org.briarproject.bramble.api.crypto.AgreementPrivateKey;
 import org.briarproject.bramble.api.crypto.AgreementPublicKey;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
@@ -20,9 +23,6 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.system.SecureRandomProvider;
 import org.briarproject.bramble.util.ByteUtils;
 import org.briarproject.bramble.util.StringUtils;
-import org.spongycastle.crypto.CryptoException;
-import org.spongycastle.crypto.Digest;
-import org.spongycastle.crypto.digests.Blake2bDigest;
 import org.whispersystems.curve25519.Curve25519;
 import org.whispersystems.curve25519.Curve25519KeyPair;
 

bramble-core/src/main/java/org/briarproject/bramble/crypto/MessageEncrypter.java

@@ -1,38 +1,38 @@
 package org.briarproject.bramble.crypto;
 
+import org.bouncycastle.asn1.teletrust.TeleTrusTNamedCurves;
+import org.bouncycastle.asn1.x9.X9ECParameters;
+import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
+import org.bouncycastle.crypto.BasicAgreement;
+import org.bouncycastle.crypto.BlockCipher;
+import org.bouncycastle.crypto.CipherParameters;
+import org.bouncycastle.crypto.CryptoException;
+import org.bouncycastle.crypto.DerivationFunction;
+import org.bouncycastle.crypto.KeyEncoder;
+import org.bouncycastle.crypto.Mac;
+import org.bouncycastle.crypto.agreement.ECDHCBasicAgreement;
+import org.bouncycastle.crypto.digests.SHA256Digest;
+import org.bouncycastle.crypto.engines.AESLightEngine;
+import org.bouncycastle.crypto.engines.IESEngine;
+import org.bouncycastle.crypto.generators.ECKeyPairGenerator;
+import org.bouncycastle.crypto.generators.EphemeralKeyPairGenerator;
+import org.bouncycastle.crypto.generators.KDF2BytesGenerator;
+import org.bouncycastle.crypto.macs.HMac;
+import org.bouncycastle.crypto.modes.CBCBlockCipher;
+import org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher;
+import org.bouncycastle.crypto.params.AsymmetricKeyParameter;
+import org.bouncycastle.crypto.params.ECDomainParameters;
+import org.bouncycastle.crypto.params.ECKeyGenerationParameters;
+import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
+import org.bouncycastle.crypto.params.ECPublicKeyParameters;
+import org.bouncycastle.crypto.params.IESWithCipherParameters;
+import org.bouncycastle.crypto.parsers.ECIESPublicKeyParser;
 import org.briarproject.bramble.api.crypto.KeyPair;
 import org.briarproject.bramble.api.crypto.KeyParser;
 import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.util.StringUtils;
-import org.spongycastle.asn1.teletrust.TeleTrusTNamedCurves;
-import org.spongycastle.asn1.x9.X9ECParameters;
-import org.spongycastle.crypto.AsymmetricCipherKeyPair;
-import org.spongycastle.crypto.BasicAgreement;
-import org.spongycastle.crypto.BlockCipher;
-import org.spongycastle.crypto.CipherParameters;
-import org.spongycastle.crypto.CryptoException;
-import org.spongycastle.crypto.DerivationFunction;
-import org.spongycastle.crypto.KeyEncoder;
-import org.spongycastle.crypto.Mac;
-import org.spongycastle.crypto.agreement.ECDHCBasicAgreement;
-import org.spongycastle.crypto.digests.SHA256Digest;
-import org.spongycastle.crypto.engines.AESLightEngine;
-import org.spongycastle.crypto.engines.IESEngine;
-import org.spongycastle.crypto.generators.ECKeyPairGenerator;
-import org.spongycastle.crypto.generators.EphemeralKeyPairGenerator;
-import org.spongycastle.crypto.generators.KDF2BytesGenerator;
-import org.spongycastle.crypto.macs.HMac;
-import org.spongycastle.crypto.modes.CBCBlockCipher;
-import org.spongycastle.crypto.paddings.PaddedBufferedBlockCipher;
-import org.spongycastle.crypto.params.AsymmetricKeyParameter;
-import org.spongycastle.crypto.params.ECDomainParameters;
-import org.spongycastle.crypto.params.ECKeyGenerationParameters;
-import org.spongycastle.crypto.params.ECPrivateKeyParameters;
-import org.spongycastle.crypto.params.ECPublicKeyParameters;
-import org.spongycastle.crypto.params.IESWithCipherParameters;
-import org.spongycastle.crypto.parsers.ECIESPublicKeyParser;
 
 import java.io.FileInputStream;
 import java.io.FileOutputStream;

bramble-core/src/main/java/org/briarproject/bramble/crypto/ScryptKdf.java

@@ -1,9 +1,9 @@
 package org.briarproject.bramble.crypto;
 
+import org.bouncycastle.crypto.generators.SCrypt;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.util.StringUtils;
-import org.spongycastle.crypto.generators.SCrypt;
 
 import java.util.logging.Logger;
 

bramble-core/src/main/java/org/briarproject/bramble/crypto/Sec1KeyParser.java

@@ -1,14 +1,14 @@
 package org.briarproject.bramble.crypto;
 
+import org.bouncycastle.crypto.params.ECDomainParameters;
+import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
+import org.bouncycastle.crypto.params.ECPublicKeyParameters;
+import org.bouncycastle.math.ec.ECCurve;
+import org.bouncycastle.math.ec.ECPoint;
 import org.briarproject.bramble.api.crypto.KeyParser;
 import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.spongycastle.crypto.params.ECDomainParameters;
-import org.spongycastle.crypto.params.ECPrivateKeyParameters;
-import org.spongycastle.crypto.params.ECPublicKeyParameters;
-import org.spongycastle.math.ec.ECCurve;
-import org.spongycastle.math.ec.ECPoint;
 
 import java.math.BigInteger;
 import java.security.GeneralSecurityException;

bramble-core/src/main/java/org/briarproject/bramble/crypto/Sec1PrivateKey.java

@@ -1,8 +1,8 @@
 package org.briarproject.bramble.crypto;
 
+import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
 import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.spongycastle.crypto.params.ECPrivateKeyParameters;
 
 import javax.annotation.concurrent.Immutable;
 

bramble-core/src/main/java/org/briarproject/bramble/crypto/Sec1PublicKey.java

@@ -1,8 +1,8 @@
 package org.briarproject.bramble.crypto;
 
+import org.bouncycastle.crypto.params.ECPublicKeyParameters;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.spongycastle.crypto.params.ECPublicKeyParameters;
 
 import javax.annotation.concurrent.Immutable;
 

bramble-core/src/main/java/org/briarproject/bramble/crypto/TransportCryptoImpl.java

@@ -1,5 +1,7 @@
 package org.briarproject.bramble.crypto;
 
+import org.bouncycastle.crypto.Digest;
+import org.bouncycastle.crypto.digests.Blake2bDigest;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.KeyPair;
 import org.briarproject.bramble.api.crypto.PublicKey;
@@ -9,8 +11,6 @@ import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.transport.IncomingKeys;
 import org.briarproject.bramble.api.transport.OutgoingKeys;
 import org.briarproject.bramble.api.transport.TransportKeys;
-import org.spongycastle.crypto.Digest;
-import org.spongycastle.crypto.digests.Blake2bDigest;
 
 import java.security.GeneralSecurityException;
 

bramble-core/src/main/java/org/briarproject/bramble/crypto/XSalsa20Poly1305AuthenticatedCipher.java

@@ -1,13 +1,13 @@
 package org.briarproject.bramble.crypto;
 
+import org.bouncycastle.crypto.DataLengthException;
+import org.bouncycastle.crypto.engines.XSalsa20Engine;
+import org.bouncycastle.crypto.generators.Poly1305KeyGenerator;
+import org.bouncycastle.crypto.macs.Poly1305;
+import org.bouncycastle.crypto.params.KeyParameter;
+import org.bouncycastle.crypto.params.ParametersWithIV;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.spongycastle.crypto.DataLengthException;
-import org.spongycastle.crypto.engines.XSalsa20Engine;
-import org.spongycastle.crypto.generators.Poly1305KeyGenerator;
-import org.spongycastle.crypto.macs.Poly1305;
-import org.spongycastle.crypto.params.KeyParameter;
-import org.spongycastle.crypto.params.ParametersWithIV;
 
 import java.security.GeneralSecurityException;
 

bramble-core/src/main/java/org/briarproject/bramble/db/JdbcDatabase.java

@@ -2331,7 +2331,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.setInt(2, DELIVERED.getValue());
 			rs = ps.executeQuery();
 			rs.next();
-			long total = rs.getInt(1);
+			long total = rs.getLong(1);
 			rs.close();
 			ps.close();
 			return total;

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/TcpPlugin.java

@@ -28,11 +28,9 @@ import java.net.InterfaceAddress;
 import java.net.NetworkInterface;
 import java.net.ServerSocket;
 import java.net.Socket;
-import java.net.SocketException;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Enumeration;
 import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -53,7 +51,7 @@ import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
 import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
 import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
 import static org.briarproject.bramble.util.IoUtils.tryToClose;
-import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.NetworkUtils.getNetworkInterfaces;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubSocketAddress;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 
@@ -98,7 +96,6 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 	/**
 	 * Returns true if connections to the given address can be attempted.
 	 */
-	@SuppressWarnings("BooleanMethodIsAlwaysInverted")
 	protected abstract boolean isConnectable(InterfaceAddress local,
 			InetSocketAddress remote);
 
@@ -398,17 +395,6 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 		return addrs;
 	}
 
-	private List<NetworkInterface> getNetworkInterfaces() {
-		try {
-			Enumeration<NetworkInterface> ifaces =
-					NetworkInterface.getNetworkInterfaces();
-			return ifaces == null ? emptyList() : list(ifaces);
-		} catch (SocketException e) {
-			logException(LOG, WARNING, e);
-			return emptyList();
-		}
-	}
-
 	@Override
 	public void eventOccurred(Event e) {
 		if (e instanceof SettingsUpdatedEvent) {

bramble-core/src/main/java/org/briarproject/bramble/plugin/tor/TorRendezvousCryptoImpl.java

@@ -4,10 +4,10 @@ import net.i2p.crypto.eddsa.spec.EdDSANamedCurveSpec;
 import net.i2p.crypto.eddsa.spec.EdDSANamedCurveTable;
 import net.i2p.crypto.eddsa.spec.EdDSAPrivateKeySpec;
 
+import org.bouncycastle.crypto.Digest;
+import org.bouncycastle.crypto.digests.SHA3Digest;
+import org.bouncycastle.util.encoders.Base64;
 import org.briarproject.bramble.util.Base32;
-import org.spongycastle.crypto.Digest;
-import org.spongycastle.crypto.digests.SHA3Digest;
-import org.spongycastle.util.encoders.Base64;
 
 import java.nio.charset.Charset;
 

bramble-core/src/main/java/org/briarproject/bramble/rendezvous/KeyMaterialSourceImpl.java

@@ -1,11 +1,11 @@
 package org.briarproject.bramble.rendezvous;
 
+import org.bouncycastle.crypto.engines.Salsa20Engine;
+import org.bouncycastle.crypto.params.KeyParameter;
+import org.bouncycastle.crypto.params.ParametersWithIV;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.rendezvous.KeyMaterialSource;
-import org.spongycastle.crypto.engines.Salsa20Engine;
-import org.spongycastle.crypto.params.KeyParameter;
-import org.spongycastle.crypto.params.ParametersWithIV;
 
 import javax.annotation.concurrent.GuardedBy;
 import javax.annotation.concurrent.ThreadSafe;

bramble-core/src/test/java/org/briarproject/bramble/crypto/Blake2bDigestTest.java

@@ -1,9 +1,9 @@
 package org.briarproject.bramble.crypto;
 
+import org.bouncycastle.crypto.digests.Blake2bDigest;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.util.StringUtils;
 import org.junit.Test;
-import org.spongycastle.crypto.digests.Blake2bDigest;
 
 import java.util.Random;
 

bramble-core/src/test/java/org/briarproject/bramble/crypto/EllipticCurveMultiplicationTest.java

@@ -1,115 +0,0 @@
-package org.briarproject.bramble.crypto;
-
-import org.briarproject.bramble.test.BrambleTestCase;
-import org.junit.Test;
-import org.spongycastle.asn1.teletrust.TeleTrusTNamedCurves;
-import org.spongycastle.asn1.x9.X9ECParameters;
-import org.spongycastle.crypto.AsymmetricCipherKeyPair;
-import org.spongycastle.crypto.agreement.ECDHCBasicAgreement;
-import org.spongycastle.crypto.generators.ECKeyPairGenerator;
-import org.spongycastle.crypto.params.ECDomainParameters;
-import org.spongycastle.crypto.params.ECKeyGenerationParameters;
-import org.spongycastle.crypto.params.ECPrivateKeyParameters;
-import org.spongycastle.crypto.params.ECPublicKeyParameters;
-import org.spongycastle.math.ec.ECCurve;
-import org.spongycastle.math.ec.ECPoint;
-import org.spongycastle.math.ec.MontgomeryLadderMultiplier;
-
-import java.math.BigInteger;
-import java.security.SecureRandom;
-
-import static org.junit.Assert.assertEquals;
-
-public class EllipticCurveMultiplicationTest extends BrambleTestCase {
-
-	@Test
-	public void testMultiplierProducesSameResultsAsDefault() throws Exception {
-		// Instantiate the default implementation of the curve
-		X9ECParameters defaultX9Parameters =
-				TeleTrusTNamedCurves.getByName("brainpoolp256r1");
-		ECCurve defaultCurve = defaultX9Parameters.getCurve();
-		ECPoint defaultG = defaultX9Parameters.getG();
-		BigInteger defaultN = defaultX9Parameters.getN();
-		BigInteger defaultH = defaultX9Parameters.getH();
-		ECDomainParameters defaultParameters = new ECDomainParameters(
-				defaultCurve, defaultG, defaultN, defaultH);
-		// Instantiate an implementation using the Montgomery ladder multiplier
-		ECDomainParameters montgomeryParameters =
-				constantTime(defaultParameters);
-		// Generate two key pairs with each set of parameters, using the same
-		// deterministic PRNG for both sets of parameters
-		byte[] seed = new byte[32];
-		new SecureRandom().nextBytes(seed);
-		// Montgomery ladder multiplier
-		SecureRandom random = new PseudoSecureRandom(seed);
-		ECKeyGenerationParameters montgomeryGeneratorParams =
-				new ECKeyGenerationParameters(montgomeryParameters, random);
-		ECKeyPairGenerator montgomeryGenerator = new ECKeyPairGenerator();
-		montgomeryGenerator.init(montgomeryGeneratorParams);
-		AsymmetricCipherKeyPair montgomeryKeyPair1 =
-				montgomeryGenerator.generateKeyPair();
-		ECPrivateKeyParameters montgomeryPrivate1 =
-				(ECPrivateKeyParameters) montgomeryKeyPair1.getPrivate();
-		ECPublicKeyParameters montgomeryPublic1 =
-				(ECPublicKeyParameters) montgomeryKeyPair1.getPublic();
-		AsymmetricCipherKeyPair montgomeryKeyPair2 =
-				montgomeryGenerator.generateKeyPair();
-		ECPrivateKeyParameters montgomeryPrivate2 =
-				(ECPrivateKeyParameters) montgomeryKeyPair2.getPrivate();
-		ECPublicKeyParameters montgomeryPublic2 =
-				(ECPublicKeyParameters) montgomeryKeyPair2.getPublic();
-		// Default multiplier
-		random = new PseudoSecureRandom(seed);
-		ECKeyGenerationParameters defaultGeneratorParams =
-				new ECKeyGenerationParameters(defaultParameters, random);
-		ECKeyPairGenerator defaultGenerator = new ECKeyPairGenerator();
-		defaultGenerator.init(defaultGeneratorParams);
-		AsymmetricCipherKeyPair defaultKeyPair1 =
-				defaultGenerator.generateKeyPair();
-		ECPrivateKeyParameters defaultPrivate1 =
-				(ECPrivateKeyParameters) defaultKeyPair1.getPrivate();
-		ECPublicKeyParameters defaultPublic1 =
-				(ECPublicKeyParameters) defaultKeyPair1.getPublic();
-		AsymmetricCipherKeyPair defaultKeyPair2 =
-				defaultGenerator.generateKeyPair();
-		ECPrivateKeyParameters defaultPrivate2 =
-				(ECPrivateKeyParameters) defaultKeyPair2.getPrivate();
-		ECPublicKeyParameters defaultPublic2 =
-				(ECPublicKeyParameters) defaultKeyPair2.getPublic();
-		// The key pairs generated with both sets of parameters should be equal
-		assertEquals(montgomeryPrivate1.getD(), defaultPrivate1.getD());
-		assertEquals(montgomeryPublic1.getQ(), defaultPublic1.getQ());
-		assertEquals(montgomeryPrivate2.getD(), defaultPrivate2.getD());
-		assertEquals(montgomeryPublic2.getQ(), defaultPublic2.getQ());
-		// OK, all of the above was just sanity checks - now for the test!
-		ECDHCBasicAgreement agreement = new ECDHCBasicAgreement();
-		agreement.init(montgomeryPrivate1);
-		BigInteger sharedSecretMontgomeryMontgomery =
-				agreement.calculateAgreement(montgomeryPublic2);
-		agreement.init(montgomeryPrivate1);
-		BigInteger sharedSecretMontgomeryDefault =
-				agreement.calculateAgreement(defaultPublic2);
-		agreement.init(defaultPrivate1);
-		BigInteger sharedSecretDefaultMontgomery =
-				agreement.calculateAgreement(montgomeryPublic2);
-		agreement.init(defaultPrivate1);
-		BigInteger sharedSecretDefaultDefault =
-				agreement.calculateAgreement(defaultPublic2);
-		// Shared secrets calculated with different multipliers should be equal
-		assertEquals(sharedSecretMontgomeryMontgomery,
-				sharedSecretMontgomeryDefault);
-		assertEquals(sharedSecretMontgomeryMontgomery,
-				sharedSecretDefaultMontgomery);
-		assertEquals(sharedSecretMontgomeryMontgomery,
-				sharedSecretDefaultDefault);
-	}
-
-	private static ECDomainParameters constantTime(ECDomainParameters in) {
-		ECCurve curve = in.getCurve().configure().setMultiplier(
-				new MontgomeryLadderMultiplier()).create();
-		BigInteger x = in.getG().getAffineXCoord().toBigInteger();
-		BigInteger y = in.getG().getAffineYCoord().toBigInteger();
-		ECPoint g = curve.createPoint(x, y);
-		return new ECDomainParameters(curve, g, in.getN(), in.getH());
-	}
-}

bramble-core/src/test/java/org/briarproject/bramble/crypto/EllipticCurvePerformanceTest.java

@@ -3,30 +3,26 @@ package org.briarproject.bramble.crypto;
 import net.i2p.crypto.eddsa.EdDSASecurityProvider;
 import net.i2p.crypto.eddsa.KeyPairGenerator;
 
-import org.spongycastle.asn1.sec.SECNamedCurves;
+import org.bouncycastle.asn1.sec.SECNamedCurves;
-import org.spongycastle.asn1.teletrust.TeleTrusTNamedCurves;
+import org.bouncycastle.asn1.teletrust.TeleTrusTNamedCurves;
-import org.spongycastle.asn1.x9.X9ECParameters;
+import org.bouncycastle.asn1.x9.X9ECParameters;
-import org.spongycastle.crypto.AsymmetricCipherKeyPair;
+import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
-import org.spongycastle.crypto.BasicAgreement;
+import org.bouncycastle.crypto.BasicAgreement;
-import org.spongycastle.crypto.Digest;
+import org.bouncycastle.crypto.Digest;
-import org.spongycastle.crypto.agreement.ECDHBasicAgreement;
+import org.bouncycastle.crypto.agreement.ECDHBasicAgreement;
-import org.spongycastle.crypto.agreement.ECDHCBasicAgreement;
+import org.bouncycastle.crypto.agreement.ECDHCBasicAgreement;
-import org.spongycastle.crypto.digests.Blake2bDigest;
+import org.bouncycastle.crypto.digests.Blake2bDigest;
-import org.spongycastle.crypto.generators.ECKeyPairGenerator;
+import org.bouncycastle.crypto.generators.ECKeyPairGenerator;
-import org.spongycastle.crypto.params.ECDomainParameters;
+import org.bouncycastle.crypto.params.ECDomainParameters;
-import org.spongycastle.crypto.params.ECKeyGenerationParameters;
+import org.bouncycastle.crypto.params.ECKeyGenerationParameters;
-import org.spongycastle.crypto.params.ParametersWithRandom;
+import org.bouncycastle.crypto.params.ParametersWithRandom;
-import org.spongycastle.crypto.signers.DSADigestSigner;
+import org.bouncycastle.crypto.signers.DSADigestSigner;
-import org.spongycastle.crypto.signers.DSAKCalculator;
+import org.bouncycastle.crypto.signers.DSAKCalculator;
-import org.spongycastle.crypto.signers.ECDSASigner;
+import org.bouncycastle.crypto.signers.ECDSASigner;
-import org.spongycastle.crypto.signers.HMacDSAKCalculator;
+import org.bouncycastle.crypto.signers.HMacDSAKCalculator;
-import org.spongycastle.math.ec.ECCurve;
-import org.spongycastle.math.ec.ECPoint;
-import org.spongycastle.math.ec.MontgomeryLadderMultiplier;
 import org.whispersystems.curve25519.Curve25519;
 import org.whispersystems.curve25519.Curve25519KeyPair;
 
-import java.math.BigInteger;
 import java.security.GeneralSecurityException;
 import java.security.KeyPair;
 import java.security.Provider;
@@ -55,14 +51,12 @@ public class EllipticCurvePerformanceTest {
 		for (String name : SEC_NAMES) {
 			ECDomainParameters params =
 					convertParams(SECNamedCurves.getByName(name));
-			runTest(name + " default", params);
+			runTest(name, params);
-			runTest(name + " constant", constantTime(params));
 		}
 		for (String name : BRAINPOOL_NAMES) {
 			ECDomainParameters params =
 					convertParams(TeleTrusTNamedCurves.getByName(name));
-			runTest(name + " default", params);
+			runTest(name, params);
-			runTest(name + " constant", constantTime(params));
 		}
 		runCurve25519Test();
 		runEd25519Test();
@@ -193,13 +187,4 @@ public class EllipticCurvePerformanceTest {
 		return new ECDomainParameters(in.getCurve(), in.getG(), in.getN(),
 				in.getH());
 	}
-
-	private static ECDomainParameters constantTime(ECDomainParameters in) {
-		ECCurve curve = in.getCurve().configure().setMultiplier(
-				new MontgomeryLadderMultiplier()).create();
-		BigInteger x = in.getG().getAffineXCoord().toBigInteger();
-		BigInteger y = in.getG().getAffineYCoord().toBigInteger();
-		ECPoint g = curve.createPoint(x, y);
-		return new ECDomainParameters(curve, g, in.getN(), in.getH());
-	}
 }

bramble-core/src/test/java/org/briarproject/bramble/crypto/MessageEncrypterTest.java

@@ -1,11 +1,11 @@
 package org.briarproject.bramble.crypto;
 
+import org.bouncycastle.crypto.CryptoException;
 import org.briarproject.bramble.api.crypto.KeyPair;
 import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.junit.Test;
-import org.spongycastle.crypto.CryptoException;
 
 import java.security.SecureRandom;
 

bramble-core/src/test/java/org/briarproject/bramble/crypto/PseudoRandom.java

@@ -1,11 +1,11 @@
 package org.briarproject.bramble.crypto;
 
+import org.bouncycastle.crypto.Digest;
+import org.bouncycastle.crypto.digests.Blake2bDigest;
+import org.bouncycastle.crypto.engines.Salsa20Engine;
+import org.bouncycastle.crypto.params.KeyParameter;
+import org.bouncycastle.crypto.params.ParametersWithIV;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.spongycastle.crypto.Digest;
-import org.spongycastle.crypto.digests.Blake2bDigest;
-import org.spongycastle.crypto.engines.Salsa20Engine;
-import org.spongycastle.crypto.params.KeyParameter;
-import org.spongycastle.crypto.params.ParametersWithIV;
 
 import javax.annotation.concurrent.NotThreadSafe;
 

bramble-core/src/test/java/org/briarproject/bramble/test/TestFeatureFlagModule.java

@@ -26,7 +26,7 @@ public class TestFeatureFlagModule {
 			}
 
 			@Override
-			public boolean shouldEnableConnectViaBluetooth() {
+			public boolean shouldEnableTransferData() {
 				return true;
 			}
 
@@ -34,11 +34,6 @@ public class TestFeatureFlagModule {
 			public boolean shouldEnableShareAppViaOfflineHotspot() {
 				return true;
 			}
-
-			@Override
-			public boolean shouldEnableTransferData() {
-				return true;
-			}
 		};
 	}
 }

bramble-core/witness.gradle

@@ -15,7 +15,6 @@ dependencyVerification {
         'com.google.guava:listenablefuture:9999.0-empty-to-avoid-conflict-with-guava:listenablefuture-9999.0-empty-to-avoid-conflict-with-guava.jar:b372a037d4230aa57fbeffdef30fd6123f9c0c2db85d0aced00c91b974f33f99',
         'com.google.j2objc:j2objc-annotations:1.1:j2objc-annotations-1.1.jar:2994a7eb78f2710bd3d3bfb639b2c94e219cedac0d4d084d516e78c16dddecf6',
         'com.h2database:h2:1.4.192:h2-1.4.192.jar:225b22e9857235c46c93861410b60b8c81c10dc8985f4faf188985ba5445126c',
-        'com.madgag.spongycastle:core:1.58.0.0:core-1.58.0.0.jar:199617dd5698c5a9312b898c0a4cec7ce9dd8649d07f65d91629f58229d72728',
         'com.squareup:javapoet:1.13.0:javapoet-1.13.0.jar:4c7517e848a71b36d069d12bb3bf46a70fd4cda3105d822b0ed2e19c00b69291',
         'javax.annotation:jsr250-api:1.0:jsr250-api-1.0.jar:a1a922d0d9b6d183ed3800dfac01d1e1eb159f0e8c6f94736931c1def54a941f',
         'javax.inject:javax.inject:1:javax.inject-1.jar:91c77044a50c481636c32d916fd89c9118a72195390452c81065080f957de7ff',
@@ -27,13 +26,14 @@ dependencyVerification {
         'net.ltgt.gradle.incap:incap:0.2:incap-0.2.jar:b625b9806b0f1e4bc7a2e3457119488de3cd57ea20feedd513db070a573a4ffd',
         'org.apache-extras.beanshell:bsh:2.0b6:bsh-2.0b6.jar:a17955976070c0573235ee662f2794a78082758b61accffce8d3f8aedcd91047',
         'org.bitlet:weupnp:0.1.4:weupnp-0.1.4.jar:88df7e6504929d00bdb832863761385c68ab92af945b04f0770b126270a444fb',
+        'org.bouncycastle:bcprov-jdk15on:1.69:bcprov-jdk15on-1.69.jar:e469bd39f936999f256002631003ff022a22951da9d5bd9789c7abfa9763a292',
         'org.briarproject:jtorctl:0.3:jtorctl-0.3.jar:f2939238a097898998432effe93b0334d97a787972ab3a91a8973a1d309fc864',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
         'org.codehaus.mojo.signature:java16:1.1:java16-1.1.signature:53799223a2c98dba2d0add810bed76315460df285c69e4f397ae6098f87dd619',
         'org.codehaus.mojo:animal-sniffer-annotations:1.17:animal-sniffer-annotations-1.17.jar:92654f493ecfec52082e76354f0ebf87648dc3d5cec2e3c3cdb947c016747a53',
-        'org.codehaus.mojo:animal-sniffer-ant-tasks:1.16:animal-sniffer-ant-tasks-1.16.jar:890040976fbe2d584619a6a61b1fd2e925b3b5eb342a85eb2762c467c0d64e90',
+        'org.codehaus.mojo:animal-sniffer-ant-tasks:1.20:animal-sniffer-ant-tasks-1.20.jar:bb7d2498144118311d968bb08ff6fae3fc535fb1cb9cca8b8e9ea65b189422ac',
-        'org.codehaus.mojo:animal-sniffer:1.16:animal-sniffer-1.16.jar:72be8bcc226ba43b937c722a08a07852bfa1b11400089265d5df0ee7b38b1d52',
+        'org.codehaus.mojo:animal-sniffer:1.20:animal-sniffer-1.20.jar:80c422523c38db91260c6d78e5ee4b012862ab61cc55020c9e243dd7b5c62249',
         'org.hamcrest:hamcrest-core:2.1:hamcrest-core-2.1.jar:e09109e54a289d88506b9bfec987ddd199f4217c9464132668351b9a4f00bee9',
         'org.hamcrest:hamcrest-library:2.1:hamcrest-library-2.1.jar:b7e2b6895b3b679f0e47b6380fda391b225e9b78505db9d8bdde8d3cc8d52a21',
         'org.hamcrest:hamcrest:2.1:hamcrest-2.1.jar:ba93b2e3a562322ba432f0a1b53addcc55cb188253319a020ed77f824e692050',
@@ -48,8 +48,8 @@ dependencyVerification {
         'org.jmock:jmock-testjar:2.12.0:jmock-testjar-2.12.0.jar:efefbcf6cd294d0e29f0c46eb2a3380d4ca4e1763ff719c69e2f2ac62f564a04',
         'org.jmock:jmock:2.12.0:jmock-2.12.0.jar:266d07314c0cd343c46ff8a55601272de8cf406807caf55e6f313295f83d10be',
         'org.objenesis:objenesis:3.0.1:objenesis-3.0.1.jar:7a8ff780b9ff48415d7c705f60030b0acaa616e7f823c98eede3b63508d4e984',
-        'org.ow2.asm:asm-all:5.2:asm-all-5.2.jar:7fbffbc1db3422e2101689fd88df8384b15817b52b9b2b267b9f6d2511dc198d',
         'org.ow2.asm:asm:7.1:asm-7.1.jar:4ab2fa2b6d2cc9ccb1eaa05ea329c407b47b13ed2915f62f8c4b8cc96258d4de',
+        'org.ow2.asm:asm:9.1:asm-9.1.jar:cda4de455fab48ff0bcb7c48b4639447d4de859a7afc30a094a986f0936beba2',
         'org.whispersystems:curve25519-java:0.5.0:curve25519-java-0.5.0.jar:0aadd43cf01d11e9b58f867b3c4f25c3194e8b0623d1953d32dfbfbee009e38d',
     ]
 }

bramble-java/src/main/java/org/briarproject/bramble/network/JavaNetworkManager.java

@@ -9,16 +9,15 @@ import java.net.Inet4Address;
 import java.net.InetAddress;
 import java.net.NetworkInterface;
 import java.net.SocketException;
-import java.util.Enumeration;
 import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
-import static java.net.NetworkInterface.getNetworkInterfaces;
 import static java.util.Collections.list;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.NetworkUtils.getNetworkInterfaces;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -35,19 +34,14 @@ class JavaNetworkManager implements NetworkManager {
 	public NetworkStatus getNetworkStatus() {
 		boolean connected = false, hasIpv4 = false, hasIpv6Unicast = false;
 		try {
-			Enumeration<NetworkInterface> interfaces = getNetworkInterfaces();
+			for (NetworkInterface i : getNetworkInterfaces()) {
-			if (interfaces == null) {
+				if (i.isLoopback() || !i.isUp()) continue;
-				LOG.info("No network interfaces");
+				for (InetAddress addr : list(i.getInetAddresses())) {
-			} else {
+					connected = true;
-				for (NetworkInterface i : list(interfaces)) {
+					if (addr instanceof Inet4Address) {
-					if (i.isLoopback() || !i.isUp()) continue;
+						hasIpv4 = true;
-					for (InetAddress addr : list(i.getInetAddresses())) {
+					} else if (!addr.isMulticastAddress()) {
-						connected = true;
+						hasIpv6Unicast = true;
-						if (addr instanceof Inet4Address) {
-							hasIpv4 = true;
-						} else if (!addr.isMulticastAddress()) {
-							hasIpv6Unicast = true;
-						}
 					}
 				}
 			}

briar-android/artwork/bluetooth.svg

@@ -1,15 +1,28 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<svg
+<svg xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:cc="http://creativecommons.org/ns#" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
-   xmlns:dc="http://purl.org/dc/elements/1.1/"
+    xmlns="http://www.w3.org/2000/svg" xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
-   xmlns:cc="http://creativecommons.org/ns#"
+    xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape" width="500" height="175" viewBox="0 0 500 175"
-   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+    id="svg2" version="1.1" sodipodi:docname="bluetooth.svg" inkscape:version="1.0.2 (e86c870879, 2021-01-15)">
-   xmlns:svg="http://www.w3.org/2000/svg"
+  <sodipodi:namedview
-   xmlns="http://www.w3.org/2000/svg"
+     pagecolor="#ffffff"
-   width="499.24374"
+     bordercolor="#666666"
-   height="175.49413"
+     borderopacity="1"
-   viewBox="0 0 499.24373 175.49413"
+     objecttolerance="10"
-   id="svg2"
+     gridtolerance="10"
-   version="1.1">
+     guidetolerance="10"
+     inkscape:pageopacity="0"
+     inkscape:pageshadow="2"
+     inkscape:window-width="1920"
+     inkscape:window-height="892"
+     id="namedview10"
+     showgrid="false"
+     inkscape:zoom="0.93337848"
+     inkscape:cx="-49.861215"
+     inkscape:cy="137.66042"
+     inkscape:window-x="0"
+     inkscape:window-y="144"
+     inkscape:window-maximized="0"
+     inkscape:current-layer="svg2" />
   <defs
      id="defs4" />
   <metadata
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+     style="color:#000000;font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:medium;line-height:normal;font-family:sans-serif;text-indent:0;text-align:start;text-decoration:none;text-decoration-line:none;text-decoration-style:solid;text-decoration-color:#000000;letter-spacing:normal;word-spacing:normal;text-transform:none;writing-mode:lr-tb;direction:ltr;baseline-shift:baseline;text-anchor:start;white-space:normal;clip-rule:nonzero;display:inline;overflow:visible;visibility:visible;opacity:1;isolation:auto;mix-blend-mode:normal;color-interpolation:sRGB;color-interpolation-filters:linearRGB;solid-color:#000000;solid-opacity:1;fill:#0a3d91;fill-opacity:1;fill-rule:evenodd;stroke:none;stroke-width:7.55;stroke-linecap:round;stroke-linejoin:round;stroke-miterlimit:4;stroke-dasharray:7.55, 22.65;stroke-dashoffset:0;stroke-opacity:1;color-rendering:auto;image-rendering:auto;shape-rendering:auto;text-rendering:auto;enable-background:accumulate" />
+  <path
+     d="m 252.50083,112.08988 11.6563,-11.45156 -17.12592,-19.790888 0.0193,25.792048 -9.14185,-9.24454 -3.12531,3.09064 11.5214,11.58063 -11.49773,11.30756 c 3.03061,3.05593 0,0 3.03061,3.05593 l 9.18921,-8.97308 c 0.0443,4.73517 0.004,27.16515 0.004,27.16515 l 17.10224,-20.77257 z m -1.07721,-19.570428 6.79869,7.863838 -6.79869,6.63278 z m -0.0237,40.027828 0.0237,-15.39623 6.89338,6.9879 z"
+     id="path1536"
+     style="display:inline;opacity:1;fill:#ffffff;fill-opacity:1;stroke:none;stroke-width:0.254891"
+     sodipodi:nodetypes="ccccccccccccccccccccc" />
 </svg>

briar-android/build.gradle

@@ -26,8 +26,8 @@ android {
 	defaultConfig {
 		minSdkVersion 16
 		targetSdkVersion 30
-		versionCode 10305
+		versionCode 10308
-		versionName "1.3.5"
+		versionName "1.3.8"
 		applicationId "org.briarproject.briar.android"
 
 		vectorDrawables.useSupportLibrary = true
@@ -110,7 +110,7 @@ dependencies {
 
 	implementation 'info.guardianproject.panic:panic:1.0'
 	implementation 'info.guardianproject.trustedintents:trustedintents:0.2'
-	implementation 'de.hdodenhof:circleimageview:3.0.1'
+	implementation 'de.hdodenhof:circleimageview:3.1.0'
 	implementation 'com.google.zxing:core:3.3.3'  // newer version need minSdk 24
 	implementation 'uk.co.samuelwall:material-tap-target-prompt:3.3.0'
 	implementation 'com.vanniktech:emoji-google:0.6.0' // newer versions need minSdk 21

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/BriarUiTestComponent.java

@@ -3,6 +3,7 @@ package org.briarproject.briar.android;
 import org.briarproject.bramble.BrambleAndroidModule;
 import org.briarproject.bramble.BrambleCoreModule;
 import org.briarproject.bramble.account.BriarAccountModule;
+import org.briarproject.bramble.plugin.file.RemovableDriveModule;
 import org.briarproject.bramble.system.ClockModule;
 import org.briarproject.briar.BriarCoreModule;
 import org.briarproject.briar.android.account.SignInTestCreateAccount;
@@ -21,6 +22,7 @@ import dagger.Component;
 		AttachmentModule.class,
 		ClockModule.class,
 		MediaModule.class,
+		RemovableDriveModule.class,
 		BriarCoreModule.class,
 		BrambleAndroidModule.class,
 		BriarAccountModule.class,

briar-android/src/androidTestScreenshot/java/org/briarproject/briar/android/BriarUiTestComponent.java

@@ -3,6 +3,7 @@ package org.briarproject.briar.android;
 import org.briarproject.bramble.BrambleAndroidModule;
 import org.briarproject.bramble.BrambleCoreModule;
 import org.briarproject.bramble.account.BriarAccountModule;
+import org.briarproject.bramble.plugin.file.RemovableDriveModule;
 import org.briarproject.bramble.system.ClockModule;
 import org.briarproject.briar.BriarCoreModule;
 import org.briarproject.briar.android.attachment.AttachmentModule;
@@ -20,6 +21,7 @@ import dagger.Component;
 		AttachmentModule.class,
 		ClockModule.class,
 		MediaModule.class,
+		RemovableDriveModule.class,
 		BriarCoreModule.class,
 		BrambleAndroidModule.class,
 		BriarAccountModule.class,

briar-android/src/main/AndroidManifest.xml

@@ -344,7 +344,13 @@
 
 		<activity
 			android:name="org.briarproject.briar.android.StartupFailureActivity"
-			android:label="@string/startup_failed_activity_title" />
+			android:excludeFromRecents="true"
+			android:exported="false"
+			android:finishOnTaskLaunch="true"
+			android:label="@string/startup_failed_activity_title"
+			android:launchMode="singleInstance"
+			android:process=":briar_startup_failure"
+			android:windowSoftInputMode="adjustResize|stateHidden" />
 
 		<activity
 			android:name="org.briarproject.briar.android.settings.SettingsActivity"
@@ -456,6 +462,17 @@
 			android:label="@string/hotspot_title"
 			android:theme="@style/BriarTheme" />
 
+		<activity
+			android:name=".android.contact.connect.ConnectViaBluetoothActivity"
+			android:exported="false"
+			android:label="@string/connect_via_bluetooth_title"
+			android:parentActivityName="org.briarproject.briar.android.conversation.ConversationActivity"
+			android:theme="@style/BriarTheme">
+			<meta-data
+				android:name="android.support.PARENT_ACTIVITY"
+				android:value="org.briarproject.briar.android.conversation.ConversationActivity" />
+		</activity>
+
 	</application>
 
 	<queries>

briar-android/src/main/assets/hotspot.html

@@ -92,9 +92,9 @@
         <li id="troubleshooting_1">If you can't download the app, try it with a different web
             browser app.
         </li>
-        <li id="troubleshooting_2">Ensure that your browser is allowed to download apps directly by
+        <li id="troubleshooting_2">To install the downloaded app,
-            giving it the permission or enabling the installation of apps from "Unknown Sources" in
+            you might need to allow your browser to install unknown apps.
-            system settings.
+            We recommend to undo that after successful installation.
         </li>
     </ol>
 </div>

briar-android/src/main/java/org/briarproject/briar/android/AndroidComponent.java

@@ -35,6 +35,7 @@ import org.briarproject.briar.BriarCoreEagerSingletons;
 import org.briarproject.briar.BriarCoreModule;
 import org.briarproject.briar.android.attachment.AttachmentModule;
 import org.briarproject.briar.android.attachment.media.MediaModule;
+import org.briarproject.briar.android.contact.connect.BluetoothIntroFragment;
 import org.briarproject.briar.android.conversation.glide.BriarModelLoader;
 import org.briarproject.briar.android.hotspot.AbstractTabsFragment;
 import org.briarproject.briar.android.hotspot.FallbackFragment;
@@ -236,4 +237,6 @@ public interface AndroidComponent
 	void inject(SendFragment sendFragment);
 
 	void inject(ReceiveFragment receiveFragment);
+
+	void inject(BluetoothIntroFragment bluetoothIntroFragment);
 }

briar-android/src/main/java/org/briarproject/briar/android/AppModule.java

@@ -35,6 +35,7 @@ import org.briarproject.briar.android.account.SetupModule;
 import org.briarproject.briar.android.blog.BlogModule;
 import org.briarproject.briar.android.contact.ContactListModule;
 import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactModule;
+import org.briarproject.briar.android.contact.connect.ConnectViaBluetoothModule;
 import org.briarproject.briar.android.forum.ForumModule;
 import org.briarproject.briar.android.hotspot.HotspotModule;
 import org.briarproject.briar.android.introduction.IntroductionModule;
@@ -89,6 +90,7 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 		DevReportModule.class,
 		ContactListModule.class,
 		IntroductionModule.class,
+		ConnectViaBluetoothModule.class,
 		// below need to be within same scope as ViewModelProvider.Factory
 		BlogModule.class,
 		ForumModule.class,
@@ -157,7 +159,8 @@ public class AppModule {
 	@Singleton
 	PluginConfig providePluginConfig(AndroidBluetoothPluginFactory bluetooth,
 			AndroidTorPluginFactory tor, AndroidLanTcpPluginFactory lan,
-			AndroidRemovableDrivePluginFactory drive) {
+			AndroidRemovableDrivePluginFactory drive,
+			FeatureFlags featureFlags) {
 		@NotNullByDefault
 		PluginConfig pluginConfig = new PluginConfig() {
 
@@ -168,7 +171,11 @@ public class AppModule {
 
 			@Override
 			public Collection<SimplexPluginFactory> getSimplexFactories() {
-				return SDK_INT >= 19 ? singletonList(drive) : emptyList();
+				if (SDK_INT >= 19 && featureFlags.shouldEnableTransferData()) {
+					return singletonList(drive);
+				} else {
+					return emptyList();
+				}
 			}
 
 			@Override
@@ -306,11 +313,6 @@ public class AppModule {
 				return true;
 			}
 
-			@Override
-			public boolean shouldEnableConnectViaBluetooth() {
-				return IS_DEBUG_BUILD;
-			}
-
 			@Override
 			public boolean shouldEnableTransferData() {
 				return IS_DEBUG_BUILD;

briar-android/src/main/java/org/briarproject/briar/android/BriarService.java

@@ -3,7 +3,6 @@ package org.briarproject.briar.android;
 import android.app.Notification;
 import android.app.NotificationChannel;
 import android.app.NotificationManager;
-import android.app.PendingIntent;
 import android.app.Service;
 import android.content.BroadcastReceiver;
 import android.content.ComponentName;
@@ -34,11 +33,7 @@ import java.util.logging.Logger;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
-import androidx.core.app.NotificationCompat;
-
-import static android.app.NotificationManager.IMPORTANCE_DEFAULT;
 import static android.app.NotificationManager.IMPORTANCE_LOW;
-import static android.app.PendingIntent.FLAG_UPDATE_CURRENT;
 import static android.content.Intent.ACTION_SHUTDOWN;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TASK;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
@@ -55,7 +50,6 @@ import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResul
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.briar.android.BriarApplication.ENTRY_ACTIVITY;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.FAILURE_CHANNEL_ID;
-import static org.briarproject.briar.api.android.AndroidNotificationManager.FAILURE_NOTIFICATION_ID;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.ONGOING_CHANNEL_ID;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.ONGOING_CHANNEL_OLD_ID;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.ONGOING_NOTIFICATION_ID;
@@ -66,8 +60,6 @@ public class BriarService extends Service {
 
 	public static String EXTRA_START_RESULT =
 			"org.briarproject.briar.START_RESULT";
-	public static String EXTRA_NOTIFICATION_ID =
-			"org.briarproject.briar.FAILURE_NOTIFICATION_ID";
 	public static String EXTRA_STARTUP_FAILED =
 			"org.briarproject.briar.STARTUP_FAILED";
 
@@ -135,12 +127,11 @@ public class BriarService extends Service {
 				ongoingChannel.setLockscreenVisibility(VISIBILITY_SECRET);
 				ongoingChannel.setShowBadge(false);
 				nm.createNotificationChannel(ongoingChannel);
-				NotificationChannel failureChannel = new NotificationChannel(
+				// Delete the unused channel previously used for startup
-						FAILURE_CHANNEL_ID,
+				// failure notifications
-						getString(R.string.startup_failed_notification_title),
+				// TODO: Remove this ID after a reasonable upgrade period
-						IMPORTANCE_DEFAULT);
+				//  (added 2021-07-12)
-				failureChannel.setLockscreenVisibility(VISIBILITY_SECRET);
+				nm.deleteNotificationChannel(FAILURE_CHANNEL_ID);
-				nm.createNotificationChannel(failureChannel);
 			}
 			Notification foregroundNotification =
 					notificationManager.getForegroundNotification();
@@ -156,7 +147,7 @@ public class BriarService extends Service {
 				} else {
 					if (LOG.isLoggable(WARNING))
 						LOG.warning("Startup failed: " + result);
-					showStartupFailureNotification(result);
+					showStartupFailure(result);
 					stopSelf();
 				}
 			}, "LifecycleStartup");
@@ -182,29 +173,13 @@ public class BriarService extends Service {
 		Localizer.getInstance().setLocale(this);
 	}
 
-	private void showStartupFailureNotification(StartResult result) {
+	private void showStartupFailure(StartResult result) {
 		androidExecutor.runOnUiThread(() -> {
-			NotificationCompat.Builder b = new NotificationCompat.Builder(
+			// Bring the entry activity to the front to clear the back stack
-					BriarService.this, FAILURE_CHANNEL_ID);
+			Intent i = new Intent(BriarService.this, ENTRY_ACTIVITY);
-			b.setSmallIcon(android.R.drawable.stat_notify_error);
-			b.setContentTitle(getText(
-					R.string.startup_failed_notification_title));
-			b.setContentText(getText(
-					R.string.startup_failed_notification_text));
-			Intent i = new Intent(BriarService.this,
-					StartupFailureActivity.class);
-			i.setFlags(FLAG_ACTIVITY_NEW_TASK);
-			i.putExtra(EXTRA_START_RESULT, result);
-			i.putExtra(EXTRA_NOTIFICATION_ID, FAILURE_NOTIFICATION_ID);
-			b.setContentIntent(PendingIntent.getActivity(BriarService.this,
-					0, i, FLAG_UPDATE_CURRENT));
-			NotificationManager nm = (NotificationManager)
-					requireNonNull(getSystemService(NOTIFICATION_SERVICE));
-			nm.notify(FAILURE_NOTIFICATION_ID, b.build());
-			// Bring the dashboard to the front to clear the back stack
-			i = new Intent(BriarService.this, ENTRY_ACTIVITY);
 			i.setFlags(FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TOP);
 			i.putExtra(EXTRA_STARTUP_FAILED, true);
+			i.putExtra(EXTRA_START_RESULT, result);
 			startActivity(i);
 		});
 	}

briar-android/src/main/java/org/briarproject/briar/android/StartupFailureActivity.java

@@ -1,6 +1,5 @@
 package org.briarproject.briar.android;
 
-import android.app.NotificationManager;
 import android.content.Intent;
 import android.os.Bundle;
 
@@ -15,9 +14,7 @@ import org.briarproject.briar.android.fragment.ErrorFragment;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
-import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult;
-import static org.briarproject.briar.android.BriarService.EXTRA_NOTIFICATION_ID;
 import static org.briarproject.briar.android.BriarService.EXTRA_START_RESULT;
 
 @MethodsNotNullByDefault
@@ -41,14 +38,6 @@ public class StartupFailureActivity extends BaseActivity implements
 	private void handleIntent(Intent i) {
 		StartResult result =
 				(StartResult) i.getSerializableExtra(EXTRA_START_RESULT);
-		int notificationId = i.getIntExtra(EXTRA_NOTIFICATION_ID, -1);
-
-		// cancel notification
-		if (notificationId > -1) {
-			Object o = getSystemService(NOTIFICATION_SERVICE);
-			NotificationManager nm = (NotificationManager) requireNonNull(o);
-			nm.cancel(notificationId);
-		}
 
 		// show proper error message
 		int errorRes;
@@ -78,5 +67,4 @@ public class StartupFailureActivity extends BaseActivity implements
 	public void runOnDbThread(@NonNull Runnable runnable) {
 		throw new UnsupportedOperationException();
 	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityComponent.java

@@ -28,8 +28,8 @@ import org.briarproject.briar.android.contact.add.remote.AddContactActivity;
 import org.briarproject.briar.android.contact.add.remote.LinkExchangeFragment;
 import org.briarproject.briar.android.contact.add.remote.NicknameFragment;
 import org.briarproject.briar.android.contact.add.remote.PendingContactListActivity;
+import org.briarproject.briar.android.contact.connect.ConnectViaBluetoothActivity;
 import org.briarproject.briar.android.conversation.AliasDialogFragment;
-import org.briarproject.briar.android.conversation.BluetoothConnecterDialogFragment;
 import org.briarproject.briar.android.conversation.ConversationActivity;
 import org.briarproject.briar.android.conversation.ConversationSettingsDialog;
 import org.briarproject.briar.android.conversation.ImageActivity;
@@ -238,9 +238,6 @@ public interface ActivityComponent {
 
 	void inject(ConversationSettingsDialog dialog);
 
-	void inject(
-			BluetoothConnecterDialogFragment bluetoothConnecterDialogFragment);
-
 	void inject(RssFeedImportFragment fragment);
 
 	void inject(RssFeedManageFragment fragment);
@@ -248,4 +245,6 @@ public interface ActivityComponent {
 	void inject(RssFeedImportFailedDialogFragment fragment);
 
 	void inject(RssFeedDeleteFeedDialogFragment fragment);
+
+	void inject(ConnectViaBluetoothActivity connectViaBluetoothActivity);
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostItem.java

@@ -1,10 +1,10 @@
 package org.briarproject.briar.android.blog;
 
 import org.briarproject.bramble.api.identity.Author;
-import org.briarproject.briar.api.identity.AuthorInfo;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.api.blog.BlogPostHeader;
+import org.briarproject.briar.api.identity.AuthorInfo;
 
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.NotThreadSafe;
@@ -50,7 +50,7 @@ public class BlogPostItem implements Comparable<BlogPostItem> {
 		return text;
 	}
 
-	public boolean isRssFeed() {
+	boolean isRssFeed() {
 		return header.isRssFeed();
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostViewHolder.java

@@ -20,6 +20,7 @@ import androidx.annotation.UiThread;
 import androidx.core.view.ViewCompat;
 import androidx.recyclerview.widget.RecyclerView;
 
+import static android.os.Build.VERSION.SDK_INT;
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
@@ -44,6 +45,7 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 	private final TextView text;
 	private final ViewGroup commentContainer;
 	private final boolean fullText, authorClickable;
+	private final int padding;
 
 	private final OnBlogPostClickListener listener;
 
@@ -61,6 +63,8 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 		reblogButton = v.findViewById(R.id.commentView);
 		text = v.findViewById(R.id.textView);
 		commentContainer = v.findViewById(R.id.commentContainer);
+		padding = ctx.getResources()
+				.getDimensionPixelSize(R.dimen.listitem_vertical_margin);
 	}
 
 	void hideReblogButton() {
@@ -129,6 +133,12 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 		} else {
 			reblogger.setVisibility(GONE);
 		}
+
+		// Apply Android 4 padding fix after setting up author/reblogger views
+		if (SDK_INT < 21) {
+			reblogger.setPadding(padding, padding, padding, padding);
+			author.setPadding(padding, padding, padding, padding);
+		}
 	}
 
 	private void onBindComment(BlogCommentItem item, boolean authorClickable) {

briar-android/src/main/java/org/briarproject/briar/android/blog/RssFeedActivity.java

@@ -57,8 +57,12 @@ public class RssFeedActivity extends BriarActivity
 				onBackPressed();
 			}
 		} else if (result == FAILED) {
+			String url = viewModel.getUrlFailedImport();
+			if (url == null) {
+				throw new AssertionError();
+			}
 			RssFeedImportFailedDialogFragment dialog =
-					RssFeedImportFailedDialogFragment.newInstance();
+					RssFeedImportFailedDialogFragment.newInstance(url);
 			dialog.show(getSupportFragmentManager(),
 					RssFeedImportFailedDialogFragment.TAG);
 		} else if (result == EXISTS) {

briar-android/src/main/java/org/briarproject/briar/android/blog/RssFeedImportFailedDialogFragment.java

@@ -25,8 +25,15 @@ public class RssFeedImportFailedDialogFragment extends DialogFragment {
 	ViewModelProvider.Factory viewModelFactory;
 	private RssFeedViewModel viewModel;
 
-	static RssFeedImportFailedDialogFragment newInstance() {
+	private static final String ARG_URL = "url";
-		return new RssFeedImportFailedDialogFragment();
+
+	static RssFeedImportFailedDialogFragment newInstance(String retryUrl) {
+		Bundle args = new Bundle();
+		args.putString(ARG_URL, retryUrl);
+		RssFeedImportFailedDialogFragment f =
+				new RssFeedImportFailedDialogFragment();
+		f.setArguments(args);
+		return f;
 	}
 
 	@Override
@@ -45,8 +52,8 @@ public class RssFeedImportFailedDialogFragment extends DialogFragment {
 						R.style.BriarDialogTheme);
 		builder.setMessage(R.string.blogs_rss_feeds_import_error);
 		builder.setNegativeButton(R.string.cancel, null);
-		builder.setPositiveButton(R.string.try_again_button,
+		builder.setPositiveButton(R.string.try_again_button, (dialog, which) ->
-				(dialog, which) -> viewModel.retryImportFeed());
+				viewModel.importFeed(requireArguments().getString(ARG_URL)));
 
 		return builder.create();
 	}

briar-android/src/main/java/org/briarproject/briar/android/blog/RssFeedManageFragment.java

@@ -20,7 +20,6 @@ import org.briarproject.briar.api.feed.Feed;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
-import androidx.annotation.NonNull;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.recyclerview.widget.LinearLayoutManager;
 

briar-android/src/main/java/org/briarproject/briar/android/blog/RssFeedViewModel.java

@@ -159,11 +159,9 @@ class RssFeedViewModel extends DbViewModel {
 		});
 	}
 
-	void retryImportFeed() {
+	@Nullable
-		if (urlFailedImport == null) {
+	String getUrlFailedImport() {
-			throw new AssertionError();
+		return urlFailedImport;
-		}
-		importFeed(urlFailedImport);
 	}
 
 	private boolean exists(String url) {

briar-android/src/main/java/org/briarproject/briar/android/contact/add/remote/LinkExchangeFragment.java

@@ -59,7 +59,7 @@ public class LinkExchangeFragment extends BaseFragment
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
-		viewModel = new ViewModelProvider(getActivity(), viewModelFactory)
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
 				.get(AddContactViewModel.class);
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/contact/connect/BluetoothConditionManager.java

@@ -0,0 +1,87 @@
+package org.briarproject.briar.android.contact.connect;
+
+import android.app.Activity;
+import android.content.Context;
+
+import org.briarproject.briar.R;
+
+import androidx.activity.result.ActivityResultLauncher;
+import androidx.annotation.Nullable;
+import androidx.annotation.UiThread;
+import androidx.appcompat.app.AlertDialog;
+
+import static android.Manifest.permission.ACCESS_FINE_LOCATION;
+import static android.os.Build.VERSION.SDK_INT;
+import static androidx.core.app.ActivityCompat.shouldShowRequestPermissionRationale;
+import static org.briarproject.briar.android.util.UiUtils.getGoToSettingsListener;
+import static org.briarproject.briar.android.util.UiUtils.isLocationEnabled;
+import static org.briarproject.briar.android.util.UiUtils.showLocationDialog;
+
+class BluetoothConditionManager {
+
+	private enum Permission {
+		UNKNOWN, GRANTED, SHOW_RATIONALE, PERMANENTLY_DENIED
+	}
+
+	private Permission locationPermission = Permission.UNKNOWN;
+
+	/**
+	 * Call this when the using activity or fragment starts,
+	 * because permissions might have changed while it was stopped.
+	 */
+	void reset() {
+		locationPermission = Permission.UNKNOWN;
+	}
+
+	@UiThread
+	void onLocationPermissionResult(Activity activity,
+			@Nullable Boolean result) {
+		if (result != null && result) {
+			locationPermission = Permission.GRANTED;
+		} else if (shouldShowRequestPermissionRationale(activity,
+				ACCESS_FINE_LOCATION)) {
+			locationPermission = Permission.SHOW_RATIONALE;
+		} else {
+			locationPermission = Permission.PERMANENTLY_DENIED;
+		}
+	}
+
+	boolean areRequirementsFulfilled(Context ctx,
+			ActivityResultLauncher<String> permissionRequest,
+			Runnable onLocationDenied) {
+		boolean permissionGranted =
+				SDK_INT < 23 || locationPermission == Permission.GRANTED;
+		boolean locationEnabled = isLocationEnabled(ctx);
+		if (permissionGranted && locationEnabled) return true;
+
+		if (locationPermission == Permission.PERMANENTLY_DENIED) {
+			showDenialDialog(ctx, onLocationDenied);
+		} else if (locationPermission == Permission.SHOW_RATIONALE) {
+			showRationale(ctx, permissionRequest);
+		} else if (!locationEnabled) {
+			showLocationDialog(ctx);
+		}
+		return false;
+	}
+
+	private void showDenialDialog(Context ctx, Runnable onLocationDenied) {
+		new AlertDialog.Builder(ctx, R.style.BriarDialogTheme)
+				.setTitle(R.string.permission_location_title)
+				.setMessage(R.string.permission_location_denied_body)
+				.setPositiveButton(R.string.ok, getGoToSettingsListener(ctx))
+				.setNegativeButton(R.string.cancel, (v, d) ->
+						onLocationDenied.run())
+				.show();
+	}
+
+	private void showRationale(Context ctx,
+			ActivityResultLauncher<String> permissionRequest) {
+		new AlertDialog.Builder(ctx, R.style.BriarDialogTheme)
+				.setTitle(R.string.permission_location_title)
+				.setMessage(R.string.permission_location_request_body)
+				.setPositiveButton(R.string.ok, (dialog, which) ->
+						permissionRequest.launch(ACCESS_FINE_LOCATION))
+				.show();
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/connect/BluetoothIntroFragment.java

@@ -0,0 +1,109 @@
+package org.briarproject.briar.android.contact.connect;
+
+import android.app.Activity;
+import android.content.Context;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.Button;
+import android.widget.Toast;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.util.ActivityLaunchers.RequestBluetoothDiscoverable;
+
+import javax.inject.Inject;
+
+import androidx.activity.result.ActivityResultLauncher;
+import androidx.activity.result.contract.ActivityResultContracts.RequestPermission;
+import androidx.annotation.Nullable;
+import androidx.fragment.app.Fragment;
+import androidx.lifecycle.ViewModelProvider;
+
+import static android.Manifest.permission.ACCESS_FINE_LOCATION;
+import static android.widget.Toast.LENGTH_LONG;
+import static org.briarproject.briar.android.AppModule.getAndroidComponent;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class BluetoothIntroFragment extends Fragment {
+
+	final static String TAG = BluetoothIntroFragment.class.getName();
+
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private final BluetoothConditionManager conditionManager =
+			new BluetoothConditionManager();
+	private ConnectViaBluetoothViewModel viewModel;
+
+	private final ActivityResultLauncher<Integer> bluetoothDiscoverableRequest =
+			registerForActivityResult(new RequestBluetoothDiscoverable(),
+					this::onBluetoothDiscoverable);
+	private final ActivityResultLauncher<String> permissionRequest =
+			registerForActivityResult(new RequestPermission(),
+					this::onPermissionRequestResult);
+
+	@Override
+	public void onAttach(Context context) {
+		super.onAttach(context);
+		getAndroidComponent(requireContext()).inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(ConnectViaBluetoothViewModel.class);
+	}
+
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+		return inflater
+				.inflate(R.layout.fragment_bluetooth_intro, container, false);
+	}
+
+	@Override
+	public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
+		Button startButton = view.findViewById(R.id.startButton);
+		startButton.setOnClickListener(this::onStartClicked);
+	}
+
+	@Override
+	public void onStart() {
+		super.onStart();
+		conditionManager.reset();
+	}
+
+	private void onStartClicked(View v) {
+		if (viewModel.shouldStartFlow()) {
+			// The dialog starts a permission request which comes back as true
+			// if the permission is already granted.
+			// So we can use the request as a generic entry point
+			// to the whole flow.
+			permissionRequest.launch(ACCESS_FINE_LOCATION);
+		}
+	}
+
+	private void onPermissionRequestResult(@Nullable Boolean result) {
+		Activity a = requireActivity();
+		// update permission result in BluetoothConnecter
+		conditionManager.onLocationPermissionResult(a, result);
+		// what to do when the user denies granting the location permission
+		Runnable onLocationPermissionDenied = () -> Toast.makeText(
+				requireContext(),
+				R.string.connect_via_bluetooth_no_location_permission,
+				LENGTH_LONG).show();
+		// if requirements are fulfilled, request Bluetooth discoverability
+		if (conditionManager.areRequirementsFulfilled(a, permissionRequest,
+				onLocationPermissionDenied)) {
+			bluetoothDiscoverableRequest.launch(120); // for 2min
+		}
+	}
+
+	private void onBluetoothDiscoverable(@Nullable Boolean result) {
+		if (result != null && result) {
+			viewModel.onBluetoothDiscoverable();
+		}
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/connect/BluetoothProgressFragment.java

@@ -0,0 +1,29 @@
+package org.briarproject.briar.android.contact.connect;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.briar.R;
+
+import androidx.annotation.Nullable;
+import androidx.fragment.app.Fragment;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class BluetoothProgressFragment extends Fragment {
+
+	final static String TAG = BluetoothProgressFragment.class.getName();
+
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+		return inflater
+				.inflate(R.layout.fragment_bluetooth_progress, container, false);
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/connect/ConnectViaBluetoothActivity.java

@@ -0,0 +1,98 @@
+package org.briarproject.briar.android.contact.connect;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.view.MenuItem;
+import android.widget.Toast;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.activity.BriarActivity;
+
+import javax.inject.Inject;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.fragment.app.Fragment;
+import androidx.lifecycle.ViewModelProvider;
+
+import static android.widget.Toast.LENGTH_LONG;
+import static java.util.Objects.requireNonNull;
+import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
+import static org.briarproject.briar.android.util.UiUtils.showFragment;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class ConnectViaBluetoothActivity extends BriarActivity {
+
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private ConnectViaBluetoothViewModel viewModel;
+
+	@Override
+	public void injectActivity(ActivityComponent component) {
+		component.inject(this);
+
+		viewModel = new ViewModelProvider(this, viewModelFactory)
+				.get(ConnectViaBluetoothViewModel.class);
+	}
+
+	@Override
+	public void onCreate(@Nullable Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+
+		Intent intent = requireNonNull(getIntent());
+		int contactId = intent.getIntExtra(CONTACT_ID, -1);
+		if (contactId == -1) throw new IllegalArgumentException("ContactId");
+		viewModel.setContactId(new ContactId(contactId));
+
+		setContentView(R.layout.activity_fragment_container);
+
+		viewModel.getState().observeEvent(this, this::onStateChanged);
+
+		if (savedInstanceState == null) {
+			Fragment f = new BluetoothIntroFragment();
+			String tag = BluetoothIntroFragment.TAG;
+			getSupportFragmentManager().beginTransaction()
+					.replace(R.id.fragmentContainer, f, tag)
+					.commitNow();
+		}
+	}
+
+	@Override
+	public void onStart() {
+		super.onStart();
+		viewModel.reset();
+	}
+
+	@Override
+	public boolean onOptionsItemSelected(@NonNull MenuItem item) {
+		if (item.getItemId() == android.R.id.home) {
+			onBackPressed();
+			return true;
+		}
+		return super.onOptionsItemSelected(item);
+	}
+
+	private void onStateChanged(ConnectViaBluetoothState state) {
+		if (state instanceof ConnectViaBluetoothState.Connecting) {
+			Fragment f = new BluetoothProgressFragment();
+			String tag = BluetoothProgressFragment.TAG;
+			showFragment(getSupportFragmentManager(), f, tag, false);
+		} else if (state instanceof ConnectViaBluetoothState.Success) {
+			Toast.makeText(this, R.string.connect_via_bluetooth_success,
+					LENGTH_LONG).show();
+			supportFinishAfterTransition();
+		} else if (state instanceof ConnectViaBluetoothState.Error) {
+			Toast.makeText(this,
+					((ConnectViaBluetoothState.Error) state).errorRes,
+					LENGTH_LONG).show();
+			supportFinishAfterTransition();
+		} else throw new AssertionError();
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/connect/ConnectViaBluetoothModule.java

@@ -0,0 +1,19 @@
+package org.briarproject.briar.android.contact.connect;
+
+import org.briarproject.briar.android.viewmodel.ViewModelKey;
+
+import androidx.lifecycle.ViewModel;
+import dagger.Binds;
+import dagger.Module;
+import dagger.multibindings.IntoMap;
+
+@Module
+public abstract class ConnectViaBluetoothModule {
+
+	@Binds
+	@IntoMap
+	@ViewModelKey(ConnectViaBluetoothViewModel.class)
+	abstract ViewModel bindContactListViewModel(
+			ConnectViaBluetoothViewModel connectViaBluetoothViewModel);
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/connect/ConnectViaBluetoothState.java

@@ -0,0 +1,23 @@
+package org.briarproject.briar.android.contact.connect;
+
+import androidx.annotation.StringRes;
+
+abstract class ConnectViaBluetoothState {
+
+	static class Connecting extends ConnectViaBluetoothState {
+	}
+
+	static class Success extends ConnectViaBluetoothState {
+	}
+
+	static class Error extends ConnectViaBluetoothState {
+		@StringRes
+		final int errorRes;
+
+		Error(@StringRes int errorRes) {
+			this.errorRes = errorRes;
+		}
+	}
+
+}
+

briar-android/src/main/java/org/briarproject/briar/android/contact/connect/ConnectViaBluetoothViewModel.java

@@ -1,19 +1,20 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.contact.connect;
 
-import android.app.Activity;
 import android.app.Application;
 import android.bluetooth.BluetoothAdapter;
-import android.content.Context;
-import android.widget.Toast;
 
 import org.briarproject.bramble.api.connection.ConnectionManager;
 import org.briarproject.bramble.api.connection.ConnectionRegistry;
 import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.PluginManager;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.plugin.event.ConnectionOpenedEvent;
@@ -21,23 +22,22 @@ import org.briarproject.bramble.api.properties.TransportPropertyManager;
 import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.plugin.bluetooth.BluetoothPlugin;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.contact.ContactItem;
+import org.briarproject.briar.android.contact.connect.ConnectViaBluetoothState.Connecting;
+import org.briarproject.briar.android.contact.connect.ConnectViaBluetoothState.Success;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
+import org.briarproject.briar.android.viewmodel.LiveEvent;
+import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
 
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
+import javax.annotation.Nullable;
 import javax.inject.Inject;
 
-import androidx.activity.result.ActivityResultLauncher;
 import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
-import androidx.annotation.StringRes;
 import androidx.annotation.UiThread;
-import androidx.appcompat.app.AlertDialog;
 
-import static android.Manifest.permission.ACCESS_FINE_LOCATION;
+import static java.util.Objects.requireNonNull;
-import static android.os.Build.VERSION.SDK_INT;
-import static androidx.core.app.ActivityCompat.shouldShowRequestPermissionRationale;
 import static java.util.concurrent.TimeUnit.SECONDS;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
@@ -46,48 +46,50 @@ import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_UUID;
 import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
-import static org.briarproject.briar.android.util.UiUtils.getGoToSettingsListener;
-import static org.briarproject.briar.android.util.UiUtils.isLocationEnabled;
-import static org.briarproject.briar.android.util.UiUtils.showLocationDialog;
 
-class BluetoothConnecter implements EventListener {
+@UiThread
+@NotNullByDefault
+class ConnectViaBluetoothViewModel extends DbViewModel implements
+		EventListener {
 
-	private final Logger LOG = getLogger(BluetoothConnecter.class.getName());
+	private final Logger LOG =
+			getLogger(ConnectViaBluetoothViewModel.class.getName());
 
 	private final long BT_ACTIVE_TIMEOUT = SECONDS.toMillis(5);
 
-	private enum Permission {
-		UNKNOWN, GRANTED, SHOW_RATIONALE, PERMANENTLY_DENIED
-	}
-
-	private final Application app;
 	private final PluginManager pluginManager;
 	private final Executor ioExecutor;
-	private final AndroidExecutor androidExecutor;
 	private final ConnectionRegistry connectionRegistry;
+	@Nullable
 	private final BluetoothAdapter bt = BluetoothAdapter.getDefaultAdapter();
 	private final EventBus eventBus;
 	private final TransportPropertyManager transportPropertyManager;
 	private final ConnectionManager connectionManager;
 
+	@Nullable
 	private volatile BluetoothPlugin bluetoothPlugin;
-
+	@Nullable
-	private Permission locationPermission = Permission.UNKNOWN;
 	private ContactId contactId = null;
 
+	private final MutableLiveEvent<ConnectViaBluetoothState> state =
+			new MutableLiveEvent<>();
+
 	@Inject
-	BluetoothConnecter(Application app,
+	ConnectViaBluetoothViewModel(
+			Application app,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
 			PluginManager pluginManager,
 			@IoExecutor Executor ioExecutor,
-			AndroidExecutor androidExecutor,
 			ConnectionRegistry connectionRegistry,
 			EventBus eventBus,
 			TransportPropertyManager transportPropertyManager,
 			ConnectionManager connectionManager) {
-		this.app = app;
+		super(app, dbExecutor, lifecycleManager, db, androidExecutor);
 		this.pluginManager = pluginManager;
 		this.ioExecutor = ioExecutor;
-		this.androidExecutor = androidExecutor;
 		this.bluetoothPlugin = (BluetoothPlugin) pluginManager.getPlugin(ID);
 		this.connectionRegistry = connectionRegistry;
 		this.eventBus = eventBus;
@@ -95,20 +97,22 @@ class BluetoothConnecter implements EventListener {
 		this.connectionManager = connectionManager;
 	}
 
-	boolean isConnectedViaBluetooth(ContactId contactId) {
+	@Override
-		return connectionRegistry.isConnected(contactId, ID);
+	protected void onCleared() {
-	}
+		stopConnecting();
-
-	boolean isDiscovering() {
-		return bluetoothPlugin.isDiscovering();
 	}
 
 	/**
-	 * Call this when the using activity or fragment starts,
+	 * Set this as soon as it becomes available.
-	 * because permissions might have changed while it was stopped.
+	 */
+	void setContactId(ContactId contactId) {
+		this.contactId = contactId;
+	}
+
+	/**
+	 * Call this when the using activity or fragment starts.
 	 */
 	void reset() {
-		locationPermission = Permission.UNKNOWN;
 		// When this class is instantiated before we are logged in
 		// (like when returning to a killed activity), bluetoothPlugin would be
 		// null and we consider bluetooth not supported. So reset here.
@@ -116,94 +120,52 @@ class BluetoothConnecter implements EventListener {
 	}
 
 	@UiThread
-	void onLocationPermissionResult(Activity activity,
+	boolean shouldStartFlow() {
-			@Nullable Boolean result) {
+		if (isBluetoothNotSupported()) {
-		if (result != null && result) {
+			state.setEvent(new ConnectViaBluetoothState.Error(
-			locationPermission = Permission.GRANTED;
+					R.string.bt_plugin_status_inactive));
-		} else if (shouldShowRequestPermissionRationale(activity,
+			return false;
-				ACCESS_FINE_LOCATION)) {
+		} else if (isConnectedViaBluetooth()) {
-			locationPermission = Permission.SHOW_RATIONALE;
+			state.setEvent(new Success());
-		} else {
+			return false;
-			locationPermission = Permission.PERMANENTLY_DENIED;
+		} else if (isDiscovering()) {
+			state.setEvent(new ConnectViaBluetoothState.Error(
+					R.string.connect_via_bluetooth_already_discovering));
+			return false;
 		}
+		return true;
 	}
 
-	boolean isBluetoothNotSupported() {
+	private boolean isBluetoothNotSupported() {
 		return bt == null || bluetoothPlugin == null;
 	}
 
-	boolean areRequirementsFulfilled(Context ctx,
+	private boolean isDiscovering() {
-			ActivityResultLauncher<String> permissionRequest,
+		// we should not be calling this if isBluetoothNotSupported() is true
-			Runnable onLocationDenied) {
+		return requireNonNull(bluetoothPlugin).isDiscovering();
-		boolean permissionGranted =
-				SDK_INT < 23 || locationPermission == Permission.GRANTED;
-		boolean locationEnabled = isLocationEnabled(ctx);
-		if (permissionGranted && locationEnabled) return true;
-
-		if (locationPermission == Permission.PERMANENTLY_DENIED) {
-			showDenialDialog(ctx, onLocationDenied);
-		} else if (locationPermission == Permission.SHOW_RATIONALE) {
-			showRationale(ctx, permissionRequest);
-		} else if (!locationEnabled) {
-			showLocationDialog(ctx);
-		}
-		return false;
 	}
 
-	private void showDenialDialog(Context ctx, Runnable onLocationDenied) {
+	private boolean isConnectedViaBluetooth() {
-		new AlertDialog.Builder(ctx, R.style.BriarDialogTheme)
+		return connectionRegistry.isConnected(requireNonNull(contactId), ID);
-				.setTitle(R.string.permission_location_title)
-				.setMessage(R.string.permission_location_denied_body)
-				.setPositiveButton(R.string.ok, getGoToSettingsListener(ctx))
-				.setNegativeButton(R.string.cancel, (v, d) ->
-						onLocationDenied.run())
-				.show();
-	}
-
-	private void showRationale(Context ctx,
-			ActivityResultLauncher<String> permissionRequest) {
-		new AlertDialog.Builder(ctx, R.style.BriarDialogTheme)
-				.setTitle(R.string.permission_location_title)
-				.setMessage(R.string.permission_location_request_body)
-				.setPositiveButton(R.string.ok, (dialog, which) ->
-						permissionRequest.launch(ACCESS_FINE_LOCATION))
-				.show();
 	}
 
 	@UiThread
-	void onBluetoothDiscoverable(ContactItem contact) {
+	void onBluetoothDiscoverable() {
-		contactId = contact.getContact().getId();
+		ContactId contactId = requireNonNull(this.contactId);
-		connect();
+		BluetoothPlugin bluetoothPlugin = requireNonNull(this.bluetoothPlugin);
-	}
 
-	@UiThread
+		state.setEvent(new Connecting());
-	@Override
-	public void eventOccurred(@NonNull Event e) {
-		if (e instanceof ConnectionOpenedEvent) {
-			ConnectionOpenedEvent c = (ConnectionOpenedEvent) e;
-			if (c.getContactId().equals(contactId) && c.isIncoming() &&
-					c.getTransportId() == ID) {
-				if (bluetoothPlugin != null) {
-					bluetoothPlugin.stopDiscoverAndConnect();
-				}
-				LOG.info("Contact connected to us");
-				showToast(R.string.toast_connect_via_bluetooth_success);
-			}
-		}
-	}
 
-	private void connect() {
 		bluetoothPlugin.disablePolling();
 		pluginManager.setPluginEnabled(ID, true);
-
 		ioExecutor.execute(() -> {
 			try {
 				if (!waitForBluetoothActive()) {
-					showToast(R.string.bt_plugin_status_inactive);
+					state.postEvent(new ConnectViaBluetoothState.Error(
+							R.string.bt_plugin_status_inactive));
 					LOG.warning("Bluetooth plugin didn't become active");
 					return;
 				}
-				showToast(R.string.toast_connect_via_bluetooth_start);
 				eventBus.addListener(this);
 				try {
 					String uuid = null;
@@ -226,7 +188,7 @@ class BluetoothConnecter implements EventListener {
 						LOG.info("Could connect, handling connection");
 						connectionManager
 								.manageOutgoingConnection(contactId, ID, conn);
-						showToast(R.string.toast_connect_via_bluetooth_success);
+						state.postEvent(new Success());
 					}
 				} finally {
 					eventBus.removeListener(this);
@@ -237,8 +199,23 @@ class BluetoothConnecter implements EventListener {
 		});
 	}
 
+	@UiThread
+	@Override
+	public void eventOccurred(@NonNull Event e) {
+		if (e instanceof ConnectionOpenedEvent) {
+			ConnectionOpenedEvent c = (ConnectionOpenedEvent) e;
+			if (c.getContactId().equals(contactId) && c.isIncoming() &&
+					c.getTransportId() == ID) {
+				stopConnecting();
+				LOG.info("Contact connected to us");
+				state.postEvent(new Success());
+			}
+		}
+	}
+
 	@IoExecutor
 	private boolean waitForBluetoothActive() {
+		BluetoothPlugin bluetoothPlugin = requireNonNull(this.bluetoothPlugin);
 		long left = BT_ACTIVE_TIMEOUT;
 		final long sleep = 250;
 		try {
@@ -264,9 +241,9 @@ class BluetoothConnecter implements EventListener {
 		final long sleep = 250;
 		try {
 			while (left > 0) {
-				if (isConnectedViaBluetooth(contactId)) {
+				if (isConnectedViaBluetooth()) {
 					LOG.info("Failed to connect, but contact connected");
-					// no Toast needed here, as it gets shown when
+					// no success state needed here, as it gets shown when
 					// ConnectionOpenedEvent is received
 					return;
 				}
@@ -277,13 +254,19 @@ class BluetoothConnecter implements EventListener {
 			Thread.currentThread().interrupt();
 		}
 		LOG.warning("Failed to connect");
-		showToast(R.string.toast_connect_via_bluetooth_error);
+		state.postEvent(new ConnectViaBluetoothState.Error(
+				R.string.connect_via_bluetooth_error));
 	}
 
-	private void showToast(@StringRes int res) {
+	private void stopConnecting() {
-		androidExecutor.runOnUiThread(() ->
+		BluetoothPlugin bluetoothPlugin = this.bluetoothPlugin;
-				Toast.makeText(app, res, Toast.LENGTH_LONG).show()
+		if (bluetoothPlugin != null) {
-		);
+			bluetoothPlugin.stopDiscoverAndConnect();
+		}
+	}
+
+	LiveEvent<ConnectViaBluetoothState> getState() {
+		return state;
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/conversation/BluetoothConnecterDialogFragment.java

@@ -1,151 +0,0 @@
-package org.briarproject.briar.android.conversation;
-
-import android.app.Activity;
-import android.app.Dialog;
-import android.content.Context;
-import android.os.Bundle;
-import android.view.View;
-import android.widget.Button;
-import android.widget.Toast;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.briar.R;
-import org.briarproject.briar.android.activity.BaseActivity;
-import org.briarproject.briar.android.contact.ContactItem;
-import org.briarproject.briar.android.util.ActivityLaunchers.RequestBluetoothDiscoverable;
-
-import javax.inject.Inject;
-
-import androidx.activity.result.ActivityResultLauncher;
-import androidx.activity.result.contract.ActivityResultContracts.RequestPermission;
-import androidx.annotation.Nullable;
-import androidx.annotation.StringRes;
-import androidx.appcompat.app.AlertDialog;
-import androidx.fragment.app.DialogFragment;
-import androidx.lifecycle.ViewModelProvider;
-
-import static android.Manifest.permission.ACCESS_FINE_LOCATION;
-import static android.content.DialogInterface.BUTTON_POSITIVE;
-import static android.widget.Toast.LENGTH_LONG;
-import static java.util.Objects.requireNonNull;
-
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-public class BluetoothConnecterDialogFragment extends DialogFragment {
-
-	final static String TAG = BluetoothConnecterDialogFragment.class.getName();
-
-	@Inject
-	ViewModelProvider.Factory viewModelFactory;
-
-	private ConversationViewModel viewModel;
-	private BluetoothConnecter bluetoothConnecter;
-
-	private final ActivityResultLauncher<Integer> bluetoothDiscoverableRequest =
-			registerForActivityResult(new RequestBluetoothDiscoverable(),
-					this::onBluetoothDiscoverable);
-	private final ActivityResultLauncher<String> permissionRequest =
-			registerForActivityResult(new RequestPermission(),
-					this::onPermissionRequestResult);
-
-	@Override
-	public void onAttach(Context ctx) {
-		super.onAttach(ctx);
-		((BaseActivity) requireActivity()).getActivityComponent().inject(this);
-		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
-				.get(ConversationViewModel.class);
-		bluetoothConnecter = viewModel.getBluetoothConnecter();
-	}
-
-	@Override
-	public Dialog onCreateDialog(@Nullable Bundle savedInstanceState) {
-		Context ctx = requireContext();
-		return new AlertDialog.Builder(ctx, R.style.BriarDialogTheme)
-				.setTitle(R.string.dialog_title_connect_via_bluetooth)
-				.setMessage(R.string.dialog_message_connect_via_bluetooth)
-				// actual listener gets set in onResume()
-				.setPositiveButton(R.string.start, null)
-				.setNegativeButton(R.string.cancel, null)
-				.setCancelable(false) // keep it open until dismissed
-				.create();
-	}
-
-	@Override
-	public void onStart() {
-		super.onStart();
-		bluetoothConnecter.reset();
-		if (bluetoothConnecter.isBluetoothNotSupported()) {
-			showToast(R.string.toast_connect_via_bluetooth_error);
-			dismiss();
-			return;
-		}
-		// MenuItem only gets enabled after contactItem has loaded
-		ContactItem contact =
-				requireNonNull(viewModel.getContactItem().getValue());
-		ContactId contactId = contact.getContact().getId();
-		if (bluetoothConnecter.isConnectedViaBluetooth(contactId)) {
-			showToast(R.string.toast_connect_via_bluetooth_success);
-			dismiss();
-			return;
-		}
-		if (bluetoothConnecter.isDiscovering()) {
-			showToast(R.string.toast_connect_via_bluetooth_already_discovering);
-			dismiss();
-		}
-	}
-
-	@Override
-	public void onResume() {
-		super.onResume();
-		// Set the click listener for the START button here
-		// to prevent it from automatically dismissing the dialog.
-		// The dialog is shown in onStart(), so we set the listener here later.
-		AlertDialog dialog = (AlertDialog) getDialog();
-		Button positiveButton = dialog.getButton(BUTTON_POSITIVE);
-		positiveButton.setOnClickListener(this::onStartClicked);
-	}
-
-	private void onStartClicked(View v) {
-		// The dialog starts a permission request which comes back as true
-		// if the permission is already granted.
-		// So we can use the request as a generic entry point to the whole flow.
-		permissionRequest.launch(ACCESS_FINE_LOCATION);
-	}
-
-	private void onPermissionRequestResult(@Nullable Boolean result) {
-		Activity a = requireActivity();
-		// update permission result in BluetoothConnecter
-		bluetoothConnecter.onLocationPermissionResult(a, result);
-		// what to do when the user denies granting the location permission
-		Runnable onLocationPermissionDenied = () -> {
-			Toast.makeText(requireContext(),
-					R.string.toast_connect_via_bluetooth_no_location_permission,
-					LENGTH_LONG).show();
-			dismiss();
-		};
-		// if requirements are fulfilled, request Bluetooth discoverability
-		if (bluetoothConnecter.areRequirementsFulfilled(a, permissionRequest,
-				onLocationPermissionDenied)) {
-			bluetoothDiscoverableRequest.launch(120); // for 2min
-		}
-	}
-
-	private void onBluetoothDiscoverable(@Nullable Boolean result) {
-		if (result != null && result) {
-			// MenuItem only gets enabled after contactItem has loaded
-			ContactItem contact =
-					requireNonNull(viewModel.getContactItem().getValue());
-			bluetoothConnecter.onBluetoothDiscoverable(contact);
-			dismiss();
-		} else {
-			showToast(R.string.toast_connect_via_bluetooth_not_discoverable);
-		}
-	}
-
-	private void showToast(@StringRes int stringRes) {
-		Toast.makeText(requireContext(), stringRes, LENGTH_LONG).show();
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationActivity.java

@@ -48,6 +48,7 @@ import org.briarproject.briar.android.activity.BriarActivity;
 import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.android.attachment.AttachmentRetriever;
 import org.briarproject.briar.android.blog.BlogActivity;
+import org.briarproject.briar.android.contact.connect.ConnectViaBluetoothActivity;
 import org.briarproject.briar.android.conversation.ConversationVisitor.AttachmentCache;
 import org.briarproject.briar.android.conversation.ConversationVisitor.TextCache;
 import org.briarproject.briar.android.forum.ForumActivity;
@@ -104,7 +105,6 @@ import androidx.appcompat.widget.Toolbar;
 import androidx.core.app.ActivityCompat;
 import androidx.core.app.ActivityOptionsCompat;
 import androidx.core.content.ContextCompat;
-import androidx.fragment.app.FragmentManager;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.Observer;
 import androidx.lifecycle.ViewModelProvider;
@@ -379,9 +379,6 @@ public class ConversationActivity extends BriarActivity
 						this::showIntroductionOnboarding);
 			}
 		});
-		if (!featureFlags.shouldEnableConnectViaBluetooth()) {
-			menu.findItem(R.id.action_connect_via_bluetooth).setVisible(false);
-		}
 		// Transfer Data feature only supported on API 19+
 		if (SDK_INT >= 19 && featureFlags.shouldEnableTransferData()) {
 			menu.findItem(R.id.action_transfer_data).setVisible(true);
@@ -422,9 +419,9 @@ public class ConversationActivity extends BriarActivity
 			onAutoDeleteTimerNoticeClicked();
 			return true;
 		} else if (itemId == R.id.action_connect_via_bluetooth) {
-			FragmentManager fm = getSupportFragmentManager();
+			Intent intent = new Intent(this, ConnectViaBluetoothActivity.class);
-			new BluetoothConnecterDialogFragment().show(fm,
+			intent.putExtra(CONTACT_ID, contactId.getInt());
-					BluetoothConnecterDialogFragment.TAG);
+			startActivity(intent);
 			return true;
 		} else if (itemId == R.id.action_transfer_data) {
 			Intent intent = new Intent(this, RemovableDriveActivity.class);

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationViewModel.java

@@ -101,7 +101,6 @@ public class ConversationViewModel extends DbViewModel
 	private final AttachmentCreator attachmentCreator;
 	private final AutoDeleteManager autoDeleteManager;
 	private final ConversationManager conversationManager;
-	private final BluetoothConnecter bluetoothConnecter;
 
 	@Nullable
 	private ContactId contactId = null;
@@ -140,8 +139,7 @@ public class ConversationViewModel extends DbViewModel
 			AttachmentRetriever attachmentRetriever,
 			AttachmentCreator attachmentCreator,
 			AutoDeleteManager autoDeleteManager,
-			ConversationManager conversationManager,
+			ConversationManager conversationManager) {
-			BluetoothConnecter bluetoothConnecter) {
 		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
 		this.db = db;
 		this.eventBus = eventBus;
@@ -154,7 +152,6 @@ public class ConversationViewModel extends DbViewModel
 		this.attachmentCreator = attachmentCreator;
 		this.autoDeleteManager = autoDeleteManager;
 		this.conversationManager = conversationManager;
-		this.bluetoothConnecter = bluetoothConnecter;
 		messagingGroupId = map(contactItem, c ->
 				messagingManager.getContactGroup(c.getContact()).getId());
 		eventBus.addListener(this);
@@ -414,10 +411,6 @@ public class ConversationViewModel extends DbViewModel
 		return attachmentRetriever;
 	}
 
-	BluetoothConnecter getBluetoothConnecter() {
-		return bluetoothConnecter;
-	}
-
 	LiveData<ContactItem> getContactItem() {
 		return contactItem;
 	}

briar-android/src/main/java/org/briarproject/briar/android/fragment/FinalFragment.java

@@ -7,7 +7,6 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.Button;
 import android.widget.ImageView;
-import android.widget.ScrollView;
 import android.widget.TextView;
 
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
@@ -22,9 +21,11 @@ import androidx.annotation.StringRes;
 import androidx.appcompat.app.ActionBar;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.core.widget.ImageViewCompat;
+import androidx.core.widget.NestedScrollView;
 import androidx.fragment.app.Fragment;
 
 import static android.view.View.FOCUS_DOWN;
+import static android.view.View.GONE;
 
 /**
  * A fragment to be used at the end of a user flow
@@ -58,7 +59,7 @@ public class FinalFragment extends Fragment {
 		return f;
 	}
 
-	private ScrollView scrollView;
+	private NestedScrollView scrollView;
 	protected Button buttonView;
 
 	@Nullable
@@ -69,7 +70,7 @@ public class FinalFragment extends Fragment {
 		View v = inflater
 				.inflate(R.layout.fragment_final, container, false);
 
-		scrollView = (ScrollView) v;
+		scrollView = (NestedScrollView) v;
 		ImageView iconView = v.findViewById(R.id.iconView);
 		TextView titleView = v.findViewById(R.id.titleView);
 		TextView textView = v.findViewById(R.id.textView);
@@ -81,7 +82,12 @@ public class FinalFragment extends Fragment {
 		int color = getResources().getColor(args.getInt(ARG_ICON_TINT));
 		ColorStateList tint = ColorStateList.valueOf(color);
 		ImageViewCompat.setImageTintList(iconView, tint);
-		textView.setText(args.getInt(ARG_TEXT));
+		int textRes = args.getInt(ARG_TEXT);
+		if (textRes == 0) {
+			textView.setVisibility(GONE);
+		} else {
+			textView.setText(textRes);
+		}
 
 		buttonView.setOnClickListener(view -> onBackButtonPressed());
 

briar-android/src/main/java/org/briarproject/briar/android/hotspot/AbstractConditionManager.java

@@ -0,0 +1,84 @@
+package org.briarproject.briar.android.hotspot;
+
+import android.content.Context;
+import android.content.DialogInterface;
+import android.net.wifi.WifiManager;
+
+import org.briarproject.briar.R;
+
+import androidx.annotation.StringRes;
+import androidx.appcompat.app.AlertDialog;
+import androidx.core.util.Consumer;
+import androidx.fragment.app.FragmentActivity;
+
+import static android.content.Context.WIFI_SERVICE;
+
+/**
+ * Abstract base class for the ConditionManagers that ensure that the conditions
+ * to open a hotspot are fulfilled. There are different extensions of this for
+ * API levels lower than 29 and 29+.
+ */
+abstract class AbstractConditionManager {
+
+	enum Permission {
+		UNKNOWN, GRANTED, SHOW_RATIONALE, PERMANENTLY_DENIED
+	}
+
+	protected final Consumer<Boolean> permissionUpdateCallback;
+	protected FragmentActivity ctx;
+	WifiManager wifiManager;
+
+	AbstractConditionManager(Consumer<Boolean> permissionUpdateCallback) {
+		this.permissionUpdateCallback = permissionUpdateCallback;
+	}
+
+	/**
+	 * Pass a FragmentActivity context here during `onCreateView()`.
+	 */
+	void init(FragmentActivity ctx) {
+		this.ctx = ctx;
+		this.wifiManager = (WifiManager) ctx.getApplicationContext()
+				.getSystemService(WIFI_SERVICE);
+	}
+
+	/**
+	 * Call this during onStart() in the fragment where the ConditionManager
+	 * is used.
+	 */
+	abstract void onStart();
+
+	/**
+	 * Check if all required conditions are met such that the hotspot can be
+	 * started. If any precondition is not met yet, bring up relevant dialogs
+	 * asking the user to grant relevant permissions or take relevant actions.
+	 *
+	 * @return true if conditions are fulfilled and flow can continue.
+	 */
+	abstract boolean checkAndRequestConditions();
+
+	void showDenialDialog(FragmentActivity ctx,
+			@StringRes int title, @StringRes int body,
+			DialogInterface.OnClickListener onOkClicked, Runnable onDismiss) {
+		AlertDialog.Builder builder = new AlertDialog.Builder(ctx);
+		builder.setTitle(title);
+		builder.setMessage(body);
+		builder.setPositiveButton(R.string.ok, onOkClicked);
+		builder.setNegativeButton(R.string.cancel,
+				(dialog, which) -> ctx.supportFinishAfterTransition());
+		builder.setOnDismissListener(dialog -> onDismiss.run());
+		builder.show();
+	}
+
+	void showRationale(Context ctx, @StringRes int title,
+			@StringRes int body, Runnable onContinueClicked,
+			Runnable onDismiss) {
+		AlertDialog.Builder builder = new AlertDialog.Builder(ctx);
+		builder.setTitle(title);
+		builder.setMessage(body);
+		builder.setNeutralButton(R.string.continue_button,
+				(dialog, which) -> onContinueClicked.run());
+		builder.setOnDismissListener(dialog -> onDismiss.run());
+		builder.show();
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/hotspot/AbstractTabsFragment.java

@@ -9,6 +9,7 @@ import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.Button;
+import android.widget.TextView;
 
 import com.google.android.material.tabs.TabLayout;
 import com.google.android.material.tabs.TabLayoutMediator;
@@ -43,6 +44,7 @@ public abstract class AbstractTabsFragment extends Fragment {
 
 	protected Button stopButton;
 	protected Button connectedButton;
+	protected TextView connectedView;
 
 	@Override
 	public void onAttach(Context context) {
@@ -85,6 +87,9 @@ public abstract class AbstractTabsFragment extends Fragment {
 			finishAfterTransition(requireActivity());
 		});
 		connectedButton = view.findViewById(R.id.connectedButton);
+		connectedView = view.findViewById(R.id.connectedView);
+		viewModel.getPeersConnectedEvent()
+				.observe(getViewLifecycleOwner(), this::onPeerConnected);
 	}
 
 	@Override
@@ -126,4 +131,13 @@ public abstract class AbstractTabsFragment extends Fragment {
 		}
 	}
 
+	private void onPeerConnected(int peers) {
+		if (peers == 0) {
+			connectedView.setText(R.string.hotspot_no_peers_connected);
+		} else {
+			connectedView.setText(getResources().getQuantityString(
+					R.plurals.hotspot_peers_connected, peers, peers));
+		}
+	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/hotspot/ConditionManager.java

@@ -1,171 +1,83 @@
 package org.briarproject.briar.android.hotspot;
 
-import android.content.DialogInterface.OnClickListener;
 import android.content.Intent;
-import android.net.wifi.WifiManager;
 import android.provider.Settings;
 
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
 
-import androidx.activity.result.ActivityResult;
+import java.util.logging.Logger;
-import androidx.activity.result.ActivityResultLauncher;
-import androidx.annotation.Nullable;
-import androidx.annotation.StringRes;
-import androidx.appcompat.app.AlertDialog;
-import androidx.fragment.app.FragmentActivity;
 
-import static android.Manifest.permission.ACCESS_FINE_LOCATION;
+import androidx.activity.result.ActivityResultCaller;
-import static android.content.Context.WIFI_SERVICE;
+import androidx.activity.result.ActivityResultLauncher;
-import static android.os.Build.VERSION.SDK_INT;
+import androidx.activity.result.contract.ActivityResultContracts.StartActivityForResult;
-import static androidx.core.app.ActivityCompat.shouldShowRequestPermissionRationale;
+import androidx.core.util.Consumer;
-import static org.briarproject.briar.android.util.UiUtils.getGoToSettingsListener;
+
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Logger.getLogger;
 
 /**
- * This class ensures that the conditions to open a hotspot are fulfilled.
+ * This class ensures that the conditions to open a hotspot are fulfilled on
- * <p>
+ * API levels < 29.
- * Be sure to call {@link #onRequestPermissionResult(Boolean)} and
- * {@link #onRequestWifiEnabledResult()} when you get the
- * {@link ActivityResult}.
  * <p>
  * As soon as {@link #checkAndRequestConditions()} returns true,
  * all conditions are fulfilled.
  */
-@NotNullByDefault
+class ConditionManager extends AbstractConditionManager {
-class ConditionManager {
 
-	private enum Permission {
+	private static final Logger LOG =
-		UNKNOWN, GRANTED, SHOW_RATIONALE, PERMANENTLY_DENIED
+			getLogger(ConditionManager.class.getName());
-	}
 
-	private Permission locationPermission = Permission.UNKNOWN;
-	private Permission wifiSetting = Permission.SHOW_RATIONALE;
-
-	private final FragmentActivity ctx;
-	private final WifiManager wifiManager;
-	private final ActivityResultLauncher<String> locationRequest;
 	private final ActivityResultLauncher<Intent> wifiRequest;
 
-	ConditionManager(FragmentActivity ctx,
+	ConditionManager(ActivityResultCaller arc,
-			ActivityResultLauncher<String> locationRequest,
+			Consumer<Boolean> permissionUpdateCallback) {
-			ActivityResultLauncher<Intent> wifiRequest) {
+		super(permissionUpdateCallback);
-		this.ctx = ctx;
+		wifiRequest = arc.registerForActivityResult(
-		this.wifiManager = (WifiManager) ctx.getApplicationContext()
+				new StartActivityForResult(),
-				.getSystemService(WIFI_SERVICE);
+				result -> permissionUpdateCallback
-		this.locationRequest = locationRequest;
+						.accept(wifiManager.isWifiEnabled()));
-		this.wifiRequest = wifiRequest;
 	}
 
-	/**
+	@Override
-	 * Call this to reset state when UI starts,
+	void onStart() {
-	 * because state might have changed.
+		// nothing to do here
-	 */
-	void resetPermissions() {
-		locationPermission = Permission.UNKNOWN;
-		wifiSetting = Permission.SHOW_RATIONALE;
-	}
-
-	/**
-	 * This makes a request for location permission.
-	 * If {@link #checkAndRequestConditions()} returns true, you can continue.
-	 */
-	void startConditionChecks() {
-		locationRequest.launch(ACCESS_FINE_LOCATION);
-	}
-
-	/**
-	 * @return true if conditions are fulfilled and flow can continue.
-	 */
-	boolean checkAndRequestConditions() {
-		if (areEssentialPermissionsGranted()) return true;
-
-		// If an essential permission has been permanently denied, ask the
-		// user to change the setting
-		if (locationPermission == Permission.PERMANENTLY_DENIED) {
-			showDenialDialog(R.string.permission_location_title,
-					R.string.permission_hotspot_location_denied_body,
-					getGoToSettingsListener(ctx));
-			return false;
-		}
-		if (wifiSetting == Permission.PERMANENTLY_DENIED) {
-			showDenialDialog(R.string.wifi_settings_title,
-					R.string.wifi_settings_request_denied_body,
-					(d, w) -> requestEnableWiFi());
-			return false;
-		}
-
-		// Should we show the rationale for location permission or Wi-Fi?
-		if (locationPermission == Permission.SHOW_RATIONALE) {
-			showRationale(R.string.permission_location_title,
-					R.string.permission_hotspot_location_request_body,
-					this::requestPermissions);
-		} else if (wifiSetting == Permission.SHOW_RATIONALE) {
-			showRationale(R.string.wifi_settings_title,
-					R.string.wifi_settings_request_enable_body,
-					this::requestEnableWiFi);
-		}
-		return false;
-	}
-
-	void onRequestPermissionResult(@Nullable Boolean granted) {
-		if (granted != null && granted) {
-			locationPermission = Permission.GRANTED;
-		} else if (shouldShowRequestPermissionRationale(ctx,
-				ACCESS_FINE_LOCATION)) {
-			locationPermission = Permission.SHOW_RATIONALE;
-		} else {
-			locationPermission = Permission.PERMANENTLY_DENIED;
-		}
-	}
-
-	void onRequestWifiEnabledResult() {
-		wifiSetting = wifiManager.isWifiEnabled() ? Permission.GRANTED :
-				Permission.PERMANENTLY_DENIED;
 	}
 
 	private boolean areEssentialPermissionsGranted() {
-		if (SDK_INT < 29) {
+		if (LOG.isLoggable(INFO)) {
-			if (!wifiManager.isWifiEnabled()) {
+			LOG.info(String.format("areEssentialPermissionsGranted(): " +
-				//noinspection deprecation
+							"wifiManager.isWifiEnabled()? %b",
-				return wifiManager.setWifiEnabled(true);
+					wifiManager.isWifiEnabled()));
-			}
-			return true;
-		} else {
-			return locationPermission == Permission.GRANTED
-					&& wifiManager.isWifiEnabled();
 		}
+		return wifiManager.isWifiEnabled();
 	}
 
-	private void showDenialDialog(@StringRes int title, @StringRes int body,
+	@Override
-			OnClickListener onOkClicked) {
+	boolean checkAndRequestConditions() {
-		AlertDialog.Builder builder = new AlertDialog.Builder(ctx);
+		if (areEssentialPermissionsGranted()) return true;
-		builder.setTitle(title);
-		builder.setMessage(body);
-		builder.setPositiveButton(R.string.ok, onOkClicked);
-		builder.setNegativeButton(R.string.cancel,
-				(dialog, which) -> ctx.supportFinishAfterTransition());
-		builder.show();
-	}
 
-	private void showRationale(@StringRes int title, @StringRes int body,
+		if (!wifiManager.isWifiEnabled()) {
-			Runnable onContinueClicked) {
+			// Try enabling the Wifi and return true if that seems to have been
-		AlertDialog.Builder builder = new AlertDialog.Builder(ctx);
+			// successful, i.e. "Wifi is either already in the requested state, or
-		builder.setTitle(title);
+			// in progress toward the requested state".
-		builder.setMessage(body);
+			if (wifiManager.setWifiEnabled(true)) {
-		builder.setNeutralButton(R.string.continue_button,
+				LOG.info("Enabled wifi");
-				(dialog, which) -> onContinueClicked.run());
+				return true;
-		builder.show();
+			}
-	}
 
-	private void requestPermissions() {
+			// Wifi is not enabled and we can't seem to enable it, so ask the user
-		locationRequest.launch(ACCESS_FINE_LOCATION);
+			// to enable it for us.
+			showRationale(ctx, R.string.wifi_settings_title,
+					R.string.wifi_settings_request_enable_body,
+					this::requestEnableWiFi,
+					() -> permissionUpdateCallback.accept(false));
+		}
+
+		return false;
 	}
 
 	private void requestEnableWiFi() {
-		Intent i = SDK_INT < 29 ?
+		wifiRequest.launch(new Intent(Settings.ACTION_WIFI_SETTINGS));
-				new Intent(Settings.ACTION_WIFI_SETTINGS) :
-				new Intent(Settings.Panel.ACTION_WIFI);
-		wifiRequest.launch(i);
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/hotspot/ConditionManager29.java

@@ -0,0 +1,136 @@
+package org.briarproject.briar.android.hotspot;
+
+import android.content.Intent;
+import android.provider.Settings;
+
+import org.briarproject.briar.R;
+
+import java.util.logging.Logger;
+
+import androidx.activity.result.ActivityResultCaller;
+import androidx.activity.result.ActivityResultLauncher;
+import androidx.activity.result.contract.ActivityResultContracts.RequestPermission;
+import androidx.activity.result.contract.ActivityResultContracts.StartActivityForResult;
+import androidx.annotation.Nullable;
+import androidx.annotation.RequiresApi;
+import androidx.core.util.Consumer;
+
+import static android.Manifest.permission.ACCESS_FINE_LOCATION;
+import static androidx.core.app.ActivityCompat.shouldShowRequestPermissionRationale;
+import static java.lang.Boolean.TRUE;
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.briar.android.util.UiUtils.getGoToSettingsListener;
+
+/**
+ * This class ensures that the conditions to open a hotspot are fulfilled on
+ * API levels >= 29.
+ * <p>
+ * As soon as {@link #checkAndRequestConditions()} returns true,
+ * all conditions are fulfilled.
+ */
+@RequiresApi(29)
+class ConditionManager29 extends AbstractConditionManager {
+
+	private static final Logger LOG =
+			getLogger(ConditionManager29.class.getName());
+
+	private Permission locationPermission = Permission.UNKNOWN;
+
+	private final ActivityResultLauncher<String> locationRequest;
+	private final ActivityResultLauncher<Intent> wifiRequest;
+
+	ConditionManager29(ActivityResultCaller arc,
+			Consumer<Boolean> permissionUpdateCallback) {
+		super(permissionUpdateCallback);
+		locationRequest = arc.registerForActivityResult(
+				new RequestPermission(), granted -> {
+					onRequestPermissionResult(granted);
+					permissionUpdateCallback.accept(TRUE.equals(granted));
+				});
+		wifiRequest = arc.registerForActivityResult(
+				new StartActivityForResult(),
+				result -> permissionUpdateCallback
+						.accept(wifiManager.isWifiEnabled())
+		);
+	}
+
+	@Override
+	void onStart() {
+		locationPermission = Permission.UNKNOWN;
+	}
+
+	private boolean areEssentialPermissionsGranted() {
+		boolean isWifiEnabled = wifiManager.isWifiEnabled();
+		if (LOG.isLoggable(INFO)) {
+			LOG.info(String.format("areEssentialPermissionsGranted(): " +
+							"locationPermission? %s, " +
+							"wifiManager.isWifiEnabled()? %b",
+					locationPermission, isWifiEnabled));
+		}
+		return locationPermission == Permission.GRANTED && isWifiEnabled;
+	}
+
+	@Override
+	boolean checkAndRequestConditions() {
+		if (areEssentialPermissionsGranted()) return true;
+
+		if (locationPermission == Permission.UNKNOWN) {
+			locationRequest.launch(ACCESS_FINE_LOCATION);
+			return false;
+		}
+
+		// If the location permission has been permanently denied, ask the
+		// user to change the setting
+		if (locationPermission == Permission.PERMANENTLY_DENIED) {
+			showDenialDialog(ctx, R.string.permission_location_title,
+					R.string.permission_hotspot_location_denied_body,
+					getGoToSettingsListener(ctx),
+					() -> permissionUpdateCallback.accept(false));
+			return false;
+		}
+
+		// Should we show the rationale for location permission?
+		if (locationPermission == Permission.SHOW_RATIONALE) {
+			showRationale(ctx, R.string.permission_location_title,
+					R.string.permission_hotspot_location_request_body,
+					this::requestPermissions,
+					() -> permissionUpdateCallback.accept(false));
+			return false;
+		}
+
+		// If Wifi is not enabled, we show the rationale for enabling Wifi?
+		if (!wifiManager.isWifiEnabled()) {
+			showRationale(ctx, R.string.wifi_settings_title,
+					R.string.wifi_settings_request_enable_body,
+					this::requestEnableWiFi,
+					() -> permissionUpdateCallback.accept(false));
+			return false;
+		}
+
+		// we shouldn't usually reach this point, but if we do, return false
+		// anyway to force a recheck. Maybe some condition changed in the
+		// meantime.
+		return false;
+	}
+
+	private void onRequestPermissionResult(@Nullable Boolean granted) {
+		if (granted != null && granted) {
+			locationPermission = Permission.GRANTED;
+		} else if (shouldShowRequestPermissionRationale(ctx,
+				ACCESS_FINE_LOCATION)) {
+			locationPermission = Permission.SHOW_RATIONALE;
+		} else {
+			locationPermission = Permission.PERMANENTLY_DENIED;
+		}
+	}
+
+	private void requestPermissions() {
+		locationRequest.launch(ACCESS_FINE_LOCATION);
+	}
+
+	private void requestEnableWiFi() {
+		wifiRequest.launch(new Intent(Settings.Panel.ACTION_WIFI));
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/hotspot/FallbackFragment.java

@@ -15,6 +15,7 @@ import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.fragment.BaseFragment;
+import org.briarproject.briar.android.util.ActivityLaunchers.CreateDocumentAdvanced;
 
 import java.util.List;
 
@@ -22,7 +23,6 @@ import javax.inject.Inject;
 
 import androidx.activity.result.ActivityResultLauncher;
 import androidx.annotation.Nullable;
-import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentActivity;
 import androidx.lifecycle.ViewModelProvider;
 
@@ -33,12 +33,10 @@ import static android.content.pm.PackageManager.MATCH_DEFAULT_ONLY;
 import static android.os.Build.VERSION.SDK_INT;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
-import static androidx.activity.result.contract.ActivityResultContracts.CreateDocument;
 import static androidx.transition.TransitionManager.beginDelayedTransition;
 import static org.briarproject.briar.android.AppModule.getAndroidComponent;
 import static org.briarproject.briar.android.hotspot.HotspotViewModel.getApkFileName;
 
-
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class FallbackFragment extends BaseFragment {
@@ -50,7 +48,7 @@ public class FallbackFragment extends BaseFragment {
 
 	private HotspotViewModel viewModel;
 	private final ActivityResultLauncher<String> launcher =
-			registerForActivityResult(new CreateDocument(),
+			registerForActivityResult(new CreateDocumentAdvanced(),
 					this::onDocumentCreated);
 	private Button fallbackButton;
 	private ProgressBar progressBar;
@@ -75,7 +73,7 @@ public class FallbackFragment extends BaseFragment {
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 		return inflater
-				.inflate(R.layout.fragment_hotspot_save_apk, container, false);
+				.inflate(R.layout.fragment_hotspot_fallback, container, false);
 	}
 
 	@Override
@@ -92,8 +90,7 @@ public class FallbackFragment extends BaseFragment {
 			if (SDK_INT >= 19) launcher.launch(getApkFileName());
 			else viewModel.exportApk();
 		});
-		viewModel.getSavedApkToUri()
+		viewModel.getSavedApkToUri().observeEvent(this, this::shareUri);
-				.observeEvent(this, uri -> shareUri(this, uri));
 	}
 
 	private void onDocumentCreated(@Nullable Uri uri) {
@@ -107,12 +104,12 @@ public class FallbackFragment extends BaseFragment {
 		progressBar.setVisibility(INVISIBLE);
 	}
 
-	static void shareUri(Fragment fragment, Uri uri) {
+	void shareUri(Uri uri) {
 		Intent i = new Intent(ACTION_SEND);
 		i.putExtra(EXTRA_STREAM, uri);
 		i.setType("*/*"); // gives us all sharing options
 		i.addFlags(FLAG_GRANT_READ_URI_PERMISSION);
-		Context ctx = fragment.requireContext();
+		Context ctx = requireContext();
 		if (SDK_INT <= 19) {
 			// Workaround for Android bug:
 			// ctx.grantUriPermission also needed for Android 4
@@ -124,7 +121,7 @@ public class FallbackFragment extends BaseFragment {
 						FLAG_GRANT_READ_URI_PERMISSION);
 			}
 		}
-		fragment.startActivity(Intent.createChooser(i, null));
+		startActivity(Intent.createChooser(i, null));
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/hotspot/HotspotActivity.java

@@ -59,12 +59,13 @@ public class HotspotActivity extends BriarActivity
 				// check if fragment is already added
 				// to not lose state on configuration changes
 				if (fm.findFragmentByTag(tag) == null) {
-					if (!started.consume()) {
+					if (started.wasNotYetConsumed()) {
+						started.consume();
 						showFragment(fm, new HotspotFragment(), tag);
 					}
 				}
 			} else if (hotspotState instanceof HotspotError) {
-				HotspotError error = ((HotspotError) hotspotState);
+				HotspotError error = (HotspotError) hotspotState;
 				showErrorFragment(error.getError());
 			}
 		});

briar-android/src/main/java/org/briarproject/briar/android/hotspot/HotspotFragment.java

@@ -3,12 +3,8 @@ package org.briarproject.briar.android.hotspot;
 import android.os.Bundle;
 import android.view.View;
 
-import com.google.android.material.snackbar.Snackbar;
-
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.briar.R;
-import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 
 import androidx.annotation.Nullable;
 import androidx.fragment.app.Fragment;
@@ -25,8 +21,6 @@ public class HotspotFragment extends AbstractTabsFragment {
 	public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
 		super.onViewCreated(view, savedInstanceState);
 		connectedButton.setOnClickListener(v -> showNextFragment());
-		viewModel.getPeerConnectedEvent().observeEvent(getViewLifecycleOwner(),
-				this::onPeerConnected);
 	}
 
 	@Override
@@ -39,17 +33,6 @@ public class HotspotFragment extends AbstractTabsFragment {
 		return QrHotspotFragment.newInstance(true);
 	}
 
-	private void onPeerConnected(boolean connected) {
-		if (!connected) return;
-		new BriarSnackbarBuilder()
-				.setAction(R.string.hotspot_peer_connected_action, v ->
-						showNextFragment())
-				.make(connectedButton, R.string.hotspot_peer_connected,
-						Snackbar.LENGTH_LONG)
-				.setAnchorView(connectedButton)
-				.show();
-	}
-
 	private void showNextFragment() {
 		Fragment f = new WebsiteFragment();
 		String tag = WebsiteFragment.TAG;

briar-android/src/main/java/org/briarproject/briar/android/hotspot/HotspotIntroFragment.java

@@ -1,7 +1,6 @@
 package org.briarproject.briar.android.hotspot;
 
 import android.content.Context;
-import android.content.Intent;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageManager;
 import android.os.Bundle;
@@ -10,6 +9,7 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.Button;
 import android.widget.ProgressBar;
+import android.widget.ScrollView;
 import android.widget.TextView;
 
 import com.google.android.material.snackbar.Snackbar;
@@ -20,15 +20,14 @@ import org.briarproject.briar.R;
 
 import javax.inject.Inject;
 
-import androidx.activity.result.ActivityResultLauncher;
-import androidx.activity.result.contract.ActivityResultContracts.RequestPermission;
-import androidx.activity.result.contract.ActivityResultContracts.StartActivityForResult;
 import androidx.annotation.Nullable;
 import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentActivity;
 import androidx.lifecycle.ViewModelProvider;
 
 import static android.content.pm.ApplicationInfo.FLAG_TEST_ONLY;
+import static android.os.Build.VERSION.SDK_INT;
+import static android.view.View.FOCUS_DOWN;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 import static androidx.transition.TransitionManager.beginDelayedTransition;
@@ -45,22 +44,15 @@ public class HotspotIntroFragment extends Fragment {
 	ViewModelProvider.Factory viewModelFactory;
 
 	private HotspotViewModel viewModel;
-	private ConditionManager conditionManager;
 
 	private Button startButton;
 	private ProgressBar progressBar;
 	private TextView progressTextView;
+	private ScrollView scrollView;
 
-	private final ActivityResultLauncher<String> locationRequest =
+	private final AbstractConditionManager conditionManager = SDK_INT < 29 ?
-			registerForActivityResult(new RequestPermission(), granted -> {
+			new ConditionManager(this, this::onPermissionUpdate) :
-				conditionManager.onRequestPermissionResult(granted);
+			new ConditionManager29(this, this::onPermissionUpdate);
-				startHotspot();
-			});
-	private final ActivityResultLauncher<Intent> wifiRequest =
-			registerForActivityResult(new StartActivityForResult(), result -> {
-				conditionManager.onRequestWifiEnabledResult();
-				startHotspot();
-			});
 
 	@Override
 	public void onAttach(Context context) {
@@ -69,8 +61,6 @@ public class HotspotIntroFragment extends Fragment {
 		getAndroidComponent(activity).inject(this);
 		viewModel = new ViewModelProvider(activity, viewModelFactory)
 				.get(HotspotViewModel.class);
-		conditionManager =
-				new ConditionManager(activity, locationRequest, wifiRequest);
 	}
 
 	@Override
@@ -83,11 +73,11 @@ public class HotspotIntroFragment extends Fragment {
 		startButton = v.findViewById(R.id.startButton);
 		progressBar = v.findViewById(R.id.progressBar);
 		progressTextView = v.findViewById(R.id.progressTextView);
+		scrollView = v.findViewById(R.id.scrollView);
 
-		startButton.setOnClickListener(button -> {
+		startButton.setOnClickListener(this::onButtonClick);
-			startButton.setEnabled(false);
+
-			conditionManager.startConditionChecks();
+		conditionManager.init(requireActivity());
-		});
 
 		return v;
 	}
@@ -95,11 +85,17 @@ public class HotspotIntroFragment extends Fragment {
 	@Override
 	public void onStart() {
 		super.onStart();
-		conditionManager.resetPermissions();
+		conditionManager.onStart();
+		// Scroll down in case the screen is small, so the button is visible
+		scrollView.post(() -> scrollView.fullScroll(FOCUS_DOWN));
 	}
 
-	private void startHotspot() {
+	private void onButtonClick(View view) {
-		startButton.setEnabled(true);
+		startButton.setEnabled(false);
+		startHotspotIfConditionsFulfilled();
+	}
+
+	private void startHotspotIfConditionsFulfilled() {
 		if (conditionManager.checkAndRequestConditions()) {
 			showInstallWarningIfNeeded();
 			beginDelayedTransition((ViewGroup) requireView());
@@ -110,6 +106,13 @@ public class HotspotIntroFragment extends Fragment {
 		}
 	}
 
+	private void onPermissionUpdate(boolean recheckPermissions) {
+		startButton.setEnabled(true);
+		if (recheckPermissions) {
+			startHotspotIfConditionsFulfilled();
+		}
+	}
+
 	private void showInstallWarningIfNeeded() {
 		Context ctx = requireContext();
 		ApplicationInfo applicationInfo;

briar-android/src/main/java/org/briarproject/briar/android/hotspot/HotspotManager.java

@@ -1,5 +1,6 @@
 package org.briarproject.briar.android.hotspot;
 
+import android.annotation.SuppressLint;
 import android.app.Application;
 import android.content.Context;
 import android.graphics.Bitmap;
@@ -10,6 +11,7 @@ import android.net.wifi.p2p.WifiP2pManager;
 import android.net.wifi.p2p.WifiP2pManager.ActionListener;
 import android.net.wifi.p2p.WifiP2pManager.GroupInfoListener;
 import android.os.Handler;
+import android.os.PowerManager;
 import android.util.DisplayMetrics;
 
 import org.briarproject.bramble.api.db.DatabaseExecutor;
@@ -34,6 +36,7 @@ import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
 import androidx.annotation.UiThread;
 
+import static android.content.Context.POWER_SERVICE;
 import static android.content.Context.WIFI_P2P_SERVICE;
 import static android.content.Context.WIFI_SERVICE;
 import static android.net.wifi.WifiManager.WIFI_MODE_FULL;
@@ -44,30 +47,35 @@ import static android.net.wifi.p2p.WifiP2pManager.ERROR;
 import static android.net.wifi.p2p.WifiP2pManager.NO_SERVICE_REQUESTS;
 import static android.net.wifi.p2p.WifiP2pManager.P2P_UNSUPPORTED;
 import static android.os.Build.VERSION.SDK_INT;
+import static android.os.PowerManager.FULL_WAKE_LOCK;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.INFO;
+import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.briar.android.util.QrCodeUtils.HOTSPOT_QRCODE_FACTOR;
 import static org.briarproject.briar.android.util.UiUtils.handleException;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class HotspotManager implements ActionListener {
+class HotspotManager {
 
 	interface HotspotListener {
+		@UiThread
 		void onStartingHotspot();
 
 		@IoExecutor
 		void onHotspotStarted(NetworkConfig networkConfig);
 
 		@UiThread
-		void onDeviceConnected();
+		void onPeersUpdated(int peers);
-
-		void onHotspotStopped();
 
+		@UiThread
 		void onHotspotError(String error);
 	}
 
 	private static final Logger LOG = getLogger(HotspotManager.class.getName());
 
+	private static final int MAX_FRAMEWORK_ATTEMPTS = 5;
 	private static final int MAX_GROUP_INFO_ATTEMPTS = 5;
 	private static final int RETRY_DELAY_MILLIS = 1000;
 	private static final String HOTSPOT_NAMESPACE = "hotspot";
@@ -84,14 +92,17 @@ class HotspotManager implements ActionListener {
 	private final SecureRandom random;
 	private final WifiManager wifiManager;
 	private final WifiP2pManager wifiP2pManager;
+	private final PowerManager powerManager;
 	private final Handler handler;
 	private final String lockTag;
 
 	private HotspotListener listener;
 	private WifiManager.WifiLock wifiLock;
+	private PowerManager.WakeLock wakeLock;
 	private WifiP2pManager.Channel channel;
+	@Nullable
 	@RequiresApi(29)
-	private volatile NetworkConfig savedNetworkConfig;
+	private volatile NetworkConfig savedNetworkConfig = null;
 
 	@Inject
 	HotspotManager(Application ctx,
@@ -110,6 +121,7 @@ class HotspotManager implements ActionListener {
 				.getSystemService(WIFI_SERVICE);
 		wifiP2pManager =
 				(WifiP2pManager) ctx.getSystemService(WIFI_P2P_SERVICE);
+		powerManager = (PowerManager) ctx.getSystemService(POWER_SERVICE);
 		handler = new Handler(ctx.getMainLooper());
 		lockTag = ctx.getPackageName() + ":app-sharing-hotspot";
 	}
@@ -126,30 +138,106 @@ class HotspotManager implements ActionListener {
 			return;
 		}
 		listener.onStartingHotspot();
+		acquireLocks();
+		startWifiP2pFramework(1);
+	}
+
+	/**
+	 * As soon as Wifi is enabled, we try starting the WifiP2p framework.
+	 * If Wifi has just been enabled, it is possible that will fail. If that
+	 * happens we try again for MAX_FRAMEWORK_ATTEMPTS times after a delay of
+	 * RETRY_DELAY_MILLIS after each attempt.
+	 * <p>
+	 * Rationale: it can take a few milliseconds for WifiP2p to become available
+	 * after enabling Wifi. Depending on the API level it is possible to check this
+	 * using {@link WifiP2pManager#requestP2pState} or register a BroadcastReceiver
+	 * on the WIFI_P2P_STATE_CHANGED_ACTION to get notified when WifiP2p is really
+	 * available. Trying to implement a solution that works reliably using these
+	 * checks turned out to be a long rabbit-hole with lots of corner cases and
+	 * workarounds for specific situations.
+	 * Instead we now rely on this trial-and-error approach of just starting
+	 * the framework and retrying if it fails.
+	 * <p>
+	 * We'll realize that the framework is busy when the ActionListener passed
+	 * to {@link WifiP2pManager#createGroup} is called with onFailure(BUSY)
+	 */
+	@UiThread
+	private void startWifiP2pFramework(int attempt) {
+		if (LOG.isLoggable(INFO)) {
+			LOG.info("startWifiP2pFramework attempt: " + attempt);
+		}
+		/*
+		 * It is important that we call WifiP2pManager#initialize again
+		 * for every attempt to starting the framework because otherwise,
+		 * createGroup() will continue to fail with a BUSY state.
+		 */
 		channel = wifiP2pManager.initialize(ctx, ctx.getMainLooper(), null);
 		if (channel == null) {
-			listener.onHotspotError(
+			releaseHotspotWithError(
 					ctx.getString(R.string.hotspot_error_no_wifi_direct));
 			return;
 		}
+
+		ActionListener listener = new ActionListener() {
+			@Override
+			// Callback for wifiP2pManager#createGroup() during startWifiP2pHotspot()
+			public void onSuccess() {
+				requestGroupInfo(1);
+			}
+
+			@Override
+			// Callback for wifiP2pManager#createGroup() during startWifiP2pHotspot()
+			public void onFailure(int reason) {
+				if (LOG.isLoggable(INFO)) {
+					LOG.info("onFailure: " + reason);
+				}
+				if (reason == BUSY) {
+					// WifiP2p not ready yet or hotspot already running
+					restartWifiP2pFramework(attempt);
+				} else if (reason == P2P_UNSUPPORTED) {
+					releaseHotspotWithError(ctx.getString(
+							R.string.hotspot_error_start_callback_failed,
+							"p2p unsupported"));
+				} else if (reason == ERROR) {
+					releaseHotspotWithError(ctx.getString(
+							R.string.hotspot_error_start_callback_failed,
+							"p2p error"));
+				} else if (reason == NO_SERVICE_REQUESTS) {
+					releaseHotspotWithError(ctx.getString(
+							R.string.hotspot_error_start_callback_failed,
+							"no service requests"));
+				} else {
+					// all cases covered, in doubt set to error
+					releaseHotspotWithError(ctx.getString(
+							R.string.hotspot_error_start_callback_failed_unknown,
+							reason));
+				}
+			}
+		};
+
 		try {
 			if (SDK_INT >= 29) {
-				dbExecutor.execute(() -> {
+				Runnable createGroup = () -> {
+					NetworkConfig c = requireNonNull(savedNetworkConfig);
+					WifiP2pConfig config = new WifiP2pConfig.Builder()
+							.setGroupOperatingBand(GROUP_OWNER_BAND_2GHZ)
+							.setNetworkName(c.ssid)
+							.setPassphrase(c.password)
+							.build();
+					wifiP2pManager.createGroup(channel, config, listener);
+				};
+				if (savedNetworkConfig == null) {
 					// load savedNetworkConfig before starting hotspot
-					loadSavedNetworkConfig();
+					dbExecutor.execute(() -> {
-					androidExecutor.runOnUiThread(() -> {
+						loadSavedNetworkConfig();
-						WifiP2pConfig config = new WifiP2pConfig.Builder()
+						androidExecutor.runOnUiThread(createGroup);
-								.setGroupOperatingBand(GROUP_OWNER_BAND_2GHZ)
-								.setNetworkName(savedNetworkConfig.ssid)
-								.setPassphrase(savedNetworkConfig.password)
-								.build();
-						acquireLock();
-						wifiP2pManager.createGroup(channel, config, this);
 					});
-				});
+				} else {
+					// savedNetworkConfig was already loaded, create group now
+					createGroup.run();
+				}
 			} else {
-				acquireLock();
+				wifiP2pManager.createGroup(channel, listener);
-				wifiP2pManager.createGroup(channel, this);
 			}
 		} catch (SecurityException e) {
 			// this should never happen, because we request permissions before
@@ -157,54 +245,45 @@ class HotspotManager implements ActionListener {
 		}
 	}
 
-	@Override
+	@UiThread
-	// Callback for wifiP2pManager#createGroup() during startWifiP2pHotspot()
+	private void restartWifiP2pFramework(int attempt) {
-	public void onSuccess() {
+		LOG.info("retrying to start WifiP2p framework");
-		requestGroupInfo(1);
+		if (attempt < MAX_FRAMEWORK_ATTEMPTS) {
-	}
+			if (SDK_INT >= 27 && channel != null) channel.close();
-
+			channel = null;
-	@Override
+			handler.postDelayed(() -> startWifiP2pFramework(attempt + 1),
-	// Callback for wifiP2pManager#createGroup() during startWifiP2pHotspot()
+					RETRY_DELAY_MILLIS);
-	public void onFailure(int reason) {
-		if (reason == BUSY) {
-			// Hotspot already running
-			requestGroupInfo(1);
-		} else if (reason == P2P_UNSUPPORTED) {
-			releaseHotspotWithError(ctx.getString(
-					R.string.hotspot_error_start_callback_failed,
-					"p2p unsupported"));
-		} else if (reason == ERROR) {
-			releaseHotspotWithError(ctx.getString(
-					R.string.hotspot_error_start_callback_failed, "p2p error"));
-		} else if (reason == NO_SERVICE_REQUESTS) {
-			releaseHotspotWithError(ctx.getString(
-					R.string.hotspot_error_start_callback_failed,
-					"no service requests"));
 		} else {
-			// all cases covered, in doubt set to error
+			releaseHotspotWithError(
-			releaseHotspotWithError(ctx.getString(
+					ctx.getString(R.string.hotspot_error_framework_busy));
-					R.string.hotspot_error_start_callback_failed_unknown,
-					reason));
 		}
 	}
 
+	@UiThread
 	void stopWifiP2pHotspot() {
 		if (channel == null) return;
 		wifiP2pManager.removeGroup(channel, new ActionListener() {
 			@Override
 			public void onSuccess() {
-				releaseHotspot();
+				closeChannelAndReleaseLocks();
 			}
 
 			@Override
 			public void onFailure(int reason) {
 				// not propagating back error
-				releaseHotspot();
+				if (LOG.isLoggable(WARNING)) {
+					LOG.warning("Error removing Wifi P2P group: " + reason);
+				}
+				closeChannelAndReleaseLocks();
 			}
 		});
 	}
 
-	private void acquireLock() {
+	@SuppressLint("WakelockTimeout")
+	private void acquireLocks() {
+		// FLAG_KEEP_SCREEN_ON is not respected on some Huawei devices.
+		wakeLock = powerManager.newWakeLock(FULL_WAKE_LOCK, lockTag);
+		wakeLock.acquire();
 		// WIFI_MODE_FULL has no effect on API >= 29
 		int lockType =
 				SDK_INT >= 29 ? WIFI_MODE_FULL_HIGH_PERF : WIFI_MODE_FULL;
@@ -212,22 +291,21 @@ class HotspotManager implements ActionListener {
 		wifiLock.acquire();
 	}
 
-	private void releaseHotspot() {
+	@UiThread
-		listener.onHotspotStopped();
-		closeChannelAndReleaseLock();
-	}
-
 	private void releaseHotspotWithError(String error) {
 		listener.onHotspotError(error);
-		closeChannelAndReleaseLock();
+		closeChannelAndReleaseLocks();
 	}
 
-	private void closeChannelAndReleaseLock() {
+	@UiThread
-		if (SDK_INT >= 27) channel.close();
+	private void closeChannelAndReleaseLocks() {
+		if (SDK_INT >= 27 && channel != null) channel.close();
 		channel = null;
-		wifiLock.release();
+		if (wakeLock.isHeld()) wakeLock.release();
+		if (wifiLock.isHeld()) wifiLock.release();
 	}
 
+	@UiThread
 	private void requestGroupInfo(int attempt) {
 		if (LOG.isLoggable(INFO)) {
 			LOG.info("requestGroupInfo attempt: " + attempt);
@@ -257,7 +335,8 @@ class HotspotManager implements ActionListener {
 		ioExecutor.execute(() -> {
 			String content = createWifiLoginString(group.getNetworkName(),
 					group.getPassphrase());
-			Bitmap qrCode = QrCodeUtils.createQrCode(dm, content);
+			Bitmap qrCode = QrCodeUtils.createQrCode(
+					(int) (dm.heightPixels * HOTSPOT_QRCODE_FACTOR), content);
 			NetworkConfig config = new NetworkConfig(group.getNetworkName(),
 					group.getPassphrase(), qrCode);
 			listener.onHotspotStarted(config);
@@ -270,27 +349,22 @@ class HotspotManager implements ActionListener {
 			LOG.info("group is null");
 			return false;
 		} else if (!group.getNetworkName().startsWith("DIRECT-")) {
-			if (LOG.isLoggable(INFO)) {
+			LOG.info("received networkName without prefix 'DIRECT-'");
-				LOG.info("received networkName without prefix 'DIRECT-': " +
-						group.getNetworkName());
-			}
 			return false;
 		} else if (SDK_INT >= 29) {
 			// if we get here, the savedNetworkConfig must have a value
-			String networkName = savedNetworkConfig.ssid;
+			String networkName = requireNonNull(savedNetworkConfig).ssid;
 			if (!networkName.equals(group.getNetworkName())) {
-				if (LOG.isLoggable(INFO)) {
+				LOG.info("expected networkName does not match received one");
-					LOG.info("expected networkName: " + networkName);
-					LOG.info("received networkName: " + group.getNetworkName());
-				}
 				return false;
 			}
 		}
 		return true;
 	}
 
+	@UiThread
 	private void retryRequestingGroupInfo(int attempt) {
-		LOG.info("retrying");
+		LOG.info("retrying to request group info");
 		// On some devices we need to wait for the group info to become available
 		if (attempt < MAX_GROUP_INFO_ATTEMPTS) {
 			handler.postDelayed(() -> requestGroupInfo(attempt + 1),
@@ -303,19 +377,13 @@ class HotspotManager implements ActionListener {
 
 	@UiThread
 	private void requestGroupInfoForConnection() {
-		if (LOG.isLoggable(INFO)) {
+		LOG.info("requestGroupInfo for connection");
-			LOG.info("requestGroupInfo for connection");
-		}
 		GroupInfoListener groupListener = group -> {
-			if (group == null || group.getClientList().isEmpty()) {
+			if (group != null) {
-				handler.postDelayed(this::requestGroupInfoForConnection,
+				listener.onPeersUpdated(group.getClientList().size());
-						RETRY_DELAY_MILLIS);
-			} else {
-				if (LOG.isLoggable(INFO)) {
-					LOG.info("client list " + group.getClientList());
-				}
-				listener.onDeviceConnected();
 			}
+			handler.postDelayed(this::requestGroupInfoForConnection,
+					RETRY_DELAY_MILLIS);
 		};
 		try {
 			if (channel == null) return;
@@ -371,26 +439,15 @@ class HotspotManager implements ActionListener {
 		return "WIFI:S:" + ssid + ";T:WPA;P:" + password + ";;";
 	}
 
-	private static final String digits = "123456789"; // avoid 0
+	// exclude chars that are easy to confuse: 0 (O), 5 (S), 1 l (I)
-	private static final String letters = "abcdefghijkmnopqrstuvwxyz"; // no l
+	private static final String chars = "2346789abcdefghijkmnopqrstuvwxyz";
-	private static final String LETTERS = "ABCDEFGHJKLMNPQRSTUVWXYZ"; // no I, O
 
 	private String getRandomString(int length) {
 		char[] c = new char[length];
 		for (int i = 0; i < length; i++) {
-			if (random.nextBoolean()) {
+			c[i] = chars.charAt(random.nextInt(chars.length()));
-				c[i] = random(digits);
-			} else if (random.nextBoolean()) {
-				c[i] = random(letters);
-			} else {
-				c[i] = random(LETTERS);
-			}
 		}
 		return new String(c);
 	}
 
-	private char random(String universe) {
-		return universe.charAt(random.nextInt(universe.length()));
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/hotspot/HotspotState.java

@@ -57,16 +57,19 @@ abstract class HotspotState {
 			return websiteConfig;
 		}
 
+		@UiThread
+		boolean wasNotYetConsumed() {
+			return !consumed;
+		}
+
 		/**
 		 * Mark this state as consumed, i.e. the UI has already done something
 		 * as a result of the state changing to this. This can be used in order
 		 * to not repeat actions such as showing fragments on rotation changes.
 		 */
 		@UiThread
-		boolean consume() {
+		void consume() {
-			boolean old = consumed;
 			consumed = true;
-			return old;
 		}
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/hotspot/HotspotViewModel.java

@@ -63,8 +63,8 @@ class HotspotViewModel extends DbViewModel
 
 	private final MutableLiveData<HotspotState> state =
 			new MutableLiveData<>();
-	private final MutableLiveEvent<Boolean> peerConnected =
+	private final MutableLiveData<Integer> peersConnected =
-			new MutableLiveEvent<>();
+			new MutableLiveData<>();
 	private final MutableLiveEvent<Uri> savedApkToUri =
 			new MutableLiveEvent<>();
 
@@ -137,14 +137,8 @@ class HotspotViewModel extends DbViewModel
 
 	@UiThread
 	@Override
-	public void onDeviceConnected() {
+	public void onPeersUpdated(int peers) {
-		peerConnected.setEvent(true);
+		peersConnected.setValue(peers);
-	}
-
-	@Override
-	public void onHotspotStopped() {
-		LOG.info("stopping webserver");
-		ioExecutor.execute(webServerManager::stopWebServer);
 	}
 
 	@Override
@@ -170,7 +164,7 @@ class HotspotViewModel extends DbViewModel
 	public void onWebServerError() {
 		state.postValue(new HotspotError(getApplication()
 				.getString(R.string.hotspot_error_web_server_start)));
-		hotspotManager.stopWifiP2pHotspot();
+		stopHotspot();
 	}
 
 	void exportApk(Uri uri) {
@@ -219,8 +213,8 @@ class HotspotViewModel extends DbViewModel
 		return state;
 	}
 
-	LiveEvent<Boolean> getPeerConnectedEvent() {
+	LiveData<Integer> getPeersConnectedEvent() {
-		return peerConnected;
+		return peersConnected;
 	}
 
 	LiveEvent<Uri> getSavedApkToUri() {

briar-android/src/main/java/org/briarproject/briar/android/hotspot/QrHotspotFragment.java

@@ -1,12 +1,14 @@
 package org.briarproject.briar.android.hotspot;
 
 import android.content.Context;
+import android.graphics.Bitmap;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ImageView;
 import android.widget.TextView;
+import android.widget.Toast;
 
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
@@ -16,7 +18,6 @@ import org.briarproject.briar.android.hotspot.HotspotState.HotspotStarted;
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
-import androidx.core.util.Consumer;
 import androidx.fragment.app.Fragment;
 import androidx.lifecycle.ViewModelProvider;
 
@@ -60,19 +61,23 @@ public class QrHotspotFragment extends Fragment {
 		TextView qrIntroView = v.findViewById(R.id.qrIntroView);
 		ImageView qrCodeView = v.findViewById(R.id.qrCodeView);
 
-		Consumer<HotspotStarted> consumer;
+		boolean forWifi = requireArguments().getBoolean(ARG_FOR_WIFI_CONNECT);
-		if (requireArguments().getBoolean(ARG_FOR_WIFI_CONNECT)) {
+
-			qrIntroView.setText(R.string.hotspot_qr_wifi);
+		qrIntroView.setText(forWifi ? R.string.hotspot_qr_wifi :
-			consumer = state ->
+				R.string.hotspot_qr_site);
-					qrCodeView.setImageBitmap(state.getNetworkConfig().qrCode);
+
-		} else {
-			qrIntroView.setText(R.string.hotspot_qr_site);
-			consumer = state ->
-					qrCodeView.setImageBitmap(state.getWebsiteConfig().qrCode);
-		}
 		viewModel.getState().observe(getViewLifecycleOwner(), state -> {
 			if (state instanceof HotspotStarted) {
-				consumer.accept((HotspotStarted) state);
+				HotspotStarted s = (HotspotStarted) state;
+				Bitmap qrCode = forWifi ? s.getNetworkConfig().qrCode :
+						s.getWebsiteConfig().qrCode;
+				if (qrCode == null) {
+					Toast.makeText(requireContext(), R.string.error,
+							Toast.LENGTH_SHORT).show();
+					qrCodeView.setImageResource(R.drawable.ic_image_broken);
+				} else {
+					qrCodeView.setImageBitmap(qrCode);
+				}
 			}
 		});
 		return v;

briar-android/src/main/java/org/briarproject/briar/android/hotspot/WebServerManager.java

@@ -14,22 +14,20 @@ import java.io.IOException;
 import java.net.InetAddress;
 import java.net.InterfaceAddress;
 import java.net.NetworkInterface;
-import java.net.SocketException;
-import java.util.Enumeration;
-import java.util.List;
 import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
+import androidx.annotation.UiThread;
 
-import static java.util.Collections.emptyList;
-import static java.util.Collections.list;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.NetworkUtils.getNetworkInterfaces;
 import static org.briarproject.briar.android.hotspot.WebServer.PORT;
+import static org.briarproject.briar.android.util.QrCodeUtils.HOTSPOT_QRCODE_FACTOR;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -49,7 +47,7 @@ class WebServerManager {
 	private final WebServer webServer;
 	private final DisplayMetrics dm;
 
-	private WebServerListener listener;
+	private volatile WebServerListener listener;
 
 	@Inject
 	WebServerManager(Application ctx) {
@@ -57,6 +55,7 @@ class WebServerManager {
 		dm = ctx.getResources().getDisplayMetrics();
 	}
 
+	@UiThread
 	void setListener(WebServerListener listener) {
 		this.listener = listener;
 	}
@@ -85,7 +84,8 @@ class WebServerManager {
 			}
 			url = "http://" + address.getHostAddress() + ":" + PORT;
 		}
-		Bitmap qrCode = QrCodeUtils.createQrCode(dm, url);
+		Bitmap qrCode = QrCodeUtils.createQrCode(
+				(int) (dm.heightPixels * HOTSPOT_QRCODE_FACTOR), url);
 		listener.onWebServerStarted(new WebsiteConfig(url, qrCode));
 	}
 
@@ -110,16 +110,4 @@ class WebServerManager {
 		}
 		return null;
 	}
-
-	private static List<NetworkInterface> getNetworkInterfaces() {
-		try {
-			Enumeration<NetworkInterface> ifaces =
-					NetworkInterface.getNetworkInterfaces();
-			return ifaces == null ? emptyList() : list(ifaces);
-		} catch (SocketException e) {
-			logException(LOG, WARNING, e);
-			return emptyList();
-		}
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/NavDrawerActivity.java

@@ -29,6 +29,7 @@ import org.briarproject.bramble.api.plugin.TorConstants;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.BriarApplication;
+import org.briarproject.briar.android.StartupFailureActivity;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
 import org.briarproject.briar.android.blog.FeedFragment;
@@ -73,6 +74,7 @@ import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
 import static org.briarproject.bramble.api.plugin.Plugin.State.ENABLING;
 import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
 import static org.briarproject.briar.android.BriarService.EXTRA_STARTUP_FAILED;
+import static org.briarproject.briar.android.BriarService.EXTRA_START_RESULT;
 import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_PASSWORD;
 import static org.briarproject.briar.android.navdrawer.IntentRouter.handleExternalIntent;
@@ -250,6 +252,11 @@ public class NavDrawerActivity extends BriarActivity implements
 
 	private void exitIfStartupFailed(Intent intent) {
 		if (intent.getBooleanExtra(EXTRA_STARTUP_FAILED, false)) {
+			// Launch StartupFailureActivity in its own process, then exit
+			Intent i = new Intent(this, StartupFailureActivity.class);
+			i.putExtra(EXTRA_START_RESULT,
+					intent.getSerializableExtra(EXTRA_START_RESULT));
+			startActivity(i);
 			finish();
 			LOG.info("Exiting");
 			System.exit(0);

briar-android/src/main/java/org/briarproject/briar/android/removabledrive/ChooserFragment.java

@@ -11,6 +11,7 @@ import android.widget.ScrollView;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.widget.OnboardingFullDialogFragment;
 
 import javax.inject.Inject;
 
@@ -51,6 +52,10 @@ public class ChooserFragment extends Fragment {
 				container, false);
 
 		scrollView = (ScrollView) v;
+
+		Button buttonLearnMore = v.findViewById(R.id.buttonLearnMore);
+		buttonLearnMore.setOnClickListener(e -> showLearnMoreDialog());
+
 		Button sendButton = v.findViewById(R.id.sendButton);
 		sendButton.setOnClickListener(i -> viewModel.startSendData());
 
@@ -75,4 +80,10 @@ public class ChooserFragment extends Fragment {
 		}
 	}
 
+	private void showLearnMoreDialog() {
+		OnboardingFullDialogFragment.newInstance(
+				R.string.removable_drive_menu_title,
+				R.string.removable_drive_explanation
+		).show(getChildFragmentManager(), OnboardingFullDialogFragment.TAG);
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/removabledrive/ReceiveFragment.java

@@ -47,6 +47,8 @@ public class ReceiveFragment extends Fragment {
 	private Button button;
 	private ProgressBar progressBar;
 
+	private boolean checkForStateLoss = false;
+
 	@Override
 	public void onAttach(Context context) {
 		super.onAttach(context);
@@ -73,6 +75,10 @@ public class ReceiveFragment extends Fragment {
 				.observeEvent(getViewLifecycleOwner(), this::onOldTaskResumed);
 		viewModel.getState()
 				.observe(getViewLifecycleOwner(), this::onStateChanged);
+
+		// need to check for lost ViewModel state when creating with prior state
+		if (savedInstanceState != null) checkForStateLoss = true;
+
 		return v;
 	}
 
@@ -84,6 +90,23 @@ public class ReceiveFragment extends Fragment {
 		scrollView.post(() -> scrollView.fullScroll(FOCUS_DOWN));
 	}
 
+	@Override
+	public void onResume() {
+		super.onResume();
+		// This code gets called *after* launcher had a chance
+		// to return the activity result.
+		if (checkForStateLoss && viewModel.hasNoState()) {
+			// We were recreated, but have lost the ViewModel state,
+			// because our activity was destroyed.
+			//
+			// Remove the current fragment from the stack
+			// to prevent duplicates on the back stack.
+			getParentFragmentManager().popBackStack();
+			// Start again (picks up existing task or allows to start a new one)
+			viewModel.startReceiveData();
+		}
+	}
+
 	private void onOldTaskResumed(boolean resumed) {
 		if (resumed) {
 			Toast.makeText(requireContext(),
@@ -104,6 +127,8 @@ public class ReceiveFragment extends Fragment {
 
 	private void onDocumentChosen(@Nullable Uri uri) {
 		if (uri == null) return;
+		// we just got our document, so don't treat this as a state loss
+		checkForStateLoss = false;
 		viewModel.importData(uri);
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/removabledrive/RemovableDriveViewModel.java

@@ -75,6 +75,12 @@ class RemovableDriveViewModel extends DbViewModel {
 		}
 	}
 
+	@UiThread
+	boolean hasNoState() {
+		return action.getLastValue() == null && state.getValue() == null &&
+				task == null;
+	}
+
 	/**
 	 * Set this as soon as it becomes available.
 	 */

briar-android/src/main/java/org/briarproject/briar/android/removabledrive/SendFragment.java

@@ -51,6 +51,8 @@ public class SendFragment extends Fragment {
 	private Button button;
 	private ProgressBar progressBar;
 
+	private boolean checkForStateLoss = false;
+
 	@Override
 	public void onAttach(Context context) {
 		super.onAttach(context);
@@ -80,6 +82,9 @@ public class SendFragment extends Fragment {
 		viewModel.getState()
 				.observe(getViewLifecycleOwner(), this::onStateChanged);
 
+		// need to check for lost ViewModel state when creating with prior state
+		if (savedInstanceState != null) checkForStateLoss = true;
+
 		return v;
 	}
 
@@ -91,6 +96,23 @@ public class SendFragment extends Fragment {
 		scrollView.post(() -> scrollView.fullScroll(FOCUS_DOWN));
 	}
 
+	@Override
+	public void onResume() {
+		super.onResume();
+		// This code gets called *after* launcher had a chance
+		// to return the activity result.
+		if (checkForStateLoss && viewModel.hasNoState()) {
+			// We were recreated, but have lost the ViewModel state,
+			// because our activity was destroyed.
+			//
+			// Remove the current fragment from the stack
+			// to prevent duplicates on the back stack.
+			getParentFragmentManager().popBackStack();
+			// Start again (picks up existing task or allows to start a new one)
+			viewModel.startSendData();
+		}
+	}
+
 	private void onOldTaskResumed(boolean resumed) {
 		if (resumed) {
 			Toast.makeText(requireContext(),
@@ -127,6 +149,8 @@ public class SendFragment extends Fragment {
 
 	private void onDocumentCreated(@Nullable Uri uri) {
 		if (uri == null) return;
+		// we just got our document, so don't treat this as a state loss
+		checkForStateLoss = false;
 		viewModel.exportData(uri);
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/reporting/BriarExceptionHandler.java

@@ -2,6 +2,7 @@ package org.briarproject.briar.android.reporting;
 
 import android.app.Application;
 import android.os.Process;
+import android.util.Log;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.android.logging.LogEncrypter;
@@ -10,6 +11,7 @@ import java.lang.Thread.UncaughtExceptionHandler;
 
 import javax.inject.Inject;
 
+import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 import static org.briarproject.briar.android.util.UiUtils.startDevReportActivity;
 
 @NotNullByDefault
@@ -28,6 +30,8 @@ class BriarExceptionHandler implements UncaughtExceptionHandler {
 
 	@Override
 	public void uncaughtException(Thread t, Throwable e) {
+		if (IS_DEBUG_BUILD) Log.w("Uncaught exception", e);
+
 		// encrypt logs to disk before handing over to new process
 		// the intent has limited space, so we can't reliably store them there.
 		byte[] logKey = logEncrypter.encryptLogs();

briar-android/src/main/java/org/briarproject/briar/android/util/QrCodeUtils.java

@@ -26,13 +26,19 @@ public class QrCodeUtils {
 
 	private static final Logger LOG = getLogger(QrCodeUtils.class.getName());
 
+	public static final double HOTSPOT_QRCODE_FACTOR = 0.35;
+
 	@Nullable
 	public static Bitmap createQrCode(DisplayMetrics dm, String input) {
-		int smallestDimen = Math.min(dm.widthPixels, dm.heightPixels);
+		return createQrCode(Math.min(dm.widthPixels, dm.heightPixels), input);
+	}
+
+	@Nullable
+	public static Bitmap createQrCode(int edgeLen, String input) {
 		try {
 			// Generate QR code
 			BitMatrix encoded = new QRCodeWriter().encode(input, QR_CODE,
-					smallestDimen, smallestDimen);
+					edgeLen, edgeLen);
 			return renderQrCode(encoded);
 		} catch (WriterException e) {
 			logException(LOG, WARNING, e);

briar-android/src/main/java/org/briarproject/briar/android/util/UiUtils.java

@@ -62,7 +62,6 @@ import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentActivity;
 import androidx.fragment.app.FragmentManager;
 import androidx.fragment.app.FragmentTransaction;
-import androidx.fragment.app.FragmentManager;
 import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.Observer;
@@ -341,11 +340,6 @@ public class UiUtils {
 		return i;
 	}
 
-	public static void putShowAdvancedExtra(Intent i) {
-		i.putExtra(SDK_INT <= 28 ? "android.content.extra.SHOW_ADVANCED" :
-				"android.provider.extra.SHOW_ADVANCED", true);
-	}
-
 	/**
 	 * @return true if location is enabled,
 	 * or it isn't required due to this being a SDK < 28 device.
@@ -567,4 +561,5 @@ public class UiUtils {
 		activity.getWindow().setSoftInputMode(SOFT_INPUT_ADJUST_RESIZE |
 				SOFT_INPUT_STATE_HIDDEN);
 	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/view/AuthorView.java

@@ -3,6 +3,7 @@ package org.briarproject.briar.android.view;
 import android.content.Context;
 import android.content.res.TypedArray;
 import android.graphics.Typeface;
+import android.graphics.drawable.Drawable;
 import android.util.AttributeSet;
 import android.view.LayoutInflater;
 import android.widget.ImageView;
@@ -29,6 +30,7 @@ import im.delight.android.identicons.IdenticonDrawable;
 import static android.content.Context.LAYOUT_INFLATER_SERVICE;
 import static android.graphics.Typeface.BOLD;
 import static android.util.TypedValue.COMPLEX_UNIT_PX;
+import static androidx.appcompat.content.res.AppCompatResources.getDrawable;
 import static org.briarproject.briar.android.util.UiUtils.getContactDisplayName;
 import static org.briarproject.briar.android.util.UiUtils.resolveAttribute;
 import static org.briarproject.briar.api.identity.AuthorInfo.Status.NONE;
@@ -177,14 +179,14 @@ public class AuthorView extends ConstraintLayout {
 			case RSS_FEED:
 				avatarIcon.setVisibility(INVISIBLE);
 				date.setVisibility(VISIBLE);
-				avatar.setImageResource(R.drawable.ic_rss_feed);
+				setRssVectorAvatar();
 				setAvatarSize(R.dimen.blogs_avatar_normal_size);
 				setTextSize(authorName, R.dimen.text_size_small);
 				break;
 			case RSS_FEED_REBLOGGED:
 				avatarIcon.setVisibility(INVISIBLE);
 				date.setVisibility(VISIBLE);
-				avatar.setImageResource(R.drawable.ic_rss_feed);
+				setRssVectorAvatar();
 				setAvatarSize(R.dimen.blogs_avatar_comment_size);
 				setTextSize(authorName, R.dimen.text_size_tiny);
 				break;
@@ -204,4 +206,16 @@ public class AuthorView extends ConstraintLayout {
 		v.setTextSize(COMPLEX_UNIT_PX, textSize);
 	}
 
+	/**
+	 * Applies special hack to use AppCompat vector drawable support
+	 * when setting the RSS vector drawable to the avatar view.
+	 * {@link ImageView#setImageResource(int)} is not working as
+	 * {@link CircleImageView} is not using
+	 * {@link androidx.appcompat.widget.AppCompatImageView}.
+	 */
+	private void setRssVectorAvatar() {
+		Drawable d = getDrawable(getContext(), R.drawable.ic_rss_feed);
+		avatar.setImageDrawable(d);
+	}
+
 }

briar-android/src/main/java/org/briarproject/briar/api/android/AndroidNotificationManager.java

@@ -42,10 +42,13 @@ public interface AndroidNotificationManager {
 	// that will sort below the main channels such as contacts
 	String ONGOING_CHANNEL_OLD_ID = "zForegroundService";
 	String ONGOING_CHANNEL_ID = "zForegroundService2";
-	String FAILURE_CHANNEL_ID = "zStartupFailure";
 	String REMINDER_CHANNEL_ID = "zSignInReminder";
 	String HOTSPOT_CHANNEL_ID = "zHotspot";
 
+	// This channel is no longer used - keep the ID so we can remove the
+	// channel from existing installations
+	String FAILURE_CHANNEL_ID = "zStartupFailure";
+
 	// Actions for pending intents
 	String ACTION_DISMISS_REMINDER = "dismissReminder";
 	String ACTION_STOP_HOTSPOT = "stopHotspot";

briar-android/src/main/res/drawable/ic_bluetooth.xml

@@ -0,0 +1,21 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+	android:width="100dp"
+	android:height="35dp"
+	android:viewportWidth="500"
+	android:viewportHeight="175">
+	<path
+		android:fillColor="?attr/colorControlNormal"
+		android:pathData="m459.809,167.16 l-4.327,-4.334 -7.07,-2.427c-3.888,-1.335 -8.723,-2.996 -10.744,-3.691l-3.674,-1.263 3.524,-0.173c8.242,-0.404 12.988,-4.007 14.336,-10.884 0.796,-4.061 1.129,-17.298 0.83,-33.041 -0.153,-8.084 -0.166,-15.416 -0.028,-16.295 0.138,-0.878 0.535,-2.42 0.883,-3.426 1.222,-3.532 0.34,-11.908 -1.858,-17.631 -0.348,-0.908 -1.934,-4.215 -3.524,-7.35 -4.158,-8.2 -4.505,-8.942 -4.893,-10.484 -0.459,-1.821 -0.212,-5.435 0.463,-6.766 0.666,-1.315 2.157,-2.916 3.246,-3.487 1.299,-0.68 2.616,0.122 4.686,2.855 3.422,4.516 14.001,19.441 15.732,22.193 3.746,5.956 5.956,11.165 7.972,18.788 0.655,2.475 1.885,6.997 2.735,10.05 0.849,3.053 2.714,10.158 4.144,15.79l2.6,10.24 4.65,5.193c2.557,2.856 5.798,6.464 7.2,8.017 1.403,1.553 2.55,2.975 2.55,3.161 0,0.335 -34.5,29.299 -34.899,29.299 -0.115,0 -2.156,-1.95 -4.535,-4.334zM365.944,150.772c-1.258,-0.628 -2.206,-1.379 -2.914,-2.307 -2.089,-2.736 -1.95,2.369 -1.864,-68.482l0.078,-64.039 0.661,-1.235c1.015,-1.898 1.992,-2.911 3.74,-3.879l1.6,-0.886 37.784,-0.08c42.456,-0.089 39.402,-0.248 42.116,2.192 0.875,0.787 1.757,1.959 2.184,2.904 0.713,1.577 0.716,1.638 0.806,14.204l0.09,12.62 -1.798,-0.13c-1.426,-0.103 -2.081,0.007 -3.166,0.532 -2.013,0.974 -3.94,2.899 -5.115,5.108l-1.037,1.95 -0.007,-12.825 -0.007,-12.825h-33.6,-33.6v51.3,51.3h33.599,33.599l0.076,-34.425c0.073,-32.96 0.098,-34.361 0.591,-32.925 0.283,0.825 1.806,3.997 3.383,7.05 5.493,10.626 5.405,9.86 5.396,47.203 -0.007,27.621 -0.124,29.951 -1.662,33.109 -1.071,2.199 -2.711,3.71 -5.058,4.66l-1.674,0.677 -36.168,0.08 -36.168,0.08 -1.864,-0.931zM408.344,145.734c2.871,-1.309 4.458,-3.678 4.43,-6.617 -0.039,-4.116 -3.109,-7.223 -7.136,-7.223 -2.12,0 -3.567,0.609 -5.164,2.172 -2.245,2.198 -2.754,5.439 -1.301,8.287 0.713,1.398 2.521,3.009 3.962,3.53 1.497,0.542 3.84,0.475 5.209,-0.149z" />
+	<path
+		android:fillColor="?attr/colorControlNormal"
+		android:pathData="m39.434,167.16 l4.327,-4.334 7.07,-2.427c3.888,-1.335 8.723,-2.996 10.744,-3.691l3.674,-1.263 -3.524,-0.173c-8.242,-0.404 -12.988,-4.007 -14.336,-10.884 -0.796,-4.061 -1.129,-17.298 -0.83,-33.041 0.153,-8.084 0.166,-15.416 0.028,-16.295 -0.138,-0.878 -0.535,-2.42 -0.883,-3.426 -1.222,-3.532 -0.34,-11.908 1.858,-17.631 0.348,-0.908 1.934,-4.215 3.524,-7.35 4.158,-8.2 4.505,-8.942 4.893,-10.484 0.459,-1.821 0.212,-5.435 -0.463,-6.766 -0.666,-1.315 -2.157,-2.916 -3.246,-3.487 -1.299,-0.68 -2.616,0.122 -4.686,2.855 -3.422,4.516 -14.001,19.441 -15.732,22.193 -3.746,5.956 -5.956,11.165 -7.972,18.788 -0.655,2.475 -1.885,6.997 -2.735,10.05 -0.849,3.053 -2.714,10.158 -4.144,15.79L14.4,125.824 9.75,131.017c-2.557,2.856 -5.798,6.464 -7.2,8.017 -1.403,1.553 -2.55,2.975 -2.55,3.161 0,0.335 34.5,29.299 34.899,29.299 0.115,0 2.156,-1.95 4.535,-4.334zM133.299,150.772c1.258,-0.628 2.206,-1.379 2.914,-2.307 2.089,-2.736 1.95,2.369 1.864,-68.482l-0.078,-64.039 -0.661,-1.235c-1.015,-1.898 -1.992,-2.911 -3.74,-3.879L132,9.944 94.216,9.865c-42.456,-0.089 -39.402,-0.248 -42.116,2.192 -0.875,0.787 -1.757,1.959 -2.184,2.904 -0.713,1.577 -0.716,1.638 -0.806,14.204l-0.09,12.62 1.798,-0.13c1.426,-0.103 2.081,0.007 3.166,0.532 2.013,0.974 3.94,2.899 5.115,5.108l1.037,1.95 0.007,-12.825 0.007,-12.825h33.6,33.6v51.3,51.3L93.752,126.194 60.153,126.194l-0.076,-34.425c-0.073,-32.96 -0.098,-34.361 -0.591,-32.925 -0.283,0.825 -1.806,3.997 -3.383,7.05 -5.493,10.626 -5.405,9.86 -5.396,47.203 0.007,27.621 0.124,29.951 1.662,33.109 1.071,2.199 2.711,3.71 5.058,4.66l1.674,0.677 36.168,0.08 36.168,0.08 1.864,-0.931zM90.9,145.734c-2.871,-1.309 -4.458,-3.678 -4.43,-6.617 0.039,-4.116 3.109,-7.223 7.136,-7.223 2.12,0 3.567,0.609 5.164,2.172 2.245,2.198 2.754,5.439 1.301,8.287 -0.713,1.398 -2.521,3.009 -3.962,3.53 -1.497,0.542 -3.84,0.475 -5.209,-0.149z" />
+	<path
+		android:fillColor="#0a3d91"
+		android:pathData="m247.254,71.979h4.736c13.165,0 23.763,10.599 23.763,23.763v32.175c0,13.165 -10.599,23.763 -23.763,23.763h-4.736c-13.165,0 -23.763,-10.599 -23.763,-23.763V95.743c0,-13.165 10.599,-23.763 23.763,-23.763z" />
+	<path
+		android:fillColor="#0a3d91"
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+	<path
+		android:fillColor="#ffffff"
+		android:pathData="m252.501,112.09 l11.656,-11.452 -17.126,-19.791 0.019,25.792 -9.142,-9.245 -3.125,3.091 11.521,11.581 -11.498,11.308c3.031,3.056 0,0 3.031,3.056l9.189,-8.973c0.044,4.735 0.004,27.165 0.004,27.165l17.102,-20.773zM251.424,92.519 L258.222,100.383 251.424,107.016zM251.4,132.547 L251.424,117.151 258.317,124.139z" />
+</vector>

briar-android/src/main/res/layout/fragment_bluetooth_intro.xml

@@ -0,0 +1,51 @@
+<?xml version="1.0" encoding="utf-8"?>
+<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:app="http://schemas.android.com/apk/res-auto"
+	xmlns:tools="http://schemas.android.com/tools"
+	android:layout_width="match_parent"
+	android:layout_height="match_parent"
+	android:fillViewport="true"
+	tools:context=".android.contact.connect.BluetoothIntroFragment">
+
+	<androidx.constraintlayout.widget.ConstraintLayout
+		android:layout_width="match_parent"
+		android:layout_height="wrap_content">
+
+		<androidx.appcompat.widget.AppCompatImageView
+			android:id="@+id/introImageView"
+			android:layout_width="0dp"
+			android:layout_height="0dp"
+			android:layout_margin="16dp"
+			app:layout_constraintBottom_toTopOf="@+id/introTextView"
+			app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintHeight_percent="0.2"
+			app:layout_constraintStart_toStartOf="parent"
+			app:layout_constraintTop_toTopOf="parent"
+			app:srcCompat="@drawable/ic_bluetooth" />
+
+		<TextView
+			android:id="@+id/introTextView"
+			android:layout_width="0dp"
+			android:layout_height="wrap_content"
+			android:layout_margin="16dp"
+			android:text="@string/connect_via_bluetooth_intro"
+			app:layout_constraintBottom_toTopOf="@+id/startButton"
+			app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintHorizontal_bias="0.5"
+			app:layout_constraintStart_toStartOf="parent"
+			app:layout_constraintTop_toBottomOf="@+id/introImageView" />
+
+		<Button
+			android:id="@+id/startButton"
+			style="@style/BriarButton"
+			android:layout_width="0dp"
+			android:layout_height="wrap_content"
+			android:layout_margin="16dp"
+			android:text="@string/start"
+			app:layout_constraintBottom_toBottomOf="parent"
+			app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintStart_toStartOf="parent" />
+
+	</androidx.constraintlayout.widget.ConstraintLayout>
+
+</ScrollView>

briar-android/src/main/res/layout/fragment_bluetooth_progress.xml

@@ -0,0 +1,43 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:app="http://schemas.android.com/apk/res-auto"
+	android:layout_width="match_parent"
+	android:layout_height="match_parent">
+
+	<androidx.appcompat.widget.AppCompatImageView
+		android:id="@+id/introImageView"
+		android:layout_width="0dp"
+		android:layout_height="0dp"
+		android:layout_margin="16dp"
+		app:layout_constraintBottom_toTopOf="@+id/progressBar"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintHeight_percent="0.2"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="parent"
+		app:layout_constraintVertical_chainStyle="packed"
+		app:srcCompat="@drawable/ic_bluetooth" />
+
+	<ProgressBar
+		android:id="@+id/progressBar"
+		style="?android:attr/progressBarStyleHorizontal"
+		android:layout_width="0dp"
+		android:layout_height="wrap_content"
+		android:indeterminate="true"
+		app:layout_constraintBottom_toTopOf="@+id/textView"
+		app:layout_constraintEnd_toEndOf="@+id/introImageView"
+		app:layout_constraintStart_toStartOf="@+id/introImageView"
+		app:layout_constraintTop_toBottomOf="@+id/introImageView" />
+
+	<TextView
+		android:id="@+id/textView"
+		android:layout_width="0dp"
+		android:layout_height="wrap_content"
+		android:layout_margin="16dp"
+		android:gravity="center"
+		android:text="@string/connect_via_bluetooth_start"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toBottomOf="@+id/progressBar" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

briar-android/src/main/res/layout/fragment_crash.xml

@@ -5,31 +5,30 @@
 	android:layout_width="match_parent"
 	android:layout_height="match_parent">
 
-	<ScrollView
+	<androidx.core.widget.NestedScrollView
 		android:id="@+id/scrollView"
-		android:layout_width="match_parent"
+		android:layout_width="0dp"
 		android:layout_height="0dp"
 		android:fillViewport="true"
 		app:layout_constraintBottom_toTopOf="@+id/acceptButton"
+		app:layout_constraintEnd_toEndOf="parent"
 		app:layout_constraintStart_toStartOf="parent"
 		app:layout_constraintTop_toTopOf="parent">
 
 		<androidx.constraintlayout.widget.ConstraintLayout
 			android:layout_width="match_parent"
 			android:layout_height="wrap_content"
-			android:padding="@dimen/margin_large">
+			android:layout_margin="@dimen/margin_xlarge">
 
 			<androidx.appcompat.widget.AppCompatImageView
 				android:id="@+id/errorIcon"
-				android:layout_width="0dp"
+				android:layout_width="@dimen/hero_square"
-				android:layout_height="0dp"
+				android:layout_height="@dimen/hero_square"
-				android:padding="8dp"
 				app:layout_constraintBottom_toTopOf="@+id/crashed"
-				app:layout_constraintDimensionRatio="1:1"
 				app:layout_constraintEnd_toEndOf="parent"
-				app:layout_constraintHeight_max="128dp"
 				app:layout_constraintStart_toStartOf="parent"
 				app:layout_constraintTop_toTopOf="parent"
+				app:layout_constraintVertical_bias="0.25"
 				app:layout_constraintVertical_chainStyle="packed"
 				app:srcCompat="@drawable/ic_crash"
 				app:tint="?attr/colorControlNormal"
@@ -39,25 +38,23 @@
 				android:id="@+id/crashed"
 				android:layout_width="match_parent"
 				android:layout_height="wrap_content"
+				android:layout_marginTop="@dimen/margin_xlarge"
 				android:gravity="center"
 				android:text="@string/briar_crashed"
-				android:textColor="?android:attr/textColorSecondary"
+				android:textAppearance="@style/TextAppearance.MaterialComponents.Headline5"
-				android:textSize="@dimen/text_size_large"
 				app:layout_constraintBottom_toTopOf="@+id/fault"
 				app:layout_constraintEnd_toEndOf="parent"
 				app:layout_constraintStart_toStartOf="parent"
-				app:layout_constraintTop_toBottomOf="@+id/errorIcon"
+				app:layout_constraintTop_toBottomOf="@+id/errorIcon" />
-				tools:layout_editor_absoluteY="8dp" />
 
 			<TextView
 				android:id="@+id/fault"
 				android:layout_width="match_parent"
 				android:layout_height="wrap_content"
-				android:layout_marginTop="@dimen/margin_large"
+				android:layout_marginTop="@dimen/margin_xlarge"
 				android:gravity="center"
 				android:text="@string/not_your_fault"
-				android:textColor="?android:attr/textColorSecondary"
+				android:textAppearance="@style/TextAppearance.MaterialComponents.Body1"
-				android:textSize="@dimen/text_size_large"
 				app:layout_constraintBottom_toTopOf="@+id/pleaseSend"
 				app:layout_constraintEnd_toEndOf="parent"
 				app:layout_constraintStart_toStartOf="parent"
@@ -70,8 +67,7 @@
 				android:layout_marginTop="@dimen/margin_large"
 				android:gravity="center"
 				android:text="@string/please_send_report"
-				android:textColor="?android:attr/textColorSecondary"
+				android:textAppearance="@style/TextAppearance.MaterialComponents.Body1"
-				android:textSize="@dimen/text_size_large"
 				app:layout_constraintBottom_toTopOf="@+id/encrypted"
 				app:layout_constraintEnd_toEndOf="parent"
 				app:layout_constraintStart_toStartOf="parent"
@@ -84,8 +80,7 @@
 				android:layout_marginTop="@dimen/margin_large"
 				android:gravity="center"
 				android:text="@string/report_is_encrypted"
-				android:textColor="?android:attr/textColorSecondary"
+				android:textAppearance="@style/TextAppearance.MaterialComponents.Body1"
-				android:textSize="@dimen/text_size_large"
 				app:layout_constraintBottom_toBottomOf="parent"
 				app:layout_constraintEnd_toEndOf="parent"
 				app:layout_constraintStart_toStartOf="parent"
@@ -93,7 +88,7 @@
 
 		</androidx.constraintlayout.widget.ConstraintLayout>
 
-	</ScrollView>
+	</androidx.core.widget.NestedScrollView>
 
 	<Button
 		android:id="@+id/declineButton"
@@ -101,7 +96,7 @@
 		android:layout_width="0dp"
 		android:layout_height="wrap_content"
 		android:text="@string/close"
-		app:layout_constraintBottom_toBottomOf="@+id/acceptButton"
+		app:layout_constraintBottom_toBottomOf="parent"
 		app:layout_constraintEnd_toStartOf="@+id/acceptButton"
 		app:layout_constraintHorizontal_weight="1"
 		app:layout_constraintStart_toStartOf="parent"

briar-android/src/main/res/layout/fragment_error.xml

@@ -1,46 +1,55 @@
 <?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<androidx.core.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
 	xmlns:app="http://schemas.android.com/apk/res-auto"
 	xmlns:tools="http://schemas.android.com/tools"
 	android:layout_width="match_parent"
-	android:layout_height="match_parent">
+	android:layout_height="match_parent"
+	android:fillViewport="true">
 
-	<androidx.appcompat.widget.AppCompatImageView
+	<androidx.constraintlayout.widget.ConstraintLayout
-		android:id="@+id/errorIcon"
+		android:layout_width="match_parent"
-		android:layout_width="128dp"
-		android:layout_height="128dp"
-		android:layout_margin="8dp"
-		app:layout_constraintEnd_toEndOf="parent"
-		app:layout_constraintStart_toStartOf="parent"
-		app:layout_constraintTop_toTopOf="parent"
-		app:srcCompat="@drawable/alerts_and_states_error"
-		app:tint="?attr/colorControlNormal"
-		tools:ignore="ContentDescription" />
-
-	<TextView
-		android:id="@+id/errorTitle"
-		android:layout_width="wrap_content"
 		android:layout_height="wrap_content"
-		android:layout_margin="8dp"
+		android:layout_margin="@dimen/margin_xlarge">
-		android:text="@string/sorry"
-		android:textSize="@dimen/text_size_xlarge"
-		app:layout_constraintEnd_toEndOf="parent"
-		app:layout_constraintStart_toStartOf="parent"
-		app:layout_constraintTop_toBottomOf="@+id/errorIcon" />
 
-	<TextView
+		<androidx.appcompat.widget.AppCompatImageView
-		android:id="@+id/errorMessage"
+			android:id="@+id/errorIcon"
-		android:layout_width="0dp"
+			android:layout_width="@dimen/hero_square"
-		android:layout_height="wrap_content"
+			android:layout_height="@dimen/hero_square"
-		android:layout_marginStart="16dp"
+			app:layout_constraintBottom_toTopOf="@+id/errorTitle"
-		android:layout_marginLeft="16dp"
+			app:layout_constraintEnd_toEndOf="parent"
-		android:layout_marginTop="8dp"
+			app:layout_constraintStart_toStartOf="parent"
-		android:layout_marginEnd="16dp"
+			app:layout_constraintTop_toTopOf="parent"
-		android:layout_marginRight="16dp"
+			app:layout_constraintVertical_bias="0.25"
-		android:textSize="@dimen/text_size_medium"
+			app:layout_constraintVertical_chainStyle="packed"
-		app:layout_constraintEnd_toEndOf="parent"
+			app:srcCompat="@drawable/alerts_and_states_error"
-		app:layout_constraintStart_toStartOf="parent"
+			app:tint="@color/briar_red_500"
-		app:layout_constraintTop_toBottomOf="@+id/errorTitle"
+			tools:ignore="ContentDescription" />
-		tools:text="@string/startup_failed_service_error" />
 
-</androidx.constraintlayout.widget.ConstraintLayout>
+		<TextView
+			android:id="@+id/errorTitle"
+			android:layout_width="wrap_content"
+			android:layout_height="wrap_content"
+			android:layout_marginTop="@dimen/margin_xlarge"
+			android:gravity="center"
+			android:text="@string/sorry"
+			android:textAppearance="@style/TextAppearance.MaterialComponents.Headline5"
+			app:layout_constraintBottom_toTopOf="@+id/errorMessage"
+			app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintStart_toStartOf="parent"
+			app:layout_constraintTop_toBottomOf="@+id/errorIcon" />
+
+		<TextView
+			android:id="@+id/errorMessage"
+			android:layout_width="0dp"
+			android:layout_height="wrap_content"
+			android:layout_marginTop="@dimen/margin_xlarge"
+			android:textAppearance="@style/TextAppearance.MaterialComponents.Body1"
+			app:layout_constraintBottom_toBottomOf="parent"
+			app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintStart_toStartOf="parent"
+			app:layout_constraintTop_toBottomOf="@+id/errorTitle"
+			tools:text="@string/startup_failed_service_error" />
+
+	</androidx.constraintlayout.widget.ConstraintLayout>
+
+</androidx.core.widget.NestedScrollView>

briar-android/src/main/res/layout/fragment_error_contact_exchange.xml

@@ -1,108 +1,102 @@
 <?xml version="1.0" encoding="utf-8"?>
-<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
 	xmlns:app="http://schemas.android.com/apk/res-auto"
 	xmlns:tools="http://schemas.android.com/tools"
 	android:layout_width="match_parent"
-	android:layout_height="match_parent"
+	android:layout_height="match_parent">
-	android:fillViewport="true">
 
-	<androidx.constraintlayout.widget.ConstraintLayout
+	<androidx.core.widget.NestedScrollView
-		android:layout_width="match_parent"
+		android:id="@+id/scrollView"
-		android:layout_height="wrap_content">
+		android:layout_width="0dp"
+		android:layout_height="0dp"
+		android:fillViewport="true"
+		app:layout_constraintBottom_toTopOf="@+id/tryAgainButton"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="parent">
 
-		<TextView
+		<androidx.constraintlayout.widget.ConstraintLayout
-			android:id="@+id/errorTitle"
-			android:layout_width="0dp"
-			android:layout_height="wrap_content"
-			android:layout_margin="16dp"
-			android:text="@string/connection_error_title"
-			android:textColor="?android:attr/textColorPrimary"
-			android:textSize="@dimen/text_size_large"
-			app:layout_constraintEnd_toEndOf="parent"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toTopOf="parent" />
-
-		<androidx.appcompat.widget.AppCompatImageView
-			android:id="@+id/errorIcon"
 			android:layout_width="match_parent"
 			android:layout_height="wrap_content"
-			android:layout_marginLeft="16dp"
+			android:layout_margin="@dimen/margin_xlarge">
-			android:layout_marginTop="16dp"
-			android:layout_marginRight="16dp"
-			android:scaleType="fitCenter"
-			app:layout_constraintEnd_toEndOf="parent"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/errorTitle"
-			app:srcCompat="@drawable/qr_code_error"
-			app:tint="?attr/colorControlNormal"
-			tools:ignore="ContentDescription" />
 
-		<TextView
+			<androidx.appcompat.widget.AppCompatImageView
-			android:id="@+id/errorMessage"
+				android:id="@+id/errorIcon"
-			android:layout_width="0dp"
+				android:layout_width="@dimen/hero_rect_width"
-			android:layout_height="wrap_content"
+				android:layout_height="@dimen/hero_rect_height"
-			android:layout_marginStart="16dp"
+				app:layout_constraintBottom_toTopOf="@+id/errorTitle"
-			android:layout_marginLeft="16dp"
+				app:layout_constraintEnd_toEndOf="parent"
-			android:layout_marginTop="8dp"
+				app:layout_constraintStart_toStartOf="parent"
-			android:layout_marginEnd="16dp"
+				app:layout_constraintTop_toTopOf="parent"
-			android:layout_marginRight="16dp"
+				app:layout_constraintVertical_bias="0.25"
-			android:textColor="?android:attr/textColorPrimary"
+				app:layout_constraintVertical_chainStyle="packed"
-			android:textSize="@dimen/text_size_medium"
+				app:srcCompat="@drawable/qr_code_error"
-			app:layout_constraintBottom_toTopOf="@+id/sendFeedback"
+				app:tint="?attr/colorControlNormal"
-			app:layout_constraintEnd_toEndOf="parent"
+				tools:ignore="ContentDescription" />
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/errorIcon"
-			app:layout_constraintVertical_bias="0"
-			app:layout_constraintVertical_chainStyle="packed"
-			tools:text="error explanation" />
 
-		<TextView
+			<TextView
-			android:id="@+id/sendFeedback"
+				android:id="@+id/errorTitle"
-			android:layout_width="0dp"
+				android:layout_width="0dp"
-			android:layout_height="wrap_content"
+				android:layout_height="wrap_content"
-			android:layout_marginStart="16dp"
+				android:layout_marginTop="@dimen/margin_xlarge"
-			android:layout_marginLeft="16dp"
+				android:gravity="center"
-			android:layout_marginTop="8dp"
+				android:text="@string/connection_error_title"
-			android:layout_marginEnd="16dp"
+				android:textAppearance="@style/TextAppearance.MaterialComponents.Headline5"
-			android:layout_marginRight="16dp"
+				app:layout_constraintBottom_toTopOf="@+id/errorMessage"
-			android:text="@string/connection_error_feedback"
+				app:layout_constraintEnd_toEndOf="parent"
-			android:textColor="?android:attr/textColorPrimary"
+				app:layout_constraintStart_toStartOf="parent"
-			android:textSize="@dimen/text_size_medium"
+				app:layout_constraintTop_toBottomOf="@+id/errorIcon" />
-			app:layout_constraintBottom_toTopOf="@+id/tryAgainButton"
-			app:layout_constraintEnd_toEndOf="parent"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/errorMessage" />
 
-		<Button
+			<TextView
-			android:id="@+id/tryAgainButton"
+				android:id="@+id/errorMessage"
-			style="@style/BriarButtonFlat.Positive"
+				android:layout_width="0dp"
-			android:layout_width="0dp"
+				android:layout_height="wrap_content"
-			android:layout_height="wrap_content"
+				android:layout_marginTop="@dimen/margin_xlarge"
-			android:layout_marginEnd="8dp"
+				android:textAppearance="@style/TextAppearance.MaterialComponents.Body1"
-			android:layout_marginRight="8dp"
+				app:layout_constraintBottom_toTopOf="@+id/sendFeedback"
-			android:layout_marginBottom="8dp"
+				app:layout_constraintEnd_toEndOf="parent"
-			android:text="@string/try_again_button"
+				app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintBottom_toBottomOf="parent"
+				app:layout_constraintTop_toBottomOf="@+id/errorTitle"
-			app:layout_constraintEnd_toEndOf="parent"
+				tools:text="error explanation" />
-			app:layout_constraintHorizontal_weight="1"
-			app:layout_constraintStart_toEndOf="@+id/cancelButton" />
 
-		<Button
+			<TextView
-			android:id="@+id/cancelButton"
+				android:id="@+id/sendFeedback"
-			style="@style/BriarButtonFlat.Negative"
+				android:layout_width="0dp"
-			android:layout_width="0dp"
+				android:layout_height="wrap_content"
-			android:layout_height="wrap_content"
+				android:layout_marginTop="@dimen/margin_large"
-			android:layout_marginStart="8dp"
+				android:text="@string/connection_error_feedback"
-			android:layout_marginLeft="8dp"
+				android:textAppearance="@style/TextAppearance.MaterialComponents.Body1"
-			android:layout_marginEnd="8dp"
+				app:layout_constraintBottom_toBottomOf="parent"
-			android:layout_marginRight="8dp"
+				app:layout_constraintEnd_toEndOf="parent"
-			android:layout_marginBottom="8dp"
+				app:layout_constraintStart_toStartOf="parent"
-			android:text="@string/cancel"
+				app:layout_constraintTop_toBottomOf="@+id/errorMessage" />
-			app:layout_constraintBottom_toBottomOf="parent"
-			app:layout_constraintEnd_toStartOf="@+id/tryAgainButton"
-			app:layout_constraintHorizontal_chainStyle="spread"
-			app:layout_constraintHorizontal_weight="1"
-			app:layout_constraintStart_toStartOf="parent" />
 
-	</androidx.constraintlayout.widget.ConstraintLayout>
+		</androidx.constraintlayout.widget.ConstraintLayout>
-</ScrollView>
+
+	</androidx.core.widget.NestedScrollView>
+
+	<Button
+		android:id="@+id/cancelButton"
+		style="@style/BriarButtonFlat.Negative"
+		android:layout_width="0dp"
+		android:layout_height="wrap_content"
+		android:text="@string/cancel"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toStartOf="@+id/tryAgainButton"
+		app:layout_constraintHorizontal_weight="1"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="@+id/tryAgainButton" />
+
+	<Button
+		android:id="@+id/tryAgainButton"
+		style="@style/BriarButtonFlat.Positive"
+		android:layout_width="0dp"
+		android:layout_height="wrap_content"
+		android:text="@string/try_again_button"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintHorizontal_weight="1"
+		app:layout_constraintStart_toEndOf="@+id/cancelButton"
+		app:layout_constraintTop_toBottomOf="@+id/scrollView" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

briar-android/src/main/res/layout/fragment_final.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
+<androidx.core.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
 	xmlns:app="http://schemas.android.com/apk/res-auto"
 	xmlns:tools="http://schemas.android.com/tools"
 	android:layout_width="match_parent"
@@ -12,18 +12,16 @@
 
 		<ImageView
 			android:id="@+id/iconView"
-			android:layout_width="0dp"
+			android:layout_width="@dimen/hero_square"
-			android:layout_height="0dp"
+			android:layout_height="@dimen/hero_square"
-			android:layout_marginTop="32dp"
+			android:layout_marginHorizontal="@dimen/margin_xlarge"
+			android:layout_marginTop="@dimen/margin_xlarge"
 			app:layout_constraintBottom_toTopOf="@+id/titleView"
-			app:layout_constraintDimensionRatio="1:1"
 			app:layout_constraintEnd_toEndOf="parent"
 			app:layout_constraintStart_toStartOf="parent"
 			app:layout_constraintTop_toTopOf="parent"
 			app:layout_constraintVertical_bias="0.25"
 			app:layout_constraintVertical_chainStyle="packed"
-			app:layout_constraintWidth_max="200dp"
-			app:layout_constraintWidth_percent="0.4"
 			tools:ignore="ContentDescription"
 			tools:srcCompat="@drawable/alerts_and_states_error"
 			tools:tint="@color/briar_red_500" />
@@ -32,11 +30,8 @@
 			android:id="@+id/titleView"
 			android:layout_width="0dp"
 			android:layout_height="wrap_content"
-			android:layout_marginStart="32dp"
+			android:layout_marginHorizontal="@dimen/margin_xlarge"
-			android:layout_marginLeft="32dp"
+			android:layout_marginTop="@dimen/margin_xlarge"
-			android:layout_marginTop="32dp"
-			android:layout_marginEnd="32dp"
-			android:layout_marginRight="32dp"
 			android:gravity="center"
 			android:textAppearance="@style/TextAppearance.MaterialComponents.Headline5"
 			app:layout_constraintBottom_toTopOf="@+id/textView"
@@ -49,10 +44,9 @@
 			android:id="@+id/textView"
 			android:layout_width="0dp"
 			android:layout_height="wrap_content"
-			android:layout_marginStart="32dp"
+			android:layout_marginHorizontal="@dimen/margin_xlarge"
-			android:layout_marginTop="32dp"
+			android:layout_marginTop="@dimen/margin_xlarge"
-			android:layout_marginEnd="32dp"
+			android:layout_marginBottom="@dimen/margin_large"
-			android:layout_marginBottom="16dp"
 			android:textAppearance="@style/TextAppearance.MaterialComponents.Body1"
 			app:layout_constraintBottom_toTopOf="@+id/button"
 			app:layout_constraintEnd_toEndOf="parent"
@@ -65,7 +59,7 @@
 			style="@style/BriarButton"
 			android:layout_width="0dp"
 			android:layout_height="wrap_content"
-			android:layout_margin="16dp"
+			android:layout_margin="@dimen/margin_large"
 			android:text="@string/finish"
 			app:layout_constraintBottom_toBottomOf="parent"
 			app:layout_constraintEnd_toEndOf="parent"
@@ -73,4 +67,4 @@
 
 	</androidx.constraintlayout.widget.ConstraintLayout>
 
-</ScrollView>
+</androidx.core.widget.NestedScrollView>

briar-android/src/main/res/layout/fragment_hotspot_error.xml

@@ -73,7 +73,7 @@
 			app:layout_constraintEnd_toEndOf="parent"
 			app:layout_constraintStart_toStartOf="parent"
 			app:layout_constraintTop_toBottomOf="@+id/feedbackButton"
-			tools:layout="@layout/fragment_hotspot_save_apk" />
+			tools:layout="@layout/fragment_hotspot_fallback" />
 
 	</androidx.constraintlayout.widget.ConstraintLayout>
 

briar-android/src/main/res/layout/fragment_hotspot_fallback.xml

@@ -8,7 +8,7 @@
 		android:id="@id/fallbackTitleView"
 		android:layout_width="0dp"
 		android:layout_height="wrap_content"
-		android:layout_marginTop="32dp"
+		android:layout_marginTop="16dp"
 		android:text="@string/hotspot_help_fallback_title"
 		android:textSize="16sp"
 		android:textStyle="bold"

briar-android/src/main/res/layout/fragment_hotspot_help.xml

@@ -119,7 +119,7 @@
 			app:layout_constraintEnd_toEndOf="parent"
 			app:layout_constraintStart_toStartOf="parent"
 			app:layout_constraintTop_toBottomOf="@+id/site4View"
-			tools:layout="@layout/fragment_hotspot_save_apk" />
+			tools:layout="@layout/fragment_hotspot_fallback" />
 
 	</androidx.constraintlayout.widget.ConstraintLayout>
 

briar-android/src/main/res/layout/fragment_hotspot_intro.xml

@@ -1,86 +1,89 @@
 <?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
 	xmlns:app="http://schemas.android.com/apk/res-auto"
 	xmlns:tools="http://schemas.android.com/tools"
+	android:id="@+id/scrollView"
 	android:layout_width="match_parent"
 	android:layout_height="match_parent"
+	android:fillViewport="true"
 	tools:context=".android.hotspot.HotspotIntroFragment">
 
-	<ImageView
+	<androidx.constraintlayout.widget.ConstraintLayout
-		android:id="@+id/imageView"
+		android:layout_width="match_parent"
-		android:layout_width="0dp"
+		android:layout_height="wrap_content">
-		android:layout_height="0dp"
-		android:layout_marginStart="64dp"
-		android:layout_marginLeft="64dp"
-		android:layout_marginTop="32dp"
-		android:layout_marginEnd="64dp"
-		android:layout_marginRight="64dp"
-		android:layout_marginBottom="32dp"
-		app:layout_constraintBottom_toTopOf="@+id/introView"
-		app:layout_constraintDimensionRatio="1,1"
-		app:layout_constraintEnd_toEndOf="parent"
-		app:layout_constraintStart_toStartOf="parent"
-		app:layout_constraintTop_toTopOf="parent"
-		app:layout_constraintVertical_chainStyle="spread_inside"
-		app:srcCompat="@drawable/ic_nickname"
-		tools:ignore="ContentDescription" />
 
-	<TextView
+		<ImageView
-		android:id="@+id/introView"
+			android:id="@+id/imageView"
-		android:layout_width="0dp"
+			android:layout_width="@dimen/hero_square"
-		android:layout_height="wrap_content"
+			android:layout_height="@dimen/hero_square"
-		android:layout_margin="16dp"
+			android:layout_marginHorizontal="@dimen/margin_xlarge"
-		android:text="@string/hotspot_intro"
+			android:layout_marginTop="@dimen/margin_xlarge"
-		app:layout_constraintBottom_toTopOf="@+id/startButton"
+			app:layout_constraintBottom_toTopOf="@+id/introView"
-		app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintEnd_toEndOf="parent"
-		app:layout_constraintHorizontal_bias="0.5"
+			app:layout_constraintStart_toStartOf="parent"
-		app:layout_constraintStart_toStartOf="parent"
+			app:layout_constraintTop_toTopOf="parent"
-		app:layout_constraintTop_toBottomOf="@+id/imageView" />
+			app:layout_constraintVertical_bias="0.25"
+			app:layout_constraintVertical_chainStyle="packed"
+			app:srcCompat="@drawable/ic_wifi_tethering"
+			tools:ignore="ContentDescription" />
 
-	<Button
+		<TextView
-		android:id="@+id/startButton"
+			android:id="@+id/introView"
-		style="@style/BriarButton"
+			android:layout_width="0dp"
-		android:layout_width="0dp"
+			android:layout_height="wrap_content"
-		android:layout_height="wrap_content"
+			android:layout_marginHorizontal="@dimen/margin_xlarge"
-		android:layout_margin="16dp"
+			android:layout_marginTop="@dimen/margin_xlarge"
-		android:drawablePadding="6dp"
+			android:layout_marginBottom="@dimen/margin_large"
-		android:text="@string/hotspot_button_start_sharing"
+			android:text="@string/hotspot_intro"
-		app:drawableLeftCompat="@drawable/ic_wifi_tethering"
+			android:textAppearance="@style/TextAppearance.MaterialComponents.Body1"
-		app:drawableStartCompat="@drawable/ic_wifi_tethering"
+			app:layout_constraintBottom_toTopOf="@+id/startButton"
-		app:drawableTint="@color/button_text"
+			app:layout_constraintEnd_toEndOf="parent"
-		app:layout_constraintBottom_toBottomOf="parent"
+			app:layout_constraintStart_toStartOf="parent"
-		app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintTop_toBottomOf="@+id/imageView" />
-		app:layout_constraintHorizontal_bias="0.812"
-		app:layout_constraintStart_toStartOf="parent"
-		app:layout_constraintTop_toBottomOf="@+id/introView"
-		app:layout_constraintVertical_bias="1.0"
-		tools:visibility="visible" />
 
-	<ProgressBar
+		<Button
-		android:id="@+id/progressBar"
+			android:id="@+id/startButton"
-		style="?android:attr/progressBarStyle"
+			style="@style/BriarButton"
-		android:layout_width="wrap_content"
+			android:layout_width="0dp"
-		android:layout_height="wrap_content"
+			android:layout_height="wrap_content"
-		android:visibility="invisible"
+			android:layout_margin="@dimen/margin_large"
-		app:layout_constraintBottom_toBottomOf="@+id/startButton"
+			android:drawablePadding="8dp"
-		app:layout_constraintEnd_toStartOf="@+id/progressTextView"
+			android:text="@string/hotspot_button_start_sharing"
-		app:layout_constraintHorizontal_chainStyle="packed"
+			app:drawableLeftCompat="@drawable/ic_wifi_tethering"
-		app:layout_constraintStart_toStartOf="@+id/startButton"
+			app:drawableStartCompat="@drawable/ic_wifi_tethering"
-		app:layout_constraintTop_toTopOf="@+id/startButton"
+			app:drawableTint="@color/button_text"
-		tools:visibility="visible" />
+			app:layout_constraintBottom_toBottomOf="parent"
+			app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintStart_toStartOf="parent"
+			tools:visibility="visible" />
 
-	<TextView
+		<ProgressBar
-		android:id="@+id/progressTextView"
+			android:id="@+id/progressBar"
-		android:layout_width="wrap_content"
+			style="?android:attr/progressBarStyle"
-		android:layout_height="wrap_content"
+			android:layout_width="wrap_content"
-		android:layout_marginStart="16dp"
+			android:layout_height="wrap_content"
-		android:layout_marginLeft="16dp"
+			android:visibility="invisible"
-		android:text="@string/hotspot_progress_text_start"
+			app:layout_constraintBottom_toBottomOf="@+id/startButton"
-		android:visibility="invisible"
+			app:layout_constraintEnd_toStartOf="@+id/progressTextView"
-		app:layout_constraintBottom_toBottomOf="@+id/startButton"
+			app:layout_constraintHorizontal_chainStyle="packed"
-		app:layout_constraintEnd_toEndOf="@+id/startButton"
+			app:layout_constraintStart_toStartOf="@+id/startButton"
-		app:layout_constraintStart_toEndOf="@+id/progressBar"
+			app:layout_constraintTop_toTopOf="@+id/startButton"
-		app:layout_constraintTop_toTopOf="@+id/startButton"
+			tools:visibility="visible" />
-		tools:visibility="visible" />
 
-</androidx.constraintlayout.widget.ConstraintLayout>
+		<TextView
+			android:id="@+id/progressTextView"
+			android:layout_width="wrap_content"
+			android:layout_height="wrap_content"
+			android:layout_marginStart="@dimen/margin_large"
+			android:layout_marginLeft="@dimen/margin_large"
+			android:text="@string/hotspot_progress_text_start"
+			android:visibility="invisible"
+			app:layout_constraintBottom_toBottomOf="@+id/startButton"
+			app:layout_constraintEnd_toEndOf="@+id/startButton"
+			app:layout_constraintStart_toEndOf="@+id/progressBar"
+			app:layout_constraintTop_toTopOf="@+id/startButton"
+			tools:visibility="visible" />
+
+	</androidx.constraintlayout.widget.ConstraintLayout>
+
+</ScrollView>

briar-android/src/main/res/layout/fragment_hotspot_manual.xml

@@ -4,6 +4,7 @@
 	xmlns:tools="http://schemas.android.com/tools"
 	android:layout_width="match_parent"
 	android:layout_height="match_parent"
+	android:scrollbars="vertical"
 	android:fillViewport="true">
 
 	<androidx.constraintlayout.widget.ConstraintLayout
@@ -39,9 +40,9 @@
 			android:layout_marginTop="6dp"
 			android:layout_marginEnd="16dp"
 			android:layout_marginRight="16dp"
-			android:background="@color/briar_primary"
+			android:background="@android:color/white"
 			android:padding="8dp"
-			android:textColor="@color/briar_text_primary_inverse"
+			android:textColor="@color/briar_primary"
 			android:typeface="monospace"
 			app:layout_constraintEnd_toEndOf="parent"
 			app:layout_constraintStart_toStartOf="parent"
@@ -71,9 +72,9 @@
 			android:layout_marginTop="6dp"
 			android:layout_marginEnd="16dp"
 			android:layout_marginRight="16dp"
-			android:background="@color/briar_primary"
+			android:background="@android:color/white"
 			android:padding="8dp"
-			android:textColor="@color/briar_text_primary_inverse"
+			android:textColor="@color/briar_primary"
 			android:typeface="monospace"
 			app:layout_constraintEnd_toEndOf="parent"
 			app:layout_constraintStart_toStartOf="parent"

briar-android/src/main/res/layout/fragment_hotspot_qr.xml

@@ -4,6 +4,7 @@
 	xmlns:tools="http://schemas.android.com/tools"
 	android:layout_width="match_parent"
 	android:layout_height="match_parent"
+	android:scrollbars="vertical"
 	android:fillViewport="true">
 
 	<androidx.constraintlayout.widget.ConstraintLayout

briar-android/src/main/res/layout/fragment_hotspot_tabs.xml

@@ -6,9 +6,10 @@
 	android:layout_height="match_parent">
 
 	<androidx.coordinatorlayout.widget.CoordinatorLayout
+		android:id="@+id/coordinatorLayout"
 		android:layout_width="match_parent"
 		android:layout_height="0dp"
-		app:layout_constraintBottom_toTopOf="@+id/connectedButton"
+		app:layout_constraintBottom_toTopOf="@+id/connectedView"
 		app:layout_constraintEnd_toEndOf="parent"
 		app:layout_constraintStart_toStartOf="parent"
 		app:layout_constraintTop_toTopOf="parent">
@@ -51,20 +52,32 @@
 			android:id="@+id/pager"
 			android:layout_width="match_parent"
 			android:layout_height="match_parent"
-			app:layout_behavior="@string/appbar_scrolling_view_behavior"
+			app:layout_behavior="@string/appbar_scrolling_view_behavior" />
-			app:layout_constraintBottom_toTopOf="@+id/connectedButton"
-			app:layout_constraintEnd_toEndOf="parent"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/tabLayout" />
 
 	</androidx.coordinatorlayout.widget.CoordinatorLayout>
 
+	<TextView
+		android:id="@+id/connectedView"
+		android:layout_width="0dp"
+		android:layout_height="wrap_content"
+		android:layout_marginHorizontal="16dp"
+		android:layout_marginTop="6dp"
+		android:layout_marginBottom="1dp"
+		android:gravity="center"
+		android:text="@string/hotspot_no_peers_connected"
+		app:layout_constraintTop_toBottomOf="@+id/coordinatorLayout"
+		app:layout_constraintBottom_toTopOf="@+id/connectedButton"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent" />
+
 	<Button
 		android:id="@+id/connectedButton"
 		style="@style/BriarButton"
 		android:layout_width="0dp"
 		android:layout_height="wrap_content"
-		android:layout_margin="16dp"
+		android:layout_marginHorizontal="16dp"
+		android:layout_marginTop="1dp"
+		android:layout_marginBottom="1dp"
 		android:text="@string/hotspot_button_connected"
 		app:drawableLeftCompat="@drawable/ic_check_white"
 		app:drawableStartCompat="@drawable/ic_check_white"
@@ -79,7 +92,9 @@
 		style="@style/BriarButtonFlat.Negative"
 		android:layout_width="wrap_content"
 		android:layout_height="wrap_content"
-		android:layout_margin="16dp"
+		android:layout_marginHorizontal="16dp"
+		android:layout_marginTop="6dp"
+		android:layout_marginBottom="2dp"
 		android:drawablePadding="8dp"
 		android:text="@string/hotspot_button_stop_sharing"
 		app:drawableLeftCompat="@drawable/ic_portable_wifi_off"

briar-android/src/main/res/layout/fragment_onboarding_full.xml

@@ -4,6 +4,7 @@
 	xmlns:tools="http://schemas.android.com/tools"
 	android:layout_width="match_parent"
 	android:layout_height="match_parent"
+	android:background="@color/briar_primary"
 	android:orientation="vertical">
 
 	<androidx.appcompat.widget.Toolbar
@@ -12,30 +13,31 @@
 		android:layout_width="match_parent"
 		android:layout_height="wrap_content"
 		android:elevation="4dp"
-		app:layout_constraintEnd_toEndOf="parent"
-		app:layout_constraintStart_toStartOf="parent"
-		app:layout_constraintTop_toTopOf="parent"
 		app:navigationIcon="@drawable/abc_ic_ab_back_material"
 		tools:title="Onboarding Fullscreen Dialog" />
 
-	<ScrollView
+	<androidx.core.widget.NestedScrollView
 		android:layout_width="match_parent"
-		android:layout_height="match_parent"
+		android:layout_height="0dp"
-		android:background="@color/briar_primary"
+		android:layout_weight="1"
+		android:scrollbars="vertical"
 		android:fillViewport="true">
 
 		<androidx.constraintlayout.widget.ConstraintLayout
 			android:layout_width="match_parent"
-			android:layout_height="wrap_content">
+			android:layout_height="wrap_content"
+			android:layout_margin="@dimen/margin_xlarge">
 
 			<ImageView
 				android:id="@+id/imageView"
-				android:layout_width="64dp"
+				android:layout_width="@dimen/hero_square"
-				android:layout_height="64dp"
+				android:layout_height="@dimen/hero_square"
-				android:layout_margin="16dp"
+				app:layout_constraintBottom_toTopOf="@+id/contentView"
 				app:layout_constraintEnd_toEndOf="parent"
 				app:layout_constraintStart_toStartOf="parent"
 				app:layout_constraintTop_toTopOf="parent"
+				app:layout_constraintVertical_bias="0.25"
+				app:layout_constraintVertical_chainStyle="packed"
 				app:srcCompat="@drawable/ic_info_white"
 				app:tint="@color/briar_text_secondary_inverse"
 				tools:ignore="ContentDescription" />
@@ -44,26 +46,25 @@
 				android:id="@+id/contentView"
 				android:layout_width="0dp"
 				android:layout_height="wrap_content"
-				android:layout_margin="16dp"
+				android:layout_marginTop="@dimen/margin_xlarge"
+				android:textAppearance="@style/TextAppearance.MaterialComponents.Body1"
 				android:textColor="@color/briar_text_secondary_inverse"
-				app:layout_constraintBottom_toTopOf="@+id/button"
+				app:layout_constraintBottom_toBottomOf="parent"
 				app:layout_constraintEnd_toEndOf="parent"
 				app:layout_constraintStart_toStartOf="parent"
 				app:layout_constraintTop_toBottomOf="@+id/imageView"
-				app:layout_constraintVertical_bias="0.0"
 				tools:text="@tools:sample/lorem/random" />
 
-			<Button
-				android:id="@+id/button"
-				style="@style/BriarButtonFlat.Positive"
-				android:layout_width="wrap_content"
-				android:layout_height="wrap_content"
-				android:text="@string/got_it"
-				app:layout_constraintBottom_toBottomOf="parent"
-				app:layout_constraintEnd_toEndOf="parent" />
-
 		</androidx.constraintlayout.widget.ConstraintLayout>
 
-	</ScrollView>
+	</androidx.core.widget.NestedScrollView>
+
+	<Button
+		android:id="@+id/button"
+		style="@style/BriarButtonFlat.Positive"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_gravity="end"
+		android:text="@string/got_it" />
 
 </LinearLayout>

briar-android/src/main/res/layout/fragment_transfer_data_chooser.xml

@@ -12,16 +12,16 @@
 
 		<ImageView
 			android:id="@+id/imageView"
-			android:layout_width="0dp"
+			android:layout_width="@dimen/hero_square"
-			android:layout_height="0dp"
+			android:layout_height="@dimen/hero_square"
-			android:layout_marginTop="32dp"
+			android:layout_marginHorizontal="@dimen/margin_xlarge"
+			android:layout_marginTop="@dimen/margin_xlarge"
 			app:layout_constraintBottom_toTopOf="@+id/introView"
-			app:layout_constraintDimensionRatio="1,1"
 			app:layout_constraintEnd_toEndOf="parent"
 			app:layout_constraintStart_toStartOf="parent"
 			app:layout_constraintTop_toTopOf="parent"
-			app:layout_constraintVertical_chainStyle="spread"
+			app:layout_constraintVertical_bias="0.25"
-			app:layout_constraintWidth_percent="0.4"
+			app:layout_constraintVertical_chainStyle="packed"
 			app:srcCompat="@drawable/ic_transfer_data"
 			tools:ignore="ContentDescription" />
 
@@ -29,23 +29,37 @@
 			android:id="@+id/introView"
 			android:layout_width="0dp"
 			android:layout_height="wrap_content"
-			android:layout_marginStart="32dp"
+			android:layout_marginHorizontal="@dimen/margin_xlarge"
-			android:layout_marginTop="32dp"
+			android:layout_marginTop="@dimen/margin_xlarge"
-			android:layout_marginEnd="32dp"
-			android:layout_marginBottom="16dp"
 			android:text="@string/removable_drive_intro"
-			android:textSize="16sp"
+			android:textAppearance="@style/TextAppearance.MaterialComponents.Body1"
-			app:layout_constraintBottom_toTopOf="@+id/sendButton"
+			app:layout_constraintBottom_toTopOf="@+id/buttonLearnMore"
 			app:layout_constraintEnd_toEndOf="parent"
 			app:layout_constraintStart_toStartOf="parent"
 			app:layout_constraintTop_toBottomOf="@+id/imageView" />
 
+		<Button
+			android:id="@+id/buttonLearnMore"
+			style="@style/BriarButtonFlat.Positive"
+			android:layout_width="wrap_content"
+			android:layout_height="wrap_content"
+			android:layout_marginBottom="@dimen/margin_large"
+			android:padding="16dp"
+			android:text="@string/learn_more"
+			android:textAllCaps="false"
+			android:textSize="14sp"
+			app:layout_constraintBottom_toTopOf="@id/sendButton"
+			app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintStart_toStartOf="parent"
+			app:layout_constraintTop_toBottomOf="@+id/introView" />
+
 		<Button
 			android:id="@+id/sendButton"
 			style="@style/BriarButton"
 			android:layout_width="0dp"
 			android:layout_height="wrap_content"
-			android:layout_margin="16dp"
+			android:layout_marginHorizontal="@dimen/margin_large"
+			android:layout_marginTop="@dimen/margin_large"
 			android:text="@string/removable_drive_title_send"
 			app:layout_constraintBottom_toTopOf="@+id/receiveButton"
 			app:layout_constraintEnd_toEndOf="parent"
@@ -56,7 +70,7 @@
 			style="@style/BriarButton"
 			android:layout_width="0dp"
 			android:layout_height="wrap_content"
-			android:layout_margin="16dp"
+			android:layout_margin="@dimen/margin_large"
 			android:text="@string/removable_drive_title_receive"
 			app:layout_constraintBottom_toBottomOf="parent"
 			app:layout_constraintEnd_toEndOf="parent"

briar-android/src/main/res/layout/fragment_transfer_data_receive.xml

@@ -12,18 +12,17 @@
 
 		<ImageView
 			android:id="@+id/imageView"
-			android:layout_width="0dp"
+			android:layout_width="@dimen/hero_rect_width"
-			android:layout_height="0dp"
+			android:layout_height="@dimen/hero_rect_height"
-			android:layout_marginTop="32dp"
+			android:layout_marginHorizontal="@dimen/margin_xlarge"
+			android:layout_marginTop="@dimen/margin_xlarge"
 			app:layout_constraintBottom_toTopOf="@+id/progressBar"
-			app:layout_constraintDimensionRatio="1,2"
 			app:layout_constraintEnd_toEndOf="parent"
 			app:layout_constraintStart_toStartOf="parent"
 			app:layout_constraintTop_toTopOf="parent"
-			app:layout_constraintVertical_chainStyle="spread"
+			app:layout_constraintVertical_chainStyle="packed"
-			app:layout_constraintWidth_max="300dp"
+			app:layout_constraintVertical_bias="0.25"
-			app:layout_constraintWidth_percent="0.6"
+			app:srcCompat="@drawable/ic_transfer_data_receive"
-			app:srcCompat="@drawable/ic_transfer_data_send"
 			tools:ignore="ContentDescription" />
 
 		<ProgressBar
@@ -31,7 +30,8 @@
 			style="?android:attr/progressBarStyleHorizontal"
 			android:layout_width="0dp"
 			android:layout_height="wrap_content"
-			android:layout_margin="32dp"
+			android:layout_marginHorizontal="@dimen/margin_xlarge"
+			android:layout_marginTop="@dimen/margin_xlarge"
 			android:indeterminate="true"
 			android:visibility="invisible"
 			app:layout_constraintBottom_toTopOf="@+id/introTextView"
@@ -44,11 +44,11 @@
 			android:id="@+id/introTextView"
 			android:layout_width="0dp"
 			android:layout_height="wrap_content"
-			android:layout_marginStart="32dp"
+			android:layout_marginHorizontal="@dimen/margin_xlarge"
-			android:layout_marginEnd="32dp"
+			android:layout_marginTop="@dimen/margin_xlarge"
-			android:layout_marginBottom="16dp"
+			android:layout_marginBottom="@dimen/margin_large"
 			android:text="@string/removable_drive_receive_intro"
-			android:textSize="16sp"
+			android:textAppearance="@style/TextAppearance.MaterialComponents.Body1"
 			app:layout_constraintBottom_toTopOf="@+id/fileButton"
 			app:layout_constraintEnd_toEndOf="parent"
 			app:layout_constraintStart_toStartOf="parent"
@@ -59,7 +59,7 @@
 			style="@style/BriarButton"
 			android:layout_width="0dp"
 			android:layout_height="wrap_content"
-			android:layout_margin="16dp"
+			android:layout_margin="@dimen/margin_large"
 			android:enabled="false"
 			android:text="@string/removable_drive_receive_button"
 			app:layout_constraintBottom_toBottomOf="parent"