Implement backend for pairing mailbox

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxManager.java

@@ -0,0 +1,30 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+
+import javax.annotation.Nullable;
+
+public interface MailboxManager {
+
+	/**
+	 * @return true if a mailbox is already paired.
+	 */
+	boolean isPaired(Transaction txn) throws DbException;
+
+	/**
+	 * Returns the currently running pairing task,
+	 * or null if no pairing task is running.
+	 */
+	@Nullable
+	MailboxPairingTask getCurrentPairingTask();
+
+	/**
+	 * Starts and returns a pairing task. If a pairing task is already running,
+	 * it will be returned and the argument will be ignored.
+	 *
+	 * @param qrCodePayload The ISO-8859-1 encoded bytes of the mailbox QR code.
+	 */
+	MailboxPairingTask startPairingTask(String qrCodePayload);
+
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxPairingState.java

@@ -0,0 +1,59 @@
+package org.briarproject.bramble.api.mailbox;
+
+import javax.annotation.Nullable;
+
+public abstract class MailboxPairingState {
+
+	/**
+	 * The QR code payload that was scanned by the user.
+	 * This is null if the code should not be re-used anymore in this state.
+	 */
+	@Nullable
+	public final String qrCodePayload;
+
+	MailboxPairingState(@Nullable String qrCodePayload) {
+		this.qrCodePayload = qrCodePayload;
+	}
+
+	public static class QrCodeReceived extends MailboxPairingState {
+		public QrCodeReceived(String qrCodePayload) {
+			super(qrCodePayload);
+		}
+	}
+
+	public static class Pairing extends MailboxPairingState {
+		public Pairing(String qrCodePayload) {
+			super(qrCodePayload);
+		}
+	}
+
+	public static class Paired extends MailboxPairingState {
+		public Paired() {
+			super(null);
+		}
+	}
+
+	public static class InvalidQrCode extends MailboxPairingState {
+		public InvalidQrCode() {
+			super(null);
+		}
+	}
+
+	public static class MailboxAlreadyPaired extends MailboxPairingState {
+		public MailboxAlreadyPaired() {
+			super(null);
+		}
+	}
+
+	public static class ConnectionError extends MailboxPairingState {
+		public ConnectionError(String qrCodePayload) {
+			super(qrCodePayload);
+		}
+	}
+
+	public static class AssertionError extends MailboxPairingState {
+		public AssertionError(String qrCodePayload) {
+			super(qrCodePayload);
+		}
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxPairingTask.java

@@ -0,0 +1,21 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.Consumer;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public interface MailboxPairingTask extends Runnable {
+
+	/**
+	 * Adds an observer to the task. The observer will be notified on the
+	 * event thread of the current state of the task and any subsequent state
+	 * changes.
+	 */
+	void addObserver(Consumer<MailboxPairingState> observer);
+
+	/**
+	 * Removes an observer from the task.
+	 */
+	void removeObserver(Consumer<MailboxPairingState> observer);
+
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxApi.java

@@ -155,6 +155,10 @@ interface MailboxApi {
 	class ApiException extends Exception {
 	}
 
+	@Immutable
+	class MailboxAlreadyPairedException extends ApiException {
+	}
+
 	/**
 	 * A failure that does not need to be retried,
 	 * e.g. when adding a contact that already exists.

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxApiImpl.java

@@ -65,8 +65,7 @@ class MailboxApiImpl implements MailboxApi {
 				.build();
 		OkHttpClient client = httpClientProvider.get();
 		Response response = client.newCall(request).execute();
-		// TODO consider throwing a special exception for the 401 case
-		if (response.code() == 401) throw new ApiException();
+		if (response.code() == 401) throw new MailboxAlreadyPairedException();
 		if (!response.isSuccessful()) throw new ApiException();
 		ResponseBody body = response.body();
 		if (body == null) throw new ApiException();

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxManagerImpl.java

@@ -0,0 +1,72 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.mailbox.MailboxManager;
+import org.briarproject.bramble.api.mailbox.MailboxPairingTask;
+import org.briarproject.bramble.api.mailbox.MailboxSettingsManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.concurrent.Executor;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
+import javax.annotation.concurrent.Immutable;
+import javax.inject.Inject;
+
+@Immutable
+@NotNullByDefault
+class MailboxManagerImpl implements MailboxManager {
+
+	private final Executor ioExecutor;
+	private final MailboxSettingsManager mailboxSettingsManager;
+	private final MailboxPairingTaskFactory pairingTaskFactory;
+	private final Object lock = new Object();
+
+	@Nullable
+	@GuardedBy("lock")
+	private MailboxPairingTask pairingTask = null;
+
+	@Inject
+	MailboxManagerImpl(
+			@IoExecutor Executor ioExecutor,
+			MailboxSettingsManager mailboxSettingsManager,
+			MailboxPairingTaskFactory pairingTaskFactory) {
+		this.ioExecutor = ioExecutor;
+		this.mailboxSettingsManager = mailboxSettingsManager;
+		this.pairingTaskFactory = pairingTaskFactory;
+	}
+
+	@Override
+	public boolean isPaired(Transaction txn) throws DbException {
+		return mailboxSettingsManager.getOwnMailboxProperties(txn) != null;
+	}
+
+	@Nullable
+	@Override
+	public MailboxPairingTask getCurrentPairingTask() {
+		synchronized (lock) {
+			return pairingTask;
+		}
+	}
+
+	@Override
+	public MailboxPairingTask startPairingTask(String payload) {
+		MailboxPairingTask created;
+		synchronized (lock) {
+			if (pairingTask != null) return pairingTask;
+			created = pairingTaskFactory.createPairingTask(payload);
+			pairingTask = created;
+		}
+		ioExecutor.execute(() -> {
+			created.run();
+			synchronized (lock) {
+				// remove task after it finished
+				pairingTask = null;
+			}
+		});
+		return created;
+	}
+
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxModule.java

@@ -1,16 +1,36 @@
 package org.briarproject.bramble.mailbox;
 
+import org.briarproject.bramble.api.mailbox.MailboxManager;
 import org.briarproject.bramble.api.mailbox.MailboxSettingsManager;
 
+import javax.inject.Singleton;
+
 import dagger.Module;
 import dagger.Provides;
 
 @Module
 public class MailboxModule {
 
+	@Provides
+	@Singleton
+	MailboxManager providesMailboxManager(MailboxManagerImpl mailboxManager) {
+		return mailboxManager;
+	}
+
+	@Provides
+	MailboxPairingTaskFactory provideMailboxPairingTaskFactory(
+			MailboxPairingTaskFactoryImpl mailboxPairingTaskFactory) {
+		return mailboxPairingTaskFactory;
+	}
+
 	@Provides
 	MailboxSettingsManager provideMailboxSettingsManager(
 			MailboxSettingsManagerImpl mailboxSettingsManager) {
 		return mailboxSettingsManager;
 	}
+
+	@Provides
+	MailboxApi providesMailboxApi(MailboxApiImpl mailboxApi) {
+		return mailboxApi;
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxPairingTaskFactory.java

@@ -0,0 +1,12 @@
+package org.briarproject.bramble.mailbox;
+
+
+import org.briarproject.bramble.api.mailbox.MailboxPairingTask;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+interface MailboxPairingTaskFactory {
+
+	MailboxPairingTask createPairingTask(String qrCodePayload);
+
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxPairingTaskFactoryImpl.java

@@ -0,0 +1,44 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.event.EventExecutor;
+import org.briarproject.bramble.api.mailbox.MailboxPairingTask;
+import org.briarproject.bramble.api.mailbox.MailboxSettingsManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.concurrent.Executor;
+
+import javax.annotation.concurrent.Immutable;
+import javax.inject.Inject;
+
+@Immutable
+@NotNullByDefault
+class MailboxPairingTaskFactoryImpl implements MailboxPairingTaskFactory {
+
+	private final Executor eventExecutor;
+	private final TransactionManager db;
+	private final CryptoComponent crypto;
+	private final MailboxApi api;
+	private final MailboxSettingsManager mailboxSettingsManager;
+
+	@Inject
+	MailboxPairingTaskFactoryImpl(
+			@EventExecutor Executor eventExecutor,
+			TransactionManager db,
+			CryptoComponent crypto,
+			MailboxApi api,
+			MailboxSettingsManager mailboxSettingsManager) {
+		this.eventExecutor = eventExecutor;
+		this.db = db;
+		this.crypto = crypto;
+		this.api = api;
+		this.mailboxSettingsManager = mailboxSettingsManager;
+	}
+
+	@Override
+	public MailboxPairingTask createPairingTask(String qrCodePayload) {
+		return new MailboxPairingTaskImpl(qrCodePayload, eventExecutor, db,
+				crypto, api, mailboxSettingsManager);
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxPairingTaskImpl.java

@@ -0,0 +1,166 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.Consumer;
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.event.EventExecutor;
+import org.briarproject.bramble.api.mailbox.MailboxAuthToken;
+import org.briarproject.bramble.api.mailbox.MailboxPairingState;
+import org.briarproject.bramble.api.mailbox.MailboxPairingTask;
+import org.briarproject.bramble.api.mailbox.MailboxProperties;
+import org.briarproject.bramble.api.mailbox.MailboxSettingsManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.mailbox.MailboxApi.ApiException;
+import org.briarproject.bramble.mailbox.MailboxApi.MailboxAlreadyPairedException;
+
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.concurrent.GuardedBy;
+import javax.annotation.concurrent.ThreadSafe;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@ThreadSafe
+@NotNullByDefault
+class MailboxPairingTaskImpl implements MailboxPairingTask {
+
+	private final static Logger LOG =
+			getLogger(MailboxPairingTaskImpl.class.getName());
+	@SuppressWarnings("CharsetObjectCanBeUsed") // Requires minSdkVersion >= 19
+	private static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
+	private static final int VERSION_REQUIRED = 32;
+
+	private final String payload;
+	private final Executor eventExecutor;
+	private final TransactionManager db;
+	private final CryptoComponent crypto;
+	private final MailboxApi api;
+	private final MailboxSettingsManager mailboxSettingsManager;
+
+	private final Object lock = new Object();
+	@GuardedBy("lock")
+	private final List<Consumer<MailboxPairingState>> observers =
+			new ArrayList<>();
+	@GuardedBy("lock")
+	private MailboxPairingState state;
+
+	MailboxPairingTaskImpl(
+			String payload,
+			@EventExecutor Executor eventExecutor,
+			TransactionManager db,
+			CryptoComponent crypto,
+			MailboxApi api,
+			MailboxSettingsManager mailboxSettingsManager) {
+		this.payload = payload;
+		this.eventExecutor = eventExecutor;
+		this.db = db;
+		this.crypto = crypto;
+		this.api = api;
+		this.mailboxSettingsManager = mailboxSettingsManager;
+		state = new MailboxPairingState.QrCodeReceived(payload);
+	}
+
+	@Override
+	public void addObserver(Consumer<MailboxPairingState> o) {
+		MailboxPairingState state;
+		synchronized (lock) {
+			observers.add(o);
+			state = this.state;
+			eventExecutor.execute(() -> o.accept(state));
+		}
+	}
+
+	@Override
+	public void removeObserver(Consumer<MailboxPairingState> o) {
+		synchronized (lock) {
+			observers.remove(o);
+		}
+	}
+
+	@Override
+	public void run() {
+		try {
+			pairMailbox();
+		} catch (FormatException e) {
+			onMailboxError(e, new MailboxPairingState.InvalidQrCode());
+		} catch (MailboxAlreadyPairedException e) {
+			onMailboxError(e, new MailboxPairingState.MailboxAlreadyPaired());
+		} catch (IOException e) {
+			onMailboxError(e, new MailboxPairingState.ConnectionError(payload));
+		} catch (ApiException | DbException e) {
+			onMailboxError(e, new MailboxPairingState.AssertionError(payload));
+		}
+	}
+
+	private void pairMailbox() throws IOException, ApiException, DbException {
+		MailboxProperties mailboxProperties = decodeQrCodePayload(payload);
+		synchronized (lock) {
+			this.state = new MailboxPairingState.Pairing(payload);
+			notifyObservers();
+		}
+		MailboxAuthToken ownerToken = api.setup(mailboxProperties);
+		MailboxProperties ownerProperties = new MailboxProperties(
+				mailboxProperties.getOnionAddress(), ownerToken, true);
+		db.transaction(false, txn -> mailboxSettingsManager
+				.setOwnMailboxProperties(txn, ownerProperties));
+		synchronized (lock) {
+			this.state = new MailboxPairingState.Paired();
+			notifyObservers();
+		}
+		// TODO already do mailboxSettingsManager.setOwnMailboxStatus() ?
+	}
+
+	private void onMailboxError(Exception e, MailboxPairingState state) {
+		logException(LOG, WARNING, e);
+		synchronized (lock) {
+			this.state = state;
+			notifyObservers();
+		}
+	}
+
+	@GuardedBy("lock")
+	private void notifyObservers() {
+		List<Consumer<MailboxPairingState>> observers =
+				new ArrayList<>(this.observers);
+		MailboxPairingState state = this.state;
+		eventExecutor.execute(() -> {
+			for (Consumer<MailboxPairingState> o : observers) o.accept(state);
+		});
+	}
+
+	private MailboxProperties decodeQrCodePayload(String payload)
+			throws FormatException {
+		byte[] bytes = payload.getBytes(ISO_8859_1);
+		if (bytes.length != 65) {
+			if (LOG.isLoggable(WARNING)) {
+				LOG.warning("QR code length is not 65: " + bytes.length);
+			}
+			throw new FormatException();
+		}
+		int version = bytes[0] & 0xFF;
+		if (version != VERSION_REQUIRED) {
+			if (LOG.isLoggable(WARNING)) {
+				LOG.warning("QR code has not version " + VERSION_REQUIRED +
+						": " + version);
+			}
+			throw new FormatException();
+		}
+		LOG.info("QR code is valid");
+		byte[] onionPubKey = Arrays.copyOfRange(bytes, 1, 33);
+		String onionAddress = crypto.encodeOnionAddress(onionPubKey);
+		byte[] tokenBytes = Arrays.copyOfRange(bytes, 33, 65);
+		MailboxAuthToken setupToken = new MailboxAuthToken(tokenBytes);
+		return new MailboxProperties(onionAddress, setupToken, true);
+	}
+
+}