Replace events with return value and exceptions.

bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactExchangeManager.java

@@ -1,16 +1,24 @@
 package org.briarproject.bramble.api.contact;
 
 import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.db.ContactExistsException;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 
+import java.io.IOException;
+
 @NotNullByDefault
 public interface ContactExchangeManager {
 
 	/**
 	 * Exchanges contact information with a remote peer.
+	 *
+	 * @return The contact's pseudonym
+	 * @throws ContactExistsException If the contact already exists
 	 */
-	void exchangeContacts(TransportId t, DuplexTransportConnection conn,
-			SecretKey masterKey, boolean alice);
+	Author exchangeContacts(TransportId t, DuplexTransportConnection conn,
+			SecretKey masterKey, boolean alice) throws IOException, DbException;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/contact/event/ContactExchangeFailedEvent.java

@@ -1,32 +0,0 @@
-package org.briarproject.bramble.api.contact.event;
-
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.identity.Author;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import javax.annotation.Nullable;
-
-@NotNullByDefault
-public class ContactExchangeFailedEvent extends Event {
-
-	@Nullable
-	private final Author duplicateRemoteAuthor;
-
-	public ContactExchangeFailedEvent(@Nullable Author duplicateRemoteAuthor) {
-		this.duplicateRemoteAuthor = duplicateRemoteAuthor;
-	}
-
-	public ContactExchangeFailedEvent() {
-		this(null);
-	}
-
-	@Nullable
-	public Author getDuplicateRemoteAuthor() {
-		return duplicateRemoteAuthor;
-	}
-
-	public boolean wasDuplicateContact() {
-		return duplicateRemoteAuthor != null;
-	}
-
-}

bramble-api/src/main/java/org/briarproject/bramble/api/contact/event/ContactExchangeSucceededEvent.java

@@ -1,20 +0,0 @@
-package org.briarproject.bramble.api.contact.event;
-
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.identity.Author;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-@NotNullByDefault
-public class ContactExchangeSucceededEvent extends Event {
-
-	private final Author remoteAuthor;
-
-	public ContactExchangeSucceededEvent(Author remoteAuthor) {
-		this.remoteAuthor = remoteAuthor;
-	}
-
-	public Author getRemoteAuthor() {
-		return remoteAuthor;
-	}
-
-}

bramble-core/src/main/java/org/briarproject/bramble/contact/ContactExchangeManagerImpl.java

@@ -6,16 +6,12 @@ import org.briarproject.bramble.api.client.ClientHelper;
 import org.briarproject.bramble.api.contact.ContactExchangeManager;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
-import org.briarproject.bramble.api.contact.event.ContactExchangeFailedEvent;
-import org.briarproject.bramble.api.contact.event.ContactExchangeSucceededEvent;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.data.BdfDictionary;
 import org.briarproject.bramble.api.data.BdfList;
-import org.briarproject.bramble.api.db.ContactExistsException;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.identity.LocalAuthor;
@@ -46,7 +42,6 @@ import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
-import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.contact.RecordTypes.CONTACT_INFO;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_SIGNATURE_LENGTH;
@@ -56,7 +51,6 @@ import static org.briarproject.bramble.contact.ContactExchangeConstants.BOB_KEY_
 import static org.briarproject.bramble.contact.ContactExchangeConstants.BOB_NONCE_LABEL;
 import static org.briarproject.bramble.contact.ContactExchangeConstants.PROTOCOL_VERSION;
 import static org.briarproject.bramble.contact.ContactExchangeConstants.SIGNING_LABEL;
-import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.ValidationUtils.checkLength;
 import static org.briarproject.bramble.util.ValidationUtils.checkSize;
 
@@ -85,7 +79,6 @@ class ContactExchangeManagerImpl implements ContactExchangeManager {
 	private final ClientHelper clientHelper;
 	private final RecordReaderFactory recordReaderFactory;
 	private final RecordWriterFactory recordWriterFactory;
-	private final EventBus eventBus;
 	private final Clock clock;
 	private final ConnectionManager connectionManager;
 	private final ContactManager contactManager;
@@ -98,7 +91,7 @@ class ContactExchangeManagerImpl implements ContactExchangeManager {
 	@Inject
 	ContactExchangeManagerImpl(DatabaseComponent db, ClientHelper clientHelper,
 			RecordReaderFactory recordReaderFactory,
-			RecordWriterFactory recordWriterFactory, EventBus eventBus,
+			RecordWriterFactory recordWriterFactory,
 			Clock clock, ConnectionManager connectionManager,
 			ContactManager contactManager, IdentityManager identityManager,
 			TransportPropertyManager transportPropertyManager,
@@ -108,7 +101,6 @@ class ContactExchangeManagerImpl implements ContactExchangeManager {
 		this.clientHelper = clientHelper;
 		this.recordReaderFactory = recordReaderFactory;
 		this.recordWriterFactory = recordWriterFactory;
-		this.eventBus = eventBus;
 		this.clock = clock;
 		this.connectionManager = connectionManager;
 		this.contactManager = contactManager;
@@ -120,33 +112,17 @@ class ContactExchangeManagerImpl implements ContactExchangeManager {
 	}
 
 	@Override
-	public void exchangeContacts(TransportId t, DuplexTransportConnection conn,
-			SecretKey masterKey, boolean alice) {
+	public Author exchangeContacts(TransportId t,
+			DuplexTransportConnection conn, SecretKey masterKey, boolean alice)
+			throws IOException, DbException {
 		// Get the transport connection's input and output streams
-		InputStream in;
-		OutputStream out;
-		try {
-			in = conn.getReader().getInputStream();
-			out = conn.getWriter().getOutputStream();
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-			tryToClose(conn);
-			eventBus.broadcast(new ContactExchangeFailedEvent());
-			return;
-		}
+		InputStream in = conn.getReader().getInputStream();
+		OutputStream out = conn.getWriter().getOutputStream();
 
 		// Get the local author and transport properties
-		LocalAuthor localAuthor;
-		Map<TransportId, TransportProperties> localProperties;
-		try {
-			localAuthor = identityManager.getLocalAuthor();
-			localProperties = transportPropertyManager.getLocalProperties();
-		} catch (DbException e) {
-			logException(LOG, WARNING, e);
-			eventBus.broadcast(new ContactExchangeFailedEvent());
-			tryToClose(conn);
-			return;
-		}
+		LocalAuthor localAuthor = identityManager.getLocalAuthor();
+		Map<TransportId, TransportProperties> localProperties =
+				transportPropertyManager.getLocalProperties();
 
 		// Derive the header keys for the transport streams
 		SecretKey aliceHeaderKey = crypto.deriveKey(ALICE_KEY_LABEL, masterKey,
@@ -183,58 +159,37 @@ class ContactExchangeManagerImpl implements ContactExchangeManager {
 		// Exchange contact info
 		long localTimestamp = clock.currentTimeMillis();
 		ContactInfo remoteInfo;
-		try {
-			if (alice) {
-				sendContactInfo(recordWriter, localAuthor, localProperties,
-						localSignature, localTimestamp);
-				remoteInfo = receiveContactInfo(recordReader);
-			} else {
-				remoteInfo = receiveContactInfo(recordReader);
-				sendContactInfo(recordWriter, localAuthor, localProperties,
-						localSignature, localTimestamp);
-			}
-			// Send EOF on the outgoing stream
-			streamWriter.sendEndOfStream();
-			// Skip any remaining records from the incoming stream
-			recordReader.readRecord(r -> false, IGNORE);
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-			eventBus.broadcast(new ContactExchangeFailedEvent());
-			tryToClose(conn);
-			return;
+		if (alice) {
+			sendContactInfo(recordWriter, localAuthor, localProperties,
+					localSignature, localTimestamp);
+			remoteInfo = receiveContactInfo(recordReader);
+		} else {
+			remoteInfo = receiveContactInfo(recordReader);
+			sendContactInfo(recordWriter, localAuthor, localProperties,
+					localSignature, localTimestamp);
 		}
+		// Send EOF on the outgoing stream
+		streamWriter.sendEndOfStream();
+		// Skip any remaining records from the incoming stream
+		recordReader.readRecord(r -> false, IGNORE);
 
 		// Verify the contact's signature
 		if (!verify(remoteInfo.author, remoteNonce, remoteInfo.signature)) {
 			LOG.warning("Invalid signature");
-			eventBus.broadcast(new ContactExchangeFailedEvent());
-			tryToClose(conn);
-			return;
+			throw new FormatException();
 		}
 
 		// The agreed timestamp is the minimum of the peers' timestamps
 		long timestamp = Math.min(localTimestamp, remoteInfo.timestamp);
 
-		try {
-			// Add the contact
-			ContactId contactId = addContact(remoteInfo.author, localAuthor,
-					masterKey, timestamp, alice, remoteInfo.properties);
-			// Reuse the connection as a transport connection
-			connectionManager.manageOutgoingConnection(contactId, t, conn);
-			// Pseudonym exchange succeeded
-			LOG.info("Pseudonym exchange succeeded");
-			eventBus.broadcast(
-					new ContactExchangeSucceededEvent(remoteInfo.author));
-		} catch (ContactExistsException e) {
-			logException(LOG, WARNING, e);
-			tryToClose(conn);
-			eventBus.broadcast(
-					new ContactExchangeFailedEvent(e.getRemoteAuthor()));
-		} catch (DbException e) {
-			logException(LOG, WARNING, e);
-			tryToClose(conn);
-			eventBus.broadcast(new ContactExchangeFailedEvent());
-		}
+		// Add the contact
+		ContactId contactId = addContact(remoteInfo.author, localAuthor,
+				masterKey, timestamp, alice, remoteInfo.properties);
+		// Reuse the connection as a transport connection
+		connectionManager.manageOutgoingConnection(contactId, t, conn);
+		// Pseudonym exchange succeeded
+		LOG.info("Pseudonym exchange succeeded");
+		return remoteInfo.author;
 	}
 
 	private byte[] sign(LocalAuthor author, byte[] nonce) {
@@ -298,16 +253,6 @@ class ContactExchangeManagerImpl implements ContactExchangeManager {
 		});
 	}
 
-	private void tryToClose(DuplexTransportConnection conn) {
-		try {
-			LOG.info("Closing connection");
-			conn.getReader().dispose(true, true);
-			conn.getWriter().dispose(true);
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
-
 	private static class ContactInfo {
 
 		private final Author author;

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/ContactExchangeViewModel.java

@@ -7,58 +7,63 @@ import android.arch.lifecycle.MutableLiveData;
 import android.support.annotation.UiThread;
 
 import org.briarproject.bramble.api.contact.ContactExchangeManager;
-import org.briarproject.bramble.api.contact.event.ContactExchangeFailedEvent;
-import org.briarproject.bramble.api.contact.event.ContactExchangeSucceededEvent;
 import org.briarproject.bramble.api.crypto.SecretKey;
-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.db.ContactExistsException;
+import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 
+import java.io.IOException;
 import java.util.concurrent.Executor;
+import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
-import static java.util.Objects.requireNonNull;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
-class ContactExchangeViewModel extends AndroidViewModel
-		implements EventListener {
+class ContactExchangeViewModel extends AndroidViewModel {
+
+	private static final Logger LOG =
+			getLogger(ContactExchangeViewModel.class.getName());
 
 	private final Executor ioExecutor;
 	private final ContactExchangeManager contactExchangeManager;
-	private final EventBus eventBus;
 	private final MutableLiveData<Boolean> succeeded = new MutableLiveData<>();
 
 	@Nullable
-	private Author remoteAuthor, duplicateAuthor;
+	private volatile Author remoteAuthor, duplicateAuthor;
 
 	@Inject
 	ContactExchangeViewModel(Application app, @IoExecutor Executor ioExecutor,
-			ContactExchangeManager contactExchangeManager, EventBus eventBus) {
+			ContactExchangeManager contactExchangeManager) {
 		super(app);
 		this.ioExecutor = ioExecutor;
 		this.contactExchangeManager = contactExchangeManager;
-		this.eventBus = eventBus;
-		eventBus.addListener(this);
-	}
-
-	@Override
-	protected void onCleared() {
-		super.onCleared();
-		eventBus.removeListener(this);
 	}
 
 	@UiThread
 	void startContactExchange(TransportId t, DuplexTransportConnection conn,
 			SecretKey masterKey, boolean alice) {
-		ioExecutor.execute(() -> contactExchangeManager.exchangeContacts(t,
-				conn, masterKey, alice));
+		ioExecutor.execute(() -> {
+			try {
+				remoteAuthor = contactExchangeManager.exchangeContacts(t, conn,
+						masterKey, alice);
+				succeeded.postValue(true);
+			} catch (ContactExistsException e) {
+				duplicateAuthor = e.getRemoteAuthor();
+				succeeded.postValue(false);
+			} catch (DbException | IOException e) {
+				logException(LOG, WARNING, e);
+				succeeded.postValue(false);
+			}
+		});
 	}
 
 	@UiThread
@@ -76,18 +81,4 @@ class ContactExchangeViewModel extends AndroidViewModel
 	LiveData<Boolean> getSucceeded() {
 		return succeeded;
 	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof ContactExchangeSucceededEvent) {
-			ContactExchangeSucceededEvent c = (ContactExchangeSucceededEvent) e;
-			remoteAuthor = c.getRemoteAuthor();
-			succeeded.setValue(true);
-		} else if (e instanceof ContactExchangeFailedEvent) {
-			ContactExchangeFailedEvent c = (ContactExchangeFailedEvent) e;
-			if (c.wasDuplicateContact())
-				duplicateAuthor = requireNonNull(c.getDuplicateRemoteAuthor());
-			succeeded.setValue(false);
-		}
-	}
 }