Address review comments

bramble-api/src/main/java/org/briarproject/bramble/api/sync/RecordReader.java

@@ -24,4 +24,5 @@ public interface RecordReader {
 	boolean hasRequest() throws IOException;
 
 	Request readRequest() throws IOException;
+
 }

bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncConstants.java

@@ -17,15 +17,10 @@ public interface SyncConstants {
 	/**
 	 * The maximum length of the record payload in bytes.
 	 */
-	int MAX_RECORD_PAYLOAD_LENGTH = 32 * 1024; // 32 KiB
+	int MAX_RECORD_PAYLOAD_LENGTH = 48 * 1024; // 48 KiB
 
 	/** The maximum length of a group descriptor in bytes. */
-	int MAX_GROUP_DESCRIPTOR_LENGTH = 32 * 1024; // 32 KiB
-
-	/**
-	 * The maximum length of a message in bytes.
-	 */
-	int MAX_MESSAGE_LENGTH = MAX_RECORD_PAYLOAD_LENGTH - RECORD_HEADER_LENGTH;
+	int MAX_GROUP_DESCRIPTOR_LENGTH = 16 * 1024; // 16 KiB
 
 	/**
 	 * The length of the message header in bytes.
@@ -37,6 +32,11 @@ public interface SyncConstants {
 	 */
 	int MAX_MESSAGE_BODY_LENGTH = 32 * 1024; // 32 KiB
 
+	/**
+	 * The maximum length of a message in bytes.
+	 */
+	int MAX_MESSAGE_LENGTH = MESSAGE_HEADER_LENGTH + MAX_MESSAGE_BODY_LENGTH;
+
 	/**
 	 * The maximum number of message IDs in an ack, offer or request record.
 	 */

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementTransport.java

@@ -96,37 +96,33 @@ class KeyAgreementTransport {
 	}
 
 	private byte[] readRecord(byte expectedType) throws AbortException {
-		byte[] header = readHeader();
-		int len = ByteUtils.readUint16(header,
-				RECORD_HEADER_PAYLOAD_LENGTH_OFFSET);
-		if (header[0] != PROTOCOL_VERSION) {
-			// ignore record with unknown protocol version and try next
+		while (true) {
+			byte[] header = readHeader();
+			int len = ByteUtils.readUint16(header,
+					RECORD_HEADER_PAYLOAD_LENGTH_OFFSET);
+			if (header[0] != PROTOCOL_VERSION) {
+				throw new AbortException(false);
+			}
+			byte type = header[1];
+			if (type == ABORT) throw new AbortException(true);
+			if (type != expectedType) {
+				if (type != KEY && type != CONFIRM) {
+					// ignore unrecognised record and try next
+					try {
+						readData(len);
+					} catch (IOException e) {
+						throw new AbortException(e);
+					}
+					continue;
+				} else {
+					throw new AbortException(false);
+				}
+			}
 			try {
-				readData(len);
+				return readData(len);
 			} catch (IOException e) {
 				throw new AbortException(e);
 			}
-			return readRecord(expectedType);
-		}
-		byte type = header[1];
-		if (type == ABORT) throw new AbortException(true);
-		if (type != expectedType) {
-			if (type != KEY && type != CONFIRM) {
-				// ignore unrecognised record and try next
-				try {
-					readData(len);
-				} catch (IOException e) {
-					throw new AbortException(e);
-				}
-				return readRecord(expectedType);
-			} else {
-				throw new AbortException(false);
-			}
-		}
-		try {
-			return readData(len);
-		} catch (IOException e) {
-			throw new AbortException(e);
 		}
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/sync/DuplexOutgoingSession.java

@@ -42,14 +42,14 @@ import static org.briarproject.bramble.api.sync.SyncConstants.MAX_RECORD_PAYLOAD
 /**
  * An outgoing {@link SyncSession} suitable for duplex transports. The session
  * offers messages before sending them, keeps its output stream open when there
- * are no packets to send, and reacts to events that make packets available to
+ * are no records to send, and reacts to events that make records available to
  * send.
  */
 @ThreadSafe
 @NotNullByDefault
 class DuplexOutgoingSession implements SyncSession, EventListener {
 
-	// Check for retransmittable packets once every 60 seconds
+	// Check for retransmittable records once every 60 seconds
 	private static final int RETX_QUERY_INTERVAL = 60 * 1000;
 	private static final Logger LOG =
 			Logger.getLogger(DuplexOutgoingSession.class.getName());
@@ -91,7 +91,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 	public void run() throws IOException {
 		eventBus.addListener(this);
 		try {
-			// Start a query for each type of packet
+			// Start a query for each type of record
 			dbExecutor.execute(new GenerateAck());
 			dbExecutor.execute(new GenerateBatch());
 			dbExecutor.execute(new GenerateOffer());
@@ -100,10 +100,10 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			long nextKeepalive = now + maxIdleTime;
 			long nextRetxQuery = now + RETX_QUERY_INTERVAL;
 			boolean dataToFlush = true;
-			// Write packets until interrupted
+			// Write records until interrupted
 			try {
 				while (!interrupted) {
-					// Work out how long we should wait for a packet
+					// Work out how long we should wait for a record
 					now = clock.currentTimeMillis();
 					long wait = Math.min(nextKeepalive, nextRetxQuery) - now;
 					if (wait < 0) wait = 0;
@@ -113,13 +113,13 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 						dataToFlush = false;
 						nextKeepalive = now + maxIdleTime;
 					}
-					// Wait for a packet
+					// Wait for a record
 					ThrowingRunnable<IOException> task = writerTasks.poll(wait,
 							MILLISECONDS);
 					if (task == null) {
 						now = clock.currentTimeMillis();
 						if (now >= nextRetxQuery) {
-							// Check for retransmittable packets
+							// Check for retransmittable records
 							dbExecutor.execute(new GenerateBatch());
 							dbExecutor.execute(new GenerateOffer());
 							nextRetxQuery = now + RETX_QUERY_INTERVAL;
@@ -139,7 +139,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 				}
 				if (dataToFlush) recordWriter.flush();
 			} catch (InterruptedException e) {
-				LOG.info("Interrupted while waiting for a packet to write");
+				LOG.info("Interrupted while waiting for a record to write");
 				Thread.currentThread().interrupt();
 			}
 		} finally {

bramble-core/src/main/java/org/briarproject/bramble/sync/IncomingSession.java

 package org.briarproject.bramble.sync;
 
+import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
 import org.briarproject.bramble.api.db.DatabaseComponent;
@@ -60,7 +61,7 @@ class IncomingSession implements SyncSession, EventListener {
 	public void run() throws IOException {
 		eventBus.addListener(this);
 		try {
-			// Read packets until interrupted or EOF
+			// Read records until interrupted or EOF
 			while (!interrupted && !recordReader.eof()) {
 				if (recordReader.hasAck()) {
 					Ack a = recordReader.readAck();
@@ -74,8 +75,10 @@ class IncomingSession implements SyncSession, EventListener {
 				} else if (recordReader.hasRequest()) {
 					Request r = recordReader.readRequest();
 					dbExecutor.execute(new ReceiveRequest(r));
+				} else {
+					// unknown records are ignored in RecordReader#eof()
+					throw new FormatException();
 				}
-				// unknown records are ignored
 			}
 		} finally {
 			eventBus.removeListener(this);

bramble-core/src/main/java/org/briarproject/bramble/sync/RecordReaderFactoryImpl.java

 package org.briarproject.bramble.sync;
 
-import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.sync.RecordReader;
@@ -15,13 +14,10 @@ import javax.inject.Inject;
 @NotNullByDefault
 class RecordReaderFactoryImpl implements RecordReaderFactory {
 
-	private final CryptoComponent crypto;
 	private final MessageFactory messageFactory;
 
 	@Inject
-	RecordReaderFactoryImpl(CryptoComponent crypto,
-			MessageFactory messageFactory) {
-		this.crypto = crypto;
+	RecordReaderFactoryImpl(MessageFactory messageFactory) {
 		this.messageFactory = messageFactory;
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/sync/RecordReaderImpl.java

@@ -51,32 +51,49 @@ class RecordReaderImpl implements RecordReader {
 
 	private void readRecord() throws IOException {
 		if (state != State.BUFFER_EMPTY) throw new IllegalStateException();
-		// Read the header
-		int offset = 0;
-		while (offset < RECORD_HEADER_LENGTH) {
-			int read = in.read(header, offset, RECORD_HEADER_LENGTH - offset);
-			if (read == -1) {
-				if (offset > 0) throw new FormatException();
-				state = State.EOF;
+		while (true) {
+			// Read the header
+			int offset = 0;
+			while (offset < RECORD_HEADER_LENGTH) {
+				int read =
+						in.read(header, offset, RECORD_HEADER_LENGTH - offset);
+				if (read == -1) {
+					if (offset > 0) throw new FormatException();
+					state = State.EOF;
+					return;
+				}
+				offset += read;
+			}
+			// Check the protocol version
+			if (header[0] != PROTOCOL_VERSION) throw new FormatException();
+			// Read the payload length
+			payloadLength = ByteUtils.readUint16(header, 2);
+			if (payloadLength > MAX_RECORD_PAYLOAD_LENGTH)
+				throw new FormatException();
+			// Read the payload
+			offset = 0;
+			while (offset < payloadLength) {
+				int read = in.read(payload, offset, payloadLength - offset);
+				if (read == -1) throw new FormatException();
+				offset += read;
+			}
+			state = State.BUFFER_FULL;
+			// Return if this is a known record type
+			if (header[1] == ACK || header[1] == MESSAGE ||
+					header[1] == OFFER || header[1] == REQUEST) {
 				return;
 			}
-			offset += read;
 		}
-		// Check the protocol version
-		if (header[0] != PROTOCOL_VERSION) throw new FormatException();
-		// Read the payload length
-		payloadLength = ByteUtils.readUint16(header, 2);
-		if (payloadLength > MAX_RECORD_PAYLOAD_LENGTH) throw new FormatException();
-		// Read the payload
-		offset = 0;
-		while (offset < payloadLength) {
-			int read = in.read(payload, offset, payloadLength - offset);
-			if (read == -1) throw new FormatException();
-			offset += read;
-		}
-		state = State.BUFFER_FULL;
 	}
 
+	/**
+	 * The return value indicates whether there's another record available
+	 * or whether we've reached the end of the input stream.
+	 * If a record is available,
+	 * it's been read into the buffer by the time eof() returns,
+	 * so the method that called eof() can access the record from the buffer,
+	 * for example to check its type or extract its payload.
+	 */
 	@Override
 	public boolean eof() throws IOException {
 		if (state == State.BUFFER_EMPTY) readRecord();
@@ -153,4 +170,5 @@ class RecordReaderImpl implements RecordReader {
 		if (!hasRequest()) throw new FormatException();
 		return new Request(readMessageIds());
 	}
+
 }

bramble-core/src/main/java/org/briarproject/bramble/sync/SimplexOutgoingSession.java

@@ -34,7 +34,7 @@ import static org.briarproject.bramble.api.sync.SyncConstants.MAX_RECORD_PAYLOAD
 /**
  * An outgoing {@link SyncSession} suitable for simplex transports. The session
  * sends messages without offering them first, and closes its output stream
- * when there are no more packets to send.
+ * when there are no more records to send.
  */
 @ThreadSafe
 @NotNullByDefault
@@ -70,7 +70,7 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 		this.contactId = contactId;
 		this.maxLatency = maxLatency;
 		this.recordWriter = recordWriter;
-		outstandingQueries = new AtomicInteger(2); // One per type of packet
+		outstandingQueries = new AtomicInteger(2); // One per type of record
 		writerTasks = new LinkedBlockingQueue<ThrowingRunnable<IOException>>();
 	}
 
@@ -79,10 +79,10 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 	public void run() throws IOException {
 		eventBus.addListener(this);
 		try {
-			// Start a query for each type of packet
+			// Start a query for each type of record
 			dbExecutor.execute(new GenerateAck());
 			dbExecutor.execute(new GenerateBatch());
-			// Write packets until interrupted or no more packets to write
+			// Write records until interrupted or no more records to write
 			try {
 				while (!interrupted) {
 					ThrowingRunnable<IOException> task = writerTasks.take();
@@ -91,7 +91,7 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 				}
 				recordWriter.flush();
 			} catch (InterruptedException e) {
-				LOG.info("Interrupted while waiting for a packet to write");
+				LOG.info("Interrupted while waiting for a record to write");
 				Thread.currentThread().interrupt();
 			}
 		} finally {

bramble-core/src/main/java/org/briarproject/bramble/sync/SyncModule.java

@@ -40,9 +40,9 @@ public class SyncModule {
 	}
 
 	@Provides
-	RecordReaderFactory provideRecordReaderFactory(CryptoComponent crypto,
-			MessageFactory messageFactory) {
-		return new RecordReaderFactoryImpl(crypto, messageFactory);
+	RecordReaderFactory provideRecordReaderFactory(
+			RecordReaderFactoryImpl recordReaderFactory) {
+		return recordReaderFactory;
 	}
 
 	@Provides