Plan B: Remove error correction and reliability layers and the

consequent distinction between segments and frames.

api/net/sf/briar/api/crypto/CryptoComponent.java

@@ -9,10 +9,10 @@ import javax.crypto.Mac;
 
 public interface CryptoComponent {
 
-	ErasableKey deriveSegmentKey(byte[] secret, boolean initiator);
-
 	ErasableKey deriveTagKey(byte[] secret, boolean initiator);
 
+	ErasableKey deriveFrameKey(byte[] secret, boolean initiator);
+
 	ErasableKey deriveMacKey(byte[] secret, boolean initiator);
 
 	byte[] deriveNextSecret(byte[] secret, int index, long connection);
@@ -27,11 +27,11 @@ public interface CryptoComponent {
 
 	SecureRandom getSecureRandom();
 
-	Cipher getSegmentCipher();
+	Cipher getTagCipher();
+
+	Cipher getFrameCipher();
 
 	Signature getSignature();
 
-	Cipher getTagCipher();
-
 	Mac getMac();
 }

api/net/sf/briar/api/plugins/SegmentSink.java

-package net.sf.briar.api.plugins;
-
-import java.io.IOException;
-
-import net.sf.briar.api.transport.Segment;
-
-public interface SegmentSink {
-
-	/** Writes the given segment. */
-	void writeSegment(Segment s) throws IOException;
-
-	/**
-	 * Returns the maximum length in bytes of the segments this sink accepts.
-	 */
-	int getMaxSegmentLength();
-}

api/net/sf/briar/api/plugins/SegmentSource.java

-package net.sf.briar.api.plugins;
-
-import java.io.IOException;
-
-import net.sf.briar.api.transport.Segment;
-
-public interface SegmentSource {
-
-	/**
-	 * Attempts to read a segment into the given buffer and returns true if a
-	 * segment was read, or false if no more segments can be read.
-	 */
-	boolean readSegment(Segment s) throws IOException;
-
-	/**
-	 * Returns the maximum length in bytes of the segments this source returns.
-	 */
-	int getMaxSegmentLength();
-}

api/net/sf/briar/api/plugins/duplex/DuplexSegmentedPlugin.java

-package net.sf.briar.api.plugins.duplex;
-
-import net.sf.briar.api.ContactId;
-import net.sf.briar.api.plugins.Plugin;
-
-/**
- * An interface for transport plugins that support duplex segmented
- * communication.
- */
-public interface DuplexSegmentedPlugin extends Plugin {
-
-	/**
-	 * Attempts to create and return a connection to the given contact using
-	 * the current transport and configuration properties. Returns null if a
-	 * connection could not be created.
-	 */
-	DuplexSegmentedTransportConnection createConnection(ContactId c);
-
-	/**
-	 * Starts the invitation process from the inviter's side. Returns null if
-	 * no connection can be established within the given timeout.
-	 */
-	DuplexSegmentedTransportConnection sendInvitation(int code, long timeout);
-
-	/**
-	 * Starts the invitation process from the invitee's side. Returns null if
-	 * no connection can be established within the given timeout.
-	 */
-	DuplexSegmentedTransportConnection acceptInvitation(int code, long timeout);
-}

api/net/sf/briar/api/plugins/duplex/DuplexSegmentedPluginCallback.java

-package net.sf.briar.api.plugins.duplex;
-
-import net.sf.briar.api.ContactId;
-import net.sf.briar.api.plugins.PluginCallback;
-
-/**
- * An interface for handling connections created by a duplex segmented
- * transport plugin.
- */
-public interface DuplexSegmentedPluginCallback extends PluginCallback {
-
-	void incomingConnectionCreated(DuplexSegmentedTransportConnection d);
-
-	void outgoingConnectionCreated(ContactId c,
-			DuplexSegmentedTransportConnection d);
-
-}

api/net/sf/briar/api/plugins/duplex/DuplexSegmentedPluginFactory.java

-package net.sf.briar.api.plugins.duplex;
-
-import java.util.concurrent.Executor;
-
-public interface DuplexSegmentedPluginFactory {
-
-	DuplexSegmentedPlugin createPlugin(Executor pluginExecutor,
-			DuplexSegmentedPluginCallback callback);
-
-}

api/net/sf/briar/api/plugins/duplex/DuplexSegmentedTransportConnection.java

-package net.sf.briar.api.plugins.duplex;
-
-import net.sf.briar.api.plugins.SegmentSink;
-import net.sf.briar.api.plugins.SegmentSource;
-
-/**
- * An interface for reading and writing data over a duplex segmented transport.
- * The connection is not responsible for encrypting/decrypting or authenticating
- * the data.
- */
-public interface DuplexSegmentedTransportConnection extends SegmentSource,
-SegmentSink {
-
-	/** Returns the maximum length of a segment in bytes. */
-	int getMaximumSegmentLength();
-
-	/**
-	 * Returns true if the output stream should be flushed after each packet.
-	 */
-	boolean shouldFlush();
-
-	/**
-	 * Closes the connection and disposes of any associated resources. The
-	 * first argument indicates whether the connection is being closed because
-	 * of an exception and the second argument indicates whether the connection
-	 * was recognised, which may affect how resources are disposed of.
-	 */
-	void dispose(boolean exception, boolean recognised);
-}

api/net/sf/briar/api/plugins/simplex/SimplexSegmentedPlugin.java

-package net.sf.briar.api.plugins.simplex;
-
-import net.sf.briar.api.ContactId;
-import net.sf.briar.api.plugins.Plugin;
-
-/**
- * An interface for transport plugins that support simplex segmented
- * communication.
- */
-public interface SimplexSegmentedPlugin extends Plugin {
-
-	/**
-	 * Attempts to create and return a reader for the given contact using the
-	 * current transport and configuration properties. Returns null if a reader
-	 * could not be created.
-	 */
-	SimplexSegmentedTransportReader createReader(ContactId c);
-
-	/**
-	 * Attempts to create and return a writer for the given contact using the
-	 * current transport and configuration properties. Returns null if a writer
-	 * could not be created.
-	 */
-	SimplexSegmentedTransportWriter createWriter(ContactId c);
-
-	/**
-	 * Starts the invitation process from the inviter's side. Returns null if
-	 * no connection can be established within the given timeout.
-	 */
-	SimplexSegmentedTransportWriter sendInvitation(int code, long timeout);
-
-	/**
-	 * Starts the invitation process from the invitee's side. Returns null if
-	 * no connection can be established within the given timeout.
-	 */
-	SimplexSegmentedTransportReader acceptInvitation(int code, long timeout);
-
-	/**
-	 * Continues the invitation process from the invitee's side. Returns null
-	 * if no connection can be established within the given timeout.
-	 */
-	SimplexSegmentedTransportWriter sendInvitationResponse(int code,
-			long timeout);
-
-	/**
-	 * Continues the invitation process from the inviter's side. Returns null
-	 * if no connection can be established within the given timeout.
-	 */
-	SimplexSegmentedTransportReader acceptInvitationResponse(int code,
-			long timeout);
-}

api/net/sf/briar/api/plugins/simplex/SimplexSegmentedPluginCallback.java

-package net.sf.briar.api.plugins.simplex;
-
-import net.sf.briar.api.ContactId;
-import net.sf.briar.api.plugins.PluginCallback;
-
-/**
- * An interface for handling readers and writers created by a simplex
- * segmented transport plugin.
- */
-public interface SimplexSegmentedPluginCallback extends PluginCallback {
-
-	void readerCreated(SimplexSegmentedTransportReader r);
-
-	void writerCreated(ContactId c, SimplexSegmentedTransportWriter w);
-
-}

api/net/sf/briar/api/plugins/simplex/SimplexSegmentedPluginFactory.java

-package net.sf.briar.api.plugins.simplex;
-
-import java.util.concurrent.Executor;
-
-public interface SimplexSegmentedPluginFactory {
-
-	SimplexSegmentedPlugin createPlugin(Executor pluginExecutor,
-			SimplexSegmentedPluginCallback callback);
-}

api/net/sf/briar/api/plugins/simplex/SimplexSegmentedTransportReader.java

-package net.sf.briar.api.plugins.simplex;
-
-import net.sf.briar.api.plugins.SegmentSource;
-
-/**
- * An interface for reading data from a simplex segmented transport. The reader
- * is not responsible for decrypting or authenticating the data before
- * returning it.
- */
-public interface SimplexSegmentedTransportReader extends SegmentSource {
-
-	/**
-	 * Closes the reader and disposes of any associated resources. The first
-	 * argument indicates whether the reader is being closed because of an
-	 * exception and the second argument indicates whether the connection was
-	 * recognised, which may affect how resources are disposed of.
-	 */
-	void dispose(boolean exception, boolean recognised);
-}

api/net/sf/briar/api/plugins/simplex/SimplexSegmentedTransportWriter.java

-package net.sf.briar.api.plugins.simplex;
-
-import net.sf.briar.api.plugins.SegmentSink;
-
-/**
- * An interface for writing data to a simplex segmented transport. The writer is
- * not responsible for authenticating or encrypting the data before writing it.
- */
-public interface SimplexSegmentedTransportWriter extends SegmentSink {
-
-	/** Returns the capacity of the transport in bytes. */
-	long getCapacity();
-
-	/** Returns the maximum length of a segment in bytes. */
-	int getMaximumSegmentLength();
-
-	/**
-	 * Returns true if the output stream should be flushed after each packet.
-	 */
-	boolean shouldFlush();
-
-	/**
-	 * Closes the writer and disposes of any associated resources. The
-	 * argument indicates whether the writer is being closed because of an
-	 * exception, which may affect how resources are disposed of.
-	 */
-	void dispose(boolean exception);
-}

api/net/sf/briar/api/protocol/duplex/DuplexConnectionFactory.java

@@ -9,7 +9,7 @@ import net.sf.briar.api.transport.ConnectionContext;
 public interface DuplexConnectionFactory {
 
 	void createIncomingConnection(ConnectionContext ctx, TransportId t,
-			DuplexTransportConnection d, byte[] tag);
+			DuplexTransportConnection d);
 
 	void createOutgoingConnection(ContactId c, TransportId t, TransportIndex i,
 			DuplexTransportConnection d);

api/net/sf/briar/api/protocol/simplex/SimplexConnectionFactory.java

@@ -10,7 +10,7 @@ import net.sf.briar.api.transport.ConnectionContext;
 public interface SimplexConnectionFactory {
 
 	void createIncomingConnection(ConnectionContext ctx, TransportId t,
-			SimplexTransportReader r, byte[] tag);
+			SimplexTransportReader r);
 
 	void createOutgoingConnection(ContactId c, TransportId t, TransportIndex i,
 			SimplexTransportWriter w);

api/net/sf/briar/api/transport/ConnectionReaderFactory.java

@@ -2,35 +2,12 @@ package net.sf.briar.api.transport;
 
 import java.io.InputStream;
 
-import net.sf.briar.api.plugins.SegmentSource;
-
 public interface ConnectionReaderFactory {
 
 	/**
-	 * Creates a connection reader for a simplex connection or the initiator's
-	 * side of a duplex connection. The secret is erased before this method
-	 * returns.
+	 * Creates a connection reader for a simplex connection or one side of a
+	 * duplex connection. The secret is erased before this method returns.
 	 */
 	ConnectionReader createConnectionReader(InputStream in, byte[] secret,
-			byte[] bufferedTag);
-
-	/**
-	 * Creates a connection reader for a simplex connection or the initiator's
-	 * side of a duplex connection. The secret is erased before this method
-	 * returns.
-	 */
-	ConnectionReader createConnectionReader(SegmentSource in, byte[] secret,
-			Segment bufferedSegment);
-
-	/**
-	 * Creates a connection reader for the responder's side of a duplex
-	 * connection. The secret is erased before this method returns.
-	 */
-	ConnectionReader createConnectionReader(InputStream in, byte[] secret);
-
-	/**
-	 * Creates a connection reader for the responder's side of a duplex
-	 * connection. The secret is erased before this method returns.
-	 */
-	ConnectionReader createConnectionReader(SegmentSource in, byte[] secret);
+			boolean initiator);
 }

api/net/sf/briar/api/transport/ConnectionWriterFactory.java

@@ -2,8 +2,6 @@ package net.sf.briar.api.transport;
 
 import java.io.OutputStream;
 
-import net.sf.briar.api.plugins.SegmentSink;
-
 public interface ConnectionWriterFactory {
 
 	/**
@@ -12,11 +10,4 @@ public interface ConnectionWriterFactory {
 	 */
 	ConnectionWriter createConnectionWriter(OutputStream out, long capacity,
 			byte[] secret, boolean initiator);
-
-	/**
-	 * Creates a connection writer for a simplex connection or one side of a
-	 * duplex connection. The secret is erased before this method returns.
-	 */
-	ConnectionWriter createConnectionWriter(SegmentSink out, long capacity,
-			byte[] secret, boolean initiator);
 }

api/net/sf/briar/api/transport/Segment.java

-package net.sf.briar.api.transport;
-
-public interface Segment {
-
-	byte[] getBuffer();
-
-	int getLength();
-
-	long getSegmentNumber();
-
-	void setLength(int length);
-
-	void setSegmentNumber(long segmentNumber);
-}

api/net/sf/briar/api/transport/TransportConstants.java

@@ -2,21 +2,15 @@ package net.sf.briar.api.transport;
 
 public interface TransportConstants {
 
-	/** The maximum length of a segment in bytes, including the tag. */
-	static final int MAX_SEGMENT_LENGTH = 65536; // 2^16, 64 KiB
-
-	/** The length of the segment tag in bytes. */
+	/** The length of the connection tag in bytes. */
 	static final int TAG_LENGTH = 16;
 
 	/** The maximum length of a frame in bytes, including the header and MAC. */
-	static final int MAX_FRAME_LENGTH = MAX_SEGMENT_LENGTH - TAG_LENGTH;
+	static final int MAX_FRAME_LENGTH = 65536; // 2^16, 64 KiB
 
 	/** The length of the frame header in bytes. */
 	static final int FRAME_HEADER_LENGTH = 8;
 
-	/** The length of the ack header in bytes. */
-	static final int ACK_HEADER_LENGTH = 5;
-
 	/** The length of the MAC in bytes. */
 	static final int MAC_LENGTH = 32;
 
@@ -29,7 +23,4 @@ public interface TransportConstants {
 
 	/** The size of the connection reordering window. */
 	static final int CONNECTION_WINDOW_SIZE = 32;
-
-	/** The size of the frame reordering window. */
-	static final int FRAME_WINDOW_SIZE = 32;
 }

components/net/sf/briar/crypto/CryptoComponentImpl.java

@@ -33,12 +33,12 @@ class CryptoComponentImpl implements CryptoComponent {
 	private static final String DIGEST_ALGO = "SHA-256";
 	private static final String SIGNATURE_ALGO = "ECDSA";
 	private static final String TAG_CIPHER_ALGO = "AES/ECB/NoPadding";
-	private static final String SEGMENT_CIPHER_ALGO = "AES/CTR/NoPadding";
+	private static final String FRAME_CIPHER_ALGO = "AES/CTR/NoPadding";
 	private static final String MAC_ALGO = "HMacSHA256";
 
 	// Labels for key derivation, null-terminated
 	private static final byte[] TAG = { 'T', 'A', 'G', 0 };
-	private static final byte[] SEGMENT = { 'S', 'E', 'G', 0 };
+	private static final byte[] FRAME = { 'F', 'R', 'A', 'M', 'E', 0 };
 	private static final byte[] MAC = { 'M', 'A', 'C', 0 };
 	private static final byte[] NEXT = { 'N', 'E', 'X', 'T', 0 };
 	// Context strings for key derivation
@@ -71,9 +71,9 @@ class CryptoComponentImpl implements CryptoComponent {
 		else return deriveKey(secret, TAG, RESPONDER);
 	}
 
-	public ErasableKey deriveSegmentKey(byte[] secret, boolean initiator) {
-		if(initiator) return deriveKey(secret, SEGMENT, INITIATOR);
-		else return deriveKey(secret, SEGMENT, RESPONDER);
+	public ErasableKey deriveFrameKey(byte[] secret, boolean initiator) {
+		if(initiator) return deriveKey(secret, FRAME, INITIATOR);
+		else return deriveKey(secret, FRAME, RESPONDER);
 	}
 
 	public ErasableKey deriveMacKey(byte[] secret, boolean initiator) {
@@ -168,9 +168,9 @@ class CryptoComponentImpl implements CryptoComponent {
 		}
 	}
 
-	public Cipher getSegmentCipher() {
+	public Cipher getFrameCipher() {
 		try {
-			return Cipher.getInstance(SEGMENT_CIPHER_ALGO, PROVIDER);
+			return Cipher.getInstance(FRAME_CIPHER_ALGO, PROVIDER);
 		} catch(GeneralSecurityException e) {
 			throw new RuntimeException(e);
 		}

components/net/sf/briar/protocol/duplex/StreamConnectionFactoryImpl.java → components/net/sf/briar/protocol/duplex/DuplexConnectionFactoryImpl.java

@@ -19,7 +19,7 @@ import net.sf.briar.api.transport.ConnectionWriterFactory;
 
 import com.google.inject.Inject;
 
-class StreamConnectionFactoryImpl implements DuplexConnectionFactory {
+class DuplexConnectionFactoryImpl implements DuplexConnectionFactory {
 
 	private final Executor dbExecutor, verificationExecutor;
 	private final DatabaseComponent db;
@@ -30,7 +30,7 @@ class StreamConnectionFactoryImpl implements DuplexConnectionFactory {
 	private final ProtocolWriterFactory protoWriterFactory;
 
 	@Inject
-	StreamConnectionFactoryImpl(@DatabaseExecutor Executor dbExecutor,
+	DuplexConnectionFactoryImpl(@DatabaseExecutor Executor dbExecutor,
 			@VerificationExecutor Executor verificationExecutor,
 			DatabaseComponent db, ConnectionRegistry connRegistry,
 			ConnectionReaderFactory connReaderFactory,
@@ -48,11 +48,11 @@ class StreamConnectionFactoryImpl implements DuplexConnectionFactory {
 	}
 
 	public void createIncomingConnection(ConnectionContext ctx, TransportId t,
-			DuplexTransportConnection d, byte[] tag) {
+			DuplexTransportConnection d) {
 		final DuplexConnection conn = new IncomingDuplexConnection(dbExecutor,
 				verificationExecutor, db, connRegistry, connReaderFactory,
 				connWriterFactory, protoReaderFactory, protoWriterFactory,
-				ctx, t, d, tag);
+				ctx, t, d);
 		Runnable write = new Runnable() {
 			public void run() {
 				conn.write();