Split the functionality of ConnectionWriterImpl into layers.

components/net/sf/briar/transport/ConnectionReaderFactoryImpl.java

@@ -44,18 +44,18 @@ class ConnectionReaderFactoryImpl implements ConnectionReaderFactory {
 		// Create the decrypter
 		Cipher tagCipher = crypto.getTagCipher();
 		Cipher segCipher = crypto.getSegmentCipher();
-		IncomingEncryptionLayer decrypter = new IncomingEncryptionLayerImpl(in,
+		IncomingEncryptionLayer encryption = new IncomingEncryptionLayerImpl(in,
 				tagCipher, segCipher, tagKey, segKey, false, bufferedTag);
 		// No error correction
-		IncomingErrorCorrectionLayer correcter =
-			new NullIncomingErrorCorrectionLayer(decrypter);
+		IncomingErrorCorrectionLayer correction =
+			new NullIncomingErrorCorrectionLayer(encryption);
 		// Create the authenticator
 		Mac mac = crypto.getMac();
-		IncomingAuthenticationLayer authenticator =
-			new IncomingAuthenticationLayerImpl(correcter, mac, macKey);
+		IncomingAuthenticationLayer authentication =
+			new IncomingAuthenticationLayerImpl(correction, mac, macKey);
 		// No reordering or retransmission
 		IncomingReliabilityLayer reliability =
-			new NullIncomingReliabilityLayer(authenticator);
+			new NullIncomingReliabilityLayer(authentication);
 		// Create the reader - don't tolerate errors
 		return new ConnectionReaderImpl(reliability, false);
 	}
@@ -80,19 +80,19 @@ class ConnectionReaderFactoryImpl implements ConnectionReaderFactory {
 		// Create the decrypter
 		Cipher tagCipher = crypto.getTagCipher();
 		Cipher segCipher = crypto.getSegmentCipher();
-		IncomingEncryptionLayer decrypter =
+		IncomingEncryptionLayer encryption =
 			new IncomingSegmentedEncryptionLayer(in, tagCipher, segCipher,
 					tagKey, segKey, false, bufferedSegment);
 		// No error correction
-		IncomingErrorCorrectionLayer correcter =
-			new NullIncomingErrorCorrectionLayer(decrypter);
+		IncomingErrorCorrectionLayer correction =
+			new NullIncomingErrorCorrectionLayer(encryption);
 		// Create the authenticator
 		Mac mac = crypto.getMac();
-		IncomingAuthenticationLayer authenticator =
-			new IncomingAuthenticationLayerImpl(correcter, mac, macKey);
+		IncomingAuthenticationLayer authentication =
+			new IncomingAuthenticationLayerImpl(correction, mac, macKey);
 		// No reordering or retransmission
 		IncomingReliabilityLayer reliability =
-			new NullIncomingReliabilityLayer(authenticator);
+			new NullIncomingReliabilityLayer(authentication);
 		// Create the reader - don't tolerate errors
 		return new ConnectionReaderImpl(reliability, false);
 	}

components/net/sf/briar/transport/ConnectionWriterFactoryImpl.java

@@ -33,14 +33,20 @@ class ConnectionWriterFactoryImpl implements ConnectionWriterFactory {
 		// Create the encrypter
 		Cipher tagCipher = crypto.getTagCipher();
 		Cipher segCipher = crypto.getSegmentCipher();
-		OutgoingEncryptionLayer encrypter = new OutgoingEncryptionLayerImpl(out,
-				capacity, tagCipher, segCipher, tagKey, segKey, false);
+		OutgoingEncryptionLayer encryption = new OutgoingEncryptionLayerImpl(
+				out, capacity, tagCipher, segCipher, tagKey, segKey, false);
 		// No error correction
-		OutgoingErrorCorrectionLayer correcter =
-			new NullOutgoingErrorCorrectionLayer(encrypter);
-		// Create the writer
+		OutgoingErrorCorrectionLayer correction =
+			new NullOutgoingErrorCorrectionLayer(encryption);
+		// Authentication
 		Mac mac = crypto.getMac();
-		return new ConnectionWriterImpl(correcter, mac, macKey);
+		OutgoingAuthenticationLayer authentication =
+			new OutgoingAuthenticationLayerImpl(correction, mac, macKey);
+		// No retransmission
+		OutgoingReliabilityLayer reliability =
+			new NullOutgoingReliabilityLayer(authentication);
+		// Create the writer
+		return new ConnectionWriterImpl(reliability);
 	}
 
 	public ConnectionWriter createConnectionWriter(SegmentSink out,
@@ -53,14 +59,20 @@ class ConnectionWriterFactoryImpl implements ConnectionWriterFactory {
 		// Create the encrypter
 		Cipher tagCipher = crypto.getTagCipher();
 		Cipher segCipher = crypto.getSegmentCipher();
-		OutgoingEncryptionLayer encrypter =
+		OutgoingEncryptionLayer encryption =
 			new OutgoingSegmentedEncryptionLayer(out, capacity, tagCipher,
 					segCipher, tagKey, segKey, false);
 		// No error correction
-		OutgoingErrorCorrectionLayer correcter =
-			new NullOutgoingErrorCorrectionLayer(encrypter);
-		// Create the writer
+		OutgoingErrorCorrectionLayer correction =
+			new NullOutgoingErrorCorrectionLayer(encryption);
+		// Authentication
 		Mac mac = crypto.getMac();
-		return new ConnectionWriterImpl(correcter, mac, macKey);
+		OutgoingAuthenticationLayer authentication =
+			new OutgoingAuthenticationLayerImpl(correction, mac, macKey);
+		// No retransmission
+		OutgoingReliabilityLayer reliability =
+			new NullOutgoingReliabilityLayer(authentication);
+		// Create the writer
+		return new ConnectionWriterImpl(reliability);
 	}
 }

components/net/sf/briar/transport/ConnectionWriterImpl.java

@@ -7,12 +7,7 @@ import static net.sf.briar.util.ByteUtils.MAX_32_BIT_UNSIGNED;
 
 import java.io.IOException;
 import java.io.OutputStream;
-import java.security.InvalidKeyException;
 
-import javax.crypto.Mac;
-import javax.crypto.ShortBufferException;
-
-import net.sf.briar.api.crypto.ErasableKey;
 import net.sf.briar.api.transport.ConnectionWriter;
 
 /**
@@ -23,26 +18,14 @@ import net.sf.briar.api.transport.ConnectionWriter;
  */
 class ConnectionWriterImpl extends OutputStream implements ConnectionWriter {
 
-	private final OutgoingErrorCorrectionLayer out;
-	private final Mac mac;
+	private final OutgoingReliabilityLayer out;
 	private final Frame frame;
 
 	private int offset = FRAME_HEADER_LENGTH;
 	private long frameNumber = 0L;
 
-	ConnectionWriterImpl(OutgoingErrorCorrectionLayer out, Mac mac,
-			ErasableKey macKey) {
+	ConnectionWriterImpl(OutgoingReliabilityLayer out) {
 		this.out = out;
-		this.mac = mac;
-		// Initialise the MAC
-		try {
-			mac.init(macKey);
-		} catch(InvalidKeyException badKey) {
-			throw new IllegalArgumentException(badKey);
-		}
-		macKey.erase();
-		if(mac.getMacLength() != MAC_LENGTH)
-			throw new IllegalArgumentException();
 		frame = new Frame();
 	}
 
@@ -96,16 +79,9 @@ class ConnectionWriterImpl extends OutputStream implements ConnectionWriter {
 
 	private void writeFrame() throws IOException {
 		if(frameNumber > MAX_32_BIT_UNSIGNED) throw new IllegalStateException();
-		byte[] buf = frame.getBuffer();
-		int payloadLength = offset - FRAME_HEADER_LENGTH;
-		assert payloadLength > 0;
-		HeaderEncoder.encodeHeader(buf, frameNumber, payloadLength, 0);
-		mac.update(buf, 0, offset);
-		try {
-			mac.doFinal(buf, offset);
-		} catch(ShortBufferException badMac) {
-			throw new RuntimeException(badMac);
-		}
+		int payload = offset - FRAME_HEADER_LENGTH;
+		assert payload > 0;
+		HeaderEncoder.encodeHeader(frame.getBuffer(), frameNumber, payload, 0);
 		frame.setLength(offset + MAC_LENGTH);
 		out.writeFrame(frame);
 		offset = FRAME_HEADER_LENGTH;

components/net/sf/briar/transport/NullOutgoingReliabilityLayer.java

@@ -0,0 +1,24 @@
+package net.sf.briar.transport;
+
+import java.io.IOException;
+
+class NullOutgoingReliabilityLayer implements OutgoingReliabilityLayer {
+
+	private final OutgoingAuthenticationLayer out;
+
+	NullOutgoingReliabilityLayer(OutgoingAuthenticationLayer out) {
+		this.out = out;
+	}
+
+	public void writeFrame(Frame f) throws IOException {
+		out.writeFrame(f);
+	}
+
+	public void flush() throws IOException {
+		out.flush();
+	}
+
+	public long getRemainingCapacity() {
+		return out.getRemainingCapacity();
+	}
+}

components/net/sf/briar/transport/OutgoingAuthenticationLayer.java

@@ -0,0 +1,15 @@
+package net.sf.briar.transport;
+
+import java.io.IOException;
+
+interface OutgoingAuthenticationLayer {
+
+	/** Writes the given frame. */
+	void writeFrame(Frame f) throws IOException;
+
+	/** Flushes the stack. */
+	void flush() throws IOException;
+
+	/** Returns the maximum number of bytes that can be written. */
+	long getRemainingCapacity();
+}

components/net/sf/briar/transport/OutgoingAuthenticationLayerImpl.java

@@ -0,0 +1,52 @@
+package net.sf.briar.transport;
+
+import static net.sf.briar.api.transport.TransportConstants.MAC_LENGTH;
+
+import java.io.IOException;
+import java.security.InvalidKeyException;
+
+import javax.crypto.Mac;
+import javax.crypto.ShortBufferException;
+
+import net.sf.briar.api.crypto.ErasableKey;
+
+class OutgoingAuthenticationLayerImpl implements OutgoingAuthenticationLayer {
+
+	private final OutgoingErrorCorrectionLayer out;
+	private final Mac mac;
+
+	OutgoingAuthenticationLayerImpl(OutgoingErrorCorrectionLayer out, Mac mac,
+			ErasableKey macKey) {
+		this.out = out;
+		this.mac = mac;
+		// Initialise the MAC
+		try {
+			mac.init(macKey);
+		} catch(InvalidKeyException badKey) {
+			throw new IllegalArgumentException(badKey);
+		}
+		macKey.erase();
+		if(mac.getMacLength() != MAC_LENGTH)
+			throw new IllegalArgumentException();
+	}
+
+	public void writeFrame(Frame f) throws IOException {
+		byte[] buf = f.getBuffer();
+		int length = f.getLength() - MAC_LENGTH;
+		mac.update(buf, 0, length);
+		try {
+			mac.doFinal(buf, length);
+		} catch(ShortBufferException badMac) {
+			throw new RuntimeException(badMac);
+		}
+		out.writeFrame(f);
+	}
+
+	public void flush() throws IOException {
+		out.flush();
+	}
+
+	public long getRemainingCapacity() {
+		return out.getRemainingCapacity();
+	}
+}

components/net/sf/briar/transport/OutgoingReliabilityLayer.java

@@ -0,0 +1,15 @@
+package net.sf.briar.transport;
+
+import java.io.IOException;
+
+interface OutgoingReliabilityLayer {
+
+	/** Writes the given frame. */
+	void writeFrame(Frame f) throws IOException;
+
+	/** Flushes the stack. */
+	void flush() throws IOException;
+
+	/** Returns the maximum number of bytes that can be written. */
+	long getRemainingCapacity();
+}

test/net/sf/briar/transport/ConnectionReaderImplTest.java

@@ -217,13 +217,14 @@ public class ConnectionReaderImplTest extends TransportTest {
 	}
 
 	private ConnectionReader createConnectionReader(InputStream in) {
-		IncomingEncryptionLayer decrypter = new NullIncomingEncryptionLayer(in);
-		IncomingErrorCorrectionLayer correcter =
-			new NullIncomingErrorCorrectionLayer(decrypter);
-		IncomingAuthenticationLayer authenticator =
-			new IncomingAuthenticationLayerImpl(correcter, mac, macKey);
+		IncomingEncryptionLayer encryption =
+			new NullIncomingEncryptionLayer(in);
+		IncomingErrorCorrectionLayer correction =
+			new NullIncomingErrorCorrectionLayer(encryption);
+		IncomingAuthenticationLayer authentication =
+			new IncomingAuthenticationLayerImpl(correction, mac, macKey);
 		IncomingReliabilityLayer reliability =
-			new NullIncomingReliabilityLayer(authenticator);
+			new NullIncomingReliabilityLayer(authentication);
 		return new ConnectionReaderImpl(reliability, false);
 	}
 }

test/net/sf/briar/transport/ConnectionWriterImplTest.java

@@ -12,6 +12,7 @@ import net.sf.briar.api.transport.ConnectionWriter;
 
 import org.junit.Test;
 
+// FIXME: This test covers too many classes
 public class ConnectionWriterImplTest extends TransportTest {
 
 	public ConnectionWriterImplTest() throws Exception {
@@ -21,11 +22,7 @@ public class ConnectionWriterImplTest extends TransportTest {
 	@Test
 	public void testFlushWithoutWriteProducesNothing() throws Exception {
 		ByteArrayOutputStream out = new ByteArrayOutputStream();
-		OutgoingEncryptionLayer encrypter =
-			new NullOutgoingEncryptionLayer(out);
-		OutgoingErrorCorrectionLayer correcter =
-			new NullOutgoingErrorCorrectionLayer(encrypter);
-		ConnectionWriter w = new ConnectionWriterImpl(correcter, mac, macKey);
+		ConnectionWriter w = createConnectionWriter(out);
 		w.getOutputStream().flush();
 		w.getOutputStream().flush();
 		w.getOutputStream().flush();
@@ -44,11 +41,7 @@ public class ConnectionWriterImplTest extends TransportTest {
 		mac.doFinal(frame, FRAME_HEADER_LENGTH + payloadLength);
 		// Check that the ConnectionWriter gets the same results
 		ByteArrayOutputStream out = new ByteArrayOutputStream();
-		OutgoingEncryptionLayer encrypter =
-			new NullOutgoingEncryptionLayer(out);
-		OutgoingErrorCorrectionLayer correcter =
-			new NullOutgoingErrorCorrectionLayer(encrypter);
-		ConnectionWriter w = new ConnectionWriterImpl(correcter, mac, macKey);
+		ConnectionWriter w = createConnectionWriter(out);
 		w.getOutputStream().write(0);
 		w.getOutputStream().flush();
 		assertArrayEquals(frame, out.toByteArray());
@@ -57,11 +50,7 @@ public class ConnectionWriterImplTest extends TransportTest {
 	@Test
 	public void testWriteByteToMaxLengthWritesFrame() throws Exception {
 		ByteArrayOutputStream out = new ByteArrayOutputStream();
-		OutgoingEncryptionLayer encrypter =
-			new NullOutgoingEncryptionLayer(out);
-		OutgoingErrorCorrectionLayer correcter =
-			new NullOutgoingErrorCorrectionLayer(encrypter);
-		ConnectionWriter w = new ConnectionWriterImpl(correcter, mac, macKey);
+		ConnectionWriter w = createConnectionWriter(out);
 		OutputStream out1 = w.getOutputStream();
 		// The first maxPayloadLength - 1 bytes should be buffered
 		for(int i = 0; i < MAX_PAYLOAD_LENGTH - 1; i++) out1.write(0);
@@ -74,11 +63,7 @@ public class ConnectionWriterImplTest extends TransportTest {
 	@Test
 	public void testWriteArrayToMaxLengthWritesFrame() throws Exception {
 		ByteArrayOutputStream out = new ByteArrayOutputStream();
-		OutgoingEncryptionLayer encrypter =
-			new NullOutgoingEncryptionLayer(out);
-		OutgoingErrorCorrectionLayer correcter =
-			new NullOutgoingErrorCorrectionLayer(encrypter);
-		ConnectionWriter w = new ConnectionWriterImpl(correcter, mac, macKey);
+		ConnectionWriter w = createConnectionWriter(out);
 		OutputStream out1 = w.getOutputStream();
 		// The first maxPayloadLength - 1 bytes should be buffered
 		out1.write(new byte[MAX_PAYLOAD_LENGTH - 1]);
@@ -112,11 +97,7 @@ public class ConnectionWriterImplTest extends TransportTest {
 		byte[] expected = out.toByteArray();
 		// Check that the ConnectionWriter gets the same results
 		out.reset();
-		OutgoingEncryptionLayer encrypter =
-			new NullOutgoingEncryptionLayer(out);
-		OutgoingErrorCorrectionLayer correcter =
-			new NullOutgoingErrorCorrectionLayer(encrypter);
-		ConnectionWriter w = new ConnectionWriterImpl(correcter, mac, macKey);
+		ConnectionWriter w = createConnectionWriter(out);
 		w.getOutputStream().write(new byte[123]);
 		w.getOutputStream().flush();
 		w.getOutputStream().write(new byte[1234]);
@@ -124,4 +105,16 @@ public class ConnectionWriterImplTest extends TransportTest {
 		byte[] actual = out.toByteArray();
 		assertArrayEquals(expected, actual);
 	}
+
+	private ConnectionWriter createConnectionWriter(OutputStream out) {
+		OutgoingEncryptionLayer encryption =
+			new NullOutgoingEncryptionLayer(out);
+		OutgoingErrorCorrectionLayer correction =
+			new NullOutgoingErrorCorrectionLayer(encryption);
+		OutgoingAuthenticationLayer authentication =
+			new OutgoingAuthenticationLayerImpl(correction, mac, macKey);
+		OutgoingReliabilityLayer reliability =
+			new NullOutgoingReliabilityLayer(authentication);
+		return new ConnectionWriterImpl(reliability);
+	}
 }

test/net/sf/briar/transport/FrameReadWriteTest.java

@@ -74,13 +74,16 @@ public class FrameReadWriteTest extends BriarTestCase {
 		ErasableKey macCopy = macKey.copy();
 		// Write the frames
 		ByteArrayOutputStream out = new ByteArrayOutputStream();
-		OutgoingEncryptionLayer encrypter = new OutgoingEncryptionLayerImpl(out,
-				Long.MAX_VALUE, tagCipher, segCipher, tagCopy, segCopy,
+		OutgoingEncryptionLayer encryptionOut = new OutgoingEncryptionLayerImpl(
+				out, Long.MAX_VALUE, tagCipher, segCipher, tagCopy, segCopy,
 				false);
-		OutgoingErrorCorrectionLayer correcter =
-			new NullOutgoingErrorCorrectionLayer(encrypter);
-		ConnectionWriter writer = new ConnectionWriterImpl(correcter, mac,
-				macCopy);
+		OutgoingErrorCorrectionLayer correctionOut =
+			new NullOutgoingErrorCorrectionLayer(encryptionOut);
+		OutgoingAuthenticationLayer authenticationOut =
+			new OutgoingAuthenticationLayerImpl(correctionOut, mac, macCopy);
+		OutgoingReliabilityLayer reliabilityOut =
+			new NullOutgoingReliabilityLayer(authenticationOut);
+		ConnectionWriter writer = new ConnectionWriterImpl(reliabilityOut);
 		OutputStream out1 = writer.getOutputStream();
 		out1.write(frame);
 		out1.flush();
@@ -93,15 +96,16 @@ public class FrameReadWriteTest extends BriarTestCase {
 		assertArrayEquals(tag, recoveredTag);
 		assertEquals(0L, TagEncoder.decodeTag(tag, tagCipher, tagKey));
 		// Read the frames back
-		IncomingEncryptionLayer decrypter = new IncomingEncryptionLayerImpl(in,
-				tagCipher, segCipher, tagKey, segKey, false, recoveredTag);
-		IncomingErrorCorrectionLayer correcter1 =
-			new NullIncomingErrorCorrectionLayer(decrypter);
-		IncomingAuthenticationLayer authenticator =
-			new IncomingAuthenticationLayerImpl(correcter1, mac, macKey);
-		IncomingReliabilityLayer reliability =
-			new NullIncomingReliabilityLayer(authenticator);
-		ConnectionReader reader = new ConnectionReaderImpl(reliability, false);
+		IncomingEncryptionLayer encryptionIn = new IncomingEncryptionLayerImpl(
+				in, tagCipher, segCipher, tagKey, segKey, false, recoveredTag);
+		IncomingErrorCorrectionLayer correctionIn =
+			new NullIncomingErrorCorrectionLayer(encryptionIn);
+		IncomingAuthenticationLayer authenticationIn =
+			new IncomingAuthenticationLayerImpl(correctionIn, mac, macKey);
+		IncomingReliabilityLayer reliabilityIn =
+			new NullIncomingReliabilityLayer(authenticationIn);
+		ConnectionReader reader = new ConnectionReaderImpl(reliabilityIn,
+				false);
 		InputStream in1 = reader.getInputStream();
 		byte[] recovered = new byte[frame.length];
 		int offset = 0;