Pass segments rather than frames to/from segmented plugins.

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

@@ -14,7 +14,6 @@ import javax.crypto.spec.IvParameterSpec;
 
 import net.sf.briar.api.FormatException;
 import net.sf.briar.api.crypto.ErasableKey;
-import net.sf.briar.api.plugins.FrameSource;
 
 class ConnectionDecrypter implements FrameSource {
 
@@ -49,6 +48,8 @@ class ConnectionDecrypter implements FrameSource {
 		} catch(GeneralSecurityException badIvOrKey) {
 			throw new RuntimeException(badIvOrKey);
 		}
+		// Clear the buffer before exposing it to the transport plugin
+		for(int i = 0; i < b.length; i++) b[i] = 0;
 		try {
 			// Read the first block
 			int offset = 0;
@@ -64,7 +65,7 @@ class ConnectionDecrypter implements FrameSource {
 			// Decrypt the first block
 			try {
 				int decrypted = frameCipher.update(b, 0, blockSize, b);
-				assert decrypted == blockSize;
+				if(decrypted != blockSize) throw new RuntimeException();
 			} catch(GeneralSecurityException badCipher) {
 				throw new RuntimeException(badCipher);
 			}
@@ -86,7 +87,8 @@ class ConnectionDecrypter implements FrameSource {
 			try {
 				int decrypted = frameCipher.doFinal(b, blockSize,
 						length - blockSize, b, blockSize);
-				assert decrypted == length - blockSize;
+				if(decrypted != length - blockSize)
+					throw new RuntimeException();
 			} catch(GeneralSecurityException badCipher) {
 				throw new RuntimeException(badCipher);
 			}

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

@@ -2,7 +2,6 @@ package net.sf.briar.transport;
 
 import java.io.IOException;
 
-import net.sf.briar.api.plugins.FrameSink;
 
 /** Encrypts authenticated data to be sent over a connection. */
 interface ConnectionEncrypter extends FrameSink {

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

@@ -50,7 +50,7 @@ class ConnectionEncrypterImpl implements ConnectionEncrypter {
 		try {
 			frameCipher.init(Cipher.ENCRYPT_MODE, frameKey, ivSpec);
 			int encrypted = frameCipher.doFinal(b, 0, len, b);
-			assert encrypted == len;
+			if(encrypted != len) throw new RuntimeException();
 		} catch(GeneralSecurityException badCipher) {
 			throw new RuntimeException(badCipher);
 		}

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

@@ -7,7 +7,6 @@ import javax.crypto.Mac;
 
 import net.sf.briar.api.crypto.CryptoComponent;
 import net.sf.briar.api.crypto.ErasableKey;
-import net.sf.briar.api.plugins.FrameSource;
 import net.sf.briar.api.transport.ConnectionReader;
 import net.sf.briar.api.transport.ConnectionReaderFactory;
 import net.sf.briar.util.ByteUtils;

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

@@ -12,7 +12,6 @@ import javax.crypto.Mac;
 
 import net.sf.briar.api.FormatException;
 import net.sf.briar.api.crypto.ErasableKey;
-import net.sf.briar.api.plugins.FrameSource;
 import net.sf.briar.api.transport.ConnectionReader;
 
 class ConnectionReaderImpl extends InputStream implements ConnectionReader {

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

@@ -0,0 +1,9 @@
+package net.sf.briar.transport;
+
+import java.io.IOException;
+
+interface FrameSink {
+
+	/** Writes the given frame. */
+	void writeFrame(byte[] b, int len) throws IOException;
+}

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

@@ -0,0 +1,12 @@
+package net.sf.briar.transport;
+
+import java.io.IOException;
+
+interface FrameSource {
+
+	/**
+	 * Reads a frame into the given buffer and returns its length, or -1 if no
+	 * more frames can be read.
+	 */
+	int readFrame(byte[] b) throws IOException;
+}

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

@@ -0,0 +1,45 @@
+package net.sf.briar.transport;
+
+import static net.sf.briar.api.transport.TransportConstants.MAX_FRAME_LENGTH;
+import net.sf.briar.api.plugins.Segment;
+import net.sf.briar.util.ByteUtils;
+
+class SegmentImpl implements Segment {
+
+	private final byte[] buf = new byte[MAX_FRAME_LENGTH];
+
+	private int length = -1;
+	private long transmission = -1;
+
+	public void clear() {
+		for(int i = 0; i < buf.length; i++) buf[i] = 0;
+		length = -1;
+		transmission = -1;
+	}
+
+	public byte[] getBuffer() {
+		return buf;
+	}
+
+	public int getLength() {
+		if(length == -1) throw new IllegalStateException();
+		return length;
+	}
+
+	public long getTransmissionNumber() {
+		if(transmission == -1) throw new IllegalStateException();
+		return transmission;
+	}
+
+	public void setLength(int length) {
+		if(length < 0 || length > buf.length)
+			throw new IllegalArgumentException();
+		this.length = length;
+	}
+
+	public void setTransmissionNumber(int transmission) {
+		if(transmission < 0 || transmission > ByteUtils.MAX_32_BIT_UNSIGNED)
+			throw new IllegalArgumentException();
+		this.transmission = transmission;
+	}
+}

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

@@ -12,19 +12,21 @@ import javax.crypto.spec.IvParameterSpec;
 
 import net.sf.briar.api.FormatException;
 import net.sf.briar.api.crypto.ErasableKey;
-import net.sf.briar.api.plugins.FrameSource;
+import net.sf.briar.api.plugins.Segment;
+import net.sf.briar.api.plugins.SegmentSource;
 
 class SegmentedConnectionDecrypter implements FrameSource {
 
-	private final FrameSource in;
+	private final SegmentSource in;
 	private final Cipher frameCipher;
 	private final ErasableKey frameKey;
 	private final int macLength, blockSize;
 	private final byte[] iv;
+	private final Segment segment;
 
 	private long frame = 0L;
 
-	SegmentedConnectionDecrypter(FrameSource in, Cipher frameCipher,
+	SegmentedConnectionDecrypter(SegmentSource in, Cipher frameCipher,
 			ErasableKey frameKey, int macLength) {
 		this.in = in;
 		this.frameCipher = frameCipher;
@@ -34,6 +36,7 @@ class SegmentedConnectionDecrypter implements FrameSource {
 		if(blockSize < FRAME_HEADER_LENGTH)
 			throw new IllegalArgumentException();
 		iv = IvEncoder.encodeIv(0, blockSize);
+		segment = new SegmentImpl();
 	}
 
 	public int readFrame(byte[] b) throws IOException {
@@ -47,17 +50,22 @@ class SegmentedConnectionDecrypter implements FrameSource {
 		} catch(GeneralSecurityException badIvOrKey) {
 			throw new RuntimeException(badIvOrKey);
 		}
+		// Clear the buffer before exposing it to the transport plugin
+		segment.clear();
 		try {
 			// Read the frame
-			int length = in.readFrame(b);
-			if(length == -1) return -1;
+			if(!in.readSegment(segment)) return -1;
+			if(segment.getTransmissionNumber() != frame)
+				throw new FormatException();
+			int length = segment.getLength();
 			if(length > MAX_FRAME_LENGTH) throw new FormatException();
 			if(length < FRAME_HEADER_LENGTH + macLength)
 				throw new FormatException();
 			// Decrypt the frame
 			try {
-				int decrypted = frameCipher.doFinal(b, 0, length, b);
-				assert decrypted == length;
+				int decrypted = frameCipher.doFinal(segment.getBuffer(), 0,
+						length, b);
+				if(decrypted != length) throw new RuntimeException();
 			} catch(GeneralSecurityException badCipher) {
 				throw new RuntimeException(badCipher);
 			}

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

@@ -1,6 +1,7 @@
 package net.sf.briar.transport;
 
 import static net.sf.briar.util.ByteUtils.MAX_32_BIT_UNSIGNED;
+import static net.sf.briar.api.transport.TransportConstants.MAX_FRAME_LENGTH;
 
 import java.io.IOException;
 import java.security.GeneralSecurityException;
@@ -9,20 +10,23 @@ import javax.crypto.Cipher;
 import javax.crypto.spec.IvParameterSpec;
 
 import net.sf.briar.api.crypto.ErasableKey;
-import net.sf.briar.api.plugins.FrameSink;
+import net.sf.briar.api.plugins.Segment;
+import net.sf.briar.api.plugins.SegmentSink;
 
 class SegmentedConnectionEncrypter implements ConnectionEncrypter {
 
-	private final FrameSink out;
+	private final SegmentSink out;
 	private final Cipher frameCipher;
 	private final ErasableKey frameKey;
 	private final byte[] iv, tag;
+	private final Segment segment;
 
 	private long capacity, frame = 0L;
 	private boolean tagWritten = false;
 
-	SegmentedConnectionEncrypter(FrameSink out, long capacity, Cipher tagCipher,
-			Cipher frameCipher, ErasableKey tagKey, ErasableKey frameKey) {
+	SegmentedConnectionEncrypter(SegmentSink out, long capacity,
+			Cipher tagCipher, Cipher frameCipher, ErasableKey tagKey,
+			ErasableKey frameKey) {
 		this.out = out;
 		this.capacity = capacity;
 		this.frameCipher = frameCipher;
@@ -31,16 +35,16 @@ class SegmentedConnectionEncrypter implements ConnectionEncrypter {
 		// Encrypt the tag
 		tag = TagEncoder.encodeTag(0, tagCipher, tagKey);
 		tagKey.erase();
+		segment = new SegmentImpl();
 	}
 
 	public void writeFrame(byte[] b, int len) throws IOException {
 		if(frame > MAX_32_BIT_UNSIGNED) throw new IllegalStateException();
 		int offset = 0;
 		if(!tagWritten) {
-			if(tag.length + len > b.length)
+			if(tag.length + len > MAX_FRAME_LENGTH)
 				throw new IllegalArgumentException();
-			System.arraycopy(b, 0, b, tag.length, len);
-			System.arraycopy(tag, 0, b, 0, tag.length);
+			System.arraycopy(tag, 0, segment.getBuffer(), 0, tag.length);
 			capacity -= tag.length;
 			tagWritten = true;
 			offset = tag.length;
@@ -49,13 +53,15 @@ class SegmentedConnectionEncrypter implements ConnectionEncrypter {
 		IvParameterSpec ivSpec = new IvParameterSpec(iv);
 		try {
 			frameCipher.init(Cipher.ENCRYPT_MODE, frameKey, ivSpec);
-			int encrypted = frameCipher.doFinal(b, offset, len, b, offset);
-			assert encrypted == len;
+			int encrypted = frameCipher.doFinal(b, 0, len, segment.getBuffer(),
+					offset);
+			if(encrypted != len) throw new RuntimeException();
 		} catch(GeneralSecurityException badCipher) {
 			throw new RuntimeException(badCipher);
 		}
+		segment.setLength(offset + len);
 		try {
-			out.writeFrame(b, offset + len);
+			out.writeSegment(segment);
 		} catch(IOException e) {
 			frameKey.erase();
 			throw e;