mirror of
https://code.briarproject.org/briar/briar.git
synced 2026-02-21 07:09:56 +01:00
Removed frame padding code (soon to be obsolete).
This commit is contained in:
akwizgran
@@ -1,44 +0,0 @@
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package net.sf.briar.transport;
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import static net.sf.briar.api.transport.TransportConstants.MAX_FRAME_LENGTH;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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/**
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* A thread that calls the writeFullFrame() method of a PaddedConnectionWriter
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* at regular intervals. The interval between calls is determined by a target
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* output rate. If the underlying output stream cannot accept data at the
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* target rate, calls will be made as frequently as the output stream allows.
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*/
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class FrameScheduler extends Thread {
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private static final Logger LOG =
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Logger.getLogger(FrameScheduler.class.getName());
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private final PaddedConnectionWriter writer;
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private final int millisPerFrame;
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FrameScheduler(PaddedConnectionWriter writer, int bytesPerSecond) {
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this.writer = writer;
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millisPerFrame = bytesPerSecond * 1000 / MAX_FRAME_LENGTH;
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}
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@Override
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public void run() {
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long lastCall = System.currentTimeMillis();
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try {
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while(true) {
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long now = System.currentTimeMillis();
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long nextCall = lastCall + millisPerFrame;
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if(nextCall > now) Thread.sleep(nextCall - now);
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lastCall = System.currentTimeMillis();
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if(!writer.writeFullFrame()) return;
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}
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} catch(InterruptedException e) {
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if(LOG.isLoggable(Level.INFO))
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LOG.info("Interrupted while waiting to write frame");
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Thread.currentThread().interrupt();
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}
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}
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}
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@@ -1,122 +0,0 @@
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package net.sf.briar.transport;
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import static net.sf.briar.util.ByteUtils.MAX_32_BIT_UNSIGNED;
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import java.io.IOException;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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import javax.crypto.Mac;
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import net.sf.briar.api.crypto.ErasableKey;
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import net.sf.briar.util.ByteUtils;
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/**
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* A ConnectionWriter that uses padding to hinder traffic analysis. A full-size
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* frame is written each time the writeFullFrame() method is called, with
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* padding inserted if necessary. Calls to the writer's write() methods will
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* block until there is space to buffer the data.
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*/
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class PaddedConnectionWriter extends ConnectionWriterImpl {
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private static final Logger LOG =
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Logger.getLogger(PaddedConnectionWriter.class.getName());
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private final byte[] padding;
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private boolean closed = false;
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private IOException exception = null;
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PaddedConnectionWriter(ConnectionEncrypter encrypter, Mac mac,
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ErasableKey macKey) {
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super(encrypter, mac, macKey);
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padding = new byte[maxPayloadLength];
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}
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@Override
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public synchronized void close() throws IOException {
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if(exception != null) throw exception;
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if(buf.size() > 0) writeFrame(false);
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out.flush();
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out.close();
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closed = true;
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}
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@Override
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public void flush() throws IOException {
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// Na na na, I can't hear you
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}
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@Override
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public synchronized void write(int b) throws IOException {
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if(exception != null) throw exception;
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if(buf.size() == maxPayloadLength) waitForSpace();
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buf.write(b);
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}
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@Override
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public void write(byte[] b) throws IOException {
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write(b, 0, b.length);
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}
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@Override
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public synchronized void write(byte[] b, int off, int len)
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throws IOException {
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if(exception != null) throw exception;
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int available = maxPayloadLength - buf.size();
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while(available < len) {
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buf.write(b, off, available);
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off += available;
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len -= available;
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waitForSpace();
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available = maxPayloadLength;
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}
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buf.write(b, off, len);
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}
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/**
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* Attempts to write a full-size frame, inserting padding if necessary, and
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* returns true if the frame was written. If this method returns false it
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* should not be called again.
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*/
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synchronized boolean writeFullFrame() {
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if(closed) return false;
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try {
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writeFrame(true);
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notify();
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return true;
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} catch(IOException e) {
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exception = e;
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return false;
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}
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}
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private synchronized void writeFrame(boolean pad) throws IOException {
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if(frame > MAX_32_BIT_UNSIGNED) throw new IllegalStateException();
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byte[] payload = buf.toByteArray();
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if(payload.length > maxPayloadLength) throw new IllegalStateException();
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int paddingLength = pad ? maxPayloadLength - payload.length : 0;
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ByteUtils.writeUint16(payload.length, header, 0);
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ByteUtils.writeUint16(paddingLength, header, 2);
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out.write(header);
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mac.update(header);
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out.write(payload);
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mac.update(payload);
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out.write(padding, 0, paddingLength);
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mac.update(padding, 0, paddingLength);
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encrypter.writeFinal(mac.doFinal());
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frame++;
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buf.reset();
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}
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private synchronized void waitForSpace() throws IOException {
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try {
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wait();
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} catch(InterruptedException e) {
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if(LOG.isLoggable(Level.INFO))
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LOG.info("Interrupted while waiting for space");
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Thread.currentThread().interrupt();
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}
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if(exception != null) throw exception;
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}
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}
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@@ -55,7 +55,6 @@
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<test name='net.sf.briar.transport.ConnectionWriterImplTest'/>
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<test name='net.sf.briar.transport.ConnectionWriterImplTest'/>
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<test name='net.sf.briar.transport.ConnectionWriterTest'/>
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<test name='net.sf.briar.transport.ConnectionWriterTest'/>
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<test name='net.sf.briar.transport.FrameReadWriteTest'/>
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<test name='net.sf.briar.transport.FrameReadWriteTest'/>
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<test name='net.sf.briar.transport.PaddedConnectionWriterTest'/>
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<test name='net.sf.briar.transport.batch.BatchConnectionReadWriteTest'/>
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<test name='net.sf.briar.transport.batch.BatchConnectionReadWriteTest'/>
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<test name='net.sf.briar.util.ByteUtilsTest'/>
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<test name='net.sf.briar.util.ByteUtilsTest'/>
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<test name='net.sf.briar.util.FileUtilsTest'/>
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<test name='net.sf.briar.util.FileUtilsTest'/>
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@@ -1,163 +0,0 @@
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package net.sf.briar.transport;
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import static net.sf.briar.api.transport.TransportConstants.MAX_FRAME_LENGTH;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.util.concurrent.CountDownLatch;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.atomic.AtomicBoolean;
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import net.sf.briar.api.transport.ConnectionWriter;
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import net.sf.briar.util.ByteUtils;
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import org.junit.Test;
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public class PaddedConnectionWriterTest extends TransportTest {
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public PaddedConnectionWriterTest() throws Exception {
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super();
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}
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@Test
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public void testWriteByteDoesNotBlockUntilBufferIsFull() throws Exception {
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ByteArrayOutputStream out = new ByteArrayOutputStream();
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ConnectionEncrypter e = new NullConnectionEncrypter(out, Long.MAX_VALUE);
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ConnectionWriter w = new PaddedConnectionWriter(e, mac, macKey);
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final OutputStream out1 = w.getOutputStream();
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final CountDownLatch latch = new CountDownLatch(1);
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final AtomicBoolean finished = new AtomicBoolean(false);
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final AtomicBoolean failed = new AtomicBoolean(false);
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new Thread() {
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@Override
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public void run() {
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try {
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for(int i = 0; i < maxPayloadLength; i++) out1.write(0);
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finished.set(true);
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} catch(IOException e) {
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failed.set(true);
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}
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latch.countDown();
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}
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}.start();
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// The wait should not time out
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assertTrue(latch.await(1, TimeUnit.SECONDS));
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assertTrue(finished.get());
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assertFalse(failed.get());
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// Nothing should have been written
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assertEquals(0, out.size());
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}
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@Test
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public void testWriteByteBlocksWhenBufferIsFull() throws Exception {
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ByteArrayOutputStream out = new ByteArrayOutputStream();
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ConnectionEncrypter e = new NullConnectionEncrypter(out, Long.MAX_VALUE);
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PaddedConnectionWriter w = new PaddedConnectionWriter(e, mac, macKey);
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final OutputStream out1 = w.getOutputStream();
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final CountDownLatch latch = new CountDownLatch(1);
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final AtomicBoolean finished = new AtomicBoolean(false);
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final AtomicBoolean failed = new AtomicBoolean(false);
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new Thread() {
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@Override
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public void run() {
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try {
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for(int i = 0; i < maxPayloadLength + 1; i++) out1.write(0);
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finished.set(true);
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} catch(IOException e) {
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failed.set(true);
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}
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latch.countDown();
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}
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}.start();
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// The wait should time out
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assertFalse(latch.await(1, TimeUnit.SECONDS));
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assertFalse(finished.get());
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assertFalse(failed.get());
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// Calling writeFullFrame() should allow the writer to proceed
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w.writeFullFrame();
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assertTrue(latch.await(1, TimeUnit.SECONDS));
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assertTrue(finished.get());
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assertFalse(failed.get());
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// A full frame should have been written
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assertEquals(MAX_FRAME_LENGTH, out.size());
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}
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@Test
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public void testWriteArrayDoesNotBlockUntilBufferIsFull() throws Exception {
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ByteArrayOutputStream out = new ByteArrayOutputStream();
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ConnectionEncrypter e = new NullConnectionEncrypter(out, Long.MAX_VALUE);
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ConnectionWriter w = new PaddedConnectionWriter(e, mac, macKey);
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final OutputStream out1 = w.getOutputStream();
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final CountDownLatch latch = new CountDownLatch(1);
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final AtomicBoolean finished = new AtomicBoolean(false);
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final AtomicBoolean failed = new AtomicBoolean(false);
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new Thread() {
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@Override
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public void run() {
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try {
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out1.write(new byte[maxPayloadLength]);
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finished.set(true);
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} catch(IOException e) {
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failed.set(true);
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}
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latch.countDown();
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}
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}.start();
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// The wait should not time out
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assertTrue(latch.await(1, TimeUnit.SECONDS));
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assertTrue(finished.get());
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assertFalse(failed.get());
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// Nothing should have been written
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assertEquals(0, out.size());
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}
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@Test
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public void testWriteArrayBlocksWhenBufferIsFull() throws Exception {
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ByteArrayOutputStream out = new ByteArrayOutputStream();
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ConnectionEncrypter e = new NullConnectionEncrypter(out, Long.MAX_VALUE);
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PaddedConnectionWriter w = new PaddedConnectionWriter(e, mac, macKey);
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final OutputStream out1 = w.getOutputStream();
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final CountDownLatch latch = new CountDownLatch(1);
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final AtomicBoolean finished = new AtomicBoolean(false);
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final AtomicBoolean failed = new AtomicBoolean(false);
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new Thread() {
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@Override
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public void run() {
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try {
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out1.write(new byte[maxPayloadLength + 1]);
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finished.set(true);
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} catch(IOException e) {
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failed.set(true);
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}
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latch.countDown();
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}
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}.start();
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// The wait should time out
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assertFalse(latch.await(1, TimeUnit.SECONDS));
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assertFalse(finished.get());
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assertFalse(failed.get());
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// Calling writeFullFrame() should allow the writer to proceed
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w.writeFullFrame();
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assertTrue(latch.await(1, TimeUnit.SECONDS));
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assertTrue(finished.get());
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assertFalse(failed.get());
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// A full frame should have been written
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assertEquals(MAX_FRAME_LENGTH, out.size());
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}
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@Test
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public void testWriteFullFrameInsertsPadding() throws Exception {
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ByteArrayOutputStream out = new ByteArrayOutputStream();
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ConnectionEncrypter e = new NullConnectionEncrypter(out, Long.MAX_VALUE);
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PaddedConnectionWriter w = new PaddedConnectionWriter(e, mac, macKey);
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w.getOutputStream().write(0);
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w.writeFullFrame();
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// A full frame should have been written
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assertEquals(MAX_FRAME_LENGTH, out.size());
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// The frame should have a payload length of 1 and padding for the rest
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byte[] frame = out.toByteArray();
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assertEquals(1, ByteUtils.readUint16(frame, 0)); // Payload length
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assertEquals(maxPayloadLength - 1, ByteUtils.readUint16(frame, 2));
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}
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}
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Reference in New Issue
Block a user