diff --git a/api/net/sf/briar/api/transport/TransportConstants.java b/api/net/sf/briar/api/transport/TransportConstants.java
index b8158078bd597ed2eae8c7217fe93ac361ec5224..5e65a43c1d93eb03763b6adbc11461023e1c855d 100644
--- a/api/net/sf/briar/api/transport/TransportConstants.java
+++ b/api/net/sf/briar/api/transport/TransportConstants.java
@@ -26,4 +26,7 @@ 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;
}
diff --git a/components/net/sf/briar/transport/ConnectionWindowImpl.java b/components/net/sf/briar/transport/ConnectionWindowImpl.java
index 09faa909aa986a0cbc197e3fe9fb7dee56527c4d..d20eca411de139ec13e7a44e25e29101c86ee498 100644
--- a/components/net/sf/briar/transport/ConnectionWindowImpl.java
+++ b/components/net/sf/briar/transport/ConnectionWindowImpl.java
@@ -83,12 +83,12 @@ class ConnectionWindowImpl implements ConnectionWindow {
}
// Returns the lowest value contained in a window with the given centre
- private long getBottom(long centre) {
+ private static long getBottom(long centre) {
return Math.max(0, centre - CONNECTION_WINDOW_SIZE / 2);
}
// Returns the highest value contained in a window with the given centre
- private long getTop(long centre) {
+ private static long getTop(long centre) {
return Math.min(ByteUtils.MAX_32_BIT_UNSIGNED,
centre + CONNECTION_WINDOW_SIZE / 2 - 1);
}
diff --git a/components/net/sf/briar/transport/FrameWindow.java b/components/net/sf/briar/transport/FrameWindow.java
new file mode 100644
index 0000000000000000000000000000000000000000..dcb1d75a9e81b78df78113940e8ab8c61355b2aa
--- /dev/null
+++ b/components/net/sf/briar/transport/FrameWindow.java
@@ -0,0 +1,22 @@
+package net.sf.briar.transport;
+
+interface FrameWindow {
+
+ /** Returns true if the given number is in the window. */
+ boolean contains(long frameNumber);
+
+ /**
+ * Advances the window so it is centred on the given number, unless the
+ * centre is already greater than the number. Returns false if the window
+ * is unmodifiable.
+ */
+ boolean advance(long frameNumber);
+
+ /**
+ * Removes the given number from the window and, if the number is greater
+ * than or equal to the window's centre, advances the centre to one greater
+ * than the given number. Returns false if the given number is not in the
+ * window or the window is unmodifiable.
+ */
+ boolean remove(long frameNumber);
+}
diff --git a/components/net/sf/briar/transport/FrameWindowImpl.java b/components/net/sf/briar/transport/FrameWindowImpl.java
new file mode 100644
index 0000000000000000000000000000000000000000..3348ce73f4fe18a16d86fb9ab3922638b1f16fb8
--- /dev/null
+++ b/components/net/sf/briar/transport/FrameWindowImpl.java
@@ -0,0 +1,63 @@
+package net.sf.briar.transport;
+
+import static net.sf.briar.api.transport.TransportConstants.FRAME_WINDOW_SIZE;
+import static net.sf.briar.util.ByteUtils.MAX_32_BIT_UNSIGNED;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Iterator;
+
+class FrameWindowImpl implements FrameWindow {
+
+ private final Collection<Long> window;
+
+ private long centre;
+
+ FrameWindowImpl() {
+ window = new HashSet<Long>();
+ for(long l = 0; l < FRAME_WINDOW_SIZE / 2; l++) window.add(l);
+ centre = 0;
+ }
+
+ public boolean contains(long frameNumber) {
+ if(frameNumber < 0 || frameNumber > MAX_32_BIT_UNSIGNED)
+ throw new IllegalArgumentException();
+ return window.contains(frameNumber);
+ }
+
+ public boolean advance(long frameNumber) {
+ if(frameNumber < 0 || frameNumber > MAX_32_BIT_UNSIGNED)
+ throw new IllegalArgumentException();
+ if(frameNumber <= centre) return true;
+ // Remove values that have passed out of the window
+ long newBottom = getBottom(frameNumber);
+ Iterator<Long> it = window.iterator();
+ while(it.hasNext()) if(it.next() < newBottom) it.remove();
+ // Add values that have passed into the window
+ long fillFrom = Math.max(newBottom, getTop(centre) + 1);
+ long newTop = getTop(frameNumber);
+ for(long l = fillFrom; l <= newTop; l++) window.add(l);
+ centre = frameNumber;
+ return true;
+ }
+
+ public boolean remove(long frameNumber) {
+ if(frameNumber < 0 || frameNumber > MAX_32_BIT_UNSIGNED)
+ throw new IllegalArgumentException();
+ if(!window.remove(frameNumber)) return false;
+ if(frameNumber >= centre && frameNumber < MAX_32_BIT_UNSIGNED)
+ advance(frameNumber + 1);
+ return true;
+ }
+
+ // Returns the lowest value contained in a window with the given centre
+ private static long getBottom(long centre) {
+ return Math.max(0, centre - FRAME_WINDOW_SIZE / 2);
+ }
+
+ // Returns the highest value contained in a window with the given centre
+ private static long getTop(long centre) {
+ return Math.min(MAX_32_BIT_UNSIGNED,
+ centre + FRAME_WINDOW_SIZE / 2 - 1);
+ }
+}
diff --git a/components/net/sf/briar/transport/HeaderEncoder.java b/components/net/sf/briar/transport/HeaderEncoder.java
index b1d47a6c1b5bed306dc2b8db82751b02ba80d76b..18b3aecef2546883fcf1d719c663701bd09dac0d 100644
--- a/components/net/sf/briar/transport/HeaderEncoder.java
+++ b/components/net/sf/briar/transport/HeaderEncoder.java
@@ -22,9 +22,8 @@ class HeaderEncoder {
ByteUtils.writeUint16(padding, header, 6);
}
- static boolean validateHeader(byte[] header, long frameNumber) {
+ static boolean validateHeader(byte[] header) {
if(header.length < FRAME_HEADER_LENGTH) return false;
- if(ByteUtils.readUint32(header, 0) != frameNumber) return false;
int payload = ByteUtils.readUint16(header, 4);
int padding = ByteUtils.readUint16(header, 6);
int frameLength = FRAME_HEADER_LENGTH + payload + padding + MAC_LENGTH;
diff --git a/components/net/sf/briar/transport/IncomingAuthenticationLayer.java b/components/net/sf/briar/transport/IncomingAuthenticationLayer.java
index c9559537fb9ef780be1e5e937898c643bb37f369..22dd0df36510f5961c3cbc5012b66c5d204eabb1 100644
--- a/components/net/sf/briar/transport/IncomingAuthenticationLayer.java
+++ b/components/net/sf/briar/transport/IncomingAuthenticationLayer.java
@@ -1,7 +1,6 @@
package net.sf.briar.transport;
import java.io.IOException;
-import java.util.Collection;
interface IncomingAuthenticationLayer {
@@ -14,6 +13,6 @@ interface IncomingAuthenticationLayer {
* @throws InvalidDataException if a recoverable error occurs. The caller
* may choose whether to retry the read or close the connection.
*/
- boolean readFrame(Frame f, Collection<Long> window) throws IOException,
+ boolean readFrame(Frame f, FrameWindow window) throws IOException,
InvalidDataException;
}
diff --git a/components/net/sf/briar/transport/IncomingAuthenticationLayerImpl.java b/components/net/sf/briar/transport/IncomingAuthenticationLayerImpl.java
index 14320757c345e9c09ada122b0dc3d125604cd6f4..4c33c29e155d0ae961ce0c8737ee3d1944a4c5e9 100644
--- a/components/net/sf/briar/transport/IncomingAuthenticationLayerImpl.java
+++ b/components/net/sf/briar/transport/IncomingAuthenticationLayerImpl.java
@@ -5,7 +5,6 @@ import static net.sf.briar.api.transport.TransportConstants.MAC_LENGTH;
import java.io.IOException;
import java.security.InvalidKeyException;
-import java.util.Collection;
import javax.crypto.Mac;
@@ -31,15 +30,13 @@ class IncomingAuthenticationLayerImpl implements IncomingAuthenticationLayer {
throw new IllegalArgumentException();
}
- public boolean readFrame(Frame f, Collection<Long> window)
- throws IOException, InvalidDataException {
+ public boolean readFrame(Frame f, FrameWindow window) throws IOException,
+ InvalidDataException {
// Read a frame
if(!in.readFrame(f, window)) return false;
// Check that the length is legal
byte[] buf = f.getBuffer();
- long frameNumber = HeaderEncoder.getFrameNumber(buf);
- if(!HeaderEncoder.validateHeader(buf, frameNumber))
- throw new InvalidDataException();
+ if(!HeaderEncoder.validateHeader(buf)) throw new InvalidDataException();
// Check that the payload and padding lengths are correct
int payload = HeaderEncoder.getPayloadLength(buf);
int padding = HeaderEncoder.getPaddingLength(buf);
@@ -58,7 +55,6 @@ class IncomingAuthenticationLayerImpl implements IncomingAuthenticationLayer {
if(expectedMac[i] != buf[macStart + i])
throw new InvalidDataException();
}
- frameNumber++;
return true;
}
}
diff --git a/components/net/sf/briar/transport/IncomingErrorCorrectionLayer.java b/components/net/sf/briar/transport/IncomingErrorCorrectionLayer.java
index bd555c150cd66c33757e20d1bccf91ff4cd8adfc..e49e0cbb9fe5ca344c29459695ec31f8e66cd521 100644
--- a/components/net/sf/briar/transport/IncomingErrorCorrectionLayer.java
+++ b/components/net/sf/briar/transport/IncomingErrorCorrectionLayer.java
@@ -1,7 +1,6 @@
package net.sf.briar.transport;
import java.io.IOException;
-import java.util.Collection;
interface IncomingErrorCorrectionLayer {
@@ -14,6 +13,6 @@ interface IncomingErrorCorrectionLayer {
* @throws InvalidDataException if a recoverable error occurs. The caller
* may choose whether to retry the read or close the connection.
*/
- boolean readFrame(Frame f, Collection<Long> window) throws IOException,
+ boolean readFrame(Frame f, FrameWindow window) throws IOException,
InvalidDataException;
}
diff --git a/components/net/sf/briar/transport/NullFrameWindow.java b/components/net/sf/briar/transport/NullFrameWindow.java
new file mode 100644
index 0000000000000000000000000000000000000000..c8560de86161b2ecca76a325d2b00255d6bff3c0
--- /dev/null
+++ b/components/net/sf/briar/transport/NullFrameWindow.java
@@ -0,0 +1,20 @@
+package net.sf.briar.transport;
+
+class NullFrameWindow implements FrameWindow {
+
+ private long centre = 0L;
+
+ public boolean contains(long frameNumber) {
+ return frameNumber == centre;
+ }
+
+ public boolean advance(long frameNumber) {
+ return frameNumber == centre;
+ }
+
+ public boolean remove(long frameNumber) {
+ if(frameNumber != centre) return false;
+ centre++;
+ return true;
+ }
+}
diff --git a/components/net/sf/briar/transport/NullIncomingErrorCorrectionLayer.java b/components/net/sf/briar/transport/NullIncomingErrorCorrectionLayer.java
index 7d344a592909cbe11cffa291a00edcb71e1386de..87ce8d4b358ee0bb4d2dc76b248fc8a4d9e37c69 100644
--- a/components/net/sf/briar/transport/NullIncomingErrorCorrectionLayer.java
+++ b/components/net/sf/briar/transport/NullIncomingErrorCorrectionLayer.java
@@ -1,7 +1,6 @@
package net.sf.briar.transport;
import java.io.IOException;
-import java.util.Collection;
import net.sf.briar.api.transport.Segment;
@@ -15,7 +14,7 @@ class NullIncomingErrorCorrectionLayer implements IncomingErrorCorrectionLayer {
segment = new SegmentImpl();
}
- public boolean readFrame(Frame f, Collection<Long> window)
+ public boolean readFrame(Frame f, FrameWindow window)
throws IOException, InvalidDataException {
while(true) {
if(!in.readSegment(segment)) return false;
diff --git a/components/net/sf/briar/transport/NullIncomingReliabilityLayer.java b/components/net/sf/briar/transport/NullIncomingReliabilityLayer.java
index b8b965fc17bac7a238239337b3cbcb8e1141ef66..3ecd84502c6bd9081f2767c1bfa7a774144903b5 100644
--- a/components/net/sf/briar/transport/NullIncomingReliabilityLayer.java
+++ b/components/net/sf/briar/transport/NullIncomingReliabilityLayer.java
@@ -1,24 +1,22 @@
package net.sf.briar.transport;
import java.io.IOException;
-import java.util.Collection;
-import java.util.Collections;
class NullIncomingReliabilityLayer implements IncomingReliabilityLayer {
private final IncomingAuthenticationLayer in;
-
- private long frameNumber = 0L;
+ private final FrameWindow window;
NullIncomingReliabilityLayer(IncomingAuthenticationLayer in) {
this.in = in;
+ window = new NullFrameWindow();
}
public boolean readFrame(Frame f) throws IOException, InvalidDataException {
- // Frames must be read in order
- Collection<Long> window = Collections.singleton(frameNumber);
if(!in.readFrame(f, window)) return false;
- frameNumber++;
+ long frameNumber = HeaderEncoder.getFrameNumber(f.getBuffer());
+ if(!window.remove(frameNumber) && window.advance(frameNumber))
+ throw new RuntimeException();
return true;
}
}
diff --git a/test/build.xml b/test/build.xml
index a92959b5055890ff9efb1a7f154ce7561edbd5e2..3998eadb1f6db632eed0e39e80c54f451b3184ab 100644
--- a/test/build.xml
+++ b/test/build.xml
@@ -56,6 +56,7 @@
<test name='net.sf.briar.transport.ConnectionWriterImplTest'/>
<test name='net.sf.briar.transport.ConnectionWriterTest'/>
<test name='net.sf.briar.transport.FrameReadWriteTest'/>
+ <test name='net.sf.briar.transport.FrameWindowImplTest'/>
<test name='net.sf.briar.transport.IncomingEncryptionLayerImplTest'/>
<test name='net.sf.briar.transport.IncomingSegmentedEncryptionLayerTest'/>
<test name='net.sf.briar.transport.OutgoingEncryptionLayerImplTest'/>
diff --git a/test/net/sf/briar/transport/FrameWindowImplTest.java b/test/net/sf/briar/transport/FrameWindowImplTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..1cc08245701af5501d48d0df6d78d4db22cb7df9
--- /dev/null
+++ b/test/net/sf/briar/transport/FrameWindowImplTest.java
@@ -0,0 +1,89 @@
+package net.sf.briar.transport;
+
+import net.sf.briar.BriarTestCase;
+import static net.sf.briar.api.transport.TransportConstants.FRAME_WINDOW_SIZE;
+import static net.sf.briar.util.ByteUtils.MAX_32_BIT_UNSIGNED;
+
+import org.junit.Test;
+
+public class FrameWindowImplTest extends BriarTestCase {
+
+ @Test
+ public void testWindowSliding() {
+ FrameWindow w = new FrameWindowImpl();
+ for(int i = 0; i < 100; i++) {
+ assertTrue(w.contains(i));
+ w.remove(i);
+ assertFalse(w.contains(i));
+ }
+ }
+
+ @Test
+ public void testWindowJumping() {
+ FrameWindow w = new FrameWindowImpl();
+ for(int i = 0; i < 100; i += 13) {
+ assertTrue(w.contains(i));
+ w.remove(i);
+ assertFalse(w.contains(i));
+ }
+ }
+
+ @Test
+ public void testWindowUpperLimit() {
+ FrameWindow w = new FrameWindowImpl();
+ // Centre is 0, highest value in window is 15
+ for(int i = 0; i < 16; i++) assertTrue(w.contains(i));
+ assertFalse(w.remove(16));
+ assertTrue(w.remove(15));
+ assertFalse(w.remove(15));
+ // Centre is 16, highest value in window is 31
+ for(int i = 0; i < 32; i++) assertEquals(i != 15, w.contains(i));
+ assertFalse(w.remove(32));
+ assertTrue(w.remove(31));
+ // Values greater than 2^32 - 1 should never be allowed
+ assertTrue(w.advance(MAX_32_BIT_UNSIGNED - 1));
+ assertTrue(w.remove(MAX_32_BIT_UNSIGNED - 1));
+ assertTrue(w.remove(MAX_32_BIT_UNSIGNED));
+ try {
+ w.remove(MAX_32_BIT_UNSIGNED + 1);
+ fail();
+ } catch(IllegalArgumentException expected) {}
+ }
+
+ @Test
+ public void testAdvance() {
+ FrameWindow w = new FrameWindowImpl();
+ long centre = 0;
+ for(int i = 0; i < 10; i++) {
+ long bottom = Math.max(0, centre - FRAME_WINDOW_SIZE / 2);
+ long top = Math.min(MAX_32_BIT_UNSIGNED,
+ centre + FRAME_WINDOW_SIZE / 2 - 1);
+ if(bottom > 0) assertFalse(w.contains(bottom - 1));
+ for(long j = bottom; j <= top; j++) assertTrue(w.contains(j));
+ if(top < MAX_32_BIT_UNSIGNED) assertFalse(w.contains(top + 1));
+ centre += 12345;
+ assertTrue(w.advance(centre));
+ }
+ }
+
+ @Test
+ public void testWindowLowerLimit() {
+ FrameWindow w = new FrameWindowImpl();
+ // Centre is 0, negative values should never be allowed
+ try {
+ w.remove(-1);
+ fail();
+ } catch(IllegalArgumentException expected) {}
+ // Slide the window twice
+ assertTrue(w.remove(15));
+ assertTrue(w.remove(16));
+ // Centre is 17, lowest value in window is 1
+ assertFalse(w.remove(0));
+ assertTrue(w.remove(1));
+ // Slide the window
+ assertTrue(w.remove(25));
+ // Centre is 26, lowest value in window is 10
+ assertFalse(w.remove(9));
+ assertTrue(w.remove(10));
+ }
+}
\ No newline at end of file