Unit tests for ConnectionReaderImpl.

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

 package net.sf.briar.transport;
 
+import static net.sf.briar.api.transport.TransportConstants.MAX_FRAME_LENGTH;
+
 import java.io.ByteArrayInputStream;
 import java.io.EOFException;
 import java.io.IOException;
@@ -10,6 +12,7 @@ import javax.crypto.Mac;
 
 import junit.framework.TestCase;
 import net.sf.briar.TestUtils;
+import net.sf.briar.api.FormatException;
 import net.sf.briar.api.crypto.CryptoComponent;
 import net.sf.briar.api.transport.ConnectionReader;
 import net.sf.briar.crypto.CryptoModule;
@@ -33,13 +36,28 @@ public class ConnectionReaderImplTest extends TestCase {
 		mac.init(crypto.generateSecretKey());
 	}
 
-	// FIXME: Test corner cases and corrupt frames
+	@Test
+	public void testLengthZero() throws Exception {
+		// Six bytes for the header, none for the payload
+		byte[] frame = new byte[6 + mac.getMacLength()];
+		// Calculate the MAC
+		mac.update(frame, 0, 6);
+		mac.doFinal(frame, 6);
+		// Read the frame
+		ByteArrayInputStream in = new ByteArrayInputStream(frame);
+		ConnectionDecrypter d = new NullConnectionDecrypter(in);
+		ConnectionReader r = new ConnectionReaderImpl(d, mac);
+		try {
+			r.getInputStream().read();
+			fail();
+		} catch(FormatException expected) {}
+	}
 
 	@Test
-	public void testSingleByteFrame() throws Exception {
+	public void testLengthOne() throws Exception {
 		// Six bytes for the header, one for the payload
 		byte[] frame = new byte[6 + 1 + mac.getMacLength()];
-		ByteUtils.writeUint16(1, frame, 4); // Payload length = 1
+		ByteUtils.writeUint16(1, frame, 4); // Frame number 0, length 1
 		// Calculate the MAC
 		mac.update(frame, 0, 6 + 1);
 		mac.doFinal(frame, 6 + 1);
@@ -52,17 +70,49 @@ public class ConnectionReaderImplTest extends TestCase {
 		assertEquals(-1, r.getInputStream().read());
 	}
 
+	@Test
+	public void testMaxLength() throws Exception {
+		int maxPayloadLength = MAX_FRAME_LENGTH - 6 - mac.getMacLength();
+		// First frame: max payload length
+		byte[] frame = new byte[6 + maxPayloadLength + mac.getMacLength()];
+		ByteUtils.writeUint16(maxPayloadLength, frame, 4);
+		mac.update(frame, 0, 6 + maxPayloadLength);
+		mac.doFinal(frame, 6 + maxPayloadLength);
+		// Second frame: max payload length plus one
+		byte[] frame1 = new byte[6 + maxPayloadLength + 1 + mac.getMacLength()];
+		ByteUtils.writeUint32(1, frame1, 0);
+		ByteUtils.writeUint16(maxPayloadLength + 1, frame1, 4);
+		mac.update(frame1, 0, 6 + maxPayloadLength + 1);
+		mac.doFinal(frame1, 6 + maxPayloadLength + 1);
+		// Concatenate the frames
+		ByteArrayOutputStream out = new ByteArrayOutputStream();
+		out.write(frame);
+		out.write(frame1);
+		// Read the first frame
+		ByteArrayInputStream in = new ByteArrayInputStream(out.toByteArray());
+		ConnectionDecrypter d = new NullConnectionDecrypter(in);
+		ConnectionReader r = new ConnectionReaderImpl(d, mac);
+		byte[] read = new byte[maxPayloadLength];
+		TestUtils.readFully(r.getInputStream(), read);
+		// Try to read the second frame
+		byte[] read1 = new byte[maxPayloadLength + 1];
+		try {
+			TestUtils.readFully(r.getInputStream(), read1);
+			fail();
+		} catch(FormatException expected) {}
+	}
+
 	@Test
 	public void testMultipleFrames() throws Exception {
 		// First frame: 123-byte payload
 		byte[] frame = new byte[6 + 123 + mac.getMacLength()];
-		ByteUtils.writeUint16(123, frame, 4);
+		ByteUtils.writeUint16(123, frame, 4); // Frame number 0, length 123
 		mac.update(frame, 0, 6 + 123);
 		mac.doFinal(frame, 6 + 123);
 		// Second frame: 1234-byte payload
 		byte[] frame1 = new byte[6 + 1234 + mac.getMacLength()];
-		ByteUtils.writeUint32(1, frame1, 0);
-		ByteUtils.writeUint16(1234, frame1, 4);
+		ByteUtils.writeUint32(1, frame1, 0); // Frame number 1
+		ByteUtils.writeUint16(1234, frame1, 4); // Length 1234
 		mac.update(frame1, 0, 6 + 1234);
 		mac.doFinal(frame1, 6 + 1234);
 		// Concatenate the frames
@@ -81,6 +131,46 @@ public class ConnectionReaderImplTest extends TestCase {
 		assertTrue(Arrays.equals(new byte[1234], read1));
 	}
 
+	@Test
+	public void testCorruptPayload() throws Exception {
+		// Six bytes for the header, eight for the payload
+		byte[] frame = new byte[6 + 8 + mac.getMacLength()];
+		ByteUtils.writeUint16(8, frame, 4); // Frame number 0, length 8
+		// Calculate the MAC
+		mac.update(frame, 0, 6 + 8);
+		mac.doFinal(frame, 6 + 8);
+		// Modify the payload
+		frame[12] ^= 1;
+		// Try to read the frame - not a single byte should be read
+		ByteArrayInputStream in = new ByteArrayInputStream(frame);
+		ConnectionDecrypter d = new NullConnectionDecrypter(in);
+		ConnectionReader r = new ConnectionReaderImpl(d, mac);
+		try {
+			r.getInputStream().read();
+			fail();
+		} catch(FormatException expected) {}
+	}
+
+	@Test
+	public void testCorruptMac() throws Exception {
+		// Six bytes for the header, eight for the payload
+		byte[] frame = new byte[6 + 8 + mac.getMacLength()];
+		ByteUtils.writeUint16(8, frame, 4); // Frame number 0, length 8
+		// Calculate the MAC
+		mac.update(frame, 0, 6 + 8);
+		mac.doFinal(frame, 6 + 8);
+		// Modify the MAC
+		frame[17] ^= 1;
+		// Try to read the frame - not a single byte should be read
+		ByteArrayInputStream in = new ByteArrayInputStream(frame);
+		ConnectionDecrypter d = new NullConnectionDecrypter(in);
+		ConnectionReader r = new ConnectionReaderImpl(d, mac);
+		try {
+			r.getInputStream().read();
+			fail();
+		} catch(FormatException expected) {}
+	}
+
 	/** A ConnectionDecrypter that performs no decryption. */
 	private static class NullConnectionDecrypter
 	implements ConnectionDecrypter {