Show different error message if QR code is too new.

bramble-api/src/main/java/org/briarproject/bramble/api/UnsupportedVersionException.java

-package org.briarproject.bramble.api;
-
-import java.io.IOException;
-
-/**
- * An exception that indicates an unrecoverable version mismatch.
- */
-public class UnsupportedVersionException extends IOException {
-}

bramble-api/src/main/java/org/briarproject/bramble/api/keyagreement/KeyAgreementConstants.java

@@ -3,7 +3,13 @@ package org.briarproject.bramble.api.keyagreement;
 public interface KeyAgreementConstants {
 
 	/**
-	 * The current version of the BQP protocol. Version number 89 is reserved.
+	 * The version of the BQP protocol used in beta releases. This version
+	 * number is reserved.
+	 */
+	byte BETA_PROTOCOL_VERSION = 89;
+
+	/**
+	 * The current version of the BQP protocol.
 	 */
 	byte PROTOCOL_VERSION = 4;
 

bramble-api/src/main/java/org/briarproject/bramble/api/keyagreement/UnsupportedVersionException.java

+package org.briarproject.bramble.api.keyagreement;
+
+import java.io.IOException;
+
+/**
+ * Thrown when a QR code that has been scanned uses a protocol version that is
+ * not supported.
+ */
+public class UnsupportedVersionException extends IOException {
+
+	private final boolean tooOld;
+
+	public UnsupportedVersionException(boolean tooOld) {
+		this.tooOld = tooOld;
+	}
+
+	public boolean isTooOld() {
+		return tooOld;
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/PayloadParserImpl.java

 package org.briarproject.bramble.keyagreement;
 
 import org.briarproject.bramble.api.FormatException;
-import org.briarproject.bramble.api.UnsupportedVersionException;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.data.BdfReader;
 import org.briarproject.bramble.api.data.BdfReaderFactory;
 import org.briarproject.bramble.api.keyagreement.Payload;
 import org.briarproject.bramble.api.keyagreement.PayloadParser;
 import org.briarproject.bramble.api.keyagreement.TransportDescriptor;
+import org.briarproject.bramble.api.keyagreement.UnsupportedVersionException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.BluetoothConstants;
 import org.briarproject.bramble.api.plugin.LanTcpConstants;
@@ -21,6 +21,7 @@ import java.util.List;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
+import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.BETA_PROTOCOL_VERSION;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.COMMIT_LENGTH;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.PROTOCOL_VERSION;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.TRANSPORT_ID_BLUETOOTH;
@@ -43,8 +44,11 @@ class PayloadParserImpl implements PayloadParser {
 		// First byte: the protocol version
 		int protocolVersion = in.read();
 		if (protocolVersion == -1) throw new FormatException();
-		if (protocolVersion != PROTOCOL_VERSION)
-			throw new UnsupportedVersionException();
+		if (protocolVersion != PROTOCOL_VERSION) {
+			boolean tooOld = protocolVersion < PROTOCOL_VERSION ||
+					protocolVersion == BETA_PROTOCOL_VERSION;
+			throw new UnsupportedVersionException(tooOld);
+		}
 		// The rest of the payload is a BDF list with one or more elements
 		BdfReader r = bdfReaderFactory.createReader(in);
 		BdfList payload = r.readList();

bramble-core/src/test/java/org/briarproject/bramble/keyagreement/PayloadParserImplTest.java

+package org.briarproject.bramble.keyagreement;
+
+import org.briarproject.bramble.api.Bytes;
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.data.BdfList;
+import org.briarproject.bramble.api.data.BdfReader;
+import org.briarproject.bramble.api.data.BdfReaderFactory;
+import org.briarproject.bramble.api.keyagreement.Payload;
+import org.briarproject.bramble.api.keyagreement.UnsupportedVersionException;
+import org.briarproject.bramble.test.BrambleMockTestCase;
+import org.jmock.Expectations;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+
+import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.BETA_PROTOCOL_VERSION;
+import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.COMMIT_LENGTH;
+import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.PROTOCOL_VERSION;
+import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+public class PayloadParserImplTest extends BrambleMockTestCase {
+
+	private final BdfReaderFactory bdfReaderFactory =
+			context.mock(BdfReaderFactory.class);
+	private final BdfReader bdfReader = context.mock(BdfReader.class);
+
+	private final PayloadParserImpl payloadParser =
+			new PayloadParserImpl(bdfReaderFactory);
+
+	@Test(expected = FormatException.class)
+	public void testThrowsFormatExceptionIfPayloadIsEmpty() throws Exception {
+		payloadParser.parse(new byte[0]);
+	}
+
+	@Test
+	public void testThrowsUnsupportedVersionExceptionForOldVersion()
+			throws Exception {
+		try {
+			payloadParser.parse(new byte[] {PROTOCOL_VERSION - 1});
+			fail();
+		} catch (UnsupportedVersionException e) {
+			assertTrue(e.isTooOld());
+		}
+	}
+
+	@Test
+	public void testThrowsUnsupportedVersionExceptionForBetaVersion()
+			throws Exception {
+		try {
+			payloadParser.parse(new byte[] {BETA_PROTOCOL_VERSION});
+			fail();
+		} catch (UnsupportedVersionException e) {
+			assertTrue(e.isTooOld());
+		}
+	}
+
+	@Test
+	public void testThrowsUnsupportedVersionExceptionForNewVersion()
+			throws Exception {
+		try {
+			payloadParser.parse(new byte[] {PROTOCOL_VERSION + 1});
+			fail();
+		} catch (UnsupportedVersionException e) {
+			assertFalse(e.isTooOld());
+		}
+	}
+
+	@Test(expected = FormatException.class)
+	public void testThrowsFormatExceptionForEmptyList() throws Exception {
+		context.checking(new Expectations() {{
+			oneOf(bdfReaderFactory).createReader(
+					with(any(ByteArrayInputStream.class)));
+			will(returnValue(bdfReader));
+			oneOf(bdfReader).readList();
+			will(returnValue(new BdfList()));
+		}});
+
+		payloadParser.parse(new byte[] {PROTOCOL_VERSION});
+	}
+
+	@Test(expected = FormatException.class)
+	public void testThrowsFormatExceptionForDataAfterList()
+			throws Exception {
+		byte[] commitment = getRandomBytes(COMMIT_LENGTH);
+
+		context.checking(new Expectations() {{
+			oneOf(bdfReaderFactory).createReader(
+					with(any(ByteArrayInputStream.class)));
+			will(returnValue(bdfReader));
+			oneOf(bdfReader).readList();
+			will(returnValue(BdfList.of(new Bytes(commitment))));
+			oneOf(bdfReader).eof();
+			will(returnValue(false));
+		}});
+
+		payloadParser.parse(new byte[] {PROTOCOL_VERSION});
+	}
+
+	@Test(expected = FormatException.class)
+	public void testThrowsFormatExceptionForShortCommitment()
+			throws Exception {
+		byte[] commitment = getRandomBytes(COMMIT_LENGTH - 1);
+
+		context.checking(new Expectations() {{
+			oneOf(bdfReaderFactory).createReader(
+					with(any(ByteArrayInputStream.class)));
+			will(returnValue(bdfReader));
+			oneOf(bdfReader).readList();
+			will(returnValue(BdfList.of(new Bytes(commitment))));
+			oneOf(bdfReader).eof();
+			will(returnValue(true));
+		}});
+
+		payloadParser.parse(new byte[] {PROTOCOL_VERSION});
+	}
+
+	@Test(expected = FormatException.class)
+	public void testThrowsFormatExceptionForLongCommitment()
+			throws Exception {
+		byte[] commitment = getRandomBytes(COMMIT_LENGTH + 1);
+
+		context.checking(new Expectations() {{
+			oneOf(bdfReaderFactory).createReader(
+					with(any(ByteArrayInputStream.class)));
+			will(returnValue(bdfReader));
+			oneOf(bdfReader).readList();
+			will(returnValue(BdfList.of(new Bytes(commitment))));
+			oneOf(bdfReader).eof();
+			will(returnValue(true));
+		}});
+
+		payloadParser.parse(new byte[] {PROTOCOL_VERSION});
+	}
+
+	@Test
+	public void testAcceptsPayloadWithNoDescriptors() throws Exception {
+		byte[] commitment = getRandomBytes(COMMIT_LENGTH);
+		context.checking(new Expectations() {{
+			oneOf(bdfReaderFactory).createReader(
+					with(any(ByteArrayInputStream.class)));
+			will(returnValue(bdfReader));
+			oneOf(bdfReader).readList();
+			will(returnValue(BdfList.of(new Bytes(commitment))));
+			oneOf(bdfReader).eof();
+			will(returnValue(true));
+		}});
+
+		Payload p = payloadParser.parse(new byte[] {PROTOCOL_VERSION});
+		assertArrayEquals(commitment, p.getCommitment());
+		assertTrue(p.getTransportDescriptors().isEmpty());
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/KeyAgreementFragment.java

@@ -15,7 +15,6 @@ import android.widget.Toast;
 
 import com.google.zxing.Result;
 
-import org.briarproject.bramble.api.UnsupportedVersionException;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementResult;
@@ -23,6 +22,7 @@ import org.briarproject.bramble.api.keyagreement.KeyAgreementTask;
 import org.briarproject.bramble.api.keyagreement.Payload;
 import org.briarproject.bramble.api.keyagreement.PayloadEncoder;
 import org.briarproject.bramble.api.keyagreement.PayloadParser;
+import org.briarproject.bramble.api.keyagreement.UnsupportedVersionException;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementAbortedEvent;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementFailedEvent;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementFinishedEvent;
@@ -244,8 +244,14 @@ public class KeyAgreementFragment extends BaseEventFragment
 			task.connectAndRunProtocol(remotePayload);
 		} catch (UnsupportedVersionException e) {
 			reset();
-			String msg = getString(R.string.qr_code_unsupported,
-					getString(R.string.app_name));
+			String msg;
+			if (e.isTooOld()) {
+				msg = getString(R.string.qr_code_too_old,
+						getString(R.string.app_name));
+			} else {
+				msg = getString(R.string.qr_code_too_new,
+						getString(R.string.app_name));
+			}
 			showNextFragment(ContactExchangeErrorFragment.newInstance(msg));
 		} catch (CameraException e) {
 			logCameraExceptionAndFinish(e);

briar-android/src/main/res/values/strings.xml

@@ -141,7 +141,8 @@
 	<string name="contact_added_toast">Contact added: %s</string>
 	<string name="contact_already_exists">Contact %s already exists</string>
 	<string name="qr_code_invalid">The QR code is invalid</string>
-	<string name="qr_code_unsupported">The QR code you are trying to scan belongs to an old version of %s which is no longer supported.\n\nPlease ensure that both of you are running the latest version and then try again.</string>
+	<string name="qr_code_too_old">The QR code you have scanned comes from an older version of %s.\n\nPlease ask your contact to upgrade to the latest version and then try again.</string>
+	<string name="qr_code_too_new">The QR code you have scanned comes from a newer version of %s.\n\nPlease upgrade to the latest version and then try again.</string>
 	<string name="camera_error">Camera error</string>
 	<string name="connecting_to_device">Connecting to device\u2026</string>
 	<string name="authenticating_with_device">Authenticating with device\u2026</string>