TODO: store this is in a database.
+ */ + @Nullable + private static Integer password; + + /** + * Indicates whether we are pairing. If this is {@code true} then we have written the + * set-broadcast-id command, and should disconnect after the write succeeds. + */ + private boolean pairing = false; public BluetoothTrisaBodyAnalyze(Context context) { super(context); @@ -83,6 +103,7 @@ public class BluetoothTrisaBodyAnalyze extends BluetoothCommunication { @Override public void connect(String hwAddress) { Timber.i("connect(\"%s\")", hwAddress); + this.hwAddress = hwAddress; super.connect(hwAddress); } @@ -97,27 +118,44 @@ public class BluetoothTrisaBodyAnalyze extends BluetoothCommunication { Timber.i("nextInitCmd(%d)", stateNr); switch (stateNr) { case 0: + // Register for notifications of the measurement characteristic. setIndicationOn( WEIGHT_SCALE_SERVICE_UUID, MEASUREMENT_CHARACTERISTIC_UUID, CLIENT_CHARACTERISTIC_CONFIGURATION_DESCRIPTOR_UUID); - return true; + return true; // more commands follow case 1: + // Register for notifications of the command upload characteristic. + // + // This is the last init command, which causes a switch to the main state machine + // immediately after. This is important because we should be in the main state + // to handle pairing correctly. setIndicationOn( WEIGHT_SCALE_SERVICE_UUID, UPLOAD_COMMAND_CHARACTERISTIC_UUID, CLIENT_CHARACTERISTIC_CONFIGURATION_DESCRIPTOR_UUID); - return true; - + // falls through default: - return false; + return false; // no more commands } } @Override protected boolean nextBluetoothCmd(int stateNr) { Timber.i("nextBluetoothCmd(%d)", stateNr); - return false; + switch (stateNr) { + case 0: + default: + return false; // no more commands + + case 1: + // This state is triggered by the write in onPasswordReceived() + if (pairing) { + pairing = false; + disconnect(true); + } + return false; // no more commands; + } } @Override @@ -125,10 +163,10 @@ public class BluetoothTrisaBodyAnalyze extends BluetoothCommunication { Timber.i("nextCleanUpCmd(%d)", stateNr); switch (stateNr) { case 0: - writeCommand(disconnectCommand()); - return true; + writeCommand(DOWNLOAD_INFORMATION_ENABLE_DISCONNECT_COMMAND); + // falls through default: - return false; + return false; // no more commands } } @@ -137,55 +175,107 @@ public class BluetoothTrisaBodyAnalyze extends BluetoothCommunication { UUID characteristicUud = gattCharacteristic.getUuid(); byte[] value = gattCharacteristic.getValue(); Timber.i("onBluetoothdataChange() characteristic=%s value=%s", characteristicUud, byteInHex(value)); - byte commandByte = value.length > 0 ? value[0] : 0; if (UPLOAD_COMMAND_CHARACTERISTIC_UUID.equals(characteristicUud)) { - switch (commandByte) { - case UPLOAD_PASSWORD: - // TODO: support pairing, then store this somewhere. - break; - case UPLOAD_CHALLENGE: - if (value.length < 5) { - break; - } - byte[] authCommand = new byte[] { - DOWNLOAD_INFORMATION_RESULT_COMMAND, - (byte)(value[1] ^ PASSWORD[0]), - (byte)(value[2] ^ PASSWORD[1]), - (byte)(value[3] ^ PASSWORD[2]), - (byte)(value[4] ^ PASSWORD[3])}; - writeCommand(authCommand); - int timestamp = (int)(System.currentTimeMillis()/1000 - TIMESTAMP_OFFSET_SECONDS); - byte[] setUtcCommand = new byte[]{ - DOWNLOAD_INFORMATION_UTC_COMMAND, - (byte)(timestamp >> 0), - (byte)(timestamp >> 8), - (byte)(timestamp >> 16), - (byte)(timestamp >> 24), - }; - writeCommand(setUtcCommand); - return; - } - - } else if (MEASUREMENT_CHARACTERISTIC_UUID.equals(characteristicUud)) { - ScaleMeasurement scaleMeasurement = parseScaleMeasurementData(value); - if (scaleMeasurement != null) { - addScaleData(scaleMeasurement); + if (value.length == 0) { + Timber.e("Missing command byte!"); return; } + byte command = value[0]; + switch (command) { + case UPLOAD_PASSWORD: + onPasswordReceived(value); + break; + case UPLOAD_CHALLENGE: + onChallengeReceived(value); + break; + default: + Timber.e("Unknown command byte received: %d", command); + } + return; } - Timber.w("Unhandled data!"); + if (MEASUREMENT_CHARACTERISTIC_UUID.equals(characteristicUud)) { + onScaleMeasurumentReceived(value); + return; + } + Timber.e("Unknown characteristic changed: %s", characteristicUud); } - private byte[] disconnectCommand() { - return new byte[]{DOWNLOAD_INFORMATION_ENABLE_DISCONNECT_COMMAND}; + private void onPasswordReceived(byte[] data) { + if (data.length < 5) { + Timber.e("Password data too short"); + return; + } + int newPassword = getInt32(data, 1); + if (password != null && password != newPassword) { + Timber.w("Replacing old password '%08x'", password); + } + Timber.i("Storing password '%08x'", newPassword); + password = newPassword; + + sendMessage(R.string.trisa_scale_pairing_succeeded, null); + + // To complete the pairing process, we must set the scale's broadcast id, and then + // disconnect. The writeCommand() call below will trigger the next state machine transition, + // which will disconnect when `pairing == true`. + pairing = true; + writeCommand(DOWNLOAD_INFORMATION_BROADCAST_ID_COMMAND, BROADCAST_ID); } - private void writeCommand(byte[] bytes) { + private void onChallengeReceived(byte[] data) { + if (data.length < 5) { + Timber.e("Challenge data too short"); + return; + } + if (password == null) { + Timber.w("Received challenge, but password is unknown."); + sendMessage(R.string.trisa_scale_not_paired, null); + disconnect(true); + return; + } + int challenge = getInt32(data, 1); + int response = challenge ^ password; + writeCommand(DOWNLOAD_INFORMATION_RESULT_COMMAND, response); + int timestamp = (int)(System.currentTimeMillis()/1000 - TIMESTAMP_OFFSET_SECONDS); + writeCommand(DOWNLOAD_INFORMATION_UTC_COMMAND, timestamp); + } + + private void onScaleMeasurumentReceived(byte[] data) { + ScaleMeasurement scaleMeasurement = parseScaleMeasurementData(data); + if (scaleMeasurement == null) { + Timber.e("Failed to parse scale measure measurement data: %s", byteInHex(data)); + return; + } + addScaleData(scaleMeasurement); + } + + /** Write a single command byte, without any arguments. */ + private void writeCommand(byte commandByte) { + writeCommandBytes(new byte[]{commandByte}); + } + + /** + * Write a command with a 32-bit integer argument. + * + *The command string consists of the command byte followed by 4 bytes: the argument + * encoded in little-endian byte order.
+ */ + private void writeCommand(byte commandByte, int argument) { + writeCommandBytes(new byte[]{ + commandByte, + (byte) (argument >> 0), + (byte) (argument >> 8), + (byte) (argument >> 16), + (byte) (argument >> 24), + }); + } + + private void writeCommandBytes(byte[] bytes) { + Timber.d("writeCommand bytes=%s", byteInHex(bytes)); writeBytes(WEIGHT_SCALE_SERVICE_UUID, DOWNLOAD_COMMAND_CHARACTERISTIC_UUID, bytes); } @Nullable - private ScaleMeasurement parseScaleMeasurementData(byte[] data) { + private static ScaleMeasurement parseScaleMeasurementData(byte[] data) { // Byte 0 contains info. // Byte 1-4 contains weight. // Byte 5-8 contains timestamp, if bit 0 in info byte is set. @@ -216,7 +306,7 @@ public class BluetoothTrisaBodyAnalyze extends BluetoothCommunication { *The first three little-endian bytes form the 24-bit mantissa. The last byte contains the
* signed exponent, applied in base 10.
*/
- private double getBase10Float(byte[] data, int offset) {
+ private static double getBase10Float(byte[] data, int offset) {
int mantissa = (data[offset] & 0xff) | ((data[offset + 1] & 0xff) << 8) |
((data[offset + 2] & 0xff) << 16);
int exponent = data[offset + 3]; // note: byte is signed.
diff --git a/android_app/app/src/main/res/values/strings.xml b/android_app/app/src/main/res/values/strings.xml
index 8783c2d1..e3f18afe 100644
--- a/android_app/app/src/main/res/values/strings.xml
+++ b/android_app/app/src/main/res/values/strings.xml
@@ -169,6 +169,8 @@