BLE communication refactoring

app/build.gradle

@@ -23,11 +23,15 @@ android {
         if (project.hasProperty('strictCheck')) {
             warningsAsErrors = strictCheck
         }
+
         textReport true
     }
 }
 
 repositories {
+    maven {
+        url "file://${System.properties['user.home']}/.m2/repository"
+    }
     maven {
         url 'http://releases.marmeladburk.fidesmo.com'
     }
@@ -45,6 +49,6 @@ dependencies {
     testCompile 'junit:junit:4.12'
     compile 'com.android.support:appcompat-v7:25.3.1'
     compile 'io.reactivex:rxjava:1.0.13'
-    compile 'com.fidesmo:ble-client-android:0.1.10'
+    compile 'com.fidesmo:ble-client-android:0.1.11'
     compile 'com.fidesmo:nordpol-android:0.1.18'
 }

app/src/main/java/com/fidesmo/ble/client/BlePeripheralService.java

@@ -17,6 +17,7 @@
 import android.support.v4.content.LocalBroadcastManager;
 import android.util.Log;
 import android.widget.Toast;
+
 import com.fidesmo.ble.client.protocol.FragmentationProtocol;
 import com.fidesmo.ble.client.protocol.PacketDefragmenter;
 import com.fidesmo.ble.client.protocol.PacketFragmenter;
@@ -213,28 +214,17 @@ public void onCharacteristicReadRequest(BluetoothDevice device, int requestId, i
                     return ;
                 }
 
+                if (characteristic.getUuid().equals(BleCard.APDU_READ_CHARACTERISTIC_UUID) && currentResponsePacket != null) {
 
-                if (!characteristic.getUuid().equals(BleCard.APDU_READ_CHARACTERISTIC_UUID)) {
-                    gattServer.sendResponse(device, requestId, BluetoothGatt.GATT_FAILURE, 0, null);
-                    log("Unsupported characteristics read: " + characteristic.getUuid());
-                    return ;
-                }
-
-                if (currentResponsePacket == null) {
-                    log("No answer ready yet");
-                    gattServer.sendResponse(device, requestId, BluetoothGatt.GATT_FAILURE, 0, null);
-                    return;
-                }
-
-                if (currentResponsePacket.hasMoreData()) {
-                    gattServer.sendResponse(device, requestId, BluetoothGatt.GATT_SUCCESS, offset, currentResponsePacket.nextFragment());
-                } else {
-                    gattServer.sendResponse(device, requestId, BluetoothGatt.GATT_SUCCESS, offset, new byte[]{0});
-                }
-
+                    if (offset == 0 && currentResponsePacket.hasMoreData()) {
+                        // save Fidesmo's internal packet inside characteristic
+                        characteristic.setValue(currentResponsePacket.nextFragment());
+                    }
 
-                if (!currentResponsePacket.hasMoreData()) {
-                    currentResponsePacket = null;
+                    int chunkSize = characteristic.getValue().length - offset;
+                    byte[] chunk = new byte[chunkSize];
+                    System.arraycopy(characteristic.getValue(), offset, chunk, 0, chunkSize);
+                    gattServer.sendResponse(device, requestId, BluetoothGatt.GATT_SUCCESS, offset, chunk);
                 }
             }
 
@@ -249,37 +239,20 @@ public void onCharacteristicWriteRequest(final BluetoothDevice device, final int
                     ", flags: prepared=" + preparedWrite + ", respNeeded=" + responseNeeded + ", offset: " + offset
                 );
 
-                if (responseNeeded) {
-                    BleUtils.retryCall(new Callable<Boolean>() {
-                        @Override
-                        public Boolean call() throws Exception {
-                            return gattServer.sendResponse(device, requestId, BluetoothGatt.GATT_SUCCESS, 0, new byte[]{0});
-                        }
-                    });
-                }
-
-                if (offset != 0) {
-                    log("Offset is not zero: " + offset);
-                    return;
-                }
-
                 if(APDU_CONVERSATION_FINISHED_CHARACTERISTIC_UUID.equals(characteristic.getUuid())) {
                     finishConversation();
                     return;
                 }
 
-
-                if (currentPacketBuilder == null) {
-                    log("Starting APDU request session");
-                    currentPacketBuilder = fragmentationProtocol.deframenter();
+                if (preparedWrite) {
+                    onWriteBuffer(value);
+                }else {
+                    onWritePacket(value);
                 }
 
-                currentPacketBuilder.append(value);
-
-                if (currentPacketBuilder.complete()) {
-                    log("Packet received");
-                    sendBleAPDUToActivity(currentPacketBuilder.getBuffer());
-                    currentPacketBuilder = null;
+                if (gattServer != null && responseNeeded) {
+                    // need to give the same values we got as an reply, in order to get next possible part.
+                    gattServer.sendResponse(device, requestId, BluetoothGatt.GATT_SUCCESS, 0, value);
                 }
             }
 
@@ -300,8 +273,10 @@ public void onDescriptorWriteRequest(BluetoothDevice device, int requestId, Blue
 
             @Override
             public void onExecuteWrite(BluetoothDevice device, int requestId, boolean execute) {
+                super.onExecuteWrite(device, requestId, execute);
                 log("onExecuteWrite(" + requestId + "), execute: " + execute);
-                gattServer.sendResponse(device, requestId, BluetoothGatt.GATT_SUCCESS, 0, null);
+                gattServer.sendResponse(device, requestId, BluetoothGatt.GATT_SUCCESS, 0, new byte[] {});
+                onExecuteWriteBuffer(execute);
             }
 
             @Override
@@ -370,6 +345,38 @@ public void onMtuChanged(BluetoothDevice device, int mtu) {
         }
     }
 
+    private void onWriteBuffer(byte[] buffer) {
+        if (currentPacketBuilder == null) {
+            currentPacketBuilder = fragmentationProtocol.deframenter();
+            currentPacketBuilder.appendPacket(buffer);
+        } else {
+            currentPacketBuilder.addPacketFragment(buffer);
+        }
+    }
+
+    private void onWritePacket(byte[] buffer) {
+        if (currentPacketBuilder == null) {
+            currentPacketBuilder = fragmentationProtocol.deframenter();
+            currentPacketBuilder.appendPacket(buffer);
+            onApduBufferReady();
+        }
+    }
+
+    private void onExecuteWriteBuffer(boolean execute) {
+        if (execute) {
+            onApduBufferReady();
+        } else {
+            currentPacketBuilder = null;
+        }
+    }
+
+    private void onApduBufferReady() {
+        if (currentPacketBuilder.isCompleted()) {
+            sendBleAPDUToActivity(currentPacketBuilder.fullData());
+            currentPacketBuilder = null;
+        }
+    }
+
     private void finishConversation() {
         Intent intent = new Intent(BlePeripheralService.CONVERSATION_FINISHED);
         LocalBroadcastManager.getInstance(BlePeripheralService.this).sendBroadcast(intent);

app/src/main/java/com/fidesmo/ble/client/MainActivity.java

@@ -23,6 +23,7 @@
 import android.widget.Toast;
 import com.fidesmo.ble.R;
 import com.fidesmo.ble.client.apdu.CardInfoClient;
+import com.fidesmo.ble.client.apdu.SimpleApduFragmenter;
 import com.fidesmo.ble.client.models.CardInfo;
 import com.fidesmo.ble.client.models.CardOperation;
 import nordpol.IsoCard;
@@ -50,6 +51,8 @@ public class MainActivity extends AppCompatActivity implements OnDiscoveredTagLi
 
     private LinkedList<CardOperation> pendingOperations = new LinkedList<>();
 
+    private SimpleApduFragmenter apduFragmenter = new SimpleApduFragmenter();
+
     private BroadcastReceiver apduReceiver = new BroadcastReceiver() {
         @Override
         public void onReceive(Context context, Intent intent) {
@@ -101,7 +104,6 @@ public void onReceive(Context context, Intent intent) {
         nfcTagDispatcher = TagDispatcher.get(this, this, false, false, false, true, false, true);
     }
 
-
     @Override
     public void tagDiscovered(Tag tag) {
         try {
@@ -271,9 +273,12 @@ private void processPendingCardOperations() {
                 }
 
                 Log.i(TAG, "Trying to transcieve data to a card: " + byteArrayToString(operation.getRequest()));
-
-                byte[] result = nfcCard.transceive(operation.getRequest());
-                operation.setResponse(result);
+                byte[][] apdus = apduFragmenter.decode(operation.getRequest());
+                byte[][] response = new byte[apdus.length][];
+                for (int i = 0; i < apdus.length; i ++) {
+                    response[i] = nfcCard.transceive(apdus[i]);
+                }
+                operation.setResponse(apduFragmenter.encode(response));
                 sendResponse(operation);
 
                 operation = pendingOperations.poll();

app/src/main/java/com/fidesmo/ble/client/apdu/ApduFragmenter.java

@@ -0,0 +1,8 @@
+package com.fidesmo.ble.client.apdu;
+
+public interface ApduFragmenter {
+
+    byte[][] decode(byte[] encodedApdus);
+    byte[] encode(byte[][] apdus);
+
+}

app/src/main/java/com/fidesmo/ble/client/apdu/SimpleApduFragmenter.java

@@ -0,0 +1,64 @@
+package com.fidesmo.ble.client.apdu;
+
+import android.util.Log;
+
+import com.fidesmo.ble.client.BleUtils;
+import com.fidesmo.ble.client.Utils;
+
+/**
+ * This class splits big byte buffer formed by a list of apdus
+ * into a list of single apdus.
+ * Spec: https://github.com/fidesmo/apdu-over-ble/blob/master/spec/apdu-service-spec.md
+ *
+ * Created by Angel Anton on 30/05/17.
+ */
+
+public class SimpleApduFragmenter implements ApduFragmenter {
+
+    private int TOTAL_HEADER_SIZE = 2;
+    private int HEADER_SIZE = 2;
+
+    @Override
+    public byte[][] decode(byte[] encodedApdus) {
+        int totalNo = BleUtils.unpackInt2(encodedApdus, 0);
+        byte[][] apdus = new byte[totalNo][];
+        int acc = TOTAL_HEADER_SIZE;
+
+        for (int i = 0; i < totalNo; i++) {
+            int apduSize = BleUtils.unpackInt2(encodedApdus, acc);
+            byte[] apdu = new byte[apduSize];
+            acc += HEADER_SIZE;
+            System.arraycopy(encodedApdus, acc, apdu, 0, apduSize);
+            apdus[i] = apdu;
+            acc += apduSize;
+        }
+        return apdus;
+    }
+
+    @Override
+    public byte[] encode(byte[][] apdus) {
+        byte[] buffer = new byte[2];
+        BleUtils.packInt2(apdus.length, buffer, 0);
+        int acc = TOTAL_HEADER_SIZE;
+
+        for (int i = 0; i < apdus.length; i++) {
+            byte[] apdu = apdus[i];
+            buffer = ensureBuffer(buffer, buffer.length + HEADER_SIZE + apdu.length);
+            BleUtils.packInt2(apdu.length, buffer, acc);
+            acc += HEADER_SIZE;
+            System.arraycopy(apdu, 0, buffer, acc, apdu.length);
+            acc += apdu.length;
+        }
+
+        return buffer;
+    }
+
+    private byte[] ensureBuffer(byte[] buffer, int size) {
+        if (buffer.length < size) {
+            byte[] oldBuf = buffer;
+            buffer = new byte[size]; // + 256?
+            System.arraycopy(oldBuf, 0, buffer, 0, oldBuf.length);
+        }
+        return buffer;
+    }
+}