tls-psk: handle back button

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/network/KeyTransferInteractor.java

@@ -83,12 +83,12 @@ public class KeyTransferInteractor {
 
     private static class TransferThread extends Thread {
         private final Handler handler;
-        private final KeyTransferCallback callback;
         private final byte[] presharedKey;
         private final boolean isServer;
         private final String clientHost;
         private final Integer clientPort;
 
+        private KeyTransferCallback callback;
         private SSLServerSocket serverSocket;
         private byte[] dataToSend;
         private String sendPassthrough;
@@ -174,9 +174,12 @@ public class KeyTransferInteractor {
             OutputStream outputStream = new BufferedOutputStream(socket.getOutputStream());
 
             socket.setSoTimeout(500);
-            while (!isInterrupted() && socket.isConnected()) {
+            while (!isInterrupted() && socket.isConnected() && !socket.isClosed()) {
                 sendDataIfAvailable(socket, outputStream);
-                receiveDataIfAvailable(socket, bufferedReader);
+                boolean connectionTerminated = receiveDataIfAvailable(socket, bufferedReader);
+                if (connectionTerminated) {
+                    break;
+                }
             }
             Log.d(Constants.TAG, "disconnected");
             invokeListener(CONNECTION_LOST, null);
@@ -191,7 +194,6 @@ public class KeyTransferInteractor {
             }
 
             if (firstLine == null) {
-                invokeListener(CONNECTION_LOST, null);
                 return true;
             }
 
@@ -200,7 +202,7 @@ public class KeyTransferInteractor {
             socket.setSoTimeout(500);
 
             invokeListener(CONNECTION_RECEIVE_OK, receivedData);
-            return true;
+            return false;
         }
 
         private boolean sendDataIfAvailable(Socket socket, OutputStream outputStream) throws IOException {
@@ -280,6 +282,8 @@ public class KeyTransferInteractor {
 
         @Override
         public void interrupt() {
+            callback = null;
+
             super.interrupt();
 
             if (serverSocket != null) {

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/transfer/presenter/TransferPresenter.java

@@ -63,6 +63,7 @@ import org.sufficientlysecure.keychain.util.Log;
 @RequiresApi(api = VERSION_CODES.LOLLIPOP)
 public class TransferPresenter implements KeyTransferCallback, LoaderCallbacks<List<SecretKeyItem>>,
         OnClickTransferKeyListener, OnClickImportKeyListener {
+    public static final String BACKSTACK_TAG_TRANSFER = "transfer";
     private final Context context;
     private final TransferMvpView view;
     private final LoaderManager loaderManager;
@@ -94,7 +95,7 @@ public class TransferPresenter implements KeyTransferCallback, LoaderCallbacks<L
         loaderManager.restartLoader(loaderId, null, this);
 
         if (keyTransferServerInteractor == null && keyTransferClientInteractor == null && !wasConnected) {
-            connectionStartListen();
+            connectionResetAndStartListen();
         }
     }
 
@@ -112,6 +113,12 @@ public class TransferPresenter implements KeyTransferCallback, LoaderCallbacks<L
         connectionStartConnect(qrCodeContent);
     }
 
+    public void onUiBackStackPop() {
+        if (wasConnected) {
+            connectionResetAndStartListen();
+        }
+    }
+
     @Override
     public void onUiClickTransferKey(long masterKeyId) {
         try {
@@ -181,14 +188,15 @@ public class TransferPresenter implements KeyTransferCallback, LoaderCallbacks<L
 
         secretKeyAdapter.clearFinishedItems();
         view.showConnectionEstablished(otherName);
+        view.addFakeBackStackItem(BACKSTACK_TAG_TRANSFER);
     }
 
     @Override
     public void onConnectionLost() {
         Log.d(Constants.TAG, "Lost connection!");
         if (!wasConnected) {
-            connectionStartListen();
             view.showErrorConnectionFailed();
+            connectionResetAndStartListen();
         } else {
             view.showViewDisconnected();
             secretKeyAdapter.disableAll();
@@ -237,7 +245,8 @@ public class TransferPresenter implements KeyTransferCallback, LoaderCallbacks<L
         keyTransferClientInteractor.connectToServer(qrCodeContent, this);
     }
 
-    private void connectionStartListen() {
+    private void connectionResetAndStartListen() {
+        wasConnected = false;
         connectionClear();
 
         keyTransferServerInteractor = new KeyTransferInteractor();
@@ -302,5 +311,7 @@ public class TransferPresenter implements KeyTransferCallback, LoaderCallbacks<L
         void setReceivedKeyAdapter(Adapter secretKeyAdapter);
 
         <T extends Parcelable, S extends OperationResult> CryptoOperationHelper<T,S> createCryptoOperationHelper(Callback<T, S> callback);
+
+        void addFakeBackStackItem(String tag);
     }
 }

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/transfer/view/TransferFragment.java

@@ -27,6 +27,8 @@ import android.os.Parcelable;
 import android.support.annotation.Nullable;
 import android.support.annotation.RequiresApi;
 import android.support.v4.app.Fragment;
+import android.support.v4.app.FragmentManager;
+import android.support.v4.app.FragmentManager.OnBackStackChangedListener;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.RecyclerView.Adapter;
 import android.view.LayoutInflater;
@@ -194,6 +196,27 @@ public class TransferFragment extends Fragment implements TransferMvpView {
         result.createNotify(getActivity()).show();
     }
 
+    @Override
+    public void addFakeBackStackItem(final String tag) {
+        FragmentManager fragmentManager = getFragmentManager();
+
+        fragmentManager.beginTransaction()
+                .addToBackStack(tag)
+                .commitAllowingStateLoss();
+        fragmentManager.executePendingTransactions();
+
+        fragmentManager.addOnBackStackChangedListener(new OnBackStackChangedListener() {
+            @Override
+            public void onBackStackChanged() {
+                FragmentManager fragMan = getFragmentManager();
+                fragMan.popBackStack(tag, FragmentManager.POP_BACK_STACK_INCLUSIVE);
+                fragMan.removeOnBackStackChangedListener(this);
+
+                presenter.onUiBackStackPop();
+            }
+        });
+    }
+
     @Override
     public void onActivityResult(int requestCode, int resultCode, Intent data) {
         if (currentCryptoOperationHelper != null &&