1 /*
2  * Copyright (C) 2019 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package android.net;
18 
19 import android.annotation.NonNull;
20 import android.os.ParcelFileDescriptor;
21 import android.os.RemoteException;
22 import android.util.Log;
23 
24 import java.io.FileDescriptor;
25 import java.util.concurrent.Executor;
26 
27 /** @hide */
28 final class TcpSocketKeepalive extends SocketKeepalive {
29 
TcpSocketKeepalive(@onNull IConnectivityManager service, @NonNull Network network, @NonNull ParcelFileDescriptor pfd, @NonNull Executor executor, @NonNull Callback callback)30     TcpSocketKeepalive(@NonNull IConnectivityManager service,
31             @NonNull Network network,
32             @NonNull ParcelFileDescriptor pfd,
33             @NonNull Executor executor,
34             @NonNull Callback callback) {
35         super(service, network, pfd, executor, callback);
36     }
37 
38     /**
39      * Starts keepalives. {@code mSocket} must be a connected TCP socket.
40      *
41      * - The application must not write to or read from the socket after calling this method, until
42      *   onDataReceived, onStopped, or onError are called. If it does, the keepalive will fail
43      *   with {@link #ERROR_SOCKET_NOT_IDLE}, or {@code #ERROR_INVALID_SOCKET} if the socket
44      *   experienced an error (as in poll(2) returned POLLERR or POLLHUP); if this happens, the data
45      *   received from the socket may be invalid, and the socket can't be recovered.
46      * - If the socket has data in the send or receive buffer, then this call will fail with
47      *   {@link #ERROR_SOCKET_NOT_IDLE} and can be retried after the data has been processed.
48      *   An app could ensure this by using an application-layer protocol to receive acknowledgement
49      *   that indicates all data has been delivered to server, e.g. HTTP 200 OK.
50      *   Then the app could go into keepalive mode after reading all remaining data within the
51      *   acknowledgement.
52      */
53     @Override
startImpl(int intervalSec)54     void startImpl(int intervalSec) {
55         mExecutor.execute(() -> {
56             try {
57                 final FileDescriptor fd = mPfd.getFileDescriptor();
58                 mService.startTcpKeepalive(mNetwork, fd, intervalSec, mCallback);
59             } catch (RemoteException e) {
60                 Log.e(TAG, "Error starting packet keepalive: ", e);
61                 throw e.rethrowFromSystemServer();
62             }
63         });
64     }
65 
66     @Override
stopImpl()67     void stopImpl() {
68         mExecutor.execute(() -> {
69             try {
70                 if (mSlot != null) {
71                     mService.stopKeepalive(mNetwork, mSlot);
72                 }
73             } catch (RemoteException e) {
74                 Log.e(TAG, "Error stopping packet keepalive: ", e);
75                 throw e.rethrowFromSystemServer();
76             }
77         });
78     }
79 }
80