1 /* 2 * Copyright (C) 2016 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.util; 18 19 import android.annotation.Nullable; 20 import android.system.ErrnoException; 21 import android.system.Os; 22 import android.system.OsConstants; 23 24 import libcore.io.IoBridge; 25 26 import java.io.FileDescriptor; 27 import java.io.InterruptedIOException; 28 import java.io.IOException; 29 30 31 /** 32 * A thread that reads from a socket and passes the received packets to a 33 * subclass's handlePacket() method. The packet receive buffer is recycled 34 * on every read call, so subclasses should make any copies they would like 35 * inside their handlePacket() implementation. 36 * 37 * All public methods may be called from any thread. 38 * 39 * @hide 40 */ 41 public abstract class BlockingSocketReader { 42 public static final int DEFAULT_RECV_BUF_SIZE = 2 * 1024; 43 44 private final byte[] mPacket; 45 private final Thread mThread; 46 private volatile FileDescriptor mSocket; 47 private volatile boolean mRunning; 48 private volatile long mPacketsReceived; 49 50 // Make it slightly easier for subclasses to properly close a socket 51 // without having to know this incantation. closeSocket(@ullable FileDescriptor fd)52 public static final void closeSocket(@Nullable FileDescriptor fd) { 53 try { 54 IoBridge.closeAndSignalBlockedThreads(fd); 55 } catch (IOException ignored) {} 56 } 57 BlockingSocketReader()58 protected BlockingSocketReader() { 59 this(DEFAULT_RECV_BUF_SIZE); 60 } 61 BlockingSocketReader(int recvbufsize)62 protected BlockingSocketReader(int recvbufsize) { 63 if (recvbufsize < DEFAULT_RECV_BUF_SIZE) { 64 recvbufsize = DEFAULT_RECV_BUF_SIZE; 65 } 66 mPacket = new byte[recvbufsize]; 67 mThread = new Thread(() -> { mainLoop(); }); 68 } 69 start()70 public final boolean start() { 71 if (mSocket != null) return false; 72 73 try { 74 mSocket = createSocket(); 75 } catch (Exception e) { 76 logError("Failed to create socket: ", e); 77 return false; 78 } 79 80 if (mSocket == null) return false; 81 82 mRunning = true; 83 mThread.start(); 84 return true; 85 } 86 stop()87 public final void stop() { 88 mRunning = false; 89 closeSocket(mSocket); 90 mSocket = null; 91 } 92 isRunning()93 public final boolean isRunning() { return mRunning; } 94 numPacketsReceived()95 public final long numPacketsReceived() { return mPacketsReceived; } 96 97 /** 98 * Subclasses MUST create the listening socket here, including setting 99 * all desired socket options, interface or address/port binding, etc. 100 */ createSocket()101 protected abstract FileDescriptor createSocket(); 102 103 /** 104 * Called by the main loop for every packet. Any desired copies of 105 * |recvbuf| should be made in here, and the underlying byte array is 106 * reused across all reads. 107 */ handlePacket(byte[] recvbuf, int length)108 protected void handlePacket(byte[] recvbuf, int length) {} 109 110 /** 111 * Called by the main loop to log errors. In some cases |e| may be null. 112 */ logError(String msg, Exception e)113 protected void logError(String msg, Exception e) {} 114 115 /** 116 * Called by the main loop just prior to exiting. 117 */ onExit()118 protected void onExit() {} 119 mainLoop()120 private final void mainLoop() { 121 while (isRunning()) { 122 final int bytesRead; 123 124 try { 125 // Blocking read. 126 // TODO: See if this can be converted to recvfrom. 127 bytesRead = Os.read(mSocket, mPacket, 0, mPacket.length); 128 if (bytesRead < 1) { 129 if (isRunning()) logError("Socket closed, exiting", null); 130 break; 131 } 132 mPacketsReceived++; 133 } catch (ErrnoException e) { 134 if (e.errno != OsConstants.EINTR) { 135 if (isRunning()) logError("read error: ", e); 136 break; 137 } 138 continue; 139 } catch (IOException ioe) { 140 if (isRunning()) logError("read error: ", ioe); 141 continue; 142 } 143 144 try { 145 handlePacket(mPacket, bytesRead); 146 } catch (Exception e) { 147 logError("Unexpected exception: ", e); 148 break; 149 } 150 } 151 152 stop(); 153 onExit(); 154 } 155 } 156