1 /* 2 * Copyright (C) 2015 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.netlink; 18 19 import static android.net.util.SocketUtils.makeNetlinkSocketAddress; 20 import static android.system.OsConstants.AF_NETLINK; 21 import static android.system.OsConstants.EIO; 22 import static android.system.OsConstants.EPROTO; 23 import static android.system.OsConstants.ETIMEDOUT; 24 import static android.system.OsConstants.SOCK_DGRAM; 25 import static android.system.OsConstants.SOL_SOCKET; 26 import static android.system.OsConstants.SO_RCVBUF; 27 import static android.system.OsConstants.SO_RCVTIMEO; 28 import static android.system.OsConstants.SO_SNDTIMEO; 29 30 import android.net.util.SocketUtils; 31 import android.system.ErrnoException; 32 import android.system.Os; 33 import android.system.StructTimeval; 34 import android.util.Log; 35 36 import java.io.FileDescriptor; 37 import java.io.IOException; 38 import java.io.InterruptedIOException; 39 import java.net.SocketException; 40 import java.nio.ByteBuffer; 41 import java.nio.ByteOrder; 42 43 44 /** 45 * NetlinkSocket 46 * 47 * A small static class to assist with AF_NETLINK socket operations. 48 * 49 * @hide 50 */ 51 public class NetlinkSocket { 52 private static final String TAG = "NetlinkSocket"; 53 54 public static final int DEFAULT_RECV_BUFSIZE = 8 * 1024; 55 public static final int SOCKET_RECV_BUFSIZE = 64 * 1024; 56 sendOneShotKernelMessage(int nlProto, byte[] msg)57 public static void sendOneShotKernelMessage(int nlProto, byte[] msg) throws ErrnoException { 58 final String errPrefix = "Error in NetlinkSocket.sendOneShotKernelMessage"; 59 final long IO_TIMEOUT = 300L; 60 61 final FileDescriptor fd = forProto(nlProto); 62 63 try { 64 connectToKernel(fd); 65 sendMessage(fd, msg, 0, msg.length, IO_TIMEOUT); 66 final ByteBuffer bytes = recvMessage(fd, DEFAULT_RECV_BUFSIZE, IO_TIMEOUT); 67 // recvMessage() guaranteed to not return null if it did not throw. 68 final NetlinkMessage response = NetlinkMessage.parse(bytes); 69 if (response != null && response instanceof NetlinkErrorMessage && 70 (((NetlinkErrorMessage) response).getNlMsgError() != null)) { 71 final int errno = ((NetlinkErrorMessage) response).getNlMsgError().error; 72 if (errno != 0) { 73 // TODO: consider ignoring EINVAL (-22), which appears to be 74 // normal when probing a neighbor for which the kernel does 75 // not already have / no longer has a link layer address. 76 Log.e(TAG, errPrefix + ", errmsg=" + response.toString()); 77 // Note: convert kernel errnos (negative) into userspace errnos (positive). 78 throw new ErrnoException(response.toString(), Math.abs(errno)); 79 } 80 } else { 81 final String errmsg; 82 if (response == null) { 83 bytes.position(0); 84 errmsg = "raw bytes: " + NetlinkConstants.hexify(bytes); 85 } else { 86 errmsg = response.toString(); 87 } 88 Log.e(TAG, errPrefix + ", errmsg=" + errmsg); 89 throw new ErrnoException(errmsg, EPROTO); 90 } 91 } catch (InterruptedIOException e) { 92 Log.e(TAG, errPrefix, e); 93 throw new ErrnoException(errPrefix, ETIMEDOUT, e); 94 } catch (SocketException e) { 95 Log.e(TAG, errPrefix, e); 96 throw new ErrnoException(errPrefix, EIO, e); 97 } finally { 98 try { 99 SocketUtils.closeSocket(fd); 100 } catch (IOException e) { 101 // Nothing we can do here 102 } 103 } 104 } 105 forProto(int nlProto)106 public static FileDescriptor forProto(int nlProto) throws ErrnoException { 107 final FileDescriptor fd = Os.socket(AF_NETLINK, SOCK_DGRAM, nlProto); 108 Os.setsockoptInt(fd, SOL_SOCKET, SO_RCVBUF, SOCKET_RECV_BUFSIZE); 109 return fd; 110 } 111 connectToKernel(FileDescriptor fd)112 public static void connectToKernel(FileDescriptor fd) throws ErrnoException, SocketException { 113 Os.connect(fd, makeNetlinkSocketAddress(0, 0)); 114 } 115 checkTimeout(long timeoutMs)116 private static void checkTimeout(long timeoutMs) { 117 if (timeoutMs < 0) { 118 throw new IllegalArgumentException("Negative timeouts not permitted"); 119 } 120 } 121 122 /** 123 * Wait up to |timeoutMs| (or until underlying socket error) for a 124 * netlink message of at most |bufsize| size. 125 * 126 * Multi-threaded calls with different timeouts will cause unexpected results. 127 */ recvMessage(FileDescriptor fd, int bufsize, long timeoutMs)128 public static ByteBuffer recvMessage(FileDescriptor fd, int bufsize, long timeoutMs) 129 throws ErrnoException, IllegalArgumentException, InterruptedIOException { 130 checkTimeout(timeoutMs); 131 132 Os.setsockoptTimeval(fd, SOL_SOCKET, SO_RCVTIMEO, StructTimeval.fromMillis(timeoutMs)); 133 134 ByteBuffer byteBuffer = ByteBuffer.allocate(bufsize); 135 int length = Os.read(fd, byteBuffer); 136 if (length == bufsize) { 137 Log.w(TAG, "maximum read"); 138 } 139 byteBuffer.position(0); 140 byteBuffer.limit(length); 141 byteBuffer.order(ByteOrder.nativeOrder()); 142 return byteBuffer; 143 } 144 145 /** 146 * Send a message to a peer to which this socket has previously connected, 147 * waiting at most |timeoutMs| milliseconds for the send to complete. 148 * 149 * Multi-threaded calls with different timeouts will cause unexpected results. 150 */ sendMessage( FileDescriptor fd, byte[] bytes, int offset, int count, long timeoutMs)151 public static int sendMessage( 152 FileDescriptor fd, byte[] bytes, int offset, int count, long timeoutMs) 153 throws ErrnoException, IllegalArgumentException, InterruptedIOException { 154 checkTimeout(timeoutMs); 155 Os.setsockoptTimeval(fd, SOL_SOCKET, SO_SNDTIMEO, StructTimeval.fromMillis(timeoutMs)); 156 return Os.write(fd, bytes, offset, count); 157 } 158 } 159