1/*
2 * Copyright 2010, 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#define LOG_TAG "RawSocket"
18
19#include "AsynchronousSocketCloseMonitor.h"
20#include "cutils/log.h"
21#include "JNIHelp.h"
22#include "JniException.h"
23#include "JniConstants.h"
24#include "NetFd.h"
25#include "NetworkUtilities.h"
26#include "ScopedUtfChars.h"
27#include "ScopedPrimitiveArray.h"
28
29#include "jni.h"
30
31#include <sys/types.h>
32#include <sys/socket.h>
33#include <linux/rtnetlink.h>
34#include <net/if.h>
35#include <linux/if_ether.h>
36#include <linux/if_packet.h>
37#include <arpa/inet.h>
38#include <errno.h>
39#include <fcntl.h>
40#include <poll.h>
41#include <netinet/ip.h>
42#include <linux/udp.h>
43
44union sockunion {
45    sockaddr sa;
46    sockaddr_ll sll;
47};
48
49/*
50 * Creates a socket suitable for raw socket operations.  The socket is
51 * bound to the interface specified by the supplied name.  The socket
52 * value is placed into the supplied FileDescriptor instance.
53 *
54 * TODO(chesnutt): consider breaking this into pieces: create a
55 * variety of constructors for different socket types, then a generic
56 * setBlocking() method followed by polymorphic bind().
57 */
58static void RawSocket_create(JNIEnv* env, jclass, jobject fileDescriptor,
59    jshort protocolType, jstring interfaceName)
60{
61
62  ScopedUtfChars ifname(env, interfaceName);
63  if (ifname.c_str() == NULL) {
64    return;
65  }
66
67  sockunion su;
68  memset(&su, 0, sizeof(su));
69  su.sll.sll_family = PF_PACKET;
70  su.sll.sll_protocol = htons(protocolType);
71  su.sll.sll_ifindex = if_nametoindex(ifname.c_str());
72  int sock = socket(PF_PACKET, SOCK_DGRAM, htons(protocolType));
73
74  if (sock == -1) {
75    ALOGE("Can't create socket %s", strerror(errno));
76    jniThrowSocketException(env, errno);
77    return;
78  }
79
80  jniSetFileDescriptorOfFD(env, fileDescriptor, sock);
81  if (!setBlocking(sock, false)) {
82    ALOGE("Can't set non-blocking mode on socket %s", strerror(errno));
83    jniThrowSocketException(env, errno);
84    return;
85  }
86
87  int err = bind(sock, &su.sa, sizeof(su));
88  if (err != 0) {
89    ALOGE("Socket bind error %s", strerror(errno));
90    jniThrowSocketException(env, errno);
91    return;
92  }
93}
94
95/*
96 * Writes the L3 (IP) packet to the raw socket supplied in the
97 * FileDescriptor instance.
98 *
99 * Assumes that the caller has validated the offset & byteCount values.
100 */
101static int RawSocket_sendPacket(JNIEnv* env, jclass, jobject fileDescriptor,
102    jstring interfaceName, jshort protocolType, jbyteArray destMac,
103    jbyteArray packet, jint offset, jint byteCount)
104{
105  NetFd fd(env, fileDescriptor);
106
107  if (fd.isClosed()) {
108    return 0;
109  }
110
111  ScopedUtfChars ifname(env, interfaceName);
112  if (ifname.c_str() == NULL) {
113    return 0;
114  }
115
116  ScopedByteArrayRO byteArray(env, packet);
117  if (byteArray.get() == NULL) {
118    return 0;
119  }
120
121  ScopedByteArrayRO mac(env, destMac);
122  if (mac.get() == NULL) {
123    return 0;
124  }
125
126  sockunion su;
127  memset(&su, 0, sizeof(su));
128  su.sll.sll_hatype = htons(1); // ARPHRD_ETHER
129  su.sll.sll_halen = mac.size();
130  memcpy(&su.sll.sll_addr, mac.get(), mac.size());
131  su.sll.sll_family = AF_PACKET;
132  su.sll.sll_protocol = htons(protocolType);
133  su.sll.sll_ifindex = if_nametoindex(ifname.c_str());
134
135  int err;
136  {
137    int intFd = fd.get();
138    AsynchronousSocketCloseMonitor monitor(intFd);
139    err = NET_FAILURE_RETRY(fd, sendto(intFd, byteArray.get() + offset,
140        byteCount, 0, &su.sa, sizeof(su)));
141  }
142
143  return err;
144}
145
146/*
147 * Reads a network packet into the user-supplied buffer.  Return the
148 * length of the packet, or a 0 if there was a timeout or an
149 * unacceptable packet was acquired.
150 *
151 * Assumes that the caller has validated the offset & byteCount values.
152 */
153static jint RawSocket_recvPacket(JNIEnv* env, jclass, jobject fileDescriptor,
154    jbyteArray packet, jint offset, jint byteCount, jint port,
155    jint timeout_millis)
156{
157  NetFd fd(env, fileDescriptor);
158  if (fd.isClosed()) {
159    return 0;
160  }
161
162  ScopedByteArrayRW body(env, packet);
163  jbyte* packetData = body.get();
164  if (packetData == NULL) {
165    return 0;
166  }
167
168  packetData += offset;
169
170  pollfd fds[1];
171  fds[0].fd = fd.get();
172  fds[0].events = POLLIN;
173  int retval = poll(fds, 1, timeout_millis);
174  if (retval <= 0) {
175    return 0;
176  }
177
178  unsigned int size = 0;
179  {
180    int packetSize = byteCount;
181    int intFd = fd.get();
182    AsynchronousSocketCloseMonitor monitor(intFd);
183    size = NET_FAILURE_RETRY(fd, read(intFd, packetData, packetSize));
184  }
185
186  if (env->ExceptionOccurred()) {
187    return 0;
188  }
189
190  if (port != -1) {
191    // quick check for UDP type & UDP port
192    // the packet is an IP header, UDP header, and UDP payload
193    if ((size < (sizeof(struct iphdr) + sizeof(struct udphdr)))) {
194      return 0;  // runt packet
195    }
196
197    u_int8_t ip_proto = ((iphdr *) packetData)->protocol;
198    if (ip_proto != IPPROTO_UDP) {
199      return 0;  // something other than UDP
200    }
201
202    __be16 destPort = htons((reinterpret_cast<udphdr*>(packetData + sizeof(iphdr)))->dest);
203    if (destPort != port) {
204      return 0; // something other than requested port
205    }
206  }
207
208  return size;
209}
210
211static JNINativeMethod gRawMethods[] = {
212  NATIVE_METHOD(RawSocket, create, "(Ljava/io/FileDescriptor;SLjava/lang/String;)V"),
213  NATIVE_METHOD(RawSocket, sendPacket, "(Ljava/io/FileDescriptor;Ljava/lang/String;S[B[BII)I"),
214  NATIVE_METHOD(RawSocket, recvPacket, "(Ljava/io/FileDescriptor;[BIIII)I"),
215};
216
217void register_libcore_net_RawSocket(JNIEnv* env) {
218  jniRegisterNativeMethods(env, "libcore/net/RawSocket", gRawMethods, NELEM(gRawMethods));
219}
220