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sctp.c
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1 /*
2  * SCTP protocol
3  * Copyright (c) 2012 Luca Barbato
4  *
5  * This file is part of Libav.
6  *
7  * Libav is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * Libav is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  *
25  * sctp url_protocol
26  *
27  * url syntax: sctp://host:port[?option=val...]
28  * option: 'listen' : listen for an incoming connection
29  * 'max_streams=n' : set the maximum number of streams
30  * 'reuse=1' : enable reusing the socket [TBD]
31  *
32  * by setting the maximum number of streams the protocol will use the
33  * first two bytes of the incoming/outgoing buffer to store the
34  * stream number of the packet being read/written.
35  * @see sctp_read
36  * @see sctp_write
37  */
38 
39 
40 #include <netinet/in.h>
41 #include <netinet/sctp.h>
42 
43 #include "config.h"
44 
45 #if HAVE_POLL_H
46 #include <poll.h>
47 #endif
48 
49 #include "libavutil/intreadwrite.h"
50 #include "libavutil/parseutils.h"
51 #include "avformat.h"
52 #include "internal.h"
53 #include "network.h"
54 #include "os_support.h"
55 #include "url.h"
56 
57 /*
58  * The sctp_recvmsg and sctp_sendmsg functions are part of the user
59  * library that offers support for the SCTP kernel Implementation.
60  * To avoid build-time clashes the functions sport an ff_-prefix here.
61  * The main purpose of this code is to provide the SCTP Socket API
62  * mappings for user applications to interface with SCTP in the kernel.
63  *
64  * This implementation is based on the Socket API Extensions for SCTP
65  * defined in <draft-ietf-tsvwg-sctpsocket-10.txt>
66  *
67  * Copyright (c) 2003 International Business Machines, Corp.
68  *
69  * Written or modified by:
70  * Ryan Layer <rmlayer@us.ibm.com>
71  */
72 
73 static int ff_sctp_recvmsg(int s, void *msg, size_t len, struct sockaddr *from,
74  socklen_t *fromlen, struct sctp_sndrcvinfo *sinfo,
75  int *msg_flags)
76 {
77  int recvb;
78  struct iovec iov;
79  char incmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
80  struct msghdr inmsg = { 0 };
81  struct cmsghdr *cmsg = NULL;
82 
83  iov.iov_base = msg;
84  iov.iov_len = len;
85 
86  inmsg.msg_name = from;
87  inmsg.msg_namelen = fromlen ? *fromlen : 0;
88  inmsg.msg_iov = &iov;
89  inmsg.msg_iovlen = 1;
90  inmsg.msg_control = incmsg;
91  inmsg.msg_controllen = sizeof(incmsg);
92 
93  if ((recvb = recvmsg(s, &inmsg, msg_flags ? *msg_flags : 0)) < 0)
94  return recvb;
95 
96  if (fromlen)
97  *fromlen = inmsg.msg_namelen;
98  if (msg_flags)
99  *msg_flags = inmsg.msg_flags;
100 
101  for (cmsg = CMSG_FIRSTHDR(&inmsg); cmsg != NULL;
102  cmsg = CMSG_NXTHDR(&inmsg, cmsg)) {
103  if ((IPPROTO_SCTP == cmsg->cmsg_level) &&
104  (SCTP_SNDRCV == cmsg->cmsg_type))
105  break;
106  }
107 
108  /* Copy sinfo. */
109  if (cmsg)
110  memcpy(sinfo, CMSG_DATA(cmsg), sizeof(struct sctp_sndrcvinfo));
111 
112  return recvb;
113 }
114 
115 static int ff_sctp_send(int s, const void *msg, size_t len,
116  const struct sctp_sndrcvinfo *sinfo, int flags)
117 {
118  struct msghdr outmsg;
119  struct iovec iov;
120 
121  outmsg.msg_name = NULL;
122  outmsg.msg_namelen = 0;
123  outmsg.msg_iov = &iov;
124  iov.iov_base = (void*)msg;
125  iov.iov_len = len;
126  outmsg.msg_iovlen = 1;
127  outmsg.msg_controllen = 0;
128 
129  if (sinfo) {
130  char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
131  struct cmsghdr *cmsg;
132 
133  outmsg.msg_control = outcmsg;
134  outmsg.msg_controllen = sizeof(outcmsg);
135  outmsg.msg_flags = 0;
136 
137  cmsg = CMSG_FIRSTHDR(&outmsg);
138  cmsg->cmsg_level = IPPROTO_SCTP;
139  cmsg->cmsg_type = SCTP_SNDRCV;
140  cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
141 
142  outmsg.msg_controllen = cmsg->cmsg_len;
143  memcpy(CMSG_DATA(cmsg), sinfo, sizeof(struct sctp_sndrcvinfo));
144  }
145 
146  return sendmsg(s, &outmsg, flags);
147 }
148 
149 typedef struct SCTPContext {
150  int fd;
153  socklen_t dest_addr_len;
154 } SCTPContext;
155 
156 static int sctp_open(URLContext *h, const char *uri, int flags)
157 {
158  struct addrinfo *ai, *cur_ai;
159  struct addrinfo hints = { 0 };
160  struct sctp_event_subscribe event = { 0 };
161  struct sctp_initmsg initparams = { 0 };
162  int port;
163  int fd = -1;
164  SCTPContext *s = h->priv_data;
165  const char *p;
166  char buf[256];
167  int ret, listen_socket = 0;
168  char hostname[1024], proto[1024], path[1024];
169  char portstr[10];
170 
171  av_url_split(proto, sizeof(proto), NULL, 0, hostname, sizeof(hostname),
172  &port, path, sizeof(path), uri);
173  if (strcmp(proto, "sctp"))
174  return AVERROR(EINVAL);
175  if (port <= 0 || port >= 65536) {
176  av_log(s, AV_LOG_ERROR, "Port missing in uri\n");
177  return AVERROR(EINVAL);
178  }
179 
180  s->max_streams = 0;
181  p = strchr(uri, '?');
182  if (p) {
183  if (av_find_info_tag(buf, sizeof(buf), "listen", p))
184  listen_socket = 1;
185  if (av_find_info_tag(buf, sizeof(buf), "max_streams", p))
186  s->max_streams = strtol(buf, NULL, 10);
187  }
188 
189  hints.ai_family = AF_UNSPEC;
190  hints.ai_socktype = SOCK_STREAM;
191  snprintf(portstr, sizeof(portstr), "%d", port);
192  ret = getaddrinfo(hostname, portstr, &hints, &ai);
193  if (ret) {
194  av_log(h, AV_LOG_ERROR, "Failed to resolve hostname %s: %s\n",
195  hostname, gai_strerror(ret));
196  return AVERROR(EIO);
197  }
198 
199  cur_ai = ai;
200 
201  fd = socket(cur_ai->ai_family, SOCK_STREAM, IPPROTO_SCTP);
202  if (fd < 0)
203  goto fail;
204 
205  s->dest_addr_len = sizeof(s->dest_addr);
206 
207  if (listen_socket) {
208  int fd1;
209  ret = bind(fd, cur_ai->ai_addr, cur_ai->ai_addrlen);
210  listen(fd, 100);
211  fd1 = accept(fd, NULL, NULL);
212  closesocket(fd);
213  fd = fd1;
214  } else
215  ret = connect(fd, cur_ai->ai_addr, cur_ai->ai_addrlen);
216 
217  ff_socket_nonblock(fd, 1);
218 
219  event.sctp_data_io_event = 1;
220  /* TODO: Subscribe to more event types and handle them */
221 
222  if (setsockopt(fd, IPPROTO_SCTP, SCTP_EVENTS, &event,
223  sizeof(event)) != 0) {
224  av_log(h, AV_LOG_ERROR,
225  "SCTP ERROR: Unable to subscribe to events\n");
226  goto fail;
227  }
228 
229  if (s->max_streams) {
230  initparams.sinit_max_instreams = s->max_streams;
231  initparams.sinit_num_ostreams = s->max_streams;
232  if (setsockopt(fd, IPPROTO_SCTP, SCTP_INITMSG, &initparams,
233  sizeof(initparams)) < 0)
234  av_log(h, AV_LOG_ERROR,
235  "SCTP ERROR: Unable to initialize socket max streams %d\n",
236  s->max_streams);
237  }
238 
239  h->priv_data = s;
240  h->is_streamed = 1;
241  s->fd = fd;
242  freeaddrinfo(ai);
243  return 0;
244 
245 fail:
246  ret = AVERROR(EIO);
247  freeaddrinfo(ai);
248  return ret;
249 }
250 
251 static int sctp_wait_fd(int fd, int write)
252 {
253  int ev = write ? POLLOUT : POLLIN;
254  struct pollfd p = { .fd = fd, .events = ev, .revents = 0 };
255  int ret;
256 
257  ret = poll(&p, 1, 100);
258  return ret < 0 ? ff_neterrno() : p.revents & ev ? 0 : AVERROR(EAGAIN);
259 }
260 
261 static int sctp_read(URLContext *h, uint8_t *buf, int size)
262 {
263  SCTPContext *s = h->priv_data;
264  int ret;
265 
266  if (!(h->flags & AVIO_FLAG_NONBLOCK)) {
267  ret = sctp_wait_fd(s->fd, 0);
268  if (ret < 0)
269  return ret;
270  }
271 
272  if (s->max_streams) {
273  /*StreamId is introduced as a 2byte code into the stream*/
274  struct sctp_sndrcvinfo info = { 0 };
275  ret = ff_sctp_recvmsg(s->fd, buf + 2, size - 2, NULL, 0, &info, 0);
276  AV_WB16(buf, info.sinfo_stream);
277  ret = ret < 0 ? ret : ret + 2;
278  } else
279  ret = recv(s->fd, buf, size, 0);
280 
281  return ret < 0 ? ff_neterrno() : ret;
282 }
283 
284 static int sctp_write(URLContext *h, const uint8_t *buf, int size)
285 {
286  SCTPContext *s = h->priv_data;
287  int ret;
288 
289  if (!(h->flags & AVIO_FLAG_NONBLOCK)) {
290  ret = sctp_wait_fd(s->fd, 1);
291  if (ret < 0)
292  return ret;
293  }
294 
295  if (s->max_streams) {
296  /*StreamId is introduced as a 2byte code into the stream*/
297  struct sctp_sndrcvinfo info = { 0 };
298  info.sinfo_stream = AV_RB16(buf);
299  if (info.sinfo_stream > s->max_streams) {
300  av_log(h, AV_LOG_ERROR, "bad input data\n");
301  return AVERROR(EINVAL);
302  }
303  ret = ff_sctp_send(s->fd, buf + 2, size - 2, &info, MSG_EOR);
304  } else
305  ret = send(s->fd, buf, size, 0);
306 
307  return ret < 0 ? ff_neterrno() : ret;
308 }
309 
310 static int sctp_close(URLContext *h)
311 {
312  SCTPContext *s = h->priv_data;
313  closesocket(s->fd);
314  return 0;
315 }
316 
318 {
319  SCTPContext *s = h->priv_data;
320  return s->fd;
321 }
322 
324  .name = "sctp",
325  .url_open = sctp_open,
326  .url_read = sctp_read,
327  .url_write = sctp_write,
328  .url_close = sctp_close,
329  .url_get_file_handle = sctp_get_file_handle,
330  .priv_data_size = sizeof(SCTPContext),
332 };