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path: root/libavformat/sapdec.c (plain)
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1/*
2 * Session Announcement Protocol (RFC 2974) demuxer
3 * Copyright (c) 2010 Martin Storsjo
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg 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 * FFmpeg 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 FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#include "avformat.h"
23#include "libavutil/avassert.h"
24#include "libavutil/avstring.h"
25#include "libavutil/intreadwrite.h"
26#include "network.h"
27#include "os_support.h"
28#include "internal.h"
29#include "avio_internal.h"
30#include "url.h"
31#include "rtpdec.h"
32#if HAVE_POLL_H
33#include <poll.h>
34#endif
35
36struct SAPState {
37 URLContext *ann_fd;
38 AVFormatContext *sdp_ctx;
39 AVIOContext sdp_pb;
40 uint16_t hash;
41 char *sdp;
42 int eof;
43};
44
45static int sap_probe(AVProbeData *p)
46{
47 if (av_strstart(p->filename, "sap:", NULL))
48 return AVPROBE_SCORE_MAX;
49 return 0;
50}
51
52static int sap_read_close(AVFormatContext *s)
53{
54 struct SAPState *sap = s->priv_data;
55 if (sap->sdp_ctx)
56 avformat_close_input(&sap->sdp_ctx);
57 if (sap->ann_fd)
58 ffurl_close(sap->ann_fd);
59 av_freep(&sap->sdp);
60 ff_network_close();
61 return 0;
62}
63
64static int sap_read_header(AVFormatContext *s)
65{
66 struct SAPState *sap = s->priv_data;
67 char host[1024], path[1024], url[1024];
68 uint8_t recvbuf[RTP_MAX_PACKET_LENGTH];
69 int port;
70 int ret, i;
71 AVInputFormat* infmt;
72
73 if (!ff_network_init())
74 return AVERROR(EIO);
75
76 av_url_split(NULL, 0, NULL, 0, host, sizeof(host), &port,
77 path, sizeof(path), s->filename);
78 if (port < 0)
79 port = 9875;
80
81 if (!host[0]) {
82 /* Listen for announcements on sap.mcast.net if no host was specified */
83 av_strlcpy(host, "224.2.127.254", sizeof(host));
84 }
85
86 ff_url_join(url, sizeof(url), "udp", NULL, host, port, "?localport=%d",
87 port);
88 ret = ffurl_open_whitelist(&sap->ann_fd, url, AVIO_FLAG_READ,
89 &s->interrupt_callback, NULL,
90 s->protocol_whitelist, s->protocol_blacklist, NULL);
91 if (ret)
92 goto fail;
93
94 while (1) {
95 int addr_type, auth_len;
96 int pos;
97
98 ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf) - 1);
99 if (ret == AVERROR(EAGAIN))
100 continue;
101 if (ret < 0)
102 goto fail;
103 recvbuf[ret] = '\0'; /* Null terminate for easier parsing */
104 if (ret < 8) {
105 av_log(s, AV_LOG_WARNING, "Received too short packet\n");
106 continue;
107 }
108
109 if ((recvbuf[0] & 0xe0) != 0x20) {
110 av_log(s, AV_LOG_WARNING, "Unsupported SAP version packet "
111 "received\n");
112 continue;
113 }
114
115 if (recvbuf[0] & 0x04) {
116 av_log(s, AV_LOG_WARNING, "Received stream deletion "
117 "announcement\n");
118 continue;
119 }
120 addr_type = recvbuf[0] & 0x10;
121 auth_len = recvbuf[1];
122 sap->hash = AV_RB16(&recvbuf[2]);
123 pos = 4;
124 if (addr_type)
125 pos += 16; /* IPv6 */
126 else
127 pos += 4; /* IPv4 */
128 pos += auth_len * 4;
129 if (pos + 4 >= ret) {
130 av_log(s, AV_LOG_WARNING, "Received too short packet\n");
131 continue;
132 }
133#define MIME "application/sdp"
134 if (strcmp(&recvbuf[pos], MIME) == 0) {
135 pos += strlen(MIME) + 1;
136 } else if (strncmp(&recvbuf[pos], "v=0\r\n", 5) == 0) {
137 // Direct SDP without a mime type
138 } else {
139 av_log(s, AV_LOG_WARNING, "Unsupported mime type %s\n",
140 &recvbuf[pos]);
141 continue;
142 }
143
144 sap->sdp = av_strdup(&recvbuf[pos]);
145 break;
146 }
147
148 av_log(s, AV_LOG_VERBOSE, "SDP:\n%s\n", sap->sdp);
149 ffio_init_context(&sap->sdp_pb, sap->sdp, strlen(sap->sdp), 0, NULL, NULL,
150 NULL, NULL);
151
152 infmt = av_find_input_format("sdp");
153 if (!infmt)
154 goto fail;
155 sap->sdp_ctx = avformat_alloc_context();
156 if (!sap->sdp_ctx) {
157 ret = AVERROR(ENOMEM);
158 goto fail;
159 }
160 sap->sdp_ctx->max_delay = s->max_delay;
161 sap->sdp_ctx->pb = &sap->sdp_pb;
162 sap->sdp_ctx->interrupt_callback = s->interrupt_callback;
163
164 if ((ret = ff_copy_whiteblacklists(sap->sdp_ctx, s)) < 0)
165 goto fail;
166
167 ret = avformat_open_input(&sap->sdp_ctx, "temp.sdp", infmt, NULL);
168 if (ret < 0)
169 goto fail;
170 if (sap->sdp_ctx->ctx_flags & AVFMTCTX_NOHEADER)
171 s->ctx_flags |= AVFMTCTX_NOHEADER;
172 for (i = 0; i < sap->sdp_ctx->nb_streams; i++) {
173 AVStream *st = avformat_new_stream(s, NULL);
174 if (!st) {
175 ret = AVERROR(ENOMEM);
176 goto fail;
177 }
178 st->id = i;
179 avcodec_parameters_copy(st->codecpar, sap->sdp_ctx->streams[i]->codecpar);
180 st->time_base = sap->sdp_ctx->streams[i]->time_base;
181 }
182
183 return 0;
184
185fail:
186 sap_read_close(s);
187 return ret;
188}
189
190static int sap_fetch_packet(AVFormatContext *s, AVPacket *pkt)
191{
192 struct SAPState *sap = s->priv_data;
193 int fd = ffurl_get_file_handle(sap->ann_fd);
194 int n, ret;
195 struct pollfd p = {fd, POLLIN, 0};
196 uint8_t recvbuf[RTP_MAX_PACKET_LENGTH];
197
198 if (sap->eof)
199 return AVERROR_EOF;
200
201 while (1) {
202 n = poll(&p, 1, 0);
203 if (n <= 0 || !(p.revents & POLLIN))
204 break;
205 ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf));
206 if (ret >= 8) {
207 uint16_t hash = AV_RB16(&recvbuf[2]);
208 /* Should ideally check the source IP address, too */
209 if (recvbuf[0] & 0x04 && hash == sap->hash) {
210 /* Stream deletion */
211 sap->eof = 1;
212 return AVERROR_EOF;
213 }
214 }
215 }
216 ret = av_read_frame(sap->sdp_ctx, pkt);
217 if (ret < 0)
218 return ret;
219 if (s->ctx_flags & AVFMTCTX_NOHEADER) {
220 while (sap->sdp_ctx->nb_streams > s->nb_streams) {
221 int i = s->nb_streams;
222 AVStream *st = avformat_new_stream(s, NULL);
223 if (!st) {
224 av_packet_unref(pkt);
225 return AVERROR(ENOMEM);
226 }
227 st->id = i;
228 avcodec_parameters_copy(st->codecpar, sap->sdp_ctx->streams[i]->codecpar);
229 st->time_base = sap->sdp_ctx->streams[i]->time_base;
230 }
231 }
232 return ret;
233}
234
235AVInputFormat ff_sap_demuxer = {
236 .name = "sap",
237 .long_name = NULL_IF_CONFIG_SMALL("SAP input"),
238 .priv_data_size = sizeof(struct SAPState),
239 .read_probe = sap_probe,
240 .read_header = sap_read_header,
241 .read_packet = sap_fetch_packet,
242 .read_close = sap_read_close,
243 .flags = AVFMT_NOFILE,
244};
245
generated by cgit at 2024-05-17 06:56:34 (GMT)