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  1. /*
  2.  * Microsoft RTP/ASF support.
  3.  * Copyright (c) 2008 Ronald S. Bultje
  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. /**
  23.  * @file
  24.  * @brief Microsoft RTP/ASF support
  25.  * @author Ronald S. Bultje <rbultje@ronald.bitfreak.net>
  26.  */
  27.  
  28. #include "libavutil/avassert.h"
  29. #include "libavutil/base64.h"
  30. #include "libavutil/avstring.h"
  31. #include "libavutil/intreadwrite.h"
  32. #include "rtp.h"
  33. #include "rtpdec_formats.h"
  34. #include "rtsp.h"
  35. #include "asf.h"
  36. #include "avio_internal.h"
  37. #include "internal.h"
  38.  
  39. /**
  40.  * From MSDN 2.2.1.4, we learn that ASF data packets over RTP should not
  41.  * contain any padding. Unfortunately, the header min/max_pktsize are not
  42.  * updated (thus making min_pktsize invalid). Here, we "fix" these faulty
  43.  * min_pktsize values in the ASF file header.
  44.  * @return 0 on success, <0 on failure (currently -1).
  45.  */
  46. static int rtp_asf_fix_header(uint8_t *buf, int len)
  47. {
  48.     uint8_t *p = buf, *end = buf + len;
  49.  
  50.     if (len < sizeof(ff_asf_guid) * 2 + 22 ||
  51.         memcmp(p, ff_asf_header, sizeof(ff_asf_guid))) {
  52.         return -1;
  53.     }
  54.     p += sizeof(ff_asf_guid) + 14;
  55.     do {
  56.         uint64_t chunksize = AV_RL64(p + sizeof(ff_asf_guid));
  57.         int skip = 6 * 8 + 3 * 4 + sizeof(ff_asf_guid) * 2;
  58.         if (memcmp(p, ff_asf_file_header, sizeof(ff_asf_guid))) {
  59.             if (chunksize > end - p)
  60.                 return -1;
  61.             p += chunksize;
  62.             continue;
  63.         }
  64.  
  65.         if (end - p < 8 + skip)
  66.             break;
  67.         /* skip most of the file header, to min_pktsize */
  68.         p += skip;
  69.         if (AV_RL32(p) == AV_RL32(p + 4)) {
  70.             /* and set that to zero */
  71.             AV_WL32(p, 0);
  72.             return 0;
  73.         }
  74.         break;
  75.     } while (end - p >= sizeof(ff_asf_guid) + 8);
  76.  
  77.     return -1;
  78. }
  79.  
  80. /**
  81.  * The following code is basically a buffered AVIOContext,
  82.  * with the added benefit of returning -EAGAIN (instead of 0)
  83.  * on packet boundaries, such that the ASF demuxer can return
  84.  * safely and resume business at the next packet.
  85.  */
  86. static int packetizer_read(void *opaque, uint8_t *buf, int buf_size)
  87. {
  88.     return AVERROR(EAGAIN);
  89. }
  90.  
  91. static void init_packetizer(AVIOContext *pb, uint8_t *buf, int len)
  92. {
  93.     ffio_init_context(pb, buf, len, 0, NULL, packetizer_read, NULL, NULL);
  94.  
  95.     /* this "fills" the buffer with its current content */
  96.     pb->pos     = len;
  97.     pb->buf_end = buf + len;
  98. }
  99.  
  100. int ff_wms_parse_sdp_a_line(AVFormatContext *s, const char *p)
  101. {
  102.     int ret = 0;
  103.     if (av_strstart(p, "pgmpu:data:application/vnd.ms.wms-hdr.asfv1;base64,", &p)) {
  104.         AVIOContext pb;
  105.         RTSPState *rt = s->priv_data;
  106.         AVDictionary *opts = NULL;
  107.         int len = strlen(p) * 6 / 8;
  108.         char *buf = av_mallocz(len);
  109.         AVInputFormat *iformat;
  110.  
  111.         if (!buf)
  112.             return AVERROR(ENOMEM);
  113.         av_base64_decode(buf, p, len);
  114.  
  115.         if (rtp_asf_fix_header(buf, len) < 0)
  116.             av_log(s, AV_LOG_ERROR,
  117.                    "Failed to fix invalid RTSP-MS/ASF min_pktsize\n");
  118.         init_packetizer(&pb, buf, len);
  119.         if (rt->asf_ctx) {
  120.             avformat_close_input(&rt->asf_ctx);
  121.         }
  122.  
  123.         if (!(iformat = av_find_input_format("asf")))
  124.             return AVERROR_DEMUXER_NOT_FOUND;
  125.  
  126.         rt->asf_ctx = avformat_alloc_context();
  127.         if (!rt->asf_ctx) {
  128.             av_free(buf);
  129.             return AVERROR(ENOMEM);
  130.         }
  131.         rt->asf_ctx->pb      = &pb;
  132.         av_dict_set(&opts, "no_resync_search", "1", 0);
  133.  
  134.         if ((ret = ff_copy_whitelists(rt->asf_ctx, s)) < 0) {
  135.             av_dict_free(&opts);
  136.             return ret;
  137.         }
  138.  
  139.         ret = avformat_open_input(&rt->asf_ctx, "", iformat, &opts);
  140.         av_dict_free(&opts);
  141.         if (ret < 0) {
  142.             av_free(buf);
  143.             return ret;
  144.         }
  145.         av_dict_copy(&s->metadata, rt->asf_ctx->metadata, 0);
  146.         rt->asf_pb_pos = avio_tell(&pb);
  147.         av_free(buf);
  148.         rt->asf_ctx->pb = NULL;
  149.     }
  150.     return ret;
  151. }
  152.  
  153. static int asfrtp_parse_sdp_line(AVFormatContext *s, int stream_index,
  154.                                  PayloadContext *asf, const char *line)
  155. {
  156.     if (stream_index < 0)
  157.         return 0;
  158.     if (av_strstart(line, "stream:", &line)) {
  159.         RTSPState *rt = s->priv_data;
  160.  
  161.         s->streams[stream_index]->id = strtol(line, NULL, 10);
  162.  
  163.         if (rt->asf_ctx) {
  164.             int i;
  165.  
  166.             for (i = 0; i < rt->asf_ctx->nb_streams; i++) {
  167.                 if (s->streams[stream_index]->id == rt->asf_ctx->streams[i]->id) {
  168.                     *s->streams[stream_index]->codec =
  169.                         *rt->asf_ctx->streams[i]->codec;
  170.                     s->streams[stream_index]->need_parsing =
  171.                         rt->asf_ctx->streams[i]->need_parsing;
  172.                     rt->asf_ctx->streams[i]->codec->extradata_size = 0;
  173.                     rt->asf_ctx->streams[i]->codec->extradata = NULL;
  174.                     avpriv_set_pts_info(s->streams[stream_index], 32, 1, 1000);
  175.                 }
  176.            }
  177.         }
  178.     }
  179.  
  180.     return 0;
  181. }
  182.  
  183. struct PayloadContext {
  184.     AVIOContext *pktbuf, pb;
  185.     uint8_t *buf;
  186. };
  187.  
  188. /**
  189.  * @return 0 when a packet was written into /p pkt, and no more data is left;
  190.  *         1 when a packet was written into /p pkt, and more packets might be left;
  191.  *        <0 when not enough data was provided to return a full packet, or on error.
  192.  */
  193. static int asfrtp_parse_packet(AVFormatContext *s, PayloadContext *asf,
  194.                                AVStream *st, AVPacket *pkt,
  195.                                uint32_t *timestamp,
  196.                                const uint8_t *buf, int len, uint16_t seq,
  197.                                int flags)
  198. {
  199.     AVIOContext *pb = &asf->pb;
  200.     int res, mflags, len_off;
  201.     RTSPState *rt = s->priv_data;
  202.  
  203.     if (!rt->asf_ctx)
  204.         return -1;
  205.  
  206.     if (len > 0) {
  207.         int off, out_len = 0;
  208.  
  209.         if (len < 4)
  210.             return -1;
  211.  
  212.         av_freep(&asf->buf);
  213.  
  214.         ffio_init_context(pb, (uint8_t *)buf, len, 0, NULL, NULL, NULL, NULL);
  215.  
  216.         while (avio_tell(pb) + 4 < len) {
  217.             int start_off = avio_tell(pb);
  218.  
  219.             mflags = avio_r8(pb);
  220.             len_off = avio_rb24(pb);
  221.             if (mflags & 0x20)   /**< relative timestamp */
  222.                 avio_skip(pb, 4);
  223.             if (mflags & 0x10)   /**< has duration */
  224.                 avio_skip(pb, 4);
  225.             if (mflags & 0x8)    /**< has location ID */
  226.                 avio_skip(pb, 4);
  227.             off = avio_tell(pb);
  228.  
  229.             if (!(mflags & 0x40)) {
  230.                 /**
  231.                  * If 0x40 is not set, the len_off field specifies an offset
  232.                  * of this packet's payload data in the complete (reassembled)
  233.                  * ASF packet. This is used to spread one ASF packet over
  234.                  * multiple RTP packets.
  235.                  */
  236.                 if (asf->pktbuf && len_off != avio_tell(asf->pktbuf)) {
  237.                     ffio_free_dyn_buf(&asf->pktbuf);
  238.                 }
  239.                 if (!len_off && !asf->pktbuf &&
  240.                     (res = avio_open_dyn_buf(&asf->pktbuf)) < 0)
  241.                     return res;
  242.                 if (!asf->pktbuf)
  243.                     return AVERROR(EIO);
  244.  
  245.                 avio_write(asf->pktbuf, buf + off, len - off);
  246.                 avio_skip(pb, len - off);
  247.                 if (!(flags & RTP_FLAG_MARKER))
  248.                     return -1;
  249.                 out_len     = avio_close_dyn_buf(asf->pktbuf, &asf->buf);
  250.                 asf->pktbuf = NULL;
  251.             } else {
  252.                 /**
  253.                  * If 0x40 is set, the len_off field specifies the length of
  254.                  * the next ASF packet that can be read from this payload
  255.                  * data alone. This is commonly the same as the payload size,
  256.                  * but could be less in case of packet splitting (i.e.
  257.                  * multiple ASF packets in one RTP packet).
  258.                  */
  259.  
  260.                 int cur_len = start_off + len_off - off;
  261.                 int prev_len = out_len;
  262.                 out_len += cur_len;
  263.                 if (FFMIN(cur_len, len - off) < 0)
  264.                     return -1;
  265.                 if ((res = av_reallocp(&asf->buf, out_len)) < 0)
  266.                     return res;
  267.                 memcpy(asf->buf + prev_len, buf + off,
  268.                        FFMIN(cur_len, len - off));
  269.                 avio_skip(pb, cur_len);
  270.             }
  271.         }
  272.  
  273.         init_packetizer(pb, asf->buf, out_len);
  274.         pb->pos += rt->asf_pb_pos;
  275.         pb->eof_reached = 0;
  276.         rt->asf_ctx->pb = pb;
  277.     }
  278.  
  279.     for (;;) {
  280.         int i;
  281.  
  282.         res = ff_read_packet(rt->asf_ctx, pkt);
  283.         rt->asf_pb_pos = avio_tell(pb);
  284.         if (res != 0)
  285.             break;
  286.         for (i = 0; i < s->nb_streams; i++) {
  287.             if (s->streams[i]->id == rt->asf_ctx->streams[pkt->stream_index]->id) {
  288.                 pkt->stream_index = i;
  289.                 return 1; // FIXME: return 0 if last packet
  290.             }
  291.         }
  292.         av_free_packet(pkt);
  293.     }
  294.  
  295.     return res == 1 ? -1 : res;
  296. }
  297.  
  298. static void asfrtp_close_context(PayloadContext *asf)
  299. {
  300.     ffio_free_dyn_buf(&asf->pktbuf);
  301.     av_freep(&asf->buf);
  302. }
  303.  
  304. #define RTP_ASF_HANDLER(n, s, t) \
  305. RTPDynamicProtocolHandler ff_ms_rtp_ ## n ## _handler = { \
  306.     .enc_name         = s, \
  307.     .codec_type       = t, \
  308.     .codec_id         = AV_CODEC_ID_NONE, \
  309.     .priv_data_size   = sizeof(PayloadContext), \
  310.     .parse_sdp_a_line = asfrtp_parse_sdp_line, \
  311.     .close            = asfrtp_close_context, \
  312.     .parse_packet     = asfrtp_parse_packet,   \
  313. }
  314.  
  315. RTP_ASF_HANDLER(asf_pfv, "x-asf-pf",  AVMEDIA_TYPE_VIDEO);
  316. RTP_ASF_HANDLER(asf_pfa, "x-asf-pf",  AVMEDIA_TYPE_AUDIO);
  317.