libavformat/mmst.c

   1 /*
   2  * MMS protocol over TCP
   3  * Copyright (c) 2006,2007 Ryan Martell
   4  * Copyright (c) 2007 Björn Axelsson
   5  * Copyright (c) 2010 Zhentan Feng <spyfeng at gmail dot com>
   6  *
   7  * This file is part of Libav.
   8  *
   9  * Libav is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * Libav is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with Libav; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 /* References
  25  * MMS protocol specification:
  26  *  [1]http://msdn.microsoft.com/en-us/library/cc234711(PROT.10).aspx
  27  * ASF specification. Revision 01.20.03.
  28  *  [2]http://msdn.microsoft.com/en-us/library/bb643323.aspx
  29  */
  30
  31 #include "avformat.h"
  32 #include "mms.h"
  33 #include "internal.h"
  34 #include "avio_internal.h"
  35 #include "libavutil/intreadwrite.h"
  36 #include "libavcodec/bytestream.h"
  37 #include "network.h"
  38 #include "url.h"
  39
  40 #define LOCAL_ADDRESS 0xc0a80081    // FIXME get and use correct local ip address.
  41 #define LOCAL_PORT    1037          // as above.
  42 /** Client to server packet types. */
  43 typedef enum {
  44     CS_PKT_INITIAL                  = 0x01,
  45     CS_PKT_PROTOCOL_SELECT          = 0x02,
  46     CS_PKT_MEDIA_FILE_REQUEST       = 0x05,
  47     CS_PKT_START_FROM_PKT_ID        = 0x07,
  48     CS_PKT_STREAM_PAUSE             = 0x09,
  49     CS_PKT_STREAM_CLOSE             = 0x0d,
  50     CS_PKT_MEDIA_HEADER_REQUEST     = 0x15,
  51     CS_PKT_TIMING_DATA_REQUEST      = 0x18,
  52     CS_PKT_USER_PASSWORD            = 0x1a,
  53     CS_PKT_KEEPALIVE                = 0x1b,
  54     CS_PKT_STREAM_ID_REQUEST        = 0x33,
  55 } MMSCSPacketType;
  56
  57 /** Server to client packet types. */
  58 typedef enum {
  59     /** Control packets. */
  60     /*@{*/
  61     SC_PKT_CLIENT_ACCEPTED          = 0x01,
  62     SC_PKT_PROTOCOL_ACCEPTED        = 0x02,
  63     SC_PKT_PROTOCOL_FAILED          = 0x03,
  64     SC_PKT_MEDIA_PKT_FOLLOWS        = 0x05,
  65     SC_PKT_MEDIA_FILE_DETAILS       = 0x06,
  66     SC_PKT_HEADER_REQUEST_ACCEPTED  = 0x11,
  67     SC_PKT_TIMING_TEST_REPLY        = 0x15,
  68     SC_PKT_PASSWORD_REQUIRED        = 0x1a,
  69     SC_PKT_KEEPALIVE                = 0x1b,
  70     SC_PKT_STREAM_STOPPED           = 0x1e,
  71     SC_PKT_STREAM_CHANGING          = 0x20,
  72     SC_PKT_STREAM_ID_ACCEPTED       = 0x21,
  73     /*@}*/
  74
  75     /** Pseudo packets. */
  76     /*@{*/
  77     SC_PKT_CANCEL                   = -1,
  78     SC_PKT_NO_DATA                  = -2,
  79     /*@}*/
  80
  81     /** Data packets. */
  82     /*@{*/
  83     SC_PKT_ASF_HEADER               = 0x010000,// make it bigger than 0xFF in case of
  84     SC_PKT_ASF_MEDIA                = 0x010001,// receiving false data packets.
  85     /*@}*/
  86 } MMSSCPacketType;
  87
  88 typedef struct MMSTContext {
  89     MMSContext  mms;
  90     int outgoing_packet_seq;             ///< Outgoing packet sequence number.
  91     char path[256];                      ///< Path of the resource being asked for.
  92     char host[128];                      ///< Host of the resources.
  93     int incoming_packet_seq;             ///< Incoming packet sequence number.
  94     int incoming_flags;                  ///< Incoming packet flags.
  95     int packet_id;                       ///< Identifier for packets in the current stream.
  96     unsigned int header_packet_id;       ///< default is 2.
  97 } MMSTContext;
  98
  99 /** Create MMST command packet header */
 100 static void start_command_packet(MMSTContext *mmst, MMSCSPacketType packet_type)
 101 {
 102     MMSContext *mms    = &mmst->mms;
 103     mms->write_out_ptr = mms->out_buffer;
 104
 105     bytestream_put_le32(&mms->write_out_ptr, 1); // start sequence
 106     bytestream_put_le32(&mms->write_out_ptr, 0xb00bface);
 107     bytestream_put_le32(&mms->write_out_ptr, 0); // Length starts from after the protocol type bytes
 108     bytestream_put_le32(&mms->write_out_ptr, MKTAG('M','M','S',' '));
 109     bytestream_put_le32(&mms->write_out_ptr, 0);
 110     bytestream_put_le32(&mms->write_out_ptr, mmst->outgoing_packet_seq++);
 111     bytestream_put_le64(&mms->write_out_ptr, 0); // timestamp
 112     bytestream_put_le32(&mms->write_out_ptr, 0);
 113     bytestream_put_le16(&mms->write_out_ptr, packet_type);
 114     bytestream_put_le16(&mms->write_out_ptr, 3); // direction to server
 115 }
 116
 117 /** Add prefixes to MMST command packet. */
 118 static void insert_command_prefixes(MMSContext *mms,
 119         uint32_t prefix1, uint32_t prefix2)
 120 {
 121     bytestream_put_le32(&mms->write_out_ptr, prefix1); // first prefix
 122     bytestream_put_le32(&mms->write_out_ptr, prefix2); // second prefix
 123 }
 124
 125 /** Send a prepared MMST command packet. */
 126 static int send_command_packet(MMSTContext *mmst)
 127 {
 128     MMSContext *mms  = &mmst->mms;
 129     int len= mms->write_out_ptr - mms->out_buffer;
 130     int exact_length = FFALIGN(len, 8);
 131     int first_length= exact_length - 16;
 132     int len8= first_length/8;
 133     int write_result;
 134
 135     // update packet length fields.
 136     AV_WL32(mms->out_buffer + 8, first_length);
 137     AV_WL32(mms->out_buffer + 16, len8);
 138     AV_WL32(mms->out_buffer + 32, len8-2);
 139     memset(mms->write_out_ptr, 0, exact_length - len);
 140
 141     // write it out.
 142     write_result= ffurl_write(mms->mms_hd, mms->out_buffer, exact_length);
 143     if(write_result != exact_length) {
 144         av_log(NULL, AV_LOG_ERROR,
 145                "Failed to write data of length %d: %d (%s)\n",
 146                exact_length, write_result,
 147                write_result < 0 ? strerror(AVUNERROR(write_result)) :
 148                    "The server closed the connection");
 149         return AVERROR(EIO);
 150     }
 151
 152     return 0;
 153 }
 154
 155 static void mms_put_utf16(MMSContext *mms, uint8_t *src)
 156 {
 157     AVIOContext bic;
 158     int size = mms->write_out_ptr - mms->out_buffer;
 159     int len;
 160     ffio_init_context(&bic, mms->write_out_ptr,
 161             sizeof(mms->out_buffer) - size, 1, NULL, NULL, NULL, NULL);
 162
 163     len = avio_put_str16le(&bic, src);
 164     mms->write_out_ptr += len;
 165 }
 166
 167 static int send_time_test_data(MMSTContext *mmst)
 168 {
 169     start_command_packet(mmst, CS_PKT_TIMING_DATA_REQUEST);
 170     insert_command_prefixes(&mmst->mms, 0x00f0f0f0, 0x0004000b);
 171     return send_command_packet(mmst);
 172 }
 173
 174 static int send_protocol_select(MMSTContext *mmst)
 175 {
 176     char data_string[256];
 177     MMSContext *mms = &mmst->mms;
 178
 179     start_command_packet(mmst, CS_PKT_PROTOCOL_SELECT);
 180     insert_command_prefixes(mms, 0, 0xffffffff);
 181     bytestream_put_le32(&mms->write_out_ptr, 0);          // maxFunnelBytes
 182     bytestream_put_le32(&mms->write_out_ptr, 0x00989680); // maxbitRate
 183     bytestream_put_le32(&mms->write_out_ptr, 2);          // funnelMode
 184     snprintf(data_string, sizeof(data_string), "\\\\%d.%d.%d.%d\\%s\\%d",
 185             (LOCAL_ADDRESS>>24)&0xff,
 186             (LOCAL_ADDRESS>>16)&0xff,
 187             (LOCAL_ADDRESS>>8)&0xff,
 188             LOCAL_ADDRESS&0xff,
 189             "TCP",                                        // or UDP
 190             LOCAL_PORT);
 191
 192     mms_put_utf16(mms, data_string);
 193     return send_command_packet(mmst);
 194 }
 195
 196 static int send_media_file_request(MMSTContext *mmst)
 197 {
 198     MMSContext *mms = &mmst->mms;
 199     start_command_packet(mmst, CS_PKT_MEDIA_FILE_REQUEST);
 200     insert_command_prefixes(mms, 1, 0xffffffff);
 201     bytestream_put_le32(&mms->write_out_ptr, 0);
 202     bytestream_put_le32(&mms->write_out_ptr, 0);
 203     mms_put_utf16(mms, mmst->path + 1); // +1 for skip "/"
 204
 205     return send_command_packet(mmst);
 206 }
 207
 208 static void handle_packet_stream_changing_type(MMSTContext *mmst)
 209 {
 210     MMSContext *mms = &mmst->mms;
 211     av_dlog(NULL, "Stream changing!\n");
 212
 213     // 40 is the packet header size, 7 is the prefix size.
 214     mmst->header_packet_id= AV_RL32(mms->in_buffer + 40 + 7);
 215     av_dlog(NULL, "Changed header prefix to 0x%x", mmst->header_packet_id);
 216 }
 217
 218 static int send_keepalive_packet(MMSTContext *mmst)
 219 {
 220     // respond to a keepalive with a keepalive...
 221     start_command_packet(mmst, CS_PKT_KEEPALIVE);
 222     insert_command_prefixes(&mmst->mms, 1, 0x100FFFF);
 223     return send_command_packet(mmst);
 224 }
 225
 226 /** Pad media packets smaller than max_packet_size and/or adjust read position
 227   * after a seek. */
 228 static void pad_media_packet(MMSContext *mms)
 229 {
 230     if(mms->remaining_in_len<mms->asf_packet_len) {
 231         int padding_size = mms->asf_packet_len - mms->remaining_in_len;
 232         memset(mms->in_buffer + mms->remaining_in_len, 0, padding_size);
 233         mms->remaining_in_len += padding_size;
 234     }
 235 }
 236
 237 /** Read incoming MMST media, header or command packet. */
 238 static MMSSCPacketType get_tcp_server_response(MMSTContext *mmst)
 239 {
 240     int read_result;
 241     MMSSCPacketType packet_type= -1;
 242     MMSContext *mms = &mmst->mms;
 243     for(;;) {
 244         read_result = ffurl_read_complete(mms->mms_hd, mms->in_buffer, 8);
 245         if (read_result != 8) {
 246             if(read_result < 0) {
 247                 av_log(NULL, AV_LOG_ERROR,
 248                        "Error reading packet header: %d (%s)\n",
 249                        read_result, strerror(AVUNERROR(read_result)));
 250                 packet_type = SC_PKT_CANCEL;
 251             } else {
 252                 av_log(NULL, AV_LOG_ERROR,
 253                        "The server closed the connection\n");
 254                 packet_type = SC_PKT_NO_DATA;
 255             }
 256             return packet_type;
 257         }
 258
 259         // handle command packet.
 260         if(AV_RL32(mms->in_buffer + 4)==0xb00bface) {
 261             int length_remaining, hr;
 262
 263             mmst->incoming_flags= mms->in_buffer[3];
 264             read_result= ffurl_read_complete(mms->mms_hd, mms->in_buffer+8, 4);
 265             if(read_result != 4) {
 266                 av_log(NULL, AV_LOG_ERROR,
 267                        "Reading command packet length failed: %d (%s)\n",
 268                        read_result,
 269                        read_result < 0 ? strerror(AVUNERROR(read_result)) :
 270                            "The server closed the connection");
 271                 return read_result < 0 ? read_result : AVERROR(EIO);
 272             }
 273
 274             length_remaining= AV_RL32(mms->in_buffer+8) + 4;
 275             av_dlog(NULL, "Length remaining is %d\n", length_remaining);
 276             // read the rest of the packet.
 277             if (length_remaining < 0
 278                 || length_remaining > sizeof(mms->in_buffer) - 12) {
 279                 av_log(NULL, AV_LOG_ERROR,
 280                        "Incoming packet length %d exceeds bufsize %zu\n",
 281                        length_remaining, sizeof(mms->in_buffer) - 12);
 282                 return AVERROR_INVALIDDATA;
 283             }
 284             read_result = ffurl_read_complete(mms->mms_hd, mms->in_buffer + 12,
 285                                             length_remaining) ;
 286             if (read_result != length_remaining) {
 287                 av_log(NULL, AV_LOG_ERROR,
 288                        "Reading pkt data (length=%d) failed: %d (%s)\n",
 289                        length_remaining, read_result,
 290                        read_result < 0 ? strerror(AVUNERROR(read_result)) :
 291                            "The server closed the connection");
 292                 return read_result < 0 ? read_result : AVERROR(EIO);
 293             }
 294             packet_type= AV_RL16(mms->in_buffer+36);
 295             if (read_result >= 44 && (hr = AV_RL32(mms->in_buffer + 40))) {
 296                 av_log(NULL, AV_LOG_ERROR,
 297                        "Server sent a message with packet type 0x%x and error status code 0x%08x\n", packet_type, hr);
 298                 return AVERROR(EINVAL);
 299             }
 300         } else {
 301             int length_remaining;
 302             int packet_id_type;
 303             int tmp;
 304
 305             // note we cache the first 8 bytes,
 306             // then fill up the buffer with the others
 307             tmp                       = AV_RL16(mms->in_buffer + 6);
 308             length_remaining          = (tmp - 8) & 0xffff;
 309             mmst->incoming_packet_seq = AV_RL32(mms->in_buffer);
 310             packet_id_type            = mms->in_buffer[4];
 311             mmst->incoming_flags      = mms->in_buffer[5];
 312
 313             if (length_remaining < 0
 314                 || length_remaining > sizeof(mms->in_buffer) - 8) {
 315                 av_log(NULL, AV_LOG_ERROR,
 316                        "Data length %d is invalid or too large (max=%zu)\n",
 317                        length_remaining, sizeof(mms->in_buffer));
 318                 return AVERROR_INVALIDDATA;
 319             }
 320             mms->remaining_in_len    = length_remaining;
 321             mms->read_in_ptr         = mms->in_buffer;
 322             read_result= ffurl_read_complete(mms->mms_hd, mms->in_buffer, length_remaining);
 323             if(read_result != length_remaining) {
 324                 av_log(NULL, AV_LOG_ERROR,
 325                        "Failed to read packet data of size %d: %d (%s)\n",
 326                        length_remaining, read_result,
 327                        read_result < 0 ? strerror(AVUNERROR(read_result)) :
 328                            "The server closed the connection");
 329                 return read_result < 0 ? read_result : AVERROR(EIO);
 330             }
 331
 332             // if we successfully read everything.
 333             if(packet_id_type == mmst->header_packet_id) {
 334                 int err;
 335                 packet_type = SC_PKT_ASF_HEADER;
 336                 // Store the asf header
 337                 if(!mms->header_parsed) {
 338                     if ((err = av_reallocp(&mms->asf_header,
 339                                            mms->asf_header_size +
 340                                            mms->remaining_in_len)) < 0) {
 341                         mms->asf_header_size = 0;
 342                         return err;
 343                     }
 344                     memcpy(mms->asf_header + mms->asf_header_size,
 345                            mms->read_in_ptr, mms->remaining_in_len);
 346                     mms->asf_header_size += mms->remaining_in_len;
 347                 }
 348                 // 0x04 means asf header is sent in multiple packets.
 349                 if (mmst->incoming_flags == 0x04)
 350                     continue;
 351             } else if(packet_id_type == mmst->packet_id) {
 352                 packet_type = SC_PKT_ASF_MEDIA;
 353             } else {
 354                 av_dlog(NULL, "packet id type %d is old.", packet_id_type);
 355                 continue;
 356             }
 357         }
 358
 359         // preprocess some packet type
 360         if(packet_type == SC_PKT_KEEPALIVE) {
 361             send_keepalive_packet(mmst);
 362             continue;
 363         } else if(packet_type == SC_PKT_STREAM_CHANGING) {
 364             handle_packet_stream_changing_type(mmst);
 365         } else if(packet_type == SC_PKT_ASF_MEDIA) {
 366             pad_media_packet(mms);
 367         }
 368         return packet_type;
 369     }
 370 }
 371
 372 static int mms_safe_send_recv(MMSTContext *mmst,
 373                               int (*send_fun)(MMSTContext *mmst),
 374                               const MMSSCPacketType expect_type)
 375 {
 376     MMSSCPacketType type;
 377     if(send_fun) {
 378         int ret = send_fun(mmst);
 379         if (ret < 0) {
 380             av_dlog(NULL, "Send Packet error before expecting recv packet %d\n", expect_type);
 381             return ret;
 382         }
 383     }
 384
 385     if ((type = get_tcp_server_response(mmst)) != expect_type) {
 386         av_log(NULL, AV_LOG_ERROR,
 387                "Corrupt stream (unexpected packet type 0x%x, expected 0x%x)\n",
 388                type, expect_type);
 389         return AVERROR_INVALIDDATA;
 390     } else {
 391         return 0;
 392     }
 393 }
 394
 395 static int send_media_header_request(MMSTContext *mmst)
 396 {
 397     MMSContext *mms = &mmst->mms;
 398     start_command_packet(mmst, CS_PKT_MEDIA_HEADER_REQUEST);
 399     insert_command_prefixes(mms, 1, 0);
 400     bytestream_put_le32(&mms->write_out_ptr, 0);
 401     bytestream_put_le32(&mms->write_out_ptr, 0x00800000);
 402     bytestream_put_le32(&mms->write_out_ptr, 0xffffffff);
 403     bytestream_put_le32(&mms->write_out_ptr, 0);
 404     bytestream_put_le32(&mms->write_out_ptr, 0);
 405     bytestream_put_le32(&mms->write_out_ptr, 0);
 406
 407     // the media preroll value in milliseconds?
 408     bytestream_put_le32(&mms->write_out_ptr, 0);
 409     bytestream_put_le32(&mms->write_out_ptr, 0x40AC2000);
 410     bytestream_put_le32(&mms->write_out_ptr, 2);
 411     bytestream_put_le32(&mms->write_out_ptr, 0);
 412
 413     return send_command_packet(mmst);
 414 }
 415
 416 /** Send the initial handshake. */
 417 static int send_startup_packet(MMSTContext *mmst)
 418 {
 419     char data_string[256];
 420     MMSContext *mms = &mmst->mms;
 421     // SubscriberName is defined in MS specification linked below.
 422     // The guid value can be any valid value.
 423     // http://download.microsoft.com/
 424     // download/9/5/E/95EF66AF-9026-4BB0-A41D-A4F81802D92C/%5BMS-WMSP%5D.pdf
 425     snprintf(data_string, sizeof(data_string),
 426             "NSPlayer/7.0.0.1956; {%s}; Host: %s",
 427             "7E667F5D-A661-495E-A512-F55686DDA178", mmst->host);
 428
 429     start_command_packet(mmst, CS_PKT_INITIAL);
 430     insert_command_prefixes(mms, 0, 0x0004000b);
 431     bytestream_put_le32(&mms->write_out_ptr, 0x0003001c);
 432     mms_put_utf16(mms, data_string);
 433     return send_command_packet(mmst);
 434 }
 435
 436 /** Send MMST stream selection command based on the AVStream->discard values. */
 437 static int send_stream_selection_request(MMSTContext *mmst)
 438 {
 439     int i;
 440     MMSContext *mms = &mmst->mms;
 441     //  send the streams we want back...
 442     start_command_packet(mmst, CS_PKT_STREAM_ID_REQUEST);
 443     bytestream_put_le32(&mms->write_out_ptr, mms->stream_num);         // stream nums
 444     for(i= 0; i<mms->stream_num; i++) {
 445         bytestream_put_le16(&mms->write_out_ptr, 0xffff);              // flags
 446         bytestream_put_le16(&mms->write_out_ptr, mms->streams[i].id);  // stream id
 447         bytestream_put_le16(&mms->write_out_ptr, 0);                   // selection
 448     }
 449     return send_command_packet(mmst);
 450 }
 451
 452 static int send_close_packet(MMSTContext *mmst)
 453 {
 454     start_command_packet(mmst, CS_PKT_STREAM_CLOSE);
 455     insert_command_prefixes(&mmst->mms, 1, 1);
 456
 457     return send_command_packet(mmst);
 458 }
 459
 460 /** Close the MMSH/MMST connection */
 461 static int mms_close(URLContext *h)
 462 {
 463     MMSTContext *mmst = (MMSTContext *)h->priv_data;
 464     MMSContext *mms   = &mmst->mms;
 465     if(mms->mms_hd) {
 466         send_close_packet(mmst);
 467         ffurl_close(mms->mms_hd);
 468     }
 469
 470     /* free all separately allocated pointers in mms */
 471     av_free(mms->streams);
 472     av_free(mms->asf_header);
 473
 474     return 0;
 475 }
 476
 477 static int send_media_packet_request(MMSTContext *mmst)
 478 {
 479     MMSContext *mms = &mmst->mms;
 480     start_command_packet(mmst, CS_PKT_START_FROM_PKT_ID);
 481     insert_command_prefixes(mms, 1, 0x0001FFFF);
 482     bytestream_put_le64(&mms->write_out_ptr, 0);          // seek timestamp
 483     bytestream_put_le32(&mms->write_out_ptr, 0xffffffff); // unknown
 484     bytestream_put_le32(&mms->write_out_ptr, 0xffffffff); // packet offset
 485     bytestream_put_byte(&mms->write_out_ptr, 0xff);       // max stream time limit
 486     bytestream_put_byte(&mms->write_out_ptr, 0xff);       // max stream time limit
 487     bytestream_put_byte(&mms->write_out_ptr, 0xff);       // max stream time limit
 488     bytestream_put_byte(&mms->write_out_ptr, 0x00);       // stream time limit flag
 489
 490     mmst->packet_id++;                                     // new packet_id
 491     bytestream_put_le32(&mms->write_out_ptr, mmst->packet_id);
 492     return send_command_packet(mmst);
 493 }
 494
 495
 496 static void clear_stream_buffers(MMSContext *mms)
 497 {
 498     mms->remaining_in_len = 0;
 499     mms->read_in_ptr      = mms->in_buffer;
 500 }
 501
 502 static int mms_open(URLContext *h, const char *uri, int flags)
 503 {
 504     MMSTContext *mmst = h->priv_data;
 505     MMSContext *mms;
 506     int port, err;
 507     char tcpname[256];
 508
 509     h->is_streamed = 1;
 510     mms = &mmst->mms;
 511
 512     // only for MMS over TCP, so set proto = NULL
 513     av_url_split(NULL, 0, NULL, 0,
 514             mmst->host, sizeof(mmst->host), &port, mmst->path,
 515             sizeof(mmst->path), uri);
 516
 517     if(port<0)
 518         port = 1755; // defaut mms protocol port
 519
 520     // establish tcp connection.
 521     ff_url_join(tcpname, sizeof(tcpname), "tcp", NULL, mmst->host, port, NULL);
 522     err = ffurl_open(&mms->mms_hd, tcpname, AVIO_FLAG_READ_WRITE,
 523                      &h->interrupt_callback, NULL);
 524     if (err)
 525         goto fail;
 526
 527     mmst->packet_id        = 3;          // default, initial value.
 528     mmst->header_packet_id = 2;          // default, initial value.
 529     err = mms_safe_send_recv(mmst, send_startup_packet, SC_PKT_CLIENT_ACCEPTED);
 530     if (err)
 531         goto fail;
 532     err = mms_safe_send_recv(mmst, send_time_test_data, SC_PKT_TIMING_TEST_REPLY);
 533     if (err)
 534         goto fail;
 535     err = mms_safe_send_recv(mmst, send_protocol_select, SC_PKT_PROTOCOL_ACCEPTED);
 536     if (err)
 537         goto fail;
 538     err = mms_safe_send_recv(mmst, send_media_file_request, SC_PKT_MEDIA_FILE_DETAILS);
 539     if (err)
 540         goto fail;
 541     err = mms_safe_send_recv(mmst, send_media_header_request, SC_PKT_HEADER_REQUEST_ACCEPTED);
 542     if (err)
 543         goto fail;
 544     err = mms_safe_send_recv(mmst, NULL, SC_PKT_ASF_HEADER);
 545     if (err)
 546         goto fail;
 547     if((mmst->incoming_flags != 0X08) && (mmst->incoming_flags != 0X0C)) {
 548         av_log(NULL, AV_LOG_ERROR,
 549                "The server does not support MMST (try MMSH or RTSP)\n");
 550         err = AVERROR(EINVAL);
 551         goto fail;
 552     }
 553     err = ff_mms_asf_header_parser(mms);
 554     if (err) {
 555         av_dlog(NULL, "asf header parsed failed!\n");
 556         goto fail;
 557     }
 558     mms->header_parsed = 1;
 559
 560     if (!mms->asf_packet_len || !mms->stream_num)
 561         goto fail;
 562
 563     clear_stream_buffers(mms);
 564     err = mms_safe_send_recv(mmst, send_stream_selection_request, SC_PKT_STREAM_ID_ACCEPTED);
 565     if (err)
 566         goto fail;
 567     // send media packet request
 568     err = mms_safe_send_recv(mmst, send_media_packet_request, SC_PKT_MEDIA_PKT_FOLLOWS);
 569     if (err) {
 570         goto fail;
 571     }
 572     av_dlog(NULL, "Leaving open (success)\n");
 573     return 0;
 574 fail:
 575     mms_close(h);
 576     av_dlog(NULL, "Leaving open (failure: %d)\n", err);
 577     return err;
 578 }
 579
 580 /** Read ASF data through the protocol. */
 581 static int mms_read(URLContext *h, uint8_t *buf, int size)
 582 {
 583     /* TODO: see tcp.c:tcp_read() about a possible timeout scheme */
 584     MMSTContext *mmst = h->priv_data;
 585     MMSContext *mms   = &mmst->mms;
 586     int result = 0;
 587
 588     do {
 589         if(mms->asf_header_read_size < mms->asf_header_size) {
 590             /* Read from ASF header buffer */
 591             result = ff_mms_read_header(mms, buf, size);
 592         } else if(mms->remaining_in_len) {
 593             /* Read remaining packet data to buffer.
 594              * the result can not be zero because remaining_in_len is positive.*/
 595             result = ff_mms_read_data(mms, buf, size);
 596         } else {
 597             /* Read from network */
 598             int err = mms_safe_send_recv(mmst, NULL, SC_PKT_ASF_MEDIA);
 599             if (err == 0) {
 600                 if(mms->remaining_in_len>mms->asf_packet_len) {
 601                     av_log(NULL, AV_LOG_ERROR,
 602                            "Incoming pktlen %d is larger than ASF pktsize %d\n",
 603                            mms->remaining_in_len, mms->asf_packet_len);
 604                     result= AVERROR(EIO);
 605                 } else {
 606                     // copy the data to the packet buffer.
 607                     result = ff_mms_read_data(mms, buf, size);
 608                     if (result == 0) {
 609                         av_dlog(NULL, "Read ASF media packet size is zero!\n");
 610                         break;
 611                     }
 612                 }
 613             } else {
 614                 av_dlog(NULL, "read packet error!\n");
 615                 break;
 616             }
 617         }
 618     } while(!result); // only return one packet.
 619     return result;
 620 }
 621
 622 URLProtocol ff_mmst_protocol = {
 623     .name           = "mmst",
 624     .url_open       = mms_open,
 625     .url_read       = mms_read,
 626     .url_close      = mms_close,
 627     .priv_data_size = sizeof(MMSTContext),
 628     .flags          = URL_PROTOCOL_FLAG_NETWORK,
 629 };