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  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 FFmpeg.
  8.  *
  9.  * FFmpeg 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.  * FFmpeg 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 FFmpeg; 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 {
  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, const 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. };
  630.