release/src/router/udpxy/rtp.h

   1 /* @(#) interface to RTP-protocol parsing functions for udpxy
   2  *
   3  * Copyright 2008-2011 Pavel V. Cherenkov (pcherenkov@gmail.com)
   4  *
   5  *  This file is part of udpxy.
   6  *
   7  *  udpxy is free software: you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License as published by
   9  *  the Free Software Foundation, either version 3 of the License, or
  10  *  (at your option) any later version.
  11  *
  12  *  udpxy 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
  15  *  GNU General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License
  18  *  along with udpxy.  If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #ifndef RTPH_UDPXY_021308
  22 #define RTPH_UDPXY_021308
  23
  24 #include <sys/types.h>
  25
  26 static const int    MPEG_TS_SIG = 0x47;
  27 static const size_t RTP_MIN_SIZE = 4;
  28 static const size_t RTP_HDR_SIZE = 12; /* RFC 3550 */
  29 static const int    RTP_VER2 = 0x02;
  30
  31 /* offset to header extension and extension length,
  32     * as per RFC 3550 5.3.1 */
  33 static const size_t XTLEN_OFFSET = 14;
  34 static const size_t XTSIZE = 4;
  35
  36 /* minimum length to determine size of an extended RTP header
  37  */
  38 #define RTP_XTHDRLEN (XTLEN_OFFSET + XTSIZE)
  39
  40 static const size_t CSRC_SIZE = 4;
  41
  42 /* MPEG payload-type constants - adopted from VLC 0.8.6 */
  43 #define P_MPGA      0x0E     /* MPEG audio */
  44 #define P_MPGV      0x20     /* MPEG video */
  45 #define P_MPGTS     0x21     /* MPEG TS    */
  46
  47 #ifdef __cplusplus
  48 extern "C" {
  49 #endif
  50
  51
  52 /* check if the buffer is an RTP packet
  53  *
  54  * @param buf       buffer to analyze
  55  * @param len       size of the buffer
  56  * @param is_rtp    variable to set to 1 if data is an RTP packet
  57  * @param log       log file
  58  *
  59  * @return 0 if there was no error, -1 otherwise
  60  */
  61 int RTP_check( const char* buf, const size_t len, int* is_rtp, FILE* log );
  62
  63
  64 /* process RTP package to retrieve the payload: set
  65  * pbuf to the start of the payload area; set len to
  66  * be equal payload's length
  67  *
  68  * @param pbuf      address of pointer to beginning of RTP packet
  69  * @param len       pointer to RTP packet's length
  70  * @param verify    verify that it is an RTP packet if != 0
  71  * @param log       log file
  72  *
  73  * @return 0 if there was no error, -1 otherwise;
  74  *         set pbuf to point to beginning of payload and len
  75  *         be payload size in bytes
  76  */
  77 int RTP_process( void** pbuf, size_t* len, int verify, FILE* log );
  78
  79
  80 /* verify if buffer contains an RTP packet, 0 otherwise
  81  *
  82  * @param buf       buffer to analyze
  83  * @param len       size of the buffer
  84  * @param log       error log
  85  *
  86  * @return 1 if buffer contains an RTP packet, 0 otherwise
  87  */
  88 int RTP_verify( const char* buf, const size_t len, FILE* log );
  89
  90
  91 /* calculate length of an RTP header
  92  *
  93  * @param buf       buffer to analyze
  94  * @param len       size of the buffer
  95  * @param hdrlen    pointer to header length variable
  96  * @param log       error log
  97  *
  98  * @return          0 if header length has been calculated,
  99  *                  ENOMEM if buffer is not big enough
 100  */
 101 int RTP_hdrlen( const char* buf, const size_t len, size_t* hdrlen,
 102                     FILE* log );
 103
 104 #ifdef __cplusplus
 105 }
 106 #endif
 107
 108 #endif /* RTPH_UDPXY_021308 */
 109
 110
 111 /* __EOF__ */
 112