SDPOPS Module

Daniel-Constantin Mierla

   <miconda@gmail.com>

Edited by

Daniel-Constantin Mierla

   <miconda@gmail.com>

   Copyright © 2011 asipto.com
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications

        3. Parameters
        4. Functions

              4.1. sdp_remove_codecs_by_id(list)
              4.2. sdp_remove_codecs_by_name(list)
              4.3. sdp_remove_line_by_prefix(string)
              4.4. sdp_keep_codecs_by_id(list [, mtype])
              4.5. sdp_keep_codecs_by_name(list [, mtype])
              4.6. sdp_with_media(type)
              4.7. sdp_remove_media(type)
              4.8. sdp_with_transport(type)
              4.9. sdp_remove_transport(type)
              4.10. sdp_with_codecs_by_id(list)
              4.11. sdp_with_codecs_by_name(list)
              4.12. sdp_print(level)
              4.13. sdp_get(avpvar)
              4.14. sdp_content()
              4.15. sdp_get_line_startswith(avpvar, string)

   List of Examples

   1.1. sdp_remove_codecs_by_id usage
   1.2. sdp_remove_codecs_by_name usage
   1.3. sdp_remove_line_by_prefix usage
   1.4. sdp_keep_codecs_by_id usage
   1.5. sdp_keep_codecs_by_name usage
   1.6. sdp_with_media usage
   1.7. sdp_remove_media usage
   1.8. sdp_with_transport usage
   1.9. sdp_remove_transport usage
   1.10. sdp_with_codecs_by_id usage
   1.11. sdp_with_codecs_by_name usage
   1.12. sdp_print usage
   1.13. sdp_get usage
   1.14. sdp_content usage
   1.15. sdp_get_line_startswith usage

Chapter 1. Admin Guide

   Table of Contents

   1. Overview
   2. Dependencies

        2.1. Kamailio Modules
        2.2. External Libraries or Applications

   3. Parameters
   4. Functions

        4.1. sdp_remove_codecs_by_id(list)
        4.2. sdp_remove_codecs_by_name(list)
        4.3. sdp_remove_line_by_prefix(string)
        4.4. sdp_keep_codecs_by_id(list [, mtype])
        4.5. sdp_keep_codecs_by_name(list [, mtype])
        4.6. sdp_with_media(type)
        4.7. sdp_remove_media(type)
        4.8. sdp_with_transport(type)
        4.9. sdp_remove_transport(type)
        4.10. sdp_with_codecs_by_id(list)
        4.11. sdp_with_codecs_by_name(list)
        4.12. sdp_print(level)
        4.13. sdp_get(avpvar)
        4.14. sdp_content()
        4.15. sdp_get_line_startswith(avpvar, string)

1. Overview

   This module provides functions for checking and managing the SDP
   payloads of SIP messages.

   Examples of functions this module offers: remove codecs from SDP, check
   the media stream types and return attributes of SDP document. For the
   full list of the features provided by this module and the
   implementation state, please read the list of exported functions.

2. Dependencies

   2.1. Kamailio Modules
   2.2. External Libraries or Applications

2.1. Kamailio Modules

   The following modules must be loaded before this module:
     * none.

2.2. External Libraries or Applications

   The following libraries or applications must be installed before
   running Kamailio with this module loaded:
     * None

3. Parameters

   The module does not export any config parameter yet.

4. Functions

   4.1. sdp_remove_codecs_by_id(list)
   4.2. sdp_remove_codecs_by_name(list)
   4.3. sdp_remove_line_by_prefix(string)
   4.4. sdp_keep_codecs_by_id(list [, mtype])
   4.5. sdp_keep_codecs_by_name(list [, mtype])
   4.6. sdp_with_media(type)
   4.7. sdp_remove_media(type)
   4.8. sdp_with_transport(type)
   4.9. sdp_remove_transport(type)
   4.10. sdp_with_codecs_by_id(list)
   4.11. sdp_with_codecs_by_name(list)
   4.12. sdp_print(level)
   4.13. sdp_get(avpvar)
   4.14. sdp_content()
   4.15. sdp_get_line_startswith(avpvar, string)

4.1.  sdp_remove_codecs_by_id(list)

   Remove the codecs provided in the parameter 'list' from all media
   streams found in SDP payload. The parameter 'list' must be one item or
   a comma separated list of numeric codec IDs. The parameter can be a
   static string or a variable holding the list of numeric codec IDs.

   This function can be used from ANY_ROUTE.

   Example 1.1. sdp_remove_codecs_by_id usage
...
# remove PCMU
sdp_remove_codecs_by_id("0");
# remove PCMU, PCMA and GSM
sdp_remove_codecs_by_id("0,8,3");
...

4.2.  sdp_remove_codecs_by_name(list)

   Remove the codecs provided in the parameter 'list' from all media
   streams found in SDP payload. The parameter 'list' must be one item or
   a comma separated list of codec names. The parameter can be a static
   string or a variable holding the list of codec names.

   This function can be used from ANY_ROUTE.

   Example 1.2. sdp_remove_codecs_by_name usage
...
# remove PCMU
sdp_remove_codecs_by_name("PCMU");
# remove PCMU, PCMA and GSM
sdp_remove_codecs_by_name("PCMU,PCMA,GSM");
...

4.3.  sdp_remove_line_by_prefix(string)

   Remove all SDP attribute lines beginning with 'string' in all media
   streams.

   This function can be used from ANY_ROUTE.

   Example 1.3. sdp_remove_line_by_prefix usage
...
if ($si == "2001:DB8::8:800:200C:417A"
        and ( has_body("application/sdp") or has_body("multipart/mixed")))
{
    xlog("L_INFO", "Cleaning ugly SDP from $si\n");
    sdp_remove_codecs_by_name("X-NSE");
    sdp_remove_line_by_prefix("a=X-");
}

...

4.4.  sdp_keep_codecs_by_id(list [, mtype])

   Keep only the codecs provided in the parameter 'list' from all media
   streams found in SDP payload. The parameter 'list' must be one item or
   a comma separated list of numeric codec IDs. The parameter can be a
   static string or a variable holding the list of numeric codec IDs.

   Optional parameter mtype can be provided to apply the operations only
   to the streams matching m=mtype.

   This function can be used from ANY_ROUTE.

   Example 1.4. sdp_keep_codecs_by_id usage
...
# keep only PCMU
sdp_keep_codecs_by_id("0");
# keep PCMU, PCMA and GSM in audio stream
sdp_keep_codecs_by_id("0,8,3", "audio");
...

4.5.  sdp_keep_codecs_by_name(list [, mtype])

   Keep only the codecs provided in the parameter 'list' from all media
   streams found in SDP payload. The parameter 'list' must be one or a
   comma separated list of codec names. The parameter can be a static
   string or a variable holding the list of codec names.

   Optional parameter mtype can be provided to apply the operations only
   to the streams matching m=mtype.

   This function can be used from ANY_ROUTE.

   Example 1.5. sdp_keep_codecs_by_name usage
...
# keep only PCMU
sdp_keep_codecs_by_name("PCMU");
# keep PCMU, PCMA and GSM
sdp_keep_codecs_by_name("PCMU,PCMA,GSM");
...

4.6.  sdp_with_media(type)

   Return true of the SDP has 'media=type ...' line. Useful to check the
   content of the RTP sessions, such as 'audio' or 'video'. The parameter
   can be static string or variable holding the media type.

   This function can be used from ANY_ROUTE.

   Example 1.6. sdp_with_media usage
...
# check for video stream
if(sdp_with_media("video"))
{
    # the session has a video stream
}
...

4.7.  sdp_remove_media(type)

   Remove the streams that match on 'm=type ...' line. The parameter can
   be static string or variable holding the media type.

   This function can be used from ANY_ROUTE.

   Example 1.7. sdp_remove_media usage
...
# remove video stream
sdp_remove_media("video");
...

4.8.  sdp_with_transport(type)

   Return true of the SDP has 'media=media port type ...' line. Useful to
   check the transport of the RTP sessions, such as 'RTP/AVP', 'RTP/SAVP'
   or 'RTP/SAVPF'. The parameter can be static string or variable holding
   the transport type.

   This function can be used from ANY_ROUTE.

   Example 1.8. sdp_with_transport usage
...
# check for RTP/SAVP stream
if(sdp_with_transport("RTP/SAVP"))
{
    # the session has a SRTP/SAVP stream
}
...

4.9.  sdp_remove_transport(type)

   Remove the streams that match on 'm=media port type ...' line. The
   parameter can be static string or variable holding the transport type.

   This function can be used from ANY_ROUTE.

   Example 1.9. sdp_remove_transport usage
...
# remove stream with transport RTP/AVP
sdp_remove_transport("RTP/AVP");
...

4.10.  sdp_with_codecs_by_id(list)

   Returns true if any of the codecs provided in the parameter 'list' from
   all media streams is found in SDP payload. The parameter 'list' must be
   one or a comma separated list of numeric codec IDs. The parameter can
   be a static string or a variable holding the list of numeric codec IDs.

   This function can be used from ANY_ROUTE.

   Example 1.10. sdp_with_codecs_by_id usage
...
# test for PCMU
if(sdp_with_codecs_by_id("0")) { ... }
# test for PCMU, PCMA or GSM
if(sdp_with_codecs_by_id("0,8,3")) { ... }
...

4.11.  sdp_with_codecs_by_name(list)

   Returns true if any of the codecs provided in the parameter 'list' from
   all media streams is found in SDP payload. The parameter 'list' must be
   one item or a comma separated list of codec names. The parameter can be
   a static string or a variable holding the list of codec names.

   This function can be used from ANY_ROUTE.

   Example 1.11. sdp_with_codecs_by_name usage
...
# test for PCMU
if(sdp_with_codecs_by_name("PCMU")) { ... }
# test for PCMU, PCMA or GSM
if(sdp_with_codecs_by_name("PCMU,PCMA,GSM")) { ... }
...

4.12.  sdp_print(level)

   Print the SDP internal structure to log 'level'. The parameter can be
   static integer or variable holding the integer value of the log level.

   This function can be used from ANY_ROUTE.

   Example 1.12. sdp_print usage
...
# print the SDP
sdp_print("1");
...

4.13.  sdp_get(avpvar)

   Store the SDP part of message body in an AVP. Return 1 if SDP is found,
   -1 on error and -2 if there is no SDP part in the message body.

   This function can be used from ANY_ROUTE.

   Example 1.13. sdp_get usage
...
sdp_get("$avp(sdp)");
...

4.14.  sdp_content()

   Return true if the SIP message has SDP body or a SDP part in body.

   This function can be used from ANY_ROUTE.

   Example 1.14. sdp_content usage
...
if(sdp_content()) {
    ...
}
...

4.15.  sdp_get_line_startswith(avpvar, string)

   Store the search part of SDP body message with line beginning with
   'string' in an AVP. Return 1 if 'string' is found in SDP, -1 on error
   and -2 if there is no SDP part in the message body.

   This function can be used from ANY_ROUTE.

   Example 1.15. sdp_get_line_startswith usage
...
if(sdp_get_line_startswith("$avp(mline)", "m=")) {
        xlog("m-line: $avp(mline)\n");
}
...
