Finding an Attribute in an SDP Session Structure

The sdp_find_attribute() function searches the attribute list that is specified by the attr parameter for the attribute name that is specified by the name parameter.

Return Values: The sdp_find_attribute() function returns a pointer to the attribute (sdp_attr_t *) that is specified by the name parameter when the function completes successfully. In all other cases, the sdp_find_attribute() function returns a value of NULL.

Example 3–2 Using the sdp_find_attribute() Function

The incomplete SDP description in this example has an audio section.

m=audio 49170 RTP/AVP 0 8
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=sendonly
a=ptime:10000
a=maxptime:20000

/*
* Assuming that above description is parsed using sdp_parse and that
* the parsed structure is in "session" sdp_session_t structure.
*/

sdp_attr_t *ptime;
sdp_attr_t *max_ptime;
sdp_media_t *media = session->s_media;

if ((ptime = sdp_find_attribute(media->m_attr, "ptime")) == NULL)
/* ptime attribute not present */
else if((max_ptime = sdp_find_attribute(media->m_attr,
 "maxptime")) == NULL)
/* max_ptime attribute not present */