Function sdp_get gets extra blank line (when MIME is used) - sr-users

1 Nov 2024

The sdp_get() function from sdpops returns an extra blank line
sometimes, which looks like a bug to me. When I have an SDP that's in
MIME, there's an extra newline at the end of the extracted SDP.
Here's a sample config. I use 5.8.1 for testing.

####################
#!KAMAILIO
listen=udp:203.0.113.57:5060
debug=1
loadmodule "sdpops"
loadmodule "pv"
loadmodule "xlog"
request_route{exit;}
reply_route {
  sdp_get("$avp(sdp)");
  xlog("L_NOTICE", "[$ci] The SDP is [$avp(sdp)].\n");
}
####################

Here are two sample SIP-message bodies.
####################
v=0
o=PCD 1730 1730 IN IP4 198.18.114.148
s=PCD
c=IN IP4 198.18.114.148
t=0 0
m=audio 29426 RTP/AVP 0
a=rtpmap:0 PCMU/8000
####################

####################
--e61e7a6a-16a2-46c0-adbb-a41ba86d32a2
Content-Type: application/sdp
Content-Length: 130

v=0
o=PCD 1730 1730 IN IP4 198.18.114.148
s=PCD
c=IN IP4 198.18.114.148
t=0 0
m=audio 29426 RTP/AVP 0
a=rtpmap:0 PCMU/8000

--e61e7a6a-16a2-46c0-adbb-a41ba86d32a2--
####################

When the first body is received, the xlog correctly ends with this.
m=audio 29426 RTP/AVP 0
a=rtpmap:0 PCMU/8000
] with length 130

When the second body is received, the xlog incorrectly ends with this,
which has an extra newline in it.
m=audio 29426 RTP/AVP 0
a=rtpmap:0 PCMU/8000

] with length 132

According to RFC2046, "The CRLF preceding the boundary delimiter line
is conceptually attached to the boundary", but it looks like kamailio
has a bug that incorrectly processes this.

James