Re: [Sipp-users] asterisk/sipp rtp port bug?

[Dmitry Goncharov]

E.H.Eefting wrote:

After a lot of debugging with asterisk and sipp in pcap mode we found the following problem:

If asterisk is configured to allow rtp ports greater than 9999, it seems the last digit is trimmed away some how.

An example of a tcpdump followed by an immediate netstat shows this problem:
-192.168.13.198 is running sipp in uac_pcap mode.
-192.168.13.150 is the asterisk server.
-uac is sending packets to udp port 1830
-asterisk is listening on ports 18300 and 18301

If asterisk happens to choose a port below 10000 (a port that is 4 digits long), everything goes well. This looks like a SIP parser bug in sipp somewhere, since normally we dont have this problem with other sip clients.

The SIP protocol is text-based, so a parser bug makes sence, right?

Could somebody look into the sourcecode if this is right? If it IS a bug, it would certainly explain a lot for many people i think ;)

Edwin Eefting
http://www.syn-3.nl

-----------------------------------------(paste of terminal output)

[Syn-3] r...@darkstar.example.net /etc/asterisk# tcpdump -n -l src 192.168.13.198 and not port 22 or proto ICMP | head -20 ; netstat -nap| grep asterisk

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0:0, link-type EN10MB (Ethernet), capture size 68 bytes
.....
17:57:49.398169 IP 192.168.13.198.6016 > 192.168.13.150.1830: UDP, length 252
17:57:49.428113 IP 192.168.13.198.6016 > 192.168.13.150.1830: UDP, length 252
17:57:49.458880 IP 192.168.13.198.6016 > 192.168.13.150.1830: UDP, length 252

17:57:49.458939 IP 192.168.13.150 > 192.168.13.198: ICMP 192.168.13.150 udp port 1830 unreachable, length 288

17:57:49.488563 IP 192.168.13.198.6016 > 192.168.13.150.1830: UDP, length 252
17:57:49.517853 IP 192.168.13.198.6016 > 192.168.13.150.1830: UDP, length 252
.....
21 packets captured
48 packets received by filter
0 packets dropped by kernel

udp 0 0 0.0.0.0:5060 0.0.0.0:* 18189/asterisk udp 0 0 0.0.0.0:18300 0.0.0.0:* 18189/asterisk udp 0 0 0.0.0.0:18301 0.0.0.0:* 18189/asterisk udp 0 0 0.0.0.0:17278 0.0.0.0:* 18189/asterisk

Hi, Edwin

Yes, this is a bug in sipp. Here is your patch.

BR, Dmitry

diff -urb sipp.svn_orig/call.cpp sipp.svn_fixed/call.cpp
--- sipp.svn_orig/call.cpp      2008-12-19 13:14:51.000000000 +0300
+++ sipp.svn_fixed/call.cpp     2008-12-19 13:16:34.000000000 +0300
@@ -192,7 +192,7 @@
       /* m=audio not found */
       return 0;
     }
-    begin += strlen(pattern) - 1;
+    begin += strlen(pattern);
     end = strstr(begin, "\r\n");
     if (!end)
       ERROR("get_remote_port_media: no CRLF found");

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