Description

When processing a multipart INVITE using the rtpengine module. The rtpengine_offer configuration function (called with default arguments) is stripping all bodies except the application/sdp MIME type body.

Troubleshooting

Reproduction

A client is sending an INVITE through a kamailio proxy paired with a rtpengine.

Client                                       Proxy                                       Server
  x        INVITE (SDP)         x                             x                             x
  x qqqqqqqqqqqqqqqqqqqqqqqqqq> x                             x                             x 
  x         100 Trying          x                             x                             x 
  x <qqqqqqqqqqqqqqqqqqqqqqqqqq x                             x                             x 
  x                             x                             x        INVITE (SDP)         x 
  x                             x                             x qqqqqqqqqqqqqqqqqqqqqqqqqq> x 
  x                             x                             x         100 Trying          x 
  x                             x                             x <qqqqqqqqqqqqqqqqqqqqqqqqqq x 
  x                             x                             x                             x 
  x                             x                             x                             x 
  x                             x                             x                             x 
  x                             x                             x                             x 
  x                             x                             x                             x 
  x                             x                             x                             x 
  x                             x                             x        200 OK (SDP)         x 
  x                             x                             x <qqqqqqqqqqqqqqqqqqqqqqqqqq x 
  x        200 OK (SDP)         x                             x                             x 
  x <qqqqqqqqqqqqqqqqqqqqqqqqqq x                             x                             x 

The INVITE contains a application/sdp body and one or several other bodies of different MIME types.

When the INVITE is going out of the proxy, all other bodies except the application/sdp MIME are filtered out.

While The INVITE "Content-Type" header is still fixed to :
Content-Type: multipart/mixed;boundary="[boundary value]"

RTP Engine receives only the SDP body on its socket and is rewritting well the RTP ports.

Debugging Data

(paste your debugging data here)

Log Messages

(paste your log messages here)

SIP Traffic

(paste your sip traffic here)

Possible Solutions

This issue has been introduced by the following commit : 36cb753.

rtpengine.c :

@@ -3328,6 +3328,7 @@ rtpengine_offer_answer(struct sip_msg *msg, const char *flags, int op, int more)
  	str body, newbody;
  	struct lump *anchor;
  	pv_value_t pv_val;
 +	str cur_body = {0, 0};
  
  	dict = rtpp_function_call_ok(&bencbuf, msg, op, flags, &body);
  	if (!dict)
 @@ -3357,7 +3358,12 @@ rtpengine_offer_answer(struct sip_msg *msg, const char *flags, int op, int more)
  			pkg_free(newbody.s);
  
  		} else {
 -			anchor = del_lump(msg, body.s - msg->buf, body.len, 0);
 +			/* get the body from the message as body ptr may have changed */
 +			cur_body.len = 0;
 +			cur_body.s = get_body(msg);
 +			cur_body.len = msg->buf + msg->len - cur_body.s;
 +
 +			anchor = del_lump(msg, cur_body.s - msg->buf, cur_body.len, 0);
  			if (!anchor) {
  				LM_ERR("del_lump failed\n");
  				goto error_free;

If this commit is removed, the previous behavior is restored.

This commit fixes a segfault: "rtpengine: fixed segfault when using read_sdp_pv", so it appears to me that this may be useful.

For, now I am not seeing why this is happening.

Additional Information

• Kamailio Version - output of kamailio -v

seen on:

version: kamailio 5.1.0 (x86_64/linux)
flags: STATS: Off, EXTRA_DEBUG, USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES
ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144, MAX_LISTEN 16, MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB
poll method support: poll, epoll_lt, epoll_et, sigio_rt, select.
id: unknown
compiled on 15:29:43 Feb  8 2018 with gcc 4.8.4

but I think that the same behavior will be seen on master.

• Operating System:

(paste your output here)

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