From 1318a3a2b7ded25de7ddbac1d4f5a4f3af846912 Mon Sep 17 00:00:00 2001
From: Francesco Castellano <francesco.castellano@messagenet.it>
Date: Fri, 28 Jun 2019 18:15:31 +0200
Subject: [PATCH] chan_sip: Handle invalid SDP answer to T.38 re-invite
The chan_sip module performs a T.38 re-invite using a single media
stream of udptl, and expects the SDP answer to be the same.
If an SDP answer is received instead that contains an additional
media stream with no joint codec a crash will occur as the code
assumes that at least one joint codec will exist in this
scenario.
This change removes this assumption.
ASTERISK-28465
Change-Id: I8b02845b53344c6babe867a3f0a5231045c7ac87
---
channels/chan_sip.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 7c8928db25..223ff3c85b 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -10911,7 +10911,13 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req, int t38action
ast_rtp_lookup_mime_multiple2(s3, NULL, newnoncodeccapability, 0, 0));
}
- if (portno != -1 || vportno != -1 || tportno != -1) {
+ /* When UDPTL is negotiated it is expected that there are no compatible codecs as audio or
+ * video is not being transported, thus we continue in this function further up if that is
+ * the case. If we receive an SDP answer containing both a UDPTL stream and another media
+ * stream however we need to check again to ensure that there is at least one joint codec
+ * instead of assuming there is one.
+ */
+ if ((portno != -1 || vportno != -1 || tportno != -1) && ast_format_cap_count(newjointcapability)) {
/* We are now ready to change the sip session and RTP structures with the offered codecs, since
they are acceptable */
unsigned int framing;
--
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