Accept T.38 re-INVITE responses with invalid SDP versions.

This commit changes the 'incoming SDP version' check logic a bit more; when
'ignoresdpversion' is *not* set for a peer, if we initiate a re-INVITE to
switch to T.38, we'll always accept the peer's SDP response, even if they
don't properly increment the SDP version number as they should. If this situation
occurs, a warning message will be generated suggesting that the peer's
configuration be changed to include the 'ignoresdpversion' configuration option
(although ideally they'd fix their SIP implementation to be RFC compliant).

AST-221

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@200689 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 100c52c1c2321f2305c26a1075228e7a870e9774..a35dd6409992b45c3f1c131b79ebf40844ceb3b8 100644 (file)
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -7824,16 +7824,39 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req, int t38action
                return -1;
        }
 
-       if (ast_test_flag(&p->flags[1], SIP_PAGE2_IGNORESDPVERSION)
-               || p->sessionversion_remote < 0
-               || p->sessionversion_remote != rua_version) {
-               
+       /* we need to check the SDP version number the other end sent us;
+        * our rules for deciding what to accept are a bit complex.
+        *
+        * 1) if 'ignoresdpversion' has been set for this dialog, then
+        *    we will just accept whatever they sent and assume it is
+        *    a modification of the session, even if it is not
+        * 2) otherwise, if this is the first SDP we've seen from them
+        *    we accept it
+        * 3) otherwise, if the new SDP version number is higher than the
+        *    old one, we accept it
+        * 4) otherwise, if this SDP is in response to us requesting a switch
+        *    to T.38, we accept the SDP, but also generate a warning message
+        *    that this peer should have the 'ignoresdpversion' option set,
+        *    because it is not following the SDP offer/answer RFC; if we did
+        *    not request a switch to T.38, then we stop parsing the SDP, as it
+        *    has not changed from the previous version
+        */
+
+       if (ast_test_flag(&p->flags[1], SIP_PAGE2_IGNORESDPVERSION) ||
+           (p->sessionversion_remote < 0) ||
+           (p->sessionversion_remote < rua_version)) {
                p->sessionversion_remote = rua_version;
                p->session_modify = TRUE;
-       } else if (p->sessionversion_remote == rua_version) {
-               p->session_modify = FALSE;
-               ast_debug(2, "SDP version number same as previous SDP. Not parsing this SDP.\n");
-               return 0;
+       } else {
+               if (p->t38.state == T38_LOCAL_REINVITE) {
+                       p->sessionversion_remote = rua_version;
+                       p->session_modify = TRUE;
+                       ast_log(LOG_WARNING, "Call %s responded to our T.38 reinvite without changing SDP version; 'ignoresdpversion' should be set for this peer.\n", p->callid);
+               } else {
+                       p->session_modify = FALSE;
+                       ast_debug(2, "Call %s responded to our reinvite without changing SDP version; ignoring SDP.\n", p->callid);
+                       return 0;
+               }
        } 
 
        /* Try to find first media stream */