detect sequence number rollover (bug #2887)

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/v1-0@4286 65c4cc65-6c06-0410-ace0-fbb531ad65f3

rtp.c

@@ -469,14 +469,14 @@ struct ast_frame *ast_rtp_read(struct ast_rtp *rtp)
 	  /* This is special in-band data that's not one of our codecs */
 	  if (rtpPT.code == AST_RTP_DTMF) {
 	    /* It's special -- rfc2833 process it */
-	    if (rtp->lasteventseqn <= seqno) {
+	    if (rtp->lasteventseqn <= seqno || rtp->resp == 0 || (rtp->lasteventseqn >= 65530 && seqno <= 6)) {
 	      f = process_rfc2833(rtp, rtp->rawdata + AST_FRIENDLY_OFFSET + hdrlen, res - hdrlen);
 	      rtp->lasteventseqn = seqno;
 	    } else f = NULL;
 	    if (f) return f; else return &null_frame;
 	  } else if (rtpPT.code == AST_RTP_CISCO_DTMF) {
 	    /* It's really special -- process it the Cisco way */
-	    if (rtp->lasteventseqn <= seqno) {
+	    if (rtp->lasteventseqn <= seqno || rtp->resp == 0 || (rtp->lasteventseqn >= 65530 && seqno <= 6)) {
 	      f = process_cisco_dtmf(rtp, rtp->rawdata + AST_FRIENDLY_OFFSET + hdrlen, res - hdrlen);
 	      rtp->lasteventseqn = seqno;
 	    } else f = NULL;