Properly free memory and remove scheduler entries when a transmission failure occurs.

Previously, only the "data" field of the sip_pkt created during __sip_reliable_xmit 
was freed when XMIT_ERROR was returned by __sip_xmit. When retrans_pkt was called,
this inevitably resulted in the reading and writing of freed memory.

XMIT_ERROR is a condition meaning that we don't want to attempt resending the packet
at all. The proper action to take is to remove the scheduler entry we just created,
free the packet's data as well as the packet itself, and unlink it from the list of
packets on the sip_pvt structure.

(closes issue #14455)
Reported by: Nick_Lewis
Patches:
      14455.patch uploaded by mmichelson (license 60)
Tested by: Nick_Lewis



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@179219 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -3581,8 +3581,10 @@ static enum sip_result __sip_reliable_xmit(struct sip_pvt *p, int seqno, int res
 	if (xmitres == XMIT_ERROR) {	/* Serious network trouble, no need to try again */
 		append_history(pkt->owner, "XmitErr", "%s", pkt->is_fatal ? "(Critical)" : "(Non-critical)");
 		ast_log(LOG_ERROR, "Serious Network Trouble; __sip_xmit returns error for pkt data\n");
-		if (pkt->data)
-			ast_free(pkt->data);
+		AST_SCHED_DEL(sched, pkt->retransid);
+		p->packets = pkt->next;
+		ast_free(pkt->data);
+		ast_free(pkt);
 		return AST_FAILURE;
 	} else {
 		return AST_SUCCESS;