Fixes issue with dropped calles due to re-Invite glare and re-Invites never executing after a 491

Acknowledgement for 491 responses were never being processed because it didn't match our pending invite's seqno.  Since the ACK was never processed, the 491 frame would continue to be retransmitted until eventually the call was dropped due to max retries.  Now during a pending invite, if we receive another invite, we send an 491 and hold on to that glare invite's seqno in the "glareinvite" variable for that sip_pvt struct.  When ACK's are received, we first check to see if it is in response to our pending invite, if not we check to see if it is in response to a glare invite.  In this case, it is in response to the glare invite and must be dealt with or the call is dropped.  I've changed the wait time for resending the re-Invite after receving a 491 response to comply with RFC 3261.  Before this patch the scheduled re-Invite would only change a flag indicating that the re-Invite should be sent out, now it actually sends it out as well. 

(closes issue #12013)
Reported by: alx

Review: http://reviewboard.digium.com/r/213/



git-svn-id: http://svn.digium.com/svn/asterisk/branches/1.4@185845 f38db490-d61c-443f-a65b-d21fe96a405b

1 files changed, 27 insertions, 9 deletions

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 4b8bb3730..26f835c7b 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -998,9 +998,12 @@ static struct sip_pvt {
 	char lastmsg[256];			/*!< Last Message sent/received */
 	int amaflags;				/*!< AMA Flags */
 	int pendinginvite;			/*!< Any pending INVITE or state NOTIFY (in subscribe pvt's) ? (seqno of this) */
+	int glareinvite;			/*!< A invite received while a pending invite is already present is stored here.  Its seqno is the
+						value. Since this glare invite's seqno is not the same as the pending invite's, it must be 
+						held in order to properly process acknowledgements for our 491 response. */
 	struct sip_request initreq;		/*!< Request that opened the latest transaction
 						     within this SIP dialog */
-	
+
 	int maxtime;				/*!< Max time for first response */
 	int initid;				/*!< Auto-congest ID if appropriate (scheduler) */
 	int waitid;				/*!< Wait ID for scheduler after 491 or other delays */
@@ -12313,7 +12316,7 @@ static void check_pendings(struct sip_pvt *p)
 				ast_log(LOG_DEBUG, "Sending pending reinvite on '%s'\n", p->callid);
 			/* Didn't get to reinvite yet, so do it now */
 			transmit_reinvite_with_sdp(p);
-			ast_clear_flag(&p->flags[0], SIP_NEEDREINVITE);	
+			ast_clear_flag(&p->flags[0], SIP_NEEDREINVITE);
 		}
 	}
 }
@@ -12322,12 +12325,15 @@ static void check_pendings(struct sip_pvt *p)
 	to avoid race conditions between asterisk servers.
 	Called from the scheduler.
 */
-static int sip_reinvite_retry(const void *data) 
+static int sip_reinvite_retry(const void *data)
 {
 	struct sip_pvt *p = (struct sip_pvt *) data;
 
-	ast_set_flag(&p->flags[0], SIP_NEEDREINVITE);	
+	ast_mutex_lock(&p->lock); /* called from schedule thread which requires a lock */
+	ast_set_flag(&p->flags[0], SIP_NEEDREINVITE);
 	p->waitid = -1;
+	check_pendings(p);
+	ast_mutex_unlock(&p->lock);
 	return 0;
 }
 
@@ -12340,7 +12346,7 @@ static void handle_response_invite(struct sip_pvt *p, int resp, char *rest, stru
 	int xmitres = 0;
 	int reinvite = (p->owner && p->owner->_state == AST_STATE_UP);
 	struct ast_channel *bridgepeer = NULL;
-	
+
 	if (option_debug > 3) {
 		if (reinvite)
 			ast_log(LOG_DEBUG, "SIP response %d to RE-invite on %s call %s\n", resp, outgoing ? "outgoing" : "incoming", p->callid);
@@ -12617,13 +12623,20 @@ static void handle_response_invite(struct sip_pvt *p, int resp, char *rest, stru
 		if (p->owner && !ast_test_flag(req, SIP_PKT_IGNORE)) {
 			if (p->owner->_state != AST_STATE_UP) {
 				ast_queue_control(p->owner, AST_CONTROL_CONGESTION);
-				ast_set_flag(&p->flags[0], SIP_NEEDDESTROY);	
+				ast_set_flag(&p->flags[0], SIP_NEEDDESTROY);
 			} else {
 				/* This is a re-invite that failed.
 				 * Reset the flag after a while 
 				 */
-				int wait = 3 + ast_random() % 5;
-				p->waitid = ast_sched_add(sched, wait, sip_reinvite_retry, p); 
+				int wait;
+				/* RFC 3261, if owner of call, wait between 2.1 to 4 seconds,
+				 * if not owner of call, wait 0 to 2 seconds */
+				if (ast_test_flag(&p->flags[1], SIP_PAGE2_OUTGOING_CALL)) {
+					wait = 2100 + ast_random() % 2000;
+				} else {
+					wait = ast_random() % 2000;
+				}
+				p->waitid = ast_sched_add(sched, wait, sip_reinvite_retry, p);
 				if (option_debug > 2)
 					ast_log(LOG_DEBUG, "Reinvite race. Waiting %d secs before retry\n", wait);
 			}
@@ -14322,6 +14335,7 @@ static int handle_request_invite(struct sip_pvt *p, struct sip_request *req, int
 	
 	if (!ast_test_flag(req, SIP_PKT_IGNORE) && p->pendinginvite) {
 		/* We already have a pending invite. Sorry. You are on hold. */
+		p->glareinvite = seqno;
 		transmit_response_reliable(p, "491 Request Pending", req);
 		if (option_debug)
 			ast_log(LOG_DEBUG, "Got INVITE on call where we already have pending INVITE, deferring that - %s\n", p->callid);
@@ -15972,8 +15986,12 @@ static int handle_request(struct sip_pvt *p, struct sip_request *req, struct soc
 			if (find_sdp(req)) {
 				if (process_sdp(p, req))
 					return -1;
-			} 
+			}
 			check_pendings(p);
+		} else if (p->glareinvite == seqno) {
+			/* handle ack for the 491 pending send for glareinvite */
+			p->glareinvite = 0;
+			__sip_ack(p, seqno, 1, 0);
 		}
 		/* Got an ACK that we did not match. Ignore silently */
 		if (!p->lastinvite && ast_strlen_zero(p->randdata))