chan_sip: Prevent extra Session-Expires headers from being added

When chan_sip does a re-INVITE to refresh a session and authentication
is required, the INVITE with the Authorization header containes a
second Session-Expires header without the ";refersher=" parameter.
This is causing some proxies to return a 400.  Also, when Asterisk is
the uas and the refresher, it is including the Session-Expires and
Min-SE headers in OPTIONS messages which is not allowed per RFC4028.

This patch (based on the reporter's) Checks to see if a Session-Expires
header is already in the message before adding another one.  It also
checks that the method is INVITE or UPDATE.

ASTERISK-26030 #close

Change-Id: I58a7b07bab5a3177748d8a7034fb8ad8e11ce1d9

channels/chan_sip.c

@@ -14528,10 +14528,12 @@ static int transmit_invite(struct sip_pvt *p, int sipmethod, int sdp, int init,
 		add_header(&req, "Require", "replaces");
 	}
 
-	/* Add Session-Timers related headers */
-	if (st_get_mode(p, 0) == SESSION_TIMER_MODE_ORIGINATE
+	/* Add Session-Timers related headers if not already there */
+	if (ast_strlen_zero(sip_get_header(&req, "Session-Expires")) &&
+		(sipmethod == SIP_INVITE || sipmethod == SIP_UPDATE) &&
+		(st_get_mode(p, 0) == SESSION_TIMER_MODE_ORIGINATE
 		|| (st_get_mode(p, 0) == SESSION_TIMER_MODE_ACCEPT
-			&& st_get_se(p, FALSE) != DEFAULT_MIN_SE)) {
+			&& st_get_se(p, FALSE) != DEFAULT_MIN_SE))) {
 		char i2astr[10];
 
 		if (!p->stimer->st_interval) {