The call_token on the pvt can occasionally be NULL, causing a crash.

If it is NULL, we can skip this channel, since it can't the one we're looking for.

(closes issue #9299)
Reported by: vazir


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@114120 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_h323.c

@@ -1149,7 +1149,7 @@ static struct oh323_pvt *find_call_locked(int call_reference, const char *token)
 	while(pvt) {
 		if (!pvt->needdestroy && ((signed int)pvt->cd.call_reference == call_reference)) {
 			/* Found the call */
-			if ((token != NULL) && (!strcmp(pvt->cd.call_token, token))) {
+			if ((token != NULL) && (pvt->cd.call_token != NULL) && (!strcmp(pvt->cd.call_token, token))) {
 				ast_mutex_lock(&pvt->lock);
 				ast_mutex_unlock(&iflock);
 				return pvt;