Don't have the Via header stored as a stringfield as it can change often during the lifetime of a dialog.

This issue crept up with subscriptions on the AA50. When an outgoing NOTIFY is sent a new branch value
is created and the Via header is changed to reflect it. Since this was a stringfield a new spot in the
pool was used for the value while the old was left untouched/unused. If the current pool was full a new
pool was created. This would cause memory usage to increase steadily.

(issue #AA50-2332)


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@176029 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -947,12 +947,12 @@ static struct sip_pvt {
 		AST_STRING_FIELD(peermd5secret);
 		AST_STRING_FIELD(cid_num);	/*!< Caller*ID number */
 		AST_STRING_FIELD(cid_name);	/*!< Caller*ID name */
-		AST_STRING_FIELD(via);		/*!< Via: header */
 		AST_STRING_FIELD(fullcontact);	/*!< The Contact: that the UA registers with us */
 		AST_STRING_FIELD(our_contact);	/*!< Our contact header */
 		AST_STRING_FIELD(rpid);		/*!< Our RPID header */
 		AST_STRING_FIELD(rpid_from);	/*!< Our RPID From header */
 	);
+	char via[128];                          /*!< Via: header */
 	unsigned int ocseq;			/*!< Current outgoing seqno */
 	unsigned int icseq;			/*!< Current incoming seqno */
 	ast_group_t callgroup;			/*!< Call group */
@@ -1823,8 +1823,8 @@ static void build_via(struct sip_pvt *p)
 	const char *rport = ast_test_flag(&p->flags[0], SIP_NAT) & SIP_NAT_RFC3581 ? ";rport" : "";
 
 	/* z9hG4bK is a magic cookie.  See RFC 3261 section 8.1.1.7 */
-	ast_string_field_build(p, via, "SIP/2.0/UDP %s:%d;branch=z9hG4bK%08x%s",
-			       ast_inet_ntoa(p->ourip), ourport, (int) p->branch, rport);
+	snprintf(p->via, sizeof(p->via), "SIP/2.0/UDP %s:%d;branch=z9hG4bK%08x%s",
+		 ast_inet_ntoa(p->ourip), ourport, (int) p->branch, rport);
 }
 
 /*! \brief NAT fix - decide which IP address to use for ASterisk server?