Don't do a DNS lookup on an outbound REGISTER host if there is an outbound proxy configured.

(closes issue ASTERISK-16550)
reported by: Olle Johansson
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Merged revisions 352424 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 352430 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@352431 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -13383,7 +13383,14 @@ static int transmit_register(struct sip_registry *r, int sipmethod, const char *
 		peer = sip_find_peer(r->hostname, NULL, TRUE, FINDPEERS, FALSE, 0);
 		snprintf(transport, sizeof(transport), "_%s._%s",get_srv_service(r->transport), get_srv_protocol(r->transport)); /* have to use static sip_get_transport function */
 		r->us.ss.ss_family = get_address_family_filter(&bindaddr); /* Filter address family */
-		ast_dnsmgr_lookup(peer ? peer->tohost : r->hostname, &r->us, &r->dnsmgr, sip_cfg.srvlookup ? transport : NULL);
+
+		/* No point in doing a DNS lookup of the register hostname if we're just going to
+		 * end up using an outbound proxy. obproxy_get is safe to call with either of r->call
+		 * or peer NULL. Since we're only concerned with its existence, we're not going to
+		 * bother getting a ref to the proxy*/
+		if (!obproxy_get(r->call, peer)) {
+			ast_dnsmgr_lookup(peer ? peer->tohost : r->hostname, &r->us, &r->dnsmgr, sip_cfg.srvlookup ? transport : NULL);
+		}
 		if (peer) {
 			peer = sip_unref_peer(peer, "removing peer ref for dnsmgr_lookup");
 		}