channels/chan_sip: Respect outboundproxy setting when sending qualify requests

The outboundproxy setting is currently ignored when sending OPTIONS requests
as a result of the qualify setting. This means that if an Asterisk server is
unable to send the packet directly to a peer, it is unable to qualify any
non-inbound registered peer (e.g. a peer SIP Trunk).

This patch grabs the outboundproxy information for a peer when a qualify
attempt is being constructed and, if it finds the information, uses it
when sending the OPTIONS request.

Review: https://reviewboard.asterisk.org/r/3948

ASTERISK-24063 #close
Reported by: Damian Ivereigh
patches:
  outboundproxy-dai.patch uploaded by Damian Ivereigh (License 6632)
........

Merged revisions 425818 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@425819 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -29561,6 +29561,9 @@ static int sip_poke_peer(struct sip_peer *peer, int force)
 	ast_copy_flags(&p->flags[1], &peer->flags[1], SIP_PAGE2_FLAGS_TO_COPY);
 	ast_copy_flags(&p->flags[2], &peer->flags[2], SIP_PAGE3_FLAGS_TO_COPY);
+	/* Get the outbound proxy information */
+	ref_proxy(p, obproxy_get(p, peer));
+
 	/* Send OPTIONs to peer's fullcontact */
 	if (!ast_strlen_zero(peer->fullcontact)) {
 		ast_string_field_set(p, fullcontact, peer->fullcontact);