Ensure the correct value is returned for CHANNEL(pjsip, secure)

Prior to this patch, we were using the PJSIP dialog's secure flag
to determine if a secure transport was being used. Unfortunately,
the dialog's secure flag was only set if a SIPS URI were in use,
as required by RFC 3261 sections 12.1.1 and 12.1.2. What we're interested
in is not dialog security, but transport security. This code change
switches to a model where we use the dialog's target URI to determine
what transport would be used to communicate, and then check if that
transport is secure.

AST-1450 #close
Reported by John Bigelow

Review: https://reviewboard.asterisk.org/r/4277
........

Merged revisions 429739 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@429740 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/pjsip/dialplan_functions.c

@@ -580,7 +580,11 @@ static int channel_read_pjsip(struct ast_channel *chan, const char *type, const
 	dlg = channel->session->inv_session->dlg;
 
 	if (!strcmp(type, "secure")) {
-		snprintf(buf, buflen, "%d", dlg->secure ? 1 : 0);
+		pjsip_host_info dest;
+		pj_pool_t *pool = pjsip_endpt_create_pool(ast_sip_get_pjsip_endpoint(), "secure-check", 128, 128);
+		pjsip_get_dest_info(dlg->target, NULL, pool, &dest);
+		snprintf(buf, buflen, "%d", dest.flag & PJSIP_TRANSPORT_SECURE ? 1 : 0);
+		pjsip_endpt_release_pool(ast_sip_get_pjsip_endpoint(), pool);
 	} else if (!strcmp(type, "target_uri")) {
 		pjsip_uri_print(PJSIP_URI_IN_REQ_URI, dlg->target, buf, buflen);
 		buf_copy = ast_strdupa(buf);