chan_sip: Don't use port derived from fromdomain if it isn't set

If a user does not provide a port in the fromdomain setting, chan_sip will set
the fromdomainport to STANDARD_SIP_PORT (5060). The fromdomainport value will
then get used unilaterally in certain places. This causes issues with TLS,
where the default port is expected to be 5061.

This patch modifies chan_sip such that fromdomainport is only used if it is
not the standard SIP port; otherwise, the port from the SIP pvt's recorded
self IP address is used.

Review: https://reviewboard.asterisk.org/r/3893/

ASTERISK-24178 #close
Reported by: Elazar Broad
patches:
  fromdomainport_fix.diff uploaded by Elazar Broad (License 5835)
........

Merged revisions 421717 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@421718 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -13795,7 +13795,7 @@ static void initreqprep(struct sip_request *req, struct sip_pvt *p, int sipmetho
 		ast_uri_encode(l, tmp_l, sizeof(tmp_l), ast_uri_sip_user);
 	}
-	ourport = (p->fromdomainport) ? p->fromdomainport : ast_sockaddr_port(&p->ourip);
+	ourport = (p->fromdomainport && (p->fromdomainport != STANDARD_SIP_PORT)) ? p->fromdomainport : ast_sockaddr_port(&p->ourip);
 	/* If a caller id name was specified, add a display name. */
 	if (cid_has_name || !cid_has_num) {
@@ -14737,7 +14737,7 @@ static int transmit_notify_with_mwi(struct sip_pvt *p, int newmsgs, int oldmsgs,
 {
 	struct sip_request req;
 	struct ast_str *out = ast_str_alloca(500);
-	int ourport = (p->fromdomainport) ? p->fromdomainport : ast_sockaddr_port(&p->ourip);
+	int ourport = (p->fromdomainport && (p->fromdomainport != STANDARD_SIP_PORT)) ? p->fromdomainport : ast_sockaddr_port(&p->ourip);
 	const char *domain;
 	const char *exten = S_OR(vmexten, default_vmexten);