####### Routing Logic ########


# Main SIP request routing logic
# - processing of any incoming SIP request starts with this route
# - note: this is the same as route { ... }
request_route {

	# per request initial checks
	route(REQINIT);

	# NAT detection
	route(NATDETECT);

	# CANCEL processing
	if (is_method("CANCEL")) {
		if (t_check_trans()) {
			route(RELAY);
		}
		exit;
	}

	# handle retransmissions
	if (!is_method("ACK")) {
		if(t_precheck_trans()) {
			t_check_trans();
			exit;
		}
		t_check_trans();
	}

	# handle requests within SIP dialogs
	route(WITHINDLG);

	### only initial requests (no To tag)

	# authentication
	route(AUTH);

	# record routing for dialog forming requests (in case they are routed)
	# - remove preloaded route headers
	remove_hf("Route");
	if (is_method("INVITE|SUBSCRIBE"))
		record_route();

	# account only INVITEs
	if (is_method("INVITE")) {
		setflag(FLT_ACC); # do accounting
	}

	# dispatch requests to foreign domains
	route(SIPOUT);

	### requests for my local domains

	# handle registrations
	route(REGISTRAR);

	if ($rU==$null) {
		# request with no Username in RURI
		sl_send_reply("484", "Address Incomplete");
		exit;
	}

	# user location service
	route(LOCATION);
}


route[RELAY] {
	# enable additional event routes for forwarded requests
	# - serial forking, RTP relaying handling, a.s.o.
	if (is_method("INVITE|BYE|SUBSCRIBE|UPDATE")) {
		if(!t_is_set("branch_route")) t_on_branch("MANAGE_BRANCH");
	}
	if (is_method("INVITE|SUBSCRIBE|UPDATE")) {
		if(!t_is_set("onreply_route")) t_on_reply("MANAGE_REPLY");
	}
	if (is_method("INVITE")) {
		if(!t_is_set("failure_route")) t_on_failure("MANAGE_FAILURE");
	}

	if (!t_relay()) {
		sl_reply_error();
	}
	exit;
}

# Per SIP request initial checks
route[REQINIT] {
	# no connect for sending replies
	set_reply_no_connect();
	# enforce symmetric signaling
	# - send back replies to the source address of request
	force_rport();

#!ifdef WITH_ANTIFLOOD
	# flood detection from same IP and traffic ban for a while
	# be sure you exclude checking trusted peers, such as pstn gateways
	# - local host excluded (e.g., loop to self)
	if(src_ip!=myself) {
		if($sht(ipban=>$si)!=$null) {
			# ip is already blocked
			xdbg("request from blocked IP - $rm from $fu (IP:$si:$sp)\n");
			exit;
		}
		if (!pike_check_req()) {
			xlog("L_ALERT", "ALERT: pike blocking $rm from $fu (IP:$si:$sp)\n");
			$sht(ipban=>$si) = 1;
			exit;
		}
	}
#!endif
	if($ua =~ "friendly|scanner|sipcli|sipvicious|VaxSIPUserAgent|pplsip") {
		# silent drop for scanners - uncomment next line if want to reply
		# sl_send_reply("200", "OK");
		exit;
	}

	if (!mf_process_maxfwd_header("10")) {
		sl_send_reply("483", "Too Many Hops");
		exit;
	}

	if(is_method("OPTIONS") && uri==myself && $rU==$null) {
		sl_send_reply("200", "Keepalive");
		exit;
	}

	if(!sanity_check("17895", "7")) {
		xlog("Malformed SIP request from $si:$sp\n");
		exit;
	}
}

# Handle requests within SIP dialogs
route[WITHINDLG] {
	if (!has_totag()) return;

	# sequential request within a dialog should
	# take the path determined by record-routing
	if (loose_route()) {
		route(DLGURI);
		if (is_method("BYE")) {
			setflag(FLT_ACC); # do accounting ...
			setflag(FLT_ACCFAILED); # ... even if the transaction fails
		}
		else if ( is_method("ACK") ) {
			# ACK is forwarded statelessly
			route(NATMANAGE);
		}
		else if ( is_method("NOTIFY") ) {
			# Add Record-Route for in-dialog NOTIFY as per RFC 6665.
			record_route();
		}
		route(RELAY);
		exit;
	}
	if ( is_method("ACK") ) {
		if ( t_check_trans() ) {
			# no loose-route, but stateful ACK;
			# must be an ACK after a 487
			# or e.g. 404 from upstream server
			route(RELAY);
			exit;
		} else {
			# ACK without matching transaction ... ignore and discard
			exit;
		}
	}
	sl_send_reply("404", "Not here");
	exit;
}

# Handle SIP registrations
route[REGISTRAR] {
	if (!is_method("REGISTER")) return;
	if(isflagset(FLT_NATS)) {
		setbflag(FLB_NATB);
#!ifdef WITH_NATSIPPING
		# do SIP NAT pinging
		setbflag(FLB_NATSIPPING);
#!endif
	}
	if (!save("location"))
		sl_reply_error();

	exit;
}

# User location service
route[LOCATION] {
	if (!lookup("location")) {
		$var(rc) = $rc;
		t_newtran();
		switch ($var(rc)) {
			case -1:
			case -3:
				send_reply("404", "Not Found");
				exit;
			case -2:
				send_reply("405", "Method Not Allowed");
				exit;
		}
	}

	# when routing via usrloc, log the missed calls also
	if (is_method("INVITE")) {
		setflag(FLT_ACCMISSED);
	}

	route(RELAY);
	exit;
}


# IP authorization and user uthentication
route[AUTH] {
#!ifdef WITH_AUTH

#!ifdef WITH_IPAUTH
	if((!is_method("REGISTER")) && allow_source_address()) {
		# source IP allowed
		return;
	}
#!endif

	if (is_method("REGISTER") || from_uri==myself) {
		# authenticate requests
		if (!auth_check("$fd", "subscriber", "1")) {
			auth_challenge("$fd", "0");
			exit;
		}
		# user authenticated - remove auth header
		if(!is_method("REGISTER|PUBLISH"))
			consume_credentials();
	}
	# if caller is not local subscriber, then check if it calls
	# a local destination, otherwise deny, not an open relay here
	if (from_uri!=myself && uri!=myself) {
		sl_send_reply("403", "Not relaying");
		exit;
	}

#!endif
	return;
}

# Caller NAT detection
route[NATDETECT] {
#!ifdef WITH_NAT
	force_rport();
	if (nat_uac_test("19")) {
		if (is_method("REGISTER")) {
			fix_nated_register();
		} else {
			if(is_first_hop())
				set_contact_alias();
		}
		setflag(FLT_NATS);
	}
#!endif
	return;
}

# RTPProxy control
route[NATMANAGE] {
#!ifdef WITH_NAT
	if (is_request()) {
		if(has_totag()) {
			if(check_route_param("nat=yes")) {
				setbflag(FLB_NATB);
			}
		}
	}
	if (!(isflagset(FLT_NATS) || isbflagset(FLB_NATB)))
		return;

	rtpproxy_manage("co");

	if (is_request()) {
		if (!has_totag()) {
			if(t_is_branch_route()) {
				add_rr_param(";nat=yes");
			}
		}
	}
	if (is_reply()) {
		if(isbflagset(FLB_NATB)) {
			set_contact_alias();
		}
	}
#!endif
	return;
}

# URI update for dialog requests
route[DLGURI] {
#!ifdef WITH_NAT
	if(!isdsturiset()) {
		handle_ruri_alias();
	}
#!endif
	return;
}

# Routing to foreign domains
route[SIPOUT] {
	if (uri==myself) return;

	append_hf("P-hint: outbound\r\n");
	route(RELAY);
	exit;
}

# Manage outgoing branches
branch_route[MANAGE_BRANCH] {
	xdbg("new branch [$T_branch_idx] to $ru\n");
	route(NATMANAGE);
}

# Manage incoming replies
onreply_route[MANAGE_REPLY] {
	xdbg("incoming reply\n");
	if(status=~"[12][0-9][0-9]")
		route(NATMANAGE);
}

# Manage failure routing cases
failure_route[MANAGE_FAILURE] {
	route(NATMANAGE);

	if (t_is_canceled()) {
		exit;
	}
}
