Outbound Module
Peter Dunkley
Crocodile RCS Ltd
Copyright © 2012 Crocodile RCS Ltd
__________________________________________________________________
Table of Contents
1. Admin Guide
1. Overview
1.1. Edge Proxy Keep-Alives (STUN)
1.2. Flow Timer
2. Dependencies
2.1. Kamailio Modules
2.2. External Libraries or Applications
3. Parameters
3.1. force_outbound_flag (integer)
4. Functions
5. MI Commands
List of Examples
1.1. Edge Proxy Configuration
1.2. Registrar Configuration
1.3. Set force_outbound_flag parameter
Chapter 1. Admin Guide
Table of Contents
1. Overview
1.1. Edge Proxy Keep-Alives (STUN)
1.2. Flow Timer
2. Dependencies
2.1. Kamailio Modules
2.2. External Libraries or Applications
3. Parameters
3.1. force_outbound_flag (integer)
4. Functions
5. MI Commands
1. Overview
1.1. Edge Proxy Keep-Alives (STUN)
1.2. Flow Timer
This module provides C-API functions to enable Kamailio to be used as
an outbound Edge Proxy (see RFC 5626 section 5).
The path and rr will bind to this module if it is loaded before they
are.
1.1. Edge Proxy Keep-Alives (STUN)
Outbound Edge Proxies MUST support STUN NAT keep-alives on their SIP
UDP ports. Kamailio supports this though the “stun” module.
1.2. Flow Timer
The maximum interval at which a User Agent must send a keep-alive may
be specified by the Registrar using the Flow-Timer: header in 2xx
responses to REGISTERs.
When using TCP or TLS as the SIP transport care should be taken to set
the “tcp_connection_lifetime” on the Edge Proxy to a value slightly
larger than the interval the Registrar is using for flow timer. Setting
“tcp_connection_lifetime” to less than the interval could cause
connections to be lost, and setting it to a value much larger than the
interval will keep connections open far longer than is required (which
is wasteful).
Application-layer keep-alives are optional when the underlying
transport already has a keep-alive mechanism. The WebSocket transport
has a transport-layer keep-alive. When using the WebSocket transport
the “keepalive_timeout” should be set to a value a little greater than
the Registrar flow timer interval and a little less than the
“tcp_connection_lifetime”.
Example 1.1. Edge Proxy Configuration
#!KAMAILIO
#
# Edge proxy configuration
#
#!subst "/REGISTRAR_IP/192.168.122.3/"
#!subst "/REGISTRAR_PORT/5060/"
#!substdef "/FLOW_TIMER/20/"
####### Global Parameters #########
debug=2
log_stderror=no
log_facility=LOG_LOCAL0
fork=yes
children=4
alias="example.com"
mpath="/usr/lib64/kamailio/modules"
tcp_connection_lifetime=30 # FLOW_TIMER + 10
####### Modules Section ########
loadmodule "tm.so"
loadmodule "sl.so"
loadmodule "outbound.so"
loadmodule "rr.so"
loadmodule "path.so"
loadmodule "pv.so"
loadmodule "maxfwd.so"
loadmodule "xlog.so"
loadmodule "sanity.so"
loadmodule "ctl.so"
loadmodule "mi_rpc.so"
loadmodule "mi_fifo.so"
loadmodule "textops.so"
loadmodule "siputils.so"
loadmodule "stun.so"
# ----------------- setting module-specific parameters ---------------
# ----- mi_fifo params -----
modparam("mi_fifo", "fifo_name", "/tmp/kamailio_fifo")
# ----- tm params -----
modparam("tm", "failure_reply_mode", 3)
# ----- rr params -----
modparam("rr", "append_fromtag", 0)
####### Routing Logic ########
request_route {
route(REQINIT);
if (is_method("CANCEL")) {
if (t_check_trans()) {
route(RELAY);
}
exit;
}
route(WITHINDLG);
t_check_trans();
if (is_method("REGISTER")) {
remove_hf("Route");
add_path();
$du = "sip:REGISTRAR_IP:REGISTRAR_PORT";
} else {
if (is_method("INVITE|SUBSCRIBE"))
record_route();
if ($si == "REGISTRAR_IP" && $sp == "REGISTRAR_PORT") {
if (!loose_route()) {
switch($rc) {
case -2:
sl_send_reply("403", "Forbidden");
exit;
default:
sl_reply_error();
exit;
}
}
t_on_failure("FAIL_OUTBOUND");
} else {
if ($rU == $null) {
sl_send_reply("484", "Address Incomplete");
exit;
}
remove_hf("Route");
$du = "sip:REGISTRAR_IP:REGISTRAR_PORT";
}
}
route(RELAY);
}
route[RELAY] {
if (!t_relay()) {
sl_reply_error();
}
exit;
}
route[REQINIT] {
if (!mf_process_maxfwd_header("10")) {
sl_send_reply("483","Too Many Hops");
exit;
}
if(!sanity_check("1511", "7"))
{
xlog("Malformed SIP message from $si:$sp\n");
exit;
}
}
route[WITHINDLG] {
if (has_totag()) {
if (!loose_route()) {
switch($rc) {
case -2:
sl_send_reply("403", "Forbidden");
exit;
default:
if (is_method("ACK")) {
if ( t_check_trans() ) {
route(RELAY);
exit;
} else {
exit;
}
}
sl_send_reply("404","Not Found");
}
} else {
if (is_method("NOTIFY")) {
record_route();
}
route(RELAY);
}
exit;
}
}
onreply_route {
if (!t_check_trans()) {
drop;
}
if ($rm == "REGISTER" && $rs >= 200 && $rs <= 299) {
remove_hf("Flow-Timer");
if ($(hdr(Require)[*])=~"outbound")
insert_hf("Flow-Timer: FLOW_TIMER\r\n", "Call-ID");
}
}
failure_route[FAIL_OUTBOUND]{
if (t_branch_timeout() || !t_branch_replied()) {
send_reply("430", "Flow Failed");
}
}
Example 1.2. Registrar Configuration
...
loadmodule "tm.so"
...
loadmodule "registrar.so"
...
modparam("tm", "contacts_avp", "tm_contacts")
modparam("tm", "contact_flows_avp", "tm_contact_flows")
...
modparam("registrar", "use_path", 1)
modparam("registrar", "path_mode", 2)
modparam("registrar", "outbound_mode", 2)
...
route[LOCATION] {
...
if (!lookup("location")) {
$var(rc) = $rc;
route(TOVOICEMAIL);
t_newtran();
switch ($var(rc)) {
case -1:
case -3:
send_reply("404", "Not Found");
exit;
case -2:
send_reply("405", "Method Not Allowed");
exit;
}
}
if (!t_load_contacts()) {
send_reply("500", "Server Internal Error");
exit;
}
if (!t_next_contacts()) {
send_reply("500", "Server Internal Error");
exit;
}
t_on_failure("FAIL_OUTBOUND");
...
}
...
failure_route[FAIL_OUTBOUND] {
if (t_check_status("408|430")) {
if (!t_next_contact_flows() && !t_next_contacts()) {
send_reply("500", "Server Internal Error");
exit;
}
} else if (!t_next_contacts()) {
send_reply("500", "Server Internal Error");
exit;
}
t_on_failure("FAIL_OUTBOUND");
route(RELAY);
}
...
2. Dependencies
2.1. Kamailio Modules
2.2. External Libraries or Applications
2.1. Kamailio Modules
The following modules must be loaded before this module:
* None
2.2. External Libraries or Applications
The following libraries must be installed before running Kamailio with
this module loaded:
* OpenSSL.
3. Parameters
3.1. force_outbound_flag (integer)
3.1. force_outbound_flag (integer)
A flag which, if set for a request, will force path and rr to add flow
tokens to Path: and Record-Route: headers regardless of the request
contents.
Default value is -1.
Example 1.3. Set force_outbound_flag parameter
...
modparam("outbound", "force_outbound_flag", 1)
...
4. Functions
None
5. MI Commands
None