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Table of Contents

SIP SIMPLE Presence Made Simple with Kamailio 3.1.x

Author: Daniel-Constantin Mierla
2010-09-29
  * http://www.asipto.com
 
ChangeLog:
  * 2010-10-25: updated for Kamailio 3.1.0 release

New open source XCAP server offered by Kamailio and SER projects can be used with their integrated SIMPLE Presence server or as stand-alone XCAP server.

Kamailio (former OpenSER) v3.1.0 was released on October 6, 2010. v3.1.0 is the first release in so called 3.1.x series, meaning that any change to 'x' number will not affect database structure or configuration file language, but will mark a new release with bug fixes.

The purpose of this document is to show how to build a SIP SIMPLE Presence server with XCAP capabilities. Over past years, SIMPLE extensions became famous for their complexity, by mixing SIP and HTTP and not only. Here we talk about a solution that is simple as concept and easy to deploy, everything relaying on open source and free software.

Kamailio is used to provide SIP SIMPLE presence server and XCAP server functionalities, and SIP Communicator (latest build version) is used as SIP softphone.

About SIP SIMPLE Presence

Kamailio introduced support for SIP SIMPLE presence many years ago. However, the complexity of specifications and architecture still prevent it to take off properly in the market. One of the show stoppers was the interaction with an XCAP server. XCAP is an XML based protocol using HTTP to carry documents to be stored on server side and used in many case by SIP Presence server. Such documents can be:

  • buddy lists - your contacts
  • presence access and manipulation rules - who is allowed to see your presence status and how

While there are few XCAP server implementations, some are pricey being part of expensive application servers, others require tons of dependencies and practically impossible to install apart of several Linux distributions, enough to keep many SIP implementors far from them.

References

More about SIP SIMPLE presence and XCAP:

Embedded XCAP Server in Kamailio 3.1.x

Kamailio 3.0 was able to handle HTTP, used only to process XMLRPC requests. v3.1.0 introduces a new module, xhttp, which is able to handle any kind of HTTP request. In top of it can be used another new module, xcap_server, to process XCAP specific request sent over HTTP.

Worth to mention that xhttp and xcap_server modules are completely independent one from the other. Meaning that if you send XCAP documents over SIP (and that is easy and secure over TLS), Kamailio can handle them, it is just a matter of configuration file.

Hopefully, ability of handling XCAP requests over SIP will attract some softphone implementors, since they don't need anymore an HTTP stack.

With the new xcap_server module, Kamailio 3.1.x completes the set of components required for a full implementation of SIP SIMPLE Presence server. The key benefits are:

  • all-in-one solution - no need for external applications or exotic dependencies
  • easy installation - it is installed with kamailio, runs wherever kamailio runs, it needs only libxml2 which is a requirement for the other old presence modules
  • you can do XCAP operations via HTTP, HTTPS, and SIP (over TLS, TCP, UDP or SCTP)
  • huge scalability - practically, the embedded xhttp and xcap_modules reuse the transport layer for core of Kamailio, meaning you get the same processing rate as for SIP traffic. Also, all the code is compiled, no interpreted language.
  • security
    • all security modules provided by Kamailio can be used, including digest authentication (you can authenticate with SIP username and password), IP filtering, etc.
    • one port for both protocols - Kamailio is able to handle at the same time SIP and HTTP requests sent to port 5060 (or port 5061 in case of TLS connection (SIPS or HTTPS)), therefore less ports that should be left open in your firewall
  • lightweight and compact solution - in case you want to run on embedded or limited resources system, you don't get a better option - everything is inside SIP server instance, compiled to machine code.
  • simple to use - it is what this document tries to prove

You can browse the documentation for xhttp and xcap_server modules at:

Deployment Description

The Operating System used for this tutorial is Ubuntu 10.04, but we will use the generic installation from sources that applies to all Unix/Linux based distributions.

Requirements are the same as for old presence modules:

  • core requirements: gcc, flex, bison, make, …, see stock installation guidelines
  • mysql server, client tool and library
  • libxml2 library and development headers (libxml2-dev)
  • optional: libssl library and development headers if you want to do XCAP over HTTPS/SIPS

As SIP softphone I used SIP Communicator, latest build, I haven't found a better free or open source alternative with nice GUI. SIP Communicator is written in Java, therefore very portable, apart of its large set of features that includes SIP SIMPLE presence and XCAP support.

The main focus in next sections is to show how to configure Kamailio to handle SIP SIMPLE presence and XCAP for storing buddy list and presence rules. There are other extensions of SIP SIMPLE that Kamailio supports, less common in practice, that will be skipped this time.

Kamailio Installation

For the sake of cleanness, this tutorial install Kamailio from sources, in a custom directory: /usr/local/kamailio-3.1-xcap. This allows to avoid conflicts with other existing installations and very easy uninstall by just removing that folder. If you want default installation, just remove PREFIX=/usr/local/kamailio-3.1-xcap from 'make cfg' command below.

Getting sources from GIT and install: 

  cd /usr/local/src/
  git clone --depth 1 git://git.sip-router.org/sip-router kamailio-3.1.0
  cd kamailio-3.1.0
  git checkout -b 3.1 origin/3.1
  make PREFIX=/usr/local/kamailio-3.1-xcap FLAVOUR=kamailio \
          include_modules="db_mysql presence presence_xml xhttp xcap_server" cfg
  make all
  make install

If you prefer to install from APT repository for Debian or Ubuntu distributions, then check:

In this case, you have to adapt the commands and content of config for the location of the files installed from deb packages.

Add users

Edit /usr/local/kamailio-3.1-xcap/etc/kamailio/kamctlrc to set SIP_DOMAIN=yourdomain (or to your server ip) and DBENGINE=MYSQL. 

SIP_DOMAIN=192.168.178.23
DBENGINE=MYSQL

Then create the database: 

/usr/local/kamailio-3.1-xcap/sbin/kamdbctl create

Note: be sure you create presence tables.

Add your users: 

/usr/local/kamailio-3.1-xcap/sbin/kamctl add alice alice123
/usr/local/kamailio-3.1-xcap/sbin/kamctl add bob bob123

To add users, you can use SIREMIS web management interface, more details about it at:

Start Kamailio

For the purpose of particular tutorial, you can start kamailio with: 

/usr/local/kamailio-3.1-xcap/sbin/kamailio

You can stop it with: 

killall kamailio

For alternatives, like init.d scripts for start/stop, see documentation on the website of Kamailio project.

Configuration File

Replace /usr/local/kamailio-3.1-xcap/etc/kamailio/kamailio.cfg with: 

#!KAMAILIO
#
# Kamailio (OpenSER) SIP Server v3.1 - default configuration script
#     - web: http://www.kamailio.org
#     - git: http://sip-router.org
#
# Direct your questions about this file to: <sr-users@lists.sip-router.org>
#
# Refer to the Core CookBook at http://www.kamailio.org/dokuwiki/doku.php
# for an explanation of possible statements, functions and parameters.
#
# Several features can be enabled using '#!define WITH_FEATURE' directives:
#
# *** To run in debug mode: 
#     - define WITH_DEBUG
#
# *** To enable mysql: 
#     - define WITH_MYSQL
#
# *** To enable authentication execute:
#     - enable mysql
#     - define WITH_AUTH
#     - add users using 'kamctl'
#
# *** To enable IP authentication execute:
#     - enable mysql
#     - enable authentication
#     - define WITH_IPAUTH
#     - add IP addresses with group id '1' to 'address' table
#
# *** To enable persistent user location execute:
#     - enable mysql
#     - define WITH_USRLOCDB
#
# *** To enable presence server execute:
#     - enable mysql
#     - define WITH_PRESENCE
#
# *** To enable nat traversal execute:
#     - define WITH_NAT
#     - install RTPProxy: http://www.rtpproxy.org
#     - start RTPProxy:
#        rtpproxy -l _your_public_ip_ -s udp:localhost:7722
#
# *** To enable PSTN gateway routing execute:
#     - define WITH_PSTN
#     - set the value of pstn.gw_ip
#     - check route[PSTN] for regexp routing condition
#
# *** To enable database aliases lookup execute:
#     - enable mysql
#     - define WITH_ALIASDB
#
# *** To enable multi-domain support execute:
#     - enable mysql
#     - define WITH_MULTIDOMAIN
#
# *** To enable TLS support execute:
#     - adjust CFGDIR/tls.cfg as needed
#     - define WITH_TLS
#
# *** To enable anti-flood detection execute:
#     - adjust pike and htable=>ipban settings as needed (default is
#       block if more than 16 requests in 2 seconds and ban for 300 seconds)
#     - define WITH_ANTIFLOOD
#
# *** To enhance accounting execute:
#     - enable mysql
#     - define WITH_ACCDB
#     - add following columns to database
#!ifdef ACCDB_COMMENT
  ALTER TABLE acc ADD COLUMN src_user VARCHAR(64) NOT NULL DEFAULT '';
  ALTER TABLE acc ADD COLUMN src_domain VARCHAR(128) NOT NULL DEFAULT '';
  ALTER TABLE acc ADD COLUMN dst_ouser VARCHAR(64) NOT NULL DEFAULT '';
  ALTER TABLE acc ADD COLUMN dst_user VARCHAR(64) NOT NULL DEFAULT '';
  ALTER TABLE acc ADD COLUMN dst_domain VARCHAR(128) NOT NULL DEFAULT '';
  ALTER TABLE missed_calls ADD COLUMN src_user VARCHAR(64) NOT NULL DEFAULT '';
  ALTER TABLE missed_calls ADD COLUMN src_domain VARCHAR(128) NOT NULL DEFAULT '';
  ALTER TABLE missed_calls ADD COLUMN dst_ouser VARCHAR(64) NOT NULL DEFAULT '';
  ALTER TABLE missed_calls ADD COLUMN dst_user VARCHAR(64) NOT NULL DEFAULT '';
  ALTER TABLE missed_calls ADD COLUMN dst_domain VARCHAR(128) NOT NULL DEFAULT '';
#!endif
 
####### Defined Values #########
#!define WITH_MYSQL
#!define WITH_AUTH
#!define WITH_PRESENCE
#!define WITH_XCAPSRV
 
# *** Value defines - IDs used later in config
#!ifdef WITH_MYSQL
# - database URL - used to connect to database server by modules such
#       as: auth_db, acc, usrloc, a.s.o.
#!define DBURL "mysql://openser:openserrw@localhost/openser"
#!endif
#!ifdef WITH_MULTIDOMAIN
# - the value for 'use_domain' parameters
#!define MULTIDOMAIN 1
#!else
#!define MULTIDOMAIN 0
#!endif
 
# - flags
#   FLT_ - per transaction (message) flags
#	FLB_ - per branch flags
#!define FLT_ACC 1
#!define FLT_ACCMISSED 2
#!define FLT_ACCFAILED 3
#!define FLT_NATS 5
 
#!define FLB_NATB 6
#!define FLB_NATSIPPING 7
 
####### Global Parameters #########
 
#!ifdef WITH_DEBUG
debug=4
log_stderror=yes
#!else
debug=2
log_stderror=no
#!endif
 
memdbg=5
memlog=5
 
log_facility=LOG_LOCAL0
 
fork=yes
children=4
 
/* uncomment the next line to disable TCP (default on) */
#disable_tcp=yes
 
/* uncomment the next line to disable the auto discovery of local aliases
   based on reverse DNS on IPs (default on) */
#auto_aliases=no
 
/* add local domain aliases */
#alias="sip.mydomain.com"
 
/* uncomment and configure the following line if you want Kamailio to 
   bind on a specific interface/port/proto (default bind on all available) */
#listen=udp:10.0.0.10:5060
 
/* port to listen to
 * - can be specified more than once if needed to listen on many ports */
port=5060
 
#!ifdef WITH_TLS
enable_tls=yes
#!endif
 
tcp_connection_lifetime=3604
 
#!ifdef WITH_XCAPSRV
tcp_accept_no_cl=yes
#!endif
 
####### Custom Parameters #########
 
# These parameters can be modified runtime via RPC interface
# - see the documentation of 'cfg_rpc' module.
#
# Format: group.id = value 'desc' description
# Access: $sel(cfg_get.group.id) or @cfg_get.group.id
#
 
#!ifdef WITH_PSTN
# PSTN GW Routing
#
# - pstn.gw_ip: valid IP or hostname as string value, example:
# pstn.gw_ip = "10.0.0.101" desc "My PSTN GW Address"
#
# - by default is empty to avoid misrouting
pstn.gw_ip = "" desc "PSTN GW Address"
#!endif
 
 
####### Modules Section ########
 
# set paths to location of modules
#!ifdef LOCAL_TEST_RUN
mpath="modules_k:modules"
#!else
mpath="/usr/local/kamailio-3.1-xcap/lib/kamailio/modules_k/:/usr/local/kamailio-3.1-xcap/lib/kamailio/modules/"
#!endif
 
#!ifdef WITH_MYSQL
loadmodule "db_mysql.so"
#!endif
 
loadmodule "mi_fifo.so"
loadmodule "kex.so"
loadmodule "tm.so"
loadmodule "tmx.so"
loadmodule "sl.so"
loadmodule "rr.so"
loadmodule "pv.so"
loadmodule "maxfwd.so"
loadmodule "usrloc.so"
loadmodule "registrar.so"
loadmodule "textops.so"
loadmodule "siputils.so"
loadmodule "xlog.so"
loadmodule "sanity.so"
loadmodule "ctl.so"
loadmodule "mi_rpc.so"
loadmodule "acc.so"
 
#!ifdef WITH_AUTH
loadmodule "auth.so"
loadmodule "auth_db.so"
#!ifdef WITH_IPAUTH
loadmodule "permissions.so"
#!endif
#!endif
 
#!ifdef WITH_ALIASDB
loadmodule "alias_db.so"
#!endif
 
#!ifdef WITH_MULTIDOMAIN
loadmodule "domain.so"
#!endif
 
#!ifdef WITH_PRESENCE
loadmodule "presence.so"
loadmodule "presence_xml.so"
#!endif
 
#!ifdef WITH_NAT
loadmodule "nathelper.so"
loadmodule "rtpproxy.so"
#!endif
 
#!ifdef WITH_TLS
loadmodule "tls.so"
#!endif
 
#!ifdef WITH_ANTIFLOOD
loadmodule "htable.so"
loadmodule "pike.so"
#!endif
 
#!ifdef WITH_XCAPSRV
loadmodule "xhttp.so"
loadmodule "xcap_server.so"
#!endif
 
# ----------------- setting module-specific parameters ---------------
 
 
# ----- mi_fifo params -----
modparam("mi_fifo", "fifo_name", "/tmp/kamailio_fifo")
 
 
# ----- tm params -----
# auto-discard branches from previous serial forking leg
modparam("tm", "failure_reply_mode", 3)
# default retransmission timeout: 30sec
modparam("tm", "fr_timer", 30000)
# default invite retransmission timeout after 1xx: 120sec
modparam("tm", "fr_inv_timer", 120000)
 
 
# ----- rr params -----
# add value to ;lr param to cope with most of the UAs
modparam("rr", "enable_full_lr", 1)
# do not append from tag to the RR (no need for this script)
modparam("rr", "append_fromtag", 0)
 
 
# ----- registrar params -----
modparam("registrar", "method_filtering", 1)
/* uncomment the next line to disable parallel forking via location */
# modparam("registrar", "append_branches", 0)
/* uncomment the next line not to allow more than 10 contacts per AOR */
#modparam("registrar", "max_contacts", 10)
 
 
# ----- acc params -----
/* what special events should be accounted ? */
modparam("acc", "early_media", 0)
modparam("acc", "report_ack", 0)
modparam("acc", "report_cancels", 0)
/* by default ww do not adjust the direct of the sequential requests.
   if you enable this parameter, be sure the enable "append_fromtag"
   in "rr" module */
modparam("acc", "detect_direction", 0)
/* account triggers (flags) */
modparam("acc", "log_flag", FLT_ACC)
modparam("acc", "log_missed_flag", FLT_ACCMISSED)
modparam("acc", "log_extra", 
	"src_user=$fU;src_domain=$fd;dst_ouser=$tU;dst_user=$rU;dst_domain=$rd")
modparam("acc", "failed_transaction_flag", FLT_ACCFAILED)
/* enhanced DB accounting */
#!ifdef WITH_ACCDB
modparam("acc", "db_flag", FLT_ACC)
modparam("acc", "db_missed_flag", FLT_ACCMISSED)
modparam("acc", "db_url", DBURL)
modparam("acc", "db_extra",
	"src_user=$fU;src_domain=$fd;dst_ouser=$tU;dst_user=$rU;dst_domain=$rd")
#!endif
 
 
# ----- usrloc params -----
/* enable DB persistency for location entries */
#!ifdef WITH_USRLOCDB
modparam("usrloc", "db_url", DBURL)
modparam("usrloc", "db_mode", 2)
modparam("usrloc", "use_domain", MULTIDOMAIN)
#!endif
 
 
# ----- auth_db params -----
#!ifdef WITH_AUTH
modparam("auth_db", "db_url", DBURL)
modparam("auth_db", "calculate_ha1", yes)
modparam("auth_db", "password_column", "password")
modparam("auth_db", "load_credentials", "")
modparam("auth_db", "use_domain", MULTIDOMAIN)
 
# ----- permissions params -----
#!ifdef WITH_IPAUTH
modparam("permissions", "db_url", DBURL)
modparam("permissions", "db_mode", 1)
#!endif
 
#!endif
 
 
# ----- alias_db params -----
#!ifdef WITH_ALIASDB
modparam("alias_db", "db_url", DBURL)
modparam("alias_db", "use_domain", MULTIDOMAIN)
#!endif
 
 
# ----- domain params -----
#!ifdef WITH_MULTIDOMAIN
modparam("domain", "db_url", DBURL)
# use caching
modparam("domain", "db_mode", 1)
# register callback to match myself condition with domains list
modparam("domain", "register_myself", 1)
#!endif
 
 
#!ifdef WITH_PRESENCE
# ----- presence params -----
modparam("presence", "db_url", DBURL)
modparam("presence", "fallback2db", 1)
modparam("presence", "db_update_period", 20)
 
# ----- presence_xml params -----
modparam("presence_xml", "db_url", DBURL)
modparam("presence_xml", "force_active", 0)
modparam("presence_xml", "integrated_xcap_server", 1)
#!endif
 
 
#!ifdef WITH_NAT
# ----- rtpproxy params -----
modparam("rtpproxy", "rtpproxy_sock", "udp:127.0.0.1:7722")
 
# ----- nathelper params -----
modparam("nathelper", "natping_interval", 30)
modparam("nathelper", "ping_nated_only", 1)
modparam("nathelper", "sipping_bflag", FLB_NATSIPPING)
modparam("nathelper", "sipping_from", "sip:pinger@kamailio.org")
 
# params needed for NAT traversal in other modules
modparam("nathelper|registrar", "received_avp", "$avp(RECEIVED)")
modparam("usrloc", "nat_bflag", FLB_NATB)
#!endif
 
 
#!ifdef WITH_TLS
# ----- tls params -----
modparam("tls", "config", "/tmp/kamailio-xcap/etc/kamailio/tls.cfg")
#!endif
 
#!ifdef WITH_ANTIFLOOD
# ----- pike params -----
modparam("pike", "sampling_time_unit", 2)
modparam("pike", "reqs_density_per_unit", 16)
modparam("pike", "remove_latency", 4)
 
# ----- htable params -----
# ip ban htable with autoexpire after 5 minutes
modparam("htable", "htable", "ipban=>size=8;autoexpire=300;")
#!endif
 
#!ifdef WITH_XCAPSRV
# ----- xcap_server params -----
modparam("xcap_server", "db_url", DBURL)
#!endif
 
####### Routing Logic ########
 
 
# Main SIP request routing logic
# - processing of any incoming SIP request starts with this route
route {
 
	# per request initial checks
	route(REQINIT);
 
	# NAT detection
	route(NAT);
 
	# handle requests within SIP dialogs
	route(WITHINDLG);
 
	### only initial requests (no To tag)
 
	# CANCEL processing
	if (is_method("CANCEL"))
	{
		if (t_check_trans())
			t_relay();
		exit;
	}
 
	t_check_trans();
 
	# 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 presence related requests
	route(PRESENCE);
 
	# handle registrations
	route(REGISTRAR);
 
	if ($rU==$null)
	{
		# request with no Username in RURI
		sl_send_reply("484","Address Incomplete");
		exit;
	}
 
	# dispatch destinations to PSTN
	route(PSTN);
 
	# user location service
	route(LOCATION);
 
	route(RELAY);
}
 
 
route[RELAY] {
#!ifdef WITH_NAT
	if (check_route_param("nat=yes")) {
		setbflag(FLB_NATB);
	}
	if (isflagset(FLT_NATS) || isbflagset(FLB_NATB)) {
		route(RTPPROXY);
	}
#!endif
 
	/* example how to enable some additional event routes */
	if (is_method("INVITE")) {
		#t_on_branch("BRANCH_ONE");
		t_on_reply("REPLY_ONE");
		t_on_failure("FAIL_ONE");
	}
 
	if (!t_relay()) {
		sl_reply_error();
	}
	exit;
}
 
# Per SIP request initial checks
route[REQINIT] {
#!ifdef WITH_ANTIFLOOD
	# flood dection 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 (!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;
	}
}
 
# Handle requests within SIP dialogs
route[WITHINDLG] {
	if (has_totag()) {
		# sequential request withing a dialog should
		# take the path determined by record-routing
		if (loose_route()) {
			if (is_method("BYE")) {
				setflag(FLT_ACC); # do accounting ...
				setflag(FLT_ACCFAILED); # ... even if the transaction fails
			}
			route(RELAY);
		} else {
			if (is_method("SUBSCRIBE") && uri == myself) {
				# in-dialog subscribe requests
				route(PRESENCE);
				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
					t_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"))
	{
		if(isflagset(FLT_NATS))
		{
			setbflag(FLB_NATB);
			# uncomment next line to do SIP NAT pinging 
			## setbflag(FLB_SIPPING);
		}
		if (!save("location"))
			sl_reply_error();
 
		exit;
	}
}
 
# USER location service
route[LOCATION] {
 
#!ifdef WITH_ALIASDB
	# search in DB-based aliases
	alias_db_lookup("dbaliases");
#!endif
 
	if (!lookup("location")) {
		switch ($rc) {
			case -1:
			case -3:
				t_newtran();
				t_reply("404", "Not Found");
				exit;
			case -2:
				sl_send_reply("405", "Method Not Allowed");
				exit;
		}
	}
 
	# when routing via usrloc, log the missed calls also
	if (is_method("INVITE"))
	{
		setflag(FLT_ACCMISSED);
	}
}
 
# Presence server route
route[PRESENCE] {
	if(!is_method("PUBLISH|SUBSCRIBE"))
		return;
 
#!ifdef WITH_PRESENCE
	if (!t_newtran())
	{
		sl_reply_error();
		exit;
	};
 
	if(is_method("PUBLISH"))
	{
		handle_publish();
		t_release();
	}
	else
	if( is_method("SUBSCRIBE"))
	{
		handle_subscribe();
		t_release();
	}
	exit;
#!endif
 
	# if presence enabled, this part will not be executed
	if (is_method("PUBLISH") || $rU==$null)
	{
		sl_send_reply("404", "Not here");
		exit;
	}
	return;
}
 
# Authentication route
route[AUTH] {
#!ifdef WITH_AUTH
	if (is_method("REGISTER"))
	{
		# authenticate the REGISTER requests (uncomment to enable auth)
		if (!www_authorize("$td", "subscriber"))
		{
			www_challenge("$td", "0");
			exit;
		}
 
		if ($au!=$tU)
		{
			sl_send_reply("403","Forbidden auth ID");
			exit;
		}
	} else {
 
#!ifdef WITH_IPAUTH
		if(allow_source_address())
		{
			# source IP allowed
			return;
		}
#!endif
 
		# authenticate if from local subscriber
		if (from_uri==myself)
		{
			if (!proxy_authorize("$fd", "subscriber")) {
				proxy_challenge("$fd", "0");
				exit;
			}
			if (is_method("PUBLISH"))
			{
				if ($au!=$tU) {
					sl_send_reply("403","Forbidden auth ID");
					exit;
				}
			} else {
				if ($au!=$fU) {
					sl_send_reply("403","Forbidden auth ID");
					exit;
				}
			}
 
			consume_credentials();
			# caller authenticated
		} else {
			# caller is not local subscriber, then check if it calls
			# a local destination, otherwise deny, not an open relay here
			if (!uri==myself)
			{
				sl_send_reply("403","Not relaying");
				exit;
			}
		}
	}
#!endif
	return;
}
 
# Caller NAT detection route
route[NAT] {
#!ifdef WITH_NAT
	force_rport();
	if (nat_uac_test("19")) {
		if (method=="REGISTER") {
			fix_nated_register();
		} else {
			fix_nated_contact();
		}
		setflag(FLT_NATS);
	}
#!endif
	return;
}
 
# RTPProxy control
route[RTPPROXY] {
#!ifdef WITH_NAT
	if (is_method("BYE")) {
		unforce_rtp_proxy();
	} else if (is_method("INVITE")){
		force_rtp_proxy();
	}
	if (!has_totag()) add_rr_param(";nat=yes");
#!endif
	return;
}
 
# Routing to foreign domains
route[SIPOUT] {
	if (!uri==myself)
	{
		append_hf("P-hint: outbound\r\n");
		route(RELAY);
	}
}
 
# PSTN GW routing
route[PSTN] {
#!ifdef WITH_PSTN
	# check if PSTN GW IP is defined
	if (strempty($sel(cfg_get.pstn.gw_ip))) {
		xlog("SCRIPT: PSTN rotuing enabled but pstn.gw_ip not defined\n");
		return;
	}
 
	# route to PSTN dialed numbers starting with '+' or '00'
	#     (international format)
	# - update the condition to match your dialing rules for PSTN routing
	if(!($rU=~"^(\+|00)[1-9][0-9]{3,20}$"))
		return;
 
	# only local users allowed to call
	if(from_uri!=myself) {
		sl_send_reply("403", "Not Allowed");
		exit;
	}
 
	$ru = "sip:" + $rU + "@" + $sel(cfg_get.pstn.gw_ip);
 
	route(RELAY);
	exit;
#!endif
 
	return;
}
 
# Sample branch router
branch_route[BRANCH_ONE] {
	xdbg("new branch at $ru\n");
}
 
# Sample onreply route
onreply_route[REPLY_ONE] {
	xdbg("incoming reply\n");
#!ifdef WITH_NAT
	if ((isflagset(FLT_NATS) || isbflagset(FLB_NATB))
			&& status=~"(183)|(2[0-9][0-9])") {
		force_rtp_proxy();
	}
	if (isbflagset("6")) {
		fix_nated_contact();
	}
#!endif
}
 
# Sample failure route
failure_route[FAIL_ONE] {
#!ifdef WITH_NAT
	if (is_method("INVITE")
			&& (isbflagset(FLB_NATB) || isflagset(FLT_NATS))) {
		unforce_rtp_proxy();
	}
#!endif
 
	if (t_is_canceled()) {
		exit;
	}
 
	# uncomment the following lines if you want to block client 
	# redirect based on 3xx replies.
	##if (t_check_status("3[0-9][0-9]")) {
	##t_reply("404","Not found");
	##	exit;
	##}
 
	# uncomment the following lines if you want to redirect the failed 
	# calls to a different new destination
	##if (t_check_status("486|408")) {
	##	sethostport("192.168.2.100:5060");
	##	append_branch();
	##	# do not set the missed call flag again
	##	t_relay();
	##}
}
 
 
#!ifdef WITH_XCAPSRV
#!define WITH_XHTTPAUTH
event_route[xhttp:request] {
	xdbg("===== xhttp: request [$rv] $rm => $hu\n");
#!ifdef WITH_XHTTPAUTH
	if (!www_authorize("xcap", "subscriber"))
	{
		www_challenge("xcap", "0");
		exit;
	}
#!endif
	if($hu=~"^/xcap-root/")
	{
		set_reply_close();
		set_reply_no_connect();
		# xcap ops
		$xcapuri(u=>data) = $hu;
		if($xcapuri(u=>xuid)=~"^sip:.+@.+")
			$var(uri) = $xcapuri(u=>xuid);
		else if($xcapuri(u=>xuid)=~".+@.+")
			$var(uri) = "sip:" + $xcapuri(u=>xuid);
		else
			$var(uri) = "sip:"+ $xcapuri(u=>xuid) + "@" + $Ri;
		xlog("===== xhttp: $xcapuri(u=>auid) : $xcapuri(u=>xuid)\n");
		if($xcapuri(u=>auid)=="xcap-caps")
		{
			$var(xbody) =
"<?xml version='1.0' encoding='UTF-8'?>
<xcap-caps xmlns='urn:ietf:params:xml:ns:xcap-caps'>
  <auids>
    <auid>rls-services</auid>
    <auid>pidf-manipulation</auid>
    <auid>xcap-caps</auid>
    <auid>resource-lists</auid>
    <auid>pres-rules</auid>
    <auid>org.openmobilealliance.pres-rules</auid>
  </auids>
  <extensions>
  </extensions>
  <namespaces>
    <namespace>urn:ietf:params:xml:ns:rls-services</namespace>
    <namespace>urn:ietf:params:xml:ns:pidf</namespace>
    <namespace>urn:ietf:params:xml:ns:xcap-caps</namespace>
    <namespace>urn:ietf:params:xml:ns:resource-lists</namespace>
    <namespace>urn:ietf:params:xml:ns:pres-rules</namespace>
  </namespaces>
</xcap-caps>";
			xhttp_reply("200", "ok", "application/xcap-caps+xml",
					"$var(xbody)");
			exit;
		}
#!ifdef WITH_XHTTPAUTH
        # be sure auth user access only its documents
        if ($au!=$(var(uri){uri.user})) {
            xhttp_reply("403", "Forbidden", "text/html",
                    "<html><body>$si:$sp</body></html>");
            exit;
        }
 
#!endif
		switch($rm) {
			case "PUT":
				xcaps_put("$var(uri)", "$hu", "$rb");
				if($xcapuri(u=>auid)=~"pres-rules")
				{
					xlog("===== xhttp put: refreshing watchers for $var(uri)\n");
					pres_update_watchers("$var(uri)", "presence");
					pres_refresh_watchers("$var(uri)", "presence", 1);
				}
				exit;
			break;
			case "GET":
				xlog("===== xhttp: get $var(uri) => $hu\n");
				xcaps_get("$var(uri)", "$hu");
				exit;
			break;
			case "DELETE":
				xcaps_del("$var(uri)", "$hu");
				if($xcapuri(u=>auid)=~"pres-rules")
				{
					xlog("===== xhttp del: refreshing watchers for $var(uri)\n");
					pres_update_watchers("$var(uri)", "presence");
					pres_refresh_watchers("$var(uri)", "presence", 1);
				}
				exit;
			break;
		}
	}
 
	# http ops
	xhttp_reply("200", "ok", "text/html",
					"<html><body>OK: $si:$sp</body></html>");
	exit;
}
#!endif

Remember that any change in configuration file requires to restart Kamailio SIP server, therefore be sure you do it after replacing the config file with above content.

Config Remarks

  • config file is based on default config file coming with 3.1.0 at this time, you can easily do a diff with stock default config to see the changes
  • SIMPLE presence features are enabled by #!define WITH_PRESENCE - in addition, user authentication and persistent user location were enabled using as backend a MySQL server
  • xcap server features are enabled by #!define WITH_XCAPSRV - just search for WITH_XCAPSRV token to discover the parts related to xcap server functionality

Regarding the XCAP server configuration, main part is in event_route[xhttp:request]. Digest authentication is enable so that only local subscribers can do XCAP operations. You can tighten the security by being sure the user in XCAP URL is the same as authentication user, avoiding identity stealing.

Besides using the xhttp and xcap_server modules in your config, another important setting is 

tcp_accept_no_cl=yes

Without it Kamailio is rejecting requests without content-lenght (a requirement in SIP over TCP but optional in HTTP).

A big chunk of XCAP's event_route is building the reply for XCAP capabilities query (xcap-caps): the assignment of $var(xbody). Maybe in the future will be moved in C code, but having it in config offers a very convenient way to add/remove auids as you decide to support or not some of those XCAP extensions.

SIP Communicator Installation

You can download latest version for your OS at:

Configuration is easy via GUI. Starting SIP Communicator without a SIP account setup and no registration will indicate the state 'offline'.

Select “Add a new account” and fill SIP account details.

Click on “Advanced” to setup Presence and XCAP. Note the XCAP server URI - it must be set to Kamailio's IP (or domain) on port 5060. If you use TLS, then you can set the protocol to https and port 5061.

Click next to see the summary of configuration and then sign in.

After signing in, you can notice the status changed to 'onine'.

Now you can add contacts (you can right-click on buddy list panel). Select the SIP account for that contact, then choose the group and set the SIP ID.

The new contact will appear offline until it will add you in its contact list (specific to this particular version of SIP Communicator).

Use a second SIP Communicator instance to setup second SIP account, following the steps above and add first account as contact. You can see in next image Alice on left, with Mac OS X, and Bob on right, with Ubuntu. When both instances are setup, each will see the other being 'online'.

As soon as you change the state in one SIP Communicator instance, it will become visible on the other instance. In next image, Bob sets the status to 'Away', the icon on Alice's instance changing to show that.

Updates in Kamailio DB

Several screenshots taken with SIREMIS show what was stored in Kamailio database. With Siremis 2.0, 'Presence Services' menu offers the options to view Presence and XCAP database.

The Wachers list is showing who is watching who - what users subscribed to presence states of other users.

The Active Watchers list shows who has an active subscription - it is online, waiting for presence status notifications coming from its contacts.

In Presentity list you can view what users published states. In this case, Alice published that she is online.

XCAP list allow access to XCAP documents stored by users on XCAP server. There are two kind of documents in this case: presence rules and resource lists (contact lists).

A detailed look at resource-lists document for user Alice shows that she has Bob in her contact list.

A detailed look at pres-rules document for user Alice shows that she has allowed Bob to see her presence status.

Additional Tools

There are more SIP clients implementing SIMPLE Presence extensions than XCAP support. The option is to either offer a web management interface where users can accept people willing to see their status. Also, Kamailio presence module can accept new watchers globally via 'force_active' parameter.

Besides these two options, an alternative is to use command line tools. A very handy is curl, an application which is very portable and spread across distributions.

For example, fetching the buddy list for user Alice: 

# curl --digest -u alice:alice123 \
       http://192.168.178.23:5060/xcap-root/resource-lists/users/sip:alice@192.168.178.23/index

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<resource-lists xmlns="urn:ietf:params:xml:ns:resource-lists">
<list name="RootGroup">
<entry uri="sip:bob@192.168.178.23">
<display-name>bob</display-name>
</entry>
</list>
</resource-lists>

You can save the result in a file, say buddylist.xml, do any changes you want and then you can upload back with: 

# curl --digest -u alice:alice123 -T buddylist.xml -X PUT \
       http://192.168.178.23:5060/xcap-root/resource-lists/users/sip:alice@192.168.178.23/index

Deleting the buddy list document from XCAP server can be done with: 

# curl --digest -u alice:alice123 -X DELETE \
       http://192.168.178.23:5060/xcap-root/resource-lists/users/sip:alice@192.168.178.23/index

Similar operations can be done over presence rules document, by using the proper URL: 

# curl --digest -u alice:alice123 \
       http://192.168.178.23:5060/xcap-root/pres-rules/users/sip:alice@192.168.178.23/presrules

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<ruleset xmlns="urn:ietf:params:xml:ns:common-policy">
<rule id="sip_communicator">
<conditions>
<identity>
<one id="sip:bob@192.168.178.23"/>
</identity>
</conditions>
<actions>
<sub-handling xmlns="urn:ietf:params:xml:ns:pres-rules">allow</sub-handling>
</actions>
<transformations>
<provide-devices xmlns="urn:ietf:params:xml:ns:pres-rules">
<all-devices/>
</provide-devices>
<provide-persons xmlns="urn:ietf:params:xml:ns:pres-rules">
<all-persons/>
</provide-persons>
<provide-services xmlns="urn:ietf:params:xml:ns:pres-rules">
<all-services/>
</provide-services>
</transformations>
</rule>
</ruleset>

Conclusions

  • turning Kamailio in an XCAP server is only a matter of configuration (less than 100 lines of configuration, most of them compacted in an event_route, handling authentication as well and XCAP capability reply). XCAP configuration part is not mixed with SIP routing part (btw, you can even use include_file directive if you want to keep separate file for XCAP's event_route).
  • handling XCAP over either HTTP, HTTPS or SIP is trivial, it is your choice. It is no need for a dedicated HTTP server.
  • presence server and xcap server are now in the same application instance, therefore tightly integrated
  • Kamailio can be used as a standalone XCAP server without problems, allowing other SIP servers to use it in this scope
  • you can configure Kamailio to listen on port 80 (or 443) just by adding port=80 in the configuration file

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