XCAP Server Module

Daniel-Constantin Mierla

   <miconda@gmail.com>

Edited by

Daniel-Constantin Mierla

   <miconda@gmail.com>

   Copyright © 2010 asipto.com
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications

        3. Parameters

              3.1. db_url (string)
              3.2. xcap_table (string)
              3.3. xcap_root (str)
              3.4. buf_size (int)
              3.5. xml_ns (str)
              3.6. directory_scheme (int)
              3.7. directory_hostname (string)

        4. Functions

              4.1. xcaps_put(uri, path, doc)
              4.2. xcaps_get(uri, path)
              4.3. xcaps_del(uri, path)

        5. Pseudo Variables
        6. Simple XCAP Server Config

   List of Examples

   1.1. Set the “db_url” parameter
   1.2. Set the “xcap_table” parameter
   1.3. Set xcap_root parameter
   1.4. Set the “buf_size” parameter
   1.5. Set xml_ns parameter
   1.6. Set directory_scheme parameter
   1.7. Set directory_hostname parameter
   1.8. xcaps_put usage
   1.9. xcaps_get usage
   1.10. xcaps_del usage
   1.11. $xcapuri(...) PV
   1.12. sample xcap server

Chapter 1. Admin Guide

   Table of Contents

   1. Overview
   2. Dependencies

        2.1. Kamailio Modules
        2.2. External Libraries or Applications

   3. Parameters

        3.1. db_url (string)
        3.2. xcap_table (string)
        3.3. xcap_root (str)
        3.4. buf_size (int)
        3.5. xml_ns (str)
        3.6. directory_scheme (int)
        3.7. directory_hostname (string)

   4. Functions

        4.1. xcaps_put(uri, path, doc)
        4.2. xcaps_get(uri, path)
        4.3. xcaps_del(uri, path)

   5. Pseudo Variables
   6. Simple XCAP Server Config

1. Overview

   This module provides an XCAP server functionally inside Kamailio and
   SER SIP servers.

   Benefits brought by this integrated XCAP server:
     * reuse of SIP router transport layer - XCAP documents can be sent
       via SIP (UDP, TCP, TLS and SCTP) and via HTTP (TCP or TLS (HTTPS)).
       For HTTP/S, you need to load XHTTP module to handle HTTP/S
       requests.
     * the Presence server has access immediately to the latest version of
       XCAP documents. No more need to trigger refresh of XCAP documents
       via RPC command.
     * can be used stand-alone, with a different Presence server. It is
       not specific for Kamailio or SER. Documents can be fetched via GET
     * no exotic dependencies, it is written in C. It depends on libxml2,
       sl module and a database module (required to store the xcap
       documents).
     * you can do digest authentication using database, radius, ldap, etc.
       Can reuse authorization mechanisms provided by SIP server.
     * flexibility - the XCAP server is controlled from config file of SIP
       server, therefore you can blend the XCAP logic with features
       provided by core or other modules.

   Important: be sure you have global parameter: 'tcp_accept_no_cl=yes'.

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:
     * sl - stateless reply module
     * db - a database engine module
     * xhttp - embedded HTTP server if you want to get XCAP documents via
       HTTP.

2.2. External Libraries or Applications

   The following libraries or applications must be installed before
   running Kamailio with this module loaded:
     * libxml2 - libxml2 library for runtime and libxml2-dev for
       compilation.

3. Parameters

   3.1. db_url (string)
   3.2. xcap_table (string)
   3.3. xcap_root (str)
   3.4. buf_size (int)
   3.5. xml_ns (str)
   3.6. directory_scheme (int)
   3.7. directory_hostname (string)

3.1. db_url (string)

   Database URL.

   Default value is “mysql://kamailio:kamailiorw@localhost/kamailio”.

   Example 1.1. Set the “db_url” parameter
...
modparam("xcap_server", "db_url", "mysql://user:passwd@host.com/dbname")
...

3.2. xcap_table (string)

   The name of table where to store the xcap documents.

   Default value is “xcap”.

   Example 1.2. Set the “xcap_table” parameter
...
modparam("xcap_server", "xcap_table", "xcapdocs")
...

3.3. xcap_root (str)

   XCAP root URL.

   Default value is '/xcap-root/'.

   Example 1.3. Set xcap_root parameter
...
modparam("xcap_server", "xcap_root", "/xcap-root/")
...

3.4. buf_size (int)

   Size of local buffer for handling XCAP documents.

   Default value is “1024”.

   Example 1.4. Set the “buf_size” parameter
...
modparam("xcap_server", "buf_size", 2048)
...

3.5. xml_ns (str)

   Register extra XML namespaces to be used with XPath. You can set the
   parameter many times to add more namespaces. The format is
   'prefix=href'.

   Default value is 'null'.

   Example 1.5. Set xml_ns parameter
...
modparam("xcap_server", "xml_ns",
    "rl=urn:ietf:params:xml:ns:resource-lists")
modparam("xcap_server", "xml_ns",
    "my=urn:my:prefix")
...

3.6. directory_scheme (int)

   Allows the scheme used in org.openmobilealliance.xcap-directory
   listings to be set to a specific value.

   The URLs in an org.oma.xcap-directory listing must be be paths a client
   can use to download the listed XCAP documents. In some cases (for
   example, when the XCAP server is accessed using HTTP from an HTTP proxy
   the client connected to using HTTPS) the XCAP server may not be able to
   automatically determine the correct scheme to use based on the HTTP
   connection.
     * -1 (default) - determine scheme automatically. HTTP for TCP
       connections and HTTPS for TLS connections.
     * 0 - use the HTTP scheme.
     * 1 - use the HTTPS scheme.

   Example 1.6. Set directory_scheme parameter
...
modparam("xcap_server", "directory_scheme", 0)
...

3.7. directory_hostname (string)

   Allows the hostname (and port) used in
   org.openmobilealliance.xcap-directory listings to be set to a specific
   value.

   The URLs in an org.oma.xcap-directory listing must be be paths a client
   can use to download the listed XCAP documents. In some cases (for
   example, when the XCAP server is accessed through a proxy that
   re-writes headers, or a client is non-conforming and does not include a
   Host: header) the XCAP server may not be able to automatically
   determine the correct hostname to use.

   When this parameter is not set the XCAP server will attempt to use the
   contents of the (mandatory) Host: header. If the Host: header is not
   present the XCAP server will use the IP address and port the XCAP
   request was received on.

   Example 1.7. Set directory_hostname parameter
...
modparam("xcap_server", "directory_hostname", "xcap.example.com")
...

4. Functions

   4.1. xcaps_put(uri, path, doc)
   4.2. xcaps_get(uri, path)
   4.3. xcaps_del(uri, path)

4.1.  xcaps_put(uri, path, doc)

   Handle XCAP PUT command.

   Example 1.8. xcaps_put usage
...
event_route[xhttp:request] {
        if($hu=~"^/xcap-root/")
        {
                # xcap ops
                switch($rm) {
                        case "PUT":
                                xcaps_put("sip:101@$Ri", "$hu", "$rb");
                                exit;
                                break;
                }
        }
}
...

4.2.  xcaps_get(uri, path)

   Handle XCAP GET command.

   Example 1.9. xcaps_get usage
...
event_route[xhttp:request] {
        if($hu=~"^/xcap-root/")
        {
                # xcap ops
                switch($rm) {
                        case "GETT":
                                xcaps_get("sip:101@$Ri", "$hu");
                                exit;
                                break;
                }
        }
}
...

4.3.  xcaps_del(uri, path)

   Handle XCAP DELETE command.

   Example 1.10. xcaps_del usage
...
event_route[xhttp:request] {
        if($hu=~"^/xcap-root/")
        {
                # xcap ops
                switch($rm) {
                        case "DELETE":
                                xcaps_del("sip:101@$Ri", "$hu");
                                exit;
                                break;
                }
        }
}
...

5. Pseudo Variables

     * $xcapuri(name=>key) - name can be any to idenitfy the XCAP uri; key
       can be: data, uri, root, auid, type, tree, xuid, file, node,
       target, domain, uri_adoc.

   Exported pseudo-variables are documented at
   https://www.kamailio.org/wiki/.

   Example 1.11. $xcapuri(...) PV
...
    $xcapuri(u=>data) = $hu;
    xdbg("SCRIPT: xcap service $xcapuri(u=>auid) for $xcapuri(u=>xuid)\n");
...

6. Simple XCAP Server Config

   Example 1.12. sample xcap server
...
tcp_accept_no_cl=yes
...
loadmodule "xhttp.so"
loadmodule "xcap_server.so"

...

# ----- xcap_server params -----
modparam("xcap_server", "db_url",
        "mysql://kamailio:kamailiorw@localhost/kamailio")

...

event_route[xhttp:request] {
    if (!www_authorize("xcap", "subscriber"))
    {
        www_challenge("xcap", "0");
        exit;
    }
    if($hu=~"^/xcap-root/")
    {
        set_reply_close();
        set_reply_no_connect();
        # xcap ops - break down http uri to get xcap user id
        $xcapuri(u=>data) = $hu;
        if($xcapuri(u=>xuid)=~"^sip:.+@.+")
            $var(uri) = $xcapuri(u=>xuid);
        else
            $var(uri) = "sip:"+ $xcapuri(u=>xuid) + "@" + $Ri;

        # handle XCAP capability request
        if($xcapuri(u=>auid)=="xcap-caps")
        {
            if ($rm == "GET")
            {
                $var(xbody) =
"<?xml version='1.0' encoding='UTF-8'?>
<xcap-caps xmlns='urn:ietf:params:xml:ns:xcap-caps'>
  <auids>
    <auid>rls-services</auid>
    <auid>pidf-manipulation</auid>
    <auid>xcap-caps</auid>
    <auid>resource-lists</auid>
    <auid>pres-rules</auid>
    <auid>org.openmobilealliance.pres-rules</auid>
    <auid>org.openmobilealliance.user-profile</auid>
    <auid>org.openmobilealliance.pres-content</auid>
    <auid>org.openmobilealliance.search</auid>
    <auid>org.openmobilealliance.xcap-directory</auid>
  </auids>
  <extensions>
  </extensions>
  <namespaces>
    <namespace>urn:ietf:params:xml:ns:rls-services</namespace>
    <namespace>urn:ietf:params:xml:ns:pidf</namespace>
    <namespace>urn:ietf:params:xml:ns:xcap-caps</namespace>
    <namespace>urn:ietf:params:xml:ns:resource-lists</namespace>
    <namespace>urn:ietf:params:xml:ns:pres-rules</namespace>
    <namespace>urn:oma:xml:xdm:user-profile</namespace>
    <namespace>urn:oma:xml:prs:pres-content</namespace>
    <namespace>urn:oma:xml:xdm:search</namespace>
    <namespace>urn:oma:xml:xdm:xcap-directory</namespace>
  </namespaces>
</xcap-caps>";
                xhttp_reply("200", "ok", "application/xcap-caps+xml",
                            "$var(xbody)");
            }
            else
            {
                append_to_reply("Allow: GET\r\n");
                xhttp_reply("405", "Method Not Allowed", "", "");
            }
            exit;
        }
        # be sure auth user access only its documents
        if ($au!=$(var(uri){uri.user})) {
            xhttp_reply("403", "Forbidden", "text/html",
                    "operation not allowed");
            exit;
        }

        xdbg("SCRIPT: xcap service $xcapuri(u=>auid) for $xcapuri(u=>xuid)\n");
        switch($rm) {
            case "PUT":
                xcaps_put("$var(uri)", "$hu", "$rb");
                if($xcapuri(u=>auid)=~"pres-rules")
                {
                    pres_update_watchers("$var(uri)", "presence");
                    pres_refresh_watchers("$var(uri)", "presence", 1);
                }
                else if($xcapuri(u=>auid)=~"rls-services"
                        || $xcapuri(u=>auid)=~"resource-lists")
                {
                    rls_update_subs("$var(uri)", "presence");
                }
                else if($xcapuri(u=>auid)=~"pidf-manipulation")
                {
                    pres_refresh_watchers("$var(uri)", "presence", 2,
                                            "$xcapuri(u=>uri_adoc)",
                                            "$xcapuri(u=>file)");
                }
                exit;
            break;
            case "GET":
                xcaps_get("$var(uri)", "$hu");
                exit;
            break;
            case "DELETE":
                xcaps_del("$var(uri)", "$hu");
                if($xcapuri(u=>auid)=~"pres-rules")
                {
                    pres_update_watchers("$var(uri)", "presence");
                    pres_refresh_watchers("$var(uri)", "presence", 1);
                }
                else if($xcapuri(u=>auid)=~"rls-services"
                        || $xcapuri(u=>auid)=~"resource-lists")
                {
                    rls_update_subs("$var(uri)", "presence");
                }
                else if($xcapuri(u=>auid)=~"pidf-manipulation")
                {
                    pres_refresh_watchers("$var(uri)", "presence", 2,
                                            "$xcapuri(u=>uri_adoc)",
                                            "$xcapuri(u=>file)");
                }
                exit;
            break;
            case "POST":
                if($xcapuri(u=>auid)=~"search")
                {
                    xhttp_reply("501", "Not Implemented", "", "");
                }
                else
                {
                    if($xcapuri(u=>auid)=~"xcap-directory")
                    {
                        append_to_reply("Allow: GET\r\n");
                    }
                    else
                    {
                        append_to_reply("Allow: DELETE, GET, PUT\r\n");
                    }
                    xhttp_reply("405", "Method Not Allowed", "", "");
                }
                exit;
            break;
        }
    }

    # other http requests
    xhttp_reply("404", "Not Found", "", "");
    exit;
}
...

   The URL for XCAP has to be:

   http://_your_sip_server_ip_:_your_sip_server_port_/xcap-root/...

   For example, if your SIP server IP is 10.1.1.10 and it is listening on
   TCP port 5060 and TLS port 5061, following XCAP URLs can be used:

   http://10.1.1.10:5060/xcap-root/...

   https://10.1.1.10:5061/xcap-root/...
