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kamailio/modules/msrp/doc/msrp_admin.xml

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<?xml version="1.0" encoding='ISO-8859-1'?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
<!-- Include general documentation entities -->
<!ENTITY % docentities SYSTEM "../../../docbook/entities.xml">
%docentities;
]>
<!-- Module User's Guide -->
<chapter>
<title>&adminguide;</title>
<section>
<title>Overview</title>
<para>
This module provides a MSRP routing engine, a.k.a. MSRP relay.
MSRP (Message Session Relay Protocol) is defined by RFC4975,
and the extensions for an MSRP relay are covered in RFC4976.
</para>
<para>
A typical use of MSRP is instant messaging sessions initiated
via SIP. Unlike page-mode instant messaging, which is done via the SIP
MESSAGE request, MSRP uses a different communication channel which
is negotiated via INVITE-200 OK-ACK.
</para>
<para>
However, MSRP is still a text-based protocol. It uses several routing
mechanisms similar to what exists in SIP. Furthermore,
MSRP requres TCP, and recommends TLS for confidentiality and security.
In light of the scalability and performance of &kamailio; in handling
TCP/TLS, this module reuses &kamailio;'s core framework to
offer MSRP routing capabilities. Along with embedded Presence and XCAP
servers, &kamailio; offers now a complete solution for SIP beyond VoIP.
</para>
<para>
One of the main benefits of this module is the ability to reuse
all the other extensions that exist in the SIP server, including
accounting, authentication, authorization to database connectors,
security and DoS attack protections.
</para>
<para>
&kamailio; can handle SIP and MSRP traffic received on the same port;
the appropriate configuration file block being executed based on the
type of message. Therefore, you can use &kamailio; as a stand-alone
MSRP relay or you can have an instance handling both SIP and MSRP. Another
option is to configure &kamailio; to listen on multiple ports, some
of them for SIP and others for MSRP.
</para>
</section>
<section>
<title>Dependencies</title>
<section>
<title>&kamailio; Modules</title>
<para>
The following modules must be loaded before this module:
<itemizedlist>
<listitem>
<para>
<emphasis>None</emphasis>.
</para>
</listitem>
</itemizedlist>
</para>
</section>
<section>
<title>External Libraries or Applications</title>
<para>
The following libraries or applications must be installed before running
&kamailio; with this module loaded:
<itemizedlist>
<listitem>
<para>
<emphasis>None</emphasis>
</para>
</listitem>
</itemizedlist>
</para>
</section>
</section>
<section>
<title>Parameters</title>
<section>
<title><varname>sipmsg</varname> (int)</title>
<para>
If 1, the module will build a SIP message from MSRP frame headers,
providing it to event_route[msrp:frame-in]. All the config
file functions (apart from SIP request relay) that can be used
in a request route block can be used in msrp event_route.
</para>
<para>
<emphasis>
Default value is '1'.
</emphasis>
</para>
<example>
<title>Set <varname>sipmsg</varname> parameter</title>
<programlisting format="linespecific">
...
modparam("msrp", "sipmsg", 1)
...
</programlisting>
</example>
</section>
</section>
<section>
<title>Functions</title>
<section>
<title>
<function moreinfo="none">msrp_relay()</function>
</title>
<para>
Relay MSRP frame according to the To-Path. This function has to be
executed for each MSRP request or reply that has to be forwarded. Note
that due to nature of MSRP transport layer, which is reliable
(TCP/TLS), there is no retransmission of MSRP frames.
</para>
<para>
This function can be used in ANY_ROUTE.
</para>
<example>
<title><function>msrp</function> usage</title>
<programlisting format="linespecific">
...
event_route[msrp:frame-in] {
msrp_relay();
}
...
</programlisting>
</example>
</section>
<section>
<title>
<function moreinfo="none">msrp_reply(code, text [, hdrs])</function>
</title>
<para>
Send a reply for the current MSRP request, adding optional headers.
</para>
<para>
The parameter can be a pseudo-variable.
</para>
<para>
This function can be used in ANY_ROUTE.
</para>
<example>
<title><function>msrp_reply</function> usage</title>
<programlisting format="linespecific">
...
event_route[msrp:frame-in] {
msrp_reply("403", "Not allowed");
}
...
</programlisting>
</example>
</section>
<section>
<title>
<function moreinfo="none">msrp_is_request()</function>
</title>
<para>
Return true if the MSRP frame is a request.
</para>
<para>
This function can be used in ANY_ROUTE.
</para>
<example>
<title><function>msrp_is_request</function> usage</title>
<programlisting format="linespecific">
...
event_route[msrp:frame-in] {
if(msrp_is_request())
{
msrp_relay();
exit;
}
}
...
</programlisting>
</example>
</section>
<section>
<title>
<function moreinfo="none">msrp_is_reply()</function>
</title>
<para>
Return true if the MSRP frame is a reply.
</para>
<para>
This function can be used in ANY_ROUTE.
</para>
<example>
<title><function>msrp_is_reply</function> usage</title>
<programlisting format="linespecific">
...
event_route[msrp:frame-in] {
if(msrp_is_reply())
{
msrp_relay();
exit;
}
}
...
</programlisting>
</example>
</section>
<section>
<title>
<function moreinfo="none">msrp_set_dst(addr, sock)</function>
</title>
<para>
Set destination attributes: addr - target address as MSRP URI;
sock - local socket to be used (format 'proto:ip:port').
</para>
<para>
The parameter can be a pseudo-variable.
</para>
<para>
This function can be used in ANY_ROUTE.
</para>
<example>
<title><function>msrp_set_dst</function> usage</title>
<programlisting format="linespecific">
...
event_route[msrp:frame-in] {
...
msrp_set_dst("msrp://127.0.0.1:8000", "tcp:127.0.0.1:5060");
...
}
...
</programlisting>
</example>
</section>
<section>
<title>
<function moreinfo="none">msrp_relay_flags(flags)</function>
</title>
<para>
Set transport layer sending flags for forwarding current MSRP frame;
flags - a bitmask of flags - 1 (don't create a new connection), 2
(close connection after send).
</para>
<para>
The parameter can be a pseudo-variable.
</para>
<para>
This function can be used in ANY_ROUTE.
</para>
<example>
<title><function>msrp_relay_flags</function> usage</title>
<programlisting format="linespecific">
...
event_route[msrp:frame-in] {
...
msrp_relay_flags("1");
...
}
...
</programlisting>
</example>
</section>
<section>
<title>
<function moreinfo="none">msrp_reply_flags(flags)</function>
</title>
<para>
Set transport layer sending flags for replies to the current MSRP frame;
flags - a bitmask of flags - 1 (don't create a new connection),
2 (close connection after send).
</para>
<para>
The parameter can be a pseudo-variable.
</para>
<para>
This function can be used in ANY_ROUTE.
</para>
<example>
<title><function>msrp_reply_flags</function> usage</title>
<programlisting format="linespecific">
...
event_route[msrp:frame-in] {
...
msrp_reply_flags("1");
...
}
...
</programlisting>
</example>
</section>
</section>
<section>
<title>Pseudo Variables</title>
<para>
The module exports a pseudo-variable class, $msrp(key), to access
the MSRP frame (e.g. first line attributes, body, all frame
content).
</para>
<para>
The module exports a transformations class, 'msrpuri', to allow
access attributes of a MSRP URI.
</para>
<para>
These are documented in the appropriate Wiki pages hosted on the
project web site.
</para>
</section>
<section>
<title>Event Routes</title>
<para>
For each MSRP frame received from the network, the module executes
event_route[msrp:frame-in] block in the config file.
</para>
</section>
<section>
<title>Usage</title>
<para>
When 'sipmsg' parameter is set to 1 (which is default), the module
internally builds a SIP request from the MSRP frame and exposes it to
the config file interpreter. This way, all the functions that are
valid for SIP requests can be used safely in event_route[msrp:frame-in].
</para>
<para>
To build the SIP request, the module takes the first line and the
headers from an MSRP message and appends them to a static buffer. The
next two examples show an MSRP frame and the resulting SIP request.
</para>
<programlisting format="linespecific">
<![CDATA[
...
MSRP 6aef SEND
To-Path: msrps://a.example.org:9000/kjfjan;tcp \
msrps://b.example.net:9000/aeiug;tcp \
msrps://bob.example.net:8145/foo;tcp
From-Path: msrps://alice.example.org:7965/bar;tcp
Success-Report: yes
Byte-Range: 1-*/*
Message-ID: 87652
Content-Type: text/plain
Hi Bob, I'm about to send you a photo.
-------6aef$
...
]]>
</programlisting>
<programlisting format="linespecific">
<![CDATA[
...
MSRP sip:a@127.0.0.1 SIP/2.0
Via: SIP/2.0/UDP 127.0.0.1:9;branch=z9hG4bKa
From: <b@127.0.0.1>;tag=a
To: <a@127.0.0.1>
Call-ID: a
CSeq: 1 MSRP
Content-Length: 0
MSRP-First-Line: MSRP 6aef SEND
To-Path: msrps://a.example.org:9000/kjfjan;tcp \
msrps://b.example.net:9000/aeiug;tcp \
msrps://bob.example.net:8145/foo;tcp
From-Path: msrps://alice.example.org:7965/bar;tcp
Success-Report: yes
Byte-Range: 1-*/*
Message-ID: 87652
Content-Type: text/plain
...
]]>
</programlisting>
<para>
Note that MSRP does not permit line folding. A "\" in the examples
shows a line continuation due to the limitations of line length of this
document. Neither the backslash nor the extra CRLF is included in
the actual request or response.
</para>
<para>
As can be observed, the MSRP frame content starts with the body
of the 'MSRP-First-Line:' header. Using static content to get to a
valid SIP request is a perfect trade-off for performance.
</para>
<para>
Besides the option to access parts of MSRP frame via an
internally-built SIP message, the module exports a new pseudo-variable
class $msrp(key) which returns attributes from the MSRP frame. There is
also a new transformation, {msrpuri.key}, to get access to parts
of an MSRP URI. See the appropriate Wiki pages on the project's
web site for full details about new pseudo-variable and
transformation classes.
</para>
<para>
Next is an example of configuration file with the routing block
for MSRP frames. In this config, the SIP traffic is rejected.
</para>
<example>
<title>Event Route</title>
<programlisting format="linespecific">
...
<![CDATA[
#!KAMAILIO
debug=2
memdbg=5
memlog=5
children=4
log_stderror=yes
auto_aliases=no
tcp_accept_no_cl=yes
tcp_connection_lifetime=1810
listen=127.0.0.1:5060
mpath="modules_k/:modules/"
loadmodule "sl.so"
loadmodule "kex.so"
loadmodule "mi_fifo.so"
loadmodule "ctl.so"
loadmodule "msrp.so"
loadmodule "pv.so"
loadmodule "auth.so"
loadmodule "cfgutils.so"
loadmodule "htable.so"
loadmodule "xlog.so"
# ----- mi_fifo params -----
modparam("mi_fifo", "fifo_name", "/tmp/kamailio_fifo")
modparam("htable", "htable", "c=>size=8;autoexpire=1800;")
request_route {
sl_send_reply("403", "No SIP Here");
exit;
}
reply_route {
drop;
}
event_route[msrp:frame-in] {
xdbg("============#[[$msrp(method)]]===========\n");
xdbg("============*[[$si:$sp]]\n");
xdbg("============ crthop: [$msrp(crthop)]\n");
xdbg("============ prevhop: [$msrp(prevhop)]\n");
xdbg("============ nexthop: [$msrp(nexthop)]\n");
xdbg("============ firsthop: [$msrp(firsthop)]\n");
xdbg("============ lasthop: [$msrp(lasthop)]\n");
xdbg("============ prevhops: [$msrp(prevhops)]\n");
xdbg("============ nexthops: [$msrp(nexthops)]\n");
xdbg("============ srcaddr: [$msrp(srcaddr)]\n");
xdbg("============ srcsock: [$msrp(srcsock)]\n");
xdbg("============ sessid: [$msrp(sessid)]\n");
msrp_reply_flags("1");
if(msrp_is_reply())
{
msrp_relay();
exit;
}
# handle AUTH MSRP requests
if($msrp(method)=="AUTH")
{
if($msrp(nexthops)>0)
{
msrp_relay();
exit;
}
# frame for local server - send Use-Path
# -- passwd can be loaded from DB based on $au
$var(passwd) = "xyz123";
if(!pv_www_authenticate("myrealm", "$var(passwd)", "0"))
{
if(auth_get_www_authenticate("myrealm", "0",
"$var(wauth)"))
{
msrp_reply("401", "Authorization Required",
"$var(wauth)");
} else {
msrp_reply("500", "Server Error");
}
exit;
}
$var(cnt) = $var(cnt) + 1;
pv_printf("$var(sessid)", "s.$(pp).$(var(cnt)).$(RANDOM)");
$sht(msrp=>$var(sessid)::srcaddr) = $msrp(srcaddr);
$sht(msrp=>$var(sessid)::srcsock) = $msrp(srcsock);
# - Use-Path: the MSRP address for server + session id
$var(UsePath) = "Use-Path: msrp://127.0.0.1:5060/"
+ $var(sessid) + ";tcp\r\n";
msrp_reply("200", "OK", "$var(UsePath)");
exit;
}
if($msrp(method)=="SEND")
{
if($msrp(nexthops)>1)
{
msrp_reply("200", "Received");
msrp_relay();
exit;
}
$var(sessid) = $msrp(sessid);
if($sht(msrp=>$var(sessid)::srcaddr) == $null)
{
# one more hop, but we don't have address in htable
msrp_reply("481", "No Such Session");
exit;
}
msrp_relay_flags("1");
msrp_set_dst("$sht(msrp=>$var(sessid)::srcaddr)",
"$sht(msrp=>$var(sessid)::srcsock)");
msrp_relay();
exit;
}
msrp_relay();
}
]]>
...
</programlisting>
</example>
</section>
</chapter>