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<!-- Module User's Guide -->

<chapter>

	<title>&adminguide;</title>

	<section>
	<title>Overview</title>
	<para>
		This module offers topology hiding for INVITE-based dialogs, by stripping
		the SIP routing headers that show topology details .
		The script interpreter gets the SIP messages with full content,
		so all existing functionality is preserved.
	</para>
	<para>
		The module is transparent for the configuration writer. It only needs to be
		loaded (tune the module parameters if needed).
	</para>
	<para>
		It also works for SIP MESSAGE or other requests that do not create
		a dialog (e.g., OPTIONS) -- record_route() must be used for them as well,
		the headers are not going to be in the messages sent to the network, they
		are needed to know local addresses used to communicate with each side.
        This module is designed to work for presence (SUBSCRIBE-based) dialogs too.
	</para>
	<para>
		The REGISTER and PUBLISH requests are skipped from processing
		by this module, expected to be terminated on a local SIP server.
	</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>rr module</emphasis> - server must perform record
				routing to ensure in-dialog requests are encoded/decoded (it
				must be done for all initial requests).
			</para>
			</listitem>
			<listitem>
			<para>
				<emphasis>database module</emphasis> - to store the data
				for topology stripping and restoring.
			</para>
			</listitem>
			<listitem>
			<para>
				<emphasis>topoh module</emphasis> - in case of Call-ID mask
				for Call-ID masking.
			</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 id="topos.p.storage">
		<title><varname>storage</varname> (str)</title>
		<para>
		Type of storage, valid types are:
		</para>
		<itemizedlist>
		<listitem>
		<para>
			<emphasis>db</emphasis> - Database Backend
		</para>
		</listitem>
		<listitem>
		<para>
			<emphasis>redis</emphasis> - Redis Backend
		</para>
		</listitem>
		</itemizedlist>
		<para>
		<emphasis>
			Default value is <quote>db</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>storage</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "storage", "redis")
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.db_url">
		<title><varname>db_url</varname> (str)</title>
		<para>
		Database URL.
		</para>
		<para>
		<emphasis>
			Default value is <quote>&defaultdb;</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>db_url</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "db_url", "&exampledb;")
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.mask_callid">
		<title><varname>mask_callid</varname> (int)</title>
		<para>
			Whether to encode the Call-id: header. Some SIP extensions include
			the Call-id in the SIP message payload or header, so it is safe to
			not encode Call-id in such cases. Well-known extensions such as
			call transfer or conference join will be added to work with encoded
			Call-id.
			Topoh module should be loaded with use_mode paramerter set to 1
		</para>

		<para>
		<emphasis>
			Default value is 0 (do not mask).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>mask_callid</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "mask_callid", 1)
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.sanity_checks">
		<title><varname>sanity_checks</varname> (int)</title>
		<para>
			If set to 1, topos module will bind to sanity module in order
			to perform sanity checks over received SIP request. Default
			sanity checks are done. It is useful to check if received request
			is well formatted before proceeding to encoding/decoding.
		</para>
		<para>
		<emphasis>
			Default value is 0 (do not bind to sanity module).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>sanity_checks</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "sanity_checks", 1)
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.branch_expire">
		<title><varname>branch_expire</varname> (int)</title>
		<para>
			Interval in seconds after which the branch records are deleted.
		</para>
		<para>
		<emphasis>
			Default value is 180 (3 min).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>branch_expire</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "branch_expire", 300)
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.dialog_expire">
		<title><varname>dialog_expire</varname> (int)</title>
		<para>
			Interval in seconds after which the dialog records are deleted.
			Keep in mind that the module does not update the dialog timestamp
			after the initial call setup on re-INVITEs or other in-dialog
			messages. So set a large enough value (according your longest call
			duration) to prevent problems in re-writing messages.
			This key is only relevant for INVITE dialog.
                        SUBSCRIBE dialog records lifetime are based on value set in expires
                        header. Moreover each re-SUBSCRIBEs update the dialog timestamp.
		</para>
		<para>
		<emphasis>
			Default value is 10800 (3 hours).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>dialog_expire</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "dialog_expire", 3600)
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.clean_interval">
		<title><varname>clean_interval</varname> (int)</title>
		<para>
			Interval in seconds to run the clean up of stored
			records.
		</para>
		<para>
		<emphasis>
			Default value is 60 (1 min).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>clean_interval</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "clean_interval", 30)
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.event_callback">
		<title><varname>event_callback</varname> (str)</title>
		<para>
			The name of the function in the KEMI configuration file (embedded
			scripting language such as Lua, Python, ...) to be executed instead
			of event_route[...] blocks.
		</para>
		<para>
			The function receives a string parameter with the name of the event.
		</para>
		<para>
		<emphasis>
			Default value is 'empty' (no function is executed for events).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>event_callback</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "event_callback", "ksr_topos_event")
...
-- event callback function implemented in Lua
function ksr_topos_event(evname)
	KSR.info("===== topos module triggered event: " .. evname .. "\n");
	return 1;
end
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.event_mode">
		<title><varname>event_mode</varname> (int)</title>
		<para>
			Control what event_route blocks to be executed. It is a bitmask of:
			1 - execute event_route[topos:msg-outgoing]; 2 - execute
			event_route[topos:msg-sending]; 4 execute
			event_route[topos:msg-incoming]; 8 execute
			event_route[topos:msg-receiving];.
		</para>
		<para>
		<emphasis>
			Default value is 3 (execute both event_route blocks).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>event_mode</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "event_mode", 2)
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.contact_host">
		<title><varname>contact_host</varname> (str)</title>
		<para>
			You may need to control the host part of the Contact header added
			by topos. If the xavu_field_contact_host parameter is set, this value is
			ignored.

			For example when using TLS with TOPOS the remote UAS must be able to open
			a new TLS socket to the contact header.
			In this case, the contact header must contain a domain name with a trusted CA
			signed certitificate.
		</para>
		<para>
		<emphasis>
			Default value is taken from the Record-Route URI.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>contact_host</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "contact_host", "proxy.domain.com")
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.contact_mode">
		<title><varname>contact_mode</varname> (int)</title>
		<para>
		Control the mode where the key to lookup the message data from
		the database or redis server is stored. The default is to use
		the Contact user (0), alternatively a Contact URI parameter
		can be used (1) with values from the SIP message, or from AVP
		variables (2). This can be useful for interoperating which
		gateways that need a certain user part in the Contact URI.
		</para>
		<para>In mode (1) the a-side contact user is taken from the
		request URI and the b-side contact user from the Contact header
		of the processed initial SIP request.
		</para>
		<para>If you use the mode (2), you need to configure the
		<emphasis>xavu_field_a_contact</emphasis> and <emphasis>xavu_field_b_contact</emphasis>
		parameter. Furthermore you need to assign values to them during
		the processing of the initial SIP request.
		</para>
		<para>
		The name of the Contact URI parameter can be customized with
		the <emphasis>cparam_name</emphasis> parameter.
		</para>
		<para>
		<emphasis>
			Default value is 0 - use the Contact user
		</emphasis>
		</para>
		<example>
		<title>Set <varname>contact_mode</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "contact_mode", 1)
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.cparam_name">
		<title><varname>cparam_name</varname> (int)</title>
		<para>
		Name of the Contact URI parameter to store the database or
		redis server key for message lookup.
		</para>
		<para>
		This parameter is only used when the <emphasis>contact_mode</emphasis>
		parameter is set to <emphasis>1</emphasis> or <emphasis>2</emphasis>.
		</para>
		<para>
		<emphasis>
			Default value is <quote>tps</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>cparam_name</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "cparam_name", "xyz")
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.xavu_cfg">
		<title><varname>xavu_cfg</varname> (str)</title>
		<para>
			Name of root XAVU to hold config-specific values to be used by
			module at runtime.
		</para>
		<para>
			Note: this parameter must be set if any other parameter prefixed
			with `xavu_field_` is used.
		</para>
		<para>
		<emphasis>
			Default value is <quote>NULL</quote> (disabled).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>xavu_cfg</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "xavu_cfg", "_tps_")
modparam("topos", "xavu_field_a_contact", "a_contact")
...
    $xavu(_tps_=>a_contact) = "...";
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.xavu_field_a_contact">
		<title><varname>xavu_field_a_contact</varname> (str)</title>
		<para>
			Name of the field inside root XAVU specifed by `xavu_cfg`
			to evaluate for the A-side Contact Header user part. This parameter
			is only necessary in contact_mode (2).
		</para>
		<para>
		<emphasis>
			Default value is <quote>NULL</quote> (disabled).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>xavu_field_a_contact</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "xavu_cfg", "_tps_")
modparam("topos", "xavu_field_a_contact", "a_contact")
...
    $xavu(_tps_=>a_contact) = "...";
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.xavu_field_b_contact">
		<title><varname>xavu_field_b_contact</varname> (str)</title>
		<para>
			Name of the field inside root XAVU specifed by `xavu_cfg`
			to evaluate for the B-side Contact Header user part. This parameter
			is only necessary in contact_mode (2).
		</para>
		<para>
		<emphasis>
			Default value is <quote>NULL</quote> (disabled).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>xavu_field_b_contact</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "xavu_cfg", "_tps_")
modparam("topos", "xavu_field_b_contact", "b_contact")
...
    $xavu(_tps_=>b_contact) = "...";

...
</programlisting>
		</example>
	</section>
	<section id="topos.p.xavu_field_contact_host">
		<title><varname>xavu_field_contact_host</varname> (str)</title>
		<para>
			Control from where to take the host part of the Contact header added
			by topos. This parameter allows to take the value from an XAVU
			during run-time, it specifies the field inside XAVU "xavu_cfg".
			If this parameter is set, the contact_host parameter is ignored.

			For example when using TLS with TOPOS the remote UAS must be able to open
			a new TLS socket to the contact header.
			In this case, the contact header must contain a domain name with a trusted CA
			signed certitificate.
		</para>
		<para>
		<emphasis>
			Default value is empty, not set.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>xavu_field_contact_host</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "xavu_cfg", "_tps_")
modparam("topos", "xavu_field_contact_host", "contact_host")
...
    $xavu(_tps_=>contact_host) = "kamailio.org";
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.rr_update">
		<title><varname>rr_update</varname> (int)</title>
		<para>
			If set to 1, topos module will track and update record
			route changes on re-invite.
		</para>
		<para>
		<emphasis>
			Default value is 0 (do not update record route changes within dialog).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>rr_update</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "rr_update", 1)
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.context">
		<title><varname>context</varname> (str)</title>
		<para>
			Set the global context for topos instance.
		</para>
		<para>
			The value has to be maximum 12 characters.
		</para>
		<para>
		<emphasis>
			Default value is <quote>NULL</quote> (disabled).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>context</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "context", "srvone")
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.methods_nocontact">
		<title><varname>methods_nocontact</varname> (str)</title>
		<para>
			List of SIP methods to skip adding Contact header for.
		</para>
		<para>
		<emphasis>
			Default value is <quote>BYE,CANCEL,PRACK</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>methods_nocontact</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "methods_nocontact", "CANCEL,PRACK")
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.header_mode">
		<title><varname>header_mode</varname> (int)</title>
		<para>
			List of headers to disable multiple comma separated values inserted in compact form.
			Altough compact form is RFC compliant this paramter gives possibilty to disable
			compact form header values for UA that don't support or can't handle it.

			The following options are available:

			(1) - disable multiple comma separated values for Via header
			(2) - disable multiple comma separated values for Record-Route header
			(4) - disable multiple comma separated values for Route header

		</para>
		<para>
		<emphasis>
			Default value is <quote>0</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>header_mode</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "header_mode", 1)
...
</programlisting>
		</example>
	</section>
	<section id="topos.p.methods_noinitial">
		<title><varname>methods_noinitial</varname> (str)</title>
		<para>
			List of SIP methods to skip doing topos if it is an intial request
			(no To-tag).
		</para>
		<para>
		<emphasis>
			Default value is <quote></quote> (no method).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>methods_noinitial</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("topos", "methods_noinitial", "OPTIONS,NOTIFY")
...
</programlisting>
		</example>
	</section>
	</section>

	<section>
	<title>Functions</title>
	<section id="topos.f.tps_set_context">
		<title>
		<function moreinfo="none">tps_set_context(ctx)</function>
		</title>
		<para>
			Update the context at runtime. If the value is emtpy string, then
			the runtime context is reset.
		</para>
		<para>
		This function can be used from ANY_ROUTE.
		</para>
		<example>
		<title><function>tps_set_context</function> usage</title>
		<programlisting format="linespecific">
...
request_route {
    ...
    tps_set_context("srvone");
    ...
}
...
</programlisting>
		</example>
	</section>
	</section>

	<section>
	<title>Event Routes</title>
	<section id="topos.e.msg_outgoing">
		<title>event_route[topos:msg-outgoing]</title>
		<para>
		It is executed before doing topology stripping processing for an outgoing
		SIP message. If 'drop' is executed inside the event route, then the
		module skips doing the topology hiding.
		</para>
		<para>
		Inside the event route the variables $sndto(ip), $sndto(port) and
		$sndto(proto) point to the destination. The SIP message is not the one
		to be sent out, but an internally generated one at startup, to avoid
		reparsing the outgoing SIP message for the cases when topology hiding
		is not wanted.
		</para>
		<example>
		<title>Usage of event_route[topos:msg-outgoing]</title>
		<programlisting format="linespecific">
...
event_route[topos:msg-outgoing] {
  if($sndto(ip)=="10.1.1.10") {
    drop;
  }
}
...
</programlisting>
		</example>
	</section>
	<section id="topos.e.msg_sending">
		<title>event_route[topos:msg-sending]</title>
		<para>
		It is executed before doing topology stripping processing for a SIP
		message to be sent out, being executed after event_route[topos:msg-outgoing].
		</para>
		<para>
		Inside the event route the variables $sndto(ip), $sndto(port) and
		$sndto(proto) point to the destination. The SIP message is the one
		to be sent out.
		</para>
		<example>
		<title>Usage of event_route[topos:msg-sending]</title>
		<programlisting format="linespecific">
...
event_route[topos:msg-sending] {
  if(is_request() and $fU=="alice") {
    drop;
  }
}
...
</programlisting>
		</example>
	</section>
	<section id="topos.e.msg_incoming">
		<title>event_route[topos:msg-incoming]</title>
		<para>
		It is executed before doing topology stripping processing for an incoming
		SIP message. If 'drop' is executed inside the event route, then the
		module skips doing the topology hiding.
		</para>
		<para>
		Inside the event route the variables $si, $sp and
		$proto point to the source address. The SIP message is not the one
		to be sent out, but an internally generated one at startup, to avoid
		reparsing the outgoing SIP message for the cases when topology hiding
		is not wanted.
		</para>
		<example>
		<title>Usage of event_route[topos:msg-incoming]</title>
		<programlisting format="linespecific">
...
event_route[topos:msg-incoming] {
  if($si=="10.1.1.10") {
    drop;
  }
}
...
</programlisting>
		</example>
	</section>
	<section id="topos.e.msg_receiving">
		<title>event_route[topos:msg-receiving]</title>
		<para>
		It is executed before doing topology stripping processing for a SIP
		message that was received, being executed after event_route[topos:msg-incoing].
		</para>
		<para>
		Inside the event route the variables $si, $sp and
		$proto point to the source address. The SIP message is the one
		to be sent out.
		</para>
		<example>
		<title>Usage of event_route[topos:msg-receoving]</title>
		<programlisting format="linespecific">
...
event_route[topos:msg-receiving] {
  if(is_request() and $fU=="alice") {
    drop;
  }
}
...
</programlisting>
		</example>
	</section>
	</section>
</chapter>

