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

<chapter>
	<chapterinfo>
	<revhistory>
		<revision>
		<revnumber>$Revision: 1827 $</revnumber>
		<date>$Date: 2007-03-12 17:22:53 +0200 (Mon, 12 Mar 2007) $</date>
		</revision>
	</revhistory>
	</chapterinfo>
	<title>User's Guide</title>
	
	<section>
	<title>Overview</title>
	<para>The module contains REGISTER processing logic.</para>
	<section>
		<title>PATH support</title>
		<para>
		Register module includes Path support (according to RFC 3327) 
		for usage in registrars and home-proxies.
		</para>
		<para>
		A call to save(...) stores, if path-support is enabled
		in the registrar-module, the values of the Path
		Header(s) along with the contact into usrloc. There are
		three modes regarding the reply to a REGISTER including
		one or more Path HFs:
		</para>
		<itemizedlist>
			<listitem>
			<para>
				<emphasis>off</emphasis> - stores the value of the 
				Path headers into usrloc without passing it back to 
				the UAC in the reply.
			</para>
			</listitem>
			<listitem>
			<para>
				<emphasis>lazy</emphasis> - stores the Path header and 
				passes it back to the UAC if Path-support is indicated 
				by the <quote>path</quote> param in the Supported HF.
			</para>
			</listitem>
			<listitem>
			<para>
				<emphasis>strict</emphasis> - rejects the registration 
				with <quote>420 Bad Extension</quote> if there's a Path 
				header but no support for it is indicated by the UAC. 
				Otherwise it's stored and passed back to the UAC.
			</para>
			</listitem>
		</itemizedlist>
		<para>
		A call to lookup(...) always uses the path header if
		found, and inserts it as Route HF either in front of
		the first Route HF, or after the last Via HF if no
		Route is present. It also sets the destination uri to
		the first Path uri, thus overwriting the received-uri,
		because NAT has to be handled at the outbound-proxy of
		the UAC (the first hop after client's NAT).
		</para>
		<para>
		The whole process is transparent to the user, so no
		config changes are required beside setting the
		registrar-parameters <quote>use_path</quote> and 
		<quote>path_mode</quote>.
		</para>
	</section>
	</section>


	<section>
	<title>Dependencies</title>
	<section>
		<title>&ser; Modules</title>
		<para>
		The following modules must be loaded before this module:
			<itemizedlist>
			<listitem>
			<para>
				<emphasis>usrloc - User Location Module</emphasis>.
			</para>
			</listitem>
			<listitem>
			<para>
				<emphasis>sl - Stateless Replies</emphasis>.
			</para>
			</listitem>
			</itemizedlist>
		</para>
	</section>
	<section>
		<title>External Libraries or Applications</title>
		<para>
		The following libraries or applications must be installed before 
		running &ser; with this module loaded:
			<itemizedlist>
			<listitem>
			<para>
				<emphasis>None</emphasis>.
			</para>
			</listitem>
			</itemizedlist>
		</para>
	</section>
	</section>
	<section>
	<title>Exported Parameters</title>
	<section>
		<title><varname>default_expires</varname> (integer)</title>
		<para>
		If the processed message contains neither Expires 
		<acronym>HFs</acronym> nor expires contact parameters, this value 
		will be used for newly created usrloc records. The parameter contains 
		number of second to expire (for example use 3600 for one hour).
		</para>
		<para>
		<emphasis>
			Default value is 3600.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>default_expires</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "default_expires", 1800)
...
</programlisting>
		</example>
	</section>
	<section>
		<title><varname>min_expires</varname> (integer)</title>
		<para>
		The minimum expires value of a Contact, values lower than this 
		minimum will be automatically set to the minimum. Value 0 disables 
		the checking.
		</para>
		<para>
		<emphasis>
			Default value is 60.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>min_expires</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "min_expires", 60)
...
</programlisting>
		</example>
	</section>
	<section>
		<title><varname>max_expires</varname> (integer)</title>
		<para>
		The maximum expires value of a Contact, values higher than this 
		maximum will be automatically set to the maximum. Value 0 disables 
		the checking.
		</para>
		<para>
		<emphasis>
			Default value is 0.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>max_expires</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "max_expires", 120)
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>default_q</varname> (integer)</title>
		<para>
		The parameter represents default q value for new contacts. Because 
		ser doesn't support float parameter types, the value in the parameter 
		is divided by 100 and stored as float. For example, if you want 
		default_q to be 0.38, use value 38 here.
		</para>
		<para>
		<emphasis>
			Default value is 0.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>default_q</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "default_q", 100)
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>tcp_persistent_flag</varname> (integer)</title>
		<para>
		The parameter specifies the message flag to be used to control the 
		module behaviour regarding TCP connections. If the flag is set for a 
		REGISTER via TCP containing a TCP contact, the module, via the 
		<quote>save()</quote> functions will set the lifetime of the TCP
		connection to the contact expire value. By doing this, the TCP 
		connection will stay on as long as the contact is valid.
		</para>
		<para>
		<emphasis>
			Default value is -1 (disabled).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>tcp_persistent_flag</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "tcp_persistent_flag", 7)
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>realm_prefix</varname> (string)</title>
		<para>
		 Prefix to be automatically strip from realm. As an alternative to 
		 SRV records (not all SIP clients support SRV lookup), a subdomain of 
		 the master domain can be defined for SIP purposes (like 
		 sip.mydomain.net pointing to same IP address as the SRV record for 
		 mydomain.net). By ignoring the realm_prefix "sip.", at registration,
		 sip.mydomain.net will be equivalent to mydomain.net .
		</para>
		<para>
		<emphasis>
			Default value is NULL (none).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>realm_prefix</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "realm_prefix", "sip.")
...
</programlisting>
		</example>
	</section>


	<section>
		<title><varname>append_branches</varname> (integer)</title>
		<para>
		The parameter controls how lookup function processes multiple 
		contacts.  If there are multiple contacts for the given username in 
		usrloc and this parameter is set to 1, Request-URI will be 
		overwritten with the highest-q rated contact and the rest will be 
		appended to sip_msg structure and can be later used by tm for forking.
		If the parameter is set to 0, only Request-URI will be overwritten 
		with the highest-q rated contact and the rest will be left unprocessed.
		</para>
		<para>
		<emphasis>
			Default value is 1.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>append_branches</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "append_branches", 0)
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>aor_avp</varname> (str)</title>
		<para>
		If set, the module will try first to get the AOR from this AVP 
		instead of fetching it form the processed request.
		</para>
		<para>
		The AVP must contain a valid SIP URI. If no AVP is found, it will be
		tried to get the AOR from the message (standard behaviour).
		</para>
		<para>
		<emphasis>
			Default value is "NULL" (disabled).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>aor_avp</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "aor_avp", "$avp(i:3223)")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>case_sensitive</varname> (integer)</title>
		<para>
		If set to 1 then <acronym>AOR</acronym> comparison will be case 
		sensitive, if set to 0 then <acronym>AOR</acronym> comparison will 
		be case insensitive--This is recommended.
		</para>
		<para>
		<emphasis>
			Default value is 0.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>case_sensitive</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "case_sensitive", 1)
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>received_avp</varname> (str)</title>
		<para>
		Registrar will store the value of the AVP configured by this 
		parameter in the received column in the user location database. 
		It will leave the column empty if the AVP is empty. The AVP should 
		contain a SIP URI consisting of the source IP, port,
		and protocol of the REGISTER message being processed.
		</para>
		<note>
		<para>
			The value of this parameter should be the same as the value of 
			corresponding parameter of nathelper module.
		</para>
		</note>
		<para>
		<emphasis>
			Default value is "NULL" (disabled).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>received_avp</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "received_avp", "$avp(s:rcv)")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>received_param</varname> (string)</title>
		<para>
		The name of the parameter that will be appended to Contacts of 
		200 OK when the received URI was set by nathelper module.
		</para>
		<para>
		<emphasis>
			Default value is "received".
		</emphasis>
		</para>
		<example>
		<title>Set <varname>received_param</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "received_param", "rcv")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>max_contacts</varname> (integer)</title>
		<para>
		The parameter can be used to limit the number of contacts per 
		AOR (Address of Record) in the user location database. Value 0 
		disables the check.
		</para>
		<para>
		<emphasis>
			Default value is 0.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>max_contacts</varname> parameter</title>
		<programlisting format="linespecific">
...
# Allow no more than 10 contacts per AOR
modparam("registrar", "max_contacts", 10)
...
		</programlisting>
		</example>
	</section>

	<section>
		<title><varname>retry_after</varname> (integer)</title>
		<para>
		The registrar can generate 5xx reply to REGISTER in various 
		situations. It can, for example, happen when the 
		<varname>max_contacts</varname> parameter is set and the
		processing of REGISTER request would exceed the limit. In this case 
		the registrar would generate "503 Service Unavailable" response.
		</para>
		<para>
		If you want to add the Retry-After header field in 5xx replies, set 
		this parameter to a value grater than zero (0 means do not add the 
		header field). See section 20.33 of RFC3261 for more details.
		</para>
		<para>
		<emphasis>
			Default value is 0 (disabled).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>retry_after</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "retry_after", 30)
...
		</programlisting>
		</example>
	</section>

	<section>
		<title><varname>sock_flag</varname> (integer)</title>
		<para>
		Message flag to signal to register module to look into REGISTER 
		request for a header which contains a socket description (IP:port). 
		This socket info will be stored by register instead of the received 
		socket info.
		</para>
		<para>
		This make sens only in multiple replicated servers scenarios.
		</para>
		<para>
		<emphasis>
			Default value is -1 (no flag).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>sock_flag</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "sock_flag", 18)
...
		</programlisting>
		</example>
	</section>

	<section>
		<title><varname>sock_hdr_name</varname> (string)</title>
		<para>
		Header which contains a socket description (proto:IP:port) to overide
		the the received socket info. The header will be read only if the
		flag sock_flag is set.
		</para>
		<para>
		This make sens only in multiple replicated servers scenarios.
		</para>
		<para>
		<emphasis>
			Default value is NULL.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>sock_hdr_namer</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "sock_hdr_name", "Sock-Info")
...
		</programlisting>
		</example>
	</section>

	<section>
		<title><varname>method_filtering</varname> (integer)</title>
		<para>
		Tells if the contact filtering based on supported methods should be
		performed during lookup. It's enabled only if it has a non zero 
		value.
		</para>
		<para>
		<emphasis>
			Default value is 0 (disabled).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>method_filtering</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "method_filtering", 1)
...
		</programlisting>
		</example>
	</section>

	<section>
		<title><varname>use_path</varname> (integer)</title>
		<para>
		If set to 1, the Path header is handled according to the parameter 
		<quote>path_mode</quote>.
		</para>
		<para>
		<emphasis>
			Default value is 0 (disabled).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>use_path</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "use_path", 1)
...
		</programlisting>
		</example>
	</section>

	<section>
		<title><varname>path_mode</varname> (integer)</title>
		<para>
		The registrar module implements three different modes regarding the 
		response to a registration which includes one or more Path headers:
		</para>
		<itemizedlist>
		<listitem>
			<para>
			0 - The Path header is saved into usrloc, but is not included in 
			the reply.
			</para>
		</listitem>
		<listitem>
			<para>
			1 - The Path header is saved into usrloc, but is only included in 
			the reply if path support is indicated in the registration request 
			by the <quote>path</quote> option of the 
			<quote>Supported</quote> header.
			</para>
		</listitem>
		<listitem>
			<para>
			2 - The path header is only saved into usrloc, if path support is 
			indicated in the registration request by the <quote>path</quote> 
			option of the <quote>Supported</quote> header. If no path support 
			is indicated, the request is rejected with 
			<quote>420 - Bad Extension</quote> and the header 
			<quote>Unsupported: path</quote> is included in the reply along 
			with the received <quote>Path</quote> header. This mode is the 
			one recommended by RFC-3327.
			</para>
		</listitem>
		<para>
		<emphasis>
			Default value is 2.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>path_mode</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "path_mode", 0)
...
		</programlisting>
		</example>
	</section>

	<section>
		<title><varname>path_use_received</varname> (integer)</title>
		<para>
		If set to 1, the <quote>received</quote> parameter of the first Path 
		URI of a registration is set as received-uri and the NAT branch flag is
		set for this contact. This is useful if the registrar is placed
		behind a SIP loadbalancer, which passes the nat'ed UAC address as 
		<quote>received</quote> parameter
		in it's Path uri.
		</para>
		<para>
		<emphasis>
			Default value is 0 (disabled).
		</emphasis>
		</para>
		<example>
		<title>Set <varname>path_use_received</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("registrar", "path_use_received", 1)
...
		</programlisting>
		</example>
	</section>
	</section>

	<section>
	<title>Exported Functions</title>
	<section>
		<title>
		<function moreinfo="none">save(domain)</function>
		</title>
		<para>
		The function processes a REGISTER message. It can add, remove or 
		modify usrloc records depending on Contact and Expires HFs in the 
		REGISTER message. On success, 200 OK will be returned listing all 
		contacts that are currently in usrloc. On an error, error message 
		will be send with a short description in reason phrase.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para>
			<emphasis>domain</emphasis> - Logical domain within registrar. 
			If database is used then this must be name of the table which 
			stores the contacts.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function>save</function> usage</title>
		<programlisting format="linespecific">
...
save("location");
...
</programlisting>
		</example>
	</section>

	<section>
		<title>
		<function moreinfo="none">save(domain,flags)</function>
		</title>
		<para>
		Same as <function>save()</function> but it accepts a set of flags for
		controlling its behaviour.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para>
			<emphasis>domain</emphasis> - Logical domain within registrar. 
			If database is used then this must be name of the table which 
			stores the contacts.
			</para>
		</listitem>
		<listitem>
			<para>
			<emphasis>flags</emphasis> - the value may be a bitwise OR of 
			the following flags:
			</para>
			<itemizedlist>
				<listitem>
					<para><emphasis>0x01</emphasis> - save the contacts only
					in memory cache without no DB operation;
					</para>
				</listitem>
				<listitem>
					<para><emphasis>0x02</emphasis> - do not generate a SIP 
					reply to the current REGISTER request.
				</listitem>
			</itemizedlist>
			<para>The flags may be given in decimal or hexa format.</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function>save</function> usage</title>
		<programlisting format="linespecific">
...
save("location","0x01");
...
</programlisting>
		</example>
	</section>

	<section>
		<title>
		<function moreinfo="none">lookup(domain)</function>
		</title>
		<para>
		The functions extracts username from Request-URI and tries to find 
		all contacts for the username in usrloc. If there are no such 
		contacts, -1 will be returned.  If there are such contacts, 
		Request-URI will be overwritten with the contact that has
		the highest q value and optionally the rest will be appended to 
		the message (depending on append_branches parameter value).
		</para>
		<para>
		If the method_filtering option is enabled, the lookup function
		will return only the contacts that support the method of the
		processed request.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para>
			<emphasis>domain</emphasis> - Name of table that should be used 
			for the lookup.
			</para>
		</listitem>
		</itemizedlist>
		<para>Return codes:</para>
		<itemizedlist>
		<listitem>
			<para>
			<emphasis>1</emphasis> - contacts found and returned.
			</para>
			<para>
			<emphasis>-1</emphasis> - no contact found.
			</para>
			<para>
			<emphasis>-2</emphasis> - contacts found, but method not supported.
			</para>
			<para>
			<emphasis>-3</emphasis> - internal error during processing.
			</para>
		</listitem>
		</itemizedlist>

		<para>
		This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
		</para>
		<example>
		<title><function>lookup</function> usage</title>
		<programlisting format="linespecific">
...
lookup("location");
switch ($?) {
    case -1:
    case -3:
        sl_send_reply("404", "Not Found");
        exit;
    case -2:
        sl_send_reply("405", "Not Found");
        exit;
};
...
</programlisting>
		</example>
	</section>

	<section>
		<title>
		<function moreinfo="none">registered(domain)</function>
		</title>
		<para>
		The function returns true if the AOR in the Request-URI is 
		registered, false otherwise.  The function does not modify the 
		message being process, it neither rewrites the Request-URI if a 
		contact is found not append branches.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para>
			<emphasis>domain</emphasis> - Name of table that should be 
			used for the lookup.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
		</para>
		<example>
		<title><function>registered</function> usage</title>
		<programlisting format="linespecific">
...
if (registered("location")) {
	sl_send_reply("100", "Trying");
	...
};
...
</programlisting>
		</example>
	</section>

	<section>
		<title>
		<function moreinfo="none">add_sock_hdr(hdr_name)</function>
		</title>
		<para>
		Adds to the current REGISTER request a new header with 
		<quote>hdr_name</quote> which contains the description of the
		received socket (proto:ip:port)
		</para>
		<para>
		This make sens only in multiple replicated servers scenarios.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para>
			<emphasis>hdr_name</emphasis> - header name to be used.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function>add_sock_hdr</function> usage</title>
		<programlisting format="linespecific">
...
add_sock_hdr("Sock-Info");
...
</programlisting>
		</example>
	</section>
	</section>

<section>
	<title>Exported Statistics</title>
	<section>
		<title><varname>max_expires</varname></title>
		<para>
		Value of max_expires parameter.
		</para>
	</section>
	<section>
		<title><varname>max_contacts</varname></title>
		<para>
		The value of max_contacts parameter.
		</para>
	</section>
	<section>
		<title><varname>defaults_expires</varname></title>
		<para>
		The value of default_expires parameter.
		</para>
	</section>
	<section>
		<title><varname>accepted_regs</varname></title>
		<para>
		Number of accepted registrations.
		</para>
	</section>
	<section>
		<title><varname>rejected_regs</varname></title>
		<para>
		Number of rejected registrations.
		</para>
	</section>

</section>

</chapter>

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