kamailio/modules/siputils/doc/siputils_admin.xml

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

<chapter>
	
	<title>&adminguide;</title>
	
	<section>
	<title>Overview</title>
	<para>
	This module implement various functions and checks related to SIP message
	handling and URI handling.
	</para>
	<para>
	It offers some functions related to handle ringing. In a parallel forking
	scenario you get several 183s with SDP. You don't want that your customers
	hear more than one ringtone or answer machine in parallel on the phone.
	So its necessary to drop the 183 in this cases and send a 180 instead.
	</para>
	<para>
	This module also provides a function to answer OPTIONS requests which 
	are directed to the server itself. This means an OPTIONS request 
	which has the address of the server in the request URI, and no 
	username in the URI. The request will be answered with a 200 OK 
	with the capabilities of the server.
	</para>
	<para>
	To answer OPTIONS request directed to your server is the easiest
	way for is-alive-tests on the SIP (application) layer from remote 
	(similar to ICMP echo requests, also known as <quote>ping</quote>, 
	on the network layer).
	</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>sl</emphasis> -- Stateless replies.
			</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>ring_timeout</varname> (int)</title>
			<para>
			Timeout value in seconds, define how long the call-id is stored in the internal list kept for replacing 183 messages  with 180.
			A reasonable value is <quote>30</quote>.
			</para>
			<para>
			<emphasis>
				Default value is <quote>0</quote>. This means functionality is disabled.
			</emphasis>
			</para>
			<example>
			<title>Set <varname>ring_timeout</varname> parameter</title>
				<programlisting format="linespecific">
...
modparam("siputils", "ring_timeout", 30)
...
				</programlisting>
			</example>
		</section>
			<section>
		<title><varname>options_accept</varname> (string)</title>
		<para>
			This parameter is the content of the Accept header field.
			Note: it is not clearly written in RFC3261 if a proxy should
			accept any content (the default <quote>*/*</quote>) because 
			it does not care about content. Or if it does not accept 
			any content, which is <quote></quote>.
		</para>
		<para>
		<emphasis>
			Default value is <quote>*/*</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>options_accept</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("siputils", "options_accept", "application/*")
...
</programlisting>
		</example>
	</section>
	<section>
		<title><varname>options_accept_encoding</varname> (string)</title>
		<para>
			This parameter is the content of the Accept-Encoding header field.
			Please do not change the default value because &kamailio; 
			does not support any encodings yet.
		</para>
		<para>
		<emphasis>
			Default value is <quote></quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>options_accept_encoding</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("siputils", "options_accept_encoding", "gzip")
...
</programlisting>
		</example>
	</section>

		<section>
		<title><varname>contact_flds_separator</varname> (string)</title>
		<para>
		First char of this parameter is used as separator for encoding/decoding 
		Contact header.
		</para>
		<warning>
		<para>
			First char of this field must be set to a value which is not used 
			inside username,password or other fields of contact. Otherwise it 
			is possible for the decoding step to fail/produce wrong results.
		</para>
		</warning>
		<para>
		<emphasis>
			Default value is <quote>*</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>contact_flds_separator</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("siputils", "contact_flds_separator", "-")
...
</programlisting>
		</example>
		<para>
		then an encoded uri might look 
		sip:user-password-ip-port-protocol@PublicIP
		</para>
	</section>


	<section>
		<title><varname>options_accept_language</varname> (string)</title>
		<para>
			This parameter is the content of the Accept-Language header field.
			You can set any language code which you prefer for error 
			descriptions from other devices, but presumably there are not
			many devices around which support other languages than the 
			default English.
		</para>
		<para>
		<emphasis>
			Default value is <quote>en</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>options_accept_language</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("siputils", "options_accept_language", "de")
...
</programlisting>
		</example>
	</section>
	<section>
		<title><varname>options_support</varname> (string)</title>
		<para>
			This parameter is the content of the Support header field,
			indicating SIP extensions.
			Please do not change the default value, because &kamailio; currently 
			does not support any of the SIP extensions registered at the IANA.
		</para>
		<para>
		<emphasis>
			Default value is <quote></quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>options_support</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("siputils", "options_support", "100rel")
...
</programlisting>
		</example>
	</section>
	<section>
		<title><varname>rpid_prefix</varname> (string)</title>
		<para>
		Prefix to be added to Remote-Party-ID header field just before 
		the URI returned from either radius or database.
		</para>
		<para>
		Default value is <quote></quote>.
		</para>
		<example>
		<title>rpid_prefix parameter example</title>
		<programlisting format="linespecific">
modparam("auth", "rpid_prefix", "Whatever &lt;")
</programlisting>
		</example>
	</section>
	<section>
		<title><varname>rpid_suffix</varname> (string)</title>
		<para>
		Suffix to be added to Remote-Party-ID header field after the URI 
		returned from either radius or database.
		</para>
		<para>
		Default value is 
			<quote>;party=calling;id-type=subscriber;screen=yes</quote>.
		</para>
		<example>
		<title>rpid_suffix parameter example</title>
		<programlisting format="linespecific">
modparam("auth", "rpid_suffix", "@1.2.3.4>")
</programlisting>
		</example>
	</section>
	<section>
		<title><varname>rpid_avp</varname> (string)</title>
		<para>
			Full AVP specification for the AVP which 
			stores the RPID value. It used to transport the RPID value from
			authentication backend modules (auth_db or auth_radius) or from
			script to the auth function append_rpid_hf and is_rpid_user_e164.
		</para>
		<para>
			If defined to NULL string, all RPID functions will fail at 
			runtime.
		</para>
		<para>
		Default value is <quote>$avp(s:rpid)</quote>.
		</para>
		<example>
		<title>rpid_avp parameter example</title>
		<programlisting format="linespecific">
modparam("auth", "rpid_avp", "$avp(myrpid)")
		</programlisting>
		</example>
	</section>
	</section>

	<section>
	<title>Functions</title>
		<section id="siputils.f.ring_insert_callid">
			<title>
				<function moreinfo="none">ring_insert_callid()</function>
			</title>
			<para>
			Inserting the call-id in the internal list, which is checked when
			further replies arrive. Any 183 reply that is received during the
			timeout value will be converted to a 180 message. Please note that you
			need to set a positive timeout value in order to use this function.
			</para>
			<para>
			The function returns TRUE on success, and FALSE during processing failures.
			</para>
			<para>
			This function can be used from REQUEST_ROUTE and FAILURE_ROUTE.
			</para>
			<example>
				<title><function>ring_insert_callid()</function> usage</title>
				<programlisting format="linespecific">
...
ring_insert_callid();
...
				</programlisting>
			</example>
	</section>
	<section id="siputils.f.options_reply">
		<title>
		<function moreinfo="none">options_reply()</function>
		</title>
		<para>
			This function checks if the request method is OPTIONS and
			if the request URI does not contain an username. If both
			is true the request will be answered stateless with 
			<quote>200 OK</quote> and the capabilities from the modules
			parameters.
		</para>
		<para>
			It sends <quote>500 Server Internal Error</quote> for some errors
			and returns false if it is called for a wrong request.
		</para>
		<para>
			The check for the request method and the missing username is
			optional because it is also done by the function itself. But
			you should not call this function outside the myself check
			because in this case the function could answer OPTIONS requests
			which are sent to you as outbound proxy but with an other
			destination then your proxy (this check is currently missing
			in the function).
		</para>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function>options_reply</function> usage</title>
		<programlisting format="linespecific">
...
if (uri==myself) {
	if ((method==OPTIONS) &amp;&amp; (! uri=~"sip:.*[@]+.*")) {
		options_reply();
	}
}
...
</programlisting>
		</example>
	</section>

	<section id="siputils.f.is_user">
		<title>
		<function moreinfo="none">is_user(username)</function>
		</title>
		<para>
		Check if the username in credentials matches the given username.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para><emphasis>username</emphasis> - Username string.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function>is_user</function> usage</title>
		<programlisting format="linespecific">
...
if (is_user("john")) {
	...
};
...
</programlisting>
		</example>
	</section>
	<section id="siputils.f.has_totag()">
		<title>
		<function moreinfo="none">has_totag()</function>
		</title>
		<para>
		Check if To header field uri contains tag parameter.
		</para>
		<para>
		This function can be used from ANY_ROUTE.
		</para>
		<example>
		<title><function>has_totag</function> usage</title>
		<programlisting format="linespecific">
...
if (has_totag()) {
	...
};
...
</programlisting>
		</example>
	</section>
	<section>
		<title id="siputils.f.uri_param">
		<function moreinfo="none">uri_param(param)</function>
		</title>
		<para>
		Find if Request URI has a given parameter with no value
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para><emphasis>param</emphasis> - parameter name to look for.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function>uri_param</function> usage</title>
		<programlisting format="linespecific">
...
if (uri_param("param1")) {
	...
};
...
</programlisting>
		</example>
	</section>
	<section id="siputils.f.uri_param_value">
		<title>
		<function moreinfo="none">uri_param(param,value)</function>
		</title>
		<para>
		Find if Request URI has a given parameter with matching value
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para><emphasis>param</emphasis> - parameter name to look for.
			</para>
		</listitem>
		<listitem>
			<para><emphasis>value</emphasis> - parameter value to match.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function>uri_param</function> usage</title>
		<programlisting format="linespecific">
...
if (uri_param("param1","value1")) {
	...
};
...
</programlisting>
		</example>
	</section>
	<section id="siputils.f.add_uri_param">
		<title>
		<function moreinfo="none">add_uri_param(param)</function>
		</title>
		<para>
		Add to RURI a parameter (name=value);
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para><emphasis>param</emphasis> - parameter to be appended in
			<quote>name=value</quote> format.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function>add_uri_param</function> usage</title>
		<programlisting format="linespecific">
...
add_uri_param("nat=yes");
...
</programlisting>
		</example>
	</section>
	<section id="siputils.f.get_uri_param">
		<title>
		<function moreinfo="none">get_uri_param(name, var)</function>
		</title>
		<para>
		Get the value of RURI parameter.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para><emphasis>name</emphasis> - the name of R-URI parameter</para>
		</listitem>
		<listitem>
			<para><emphasis>var</emphasis> - the variable where to store the
			value of the parameter</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function>add_uri_param</function> usage</title>
		<programlisting format="linespecific">
...
get_uri_param("nat", "$var(nat)");
...
</programlisting>
		</example>
	</section>
	<section id="siputils.f.tel2sip">
		<title>
		<function moreinfo="none">tel2sip(uri, hostpart, result)</function>
		</title>
		<para>
		Converts URI in first param (pseudo variable or string) to
		SIP URI, if it is a tel URI.  If conversion was done,
		writes resulting SIP URI to third param (pseudo variable).
		Returns 1 if conversion succeeded or if no conversion
		was needed.
		</para>
		<para>
		The conversion follows the rules in RFC 3261 section 19.1.6:
		<itemizedlist>
                <listitem>
                        <para>Visual separators ( "-", ".", "(", ")" ) are removed from tel URI number before converting it to SIP URI userinfo.</para>
		</listitem>
		<listitem>
			<para>tel URI parameters are downcased before appending them to SIP URI userinfo</para>
                </listitem>
                </itemizedlist>
		</para>
		<para>
		The SIP URI hostpart is taken from second param
		(pseudo variable or string).
		</para>
		<para>
		This function can be used from REQUEST_ROUTE, FAILURE_ROUTE,
		BRANCH_ROUTE, or ONREPLY_ROUTE.
		</para>
		<example>
		<title><function>tel2sip</function> usage</title>
		<programlisting format="linespecific">
...
# $ru: tel:+(34)-999-888-777
# $fu: sip:[email protected]
tel2sip("$ru", $fd", "$ru");
# $ru:  sip:[email protected];user=phone

# $ru: tel:+12-(34)-56-78;Ext=200;ISUB=+123-456
# $fu: sip:[email protected]
tel2sip("$ru", $fd", "$ru");
# $ru:  sip:+12345678;ext=200;[email protected];user=phone
...
</programlisting>
		</example>
	</section>

	<section id="siputils.f.is_e164">
		<title>
		<function moreinfo="none">is_e164(pseudo-variable)</function>
		</title>
		<para>
		Checks if string value of pseudo variable argument is an
		E164 number.
		</para>
		<para>
		This function can be used from REQUEST_ROUTE,
		FAILURE_ROUTE, and LOCAL_ROUTE.
		</para>
		<example>
		<title><function>is_e164</function> usage</title>
		<programlisting format="linespecific">
...
if (is_164("$fU")) {  # Check From header URI user part
   ...
}
if (is_e164("$avp(i:705)") {
   # Check stgring value stored in avp i:705
   ...
};
...
</programlisting>
		</example>
	</section>

	<section id="siputils.f.is_uri_user_e164">
		<title>
		<function moreinfo="none">is_uri_user_e164(pseudo-variable)</function>
		</title>
		<para>
		Checks if userpart of URI stored in pseudo variable is
		E164 number.
		</para>
		<para>
		This function can be used from ANY_ROUTE.
		</para>
		<example>
		<title><function>is_uri_user_e164</function> usage</title>
		<programlisting format="linespecific">
...
if (is_uri_user_e164("$fu")) {  # Check From header URI user part
   ...
}
if (is_uri_user_e164("$avp(i:705)") {
   # Check user part of URI stored in avp i:705
   ...
};
...
</programlisting>
		</example>
	</section>

	<section id="siputils.f.encode_contact">
		<title>
		<function moreinfo="none">encode_contact(encoding_prefix,hostpart)</function>
		</title>
		<para>
		This function will encode uri-s inside Contact header in the following 
		manner
		sip:username:password@ip:port;transport=protocol goes
		sip:encoding_prefix*username*ip*port*protocol@hostpart.
		</para>
		<para>
		* is the default separator and can be changed by setting the contact_flds_separator 
		module parameter.
		</para>
		<para>
		Note: This function discards all of the URI parameters. Thus, none of the parameters
		(except the transport parameter which is encoded into the userpart) can be restored.
		</para>
		<para>
		The function returns negative on error, 1 on success.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para><emphasis>encoding_prefix</emphasis> - Something to allow us 
			to determine that a contact is encoded.
			</para>
		</listitem>
		<listitem>
			<para><emphasis>hostpart</emphasis> - An IP address or a hostname.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE.
		</para>
		<example>
		<title><function>encode_contact</function> usage</title>
		<programlisting format="linespecific">
...
if (src_ip == 10.0.0.0/8) encode_contact("natted_client","1.2.3.4"); 
...
</programlisting>
		</example>
	</section>

	<section id="siputils.f.decode_contact">
		<title>
		<function moreinfo="none">decode_contact()</function>
		</title>
		<para>
		This function will decode the request URI. If the RURI is in the format
		sip:encoding_prefix*username*ip*port*protocol@hostpart it will be decoded to
		sip:username:password@ip:port;transport=protocol It uses the default 
		set parameter for contact encoding separator.
		</para>
		<para>
		The function returns negative on error, 1 on success.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function>decode_contact</function> usage</title>
		<programlisting format="linespecific">
...
if (uri =~ "^sip:natted_client") { decode_contact(); }
...
</programlisting>
		</example>
	</section>

	<section id="siputils.f.decode_contact_header">
		<title>
		<function moreinfo="none">decode_contact_header()</function>
		</title>
		<para>
		This function will decode &uri;s inside Contact header. If the URI in the format 
		sip:encoding_prefix*username*ip*port*protocol@hostpart it will be decoded to
		sip:username:password@ip:port;transport=protocol. It uses the 
		default set parameter for contact encoding separator.
		</para>
		<para>
		The function returns negative on error, 1 on success.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<para>
		This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE.
		</para>
		<example>
		<title><function>decode_contact_header</function> usage</title>
		<programlisting format="linespecific">
...
reply_route[2] {
	...
	decode_contact_header();
	...
}
...
</programlisting>
		</example>
	</section>
	<section id="siputils.f.cmp_uri">
		<title>
		<function moreinfo="none">cmp_uri(str1, str2)</function>
		</title>
		<para>
		The function returns <emphasis>true</emphasis> if 
		the two parameters matches as SIP URI.
		</para>
   		<para>
		This function can be used from ANY_ROUTE.
		</para>
		<example>
		<title><function>cmp_uri</function> usage</title>
		<programlisting format="linespecific">
...
if(cmp_uri("$ru", "sip:[email protected]"))
{
    # do interesting stuff here
}
...
</programlisting>
		</example>
	</section>

	<section id="siputils.f.cmp_aor">
		<title>
		<function moreinfo="none">cmp_aor(str1, str2)</function>
		</title>
		<para>
		The function returns <emphasis>true</emphasis> if 
		the two parameters matches as AoR. The parameters have to be SIP
		URIs.
		</para>
   		<para>
		This function can be used from ANY_ROUTE.
		</para>
		<example>
		<title><function>cmp_aor</function> usage</title>
		<programlisting format="linespecific">
...
if(cmp_aor("[email protected]", "sip:kamailio@$fd"))
{
    # do interesting stuff here
}
...
</programlisting>
		</example>
	</section>
	<section  id="siputils.f.append_rpid_hf">
		<title>
			<function moreinfo="none">append_rpid_hf()</function></title>
		<para>
		Appends to the message a Remote-Party-ID header that contains header
		'Remote-Party-ID: ' followed by the saved value of the SIP URI 
		received from the database or radius server followed by the value of 
		module parameter radius_rpid_suffix.  The function does nothing if 
		no saved SIP URI exists.
		</para>
		<para>
		This function can be used from REQUEST_ROUTE, FAILURE_ROUTE,
		BRANCH_ROUTE.
		</para>
		<example>
		<title>append_rpid_hf usage</title>
		<programlisting format="linespecific">
...
append_rpid_hf();  # Append Remote-Party-ID header field
...
</programlisting>
		</example>
	</section>
	<section id="siputils.f.append_rpid_hf_params">
		<title>
			<function moreinfo="none">append_rpid_hf(prefix, suffix)</function>
		</title>
		<para>
		This function is the same as 
		<xref linkend="siputils.f.append_rpid_hf"/>. The only difference is
		that it accepts two parameters--prefix and suffix to be added to 
		Remote-Party-ID header field. This function ignores rpid_prefix and 
		rpid_suffix parameters, instead of that allows to set them in every 
		call.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para><emphasis>prefix</emphasis> - Prefix of the 
			Remote-Party-ID URI. The string will be added at the begining of 
			body of the header field, just before the URI.
			</para>
		</listitem>
		<listitem>
			<para><emphasis>suffix</emphasis> - Suffix of the Remote-Party-ID 
			header field. The string will be appended at the end of the 
			header field. It can be used to set various URI parameters, 
			for example.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE, FAILURE_ROUTE,
		BRANCH_ROUTE.
		</para>
		<example>
		<title>append_rpid_hf(prefix, suffix) usage</title>
		<programlisting format="linespecific">
...
# Append Remote-Party-ID header field
append_rpid_hf("", ";party=calling;id-type=subscriber;screen=yes");
...
</programlisting>
		</example>
	</section>
	<section>
		<title id="siputils.f.is_rpid_user_e164">
			<function moreinfo="none">is_rpid_user_e164()</function>
		</title>
		<para>
		The function checks if the SIP URI received from the database or 
		radius server and will potentially be used in Remote-Party-ID header 
		field contains an E164 number (+followed by up to 15 decimal digits) 
		in its user part.  Check fails, if no such SIP URI exists 
		(i.e. radius server or database didn't provide this information).
		</para>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title>is_rpid_user_e164 usage</title>
		<programlisting format="linespecific">
...
if (is_rpid_user_e164()) {
    # do something here
};
...
</programlisting>
		</example>
	</section>
	<section id="siputils.f.set_uri_user">
		<title>
			<function moreinfo="none">set_uri_user(uri, user)</function>
		</title>
		<para>
		Sets userpart of SIP URI stored in writable pseudo variable
		'uri' to value of pseudo variable 'user'.
		</para>
		<para>
		This function can be used from ANY_ROUTE.
		</para>
		<example>
		<title>set_uri_user usage</title>
		<programlisting format="linespecific">
...
$var(uri) = "sip:user@host";
$var(user) = "new_user";
set_uri_user("$var(uri)", "$var(user)");
...
</programlisting>
		</example>
	</section>
	<section id="siputils.f.set_uri_host">
		<title>
			<function moreinfo="none">set_uri_host(uri, host)</function>
		</title>
		<para>
		Sets hostpart of SIP URI stored in writable pseudo variable
		'uri' to value of pseudo variable 'host'.
		</para>
		<para>
		This function can be used from ANY_ROUTE.
		</para>
		<example>
		<title>set_uri_host usage</title>
		<programlisting format="linespecific">
...
$var(uri) = "sip:user@host";
$var(host) = "new_host";
set_uri_host("$var(uri)", "$var(host)");
...
</programlisting>
		</example>
	</section>
	<section id="siputils.f.is_request">
		<title>
		<function moreinfo="none">is_request()</function>
		</title>
		<para>
		Return true if the SIP message is a request.
		</para>
		<para>
		This function can be used from ANY_ROUTE.
		</para>
		<example>
		<title><function>is_request</function> usage</title>
		<programlisting format="linespecific">
...
if (is_request()) {
	...
}
...
</programlisting>
		</example>
	</section>
	<section id="siputils.f.is_reply">
		<title>
		<function moreinfo="none">is_reply()</function>
		</title>
		<para>
		Return true if the SIP message is a reply.
		</para>
		<para>
		This function can be used from ANY_ROUTE.
		</para>
		<example>
		<title><function>is_reply</function> usage</title>
		<programlisting format="linespecific">
...
if (is_reply()) {
	...
}
...
</programlisting>
		</example>
	</section>
	<section id="siputils.f.is_gruu">
		<title>
			<function moreinfo="none">is_gruu([uri])</function>
		</title>
		<para>
			The function returns true if the uri is GRUU ('gr' parameter
			is present): 1 - pub-gruu; 2 - temp-gruu.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para><emphasis>uri</emphasis> - the SIP URI to check for
				GRUU parameter. It is optional, when missing, the value
				of R-URI is used.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from ANY_ROUTE.
		</para>
		<example>
		<title>is_gruu() usage</title>
		<programlisting format="linespecific">
...
if(is_gruu()) { ... }
...
</programlisting>
		</example>
	</section>
	<section id="siputils.f.is_supported">
		<title>
			<function moreinfo="none">is_supported(option)</function>
		</title>
		<para>
			Function returns true if given option is listed
			in Supported header(s) (if any) of the request.
			Currently the following options are known: path,
			100rel, timer, eventlist, gruu, and outbound.
			
		</para>
		<para>
		This function can be used from ANY_ROUTE.
		</para>
		<example>
		<title>is_supported() usage</title>
		<programlisting format="linespecific">
...
if (is_supported("outbound")) { ... }
...
</programlisting>
		</example>
	</section>
	<section id="siputils.f.is_first_hop">
		<title>
			<function moreinfo="none">is_first_hop()</function>
		</title>
		<para>
		The function returns true if the proxy is first hop after the
		original sender. For incoming SIP requests, it means there is only
		one Via header. For incoming SIP replies, it means that top
		Record-Route URI is 'myself' and source address is not matching it
		(to avoid detecting in case of local loops). Note that it does not
		detect spirals, which can have the condition for replies true also
		in the case of additional SIP reply receival.
		</para>
		<para>
		This function can be used from ANY_ROUTE.
		</para>
		<example>
		<title>is_first_hop() usage</title>
		<programlisting format="linespecific">
...
if(is_first_hop()) { ... }
...
</programlisting>
		</example>
	</section>
	</section>

</chapter>