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<section id="tm.functions" xmlns:xi="http://www.w3.org/2001/XInclude">
    <sectioninfo>
	<revhistory>
	    <revision>
		<revnumber>$Revision$</revnumber>
		<date>$Date$</date>
	    </revision>
	</revhistory>
    </sectioninfo>

    <title>Functions</title>

    <section id="t_relay_to_udp">
	<title>
	    <function>t_relay_to_udp(ip, port)</function>,
	    <function>t_relay_to_udp()</function>,
	    <function>t_relay_to_tcp(ip, port)</function>
	    <function>t_relay_to_tcp()</function>
	    <function>t_relay_to_tls(ip, port)</function>
	    <function>t_relay_to_tls()</function>
	</title>
	<para>
	    Relay a message statefully using a fixed protocol either to the 
		 specified fixed destination or to a destination derived from the 
		 message uri (if the host address and port are not specified).
		 These along with
	    <function>t_relay</function> are the functions most users want to
	    use--all other are mostly for programming. Programmers interested
	    in writing <acronym>TM</acronym> logic should review how t_relay is
	    implemented in tm.c and how <acronym>TM</acronym> callbacks work.
	</para>
	<para>Meaning of the parameters is as follows:</para>
	<itemizedlist>
	    <listitem>
		<para><emphasis>ip</emphasis> - IP address where the message should be sent.
		</para>
	    </listitem>
	    <listitem>
		<para><emphasis>port</emphasis> - Port number.
		</para>
	    </listitem>
	</itemizedlist>
	<para>If no parameters are specified the message is sent to a destination
	 derived from the message uri (using sip sepcific DNS lookups), but with 
	 the protocol corresponding to the function name.</para>
	<example>
	    <title><function>t_relay_to_udp</function> usage</title>
	    <programlisting>
...
if (src_ip==10.0.0.0/8)
	t_relay_to_udp("1.2.3.4", "5060"); # sent to 1.2.3.4:5060 over udp
else
	t_relay_to_tcp(); # relay to msg. uri, but over tcp
...
	    </programlisting>
	</example>
    </section>

    <section id="t_relay">
	<title>
	    <function>t_relay()</function>
	    <function>t_relay(host, port)</function>
	</title>
	<para>
	    Relay a message statefully either to the destination indicated in the
		current URI (if called without any parameters) or to the specified 
		host and port. In the later case (host and port specified) the protocol
		 used is the same protocol on which the message was received.
	</para>
	<para>
		<function>t_relay()</function> is the statefull version for 
		<function>forward(uri:host, uri:port)</function>
		while <function>t_relay(host, port)</function> is similar to 
		<function>forward(host, port)</function>.
	</para>
	<para>
		In the forward to uri case (<function>t_relay()</function>), if the
	    original URI was rewritten (by UsrLoc, RR, strip/prefix, etc.) the new
		URI will be taken). The destination (including the protocol) is 
		determined from the uri, using SIP specific DNS resolving if needed
		(NAPTR, SRV a.s.o depending also on the dns options).
	</para>
	<para>
		Returns a negative value on failure--you may still want to send a
	    negative reply upstream statelessly not to leave upstream UAC in lurch.
	</para>
	<example>
	    <title><function>t_relay</function> usage</title>
	    <programlisting>
...
if (!t_relay()) 
{ 
    sl_reply_error(); 
    break; 
};
...
	    </programlisting>
	</example>
    </section>
    
    <section id="t_on_failure">
	<title>
	    <function>t_on_failure(failure_route)</function>
	</title>
	<para>
	    Sets failure routing block, to which control is passed after a
	    transaction completed with a negative result but before sending a
	    final reply. In the referred block, you can either start a new
	    branch (good for services such as forward_on_no_reply) or send a
	    final reply on your own (good for example for message silo, which
	    received a negative reply from upstream and wants to tell upstream
	    "202 I will take care of it"). Note that the set of
	    commands which are usable within failure_routes is strictly limited to
	    rewriting URI, initiating new branches, logging, and sending
	    stateful replies (<function>t_reply</function>). Any other commands
	    may result in unpredictable behavior and possible server
	    failure. Note that whenever failure_route is entered, uri is reset to
	    value which it had on relaying. If it temporarily changed during a
	    reply_route processing, subsequent reply_route will ignore the
	    changed value and use again the original one.
	</para>
	<para>Meaning of the parameters is as follows:</para>
	<itemizedlist>
	    <listitem>
		<para><emphasis>failure_route</emphasis> - Failure route block to be called.
		</para>
	    </listitem>
	</itemizedlist>
	<example>
	    <title><function>t_on_failure</function> usage</title>
	    <programlisting>
...
route { 
    t_on_failure("1"); 
    t_relay(); 
} 

failure_route[1] {
    revert_uri(); 
    setuser("voicemail"); 
    append_branch(); 
}
...
	    </programlisting>
	</example>
	<para>
	    See <filename>test/onr.cfg</filename> for a more complex example of
	    combination of serial with parallel forking.
	</para>
    </section>
 
	 <section id="t_on_reply">
	<title>
	    <function>t_on_reply(onreply_route)</function>
	</title>
	<para>
	    Sets the reply routing block, to which control is passed when a
	    reply for the current transaction is received.
	    Note that the set of commands which are usable within onreply_routes is
	     limited.
	</para>
	<para>Meaning of the parameters is as follows:</para>
	<itemizedlist>
	    <listitem>
		<para><emphasis>onreply_route</emphasis> - Onreply route block to be
			called.
		</para>
	    </listitem>
	</itemizedlist>
	<example>
	    <title><function>t_on_reply</function> usage</title>
	    <programlisting>
...
loadmodule "/usr/local/lib/ser/modules/nathelper.so"
...
route { 
	/* if natted */
	t_on_reply("1"); 
	t_relay(); 
} 

onreply_route[1] {
	if (status=~ "(183)|2[0-9][0-9]"){
		force_rtp_proxy();
		search_append('^(Contact|m)[ \t]*:.*sip:[^>[:cntrl:]]*', ';nat=yes');
	}
	if (nat_uac_test("1")){
		fix_nated_contact();
	}
}
	    </programlisting>
	</example>
	</section>

	<section id="t_on_branch">
	<title>
	    <function>t_on_branch(branch_route)</function>
	</title>
	<para>
	    Sets the branch routing block, to which control is passed after
	    forking (when a new branch is created). For now branch routes
	    are intended only for last minute changes of the SIP messages
	    (like adding new headers).
	    Note that the set of commands which are usable within branch_routes is
	    very limited. It is not possible to drop a message or generate a reply.
	</para>
	<para>Meaning of the parameters is as follows:</para>
	<itemizedlist>
	    <listitem>
		<para><emphasis>branch_route</emphasis> - branch route block to be
			called.
		</para>
	    </listitem>
	</itemizedlist>
	<example>
	    <title><function>t_on_branch</function> usage</title>
	    <programlisting>
...
route { 
	t_on_branch("1"); 
	t_relay(); 
} 

branch_route[1] {
	if (uri=~"sip:[0-9]+"){
		append_hf("P-Warn: numeric uri\r\n");
	}
}
	    </programlisting>
	</example>
	</section>

    <section id="append_branch">
	<title>
	    <function>append_branch()</function>
	</title>
	<para>
	    Similarly to <function>t_fork_to</function>, it extends destination
	    set by a new entry. The difference is that current URI is taken
	    as new entry.
	</para>
	<example>
	    <title><function>append_branch</function> usage</title>
	    <programlisting>
...
set_user("john"); 
t_fork(); 
set_user("alice");
t_fork(); 
t_relay();
...
	    </programlisting>
	</example>
    </section>

    <section id="t_newtran">
	<title>
	    <function>t_newtran()</function>
	</title>
	<para>
	    Creates a new transaction, returns a negative value on error. This
	    is the only way a script can add a new transaction in an atomic
	    way. Typically, it is used to deploy a UAS.
	</para>
	<example>
	    <title><function>t_newtran</function> usage</title>
	    <programlisting>
...
if (t_newtran()) { 
    log("UAS logic"); 
    t_reply("999","hello"); 
} else sl_reply_error();
...
	    </programlisting>
	</example>
	<para>
	    See test/uas.cfg for more examples.
	</para>
    </section>

    <section id="t_reply">
	<title>
	    <function>t_reply(code, reason_phrase)</function>
	</title>
	<para>
	    Sends a stateful reply after a transaction has been
	    established. See <function>t_newtran</function> for usage.
	</para>
	<para>Meaning of the parameters is as follows:</para>
	<itemizedlist>
	    <listitem>
		<para><emphasis>code</emphasis> - Reply code number.
		</para>
	    </listitem>
	    <listitem>
		<para><emphasis>reason_phrase</emphasis> - Reason string.
		</para>
	    </listitem>
	</itemizedlist>
	<example>
	    <title><function>t_reply</function> usage</title>
	    <programlisting>
...
t_reply("404", "Not found");
...
	    </programlisting>
	</example>
    </section>

    <section id="t_lookup_request">
	<title>
	    <function>t_lookup_request()</function>
	</title>
	<para>
	    Checks if a transaction exists. Returns a positive value if so,
	    negative otherwise.  Most likely you will not want to use it, as a
	    typical application of a looku-up is to introduce a new transaction
	    if none was found. However this is safely (atomically) done using
	    <function>t_newtran</function>.
	</para>
	<example>
	    <title><function>t_lookup_request</function> usage</title>
	    <programlisting>
...
if (t_lookup_request()) {
    ...
};
...
	    </programlisting>
	</example>
    </section>

    <section id="t_retransmit_reply">
	<title>
	    <function>t_retransmit_reply()</function>
	</title>
	<para>
	    Retransmits a reply sent previously by UAS transaction.
	</para>
	<example>
	    <title><function>t_retransmit_reply</function> usage</title>
	    <programlisting>
...
t_retransmit_reply();
...
	    </programlisting>
	</example>
    </section>

    <section id="t_release">
	<title>
	    <function>t_release()</function>
	</title>
	<para>
	    Remove transaction from memory (it will be first put on a wait
	    timer to absorb delayed messages).
	</para>
	<example>
	    <title><function>t_release</function> usage</title>
	    <programlisting>
...
t_release();
...
	    </programlisting>
	</example>
    </section>

    <section id="t_forward_nonack">
	<title>
	    <function>t_forward_nonack(ip, port)</function>
	</title>
	<para>
	    mainly for internal usage--forward a non-ACK request statefully.
	</para>
	<para>Meaning of the parameters is as follows:</para>
	<itemizedlist>
	    <listitem>
		<para><emphasis>ip</emphasis> - IP address where the message should be sent.
		</para>
	    </listitem>
	    <listitem>
		<para><emphasis>port</emphasis> - Port number.
		</para>
	    </listitem>
	</itemizedlist>
	<example>
	    <title><function>t_forward_nonack</function> usage</title>
	    <programlisting>
...
t_forward_nonack("1.2.3.4", "5060");
...
	    </programlisting>
	</example>
    </section>

	<section id="t_set_fr">
	<title>
	    <function>t_set_fr(fr_inv_timeout [, fr_timeout])</function>
	</title>
	<para>
		Sets the fr_inv_timeout and optionally fr_timeout for the current
		transaction or for transactions created during the same script 
		invocation, after calling this function.
		If the transaction is already created (e.g called after
		 <function>t_relay()</function> or in an onreply_route) all the
		 branches will have their final response timeout updated on-the-fly.
		If one of the parameters is 0, it's value won't be changed.
	</para>
	<para>Meaning of the parameters is as follows:</para>
	<itemizedlist>
	    <listitem>
		<para><emphasis>fr_inv_timeout</emphasis> - new final response timeout
			(in milliseconds) for INVITEs. See also 
			<varname>fr_inv_timer</varname>.
		</para>
		<para><emphasis>fr_timeout</emphasis> - new final response timeout
		 	(in milliseconds) for non-INVITE transaction, or INVITEs which 
			haven't received yet a provisional response. See also
			<varname>fr_timer</varname>.
		</para>
	    </listitem>
	</itemizedlist>
	<example>
	    <title><function>t_set_fr</function> usage</title>
	    <programlisting>
...
route { 
	t_set_fr(10000); # set only fr invite timeout to 10s
	t_on_branch("1");
	t_relay(); 
} 

branch_route[1] {
	# if we are calling the pstn, extend the invite timeout to 50s
	# for all the branches, and set the no-reply-received timeout to 2s
	if (uri=~"sip:[0-9]+"){
		t_set_fr(50000, 2000); 
	}
}
	    </programlisting>
	</example>
	</section>

	<section id="t_set_retr">
	<title>
	    <function>t_set_retr(retr_t1_interval, retr_t2_interval)</function>
	</title>
	<para>
		Sets the retr_t1_interval and retr_t2_interval for the current
		transaction or for transactions created during the same script 
		invocation, after calling this function.
		If one of the parameters is 0, it's value won't be changed.
		If the transaction is already created (e.g called after
		 <function>t_relay()</function> or in an onreply_route) all the
		 existing branches will have their retransmissions intervals updated 
		 on-the-fly:
		 if the retransmission interval for the branch has not yet reached T2
		  the interval will be reset to retr_t1_interval, else to 
		  retr_t2_interval. Note that the change will happen after the current
		  interval expires (after the next retransmission, the next-next 
		  retransmission will take place at retr_t1_interval or 
		  retr_t2_interval).
		 All new branches of the same transaction will start with the new 
		 values.
		 This function will work even if it's called in the script before
		a transaction creating function (e.g.: t_set_retr(500, 4000);
		t_relay()). All new transaction created after this function call, 
		during the same script invocation will use the new values.
		Note that this function will work only if tm is compile with
		 -DTM_DIFF_RT_TIMEOUT (which increases every transaction size with
		 4 bytes).
	</para>
	<para>Meaning of the parameters is as follows:</para>
	<itemizedlist>
	    <listitem>
		<para><emphasis>retr_t1_interval</emphasis> - new T1 retransmission
			interval (in milliseconds). See also
			<varname>retr_t1_timeout</varname>.
		</para>
		<para><emphasis>retr_t2_interval</emphasis> - new T2 (or maximum) 
			retransmission interval (in milliseconds). See also
			<varname>retr_t2_timeout</varname>.
		</para>
	    </listitem>
	</itemizedlist>
	<example>
	    <title><function>t_set_retr</function> usage</title>
	    <programlisting>
...
route { 
	t_set_retr(250, 0); # set only T1 to 250 ms
	t_on_branch("1");
	t_relay(); 
} 

branch_route[1] {
	# if we are calling the a remote pstn, extend T1 and decrease T2
	# for all the branches
	if (uri=~"sip:[0-9]+"){
		t_set_retr(500, 2000); 
	}
}
	    </programlisting>
	</example>
	</section>

	<section id="t_branch_timeout">
	<title>
	    <function>t_branch_timeout()</function>
	</title>
	<para>
		Returns true if the failure route is executed for a branch that did
		timeout. It can be used only from the 
		<emphasis>failure_route</emphasis>.
	</para>
	<example>
	    <title><function>t_branch_timeout</function> usage</title>
	    <programlisting>
...
failure_route[0]{ 
	if (t_branch_timeout()){
		log("timeout\n");
		# ... 
	}
} 
	    </programlisting>
	</example>
	</section>

<section id="t_branch_replied">
	<title>
	    <function>t_branch_replied()</function>
	</title>
	<para>
		Returns true if the failure route is executed for a branch that did
		receive at least one reply in the past (the "current" reply is not 
		taken into account). It can be used only from the 
		<emphasis>failure_route</emphasis>.
	</para>
	<example>
	    <title><function>t_branch_replied</function> usage</title>
	    <programlisting>
...
failure_route[0]{ 
	if (t_branch_timeout()){
		if (t_branch_replied())
			log("timeout after receiving a reply (no answer?)\n");
		else
			log("timeout, remote side seems to be down\n");
		# ... 
	}
} 
	    </programlisting>
	</example>
	</section>

<section id="t_any_timeout">
	<title>
	    <function>t_any_timeout()</function>
	</title>
	<para>
		Returns true if at least one of the current transactions branches
		did timeout.
	</para>
	<example>
	    <title><function>t_any_timeout</function> usage</title>
	    <programlisting>
...
failure_route[0]{ 
	if (!t_branch_timeout()){
		if (t_any_timeout()){
			log("one branch did timeout\n");
			sl_send_reply("408", "Timeout");
		}
	}
} 
	    </programlisting>
	</example>
	</section>

<section id="t_any_replied">
	<title>
	    <function>t_any_replied()</function>
	</title>
	<para>
		Returns true if at least one of the current transactions branches
		did receive some reply in the past. If called from a failure or
		onreply route, the "current" reply is not taken into account.
	</para>
	<example>
	    <title><function>t_any_replied</function> usage</title>
	    <programlisting>
...
onreply_route[0]{ 
	if (!t_any_replied()){
		log("first reply received\n");
		# ...
	}
} 
	    </programlisting>
	</example>
</section>

<section id="t_grep_status">
	<title>
	    <function>t_grep_status("code")</function>
	</title>
	<para>
		Returns true if "code" is the final reply received (or locally
		 generated) in at least one of the current transactions branches.
	</para>
	<example>
	    <title><function>t_grep_status</function> usage</title>
	    <programlisting>
...
onreply_route[0]{ 
	if (t_grep_status("486")){
		/* force a 486 reply, even if this is not the winning branch */
		t_reply("486", "Busy");
	}
} 
	    </programlisting>
	</example>
</section>

<section id="t_is_canceled">
	<title>
	    <function>t_is_canceled()</function>
	</title>
	<para>
		Returns true if the current transaction was canceled.
	</para>
	<example>
	    <title><function>t_is_canceled</function> usage</title>
	    <programlisting>
...
failure_route[0]{ 
	if (t_is_canceled()){
		log("transaction canceled\n");
		# ...
	}
} 
	    </programlisting>
	</example>
	</section>

    <section id="t_relay_cancel">
	<title>
	    <function>t_relay_cancel()</function>
	</title>
	<para>
		Forwards the CANCEL if the corresponding INVITE transaction
		exists. The function is supposed to be used at the very
		beginning of the script, because the CANCELs can be caught
		and the rest of the script can be bypassed this way. Do not disable
		<varname>reparse_invite</varname> module parameter, and call
		<varname>t_relay_cancel()</varname> right after the sanity tests.
	</para>
	<para>
		Return value is 0 (drop) if the corresponding INVITE was found
		and the CANCELs were successfully sent to the pending branches,
		true if the INVITE was not found, and false in case of any error.
	</para>
	<example>
	    <title><function>t_relay_cancel</function> usage</title>
	    <programlisting>

if (method == CANCEL) {
	if (!t_relay_cancel()) {  # implicit drop if relaying was successful,
                                  # nothing to do

		# corresponding INVITE transaction found but error occurred
		sl_reply("500", "Internal Server Error");
		drop;
	}
	# bad luck, corresponding INVITE transaction is missing,
	# do the same as for INVITEs
}
	    </programlisting>
	</example>
    </section>

    <section id="t_drop_replies">
	<title>
	    <function>t_drop_replies()</function>
	</title>
	<para>
		Drops all the previously received replies in failure_route
		block to make sure that none of them is picked up again.
		Works only if a new branch is added to the transaction,
		or it is explicitly replied in the script!
	</para>
	<example>
	    <title><function>t_drop_replies()</function> usage</title>
	    <programlisting>
...
failure_route[0]{ 
	if (t_check_status("5[0-9][0-9]")){
		# I do not like the 5xx responses,
		# so I give another chance to "foobar.com",
		# and I drop all the replies to make sure that
		# they are not forwarded to the caller.
		t_drop_replies();
		
		rewritehostport("foobar.com");
		append_branch();
		t_relay();
	}
} 
	    </programlisting>
	</example>
    </section>

    <section id="t_save_lumps">
	<title>
	    <function>t_save_lumps()</function>
	</title>
	<para>
		Forces the modifications of the processed SIP message
		to be saved in shared memory before t_relay() is called.
		The new branches which are created in failure_route will
		contain the same modifications, and any other modification
		after t_save_lumps() will be lost.
	</para>
	<para>
		Note that t_relay() automatically saves the modifications
		when it is called the first time, there is no need for
		t_save_lumps() unless message changes between t_save_lumps()
		and t_relay() must not be propagated to failure_route.
	</para>
	<para>
		The transaction must be created by t_newtran() before
		calling t_save_lumps().
	</para>
	<example>
	    <title><function>t_save_lumps()</function> usage</title>
	    <programlisting>
route {
	...
	t_newtran();
	append_hf("hf1: my first header\r\n");
	...
	t_save_lumps();
	append_hf("hf2: my second header\r\n");
	...
	t_on_failure("1");
	t_relay();
}

failure_route[1] {
	append_branch();
	append_hf("hf3: my third header\r\n");
	#
	# This branch contains hf1 and hf3, but does
	# not contain hf2 header.
	# hf2 would be also present here without
	# t_save_lumps().
	...
	t_relay();
}
	    </programlisting>
	</example>
    </section>
</section>