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kamailio/modules/tm/doc/functions.xml

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE section PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<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>
<function>t_relay_to_sctp(ip, port)</function>
<function>t_relay_to_sctp()</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 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 look-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()</function>
<function>t_forward_nonack(ip, port)</function>
<function>t_forward_nonack_udp(ip, port)</function>
<function>t_forward_nonack_tcp(ip, port)</function>
<function>t_forward_nonack_tls(ip, port)</function>
<function>t_forward_nonack_sctp(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, its 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>
<para>
See also:
<varname>fr_timer</varname>,
<varname>fr_inv_timer</varname>,
<function>t_reset_fr()</function>.
</para>
<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_reset_fr">
<title>
<function>t_reset_fr()</function>
</title>
<para>
Resets the <varname>fr_inv_timer</varname> and
<varname>fr_timer</varname> for the current transaction to the default
values (set using the tm module parameters
<varname>fr_inv_timer</varname> and <varname>fr_timer</varname>).
</para>
<para>
It will effectively cancel any previous calls to
<function>t_set_fr</function> for the same transaction.
</para>
<para>
See also: <varname>fr_timer</varname>,
<varname>fr_inv_timer</varname>,
<function>t_set_fr</function>.
</para>
<example>
<title><function>t_reset_fr</function> usage</title>
<programlisting>
...
route {
...
t_reset_fr();
...
}
</programlisting>
</example>
</section>
<section id="t_set_max_lifetime">
<title>
<function>t_set_max_lifetime(inv_lifetime, noninv_lifetime)</function>
</title>
<para>
Sets the maximum lifetime for the current INVITE or non-INVITE
transaction, or for transactions created during the same script
invocation, after calling this function (that's why it takes values
for both INVITE and non-INVITE).
If one of the parameters is 0, its value won't be changed.
</para>
<para>
It works as a per transaction <varname>max_inv_lifetime</varname> or
<varname>max_noninv_lifetime</varname>.
</para>
<para>Meaning of the parameters is as follows:</para>
<itemizedlist>
<listitem>
<para><emphasis>inv_lifetime</emphasis> - maximum INVITE transaction
lifetime (in milliseconds). See also
<varname>max_inv_lifetime</varname>.
</para>
<para><emphasis>noninv_lifetime</emphasis> - maximum non-INVITE
transaction lifetime (in milliseconds).
See also <varname>max_noninv_lifetime</varname>.
</para>
</listitem>
</itemizedlist>
<para>
See also: <varname>max_inv_lifetime</varname>,
<varname>max_noninv_lifetime</varname>,
<function>t_reset_max_lifetime</function>.
</para>
<example>
<title><function>t_set_max_lifetime</function> usage</title>
<programlisting>
...
route {
if (src_ip=1.2.3.4)
t_set_max_lifetime(120000, 0); # set only max_inv_lifetime to 120s
else
t_set_max_lifetime(90000, 15000); # set the maximum lifetime to 90s if
# the current transaction is an
# INVITE and to 15s if not
}
</programlisting>
</example>
</section>
<section id="t_reset_max_lifetime">
<title>
<function>t_reset_max_lifetime()</function>
</title>
<para>
Resets the the maximum lifetime for the current INVITE or non-INVITE
transaction to the default value (set using the tm module parameter
<varname>max_inv_lifetime</varname> or
<varname>max_noninv_lifetime</varname>).
</para>
<para>
It will effectively cancel any previous calls to
<function>t_set_max_lifetime</function> for the same transaction.
</para>
<para>
See also: <varname>max_inv_lifetime</varname>,
<varname>max_noninv_lifetime</varname>,
<function>t_set_max_lifetime</function>.
</para>
<example>
<title><function>t_reset_max_lifetime</function> usage</title>
<programlisting>
...
route {
...
t_reset_max_lifetime();
...
}
</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>
<para>
See also:
<varname>retr_timer1</varname>,
<varname>retr_timer2</varname>,
<function>t_reset_retr()</function>.
</para>
<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_reset_retr">
<title>
<function>t_reset_retr()</function>
</title>
<para>
Resets the <varname>retr_timer1</varname> and
<varname>retr_timer2</varname> for the current transaction to the
default values (set using the tm module parameters
<varname>retr_timer1</varname> and <varname>retr_timer2</varname>).
</para>
<para>
It will effectively cancel any previous calls to
<function>t_set_retr</function> for the same transaction.
</para>
<para>
See also: <varname>retr_timer1</varname>,
<varname>retr_timer2</varname>,
<function>t_set_retr</function>.
</para>
<example>
<title><function>t_reset_retr</function> usage</title>
<programlisting>
...
route {
...
t_reset_retr();
...
}
</programlisting>
</example>
</section>
<section id="t_set_auto_inv_100">
<title>
<function>t_set_auto_inv_100(0|1)</function>
</title>
<para>
Switch automatically sending 100 replies to INVITEs on/off on a
per transaction basis. It overrides the
<varname>auto_inv_100</varname> value for the current transaction.
</para>
<para>
See also: <varname>auto_inv_100</varname>.
</para>
<example>
<title><function>t_set_auto_inv_100</function> usage</title>
<programlisting>
...
route {
...
if (src_ip==1.2.3.0/24)
t_set_auto_inv_100(0); # turn off automatic 100 replies
...
}
</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_is_expired">
<title>
<function>t_is_expired()</function>
</title>
<para>
Returns true if the current transaction has already been expired,
i.e. the max_inv_lifetime/max_noninv_lifetime interval has already
elapsed.
</para>
<example>
<title><function>t_is_expired</function> usage</title>
<programlisting>
...
failure_route[0]{
if (t_is_expired()){
log("transaction expired\n");
# There is no point in adding a new branch.
}
}
</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_lookup_cancel">
<title>
<function>t_lookup_cancel()</function>,
<function>t_lookup_cancel(1)</function>
</title>
<para>
Returns true if the corresponding INVITE transaction exists
for a CANCEL request. The function can be called at the beginning
of the script to check whether or not the CANCEL can be immediately
forwarded bypassing the rest of the script. Note however that
<function>t_relay_cancel</function> includes
<function>t_lookup_cancel</function> as well, therefore it is not
needed to explicitly call this function unless something has to be
logged for example.
</para>
<para>
If the function parameter (optional) is set to 1, the message flags
are overwritten with the flags of the INVITE. isflagset() can be used
to check the flags of the previously forwarded INVITE in this case.
</para>
<example>
<title><function>t_lookup_cancel</function> usage</title>
<programlisting>
if (method == CANCEL) {
if (t_lookup_cancel()) {
log("INVITE transaction exists");
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([mode])</function>
</title>
<para>
Drops all the previously received replies in failure_route
block to make sure that none of them is picked up again.
</para>
<para>
The parameter 'mode' controls which replies are dropped: 'a'
or missing - all replies are dropped; 'l' - replies received for
last set of branches are dropped; 'n' - no reply is dropped.
</para>
<para>
Dropping replies 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>
<title>
<function moreinfo="none">t_load_contacts()</function>
</title>
<para>
This is the first of the two functions that can be used to implement
serial/parallel forking based on the q value of individual branches
in a destination set.
</para>
<para>
The function <function>t_load_contacts()</function> takes all
branches from the current destination set and encodes them into the
AVP whose name or ID is configured with the
parameter <varname>contacts_avp</varname>. Note that you have to
configure this parameter before you can use the function, the
parameter is set to NULL by default, which disables the function.
</para>
<para>
If the destination set contains only one branch (the Request-URI) or
if all branches have the same q value then the function does nothing
to minimize performance impact. In such case all branches should be
tried in parallel and that is the default mode of operation of
functions like <function>t_relay()</function>, so there is no need
to create the AVP or sort the branches.
</para>
<para>
If the current destination set contains more than one branch and not
all branches have the same q value then the function sorts them
according to the increasing value of the q parameter. The resulting
sorted list of branches is then encoded into the AVP.
</para>
<para>
The q parameter contains a value from a range of 0 to 1.0 and it
expresses relative preferrence of the branch among all branches in
the destination set. The higher the q value the more preferrence the
user agent gave to the branch. Branches with higher q values will be
tried first when serial forking takes place.
</para>
<para>
After that the function clears all branches and you have to
call <function>t_next_contacts</function> to retrieve them sorted
according to their q value. Note that if you
use <function>t_load_contacts</function> then you also have to
use <function>t_next_contacts</function> before
calling <function>t_relay</function>.
</para>
<para>
The AVP created by the function may contain multiple values, with
one encoded branch per value. The first value will contain the
branch with the highest q value. Each value contains the
Request-URI, the destination URI, the path vector, the outgoing
socket description and branch flags. All these fields are delimited
with the LF character.
</para>
<para>
The function returns 1 if loading of contacts succeeded or there was
nothing to do. Returns -1 on error (see syslog).
</para>
<para>
This function can be used from REQUEST_ROUTE.
</para>
<example>
<title><function>t_load_contacts</function> usage</title>
<programlisting format="linespecific">
...
if (!t_load_contacts()) {
sl_send_reply("500", "Server Internal Error - Cannot load contacts");
exit;
};
...
</programlisting>
</example>
</section>
<section>
<title>
<function moreinfo="none">t_next_contacts()</function>
</title>
<para>
The function <function>t_next_contacts</function> is the second of
the two functions that can be used to implement serial/parallel
forking based on the q value of individual branches in a destination
set.
</para>
<para>
This function takes the contact_avp created
by <function>t_load_contacts</function> and extracts
branches with
highest q value from it into the destination set when
called for the
first time. When you call the function second time it extracts
branches with lower q value, and so on until all branches have been
extracted. At each call, Request URI is rewritten with
first branch and the remaining branches (if any) are
added as branches. Then these "used" branches are remove
from the AVP.
</para>
<para>
The function does nothing if there are
no <varname>contact_avp</varname> values.
</para>
<para>
The function returns 1 if the AVP was not empty and a
destination set was successfully added,
returns -2 if contact_avp was empty and thus there was
nothing to do, and returns -1 in case of an error (see
syslog).
This function can be used from REQUEST_ROUTE and FAILURE_ROUTE.
</para>
<para>
Note that if use use <function>t_load_contacts</function>
and <function>t_next_contacts</function> functions then you should
also set the value of <varname>restart_fr_on_each_reply</varname>
parameter to 0. If you do not do that then it can happen that a
broken user agent that retransmits 180 periodically will keep
resetting the fr_inv_timer value and serial forking never happens.
</para>
<para>
Before calling t_relay(), you can check if the
previous call of next_contacts() consumed all branches
by checking if contact_avp is not anymore set. Based on
that test, you can then use t_set_fr() function to set
timers according to your needs.
</para>
<example>
<title><function>t_next_contacts</function> usage</title>
<programlisting format="linespecific">
...
# First call after t_load_contacts() when transaction does not exist yet
# and contacts should be available
if (!t_next_contacts()) {
sl_send_reply("500", "Server Internal Error - Cannot get contacts");
} else {
t_relay();
};
...
# Following call, when transaction exists and there may or may not be
# contacts left
if (!t_next_contacts()) {
t_reply("408", "Request Timeout");
} else {
t_relay();
};
...
</programlisting>
</example>
</section>
<section id="t_check_trans">
<title>
<function>t_check_trans()</function>
</title>
<para>
<function>t_check_trans()</function> can be used to quickly check if
a message belongs or is related to a transaction. It behaves
differently for different types of messages:
<itemizedlist>
<listitem>
<para>For a SIP Reply it returns true if the reply belongs to
an existing transaction and false otherwise.</para>
</listitem>
<listitem>
<para>For a CANCEL it behaves exactly as
<function>t_lookup_cancel()</function>: returns true if a
corresponding INVITE transaction exists for the CANCEL and
false otherwise.</para>
</listitem>
<listitem>
<para>For ACKs to negative replies or for ACKs to local
transactions it will terminate the script if the ACK belongs
to a transaction (it would make very little sense to process
an ACK to a negative reply for an existing transaction in
some other way then to simply pass it to tm) or return false
if not.</para>
</listitem>
<listitem>
<para>For end-to-end ACKs (ACKs to 2xx responses for forwarded
INVITE transactions) it will return true if the corresponding
INVITE transaction is found and still active and false if not.
</para>
<note>
<para>
Note that the e2e ACK matching is more of a hint
then a certainty. A delayed e2e ACK might arrive after the
transaction wait time elapses, when the INVITE transaction no
longer exists and thus would not match anything. There are
also cases when tm would not keep all the information needed
for e2e ACK matching (since this is not needed for a statefull
proxy and it requires additional memory, tm will not keep this
information unless needed by some other module or callbacks).
</para>
</note>
</listitem>
<listitem>
<para>For other requests (non ACKs and non CANCELs), it will
terminate the script for retransmissions and return false for
new requests (for which no transaction exists yet).</para>
</listitem>
</itemizedlist>
</para>
<note><para>
An important difference from kamailio version is that for an ACK to
negative reply or for a local transaction, the script execution will be
immediately stopped and the message handled by tm, instead of returning
true.
</para></note>
<para><function>t_check_trans()</function> functionality for requests,
except for the e2e ACK matching, can be replicated in the script
using <function>t_lookup_cancel()</function> and
<function>t_lookup_request()</function>.
</para>
<para>See also: <function>t_lookup_request()</function>,
<function>t_lookup_cancel()</function>.
</para>
<example>
<title><function>t_check_trans</function> usage</title>
<programlisting>
if ( method == "CANCEL" &amp;&amp; !t_check_trans())
sl_reply("403", "cancel out of the blue forbidden");
# note: in this example t_check_trans() can be replaced by t_lookup_cancel()
</programlisting>
</example>
</section>
<section id="t_set_disable_6xx">
<title>
<function>t_set_disable_6xx(0|1)</function>
</title>
<para>
Turn off/on 6xx replies special rfc conformant handling on a per
transaction basis. If turned off
(<function>t_set_disable_6xx("1")</function>) 6XXs will be treated
like normal replies.
</para>
<para>
It overrides the <varname>disable_6xx_block</varname> value for
the current transaction.
</para>
<para>
See also: <varname>disable_6xx_block</varname>.
</para>
<example>
<title><function>t_set_disable_6xx</function> usage</title>
<programlisting>
...
route {
...
if (src_ip==1.2.3.4) # bad user agent that sends 603
t_set_disable_6xx(1); # turn off 6xx special handling
...
}
</programlisting>
</example>
</section>
<section id="t_set_disable_failover">
<title>
<function>t_set_disable_failover(0|1)</function>
</title>
<para>
Turn off/on dns failover on a per transaction basis.
</para>
<para>
See also: <varname>use_dns_failover</varname>.
</para>
<example>
<title><function>t_set_disable_failover</function> usage</title>
<programlisting>
...
route {
...
if (uri=~"@foo.bar$")
t_set_disable_failover(1); # turn off dns failover
...
}
</programlisting>
</example>
</section>
<section id="t_replicate">
<title>
<function>t_replicate(params)</function>
</title>
<para>
Replicate the SIP request to a specific address.
</para>
<para>
There are several function prototypes:
<itemizedlist>
<listitem><para>
<function>t_replicate(uri)</function>,
</para></listitem>
<listitem><para>
<function>t_replicate(host, port)</function>,
</para></listitem>
<listitem><para>
<function>t_replicat_udp(host, port)</function>
</para></listitem>
<listitem><para>
<function>t_replicate_tcp(host, port)</function>
</para></listitem>
<listitem><para>
<function>t_replicate_tls(host, port)</function>
</para></listitem>
<listitem><para>
<function>t_replicate_sctp(host, port)</function>
</para></listitem>
<listitem><para>
<function>t_replicate_to(proto, hostport)</function>
</para></listitem>
</itemizedlist>
</para>
<para>Meaning of the parameters is as follows:</para>
<itemizedlist>
<listitem>
<para><emphasis>uri</emphasis> - SIP URI where the message should be sent.
It can be given via a script variable.
</para>
</listitem>
<listitem>
<para><emphasis>host</emphasis> - host address where the message should be sent.
</para>
</listitem>
<listitem>
<para><emphasis>port</emphasis> - port number.
</para>
</listitem>
<listitem>
<para><emphasis>proto</emphasis> - transport protocol to be used.
</para>
</listitem>
<listitem>
<para><emphasis>hostport</emphasis> - address in "host:port" format. It can be
given via an AVP.
</para>
</listitem>
</itemizedlist>
<example>
<title><function>t_replicate</function> usage</title>
<programlisting>
...
# sent to 1.2.3.4:5060 over tcp
t_replicate("sip:1.2.3.4:5060;transport=tcp");
# sent to 1.2.3.4:5061 over tls
$var(h) = "1.2.3.4:5061";
t_replicate("sip:$var(h);transport=tls");
# sent to 1.2.3.4:5060 over udp
t_replicate_to_udp("1.2.3.4", "5060");
...
</programlisting>
</example>
</section>
<section id="t_relay_to">
<title>
<function>t_relay_to(proxy, flags)</function>
</title>
<para>
Forward the SIP request to a specific address, controlling internal
behavior via flags.
</para>
<para>
There are several function prototypes:
<itemizedlist>
<listitem><para>
<function>t_relay_to()</function>,
</para></listitem>
<listitem><para>
<function>t_relay_to(proxy)</function>,
</para></listitem>
<listitem><para>
<function>t_relay_to(flags)</function>
</para></listitem>
<listitem><para>
<function>t_relay_to(proxy, flags)</function>
</para></listitem>
</itemizedlist>
</para>
<para>Meaning of the parameters is as follows:</para>
<itemizedlist>
<listitem>
<para><emphasis>proxy</emphasis> - address where the request should
be sent. Format is: "proto:host:port" - any of proto or port can be
ommitted, along with the semicolon after or before.
</para>
</listitem>
<listitem>
<para><emphasis>flags</emphasis> - bitmask integer value to control
the internal behavior. Bits can be:
</para>
<itemizedlist>
<listitem>
<para><emphasis>0x01</emphasis> - do not generate 100 reply.
</para>
</listitem>
<listitem>
<para><emphasis>0x02</emphasis> - do not generate reply on internal
error (NOTE: has no effect anymore).
</para>
</listitem>
<listitem>
<para><emphasis>0x04</emphasis> - disable dns failover.
</para>
</listitem>
</itemizedlist>
</listitem>
</itemizedlist>
<example>
<title><function>t_replicate</function> usage</title>
<programlisting>
...
# sent to 1.2.3.4:5060 over tcp
t_relay_to("tcp:1.2.3.4:5060");
# sent to 1.2.3.4 over tls
t_relay_to("tls:1.2.3.4");
# sent to dst URI or R-URI without a 100 reply
t_relay_to("0x01");
...
</programlisting>
</example>
</section>
<section id="t_set_no_e2e_cancel_reason">
<title>
<function>t_set_no_e2e_cancel_reason(0|1)</function>
</title>
<para>
Enables/disables reason header (RFC 3326) copying from the triggering
received CANCEL to the generated hop-by-hop CANCEL. 0 enables and
1 disables.
</para>
<para>
It overrides the <varname>e2e_cancel_reason</varname> setting (module
parameter) for the current transaction.
</para>
<para>
See also: <varname>e2e_cancel_reason</varname>.
</para>
<example>
<title><function>t_set_no_e2e_cancel_reason</function> usage</title>
<programlisting>
...
route {
...
if (src_ip!=10.0.0.0/8) # don't trust CANCELs from the outside
t_set_no_e2e_cancel_reason(1); # turn off CANCEL reason header copying
...
}
</programlisting>
</example>
</section>
</section>