fr_timer (integer)
fr_inv_timer (integer)
max_inv_lifetime (integer)
max_noninv_lifetime (integer)
wt_timer (integer)
delete_timer (integer)
retr_timer1 (integer)
retr_timer2 (integer)
noisy_ctimer (integer)
restart_fr_on_each_reply (integer)
auto_inv_100 (integer)
auto_inv_100_reason (string)
unix_tx_timeout (integer)
aggregate_challenges (integer)
reparse_invite (integer)
ac_extra_hdrs (string)
blst_503 (integer)
blst_503_def_timeout (integer)
blst_503_min_timeout (integer)
blst_503_max_timeout (integer)
blst_methods_add (unsigned integer)
blst_methods_lookup (unsigned integer)
cancel_b_method (integer)
reparse_on_dns_failover (integer)
on_sl_reply (string)
contacts_avp (string)
fr_timer_avp (string)
fr_inv_timer_avp (string)
unmatched_cancel (string)
ruri_matching (integer)
via1_matching (integer)
pass_provisional_replies (integer)
default_code (integer)
default_reason (string)
disable_6xx_block (integer)
local_ack_mode (integer)
failure_reply_mode (integer)
faked_reply_prio (integer)
local_cancel_reason (boolean)
e2e_cancel_reason (boolean)
t_relay([host, port])
t_relay_to_udp([ip, port])
t_relay_to_tcp([ip, port])
t_relay_to_tls([ip, port])
t_relay_to_sctp([ip, port])
t_on_failure(failure_route)
t_on_reply(onreply_route)
t_on_branch(branch_route)
append_branch()
t_newtran()
t_reply(code, reason_phrase)
t_lookup_request()
t_retransmit_reply()
t_release()
t_forward_nonack([ip, port])
t_forward_nonack_udp(ip, port)
t_forward_nonack_tcp(ip, port)
t_forward_nonack_tls(ip, port)
t_forward_nonack_sctp(ip, port)
t_set_fr(fr_inv_timeout [, fr_timeout])
t_reset_fr()
t_set_max_lifetime(inv_lifetime, noninv_lifetime)
t_reset_max_lifetime()
t_set_retr(retr_t1_interval, retr_t2_interval)
t_reset_retr()
t_set_auto_inv_100(0|1)
t_branch_timeout()
t_branch_replied()
t_any_timeout()
t_any_replied()
t_grep_status("code")
t_is_canceled()
t_is_expired()
t_relay_cancel()
t_lookup_cancel([1])
t_drop_replies([mode])
t_save_lumps()
t_load_contacts()
t_next_contacts()
t_check_trans()
t_set_disable_6xx(0|1)
t_set_disable_failover(0|1)
t_replicate(params)
t_relay_to(proxy, flags)
t_set_no_e2e_cancel_reason(0|1)
register_tmcb(cb_type, cb_func)
load_tm(*import_structure)
int t_suspend(struct sip_msg *msg,
unsigned int *hash_index, unsigned int *label)
int t_continue(unsigned int hash_index, unsigned int label,
struct action *route)
int t_cancel_suspend(unsigned int hash_index, unsigned int label)
TM module enables stateful processing of SIP transactions. The main use of stateful logic, which is costly in terms of memory and CPU, is some services inherently need state. For example, transaction-based accounting (module acc) needs to process transaction state as opposed to individual messages, and any kinds of forking must be implemented statefully. Other use of stateful processing is it trading CPU caused by retransmission processing for memory. That makes however only sense if CPU consumption per request is huge. For example, if you want to avoid costly DNS resolution for every retransmission of a request to an unresolvable destination, use stateful mode. Then, only the initial message burdens server by DNS queries, subsequent retransmissions will be dropped and will not result in more processes blocked by DNS resolution. The price is more memory consumption and higher processing latency.
From user's perspective, there are these major functions : t_relay, t_relay_to_udp and t_relay_to_tcp. All of them setup transaction state, absorb retransmissions from upstream, generate downstream retransmissions and correlate replies to requests. t_relay forwards to current URI (be it original request's URI or a URI changed by some of URI-modifying functions, such as sethost). t_relay_to_udp and t_relay_to_tcp forward to a specific address over UDP or TCP respectively.
In general, if TM is used, it copies clones of received SIP messages in shared memory. That costs the memory and also CPU time (memcpys, lookups, shmem locks, etc.) Note that non-TM functions operate over the received message in private memory, that means that any core operations will have no effect on statefully processed messages after creating the transactional state. For example, calling record_route after t_relay is pretty useless, as the RR is added to privately held message whereas its TM clone is being forwarded.
TM is quite big and uneasy to program--lot of mutexes, shared memory access, malloc and free, timers--you really need to be careful when you do anything. To simplify TM programming, there is the instrument of callbacks. The callback mechanisms allow programmers to register their functions to specific event. See t_hooks.h for a list of possible events.
Other things programmers may want to know is UAC--it is a very simplistic code which allows you to generate your own transactions. Particularly useful for things like NOTIFYs or IM gateways. The UAC takes care of all the transaction machinery: retransmissions , FR timeouts, forking, etc. See t_uac prototype in uac.h for more details. Who wants to see the transaction result may register for a callback.
Several Kamailio (OpenSER) TM module functionalities are now implemented in the TMX module: “modules_k/tmx”. Check it to see if what you are looking for is there.
A single SIP INVITE request may be forked to multiple destinations. We call the set of all such destinations a destination set. Individual elements within the destination sets are called branches. The script writer can add URIs to the destination set from the configuration file, or they can be loaded from the user location database, each registered contact then becomes one branch in the destination set.
The default behavior of the tm module, if it encounters a SIP message
with multiple branches in the destination set, it to forward the SIP
message to all the branches in parallel. That means it sends the
message to all the branch destinations before it waits for replies
from any of them. This is the default behavior if you
call t_relay() and similar functions without
anything else.
Another approach of handling multiple branches in a destination set it serial forking. When configured to do serial forking, the server takes the first branch out of the destination set, forwards the message to its destination and waits for a reply or timeout. Only after a reply has been received or the timeout occurred, the server takes another destination from the destination set and tries again, until it receives a positive final reply or until all branches from the destination set have been tried.
Yet another, more sophisticated, way of handling multiple branches is
combined serial/parallel forking, where individual branches within the
destination set are assigned priorities. The order in which individual
branches are tried is then determined by their relative priority
within the destination set. Branches can be tried sequentially in the
descending priority order and all branches that have the same priority
can be tried in parallel. Such combined serial/parallel forking can be
achieved in the tm module with the help of
functions t_load_contacts()
and t_next_contacts().
Every branch in the destination set is assigned a priority number, also known as the q value. The q value is a floating point number in a range 0 to 1.0. The higher the q value number, the more priority is the particular branch in the destination set is given. Branches with q value 1.0 have maximum priority, such branches should be always tried first in serial forking. Branches with q value 0 have the lowest priority and they should by tried after all other branches with higher priority in the destination set.
As an example, consider the following simple configuration file. When
the server receives an INVITE, it creates four branches for it with
usernames A through D and then forwards the request
using t_relay():
route {
seturi("sip:a@example.com");
append_branch("sip:b@example.com");
append_branch("sip:c@example.com");
append_branch("sip:d@example.com");
t_relay();
break;
}
With this configuratin the server forwards the request to all four
branches at once, performing parallel forking described above. We did
not set the q value for individual branches in this example but we can
do that by slightly modifying the arguments given
to append_branch():
route {
seturi("sip:a@example.com");
append_branch("sip:b@example.com", "0.5");
append_branch("sip:c@example.com", "0.5");
append_branch("sip:d@example.com", "1.0");
t_relay();
break;
}
Here we assigned q value 0.5 to branches B and C and q value 1.0 to
branch D. We did not specify any q value for branch A and in that case
it is assumed that its q value is the lowest from all branches within
the destination set. If you try to run this example again, you will
figure out that nothing changed, t_relay() still
forward the message to all branches in parallel.
We now want to implement the combined serial/parallel forking. Branch D should be tried first, because its q value is 1.0. Branches B and C should be tried in parallel, but only after D finishes. Branch A should be tried after B and C finished, because its q value (the default) is the lowest of all. To do that, we need to introduce two new functions into our example and one tm module parameter:
modparam("tm", "contacts_avp", "tm_contacts");
route {
seturi("sip:a@example.com");
append_branch("sip:b@example.com", "0.5");
append_branch("sip:c@example.com", "0.5");
append_branch("sip:d@example.com", "1.0");
t_load_contacts();
t_next_contacts();
t_relay();
break;
}
First of all, the tm module parameter is mandatory if the two new
functions are used. Function t_load_contacts()
takes all branches from the destination set, sorts them according to
their q values and stores them in the AVP configured in the modparam.
The function also clears the destination set, which means that it
removes all branches configured before
with seturi()
and append_branch().
Function t_next_contacts() takes the AVP created
by the previous function and extract the branches with highest q
values from it. In our example it is branch D. That branch is then put
back into the destination set and when the script finally
reaches t_relay(), the destination set only
contains branch D and the request will be forwarded there.
We achieved the first step of serial forking, but this is not sufficient. Now we also need to forward to other branches with lower priority values when branch D finishes. To do that, we need to extend the configuration file again and introduce a failure_route section:
modparam("tm", "contacts_avp", "tm_contacts");
route {
seturi("sip:a@example.com");
append_branch("sip:b@example.com", "0.5");
append_branch("sip:c@example.com", "0.5");
append_branch("sip:d@example.com", "1.0");
t_load_contacts();
t_next_contacts();
t_on_failure("serial");
t_relay();
break;
}
failure_route["serial"]
{
if (!t_next_contacts()) {
exit;
}
t_on_failure("serial");
t_relay();
}
The failure_route section will be executed when branch D finishes. It
executes t_next_contacts() again and this time
the function retrieves branches B and C from the AVP and adds them to
the destination set. Here we need to check the return value of the
function, because a negative value indicates that there were no more
branches, in that case the failure_route should just terminate and
forward the response from branch D upstream.
If t_next_contact() returns a positive value then
we have more new branches to try and we need to setup the
failure_route again and call t_relay(). In our
example the request will now be forwarded to branches B and C in
paralell, because they were both added to the destination set
by t_next_contacts() at the same time.
When branches B and C finish, the failure_route block is executed
again, this time t_next_contacts() puts the final
branch A into the destination set and t_relay()
forwards the request there.
And that's the whole example, we achieved combined serial/parallel
forking based on the q value of individual branches. In real-world
configuration files the script writer would need to check the return
value of all functions and restart_fr_on_each_reply. Also the destination
set would not be configured directly in the configuration file, but
can be retrieved from the user location database, for example. In that
case registered contacts will be stored in the destination set as
branches and their q values (provided by UAs) will be used.
Possibly, performance could be improved by not parsing non-INVITEs, as they do not be replied with 100, and do not result in ACK/CANCELs, and other things which take parsing. However, we need to rethink whether we don't need parsed headers later for something else. Remember, when we now conserver a request in sh_mem, we can't apply any pkg_mem operations to it any more. (that might be redesigned too).
Another performance improvement may be achieved by not parsing CSeq in replies until reply branch matches branch of an INVITE/CANCEL in transaction table.
t_replicate should be done more
cleanly--Vias, Routes, etc. should be removed from a
message prior to replicating it (well, does not matter any
longer so much as there is a new replication module).
Timer which hits if no final reply for a request or ACK for a negative INVITE reply arrives (in milliseconds).
Default value is 30000 ms (30 seconds).
See also: t_set_fr(),
max_noninv_lifetime.
Timer which hits if no final reply for an INVITE arrives after a provisional message was received (in milliseconds).
Note: this timer can be restarted when a provisional response is
received. For more details see
restart_fr_on_each_reply.
Default value is 120000 ms (120 seconds).
See also: t_set_fr(),
max_inv_lifetime.
Maximum time an INVITE transaction is allowed to be active (in
milliseconds). After this interval has passed from the transaction
creation, the transaction will be either moved into the wait state
or in the final response retransmission state, irrespective of the
transaction fr_inv_timer and
fr_timer values.
An INVITE transaction will be kept in memory for maximum:
max_inv_lifetime+fr_timer(from
the ack to the final reply wait)+wt_timer.
The main difference between this timer and
fr_inv_timer is that the
fr_inv_timer is per branch, while
max_inv_lifetime is per the whole transaction.
Even on a per branch basis fr_inv_timer could be
restarted. For example, by default if
restart_fr_on_each_reply is not cleared, the
fr_inv_timer will be restarted for each received
provisional reply. Even if restart_fr_on_each_reply
is not set the fr_inv_timer will still be restarted
for each increasing reply (e.g. 180, 181, 182, ...).
Another example when a transaction can live substantially more then its
fr_inv_timer and where
max_inv_lifetime will help is when dns failover is
used (each failed dns destination can introduce a new branch).
The default value is 180000 ms (180 seconds - the rfc3261 timer C value).
See also: max_noninv_lifetime,
t_set_max_lifetime() (allows changing
max_inv_lifetime on a per transaction
basis),
t_reset_max_lifetime
fr_timer,
wt_timer,
restart_fr_on_each_reply.
Maximum time a non-INVITE transaction is allowed to be active (in
milliseconds). After this interval has passed from the transaction
creation, the transaction will be either moved into the wait state
or in the final response retransmission state, irrespective of the
transaction fr_timer value.
It's the same as max_inv_lifetime, but for
non-INVITEs.
A non-INVITE transaction will be kept in memory for maximum:
max_noninv_lifetime+wt_timer.
The main difference between this timer and
fr_timer is that the
fr_timer is per branch, while
max_noninv_lifetime is per the whole transaction.
An example when a transaction can live substantially more then its
fr_timer and where
max_noninv_lifetime will help is when dns failover
is used (each failed dns destination can introduce a new branch).
The default value is 32000 ms (32 seconds - the rfc3261 timer F value).
See also: max_inv_lifetime,
t_set_max_lifetime() (allows changing
max_noninv_lifetime on a per transaction
basis),
t_reset_max_lifetime
fr_timer,
wt_timer.
Time for which a transaction stays in memory to absorb delayed messages after it completed (in milliseconds); also, when this timer hits, retransmission of local cancels is stopped (a puristic but complex behavior would be not to enter wait state until local branches are finished by a final reply or FR timer--we simplified).
Default value is 5000 ms (5 seconds).
Time after which a to-be-deleted transaction currently ref-ed by a process will be tried to be deleted again (in milliseconds).
Note: this parameter is obsolete for ser 2.1 (in 2.1 the transaction is deleted the moment it's not referenced anymore).
Default value is 200 milliseconds.
Initial retransmission period (in milliseconds).
Default value is 500 milliseconds.
Maximum retransmission period (in milliseconds). The retransmission
interval starts with retr_timer1 and increases until
it reaches this value. After this it stays constant at
retr_timer2.
Default value is 4000 milliseconds.
If set, INVITE transactions that time-out (FR INV timer) will be
always replied. If it's not set, the transaction has only one
branch and no response was ever received on this branch, it
will be silently dropped (no 408 reply will be generated)
This behavior is overridden if a request is forked, the transaction
has a failure route or callback, or some functionality explicitly
turned it on for a transaction (like acc does to avoid unaccounted
transactions due to expired timer).
Turn this off only if you know the client UACs will timeout and their
timeout interval for INVITEs is lower or equal than tm's
fr_inv_timer.
Default value is 1 (on).
If set (default), the fr_inv_timer for an INVITE
transaction will be restarted for each provisional reply received
(rfc3261 mandated behaviour). If not set, the
fr_inv_timer will be restarted only for the first
provisional replies and for increasing replies greater or equal 180
(e.g. 180, 181, 182, 185, ...).
Setting it to 0 is especially useful when dealing with bad UAs that continuously retransmit 180s, not allowing the transaction to timeout (and thus making impossible the implementation of certain services, like automatic voicemail after x seconds).
Default value is 1 (on).
See also: fr_inv_timer,
max_inv_lifetime.
Example 10. Set restart_fr_on_each_reply
parameter
...
modparam("tm", "restart_fr_on_each_reply", 0)
...
If set (default) tm will automatically send and 100 reply to INVITEs.
Setting it to 0 one can be used to enable doing first some tests or
pre-processing on the INVITE and only if some conditions are met
manually send a 100 (using t_reply()). Note
however that in this case all the 100s have to be sent "by hand".
t_set_auto_inv_100() might help to selectively
turn off this feature only for some specific transactions.
Default value is 1 (on).
See also: t_set_auto_inv_100()
auto_inv_100_reason.
Set reason text of the automatically send 100 to an INVITE.
Default value is "trying -- your call is important to us".
See also: auto_inv_100.
Example 12. Set auto_inv_100_reason parameter
...
modparam("tm", "auto_inv_100_reason", "Trying")
...
Unix socket transmission timeout, in milliseconds.
If unix sockets are used (e.g.: to communicate with sems) and sending
a message on a unix socket takes longer then
unix_tx_timeout, the send will fail.
The default value is 500 milliseconds.
If set (default), the final reply is a 401 or a 407 and more then one branch received a 401 or 407, then all the WWW-Authenticate and Proxy-Authenticate headers from all the 401 and 407 replies will be aggregated in a new final reply. If only one branch received the winning 401 or 407 then this reply will be forwarded (no new one will be built). If 0 only the first 401, or if no 401 was received the first 407, will be forwarded (no header aggregation).
Default value is 1 (required by rfc3261).
If set (default), the CANCEL and negative ACK requests are constructed from the INVITE message which was sent out instead of building them from the received request. The disadvantage is that the outgoing INVITE has to be partially re-parsed, the advantage is that the CANCEL/ACK is always RFC 3261-compliant, it always contains the same route-set as the INVITE message. Do not disable the INVITE re-parsing for example in the following cases:
- The INVITE contains a preloaded route-set, and SER forwards
the message to the next hop according to the Route header. The
Route header is not removed in the CANCEL without
reparse_invite=1.
- SER record-routes, thus an in-dialog INVITE contains a Route
header which is removed during loose routing. If the in-dialog
INVITE is rejected, the negative ACK still contains the Route
header without reparse_invite=1.
Default value is 1.
Header fields prefixed by this parameter value are included in the CANCEL and negative ACK messages if they were present in the outgoing INVITE.
Note, that the parameter value effects only those headers
which are not covered by RFC-3261 (which are neither mandatory
nor prohibited in CANCEL and ACK), and the parameter can be used
only together with reparse_invite=1.
Default value is "".
Example 16. Set ac_extra_hdrs parameter
...
modparam("tm", "ac_extra_hdrs", "myfavoriteheaders-")
...
If set and the blacklist support is enabled, every 503 reply source is
added to the blacklist. The initial blacklist timeout (or ttl) depends
on the presence of a Retry-After header in the reply and the values of
the following tm parameters: blst_503_def_timeout,
blst_503_min_timeout and
blst_503_max_timeout.
WARNING:blindly allowing 503 blacklisting could be very easily exploited for DOS attacks in most network setups.
The default value is 0 (disabled due to the reasons above).
Blacklist interval in seconds for a 503 reply with no Retry-After
header.
See also blst_503,
blst_503_min_timeout and
blst_503_max_timeout.
The default value is 0, which means that if no Retry-After header is present, the 503 reply source will not be blacklisted (rfc conformant behaviour).
Minimum blacklist interval in seconds for a 503 reply with a
Retry-After header. It will be used if the Retry-After value is
smaller.
See also blst_503,
blst_503_def_timeout and
blst_503_max_timeout.
The default value is 0
Maximum blacklist interval in seconds for a 503 reply with a
Retry-After header. It will be used if the Retry-After value is
greater.
See also blst_503,
blst_503_def_timeout and
blst_503_min_timeout.
The default value is 3600
Example 20. Set blst_503_max_timeout parameter
...
modparam("tm", "blst_503_max_timeout", 604800)
...
Bitmap of method types that trigger blacklisting on transaction timeouts. (This setting has no effect on blacklisting because of send failures.)
The following values are associated to the request methods: INVITE=1, CANCEL=2, ACK=4 (not retransmitted, thus, never times-out), BYE=8, INFO=16, REGISTER=32, SUBSCRIBE=64, NOTIFY=126, OTHER=256 (all the unknown types). Check parser/msg_parser.h for farther details.
Change the value carefully, because requests not having provisional response (everything but INVITE) can easily cause the next hop to be inserted into the blacklist by mistake. For exmaple the next hop is a proxy, it is alive, but waiting for the response of the UAS, and has higher fr_timer value.
The default value is 1, only INVITEs trigger blacklisting
Example 21. Set blst_methods_add parameter
...
# INVITEs and REGISTERs trigger blacklisting
modparam("tm", "blst_methods_add", 33)
...
Bitmap of method types that are looked-up in the blacklist
before statefull forwarding.
See also blst_methods_add
The default value is 4294967287, every method type except BYE. (We try to deliver BYEs no matter what)
Example 22. Set blst_methods_lookup parameter
...
# lookup only INVITEs
modparam("tm", "blst_methods_lookup", 1)
...
Method used when attempting to CANCEL an unreplied transaction branch (a branch where no reply greater the 99 was received). The possible values are 0, 1, and 2.
0 will immediately stop the request (INVITE) retransmission on the branch and it will behave as if the branch was immediately replied with a 487 (a fake internal 487 reply). The advantage is the unreplied branches will be terminated immediately. However it introduces a race risk with a possible slightly delayed 2xx reply. In this case we could have an UA receiving a 2xx after a 487. Moreover this risk is greatly amplified by packet loss (e.g. if an 180 is lost the branch will look as unreplied and a CANCEL will silently drop the branch, but a 2xx can still come at a later time). This is the behaviour for ser versions older then 2.1.
1 will keep retransmitting the request on
unreplied branches. If a provisional answer is later received a CANCEL
will be immediately sent back (attempting to quickly trigger a 487).
This approach is race free and avoids the 2xx after 487 problem, but
it's more resource intensive: faced with a branch towards and UA that
doesn't answer, a CANCEL attempt will keep the transaction alive for
the whole timeout interval (fr_timer).
2 will send and retransmit CANCEL even on unreplied branches, stopping the request retransmissions. This has the same advantages as 1 and also avoids the extra roundtrip in the case of the provisional reply, but it's not RFC 3261 conforming (the RFC allows sending CANCELs only on pending branches).
The default value is 1.
If set to 1, the SIP message after a DNS failover is constructed from the outgoing message buffer of the failed branch instead of from the received request.
It must be set if multiple branches are installed, the SIP message is modified differently in them, and at least one of them can result in DNS failover. If the parameter is not set the per-branch modifications are lost after the failover.
Note: If the parameter is set, branch route block and TMCB_REQUEST_FWDED callback are not called in case of the failover.
Disadvantage: only the via header is replaced in the message buffer, so the outgoing socket address is not corrected in any other part of the message. It is dangerous on multihomed hosts: when the new SIP request after the DNS failover is sent via different interface than the first request, the message can contain incorrect ip address in the Record-Route header for instance.
Default value is 1.
Example 24. Set reparse_on_dns_failover parameter
...
modparam("tm", "reparse_on_dns_failover", 0)
...
Sets reply route block, to which control is passed when a reply is received that has no associated transaction. The reply is passed to the core for stateless forwarding after the route block execution unless it returns 0.
Example 25. Set on_sl_reply parameter
...
modparam("tm", "on_sl_reply", "stateless_replies")
...
onreply_route["stateless_replies"] {
# do not allow stateless replies to be forwarded
return 0;
}
This is the name or Id of an AVP
that t_load_contacts() function uses to
store contacts of the destination set and that
t_next_contacts() function uses to
restore those contacts.
Default value is "NULL" (t_load_contacts()/t_next_contacts() functions are disabled).
The value of fr_timer timer can be overriden on per-transaction
basis. The administrator can provide a value to be used for a
particular transaction in an AVP. This parameter contains the name
of the AVP that will be checked. If the AVP exists then its value
will be used for the fr_timer timer, effectively overriding the
value configured in fr_timer parameter for the
current transaction.
The value of this parameter is the the name of the AVP to be checked, without the $ character or "$avp" prefix.
The value of the AVP is expected to be expressed in seconds and not milliseconds (unlike the rest of the timers).
This parameter is kept for backwards compatibility (hence its
value expressed in seconds instead of milliseconds and its arcane
way of specifying the avps). The recommended replacement is using
t_set_fr() on a per transaction basis.
See also: t_set_fr(),
fr_timer.
In Kamailio compatibility mode (defined by #!KAMAILIO), the value of the parameter must be the name of an AVP in pseudo-variable format: $avp(name). In SER compatibility mode it must by just AVP name.
Example 27. Set fr_timer_avp parameter
...
modparam("tm", "fr_timer_avp", "i:708")
# K mode
modparam("tm", "fr_timer_avp", "$avp(i:708)")
...
The value of fr_inv_timer timer can be overriden on
per-transaction basis. The administrator can provide a value to be
used for a particular transaction in an AVP. This parameter
contains the name of the AVP that will be checked. If the AVP
exists, is non-empty and non-zero then its value will be used
for the fr_inv_timer timer, effectively overriding the value
configured in fr_inv_timer parameter for the
current transaction.
The value of this parameter is the the name of the AVP to be checked, without the $ character or "$avp" prefix.
The value of the AVP is expected to be expressed in seconds and not milliseconds (unlike the rest of the timers).
This parameter is kept for backwards compatibility (hence its
value expressed in seconds instead of milliseconds and its arcane
way of specifying the avps). The recommended replacement is using
t_set_fr() on a per transaction basis.
See also: t_set_fr(),
fr_inv_timer.
In Kamailio compatibility mode (defined by #!KAMAILIO), the value of the parameter must be the name of an AVP in pseudo-variable format: $avp(name). In SER compatibility mode it must by just AVP name.
Example 28. Set fr_inv_timer_avp parameter
...
modparam("tm", "fr_inv_timer_avp", "my_fr_inv_timer")
# K mode
modparam("tm", "fr_inv_timer_avp", "$avp(my_fr_inv_timer)")
...
This parameter selects between forwarding CANCELs that do not match any transaction statefully (0, default value), statelessly (1) or dropping them (2). Note that the statefull forwarding has an additional hidden advantage: tm will be able to recognize INVITEs that arrive after their CANCEL. Note also that this feature could be used to try a memory exhaustion DOS attack against a proxy that authenticates all requests, by continuously flooding the victim with CANCELs to random destinations (since the CANCEL cannot be authenticated, each received bogus CANCEL will create a new transaction that will live by default 30s).
Default value is 0.
If set it will also try to match the request uri when doing pre-3261 transaction matching (the via branch parameter does not contain the 3261 cookie).
The only reason to have it not set is for interoperability with old, broken implementations.
Default value is 1 (on).
Can be set at runtime, e.g.:
$ sercmd cfg.set_now_int tm ruri_matching 0
If set it will also try to match the topmost via when doing pre-3261 transaction matching (the via branch parameter does not contain the 3261 cookie).
The only reason to have it not set is for interoperability with old, broken implementations.
Default value is 1 (on).
Can be set at runtime, e.g.:
$ sercmd cfg.set_now_int tm via1_matching 0
If set, TMCB_LOCAL_REPONSE_OUT tm registered callbacks will be called also for provisional replies.
Default value is 0 (off).
Can be set at runtime, e.g.:
$ sercmd cfg.set_now_int tm pass_provisional_replies 1
Example 32. Set pass_provisional_replies parameter
...
modparam("tm", "pass_provisional_replies", 1)
...
Default response code sent by t_reply() if it
cannot retrieve its parameters (e.g. inexistent avp).
Valid values are between 400 and 699.
Default value is 500.
Can be set at runtime, e.g.:
$ sercmd cfg.set_now_int tm default_code 505
Default SIP reason phrase sent by t_reply() if it
cannot retrieve its parameters (e.g. inexistent avp).
Default value is "Server Internal Error".
Can be set at runtime, e.g.:
$ sercmd cfg.set_now_string tm default_reason "Unknown error"
If set tm will treat all the 6xx replies like normal replies (warning: this would be non-rfc conformant behaviour).
If not set (default) receiving a 6xx will cancel all the running
parallel branches, will stop dns failover and forking. However
serial forking using append_branch() in the
failure_route will still work.
It can be overwritten on a per transaction basis using
t_set_disable_6xx().
Default value is 0 (off, rfc conformant behaviour).
Can be set at runtime, e.g.:
$ sercmd cfg.set_now_int tm disable_6xx_block 0
See also: t_set_disable_6xx().
It controls where locally generated ACKs for 2xx replies to local
transactions (transactions created via t_uac*()
either thorugh the tm api or via RPC/mi/fifo) are sent.
It has 3 possible values:
0 - the ACK destination is choosen according to the rfc: the next hop is found using the contact and the route set and then DNS resolution is used on it.
1 - the ACK is sent to the same address as the corresponding INVITE branch.
2 - the ACK is sent to the source of the 2xx reply.
Mode 1 and 2 break the rfc, but are useful to deal with some simple UAs behind the NAT cases (no different routing for the ACK and the contact contains an address behind the NAT).
The default value is 0 (rfc conformant behaviour).
Can be set at runtime, e.g.:
$ sercmd cfg.set_now_int tm local_ack_mode 0
It controls how branches are managed and replies are selected for failure_route handling: keep all, drop all, drop last branches in SIP serial forking handling.
To control per transaction see t_drop_replies().
It has 4 possible values:
0 - all branches are kept, no matter a new leg of serial forking has been started. Beware that if the new leg fails, you may get in failure_route a reply code from a branch of previous serial forking legs (e.g., if in first leg you got a 3xx, then you handled the redirection in failure route, sent to a new destination and this one timeout, you will get again the 3xx). Use t_drop_replies() on per transaction fashion to control the behavior you want. It is the default behaviour comming from SER 2.1.x.
1 - all branches are discarded by default. You can still overwrite the behaviour via t_drop_replies()
2 - by default only the branches of previous leg of serial forking are discarded
3 - all previous branches are discarded if there is a new serial forking leg. This is the default behaviour coming from Kamailio 1.5.x. Use this mode if you don't want to handle in a per transaction fashion with t_drop_replies(). It ensures that you will get the winning reply from the branches of last serial forking step (e.g., if in first step you get 3xx, then you forward to a new destination, you will get in failure_route the reply coming from that destination or a local timeout).
The default value is 0.
It controls how branch selection is done. It allows to give a penalty to faked replies such as the infamous 408 on branch timeout.
Internally, every reply is assigned a priority between 0 (high prio) and 32000 (low prio). With this parameter the priority of fake replies can be adjusted.
0 - disabled (default)
< 0 - priority is increased by given amount.
> 0 - priority is decreased by given amount. Do not make it higer than 10000 or faked replies will even loose from 1xx clsss replies.
The default value is 0.
To let received replies win from a locally generated 408, set this value to 2000.
Enables/disables adding reason headers (RFC 3326) for CANCELs generated due to receiving a final reply. The reason header added will look like: "Reason: SIP;cause=<final_reply_code>".
Default value is 1 (enabled).
Can be set at runtime, e.g.:
$ sercmd cfg.set_now_int tm local_cancel_reason 0
See also: e2e_cancel_reason.
Enables/disables adding reason headers (RFC 3326) for CANCELs generated due to a received CANCEL. If enabled the reason headers from received CANCELs will be copied into the generated hop-by-hop CANCELs.
Default value is 1 (enabled).
Can be changed at runtime, e.g.:
$ sercmd cfg.set_now_int tm e2e_cancel_reason 0
See also: t_set_no_e2e_cancel_reason() and
local_cancel_reason.
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.
t_relay() is the statefull version for
forward()
while t_relay(host, port) is similar to
forward(host, port).
In the forward to uri case (t_relay()), 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).
Returns a negative value on failure -- you may still want to send a negative reply upstream statelessly not to leave upstream UAC in lurch.
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
t_relay are the functions most users want to
use--all other are mostly for programming. Programmers interested
in writing TM logic should review how t_relay is
implemented in tm.c and how TM callbacks work.
Meaning of the parameters is as follows:
ip - IP address where the message should be sent.
port - Port number.
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.
Example 42. t_relay_to_udp usage
...
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
...
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 (t_reply). 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.
Meaning of the parameters is as follows:
failure_route - Failure route block to be called.
Example 43. t_on_failure usage
...
route {
t_on_failure("1");
t_relay();
}
failure_route[1] {
revert_uri();
setuser("voicemail");
append_branch();
}
...
See test/onr.cfg for a more complex example of
combination of serial with parallel forking.
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.
Meaning of the parameters is as follows:
onreply_route - Onreply route block to be called.
Example 44. t_on_reply usage
...
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();
}
}
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.
Meaning of the parameters is as follows:
branch_route - branch route block to be called.
Example 45. t_on_branch usage
...
route {
t_on_branch("1");
t_relay();
}
branch_route[1] {
if (uri=~"sip:[0-9]+"){
append_hf("P-Warn: numeric uri\r\n");
}
}
Similarly to t_fork_to, it extends destination
set by a new entry. The difference is that current URI is taken
as new entry.
Example 46. append_branch usage
...
set_user("john");
t_fork();
set_user("alice");
t_fork();
t_relay();
...
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.
Example 47. t_newtran usage
...
if (t_newtran()) {
log("UAS logic");
t_reply("999","hello");
} else sl_reply_error();
...
See test/uas.cfg for more examples.
Sends a stateful reply after a transaction has been
established. See t_newtran for usage.
Meaning of the parameters is as follows:
code - Reply code number.
reason_phrase - Reason string.
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
t_newtran.
Retransmits a reply sent previously by UAS transaction.
Remove transaction from memory (it will be first put on a wait timer to absorb delayed messages).
Mainly for internal usage -- forward a non-ACK request statefully. Variants of this functions can enforce a specific transport protocol.
Meaning of the parameters is as follows:
ip - IP address where the message should be sent.
port - Port number.
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
t_relay() 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.
Meaning of the parameters is as follows:
fr_inv_timeout - new final response timeout
(in milliseconds) for INVITEs. See also
fr_inv_timer.
fr_timeout - new final response timeout
(in milliseconds) for non-INVITE transaction, or INVITEs which
haven't received yet a provisional response. See also
fr_timer.
See also:
fr_timer,
fr_inv_timer,
t_reset_fr().
Example 53. t_set_fr usage
...
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);
}
}
Resets the fr_inv_timer and
fr_timer for the current transaction to the default
values (set using the tm module parameters
fr_inv_timer and fr_timer).
It will effectively cancel any previous calls to
t_set_fr for the same transaction.
See also: fr_timer,
fr_inv_timer,
t_set_fr.
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.
It works as a per transaction max_inv_lifetime or
max_noninv_lifetime.
Meaning of the parameters is as follows:
inv_lifetime - maximum INVITE transaction
lifetime (in milliseconds). See also
max_inv_lifetime.
noninv_lifetime - maximum non-INVITE
transaction lifetime (in milliseconds).
See also max_noninv_lifetime.
See also: max_inv_lifetime,
max_noninv_lifetime,
t_reset_max_lifetime.
Example 55. t_set_max_lifetime usage
...
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
}
Resets the the maximum lifetime for the current INVITE or non-INVITE
transaction to the default value (set using the tm module parameter
max_inv_lifetime or
max_noninv_lifetime).
It will effectively cancel any previous calls to
t_set_max_lifetime for the same transaction.
See also: max_inv_lifetime,
max_noninv_lifetime,
t_set_max_lifetime.
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
t_relay() 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).
Meaning of the parameters is as follows:
retr_t1_interval - new T1 retransmission
interval (in milliseconds). See also
retr_t1_timeout.
retr_t2_interval - new T2 (or maximum)
retransmission interval (in milliseconds). See also
retr_t2_timeout.
See also:
retr_timer1,
retr_timer2,
t_reset_retr().
Example 57. t_set_retr usage
...
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);
}
}
Resets the retr_timer1 and
retr_timer2 for the current transaction to the
default values (set using the tm module parameters
retr_timer1 and retr_timer2).
It will effectively cancel any previous calls to
t_set_retr for the same transaction.
See also: retr_timer1,
retr_timer2,
t_set_retr.
Switch automatically sending 100 replies to INVITEs on/off on a
per transaction basis. It overrides the
auto_inv_100 value for the current transaction.
See also: auto_inv_100.
Example 59. t_set_auto_inv_100 usage
...
route {
...
if (src_ip==1.2.3.0/24)
t_set_auto_inv_100(0); # turn off automatic 100 replies
...
}
Returns true if the failure route is executed for a branch that did timeout. It can be used only from the failure_route.
Example 60. t_branch_timeout usage
...
failure_route[0]{
if (t_branch_timeout()){
log("timeout\n");
# ...
}
}
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 failure_route.
Example 61. t_branch_replied usage
...
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");
# ...
}
}
Returns true if at least one of the current transactions branches did timeout.
Example 62. t_any_timeout usage
...
failure_route[0]{
if (!t_branch_timeout()){
if (t_any_timeout()){
log("one branch did timeout\n");
sl_send_reply("408", "Timeout");
}
}
}
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.
Example 63. t_any_replied usage
...
onreply_route[0]{
if (!t_any_replied()){
log("first reply received\n");
# ...
}
}
Returns true if "code" is the final reply received (or locally generated) in at least one of the current transactions branches.
Example 64. t_grep_status usage
...
onreply_route[0]{
if (t_grep_status("486")){
/* force a 486 reply, even if this is not the winning branch */
t_reply("486", "Busy");
}
}
Returns true if the current transaction was canceled.
Example 65. t_is_canceled usage
...
failure_route[0]{
if (t_is_canceled()){
log("transaction canceled\n");
# ...
}
}
Returns true if the current transaction has already been expired, i.e. the max_inv_lifetime/max_noninv_lifetime interval has already elapsed.
Example 66. t_is_expired usage
...
failure_route[0]{
if (t_is_expired()){
log("transaction expired\n");
# There is no point in adding a new branch.
}
}
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
reparse_invite module parameter, and call
t_relay_cancel() right after the sanity tests.
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.
Example 67. t_relay_cancel usage
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
}
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
t_relay_cancel includes
t_lookup_cancel as well, therefore it is not
needed to explicitly call this function unless something has to be
logged for example.
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.
Example 68. t_lookup_cancel usage
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
}
Drops all the previously received replies in failure_route block to make sure that none of them is picked up again.
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.
Dropping replies works only if a new branch is added to the transaction, or it is explicitly replied in the script!
Example 69. t_drop_replies() usage
...
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();
}
}
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.
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.
The transaction must be created by t_newtran() before calling t_save_lumps().
Example 70. t_save_lumps() usage
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();
}
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.
The function t_load_contacts() takes all
branches from the current destination set and encodes them into the
AVP whose name or ID is configured with the
parameter contacts_avp. 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.
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 t_relay(), so there is no need
to create the AVP or sort the branches.
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.
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.
After that the function clears all branches and you have to
call t_next_contacts to retrieve them sorted
according to their q value. Note that if you
use t_load_contacts then you also have to
use t_next_contacts before
calling t_relay.
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.
The function returns 1 if loading of contacts succeeded or there was nothing to do. Returns -1 on error (see syslog).
This function can be used from REQUEST_ROUTE.
Example 71. t_load_contacts usage
...
if (!t_load_contacts()) {
sl_send_reply("500", "Server Internal Error - Cannot load contacts");
exit;
};
...
The function t_next_contacts 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.
This function takes the contact_avp created
by t_load_contacts 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.
The function does nothing if there are
no contact_avp values.
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.
Note that if use use t_load_contacts
and t_next_contacts functions then you should
also set the value of restart_fr_on_each_reply
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.
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.
Example 72. t_next_contacts usage
...
# 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();
};
...
t_check_trans() can be used to quickly check if
a message belongs or is related to a transaction. It behaves
differently for different types of messages:
For a SIP Reply it returns true if the reply belongs to an existing transaction and false otherwise.
For a CANCEL it behaves exactly as
t_lookup_cancel(): returns true if a
corresponding INVITE transaction exists for the CANCEL and
false otherwise.
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.
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.
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).
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).
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.
t_check_trans() functionality for requests,
except for the e2e ACK matching, can be replicated in the script
using t_lookup_cancel() and
t_lookup_request().
See also: t_lookup_request(),
t_lookup_cancel().
Example 73. t_check_trans usage
if ( method == "CANCEL" && !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()
Turn off/on 6xx replies special rfc conformant handling on a per
transaction basis. If turned off
(t_set_disable_6xx("1")) 6XXs will be treated
like normal replies.
It overrides the disable_6xx_block value for
the current transaction.
See also: disable_6xx_block.
Example 74. t_set_disable_6xx usage
...
route {
...
if (src_ip==1.2.3.4) # bad user agent that sends 603
t_set_disable_6xx(1); # turn off 6xx special handling
...
}
Turn off/on dns failover on a per transaction basis.
See also: use_dns_failover.
Example 75. t_set_disable_failover usage
...
route {
...
if (uri=~"@foo.bar$")
t_set_disable_failover(1); # turn off dns failover
...
}
Replicate the SIP request to a specific address.
There are several function prototypes:
t_replicate(uri),
t_replicate(host, port),
t_replicat_udp(host, port)
t_replicate_tcp(host, port)
t_replicate_tls(host, port)
t_replicate_sctp(host, port)
t_replicate_to(proto, hostport)
Meaning of the parameters is as follows:
uri - SIP URI where the message should be sent. It can be given via a script variable.
host - host address where the message should be sent.
port - port number.
proto - transport protocol to be used.
hostport - address in "host:port" format. It can be given via an AVP.
Example 76. t_replicate usage
...
# 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");
...
Forward the SIP request to a specific address, controlling internal behavior via flags.
There are several function prototypes:
t_relay_to(),
t_relay_to(proxy),
t_relay_to(flags)
t_relay_to(proxy, flags)
Meaning of the parameters is as follows:
proxy - 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.
flags - bitmask integer value to control the internal behavior. Bits can be:
0x01 - do not generate 100 reply.
0x02 - do not generate reply on internal error (NOTE: has no effect anymore).
0x04 - disable dns failover.
Example 77. t_relay_to usage
...
# 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");
...
Enables/disables reason header (RFC 3326) copying from the triggering received CANCEL to the generated hop-by-hop CANCEL. 0 enables and 1 disables.
It overrides the e2e_cancel_reason setting (module
parameter) for the current transaction.
See also: e2e_cancel_reason.
Example 78. t_set_no_e2e_cancel_reason usage
...
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
...
}
There are applications which would like to generate SIP transactions without too big involvement in SIP stack, transaction management, etc. An example of such an application is sending instant messages from a website. To address needs of such apps, SIP-router accepts requests for new transactions via the management interface. If you want to enable this feature, start the management interface server by configuring the proper modules.
An application can easily launch a new transaction by writing a transaction request to this interface. The request must follow very simple format, which for the basic FIFO interface is
:t_uac_from:[<file_name>]\n <method>\n <sender's uri>\n <dst uri>\n <CR_separated_headers>\n <body>\n .\n \n
(Filename is to where a report will be dumped. ser assumes /tmp as file's directory.)
Note the request write must be atomic, otherwise it might get intermixed with writes from other writers. You can easily use it via Unix command-line tools, see the following example:
[jiri@bat jiri]$ cat > /tmp/ser_fifo :t_uac_from:xxx MESSAGE sip:sender@iptel.org sip:mrx@iptel.org header:value foo:bar bznk:hjhjk p_header: p_value body body body yet body end of body .
or cat test/transaction.fifo > /tmp/ser_fifo
ACK_TAG enables stricter matching of acknowledgments including to-tags. Without it, to-tags are ignored. It is disabled by default for two reasons:
It eliminates an unlikely race condition in which transaction's to-tag is being rewritten by a 200 OK whereas an ACK is being looked up by to-tag.
It makes UACs happy who set wrong to-tags.
It should not make a difference, as there may be only one negative reply sent upstream and 200/ACKs are not matched as they constitute another transaction. It will make no difference at all when the new magic cookie matching is enabled anyway.
CANCEL_TAG similarly enables strict matching of CANCELs including to-tags--act of mercy to UACs, who screw up the to-tags (however, it still depends on how forgiving the downstream UAS is). Like with ACK_TAG, all this complex transactions matching goes with RFC3261's magic cookie away anyway.
For programmatic use only--register a function to be called back on an event. See t_hooks.h for more details.
Meaning of the parameters is as follows:
cb_type - Callback type.
cb_func - Callback function.
For programmatic use only--import exported TM functions. See the acc module for an example of use.
Meaning of the parameters is as follows:
import_structure - Pointer to the import structure.
For programmatic use only. This function together with t_continue() can be used to implement asynchronous actions: t_suspend() saves the transaction, returns its identifiers, and t_continue() continues the SIP request processing. (The request processing does not continue from the same point in the script, a separate route block defined by the parameter of t_continue() is executed instead. The reply lock is held during the route block execution.) FR timer is ticking while the transaction is suspended, and the transaction's failure route is executed if t_continue() is not called in time.
Missing: message lumps are saved by t_suspend() and are not updated by the subsequent t_relay(). This means that the modifications made between them are lost.
Meaning of the parameters is as follows:
msg - SIP message pointer.
hash_index - transaction identifier.
label - transaction identifier.
Return value: 0 - success, <0 - error.
Usage: Allocate a memory block for storing the transaction identifiers (hash_index and label), and for storing also any variable related to the async query. Before calling t_suspend(), register for the following callbacks, and pass the pointer to the allocated shared memory as a parameter: TMCB_ON_FAILURE, TMCB_DESTROY, and TMCB_E2ECANCEL_IN (in case of INVITE transaction). The async operation can be cancelled, if it is still pending, when TMCB_ON_FAILURE or TMCB_E2ECANCEL_IN is called. TMCB_DESTROY is suitable to free the shared memory allocated for the async and SIP transaction identifiers. Once the async query result is available call t_continue(), see below. The SIP transaction must exist before calling t_suspend(), and the module function calling t_suspend() should return 0 to make sure that the script processing does not continue.
For programmatic use only. This function is the pair of t_suspend(), and is supposed to be called when the asynchronous query result is available. The function executes a route block with the saved SIP message. It is possible to add more branches to the transaction, or send a reply from the route block.
Meaning of the parameters is as follows:
hash_index - transaction identifier.
label - transaction identifier.
route - route block to execute.
Return value: 0 - success, <0 - error.
For programmatic use only. This function is for revoking t_suspend() from the same process as it was executed before. t_cancel_suspend() can be used when something fails after t_suspend() has already been executed and it turns out that the transcation should not have been suspended. The function cancels the FR timer of the transacation.
The message lumps are saved by t_suspend() which cannot be restored.
Meaning of the parameters is as follows:
hash_index - transaction identifier.
label - transaction identifier.
Return value: 0 - success, <0 - error.