---
title: "UAC REDIRECT Module"
description: "UAC REDIRECT - User Agent Client redirection - module enhance OpenSIPS with the functionality of being able to handle (interpret, filter, log and follow) redirect responses ( 3xx replies class)."
---

## Admin Guide


### Overview


UAC REDIRECT - User Agent Client redirection - module enhance OpenSIPS
with the functionality of being able to handle (interpret, filter,
log and follow) redirect responses ( 3xx replies class).


UAC REDIRECT module offer stateful processing, gathering the
contacts from all 3xx branches of a call.


The module provide a powerful mechanism for selecting and filtering 
the contacts to be used for the new redirect:


- *number based* - limits like the 
number of total contacts to be used or the maximum number of 
contacts per branch to be selected.
- *Regular Expression based* - combinations
of deny and accept filters allow a strict control of the 
contacts to be used for redirection.


When selecting from a 3xx branch the contacts to be used, the contacts
will be ordered and prioritized based on the "q" value.


### Dependencies


#### OpenSIPS Modules


The following modules must be loaded before this module:


- *TM* - Transaction Module, for accessing
replies.
- *ACC* - Accounting Module, but only if the
logging feature is used.


#### External Libraries or Applications


The following libraries or applications must be installed 
before running OpenSIPS with this module loaded:


- *None*


### Exported Parameters


#### default_filter (string)


The default behavior in filtering contacts. It may be 
"accept" or "deny".


*The default value is "accept".*


```opensips title="Set default_filter module parameter"
...
modparam("uac_redirect","default_filter","deny")
...
				
```


#### deny_filter (string)


The regular expression for default deny filtering. It make sens
to be defined on only if the `default_filter`
parameter is set to "accept". All contacts matching
the `deny_filter` will be rejected; the rest 
of them will be accepted for redirection.


The parameter may be defined only one - multiple definition will
overwrite the previous definitions. If more regular expression 
need to be defined, use the 
`set_deny_filter()` scripting
function.


*This parameter is optional, it's default 
value being NULL.*


```opensips title="Set deny_filter module parameter"
...
modparam("uac_redirect","deny_filter",".*@siphub\.net")
...
				
```


#### accept_filter (string)


The regular expression for default accept filtering. It make sens
to be defined on only if the `default_filter`
parameter is set to "deny". All contacts matching
the `accept_filter` will be accepted; the rest 
of them will be rejected for redirection.


The parameter may be defined only one - multiple definition will
overwrite the previous definitions. If more regular expression 
need to be defined, use the 
`set_accept_filter()` scripting
function.


*This parameter is optional, it's default 
value being NULL.*


```opensips title="Set accept_filter module parameter"
...
modparam("uac_redirect","accept_filter",".*@siphub\.net")
...
				
```


### Exported Functions


#### set_deny_filter(filter,flags)


Sets additional deny filters. Maximum 6 may be combined. This
additional filter will apply only to the current message - it
will not have a global effect.


Parameters:


- *filter* (string) - regular expression
- *flags* (string)
Default or previous added deny filter may be reset depending of
the parameter value:

  - *reset_all* - reset both default
and previous added deny filters;
  - *reset_default* - reset only the
default deny filter;
  - *reset_added* - reset only the 
previous added deny filters;
  - *empty* - no reset, just add the
filter.


This function can be used from FAILURE_ROUTE.


```opensips title="set_deny_filter usage"
...
set_deny_filter(".*@domain2.net","reset_all");
set_deny_filter(".*@domain1.net","");
...
				
```


#### set_accept_filter(filter,flags)


Sets additional accept filters. Maximum 6 may be combined. This
additional filter will apply only to the current message - it
will not have a global effect.


Parameters:


- *filter* (string) - regular expression
- *flags* (string)
Default or previous added deny filter may be reset depending of
the parameter value:

  - *reset_all* - reset both default
and previous added accept filters;
  - *reset_default* - reset only the
default accept filter;
  - *reset_added* - reset only the 
previous added accept filters;
  - *empty* - no reset, just add
the filter.


This function can be used from FAILURE_ROUTE.


```opensips title="set_accept_filter usage"
...
set_accept_filter(".*@domain2.net","reset_added");
set_accept_filter(".*@domain1.net","");
...
				
```


#### get_redirects([max_total], [max_branch])


The function may be called only from failure routes. It will
extract the contacts from all 3xx branches and append them
as new branches. Note that the function will not forward the
new branches, this must be done explicitly from script.


How many contacts (in total and per branch) are selected 
depends on the *max_total* and
*max_branch* parameters:


- max_total (int, optional) - max overall number of contacts to be selected
- max_branch (int, optional) - max number of contacts per branch to be selected


Both "max_total" and "max_branch"
default to 0 (unlimited).


> [!NOTE]
> During the selection process, each set of contacts 
> from a specific branch are ordered based on "q" 
> value.


This function can be used from FAILURE_ROUTE.


```opensips title="get_redirects usage"
...
# no restrictions
get_redirects();
...
# no limits per branch, but not more than 6 overall contacts
get_redirects(6);
...
# max 2 contacts per branch, but no overall limit
get_redirects(, 2);
...
				
```


### Script Example


```opensips title="Redirection script example"
loadmodule "modules/sl/sl.so"
loadmodule "modules/usrloc/usrloc.so"
loadmodule "modules/registrar/registrar.so"
loadmodule "modules/tm/tm.so"
loadmodule "modules/acc/acc.so"
loadmodule "modules/uac_redirect/uac_redirect.so"

modparam("usrloc", "working_mode_preset", "single-instance-no-db")

route{
	if (is_myself("$rd")) {

		if ($rm=="REGISTER") {
			save("location");
			exit;
		};

		if (!lookup("location")) {
			sl_send_reply(404, "Not Found");
			exit;
		};
	}

	t_on_failure("do_redirect");

	if (!t_relay()) {
		sl_reply_error();
	};
}

failure_route[do_redirect] {
	if (get_redirects(3, 1))
		t_relay();
}

				
```
<!-- CONTRIBUTORS -->

### License

All documentation files (i.e. .md extension) are licensed under the Creative Common License 4.0
