---
title: "registrar Module"
description: "The module contains SIP REGISTER request processing logic, per RFC 3261."
---

## Admin Guide


### Overview


The module contains SIP REGISTER request processing logic, per RFC
	3261.  On top of this support, several extensions are available:


#### Path Support (RFC 3327)


The registrar module includes SIP Path header field support
according to
[RFC 3327](https://tools.ietf.org/html/rfc3327),
for usage in registrars and home-proxies.


A call to *save()* stores, if path support is enabled
in the registrar module, the values of the Path
Header(s) along with the Contact information into usrloc. There are
three modes for building the reply to a REGISTER message which
includes one or more Path header fields:


- *off* - stores the value of the
Path headers into usrloc without passing it back to
the UAC in the reply.
- *lazy* - stores the Path header and
passes it back to the UAC if Path-support is indicated
by the "path" param in the Supported HF.
- *strict* - rejects the registration
with "420 Bad Extension" if there's a Path
header but no support for it is indicated by the UAC.
Otherwise it's stored and passed back to the UAC.


A call to *lookup()* always uses the Path header if
found, and inserts it as Route HF either in front of
the first Route HF, or after the last Via HF if no
Route is present. It also sets the destination URI to
the first Path URI, thus overwriting the received-URI,
because NAT has to be handled at the outbound-proxy of
the UAC (the first hop after client's NAT).


The whole process is transparent to the user, so no
config changes are required besides enabling one of the
"p0" / "p1" / "p2" flags when calling *save()*.


#### GRUU Support (RFC 5627)


The registrar module includes support for Globally Routable User
Agent URIs according to [RFC 5627](https://tools.ietf.org/html/rfc5627).


A call to *save()* stores, if the phone supports GRUU,
the values of the SIP Instance along with the contact into usrloc.
The module will generate two types of GRUUs:


- *public* - exposes the underlying AOR,
constructed just by attaching the SIP Instance as the ;gr
parameter value. These are persistent, valid as long as the
contact registration is valid.
- *temporary* - hides the underlying AOR
Each new Register request leads to the construction of a
new temporary GRUU, while Register requests with a different
Call-ID lead to the invalidation of all the previous generated
temporary GRUUs.


A call to *lookup()* will try to detect if the R-URI contains a
GRUU.  If it does, it will route the request just for the Contact
that the specific AOR belongs to, without appending any other branches.


Even if the the GRUU handling during the registration process is
transparent to the user, so no config changes are required, you need
to take care of the GRUU specifics when handling mid-dialog requests.


As the GRUU will be present in the contact header of the initial
requests generated byt GRUU enabled devices, you will have to also
do a lookup() when receiving a mid-dialog request with the GRUU
indication in the RURI.


#### SIP Push Notification Support (RFC 8599)


The registrar module includes support for standards-based SIP Push
Notifications, per
[RFC 8599](https://tools.ietf.org/html/rfc8599).
Support for the basic version of the draft can be enabled by switching
[pn enable](#pn_enable-boolean) to *true*.  The
module also includes optional support for sending Push Notifications
during long-lived dialogs ([see RFC section 6](https://tools.ietf.org/html/rfc8599#page-23)),
through the [pn enable purr](#pn_enable_purr-boolean) switch.


Essential mechanics behind the Push Notification (PN) support:


- the PN support is fully compatible with the existing logic and
enabling it does not impose any limitations, as the
registrar can simultaneously handle both SIP PN compliant
and standard SIP User Agents
- OpenSIPS will raise a
[E_UL_CONTACT_REFRESH](../usrloc/README.md#e_ul_contact_refresh)
event any time a Push Notification needs to be sent to a
PN-enabled contact.  The event includes the PN coordinates of
the contact -- they may be found in the Contact URI ('uri'
event parameter) and may be extracted using the {uri.param,name}
transformation. From here onwards, it is up to the script
developer to trigger the Push Notification (e.g. possibly by
sending an HTTP POST with the
[rest_client](../rest_client/README.md) module), thus forcing
a re-registration from the device.
- REGISTER processing is unchanged -- PN-enabled UAs are saved
just as regular UAs, with the former ones additionally having
the *4* bitflag set in the "Flags" field of
any MI listing of contacts, for differentiation purposes
- initial INVITE processing is barely changed, with the *lookup()*
function now additionally returning a value of
**2** if the only
found contacts were PN-enabled contacts, all which required a
Push Notification.  This means that PNs have been triggered for
each of them and t_relay() is not required, since they are not
reachable until they re-register!
Using the event_routing module, OpenSIPS will transparently
fork a new branch from the current INVITE on each
re-registration from these contacts within the accepted
[pn refresh timeout](#pn_refresh_timeout-integer)
- mid-dialog requests: In some cases (e.g. long-lived dialogs),
a PN may be required before being able to route a mid-dialog
request to a SIP UA.  The [afunc pn process purr](#pn_process_purrdomain)
async function will take care of triggering the PN event and
resuming the script as soon as a re-registration from the
concerned contact is received.


For more information or examples, refer to the documentation of the
"pn_xxx" module parameters or the OpenSIPS blog posts around the
"SIP Push Notification" topic.


### Dependencies


#### OpenSIPS Modules


The following modules must be loaded before this module:


- *usrloc - User Location Module*.
- *signaling - Signaling module*.
- *event_routing*,
if [pn enable](#pn_enable-boolean) is set to *true*.


#### External Libraries or Applications


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


- *None*.


### Exported Parameters


#### default_expires (integer)


If the processed message contains neither Expires
HFs nor expires contact parameters, this value
will be used for newly created usrloc records. The parameter contains
number of second to expire (for example use 3600 for one hour).


*Default value is 3600.*


```opensips title="Set default_expires parameter"
...
modparam("registrar", "default_expires", 1800)
...
```


#### min_expires (integer)


The minimum expires value of a Contact, values lower than this
minimum will be automatically set to the minimum. Value 0 disables
the checking.


*Default value is 60.*


```opensips title="Set min_expires parameter"
...
modparam("registrar", "min_expires", 60)
...
```


#### max_expires (integer)


The maximum expires value of a Contact, values higher than this
maximum will be automatically set to the maximum. Value 0 disables
the checking.


*Default value is 0.*


```opensips title="Set max_expires parameter"
...
modparam("registrar", "max_expires", 120)
...
```


#### default_q (integer)


The parameter represents default q value for new contacts. Because
OpenSIPS doesn't support float parameter types, the value in the parameter
is divided by 1000 and stored as float. For example, if you want
default_q to be 0.38, use value 380 here.


*Default value is 0.*


```opensips title="Set default_q parameter"
...
modparam("registrar", "default_q", 1000)
...
```


#### tcp_persistent_flag (string)


The parameter specifies the message flag to be used to control the
module behaviour regarding TCP connections. If the flag is set for a
REGISTER via TCP containing a TCP contact, the module, via the
"save()" function, will set the lifetime of the TCP
connection to the contact expire value. By doing this, the TCP
connection will stay on as long as the contact is valid.


*Default value is -1 (disabled).*


```opensips title="Set tcp_persistent_flag parameter"
...
modparam("registrar", "tcp_persistent_flag", "TCP_PERSIST_DURATION")
...
```


#### realm_prefix (string)


Prefix to be automatically strip from realm. As an alternative to
SRV records (not all SIP clients support SRV lookup), a subdomain of
the master domain can be defined for SIP purposes (like
sip.mydomain.net pointing to same IP address as the SRV record for
mydomain.net). By ignoring the realm_prefix "sip.", at registration,
sip.mydomain.net will be equivalent to mydomain.net .


*Default value is NULL (none).*


```opensips title="Set realm_prefix parameter"
...
modparam("registrar", "realm_prefix", "sip.")
...
```


#### case_sensitive (integer)


If set to 1 then AOR comparison will be case
sensitive (as RFC3261 instructs), if set to 0 then
AOR comparison will be case insensitive.


*Default value is 1.*


```opensips title="Set case_sensitive parameter"
...
modparam("registrar", "case_sensitive", 0)
...
```


#### received_avp (str)


Registrar will store the value of the AVP configured by this
parameter in the received column in the user location database.
It will leave the column empty if the AVP is empty. The AVP should
contain a SIP URI consisting of the source IP, port,
and protocol of the REGISTER message being processed.


> [!NOTE]
> The value of this parameter should be the same as the value of
corresponding parameter of nathelper module.


*Default value is "NULL" (disabled).*


```opensips title="Set received_avp parameter"
...
modparam("registrar", "received_avp", "$avp(rcv)")
...
```


#### received_param (string)


The name of the parameter that will be appended to Contacts of
200 OK when the received URI was set by nathelper module.


*Default value is "received".*


```opensips title="Set received_param parameter"
...
modparam("registrar", "received_param", "rcv")
...
```


#### allow_dup_cseq (boolean)


Some SIP stacks will re-REGISTER using the same Call-ID and CSeq values.
While rejecting such requests is consistent with RFC 3261 § 10.3.7, enabling
this parameter instructs the registrar to accept them instead,
improving interoperability.


*Default value is *true* (duplicate CSeq is accepted).*


```opensips title="Setting the allow_dup_cseq parameter"
...
# strict RFC 3261 compliance: reject REGISTER requests with duplicate CSeq
modparam("
```


#### expires_max_deviation (integer)


Set this parameter in order to add a random +/- deviation up to
and including the given value to the expiration interval of a
newly registered contact.  For example, if this parameter is set to
*100* and a phone registers for 1800 sec, the final
expiry will be a random number in the [1700, 1900] interval.
By randomizing the registration lifetimes of the contacts, the
server is better equipped to deal with a post-restart *registration
storm*, when all TCP connections are lost and a significant portion of
UAs will re-register at the same time.  Thanks to the contact lifetime
randomization, the registration storm will only happen once rather
than, e.g., every 1800 seconds following the restart.


*Default value is 0 (no deviation).*


```opensips title="Setting the expires_max_deviation parameter"
...
# add a random +/- 0-100 seconds to each registration lifetime
modparam("
```


#### max_contacts (integer)


The parameter can be used to limit the number of contacts per
AOR (Address of Record) in the user location database. Value 0
disables the check.
This is the default value and will be used only if no other value
(for max_contacts) is passed as parameter to the save() function.
That's it - the function parameter overwride this global parameter.


*Default value is 0.*


```opensips title="Set max_contacts parameter"
...
# Allow no more than 10 contacts per AOR
modparam("
```


#### max_username_len (integer)


The maximum length of the "username" part of an Address-of-Record SIP URI.


Default value is **64**.


```opensips title="Setting the *max_username_len* module parameter"
modparam("
```


#### max_domain_len (integer)


The maximum length of the "domain" part of an Address-of-Record SIP URI.


Default value is **64**.


```opensips title="Setting the *max_domain_len* module parameter"
modparam("
```


#### max_aor_len (integer)


The maximum length of an Address-of-Record SIP URI.


Default value is **256**.


```opensips title="Setting the *max_aor_len* module parameter"
modparam("
```


#### max_contact_len (integer)


The maximum length of a Contact header field SIP URI.


Default value is **255**.


```opensips title="Setting the *max_contact_len* module parameter"
modparam("
```


#### retry_after (integer)


The registrar can generate 5xx reply to REGISTER in various
situations. It can, for example, happen when the
`max_contacts` parameter is set and the
processing of REGISTER request would exceed the limit. In this case
the registrar would generate "503 Service Unavailable" response.


If you want to add the Retry-After header field in 5xx replies, set
this parameter to a value grater than zero (0 means do not add the
header field). See section 20.33 of RFC3261 for more details.


*Default value is 0 (disabled).*


```opensips title="Set retry_after parameter"
...
modparam("registrar", "retry_after", 30)
...
		
```


#### sock_hdr_name (string)


Header which contains a socket description (proto:IP:port) to override
the received socket info. The header will be search and used only if
the flag 's' (Socket header) is set at "save()" time.


This makes sense only in multiple replicated servers scenarios.


*Default value is NULL.*


```opensips title="Set sock_hdr_namer parameter"
...
modparam("registrar", "sock_hdr_name", "Sock-Info")
...
		
```


#### mcontact_avp (string)


AVP to store the modified binding/contact that is set during cached
registrations scenario (when REGISTER is forwarded to another
registrar).  The AVP will be used to extract the "expires" value
returned in the 200 OK by the main registrar.


This makes sense only in cached registrations scenario, where your
OpenSIPS is caching registrations before forwarding them to the main
registrar.


*Default value is NULL.*


```opensips title="Set mcontact_avp parameter"
...
modparam("registrar", "mcontact_avp", "$avp(orig_ct)")
...
route {
   ...
   # before forwarding the REGISTER request, save the outgoing contact.
   # Be SURE to do it after all the possible changes over the contact,
   # like fix_nated_contact()
   $avp(orig_ct) = $ct.fields(uri);
   t_on_reply("do_save");
   t_relay("udp:ip:port");
   ...
}
...
onreply_route[do_save] {
	if ($rs=="200")
		save("location");
}
...
		
```


#### attr_avp (string)


AVP to store specific additional information for each registration.
This information is read from the AVP and stored (in memory, db
or both) at every registrar 'save()'. When a registrar 'lookup()' or
'is_registered()' function is called, the stored information is
pushed into a message branch attribute with the same name as 
*attr_avp* (see $msg.branch.attr() core variable)


When doing parallel call forking, the contact attributes will be 
pushed to the attributes of the corresponding branch


*Default value is NULL.*


```opensips title="Set attr_avp parameter"
# reading attributes from the attr_pvar when doing parallel forking
...
modparam("registrar", "attr_avp", "$avp(attr)")

...
if (is_method("REGISTER")) {
	$avp(attr) = "contact_info";
	save("location");
	exit;
}
...
lookup("location");
# list all resulted branches and their attribute
$var(i) = 0;
while ($(msg.branch.uri[$var(i)])!=NULL) {
	xlog("branch $var(i): $(msg.branch.uri[$var(i)]), attr=$(msg.branch.attr(attr)[$var(i)])\n");
	$var(i) = $var(i) + 1;
}
....
t_on_branch("parallel_fork");
t_relay();
...
branch_route [parallel_fork] {
	xlog("Attributes for branch $T_branch_idx: $tm.branch.attr(attr)\n");
}

		
```


#### gruu_secret (string)


The string that will be used in XORing when generating
temporary GRUUs.


*If not set, 'OpenSIPS' is the default secret.*


```opensips title="Set gruu_secret parameter"
...
modparam("registrar", "gruu_secret", "top_secret")
...
		
```


#### disable_gruu (int)


Globally disable GRUU handling


*Default value is 1 ( GRUU will not be handled ).*


```opensips title="Set gruu_secret parameter"
...
modparam("registrar", "disable_gruu", 0)
...
		
```


#### pn_enable (boolean)


Enable SIP Push Notification support ([RFC 8599](https://tools.ietf.org/html/rfc8599)).
If enabled, Contact header field URIs which include all
[pn ct match params](#pn_ct_match_params-string) will be matched against
existing bindings using only these parameters.  Otherwise,
the module will attempt to match them as usual, using the current
usrloc [matching_mode](../usrloc/README.md#matching_mode-integer).


*Default value is **false**.*


```opensips title="Setting the pn_enable parameter"
...
modparam("registrar", "pn_enable", true)
...
```


#### pn_providers (string)


A list of supported Push Notification providers.  While only three
possible values are defined by RFC 8599 ("apns", "fcm" and "webpush"),
non-standard values may be specified as well.


*Default value is **NULL**
(not set).*


```opensips title="Setting the pn_providers parameter"
...
modparam("registrar", "pn_providers", "apns, fcm, webpush")
...
```


#### pn_ct_match_params (string)


The minimally required list of RFC 8599 parameters (custom ones are
accepted as well) which must be present in a Contact URI and
identically match an existing binding in order for the binding
to be refreshed during a SIP re-REGISTER.  If at least one such
parameter is missing from a Contact header field URI, the module
will fall back to performing regular contact matching.


> [!NOTE]
> If all above PN Contact URI parameters match an existing
> binding, the match is considered to be successful regardless if
> other parts of the SIP URI do not match (e.g. hostname, port,
> other URI parameters, etc.).


After calling *lookup()* or
[afunc pn process purr](#pn_process_purrdomain), the above PN-related
parameters will be automatically stripped from the resulting
Request and Contact URI event parameter, respectively.


*Default value is **"pn-provider, pn-prid, pn-param"**.*


```opensips title="Setting the pn_ct_match_params parameter"
...
modparam("registrar", "pn_ct_match_params", "pn-provider, pn-prid")
...
```


#### pn_pnsreg_interval (integer)


For devices capable of waking up and refreshing their binding on
their own (signified by the *";+sip.pnsreg"*
Contact header field parameter), this setting denotes the
prior-to-expiration interval advertised by the server at which the
device should issue its binding refresh request.


*Default value is **130**
(seconds before expiry).*


```opensips title="Setting the pn_pnsreg_interval parameter"
...
modparam("registrar", "pn_pnsreg_interval", 140)
...

```


#### pn_trigger_interval (integer)


If a binding refresh REGISTER request from a given SIP endpoint does
not arrive within at least [pn trigger interval](#pn_trigger_interval-integer)
seconds prior to expiration (e.g. because the device does not
support *";+sip.pnsreg"* or because of other
error conditions), the [E_UL_CONTACT_REFRESH](../usrloc/README.md#e_ul_contact_refresh)
usrloc event will be triggered.


Once [E_UL_CONTACT_REFRESH](../usrloc/README.md#e_ul_contact_refresh)
is triggered, the script writer should use
the RFC 8599 parameters from the Contact URI in order to generate a
Push Notification request to the PN provider of the device, in
order to cause the device to wake up and re-register.


*Default value is **120**
(seconds before expiry).*


```opensips title="Setting the pn_trigger_interval parameter"
...
modparam("registrar", "pn_trigger_interval", 130)
...

```


#### pn_skip_pn_interval (integer)


Following a successful (re)registration of a contact, this setting
denotes a time interval, in seconds, during which the contact is
assumed to be reachable, so any Push Notifications will be skipped.


*Default value is **0** seconds
(always generate Push Notifications).*


```opensips title="Setting the pn_skip_pn_interval parameter"
...
modparam("registrar", "pn_skip_pn_interval", 10)
...
```


#### pn_refresh_timeout (integer)


This timeout starts counting following a *lookup()* or a
[afunc pn process purr](#pn_process_purrdomain) which
triggers a Push Notification.  The value represents the maximum
allowed sum of the duration required for the Push Notification to
be sent and the duration required for the corresponding
re-registration from the device to arrive.


Once this timeout is exceeded for an initial or a mid-dialog
request, any further re-registrations which match the pending Push
Notification will no longer cause the desired effects. For example:


- pending initial INVITE transactions will complete and will no
longer auto-fork an additional branch for each REGISTER
sent by the callee side
- pending BYE messages will time out and OpenSIPS will attempt to
route them despite not having received a confirmation that the
target device is actually reachable


*Default value is **6** seconds.*


```opensips title="Setting the pn_refresh_timeout parameter"
...
modparam("registrar", "pn_refresh_timeout", 10)
...
```


#### pn_enable_purr (boolean)


Enable the SIP Push Notification mechanism for long-lived dialogs.
If enabled, the registrar will include a
*"+sip.pnspurr"*
Feature-Caps header field tag in 200 OK replies to REGISTER
requests.  This tag represents a unique identifier for the
registration (PURR - Proxy Unique Registration Reference).


During dialog setup, each UA may include, in its Contact header,
the PURR value returned by OpenSIPS during registration.  By
including the PURR (e.g. ";pn-purr=XXX"), an agent indicates that
it expects to be first awoken by a PN before being able to receive
a mid-dialog request sent by the other party.


When enabling this parameter, make sure to also add logic for
[afunc pn process purr](#pn_process_purrdomain).


*Default value is **false**.*


```opensips title="Setting the pn_enable_purr parameter"
...
modparam("registrar", "pn_enable_purr", true)
...
```


### Exported Functions


#### save(domain[, flags[, aor[, ownership_tag]]])


The function processes a REGISTER message. It can add, remove or
modify usrloc records depending on Contact and Expires HFs in the
REGISTER message. On success, 200 OK will be returned listing all
contacts that are currently in usrloc. On an error, error message
will be send with a short description in reason phrase.


Meaning of the parameters is as follows:


- *domain (static string)* - Logical domain within
registrar. If database is used then this must be name of the table which
stores the contacts.
- *flags (string, optional)* - string composed of
one or more of the following flags, comma-separated:

  - *'memory-only'* - (old *m* flag)
save the contacts only in memory cache without no DB operation;
  - *'no-reply'* - (old *r* flag)
do not generate a SIP reply to the current REGISTER request.
  - *'max-contacts=[int]'* - (old *c*
flag) this flag can be used to limit the number of contacts for this
AOR (Address of Record) in the user location database.
Value 0 disables the check. This parameter overrides the
global "max_contacts" module parameter.
  - *'force-registration'* - (old *f*
flag) this flag can be used to force the registration of NEW contacts
even if the maximum number of contacts is reached. In such
a case, older contacts will be removed to make space to the
new ones, without exceeding the maximum allowed number.
This flag makes sense only if "max-contacts" is used.
  - *'matching-mode=[val]'* - (old *M*
flag) How the matching should be performed between the uploaded
contacts (by the currently handled REGISTER) and the
already know contacts (in memory or DB). This options will
be used only for the current operation and can be:
	- *'0'* - contact URI matching
	only
	- *'1'* - contact URI and
	SIP Call-ID matching
	- *'<param_name>'* - only
	the value of the given URI param will be used for
	matching (for example <rinstance>)
  - *'path-off'* - (old *p0* flag)
(Path support - 'off' mode) - The Path header is saved into usrloc,
but is never included in the reply.
  - *'path-lazy'* - (old *p1* flag)
(Path support - lazy mode) The Path header is saved into usrloc, but is only
included in the reply if path support is indicated in the
registration request by the "path" option
of the "Supported" header.
  - *'path-strict'* - (old *p2* flag)
(Path support - strict mode) - The path header is only saved into usrloc,
if path support is indicated in the registration request by the
"path" option of the "Supported"
header. If no path support is indicated, the request is
rejected with "420 - Bad Extension" and the
header "Unsupported: path" is included in
the reply along with the received "Path"
header. This mode is the one recommended by RFC-3327.
  - *'path-received'* - (old *v* flag)
if set, the "received" parameter of the first Path
URI of a registration is set as received-uri and the NAT
branch flag is set for this contact. This is useful if
the registrar is placed behind a SIP loadbalancer, which
passes the nat'ed UAC address as "received"
parameter in it's Path uri.
  - *'only-request-contacts'* - (old *o*
flag) Only include the REGISTER request's Contacts in the 200 OK
reply, in case the registration is successful.  While this
is against RFC 3261, it may be useful in certain scenarios.
  - *'socket-header'* - (old
*s* flag) look into REGISTER request
for a header which contains a socket
description (proto:IP:port). This socket info will be
stored by register instead of the received socket info.
  - *'min-expires=[int]'* - (old
*e* flag) this
flag can be used to set minimum register expiration time.
Values lower than this minimum will be automatically set
to the minimum. Value 0 disables the checking.
This parameter overrides the global
[min expires](#min_expires-integer) module parameter.
  - *'max-expires=[int]'* - (old
*E* flag) this
flag can be used to set maximum register expiration time.
Values higher than this maximum will be automatically set
to the maximum. Value 0 disables the checking.
This parameter overrides the global
[max expires](#max_expires-integer) module parameter.
This parameter is a string composed of a set of flags.
- *aor (string, optional)* - a custom AOR; if missing,
the AOR will be taken from the default place - the TO header URI.
- *ownership_tag (string, optional)* - a cluster-shared
tag (see the clusterer module documentation for more details) which
will be attached to each contact saved from the current request.
This tag is only relevant in clustered user location scenarios and
helps determine the current logical owner node of a contact.  This,
in turn, is useful in order to restrict nodes which are not
currently responsible for this contact from performing certain
actions (for example: incorrectly originating pings from a
non-owned virtual IP address in highly-available setups).


This function can be used from REQUEST_ROUTE and ONREPLY_ROUTE.


If you plan to use the "save()" function in reply route,
please refer to [mcontact avp](#mcontact_avp-string) module parameter.


```opensips title="save usage"
...
# save into 'location', no flags, use default AOR (TO URI)
save("location");
...
# save into 'location', do not update DB, max 5 contacts per AOR,
# use default AOR (TO URI)
save("location","memory-only, max-contacts=5");
...
# save into 'location', no flags, use as AOR the FROM URI
save("location","",$fu);
...
# save into 'location', no DB update, force registration, take AOR from AVP
save("location","memory-only, no-reply", $avp(aor));
...
# save into 'location', mark the contacts with the "vip" ownership tag and
# replicate these contacts to the backup node, which does not currently own "vip"
save("location", , , "vip");
...
```


#### remove(domain, AOR[, [contact][, [next_hop][, [sip_instance], [bflag]]]])


Explicitly remove contacts behind a given address-of-record.


Meaning of the parameters is as follows:


- *domain (static string* - Logical domain within the registrar.
If a database is used, then this must be name of the table which
stores the contacts.
- *AOR (string)* - address-of-record to be searched (SIP URI)
- *contact (string, optional)* - SIP URI filter
for the contact to be removed. This must be the full SIP URI
as used during registered.
- *next_hop (string, optional)* - the next
SIP IP address/hostname on the way back to this contact. See
the section below for details on how the next hop is
computed. Hostnames are resolved before matching.
- *sip_instance (string, optional)* - a
"+sip.instance" value to be used for filtering purposes.
- *blfag (string, optional)* - a
Branch Flag to be used for filtering purposes.


> [!IMPORTANT]
> The IP address of each
> contact (for matching purposes) is computed as follows:
> - a. if a Path header is present, the hostname part of the
> Path URI will be resolved as the contact's IP address.
> - b. otherwise, if by using nathelper, the "Received" value
> (source IP of the next hop) is set for a contact, this
> becomes the chosen hostname to be resolved as the contact's
> IP address.
> - c. otherwise, the "hostname" part of the Contact header
> field URI is chosen to be resolved as the contact's IP
> address.


This function can be used from REQUEST_ROUTE and ONREPLY_ROUTE.


```opensips title="remove usage"
...
# remove all contacts belonging to the "bob" AOR
remove("location", "sip:bob@atlanta.com");
...
# remove only bob's home phone contact
remove("location", "sip:bob@atlanta.com", "sip:bob@46.50.64.78");
...
# remove all bob's phones which are behind "50.60.50.60"
# note that "contact" parameter has to be specified with NULL value even though not used
$var(next_hop) = "50.60.50.60"
remove("location", "sip:bob@atlanta.com", , $var(next_hop));
...
# remove bob's phone with contact "sip:bob@46.50.64.78" that is behind "50.60.50.60"
remove("location", "sip:bob@atlanta.com", "sip:bob@46.50.64.78", "50.60.50.60");
...
# remove all contacts behind bob's mobile device X
remove("location", "sip:bob@atlanta.com", , , "<urn:uuid:e5e68d40-f08a-4600-b82e-ff4d5d8c1a8f>")
```


#### remove_ip_port(IP,Port, domain, [AOR])


Remove all contacts behind a specific IP and Port, optionally filtering by AOR.


Meaning of the parameters is as follows:


- *IP (string)* - IP of the Contact to be removed
- *Port (integer)* - Port of the Contact to be removed
- *domain (static string* - Logical domain within the registrar.
If a database is used, then this must be name of the table which
stores the contacts.
- *AOR (string, optional)* - address-of-record to be searched (SIP URI)


This function can be used from ALL ROUTES.


```opensips title="remove_ip_port usage"
...
# remove all contacts behind 8.8.8.8 port 43213
remove_ip_port("8.8.8.8",43213,"location");
...
# remove only bob's contacts behind the 8.8.8.8:43213 host
remove_ip_port("8.8.8.8",43213,"location","sip:bob@atlanta.com");
...
```


#### lookup(domain [, flags [, aor]])


The functions extracts username from Request-URI and tries to find
all contacts for the username in usrloc. If there are no such
contacts, -1 will be returned.  If there are such contacts,
Request-URI will be overwritten with the contact that has
the highest q value and optionally the rest will be appended to
the message (depending on append_branches parameter value).


If the method_filtering option is enabled, the lookup function
will return only the contacts that support the method of the
processed request.


Meaning of the parameters is as follows:


- *domain (static string)* - Name of table that
should be used for the lookup.
- *flags (string, optional) - string composed of one or more of
the following flags, comma-separated:*

  - *'no-branches'* - (old *b* flag) this
flag controls how the *lookup()* function processes multiple contacts.
If there are
multiple contacts for the given username in usrloc and this
flag is not set, Request-URI will be overwritten with the
highest-q rated contact and the rest will be appended to
sip_msg structure and can be later used by tm for forking. If
the flag is set, only Request-URI will be overwritten
with the highest-q rated contact and the rest will be left
unprocessed.
  - *'to-branches-only'* - (old *B* flag)
this flags forces all found contacts to be uploaded only as branches (in the
destination set) and not at all in the R-URI of the
current message.  Using this option allows the *lookup()* function to
also be used in the context of a SIP reply.
  - *'branch'* - (old *r* flag) this flag
enables searching through existing branches for aor's and expanding
them to contacts. For example, you have got AOR A in your
ruri but you also want to forward your calls to AOR B. In order
to do this, you must put AOR B in a branch, and if this flag
enabled, the function will also expand AOR B to contacts,
which will be put back into the branches. The AOR's that were
in branches before the function call shall be removed.
**WARNING:**
*if you want this flag activated,
the 'no-branches' flag must not be set, because by setting
that flag you won't allow *lookup()* to write in a branch.*
  - *'method-filtering'* - (old *m* flag)
setting this flag will enable contact filtering based on the supported methods
listed in the "Allow" header field during registration.
Contacts which did not present an "Allow" header field during
registration are assumed to support all standard SIP methods.
  - *'ua-filtering=[val]'* (old *u* flag)
(User-Agent filtering) - this flag enables regexp filtering by user-agent.
It's useful with enabled append_branches parameter. The value must use the
format '/regexp/'.
  - *'case-insensitive'* (old *i* flag) -
this flag enables case insensitive filtering for the 'ua-filtering' flag.
  - *'extended-regexp'* - (old *e* flag)
this flag enables using of extended regexp format for the 'ua-filtering' flag.
  - *'global'* (old *g* flag) (Global
lookup) - this flag is only relevant with federated user location clustering.
If set, the *lookup()* function will not only perform the classic
in-memory "search-AoR-and-push-branches" operation, but will
also perform a metadata lookup and append an additional branch
for each returned result. The "in-memory branches" correspond
to local contacts (current location), while the "metadata
branches" correspond to contacts available on one or more of
the remaining locations of the platform.
The AoR metadata consists of the minimally required information
in order for one of the VoIP platform's locations (data
centers) to advertise the presence of a locally registered AoR
for the global platform. Specifically, this consists of two
pieces of information:


the AoR (e.g. "vladimir@federation-cluster")


the home IP (e.g. "10.0.0.223")
  - *'max-ping-latency=[int]'* - (old *y*
flag) maximally accepted contact pinging latency (microseconds). Contacts of an
AoR with a higher latency will be discarded during *lookup()*.
  - *'sort-by-latency'* - (old *Y* flag)
contacts will be picked in ascending order of their last successful
pinging latency (fastest ping -> slowest ping). This flag may
work together with the "max-ping-latency" flag.
- *AOR (string, optional)* - AOR to lookup for; if
missing, the RURI is used as AOR;


Return codes:


- **1** - contacts found and successfully
pushed as branches.  Contacts which required awakening prior to being
reachable are being notified via async Push Notifications.
- **2** - successfully started at least one
async Push Notification for the found contacts, however no extra branches
were populated (i.e. there is no need to call t_relay()).
- **-1** - no contact found.
- **-2** - contacts found, but neither of them
supports the current SIP method.
- **-3** - internal error during processing.


This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.


```opensips title="lookup usage"
...
lookup("location");  # simple lookup
   #or
lookup("location", "method-filtering"); # lookup with method filtering
   #or
lookup("location", "branch"); # lookup with aor branch search;
						# all contacts except the first one shall be put
						# in the branches
   #or
lookup("location", "ua-filtering=/phone/i"); # lookup with user-agent filtering
   #or
lookup("location", "", $var(aor)); # simple lookup with AOR from var
switch ($retcode) {
    case -1:
    case -3:
        sl_send_reply(404, "Not Found");
        exit;
    case -2:
        sl_send_reply(405, "Not Found");
        exit;
};
...
```


#### is_registered(domain ,[AOR])


The function returns true if an AOR is registered, false otherwise.
The function does not modify the message being process.


> [!NOTE]
> If called for a reply (from onreply_route), you must pass an
> AOR (as parameter), otherwise the function will fail.


Meaning of the parameters is as follows:


- *domain (static string)* - Name of table that
should be used for the lookup.
- *AOR (string, optional)* - AOR to lookup for; if
missing, the source if the AOR is the "To" header for REGISTER
request, "From" header for any other sip request.


This function can be used from REQUEST_ROUTE, FAILURE_ROUTE,
BRANCH_ROUTE, ONREPLY_ROUTE, LOCAL_ROUTE.


```opensips title="is_registered usage"
...
/**/
if (is_method("REGISTER")) {
	/* automatically uses the URI from the To header */
	if (is_registered("location")) {
		xlog("this AOR is registered\n")
		...
	}
};
/* check the From uri whether this aor is registered or not */
if (is_registered("location",$fu)) {
	xlog("caller is registered\n");
}
...
```


#### is_contact_registered(domain ,[AOR],[contact],[callid])


The function returns true if a contact and/or a callid from a certain AOR is registered, false otherwise.
The function does not modify the message being process.


Meaning of the parameters is as follows:


- *domain (static string)* - Name of table that should be
used for the lookup.
- *AOR (string, optional)* - AOR to lookup for; if
missing, the source if the AOR is the "To" header for REGISTER
request, "From" header for any other sip request.
- *contact (contact, optional)* (optional)- SIP
URI to check if there is a registration with this URI as cotact
(this may help you to make distinction between multiple 
registrations for the same user/AOR).
- *callid (string, optional)* - callid to check if a
contact if registered with this callid (this may help you to
make distinction between newly registered contact (callid
not registered so far) and re-registration (callid already
registered).


This function can be used from REQUEST_ROUTE, FAILURE_ROUTE,
BRANCH_ROUTE, ONREPLY_ROUTE, LOCAL_ROUTE.


```opensips title="is_contact_registered usage"
...
/* block users which are not registered... */
if (is_method("INVITE")) {
	if (!is_contact_registered("location")) {
		sl_send_reply(401, "Unauthorized");
		...
	}
}

/* ... or check whether the 2nd Contact URI is registered or not */
if (is_method("INVITE")) {
	if (is_contact_registered("location", $fu, $(ct.fields(uri)[1])))
		xlog("caller is registered\n");
}
...
```


#### is_ip_registered(domain ,[AOR],IPvar,[PORTvar])


The function returns true if there is at least one contact that has
been registered from the IP in the IPvar variable ( and from the optional
PORTvar variable ). 
The IP is matched against the received host, if it exists, or the contact host otherwise.
This function does not modify the message being process. This function
replaces the old "is_other_contact" function.


Meaning of the parameters is as follows:


- *domain (static string)* - Name of table that should be
used for the lookup.
- *AOR (string, optional)* - AOR to lookup for; if
missing, the source if the AOR is the "To" header for REGISTER
request, "From" header for any other sip request.
- *IPvar (var)* - the variable containing the IP matched against
the contact host or the received host (see above). If the
*IPvar* is an AVP containing multiple values/IPs,
then all the values are checked.
- *PORTvar (var, optional)* - the variable containing the port to be
matched against the contact host or the received host (see above). If the
*IPvar* is an AVP containing multiple values/IPs, then the PORTvar
is expected to contain the same number of entries, and all the values are checked.


This function can be used from REQUEST_ROUTE, FAILURE_ROUTE,
BRANCH_ROUTE, ONREPLY_ROUTE, LOCAL_ROUTE.


```opensips title="is_ip_registered usage"
...
/* check the source ip  whether it is already registered */
if (is_method("REGISTER")) {
	if (is_ip_registered("location",$tu,$si)) {
		xlog("already registered from this ip\n");
		...
	}
};
...
```


#### add_sock_hdr(hdr_name)


Adds to the current REGISTER request a new header with
"hdr_name" which contains the description of the
received socket (proto:ip:port)


This makes sense only in multiple replicated servers scenarios.


Meaning of the parameters is as follows:


- *hdr_name (string)* - header name to be used.


This function can be used from REQUEST_ROUTE.


```opensips title="add_sock_hdr usage"
...
add_sock_hdr("Sock-Info");
...
```


### Exported Asynchronous Functions


#### pn_process_purr(domain)


Perform mid-dialog request processing, according to RFC 8599.  For
such requests, search the R-URI and topmost Route header field URI for
a *";pn-purr"* parameter value that both matches the
OpenSIPS PURR format and corresponds to an usrloc registration. Once a
usrloc contact is located, trigger an [E_UL_CONTACT_REFRESH](../usrloc/README.md#e_ul_contact_refresh)
event and place the request on async hold for at most
[pn refresh timeout](#pn_refresh_timeout-integer) seconds, until a matching
REGISTER request arrives.


If processing ends before triggering the Push Notification, the request
will no longer be put on async hold, with the resume route being
immediately called.


Meaning of the parameters is as follows:


- *domain (static string)* - Logical domain within
registrar.  If a database is used, then this must be name of the
table which stores the contacts.


**Return Codes**


- **1** - Success, PN was launched.
- **2** - Success,
but PN was not launched (due to missing PURR, foreign PURR or
offline contact)
- **-1** - Internal Error


```opensips title="async pn_process_purr() usage"
route {
	...
	if (has_totag()) {
		if (is_method("ACK") && t_check_trans()) {
			t_relay();
			exit;
		}

		if (!loose_route()) {
			send_reply(404, "Not Found");
			exit;
		}

		if (!is_method("ACK"))
			async (pn_process_purr("location"), resume_route);

		route(relay);
		exit;
	}
}

route [resume_route] {
	$var(rc) = $rc;
	xlog("pn_process_purr() finished with $var(rc)\n");

	...
}
```


### Exported Statistics


#### max_expires


Value of max_expires parameter.


#### max_contacts


The value of max_contacts parameter.


#### defaults_expires


The value of default_expires parameter.


#### accepted_regs


Number of accepted registrations.


#### rejected_regs


Number of rejected registrations.


## Frequently Asked Questions


**Q: What happened with the old "append_branch" module parameter?**


It was removed as global option, as the "lookup" 
function takes this option via the flag "b" (append Branches) 
See the documentation of the "lookup" function.


**Q: What happened with the old "method_filtering" module parameter?**


It was removed as global option, as the "lookup" 
function takes this option via the flag "m" (Method filtering) 
See the documentation of the "lookup" function.


**Q: What happened with the old "sock_flag" module parameter?**


It was removed as global option, as the "save" 
function takes this option via the flag "s" (Socket header) 
See the documentation of the "save" function.


**Q: What happened with the old "use_path" and "path_mode" module parameters?**


They were removed as global option, as the "save" 
function takes these options via the flag "px" (path support) 
See the documentation of the "save" function.


**Q: What happened with the old "path_use_received" module parameter?**


It was removed as global option, as the "save" 
function takes this option via the flag "v" (path receiVed) 
See the documentation of the "save" function.


**Q: What happened with the old "nat_flag" module parameter?**


It was removed, as the module internally loads this value from the
"USRLOC" module (see the "nat_bflag"
USRLOC parameter).


**Q: What happened with the old "use_domain" module parameter?**


It was removed, as the module internally loads this option from the
"USRLOC" module. This was done in order to simplify the
configuration.


**Q: What happened with the old "save_noreply" and "save_memory" functions?**


There functions were merged into the new 
"save(domain,flags)" functions. If a reply should be
sent or if the DB should be updated also is controlled via the
flags.


**Q: Where can I find more about OpenSIPS?**


Take a look at [https://opensips.org/](https://opensips.org/).


**Q: Where can I post a question about this module?**


First at all check if your question was already answered on one of
our mailing lists:

E-mails regarding any stable OpenSIPS release should be sent to 
users@lists.opensips.org and e-mails regarding development versions
should be sent to devel@lists.opensips.org.

If you want to keep the mail private, send it to 
users@lists.opensips.org.


**Q: How can I report a bug?**


Please follow the guidelines provided at:
[https://github.com/OpenSIPS/opensips/issues](https://github.com/OpenSIPS/opensips/issues).


**Q: What happened to the desc_time_order parameter?**


It was removed, as its functionality was mmigrate into usrloc
module, were there is a parameter with the same name.
<!-- CONTRIBUTORS -->

### License

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