# &adminguide;

## Overview

The module contains REGISTER processing logic. The actual location database is managed by the USRLOC module.

### PATH support

The Register module includes Path support (according to RFC 3327) for usage in registrars and home-proxies.

If path support is enabled in the registrar module, a call to save(...) stores the values of the Path Header(s) along with the contact into usrloc. There are three modes regarding the reply to a REGISTER including 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 header field.

- 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 header field either in front of the first Route header field, or after the last Via header field 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 beside setting the registrar-parameters use_path and path_mode.

### GRUU Support

GRUU (RFC5627) is supported with both public and temporary addresses.

The public GRUU is built based on the '+sip.instance' UUID parameter as recommended by RFC.

The temporary GRUU is built based on internal SRUID (unique id generator) and it is kept the same for the duration of contact validity.

## Dependencies

### &kamailio; Modules

The following modules must be loaded before this module:

- usrloc - User Location Module.

- sl - Stateless Replies.

### External Libraries or Applications

The following libraries or applications must be installed before running &kamailio; with this module loaded:

- None.

## Parameters

### `default_expires` (integer)

If the processed message contains neither Expires header fields 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). If it is set to a lower value than the min_expires parameter then it will be ignored. This parameter can be modified via ser config framework. A random value in a specific interval can be selected by using the default_expires_range parameter

Default value is 3600.

#### Set `default_expires` parameter

    ...
    modparam("registrar", "default_expires", 1800)
    ...

### `default_expires_range` (integer)

This parameter specifies that the expiry used for newly created usrloc records are not fixed, but a random value in the interval [default_expires-default_expires_range%, default_expires]. The value is between 0 and 100 and represent the maximum percentage from expires that will be subtracted when computing the value. Default is 0, meaning default_expires is left unmodified. This parameter can be modified via the &kamailio; config framework.

Default value is 0.

#### Set `default_expires_range` parameter

    ...
    modparam("registrar", "default_expires_range", 30) # expires within [0.7*default_expires .. default_expires]
    ...

### `expires_range` (integer)

Similar to default_expires_range, but it applies to the incoming expires value. Default in 0, meaning the expires is left unmodified. This parameter can be modified via the &kamailio; config framework.

Default value is 0.

#### Set `expires_range` parameter

    ...
    modparam("registrar", "expires_range", 30) # expires within [0.7*expires .. expires]
    ...

### `min_expires` (integer)

The minimum expires value of a Contact. Values lower than this minimum will be either set to the minimum or 423 response is sent back. Value 0 disables the checking. This parameter can be modified via the &kamailio; config framework.

Default value is 60.

#### Set `min_expires` parameter

    ...
    modparam("registrar", "min_expires", 60)
    ...

### `min_expires_mode` (integer)

Control what to do when expires value in REGISTER request is lower than min_expires parameter. If set to 0, expires is set to min_expires. If set to 1, then 423 Interval Too Brief is sent back.

Default value is 0.

#### Set `min_expires_mode` parameter

    ...
    modparam("registrar", "min_expires_mode", 1)
    ...

### `max_expires` (integer)

The maximum accepted expires value of a Contact, values higher than this maximum will be automatically set to the maximum. Value 0 disables the checking. This parameter can be modified via the &kamailio; config framework.

Default value is 0.

#### Set `max_expires` parameter

    ...
    modparam("registrar", "max_expires", 120)
    ...

### `default_q` (integer)

The parameter represents default q value for new contacts. Because &kamailio; 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. This parameter can be modified via the &kamailio; config framework.

Default value is 0.

#### Set `default_q` parameter

    ...
    modparam("registrar", "default_q", 1000)
    ...

### `realm_prefix` (string)

Prefix to be automatically stripped 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. This parameter can be modified via the &kamailio; config framework.

Default value is NULL (none).

#### Set `realm_prefix` parameter

    ...
    modparam("registrar", "realm_prefix", "sip.")
    ...

### `append_branches` (integer)

The parameter controls how lookup function processes multiple contacts. If there are multiple contacts for the given username in usrloc and this parameter is set to 1, Request-URI will be overwritten with the highest-q rated contact. The rest will be appended to sip_msg structure and can be later used by tm for forking. If the parameter is set to 0, only Request-URI will be overwritten with the highest-q rated contact and the rest will be left unprocessed. This parameter can be modified via &kamailio; config framework.

Default value is 1.

#### Set `append_branches` parameter

    ...
    modparam("registrar", "append_branches", 0)
    ...

### `aor_avp` (str)

This module parameter has been removed. Use the 'uri' parameter from functions (e.g., save, lookup, registered).

### `case_sensitive` (integer)

If set to 1 then AOR comparison and also storing will be case sensitive, if set to 0 then AOR comparison and storing will be case insensitive. This is recommended. This parameter can be modified via &kamailio; config framework.

Default value is 0.

#### Set `case_sensitive` parameter

    ...
    modparam("registrar", "case_sensitive", 1)
    ...

### `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 transport protocol of the REGISTER message being processed.

The value of this parameter should be the same as the value of corresponding parameter of nathelper module.

Default value is "NULL" (disabled).

#### Set `received_avp` parameter

    ...
    modparam("registrar", "received_avp", "$avp(s:rcv)")
    ...

### `received_param` (string)

The name of the parameter that will be appended to Contact URI's of 200 OK when the received URI was set by the nathelper module. If the value is an empty string, then the parameter is not appended anymore.

Default value is "received".

#### Set `received_param` parameter

    ...
    modparam("registrar", "received_param", "rcv")
    ...

### `max_contacts` (integer)

The parameter can be used to limit the number of contacts per AOR (Address of Record) in the user location database. If the maximum number of contacts is exceeded, &kamailio; will not accept the registration and send an error response. Value 0 disables the check. This parameter can be modified via the &kamailio; config framework. (Please also check the flag for `save()` if you only want only one active registration).

Default value is 0.

#### Set `max_contacts` parameter

    ...
    # Allow no more than 10 contacts per AOR
    modparam("registrar", "max_contacts", 10)
    ...

### `retry_after` (integer)

The registrar can generate a 5xx reply to REGISTER requests 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. This parameter can be modified via the &kamailio; config framework.

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).

#### Set `retry_after` parameter

    ...
    modparam("registrar", "retry_after", 30)
    ...

### `sock_flag` (integer)

Message flag to signal to the registrar module to look into REGISTER request for a header which contains a socket description (IP:port). This socket info will be stored by registrar instead of the received socket info.

This makes sense only in multiple replicated servers scenarios.

Default value is -1 (no flag).

#### Set `sock_flag` parameter

    ...
    modparam("registrar", "sock_flag", 18)
    ...

### `sock_hdr_name` (string)

Header which contains a socket description (proto:IP:port) to override the received socket info. The header will be read only if the flag sock_flag is set.

This makes sense only in multiple replicated servers scenarios.

Default value is NULL.

#### Set `sock_hdr_name` parameter

    ...
    modparam("registrar", "sock_hdr_name", "Sock-Info")
    ...

### `sock_mode` (integer)

If set to 1, the server stores the advertised address in socket field, instead of bind address.

This could be useful when kamailio is installed behind NAT and it is necessary to store its public IP instead socket on which the register request was received.

Default value is 0 (store bind address).

#### Set `sock_mode` parameter

    ...
    modparam("registrar", "sock_mode", 1)
    ...

### `method_filtering` (integer)

Tells if the contact filtering based on supported methods should be performed during lookup on initial requests without to-tag. It's enabled only if it has a non zero value. Supported methods are listed in the Allow: header in the REGISTER message and stored in the location database.

Default value is 0 (disabled).

#### Set `method_filtering` parameter

    ...
    modparam("registrar", "method_filtering", 1)
    ...

### `use_path` (integer)

If set to 1, the Path: header is handled according to the parameter. This parameter can be modified via &kamailio; config framework. path_mode.

Default value is 0 (disabled).

#### Set `use_path` parameter

    ...
    modparam("registrar", "use_path", 1)
    ...

### `path_mode` (integer)

The registrar module implements three different modes regarding the response to a registration which includes one or more Path headers:

- 0 - The Path header is saved into usrloc, but is not included in the reply.

- 1 - 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 in the Supported: header.

- 2 - 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.

Default value is 2.

#### Set `path_mode` parameter

    ...
    modparam("registrar", "path_mode", 0)
    ...

### `path_use_received` (integer)

If set to 1, 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 its Path uri.

Default value is 0 (disabled).

#### Set `path_use_received` parameter

    ...
    modparam("registrar", "path_use_received", 1)
    ...

### `path_check_local` (integer)

If set to 1, when performing a lookup the Path (if present) is evaluated and if the first hop is local (according to myself test), we skip it to avoid unnecessary looping.

This is useful if multiple servers are sharing a common location database, each saving contacts with their local address as the Path.

Default value is 0 (disabled).

#### Set `path_check_local` parameter

    ...
    modparam("registrar", "path_check_local", 1)
    ...

### `reg_callid_avp` (string)

obsolete. use match_option in registered function

If reg_callid_avp is defined and populated when the `registered()` is invoked, the result is TRUE only if an active registration with the specified callID is found.

Default value is NULL (disabled).

#### Set `reg_callid_avp` parameter

    ...
    modparam("registrar", "reg_callid_avp", "$avp(s:avp)")
    ...

### `xavp_cfg` (string)

Defines the name of XAVP class to store runtime module config values. The values are stored as inner XAVPs, like $xavp(class=>attribute). Valid inner XAVP names:

- match_callid - filter contacts by callid. Used in registered().

- match_contact - filter contacts by contact. Used in registered().

- match_received - filter contacts by received. Used in registered().

- rlf_bflags - filter contacts by branch flags. Used in lookup().

- q - q value of contact (integer 0-1000). It overrides q value given in contact header and default_q parameter. Used in save().

- expires - the expires value, to overwrite the value from SIP headers. Used in save().

- max_contacts - the number of maximum contacts to be stored for the current registration AoR. It overwrites the 'max_contacts' module parameter value. Used in save().

- socket - the string representing the socket on which the register request was received, as alternative to using the sock_hdr. Used in save().

- tcpconn_id This can be set with $conid, the TCP connection ID of the connection the current message. This is useful when calling save() on a reply route to set the connecion of the original request. Used in save().

For example if this parameter is set to 'reg', then the number of maximum contacts can be set in $xavp(reg=>max_contacts).

Default value is NULL (disabled).

#### Set `xavp_cfg` parameter

    ...
    modparam("registrar", "xavp_cfg", "reg")
    ...
    request_route {
        ...
        $xavp(reg=>max_contacts) = 4;
        $xavp(reg[0]=>expires) = 600;
        save("location");
        ...
    }
    ...

### `xavp_rcd` (string)

Defines the name of XAVP class to store details from the location records. The values are stored as inner XAVPs, like $xavp(class[0]=>attribute). Valid inner XAVP names:

- ruid - the record's internal unique id.

- contact - the record's contact value.

- expires - the record's expires value.

- received - the record's received value.

- path - the record's path value.

For example. if this parameter is set to 'ulrcd', then values are set in:

- $xavp(ulrcd[0]=>ruid)

- $xavp(ulrcd[0]=>contact)

- $xavp(ulrcd[0]=>received)

- $xavp(ulrcd[0]=>path)

Default value is NULL (disabled).

#### Set `xavp_rcd` parameter

    ...
    modparam("registrar", "xavp_rcd", "ulrcd")
    ...

### `xavp_rcd_mask` (int)

Defines what values to skip when xavp_rcd is stored.

- 1 - ruid

- 2 - contact

- 4 - expires

- 8 - received

- 16 - path

Default value is 0 (none).

#### Set `xavp_rcd_mask` parameter

    ...
    # skip path value
    modparam("registrar", "xavp_rcd_mask", 16)
    ...
    # skip path and expires values
    modparam("registrar", "xavp_rcd_mask", 20)
    ...

### `gruu_enabled` (integer)

If set to 1 and the +sip.instance parameter to Contact header of REGISTER is present, then the value of the parameter is saved to location and pub-gruu and temp-gruu addresses are generated.

Set it to 0 if you want to ignore GRUU extensions in REGISTER.

Default value is 1 (enabled).

#### Set `gruu_enabled` parameter

    ...
    modparam("registrar", "gruu_enabled", 0)
    ...

### `outbound_mode` (integer)

If set to 0 this module will accept REGISTER requests that do not contain a Supported: header with the outbound options-tag. The 200 OK response to REGISTER requests that this module generates will not contain Require: or Supported: headers with the outbound options-tag. If the client has a Require: header with the outbound options tag the REGISTER will be rejected with a 420 Bad Extension response.

If set to 1 this module will accept REGISTER requests that do not contain a Supported: header with the outbound options-tag and REGISTER requests that do contain a Supported: or Requires: header with the outbound options-tag. When the client supports outbound the appropriate RFC5626 procedures will be followed.

If set to 2 this module will reject REGISTER requests that do not contain a Supported: header with the outbound options-tag. When the client supports outbound the appropriate RFC5626 procedures will be followed.

Default value is 0.

#### Set `outbound_mode` parameter

    ...
    modparam("registrar", "outbound_mode", 2)
    ...

### `regid_mode` (integer)

If set to 0 this module will ignore the regid contact param when saving REGISTER request if the request does not indicate support for outbound.

If set to 1 this module will use regid contact param (if present) when saving REGISTER request even if REGISTER request does not indicate support for outbound.

Default value is 0.

#### Set `regid_mode` parameter

    ...
    modparam("registrar", "regid_mode", 1)
    ...

### `flow_timer` (integer)

If set to 0 then this module will not add a Flow-Timer: header to 200 OK responses to REGISTER requests.

If set to > 0 then this module will add a Flow-Timer: header containing this value to 200 OK responses to REGISTER requests. This parameter may only be set to a value > 0 when outbound_mode is set to 1 or 2.

When set to a value greater than 0 this parameter should be set to slightly less than the connection timeout value between the UAC and the network (this corresponds to the core tcp_connection_lifetime option and websocket keepalive_timeout modparam). This parameter is most useful when you have a single edge proxy/registrar or if you have an edge proxy that cannot modify responses. If you are using a separate edge proxy you should consider leaving this parameter set to 0 and adding the Flow-Timer: header on the edge proxy as this allows you to keep all of the timer values for a specific flow in one configuration.

Default value is 0.

#### Set `flow_timer` parameter

    ...
    modparam("registrar", "flow_timer", 25)
    ...

### `contact_max_size` (integer)

Max size of URIs in Contact: header.

The size of URIs in Contact: headers are checked to be lower or equal to this value. A warning is logged and a 400 Bad Request is sent in response to REGISTER requests with contact URIs that are longer than this value.

If a database is used then you must make sure that your database model supports strings of the configured size in the column contact of the table specified in save() function.

Default value is 512.

#### Set `contact_max_size` parameter

    ...
    modparam("registrar", "contact_max_size", 1024)
    ...

### `event_callback` (str)

The name of the function in the KEMI configuration file (embedded scripting language such as Lua, Python, ...) to be executed instead of event_route[...] blocks.

The function receives a string parameter with the name of the event. The only possible value currently is 'usrloc:contact-expired'.

Default value is 'empty' (no function is executed for events).

#### Set `event_callback` parameter

    ...
    modparam("registrar", "event_callback", "ksr_registrar_event")
    ...
    -- event callback function implemented in Lua
    function ksr_registrar_event(evname)
        KSR.info( "Expired contact for " .. KSR.pv.getw("$ulc(exp=>aor)") .. "\n");
    	return 1;
    end
    ...

### `lookup_filter_mode` (int)

Control what filters should be applied to lookup(...) operations. It can be a combination (sum) of the next values:

- 1 - apply the branch flags filter - return only contact records with branch flags matching at least one set inside xavp specified by xavp_cfg parameter with inner name rlf_bflags - e.g., $xavp(reg=>rlf_bflags).

- 2 - apply the active tcp connection filter - return only contact records that have the associated TCP/TLS/WSS connection active. UDP and SCTP contacts are not filtered, all are returned.

Default value is NULL (disabled).

#### Set `xavp_cfg` parameter

    ...
    modparam("registrar", "xavp_cfg", "reg")
    modparam("registrar", "lookup_filter_mode", 1)
    ...
    request_route {
        ...
        $xavp(reg=>rlf_bflags) = 8;
        if(lookup("location")) { ... }
        ...
    }
    ...

### `use_expired_contacts` (int)

Allow/Disallow the usage of the expired contacts.

- 0 Disallow the usage of the expired contacts.

- 1 Allow the usage of the expired contacts.

Default value is 0 (Disallow).

#### Set `use_expired_contacts` parameter

    ...
    modparam("registrar", "use_expired_contacts", 1)
    ...

    kamctl rpc cfg.set_now_int registrar use_expired_contacts 1
    kamctl rpc cfg.set_now_int registrar use_expired_contacts 0

## Functions

### `save(domain, [, flags [, uri]])`

The function processes a REGISTER message. It can add, remove or modify location records (in usrloc) depending on Contact and Expires header fields in the REGISTER message. On success and when called from the REQUEST_ROUTE, 200 OK will be returned listing all contacts that are currently in the location database. As a side effect, also branch flags are stored in usrloc. On an error, an error message will be sent with a short description in reason phrase.

Meaning of the parameters is as follows:

- domain - Logical domain within the registrar. If a database is used then this must be name of the table which stores the contacts.

- flags (optional) - the value may be a bitwise OR of the following flags:

  - 0x01 - save the contacts only in memory cache with no DB operation;

  - 0x02 - do not generate a SIP reply to the current REGISTER request. When used in ONREPLY_ROUTE, this parameter is obsolete.

  - 0x04 - store and maintain one contact per AoR. If there are other contact addresses for AoR not matching current registration, remove them. This mode ensures one contact per AoR (user).

  - 0x08 - Do not apply expires_range or default_expires_range to this registration.

  - 0x10 - prepare the headers for reply, used only if flag 0x02 is set.

  The flags may be given in decimal or hexadecimal format.

- uri (optional - flags param has to be set and can be 0 for default behavior) - SIP URI to be used instead of To header URI. It can be a dynamic string with pseudo-variables.

Return codes:

- -2 - error, too many contacts for AOR.

- -1 - error.

- 1 - contacts inserted.

- 2 - contacts updated.

- 3 - contacts deleted.

- 4 - contacts returned.

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE and REPLY_ROUTE.

#### `save` usage

    ...
    save("location");
    save("location", "0x01");
    save("location", "0x00", "sip:test@kamailio.org");
    ...

### `lookup(domain [, uri])`

The lookup function extracts username and/or domain 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). As a side effect, also branch flags are restored from usrloc.

If the `method_filtering` option is enabled and request is initial request without to-tag, the `lookup` function will return only the contacts that support the method of the processed request.

Meaning of the parameters is as follows:

- domain - Name of table that should be used for the lookup.

- uri (optional) - SIP URI to be used instead of R-URI. It can be a dynamic string with pseudo-variables.

Return codes:

- 1 - contacts found and returned.

- -1 - no contact found.

- -2 - contacts found, but method not supported.

- -3 - internal error during processing.

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.

#### `lookup` usage

    ...
    lookup("location");
    			switch ($retcode) {:1

        case -1:
        case -3:
            sl_send_reply("404", "Not Found");
            exit;
        case -2:
            sl_send_reply("405", "Not Found");
            exit;
    };
    ...

### `lookup_to_dset(domain [, uri])`

Similar to lookup(...), but push the location contacts to destination set, without changing the R-URI (first branch not changed, it creates additional branches). For the meaning of the parameters and the return codes, see the documentation for lookup(...) function.

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.

#### `lookup_to_dset` usage

    ...
    lookup_to_dset("location");
    ...

### `lookup_branches(domain)`

The function performs lookup(domain) on r-uri and additional branches (only branches that have no other attributes set than uri).

Meaning of the parameters is as follows:

- domain - Name of table that should be used for the lookup.

Return codes are propagated from the `lookup(domain)` function.

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.

#### `lookup_branches` usage

    ...
    lookup_branches("location");
    ...

### `lookup_xavp(ultable, uri, rxname, cxname)`

Similar to lookup(...), but store the location record attributes in XAVPs. Note that not all contact record fields are stored

Meaning of the parameters:

- ultable - name of the usrloc table that is used for the lookup.

- uri - the URI to be searched in location table.

- rxname - name of the XAVP to store record attributes. These are:

  - aor - the address of record.

  - count - the number of contacts.

- cxname - name of the XAVP to store content attributes, name mapping is done from the perspective of using them to send out SIP requests. These are:

  - uri - the contact address.

  - socket - the socket of the contact record.

  - dsturi - the destination uri of the contact record (the received field in location contact).

This function can be used from ANY_ROUTE.

#### `lookup_xavp` usage

    ...
    lookup_xavp("location", "$fu", "rul", "cul");
    xinfo("aor: $xavp(rul=>aor)\n");
    xinfo("number of contacts: $xavp(rul=>count)\n");
    xinfo("first contact record - uri: $xavp(cul=>uri)\n");
    xinfo("first contact record - socket: $xavp(cul=>socket)\n");
    ...

### `registered(domain [, uri [, match_option [, match_action]]])`

The function returns true if the AOR in the URI is registered, false otherwise. The function does not modify the message being processed, it neither rewrites the Request-URI if a contact is found nor append branches. If uri parameter is not provided, then it considered to be the Request-URI for SIP requests and To-URI for SIP replies.

Meaning of the parameters is as follows:

- domain - Name of table that should be used for the lookup.

- uri (optional) - SIP URI to be used instead of Request/To-URI. It can be a dynamic string with pseudo-variables.

- match_option (optional) - flag parameter to restrict contact search. use xavp_cfg to set the values to compare to.

  flag values is as follows:

  - 1 - match_callid

  - 2 - match_received

  - 4 - match_contact

- match_action (optional) - actions to perform when match is positive.

  flag values is as follows:

  - 1 - restore the xavps associated with the matched contact

  - 2 - skip adding the matched location record attributes to xavp_rcd (e.g., the ruid, contact, received, ...)

This function can be used from ANY_ROUTE.

#### `registered` usage

    ...
    if (registered("location")) {
    	sl_send_reply("100", "Trying");
    	...
    };
    ...
    $xavp(regcfg=>match_received) = $su;
    if (registered("location","$rz:$Au", 2)) {
    	sl_send_reply("100", "Trying");
    	...
    };
    ...

### `add_sock_hdr(hdr_name)`

Adds a new header to the current REGISTER request 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 - header name to be used, it can be a static string or contain variables.

This function can be used from REQUEST_ROUTE.

#### `add_sock_hdr` usage

    ...
    add_sock_hdr("Sock-Info");
    ...

### `unregister(domain, uri[, ruid])`

The function removes contacts associated with 'uri' from the location database. If 'ruid' is provided a specific contact is removed, if 'ruid' is not provided all the current contacts are removed. If 'ruid' is provided and the usrloc module is using db_mode=3, 'uri' does not need to be given and can be empty string.

Meaning of the parameters is as follows:

- domain - Name of table that should be used for the lookup or contact addresses.

- uri - The SIP URI address of the user which to remove the contact addresses for. It can contain pseudo-variables that are evaluated at runtime.

- ruid - The record unique ID for a specific contact to be removed. It can contain pseudo-variables that are evaluated at runtime.

This function can be used from ANY_ROUTE.

Return values:

- 0 - Successfully deleted contact(s)

- -1 - Failed to extract or parse address of record from argument

- -2 - Error in unregistering user

- -3 - Contacts for AOR not found

#### `unregister` usage

    ...
    unregister("location", "$ru");
    unregister("location", "sip:user@kamailio.org");
    unregister("location", "$ru", "$ulc(caller=>ruid)");
    unregister("location", "", "$ruid");
    ...

### `reg_fetch_contacts(domain, uri, profile)`

The function fetches the contacts for 'uri' from table 'domain' to pseudo-variable $ulc(profile).

Meaning of the parameters is as follows:

- domain - Name of table that should be used for the lookup of contact addresses.

- uri - The SIP URI address of the user which to fetch the contact addresses for. It can contain pseudo-variables that are evaluated at runtime.

- profile - Name of $ulc pseudo-variable profile that will store the fetched contacts. It is a static string.

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.

#### `reg_fetch_contacts` usage

    ...
    reg_fetch_contacts("location", "$ru", "callee");
    reg_fetch_contacts("location", "sip:user@kamailio.org", "caller");
    ...

### `reg_free_contacts(profile)`

The function frees the contacts from pseudo-variable $ulc(profile). Should be called to release the content of a profile. Anyhow, fetching a new contact addresses set over a profile will release any existing data in that profile.

Meaning of the parameters is as follows:

- profile - Name of $ulc pseudo-variable profile that stores fetched contacts. It is a static string.

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.

#### `reg_free_contacts` usage

    ...
    reg_free_contacts("callee");
    ...

### `reg_send_reply()`

The function sends the SIP reply that is normally sent by save(...), but that was skipped due to flag 0x2. It must be used after save(..., "0x2"). Practically it allows saving registration to location table, do other operations and then send the reply.

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.

#### `reg_send_reply` usage

    ...
    save("location", "0x2");
    ...
    reg_send_reply();
    ...

### `reg_from_user(ultable, uri, mode)`

The function returns true if the SIP message comes from the user identified by 'uri' parameter by matching the associated location records. The matching is done with the field 'received' if it is set, otherwise with the contact address.

Meaning of the parameters is as follows:

- ultable - user location table (e.g., 'location')

- uri - SIP URI to identify the location records to match against.

- mode - matching mode (int) - host part (IP address) is matched always. If mode has bit 1 set (value 1), then the port is matched as well. If mode has bit 2 set (value 2), then the protocol is matched as well.

This function can be used from ANY_ROUTE.

#### `reg_from_user` usage

    ...
    if(reg_from_user("location", "sip:alice@server.com", "0")) {
        # message coming from where 'alice' sent before a REGISTER request
    }
    ...

## Event Routes

### `event_route[usrloc:contact-expired]`

Executed when a contact in location table has expired. The variable $ulc(exp=>...) is filled with the attributes of the expired contact.

#### `event_route[usrloc:contact-expired]` usage

    ...
    event_route[usrloc:contact-expired] {
        xlog("expired contact for $ulc(exp=>aor)\n");
    }
    ...

## Statistics

### `max_expires`

Value of max_expires parameter.

### `max_contacts`

The value of max_contacts parameter.

### `default_expires`

The value of default_expires parameter.

### `accepted_regs`

Number of accepted registrations.

### `rejected_regs`

Number of rejected registrations.

## Pseudo Variables

### `$ulc(profile=>attr)`

Access the attributes of contact addresses stored in 'profile'. It must be used after a call of reg_fetch_contacts().

The profile has to be one of the values used with reg_fetch_contacts().

The attr can be:

- aor - address of record

- domain - used location domain/table name

- aorhash - hash id for the record

- addr - contact address

- path - path vector

- received - received address

- expires - expires value

- callid - call-id header value

- q - the q value

- cseq - the cseq value

- flags - flags value

- cflags - cflags value

- user_agent - user agent

- socket - local socket

- modified - last modified time

- methods - methods value

- count - number of contacts

- ruid - record unique ID

- regid - reg-id value

- instance - instance value

- conid - TCP socket internal connection ID ($null if UDP)

- server_id - server_id value

The pseudo-variable accepts positive index value to access a specific contact record.

#### `$ulc(name)` usage

    ...
    if(reg_fetch_contacts("location", "$fu", "caller"))
    {
      xlog("caller=>aor: $(ulc(caller=>aor))\n");
      xlog("caller=>domain: $(ulc(caller=>domain))\n");
      xlog("caller=>aorhash $(ulc(caller=>aorhash))\n");
      xlog("caller=>count $(ulc(caller=>count))\n");
      $var(i) = 0;
      while($var(i) < $(ulc(caller=>count)))
      {
        xlog("--- contact [$var(i)]\n");
        xlog("caller=>addr:       $(ulc(caller=>addr)[$var(i)])\n");
        xlog("caller=>path:       $(ulc(caller=>path)[$var(i)])\n");
        xlog("caller=>received:   $(ulc(caller=>received)[$var(i)])\n");
        xlog("caller=>expires:    $(ulc(caller=>expires)[$var(i)])\n");
        xlog("caller=>callid:     $(ulc(caller=>callid)[$var(i)])\n");
        xlog("caller=>regid:      $(ulc(caller=>regid)[$var(i)])\n");
        xlog("caller=>q:          $(ulc(caller=>q)[$var(i)])\n");
        xlog("caller=>cseq:       $(ulc(caller=>cseq)[$var(i)])\n");
        xlog("caller=>flags:      $(ulc(caller=>flags)[$var(i)])\n");
        xlog("caller=>cflags:     $(ulc(caller=>cflags)[$var(i)])\n");
        xlog("caller=>user_agent: $(ulc(caller=>user_agent)[$var(i)])\n");
        xlog("caller=>socket:     $(ulc(caller=>socket)[$var(i)])\n");
        xlog("caller=>modified:   $(ulc(caller=>modified)[$var(i)])\n");
        xlog("caller=>methods:    $(ulc(caller=>methods)[$var(i)])\n");
        $var(i) = $var(i) + 1;
      }
    }
    ...