Enum Module

Juha Heinanen

   <jh@song.fi>

Otmar Lendl

   <lendl@nic.at>

   Copyright © 2002, 2003 Juha Heinanen
   Revision History
   Revision $Revision: 4630 $ $Date: 2008-03-08 00:03:56 +0100
                              (Sa, 08 MÃ¤r 2008) $
     __________________________________________________________

   Table of Contents

   1. Admin Guide

        1.1. Overview
        1.2. Dependencies
        1.3. Exported Parameters

              1.3.1. domain_suffix (string)
              1.3.2. tel_uri_params (string)
              1.3.3. i_enum_suffix (string)
              1.3.4. branchlabel (string)
              1.3.5. bl_algorithm (string)

        1.4. Exported Functions

              1.4.1. enum_query(["suffix"[,"service"]])
              1.4.2. enum_pv_query("pvar"[,"suffix"[,"service"]])
              1.4.3. i_enum_query(["suffix"[,"service"]])
              1.4.4. is_from_user_enum()

   List of Examples

   1.1. Setting domain_suffix module parameter
   1.2. Setting tel_uri_params module parameter
   1.3. Setting i_enum_suffix module parameter
   1.4. Setting brachlabel module parameter
   1.5. Zone file example
   1.6. Zone file example
   1.7. Setting the bl_algorithm module parameter
   1.8. enum_query usage
   1.9. enum_pv_query usage
   1.10. is_from_user_enum usage

Chapter 1. Admin Guide

1.1. Overview

   Enum module implements [i_]enum_query functions that make an
   enum query based on the user part of the current Request-URI.
   These functions assume that the user part consists of an
   international phone number of the form +decimal-digits, where
   the number of digits is at least 2 and at most 15. Out of this
   number enum_query forms a domain name, where the digits are in
   reverse order and separated by dots followed by domain suffix
   that by default is "e164.arpa.". For example, if the user part
   is +35831234567, the domain name will be
   "7.6.5.4.3.2.1.3.8.5.3.e164.arpa.". i_enum_query operates in a
   similar fashion. The only difference is that it adds a label
   (default "i") to branch off from the default, user-ENUM tree to
   an infrastructure ENUM tree.

   After forming the domain name, enum_query queries DNS for its
   NAPTR records. From the possible response enum_query chooses
   those records, whose flags field has string value "u", and
   whose services field has string value "e2u+[service:]sip" or
   "e2u+type[:subtype][+type[:subtype]...]" (case is ignored in
   both cases), and whose regexp field is of the form
   !pattern!replacement!.

   Then enum_query sorts the chosen NAPTR records based on their
   <order, preference>. After sorting, enum_query replaces the
   current Request URI by applying regexp of the most preferred
   NAPTR record its user part and appends to the request new
   branches by applying regexp of each remaining NAPTR record to
   the user part of the current Request URI. If a new URI is a tel
   URI, enum_query appends to it as tel URI parameters the value
   of tel_uri_params module parameter. Finally, enum_query
   associates a q value with each new URI based on the <order,
   preference> of the corresponding NAPTR record.

   When using enum_query without any parameters, it searches for
   NAPTRs with service type "e2u+sip" in the default enum tree.
   When using enum_query with a single parameter, this parameter
   will be used as enum tree. When using enum_query with two
   parameters, the functionality depends on the first letter in
   the second parameter. When the first letter is not a '+' sign,
   the second parameter will be used to search for NAPTRs with
   service type "e2u+parameter:sip". When the second parameter
   starts with a '+' sign, the ENUM lookup also supports compound
   NAPTRs (e.g. "e2u+voice:sip+video:sip") and searching for
   multiple service types within one lookup. Multiple service
   types must be separeted by a '+' sign.

   Most of the time you want to route based on the RURI. On rare
   occasions you may wish to route based on something else. The
   function enum_pv_query mimics the behavior of the enum_query
   function except the E.164 number in its pseudo variable
   argument is used for the enum lookup instead of the user part
   of the RURI. Obviously the user part of the RURI is still used
   in the NAPTR regexp.

   Enum query returns 1 if the current Request URI was replaced
   and -1 if not.

   Enum module also implements is_from_user_enum function. This
   function does an enum lookup on the from user and returns true
   if found, false otherwise.

1.2. Dependencies

   The module depends on the following modules (in the other words
   the listed modules must be loaded before this module):
     * No dependencies.

1.3. Exported Parameters

1.3.1. domain_suffix (string)

   The domain suffix to be added to the domain name obtained from
   the digits of an E164 number. Can be overridden by a parameter
   to enum_query.

   Default value is "e164.arpa."

   Example 1.1. Setting domain_suffix module parameter
modparam("enum", "domain_suffix", "e1234.arpa.")

1.3.2. tel_uri_params (string)

   A string whose contents is appended to each new tel URI in the
   request as tel URI parameters.

Note

   Currently Kamailio does not support tel URIs. This means that
   at present tel_uri_params is appended as URI parameters to
   every URI.

   Default value is ""

   Example 1.2. Setting tel_uri_params module parameter
modparam("enum", "tel_uri_params", ";npdi")

1.3.3. i_enum_suffix (string)

   The domain suffix to be used for i_enum_query() lookups. Can be
   overridden by a parameter to i_enum_query.

   Default value is "e164.arpa."

   Example 1.3. Setting i_enum_suffix module parameter
modparam("enum", "i_enum_suffix", "e1234.arpa.")

1.3.4. branchlabel (string)

   This parameter determines which label i_enum_query() will use
   to branch off to the infrastructure ENUM tree.

   Default value is ""i""

   Example 1.4. Setting brachlabel module parameter
modparam("enum", "branchlabel", "i")

1.3.5. bl_algorithm (string)

   This parameter determines which algorithm i_enum_query() will
   use to select the position in the DNS tree where the
   infrastructure tree branches off the user ENUM tree.

   If set to "cc", i_enum_query() will always inserts the label at
   the country-code level. Examples: i.1.e164.arpa,
   i.3.4.e164.arpa, i.2.5.3.e164.arpa

   If set to "txt", i_enum_query() will look for a TXT record at
   [branchlabel].[reverse-country-code].[i_enum_suffix] to
   indicate after how many digits the label should in inserted.

   Example 1.5. Zone file example
i.1.e164.arpa.                     IN TXT   "4"
9.9.9.8.7.6.5.i.4.3.2.1.e164.arpa. IN NAPTR "NAPTR content for  +1 234 5
678 999"

   If set to "ebl", i_enum_query() will look for an EBL (ENUM
   Branch Label) record at
   [branchlabel].[reverse-country-code].[i_enum_suffix]. See
   http://www.ietf.org/internet-drafts/draft-lendl-enum-branch-loc
   ation-record-00.txt for a description of that record and the
   meaning of the fields. The RR type for the EBL has not been
   allocated yet. This version of the code uses 65300. See
   resolve.h.

   Example 1.6. Zone file example
i.1.e164.arpa.     TYPE65300  \# 14 (
                              04    ; position
                              01 69 ; separator
                              04 65 31 36 34 04 61 72 70 61 00 ; e164.ar
pa
;                               )
9.9.9.8.7.6.5.i.4.3.2.1.e164.arpa. IN NAPTR "NAPTR content for  +1 234 5
678 999"

   Default value is "cc"

   Example 1.7. Setting the bl_algorithm module parameter
modparam("enum", "bl_algorithm", "txt")

1.4. Exported Functions

1.4.1.  enum_query(["suffix"[,"service"]])

   The function performs an enum query and rewrites the
   Request-URI with the result of the query. See Section 1.1,
   "Overview" for more information.

   Meaning of the parameters is as follows:
     * suffix - Suffix to be appended to the domain name.
     * service - Service string to be used in the service field.

   This function can be used from REQUEST_ROUTE.

   Example 1.8. enum_query usage
...
# search for "e2u+sip" in freenum.org
enum_query("freenum.org.");
...
# search for "e2u+sip" in default tree (configured as parameter)
enum_query();
...
# search for "e2u+voice:sip" in e164.arpa
enum_query("e164.arpa.","voice");
...
# search for service type "sip" or "voice:sip" or "video:sip"
# note the '+' sign in front of the second parameter
enum_query("e164.arpa.","+sip+voice:sip+video:sip");
...
# quering for service sip and voice:sip
enum_query("e164.arpa.");
enum_query("e164.arpa.","voice");
# or use instead
enum_query("e164.arpa.","+sip+voice:sip");
...

1.4.2.  enum_pv_query("pvar"[,"suffix"[,"service"]])

   The function performs an enum query on E.164 number stored in
   its pseudo variable argument and rewrites the Request-URI with
   the result of the query. See Section 1.1, "Overview" for more
   information.

   Meaning of the parameters is as follows:
     * pvar - Pseudo variable that holds an E.164 number on which
       enum query is performed.
     * suffix - Suffix to be appended to the domain name.
     * service - Service string to be used in the service field.

   This function can be used from REQUEST_ROUTE.

   Example 1.9. enum_pv_query usage
...
# search for "e2u+sip" in freenum.org
enum_pv_query("$avp(i:100)", "freenum.org.");
...
# search for "e2u+sip" in default tree (configured as parameter)
enum_pv_query("$fU");
...
# search for "e2u+voice:sip" in e164.arpa
enum_pv_query("$avp(i:100)","e164.arpa.","voice");
...
# search for service type "sip" or "voice:sip" or "video:sip"
# note the '+' sign in front of the second parameter
enum_pv_query("$fU","e164.arpa.","+sip+voice:sip+video:sip");
...
# quering for service sip and voice:sip
enum_pv_query("$avp(i:100)","e164.arpa.");
enum_pv_query("$avp(i:100)","e164.arpa.","voice");
# or use instead
enum_pv_query("$avp(i:100)","e164.arpa.","+sip+voice:sip");
...

1.4.3.  i_enum_query(["suffix"[,"service"]])

   The function performs an enum query and rewrites the
   Request-URI with the result of the query. This the
   Infrastructure-ENUM version of enum_query(). The only
   difference to enum_query() is in the calculation of the FQDN
   where NAPTR records are looked for.

   See
   ftp://ftp.rfc-editor.org/in-notes/internet-drafts/draft-haberle
   r-carrier-enum-01.txt for the rationale behind this function.

1.4.4. is_from_user_enum()

   Checks if the user part of from URI is found in an enum lookup.
   Returns 1 if yes and -1 if not.

   This function can be used from REQUEST_ROUTE.

   Example 1.10. is_from_user_enum usage
...
if (is_from_user_enum()) {
        ....
};
...
