Enum Module

Juha Heinanen

   <jh@song.fi>

Otmar Lendl

   <lendl@nic.at>

   Copyright © 2002, 2003 Juha Heinanen
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies
        3. Parameters

              3.1. domain_suffix (string)
              3.2. tel_uri_params (string)
              3.3. i_enum_suffix (string)
              3.4. branchlabel (string)
              3.5. bl_algorithm (string)

        4. Functions

              4.1. enum_query(["suffix" [,"service"]])
              4.2. enum_pv_query("pvar" [,"suffix" [,"service"]])
              4.3. i_enum_query(["suffix" [,"service"]])
              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 branchlabel 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

   Table of Contents

   1. Overview
   2. Dependencies
   3. Parameters

        3.1. domain_suffix (string)
        3.2. tel_uri_params (string)
        3.3. i_enum_suffix (string)
        3.4. branchlabel (string)
        3.5. bl_algorithm (string)

   4. Functions

        4.1. enum_query(["suffix" [,"service"]])
        4.2. enum_pv_query("pvar" [,"suffix" [,"service"]])
        4.3. i_enum_query(["suffix" [,"service"]])
        4.4. is_from_user_enum()

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 Request URI 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 20. 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 enum NAPTR
   records. From the possible responses 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 the regular expression of the most preferred NAPTR record
   to 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 separated 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.

   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.

2. Dependencies

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

3. Parameters

   3.1. domain_suffix (string)
   3.2. tel_uri_params (string)
   3.3. i_enum_suffix (string)
   3.4. branchlabel (string)
   3.5. bl_algorithm (string)

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.")

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 SIP Router 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")

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.")

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 branchlabel module parameter
modparam("enum", "branchlabel", "i")

3.5. bl_algorithm (string)

   This parameter determines which algorithm the i_enum_query() function
   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 insert 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 5678 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-location-re
   cord-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.arpa
;                               )
9.9.9.8.7.6.5.i.4.3.2.1.e164.arpa. IN NAPTR "NAPTR content for  +1 234 5678 999"

   Default value is “cc”

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

4. Functions

   4.1. enum_query(["suffix" [,"service"]])
   4.2. enum_pv_query("pvar" [,"suffix" [,"service"]])
   4.3. i_enum_query(["suffix" [,"service"]])
   4.4. is_from_user_enum()

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, “Overview” for more
   information.

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

   Parameters can include pseudo-variables.

   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");
...

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

   The function performs an enum query on E.164 number stored in its first
   argument and rewrites the Request-URI with the result of the query. See
   Section 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.

   Parameters can include pseudo-variables.

   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");
...

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.

   Parameters can include pseudo-variables.

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

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()) {
        ....
};
...
