Enum Module
Juha Heinanen
<jh@song.fi>
Otmar Lendl
<lendl@nic.at>
Copyright © 2002, 2003 Juha Heinanen
Revision History
Revision $Revision: 6676 $ $Date: 2009-07-21 10:45:05 +0300
(Tue, 21 Jul 2009) $
__________________________________________________________
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. isn_suffix (string)
1.3.5. branchlabel (string)
1.3.6. 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. isn_query(["suffix"[,"service"]])
1.4.5. 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 isn_suffix module parameter
1.5. Setting branchlabel module parameter
1.6. Zone file example
1.7. Zone file example
1.8. Setting the bl_algorithm module parameter
1.9. enum_query usage
1.10. enum_pv_query usage
1.11. isn_query usage
1.12. 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.
In addition to standard ENUM, support for ISN (ITAD Subscriber
Numbers) is provided as well. To allow ISN lookups to resolve,
a different formatting algorithm is expected by the DNS server.
Whereas a ENUM NAPTR record expects a DNS query of the form
9.8.7.6.5.4.3.2.1.suffix, ISN method expects a DNS query of the
form 6.5.1212.suffix. That is, a valid ISN number includes a
prefix of '56' in the example. The rest of the number is a ITAD
(Internet Telephony Administrative Domain) as defined in RFCs
3872 and 2871, and as allocated by the IANA in
http://www.iana.org/assignments/trip-parameters. The ITAD is
left intact and not refersed as ENUM requires. To learn more
about ISN please refer to documents at www.freenum.org.
To complete a ISN lookup on the user part of the Request-URI,
isn_query() is used instead of enum_query().
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 OpenSIPS 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. isn_suffix (string)
The domain suffix to be used for isn_query() lookups. Can be
overridden by a parameter to isn_query.
Default value is "freenum.org."
Example 1.4. Setting isn_suffix module parameter
modparam("enum", "isn_suffix", "freenum.org.")
1.3.5. 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 1.5. Setting branchlabel module parameter
modparam("enum", "branchlabel", "i")
1.3.6. 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 1.6. 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 1.7. 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 1.8. 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 1.9. 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 1.10. 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. isn_query(["suffix"[,"service"]])
The function performs a ISN 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.
See ftp://www.ietf.org/rfc/rfc3872.txt and
ftp://www.ietf.org/rfc/rfc2871.txt for information regarding
the ITAD part of the ISN string.
Example 1.11. isn_query usage
...
# search for "e2u+sip" in freenum.org
isn_query("freenum.org.");
...
# search for "e2u+sip" in default tree (configured as parameter)
isn_query();
...
# search for "e2u+voice:sip" in freenum.org
isn_query("freenum.org.","voice");
...
1.4.5. 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 1.12. is_from_user_enum usage
...
if (is_from_user_enum()) {
....
};
...
