1.1. Overview

Enum module implements enum_query function that makes an enum query based on the user part of the current request URI. The function assumes 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.".

After forming the name, enum_queryenum_query queries from DNS its NAPTR records. From the possible response the current version of enum_query chooses the FIRST record, whose flags field has string value "u" and whose services field has string value "e2u+[service:]sip" (case is ignored in both cases). "service" is given to enum_query as a parameter. If its value is "", then "e2u+sip" is looked for. If no such record is found, enum_query returns -1.

If such a record is found, enum_query checks if its regexp field is of the form !pattern!replacement!. If yes, enum_query replaces the current Request-URI with replacement, which it assumes to contain a SIP or SIPS type URI, and returns value 1.

If the regexp field is not of the form !pattern!replacement!, enum_query returns -1.

In addition to enum_query, enum module implements is_from_user_e164 function that checks if the user part of from URI is an E164 number.

TODO: In enum_query, proper implementation of the NAPTR record selection algorithm could be implemented by taking into account the order and preference fields (see draft-ietf-sipping-e164-02).

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

modparam("enum", "domain_suffix", "e1234.arpa.")

1.4. Exported Functions

...
enum_query("");
...

...
if (is_from_user_e164()) {
    ....
};
...