Data::Validate::Domain - domain validation methods

  use Data::Validate::Domain qw(is_domain);

  if(is_domain($suspect)){
        print "Looks like a domain name";
  } else {
        print "Not a domain name\n";
  }

  # or as an object
  my $v = Data::Validate::Domain->new();

  die "not a domain" unless ($v->is_domain('domain.com'));

This module collects domain validation routines to make input validation, and untainting easier and more readable.

All functions return an untainted value if the test passes, and undef if it fails. This means that you should always check for a defined status explicitly. Don't assume the return will be true. (e.g. is_username('0'))

The value to test is always the first (and often only) argument.

new - constructor for OO usage

  $obj = Data::Validate::Domain->new();

Description

Returns a Data::Validator::Domain object. This lets you access all the validator function calls as methods without importing them into your namespace or using the clumsy Data::Validate::Domain::function_name() format.

Arguments

None

Returns

Returns a Data::Validate::Domain object

is_domain - does the value look like domain name?

  is_domain($value);
  or
  $obj->is_domain($value);

Description

Returns the untainted domain name if the test value appears to be a well-formed domain name.

Arguments

$value

The potential ip to test.

Returns

Returns the untainted domain on success, undef on failure.

Notes, Exceptions, & Bugs

The function does not make any attempt to check whether a domain actually exists. It only looks to see that the format is appropriate. A dotted quad (such as 127.0.0.1) is not considered a domain and will return false. See Data::Validate::IP(3) for IP Validation.

From RFC 952

   A "name" (Net, Host, Gateway, or Domain name) is a text string up
   to 24 characters drawn from the alphabet (A-Z), digits (0-9), minus
   sign (-), and period (.).  Note that periods are only allowed when
   they serve to delimit components of "domain style names".

    No blank or space characters are permitted as part of a
   name. No distinction is made between upper and lower case.  The first
   character must be an alpha character [Relaxed in RFC 1123] .  The last 
   character must not be a minus sign or period.

From RFC 1035

    labels          63 octets or less
    names           255 octets or less

    [snip] limit the label to 63 octets or less.

    To simplify implementations, the total length of a domain name (i.e.,
    label octets and label length octets) is restricted to 255 octets or
    less.

From RFC 1123

    One aspect of host name syntax is hereby changed: the
    restriction on the first character is relaxed to allow either a
    letter or a digit.  Host software MUST support this more liberal
    syntax.

    Host software MUST handle host names of up to 63 characters and
    SHOULD handle host names of up to 255 characters.

is_domain_label - does the value look like a domain label?

  is_domain_label($value);
  or
  $obj->is_domain_label($value);

Description

Returns the untainted domain label if the test value appears to be a well-formed domain label.

Arguments

$value

The potential ip to test.

Returns

Returns the untainted domain label on success, undef on failure.

Notes, Exceptions, & Bugs

The function does not make any attempt to check whether a domain label actually exists. It only looks to see that the format is appropriate.

[RFC 1034] [RFC 1035] [RFC 2181] [RFC 1123]

Data::Validate(3)

Data::Validate::IP(3)

Neil Neely <neil@frii.net>.

Thanks to Richard Sonnen <sonnen@richardsonnen.com> for writing the Data::Validate module.

Copyright (c) 2005 Neil Neely. This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.2 or, at your option, any later version of Perl 5 you may have available.