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NAME

Data::Validate::Domain - Domain and host name validation

VERSION

version 0.15

SYNOPSIS

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

# as a function
my $test = is_domain($suspect);
die "$test is not a domain" unless $test;

# or

die "$test is not a domain" unless is_domain($suspect, \%options);

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

die "$test is not a domain" unless $v->is_domain($suspect);

DESCRIPTION

This module offers a few subroutines for validating domain and host names.

FUNCTIONS

All of the functions below are exported by default.

All of the functions return an untainted value on success and a false value (undef or an empty list) on failure. In scalar context, you should check that the return value is defined, because something like is_domain_label('0') will return a defined but false value.

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

Note that none of these functions test whether a domain or hostname is actually resolvable or reachable.

Data::Validate::Domain->new()

This method constructs a validation object. It accepts the following arguments:

  • domain_allow_underscore

    According to RFC underscores are forbidden in hostnames but not domain names. By default is_domain(), is_domain_label(), and is_hostname() will fail if the value to be checked includes underscores. Setting this to a true value will allow the use of underscores in all functions.

  • domain_allow_single_label

    By default is_domain() will fail if you ask it to verify a domain that only has a single label i.e. "neely.cx" is good, but "com" would fail. If you set this option to a true value then is_domain() will allow single label domains through. This is most likely to be useful in combination with the domain_private_tld argument.

  • domain_disable_tld_validation

    Disables TLD validation for is_domain(). This may be useful if you need to check domains with new gTLDs that have not yet been added to Net::Domain::TLD.

  • domain_private_tld

    By default is_domain() requires all domains to have a valid public TLD (i.e. com, net, org, uk, etc). This is verified using the Net::Domain::TLD module. This behavior can be extended in two different ways. You can provide either a hash reference where additional TLDs are keys or you can supply a regular expression.

    NOTE: The TLD is normalized to the lower case form prior to the check being done. This is done only for the TLD check, and does not alter the output in any way.

    Hashref example:

      domain_private_tld => {
      privatetld1 => 1,
      privatetld2 => 1,
  }

    Regular expression example:

      domain_private_tld => qr /^(?:privatetld1|privatetld2)$/,

is_domain($domain, \%options)

This can be called as either a subroutine or a method. If called as a sub, you can pass any of the arguments accepted by the constructor as options. If called as a method, any additional options are ignored.

This returns the untainted domain name if the given $domain is a valid domain.

A dotted quad (such as 127.0.0.1) is not considered a domain and will return false. See Data::Validate::IP for IP Validation.

Per RFC 1035, this sub does accept a value ending in a single period (i.e. "domain.com.") to be a valid domain. This is called an absolute domain name, and should be properly resolved by any DNS tool (tested with dig, ssh, and Net::DNS).

  • 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_hostname($hostname, \%options)

This can be called as either a subroutine or a method. If called as a sub, you can pass any of the arguments accepted by the constructor as options. If called as a method, any additional options are ignored.

This returns the untainted hostname if the given $hostname is a valid hostname.

Hostnames are not required to end in a valid TLD.

is_domain_label($label, \%options)

This can be called as either a subroutine or a method. If called as a sub, you can pass any of the arguments accepted by the constructor as options. If called as a method, any additional options are ignored.

This returns the untainted label if the given $label is a valid label.

A domain label is simply a single piece of a domain or hostname. For example, the "www.foo.com" hostname contains the labels "www", "foo", and "com".

SEE ALSO

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

ACKNOWLEDGEMENTS

Thanks to Richard Sonnen <[email protected]> for writing the Data::Validate module.

Thanks to Len Reed <[email protected]> for helping develop the options mechanism for Data::Validate modules.

SUPPORT

Bugs may be submitted at https://github.com/houseabsolute/Data-Validate-Domain/issues.

I am also usually active on IRC as 'autarch' on irc://irc.perl.org.

SOURCE

The source code repository for Data-Validate-Domain can be found at https://github.com/houseabsolute/Data-Validate-Domain.

AUTHORS

CONTRIBUTORS

COPYRIGHT AND LICENSE

This software is copyright (c) 2021 by Neil Neely.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

The full text of the license can be found in the LICENSE file included with this distribution.