---
name: "Domain::PublicSuffix"
section: "3pm"
platform: "linux"
package: "libdomain-publicsuffix-perl"
version: "0.21-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Domain::PublicSuffix"
---

# Domain::PublicSuffix(3pm)

Parse a domain down to root

## NAME

Domain::PublicSuffix - Parse a domain down to root

## SYNOPSIS

```
 use Domain::PublicSuffix;
 my $suffix = Domain::PublicSuffix->new({
   'data_file' => '/tmp/effective_tld_names.dat'
 });
 my $root = $suffix->get_root_domain('www.google.com');
 # $root now contains "google.com"
 $root = $suffix->get_root_domain('www.google.co.uk');
 # $root now contains google.co.uk
 my $suf = $suffix->suffix();
 # $suf now contains co.uk
 my $tld = $suffix->tld();
 # $tld now contains uk
```

## DESCRIPTION

This module utilizes the "effective\_tld\_names.dat" provided by Mozilla as a way to effectively reduce a fully qualified domain name down to the absolute root. The Mozilla PublicSuffix file is an open source, fully documented format that shows absolute root TLDs, primarily for Mozilla's browser products to be able to determine how far a cookie's security boundaries go.

This module will attempt to search etc directories in /usr/share/publicsuffix, /usr, /usr/local, and /opt/local for the effective\_tld\_names.dat file. If a file is not found, a default file is loaded from Domain::PublicSuffix::Default, which is current at the time of the module's release. You can override the data file path by giving the **new()** method a 'data\_file' argument.

When creating a new PublicSuffix object, the module will load the data file as specified, and use the internal structure to parse each domain sent to the get\_root\_domain method. To re-parse the file, you must destroy and create a new object, or execute the \_parse\_data\_file method directly, though that is not recommended.

## PUBLIC ACCESSORS

- **error()**

  On unsuccessful parse, contains a human-readable error string.

- **suffix()**

  Returns the effective tld of the last parsed domain. For the domain 'google.co.uk', this would return 'co.uk'.

- **tld()**

  Returns the true DNS tld of the last parsed domain. For the domain 'google.co.uk', this would return 'uk'.

## PUBLIC METHODS

- new(\\%arguments)

  Instantiate a PublicSuffix object. It is best to instantiate an object and continue calling get\_root\_domain instead of continually recreating the object, as the data file is read and parsed on instantiation.

  Can take a hashref of arguments:

  - data\_file

    A fully qualified path, to override the effective\_tld\_names.dat file.

  - use\_default

    Use the provided publicsuffix file, do not search for any other files.

  - domain\_allow\_underscore

    A flag to indicate that underscores should be allowed in hostnames (contra to the RFCs). Default: undef.

  - allow\_unlisted\_tld

    A flag to indicate that unlisted TLDs should be passed through. This follows the spec as listed on publicsuffix.org, but is not how this module works by default, or before 0.16. Default: undef

- get\_root\_domain( $domain )

  Given a fully qualified domain name, return the parsed root domain name. Returns undefined if an error occurs parsing the given domain, and fills the error accessor with a human-readable error string.

## SEE ALSO

- •

  GitHub

  \<http://www.github.com/nmelnick/Domain-PublicSuffix\>

- •

  Current List:

  \<http://mxr.mozilla.org/mozilla-central/source/netwerk/dns/effective\_tld\_names.dat?raw=1\> \[mxr.mozilla.org\]

- •

  Mozilla Documentation:

  \<http://wiki.mozilla.org/Gecko:TLD\_Service\>

- •

  Public Info Site:

  \<http://publicsuffix.org/\>

## BUGS

Please report any bugs or feature requests to `"bug-domain-publicsuffix at rt.cpan.org"`, or through the web interface at \<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Domain-PublicSuffix\>. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

## SUPPORT

You can find documentation for this module with the perldoc command.

```
  perldoc Domain::PublicSuffix
```

You can also look for information at:

- •

  RT: CPAN's request tracker

  \<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Domain-PublicSuffix\>

- •

  AnnoCPAN: Annotated CPAN documentation

  \<http://annocpan.org/dist/Domain-PublicSuffix\>

- •

  CPAN Ratings

  \<http://cpanratings.perl.org/d/Domain-PublicSuffix\>

- •

  Search CPAN

  \<http://search.cpan.org/dist/Domain-PublicSuffix\>

## CONTRIBUTORS

dkg: Daniel Kahn Gillmor

gavinc: Gavin Carr

jwieland: Jason Wieland

## COPYRIGHT & LICENSE

Copyright 2008-2020 Nicholas Melnick, `"nick at abstractwankery.com"`.

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