public_suffix

A domain parser based on the Public Suffix List

public_suffix is a dart library for identifying the public suffixes (or TLDs), root domains and registrable parts of URLs.

Main features

• Identify suffix, root domain, registrable domain (root + suffix) and subdomain from URLs.
• Provide your own list of suffix rules to keep up to date with the rules you need.
• Get results from matching with only ICANN/IANA rules or also include private ones.
  • For example, a private rule can see the full github.io as suffix while ICANN only recognises the io part.
• Parse punycode encoded URLs and get both encoded and decoded results.
• Check if URLs are subdomains, have valid domain parts, or end with known suffixes.

Usage

Option 1 - Using a statically accessible list

1. Import public_suffix.dart.
2. Initialise DefaultSuffixRules from a suffix rule list.
3. Create instances of PublicSuffix to parse URLs.
4. Access the different URL components through the PublicSuffix objects.

Option 2 - Using a non-static list

1. Import public_suffix.dart.
2. Create a SuffixRules instance from a suffix rule list.
3. Create instances of PublicSuffix to parse URLs, passing in the SuffixRules instance from step 2.
4. Access the different URL components through the PublicSuffix objects.

Short example using the static list

import 'package:public_suffix/public_suffix.dart';

main() {
  // Load a list of suffix rules.
  var suffixListString = 'load the list into this string';
  DefaultSuffixRules.initFromString(suffixListString);
  
  // Parse a URL.
  var parsedUrl = PublicSuffix(urlString: 'https://www.komposten.github.io');
  
  // Obtain information using the many getters, for example:
  print(parsedUrl.suffix);      // github.io
  print(parsedUrl.root);        // komposten
  print(parsedUrl.domain);      // komposten.github.io
  print(parsedUrl.icannDomain); // github.io

  // public_suffix also supports punycoded URLs:
  parsedUrl = PublicSuffix(urlString: 'https://www.xn--6qq79v.cn');
  print(parsedUrl.domain);             // xn--6qq79v.cn
  print(parsedUrl.punyDecoded.domain); // 你好.cn
}

Obtaining a suffix list

public_suffix requires a list of suffix rules to work. There is no list bundled by default as these lists are updated frequently.

To use public_suffix you need to first load a list of rules, and then either initialise DefaultSuffixRules (for static access) or create your own instance of SuffixRules.

Initialising DefaultSuffixRules

The easiest way to use public_suffix is to get a list of rules and pass that list to DefaultSuffixRules. The PublicSuffix class will use this list by default.

There are two ways of initialising it:

1. Load the list using your own code and pass it to DefaultSuffixRules.initFromString():

   //Example using Flutter
   import 'package:flutter/services.dart';
   import 'package:public_suffix/public_suffix.dart';
   
   main() {
       var suffixList = rootBundle.loadString('assets/public_suffix_list.dat');
       DefaultSuffixRules.initFromString(suffixList);
   }

2. Import either the dart:io or the dart:html-based helper and load the list from a URI:

   //Example using dart:io; for dart:html use browser_helper.dart instead.
   import 'package:public_suffix/io_helper.dart';
   
   main() async {
     var uri = Uri.parse('https://publicsuffix.org/list/public_suffix_list.dat');
     await SuffixRulesHelper.initDefaultListFromUri(listUri);
   }

Creating SuffixRules instances

An alternative way to use public_suffix is to manually create an instance of SuffixRules and then pass that in when creating PublicSuffix objects.

Just like before, there are two ways of doing this:

1. Load the list using your own code and pass it to one of SuffixRules constructors:

   //Example using Flutter
   import 'package:flutter/services.dart';
   import 'package:public_suffix/public_suffix.dart';
   
   main() {
       var suffixList = rootBundle.loadString('assets/public_suffix_list.dat');
       var suffixRules = SuffixRules.fromString(suffixList);
   }

2. Import either the dart:io or the dart:html-based helper and load the list from a URI:

   //Example using dart:io; for dart:html use browser_helper.dart instead.
   import 'package:public_suffix/io_helper.dart';
   
   main() async {
     var uri = Uri.parse('https://publicsuffix.org/list/public_suffix_list.dat');
     var suffixRules = await SuffixRulesHelper.createListFromUri(listUri);
   }

Note: Don't overload publicsuffix.org's servers by repeatedly retrieving the suffix list from them. Cache a copy somewhere instead, and update that copy when the master copy is updated.

Utility functions

Several utility functions can be found in the DomainUtils class (imported from public_suffix.dart). These currently include:

• isSubdomainOf: Checks if a given URL is a subdomain of another domain.
• isSubdomain: Checks if a given URL has a subdomain part.
• isKnownSuffix: Checks if a given suffix (e.g. co.uk) is listed in the suffix rule list.
• hasValidDomain: Checks if a given URL contains a registrable domain part.

Most of these create PublicSuffix objects internally. If you are already working with PublicSuffix objects, there are similar methods you can call directly on those to avoid creating new ones.

Contributing

Git message conventions

public_suffix uses gitmoji to indicate commit types (bug fix, new feature, re-factor, etc.)

Commit messages should generally follow this format:

:emoji: Write a short summary on line one

Put additional information two lines down.
Use imperative forms of verbs. For example "Add", "Fix" and "Move" instead of "Added", "Fixed" and "Moved".

License

public_suffix is licensed under the MIT license. See LICENSE for the full license text.