Public Suffix List C# parser

Question

Does anyone have Public Suffix List (getting real domain) parser in c#.

It was available on code.google.com /p/domainname-parser/ (remove space before p in name) , however project has probably been removed from google code, since I cannot access project folders and source anymore.

Answer 1

Was just looking for this myself, it seems to still be available -

https://github.com/tinohager/Nager.PublicSuffix

Answer 2

I couldn't get the code in gary's answer to pass the mozilla test cases, so hacked these mods together based on the original and the algorithm described here. Hopefully it's of use to someone if the domainname-parser code dissapears from the web.

namespace DomainName.Parser
{
  using System.Collections.Generic;
  using System.Linq;
  using System;

  public class DomainName
  {
    public DomainName(string rawDomainName, string publicSuffix, string registerableDomainName)
    {
      this.RawDomainName = rawDomainName;
      this.PublicSuffix = publicSuffix;
      this.RegisterableDomainName = registerableDomainName;
    }

    public string RawDomainName { get; private set; }

    public string PublicSuffix { get; private set; }

    public string RegisterableDomainName { get; private set; }

    public static bool TryParse(string rawDomainName, PublicSuffixRuleCache ruleCache, out DomainName domainName)
    {
      if (string.IsNullOrEmpty(rawDomainName) || !rawDomainName.Contains('.') || rawDomainName.StartsWith("."))
      {
        domainName = new DomainName(rawDomainName, null, null);
        return true;
      }

      try
      {
        rawDomainName = rawDomainName.ToLower();

        //  Split our domain into parts (based on the '.')
        //  We'll be checking rules from the right-most part of the domain
        var domainLabels = rawDomainName.Trim().Split('.').ToList();
        domainLabels.Reverse();

        // If no rules match, the prevailing rule is "*"
        var prevailingRule = FindMatchingRule(domainLabels, ruleCache) ?? new PublicSuffixRule("*");

        // If the prevailing rule is an exception rule, modify it by removing the leftmost label.
        if (prevailingRule.Type == PublicSuffixRule.RuleType.Exception)
        {
          var labels = prevailingRule.Labels;
          labels.Reverse();
          labels.RemoveAt(0);

          prevailingRule = new PublicSuffixRule(string.Join(".", labels));
        }

        // The public suffix is the set of labels from the domain which directly match the labels of the prevailing rule (joined by dots).
        var publicSuffix = Enumerable.Range(0, prevailingRule.Labels.Count).Aggregate(string.Empty, (current, i) => string.Format("{0}.{1}", domainLabels[i], current).Trim('.'));

        // The registered or registrable domain is the public suffix plus one additional label.        
        var registrableDomain = string.Format("{0}.{1}", domainLabels[prevailingRule.Labels.Count], publicSuffix);

        domainName = new DomainName(rawDomainName, publicSuffix, registrableDomain);
        return true;
      }
      catch
      {
        domainName = null;
        return false;
      }      
    }

    private static PublicSuffixRule FindMatchingRule(List<string> domainLabels, PublicSuffixRuleCache ruleCache)
    {
      var ruleMatches = ruleCache.PublicSuffixRules.Where(r => r.AppliesTo(domainLabels)).ToList();

      // If there is only one match, return it.
      if (ruleMatches.Count() == 1)
      {
        return ruleMatches[0];
      }

      // If more than one rule matches, the prevailing rule is the one which is an exception rule.
      var exceptionRules = ruleMatches.Where(r => r.Type == PublicSuffixRule.RuleType.Exception).ToList();
      if (exceptionRules.Count() == 1)
      {
        return exceptionRules[0];
      }      
      if (exceptionRules.Count() > 1)
      {
        throw new ApplicationException("Unexpectedly found multiple matching exception rules.");
      }

      // If there is no matching exception rule, the prevailing rule is the one with the most labels.
      var prevailingRule = ruleMatches.OrderByDescending(r => r.Labels.Count).Take(1).SingleOrDefault();
      return prevailingRule;
    }
  }

  public class PublicSuffixRule
  {
    /// <summary>
    /// Construct a rule based on a single line from the www.publicsuffix.org list
    /// </summary>
    /// <param name="ruleLine">The rule line.</param>       
    public PublicSuffixRule(string ruleLine)
    {
      if (string.IsNullOrEmpty(ruleLine) || string.IsNullOrWhiteSpace(ruleLine))
      {
        throw new ArgumentNullException("ruleLine");
      }

      //  Parse the rule and set properties accordingly:
      string ruleName;

      if (ruleLine.StartsWith("*", StringComparison.InvariantCultureIgnoreCase))
      {
        this.Type = RuleType.Wildcard;
        ruleName = ruleLine;
      }
      else if (ruleLine.StartsWith("!", StringComparison.InvariantCultureIgnoreCase))
      {
        this.Type = RuleType.Exception;
        ruleName = ruleLine.Substring(1);
      }
      else
      {
        this.Type = RuleType.Normal;
        ruleName = ruleLine;
      }

      this.Name = ruleName.Split(' ')[0];

      var labels = this.Name.Split('.').ToList();
      labels.Reverse();

      this.Labels = labels;
    }

    public string Name { get; private set; }

    public RuleType Type { get; private set; }

    public List<string> Labels { get; private set; }

    public bool AppliesTo(List<string> domainLabels)
    {
      if (this.Labels.Count > domainLabels.Count)
      {
        return false;
      }

      foreach (var position in Enumerable.Range(0, this.Labels.Count))
      {
        if (this.Labels[position] == "*")
        {
          return true;
        }

        if (this.Labels[position] != domainLabels[position])
        {
          return false;
        }
      }

      return true;
    }

    /// <summary>
    /// Rule type
    /// </summary>
    public enum RuleType
    {
      /// <summary>
      /// A normal rule
      /// </summary>
      Normal,

      /// <summary>
      /// A wildcard rule, as defined by www.publicsuffix.org
      /// </summary>
      Wildcard,

      /// <summary>
      /// An exception rule, as defined by www.publicsuffix.org
      /// </summary>
      Exception
    }
  }

  public class PublicSuffixRuleCache
  {
    public PublicSuffixRuleCache(string publicSuffixRulesFileLocation)
    {
      if (string.IsNullOrEmpty(publicSuffixRulesFileLocation))
      {
        throw new ArgumentNullException("publicSuffixRulesFileLocation");
      }

      this.PublicSuffixRules = GetRules(publicSuffixRulesFileLocation);
    }

    public PublicSuffixRuleCache(IEnumerable<string> publicSuffixRules)
    {
      this.PublicSuffixRules = GetRules(publicSuffixRules);
    }

    public List<PublicSuffixRule> PublicSuffixRules { get; private set; }

    /// <summary>
    /// Gets the list of TLD rules from the cache
    /// </summary>
    /// <returns></returns>
    private static List<PublicSuffixRule> GetRules(string publicSuffixRulesFileLocation)
    {
      var results = new List<PublicSuffixRule>();

      //  If the cached suffix rules file exists...
      if (File.Exists(publicSuffixRulesFileLocation))
      {
        //  Load the rules from the cached text file
        var ruleStrings = File.ReadAllLines(publicSuffixRulesFileLocation, Encoding.UTF8).ToList();
        results = GetRules(ruleStrings);
      }

      return results;
    }

    private static List<PublicSuffixRule> GetRules(IEnumerable<string> publicSuffixRules)
    {
      // Strip out any lines that are a comment or blank.         
      return
        publicSuffixRules.Where(
          ruleString =>
            ruleString.Trim().Length != 0
            && !ruleString.StartsWith("//", StringComparison.InvariantCultureIgnoreCase)).Select(ruleString => new PublicSuffixRule(ruleString)).ToList();             
    }
  }  
}

Unit tests:

namespace DomainName.Library.Tests
{
  using FluentAssertions;

  using Xunit;

  using DomainName.Parser;

  public class CheckPublicSuffixTest2
  {
    public bool CheckRegisterableDomain(string domainName, string registerableDomain)
    {
      var ruleCache = new PublicSuffixRuleCache(@"C:\publicsuffix.txt");

      DomainName outDomain;
      if (DomainName.TryParse(domainName, ruleCache, out outDomain))
      {
        return outDomain.RegisterableDomainName == registerableDomain;
      }

      return registerableDomain == null;
    }

    [Fact]
    public void TestCheckPublicSuffix()
    {
      // Any copyright is dedicated to the Public Domain.
      // http://creativecommons.org/publicdomain/zero/1.0/

      // null input.
      this.CheckRegisterableDomain(null, null).Should().BeTrue();

      // Mixed case.
      this.CheckRegisterableDomain("COM", null).Should().BeTrue();
      this.CheckRegisterableDomain("example.COM", "example.com").Should().BeTrue();
      this.CheckRegisterableDomain("WwW.example.COM", "example.com").Should().BeTrue();

      // Leading dot.
      this.CheckRegisterableDomain(".com", null).Should().BeTrue();
      this.CheckRegisterableDomain(".example", null).Should().BeTrue();
      this.CheckRegisterableDomain(".example.com", null).Should().BeTrue();
      this.CheckRegisterableDomain(".example.example", null).Should().BeTrue();

      // Unlisted TLD.
      this.CheckRegisterableDomain("example", null).Should().BeTrue();
      this.CheckRegisterableDomain("example.example", "example.example").Should().BeTrue();
      this.CheckRegisterableDomain("b.example.example", "example.example").Should().BeTrue();
      this.CheckRegisterableDomain("a.b.example.example", "example.example").Should().BeTrue();

      // TLD with only 1 rule.
      this.CheckRegisterableDomain("biz", null).Should().BeTrue();
      this.CheckRegisterableDomain("domain.biz", "domain.biz").Should().BeTrue();
      this.CheckRegisterableDomain("b.domain.biz", "domain.biz").Should().BeTrue();
      this.CheckRegisterableDomain("a.b.domain.biz", "domain.biz").Should().BeTrue();

      // TLD with some 2-level rules.
      this.CheckRegisterableDomain("com", null).Should().BeTrue();
      this.CheckRegisterableDomain("example.com", "example.com").Should().BeTrue();
      this.CheckRegisterableDomain("b.example.com", "example.com").Should().BeTrue();
      this.CheckRegisterableDomain("a.b.example.com", "example.com").Should().BeTrue();
      this.CheckRegisterableDomain("uk.com", null).Should().BeTrue();
      this.CheckRegisterableDomain("example.uk.com", "example.uk.com").Should().BeTrue();
      this.CheckRegisterableDomain("b.example.uk.com", "example.uk.com").Should().BeTrue();
      this.CheckRegisterableDomain("a.b.example.uk.com", "example.uk.com").Should().BeTrue();
      this.CheckRegisterableDomain("test.ac", "test.ac").Should().BeTrue();

      // TLD with only 1 (wildcard) rule.
      this.CheckRegisterableDomain("cy", null).Should().BeTrue();
      this.CheckRegisterableDomain("c.cy", null).Should().BeTrue();
      this.CheckRegisterableDomain("b.c.cy", "b.c.cy").Should().BeTrue();
      this.CheckRegisterableDomain("a.b.c.cy", "b.c.cy").Should().BeTrue();

      // More complex TLD.
      this.CheckRegisterableDomain("jp", null).Should().BeTrue();
      this.CheckRegisterableDomain("test.jp", "test.jp").Should().BeTrue();
      this.CheckRegisterableDomain("www.test.jp", "test.jp").Should().BeTrue();
      this.CheckRegisterableDomain("ac.jp", null).Should().BeTrue();
      this.CheckRegisterableDomain("test.ac.jp", "test.ac.jp").Should().BeTrue();
      this.CheckRegisterableDomain("www.test.ac.jp", "test.ac.jp").Should().BeTrue();
      this.CheckRegisterableDomain("kyoto.jp", null).Should().BeTrue();
      this.CheckRegisterableDomain("test.kyoto.jp", "test.kyoto.jp").Should().BeTrue();
      this.CheckRegisterableDomain("ide.kyoto.jp", null).Should().BeTrue();
      this.CheckRegisterableDomain("b.ide.kyoto.jp", "b.ide.kyoto.jp").Should().BeTrue();
      this.CheckRegisterableDomain("a.b.ide.kyoto.jp", "b.ide.kyoto.jp").Should().BeTrue();
      this.CheckRegisterableDomain("c.kobe.jp", null).Should().BeTrue();
      this.CheckRegisterableDomain("b.c.kobe.jp", "b.c.kobe.jp").Should().BeTrue();
      this.CheckRegisterableDomain("a.b.c.kobe.jp", "b.c.kobe.jp").Should().BeTrue();
      this.CheckRegisterableDomain("city.kobe.jp", "city.kobe.jp").Should().BeTrue();
      this.CheckRegisterableDomain("www.city.kobe.jp", "city.kobe.jp").Should().BeTrue();

      // TLD with a wildcard rule and exceptions.
      this.CheckRegisterableDomain("om", null).Should().BeTrue();
      this.CheckRegisterableDomain("test.om", null).Should().BeTrue();
      this.CheckRegisterableDomain("b.test.om", "b.test.om").Should().BeTrue();
      this.CheckRegisterableDomain("a.b.test.om", "b.test.om").Should().BeTrue();
      this.CheckRegisterableDomain("songfest.om", "songfest.om").Should().BeTrue();
      this.CheckRegisterableDomain("www.songfest.om", "songfest.om").Should().BeTrue();

      // US K12.
      this.CheckRegisterableDomain("us", null).Should().BeTrue();
      this.CheckRegisterableDomain("test.us", "test.us").Should().BeTrue();
      this.CheckRegisterableDomain("www.test.us", "test.us").Should().BeTrue();
      this.CheckRegisterableDomain("ak.us", null).Should().BeTrue();
      this.CheckRegisterableDomain("test.ak.us", "test.ak.us").Should().BeTrue();
      this.CheckRegisterableDomain("www.test.ak.us", "test.ak.us").Should().BeTrue();
      this.CheckRegisterableDomain("k12.ak.us", null).Should().BeTrue();
      this.CheckRegisterableDomain("test.k12.ak.us", "test.k12.ak.us").Should().BeTrue();
      this.CheckRegisterableDomain("www.test.k12.ak.us", "test.k12.ak.us").Should().BeTrue();
    }
  }
}