C# HttpWebRequest command to get directory listing [closed]

A few important considerations before the code:

1. The HTTP Server has to be configured to allow directories listing for the directories you want;
2. Because directory listings are normal HTML pages there is no standard that defines the format of a directory listing;
3. Due to consideration 2 you are in the land where you have to put specific code for each server.

My choice is to use regular expressions. This allows for rapid parsing and customization. You can get specific regular expressions pattern per site and that way you have a very modular approach. Use an external source for mapping URL to regular expression patterns if you plan to enhance the parsing module with new sites support without changing the source code.

Example to print directory listing from http://www.ibiblio.org/pub/

namespace Example
{
    using System;
    using System.Net;
    using System.IO;
    using System.Text.RegularExpressions;

    public class MyExample
    {
        public static string GetDirectoryListingRegexForUrl(string url)
        {
            if (url.Equals("http://www.ibiblio.org/pub/"))
            {
                return "<a href=\".*\">(?<name>.*)</a>";
            }
            throw new NotSupportedException();
        }
        public static void Main(String[] args)
        {
            string url = "http://www.ibiblio.org/pub/";
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
            using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
            {
                using (StreamReader reader = new StreamReader(response.GetResponseStream()))
                {
                    string html = reader.ReadToEnd();
                    Regex regex = new Regex(GetDirectoryListingRegexForUrl(url));
                    MatchCollection matches = regex.Matches(html);
                    if (matches.Count > 0)
                    {
                        foreach (Match match in matches)
                        {
                            if (match.Success)
                            {
                                Console.WriteLine(match.Groups["name"]);
                            }
                        }
                    }
                }
            }

            Console.ReadLine();
        }
    }
}