URLRewriter.cs :  » Bloggers » dasBlog » ProviderPortal » C# / CSharp Open Source

using System.Configuration;
using System.Diagnostics;
using System.Text.RegularExpressions;
using System.Web;
using System.Xml;

// nicked from http://www.codeproject.com/aspnet/URLRewriter.asp
namespace ProviderPortal{
  public class URLRewriter : IConfigurationSectionHandler {
    protected XmlNode _oRules = null;

    protected URLRewriter() { }

    public string GetSubstitution(string zPath) {
      Regex oReg;

      foreach (XmlNode oNode in _oRules.SelectNodes("rule")) {
        // get the url and rewrite nodes
        XmlNode oUrlNode = oNode.SelectSingleNode("url");
        XmlNode oRewriteNode = oNode.SelectSingleNode("rewrite");

        // check validity of the values
        if (oUrlNode == null || string.IsNullOrEmpty(oUrlNode.InnerText)
          || oRewriteNode == null || string.IsNullOrEmpty(oRewriteNode.InnerText)) {
          Trace.TraceWarning("Invalid urlrewrites rule discovered in web.config file.");
          continue;
        }

        oReg = new Regex(oUrlNode.InnerText, RegexOptions.IgnoreCase);

        // if match, return the substitution
        Match oMatch = oReg.Match(zPath);
        if (oMatch.Success) {
          return oReg.Replace(zPath, oRewriteNode.InnerText);
        }
      }

      return null; // no rewrite
    }

    public static void Process() {
      URLRewriter oRewriter = (URLRewriter)System.Configuration.ConfigurationManager.GetSection("urlrewrites");

      string zSubst = oRewriter.GetSubstitution(HttpContext.Current.Request.Path);

      if (!string.IsNullOrEmpty(zSubst)) {
        Trace.TraceInformation("Rewriting url '{0}' to '{1}' ", HttpContext.Current.Request.Path, zSubst);
        HttpContext.Current.RewritePath(zSubst);
      }
    }

    #region Implementation of IConfigurationSectionHandler
    public object Create(object parent, object configContext, XmlNode section) {
      _oRules = section;

      return this;
    }
    #endregion
  }
}