Virtual site handler in .net

I cam across a situation the other day where I found that my ASP.NET was limited to 1 website and I wanted to be able to host more than one website. Each site wasn't going to be that big or clever so I decided to see if I could come up with an IHttpModule which would be able to make it serve different pages depending on which domain was requested.

The core of the solution I came up with is the VirtualSiteManager class which given a request will return a re-written path which an IHttpModule can rewrite to.

public class VirtualSiteManager
{
   public VirtualSiteManager(string defaultSiteName)
   {
       _defaultSiteName = defaultSiteName;
       Sites = new Dictionary<string, VirtualSite>();
   }

   private string _defaultSiteName;
  
   private static VirtualSiteManager _instance;
   private static Type _lock = typeof(VirtualSiteManager);

   public static VirtualSiteManager Instance
   {
       get
       {
           lock (_lock)
           {
               if (_instance == null)
               {
                   _instance = (VirtualSiteManager) WebConfigurationManager.GetSection("virtualSite");
               }
           }

           return _instance;
       }
   }

   public VirtualSite DefaultSite
   {
       get
       {
           VirtualSite defaultSite = null;

           if (Sites.ContainsKey(_defaultSiteName))
           {
               defaultSite = Sites[_defaultSiteName];
           }

           return defaultSite;
       }
   }

   public Dictionary<string, VirtualSite> Sites
   {
       get;
       private set;
   }

   public void AddSite(VirtualSite site)
   {
       if (!Sites.ContainsKey(site.Host))
       {
           Sites.Add(site.Host, site);
       }
       else
       {
           Sites[site.Host] = site;
       }
   }

   public void AddSite(string name, string host, string virtualPath)
   {
       AddSite(new VirtualSite(name, host, virtualPath));
   }

   public string RewritePath(HttpContext context)
   {
       string host = context.Request.Url.Host;
       VirtualSite handlingSite = (Sites.ContainsKey(host)) ? Sites[host]: DefaultSite;
       string currentPath = context.Request.CurrentExecutionFilePath;

       context.Response.AddHeader("X-Debug-currentPath", currentPath);

       string returnPath = handlingSite.VirtualPath + (currentPath.StartsWith("/") ? currentPath.Substring(1) : currentPath);

       if (returnPath.EndsWith("/"))
       {
           returnPath += "index.aspx";
       }

       return returnPath;
   }
}

I store the domains and what their virtual path's are in the Web.Config like this:

<configSections>
<section name="virtualSite" type="RomfordEvan.Web.Components.VirtualSite.VirtualSiteHandler, RomfordEvan.Web.Components"/>
</configSections>
<virtualSite default="default">
<site name="default" host="www.domain1.com" virtualPath="/"/>
<site name="localhost" host="localhost" virtualPath="/"/>
<site name="domain2" host="www.domain2.com" virtualPath="/domain2/"/>
</virtualSite>

The IConfigurationSectionHandler to read the Web.Config and create the VirtualSiteManager looks like this:

public class VirtualSiteHandler : IConfigurationSectionHandler
{
   #region IConfigurationSectionHandler Members

   public object Create(object parent, object configContext, System.Xml.XmlNode section)
   {           
       XmlAttribute def = section.Attributes["default"];
      
       string defaultSiteName = string.Empty;

       if (def != null && def.InnerText.Length > 0)
       {
           defaultSiteName = def.InnerText;
       }

       VirtualSiteManager manager = new VirtualSiteManager(defaultSiteName);

       XmlNodeList siteNodes = section.SelectNodes(".//site");

       foreach (XmlNode siteNode in siteNodes)
       {
           manager.AddSite(siteNode.Attributes["name"].InnerText, siteNode.Attributes["host"].InnerText, siteNode.Attributes["virtualPath"].InnerText);
       }

       return manager;
   }

   #endregion
}

This works fine with the following caveats:

• Under IIS6 it requires wildcard mapping to the ASP.NET ISAPI filter.
• You will need to add HttpHandlers for all the file types which your site will serve (see below)

<add verb="GET,POST" path="*/" validate="true" type="System.Web.UI.PageHandlerFactory" />
<add verb="GET" path="*.html" validate="true" type="System.Web.StaticFileHandler" />
<add verb="GET" path="*.js" validate="true" type="System.Web.StaticFileHandler" />
<add verb="GET" path="*.gif" validate="true" type="System.Web.StaticFileHandler" />
<add verb="GET" path="*.jpg" validate="true" type="System.Web.StaticFileHandler" />
<add verb="GET" path="*.png" validate="true" type="System.Web.StaticFileHandler" />
<add verb="GET" path="*.css" validate="true" type="System.Web.StaticFileHandler" />