[Fix] Use Host if IPv6 address hostname

Fix for a part of pull request #264.

websocket-sharp/Server/HttpServer.cs

@@ -157,7 +157,7 @@ namespace WebSocketSharp.Server
       if (!tryCreateUri (url, out uri, out msg))
         throw new ArgumentException (msg, "url");
 
-      var host = uri.DnsSafeHost;
+      var host = getHost (uri);
       var addr = host.ToIPAddress ();
       if (!addr.IsLocal ())
         throw new ArgumentException ("The host part isn't a local host name: " + url, "url");
@@ -638,6 +638,11 @@ namespace WebSocketSharp.Server
              : str;
     }
 
+    private static string getHost (Uri uri)
+    {
+      return uri.HostNameType == UriHostNameType.IPv6 ? uri.Host : uri.DnsSafeHost;
+    }
+
     private void init (string hostname, System.Net.IPAddress address, int port, bool secure)
     {
       _hostname = hostname ?? convertToString (address);