trackbackhandler.cs

本系统是在asp版《在线文件管理器》的基础上设计制作

//------------------------------------------------------------------------------
// <copyright company="Telligent Systems">
//     Copyright (c) Telligent Systems Corporation.  All rights reserved.
// </copyright> 
//------------------------------------------------------------------------------

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

using CommunityServer.Blogs.Components;
using CommunityServer.Components;

namespace CommunityServer.Blogs.Components
{
    /// <summary>
    /// Summary description for TrackBackHandler.
    /// </summary>
    public class TrackBackHandler : IHttpHandler
    {
        public TrackBackHandler() 
        {
        }
	
        public void ProcessRequest(HttpContext context)
        {

            context.Response.ContentType="text/xml" ;


            User user = CSContext.Current.User;
            int postId = 0 ;
            try 
            {
                postId = int.Parse(context.Request.QueryString["postid"]) ;
            }
            catch 
            {
                trackbackResponse (context, 1, "EntryID is invalid or missing" ) ;
            }


            if ( context.Request.HttpMethod == "POST" )
            {
                string title     = safeParam(context,"title") ;
                string excerpt   = safeParam(context,"excerpt") ;
                string url       = safeParam(context,"url");
                string blog_name = safeParam(context,"blog_name") ;

                // is the url valid ?
                if ( url == "" )
                {
                    trackbackResponse (context, 1, "no url parameter found, please try harder!") ;
                }
	
                string pageTitle = null;
                
                WeblogPost trackedEntry = WeblogPosts.GetPost(postId,false,true,false);

                if(trackedEntry == null)
                    trackbackResponse (context, 2, "The link does not exist" ) ;

                

                Weblog wl = trackedEntry.Section as Weblog;

                Permissions.AccessCheck(wl,Permission.View, user );

                if(!wl.EnableTrackbacks)
                    trackbackResponse (context, 2, "Trackbacks are not enabled" ) ;

				
                if (trackedEntry != null && !SourceContainsTarget(url,Globals.FullPath(BlogUrls.Instance().Post(trackedEntry,wl)), out pageTitle))
                {
                    trackbackResponse (context, 2, "Sorry couldn't find a relevant link in " + url ) ;
                }

                
                WeblogPost entry = new WeblogPost();
                entry.BlogPostType = BlogPostType.Trackback;
                entry.SectionID = wl.SectionID;
                entry.ParentID = postId;
                entry.Subject = title;
                entry.TitleUrl = url;
                entry.TrackBackName = blog_name;
                entry.Body = excerpt;
                entry.IsApproved = true;
                entry.PostDate = DateTime.Now;
                entry.BloggerTime = DateTime.Now;
                WeblogPosts.Add(entry,user);


				
            }
            else
            {

                WeblogPost entry = WeblogPosts.GetPost(postId,false,true,false);

                Weblog wl = entry.Section as Weblog;

                Permissions.AccessCheck(wl,Permission.View, user);


                XmlTextWriter w = new XmlTextWriter(context.Response.Output) ;
                w.Formatting = Formatting.Indented;


                w.WriteStartDocument() ;
                w.WriteStartElement("response") ;
                w.WriteElementString("error", "0") ;
                w.WriteStartElement("rss") ;
                w.WriteAttributeString("version", "0.91") ;
                w.WriteStartElement("channel") ;
                w.WriteElementString("title", entry.Subject ) ;
                w.WriteElementString("link", BlogUrls.Instance().TrackbackPingUrl(postId));
                w.WriteElementString("description", "" ) ;
                w.WriteElementString("language", "en-us" ) ;

                w.WriteEndElement() ; // channel
                w.WriteEndElement() ; // rss 
                w.WriteEndElement() ; // response
                w.WriteEndDocument() ;
		
            }

        }

        public bool IsReusable
        {
            get { return true; }
        }

        private void trackbackResponse(HttpContext context, int errNum, string errText)
        {
            XmlDocument d = new XmlDocument() ;
            XmlElement root = d.CreateElement("response") ;
            d.AppendChild(root) ;
            XmlElement er = d.CreateElement("error") ;
            root.AppendChild(er) ;
            er.AppendChild(d.CreateTextNode(errNum.ToString())) ;
            if ( errText != "" )
            {
                XmlElement msg = d.CreateElement("message") ;
                root.AppendChild(msg) ;
                msg.AppendChild(d.CreateTextNode(errText)) ;
            }
            d.Save ( context.Response.Output ) ;
            context.Response.End() ;
        }

        private string safeParam(HttpContext context,string pName)
        {
            if ( context.Request.Form[pName] != null )
                return Globals.HtmlEncode(context.Request.Form[pName]);
            return  string.Empty;
        }

        public static  bool SourceContainsTarget(string sURI, string tURI, out string pageTitle)
        {
            pageTitle = string.Empty ;
            string page = CSRequest.GetPageText(sURI,tURI);
            if (page == null ||  page.IndexOf(tURI) < 0 )
                return false ;
						
            string pat = @"<head.*?>.*<title.*?>(.*)</title.*?>.*</head.*?>" ;
            Regex reg = new Regex(pat, RegexOptions.IgnoreCase | RegexOptions.Singleline  ) ;
            Match m = reg.Match(page) ;
            if ( m.Success )
            {
                pageTitle = m.Result("$1") ;
                return true ;
            }
 
            return false ;
        }
    }
}