TrackBackNotificationProxy.cs :  » Bloggers » SubText » Subtext » Framework » Tracking » C# / CSharp Open Source

#region Disclaimer/Info

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// 
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#endregion

#region Notes

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#endregion

using System;
using System.Globalization;
using System.IO;
using System.Net;
using System.Text.RegularExpressions;
using System.Web;
using Subtext.Framework.Text;
using Subtext.Framework.Web;

namespace Subtext.Framework.Tracking{
    /// <summary>
    /// Summary description for TrackBackNotificationProxy.
    /// </summary>
    public class TrackBackNotificationProxy
    {
        public static bool TrackBackPing(string pageText, Uri url, string title, Uri link, string blogname,
                                         string description)
        {
            string trackBackItem = GetTrackBackText(pageText, url, link);
            if(trackBackItem != null)
            {
                if(!trackBackItem.ToLower(CultureInfo.InvariantCulture).StartsWith("http://"))
                {
                    trackBackItem = "http://" + trackBackItem;
                }

                string parameters = "title=" + HttpUtility.HtmlEncode(title) + "&url=" +
                                    HttpUtility.HtmlEncode(link.ToString()) + "&blog_name=" +
                                    HttpUtility.HtmlEncode(blogname) + "&excerpt=" + HttpUtility.HtmlEncode(description);

                Uri trackBackUrl = trackBackItem.ParseUri();
                if(trackBackUrl != null)
                {
                    return SendPing(trackBackUrl, parameters);
                }
            }
            return true;
        }

        private static bool SendPing(Uri trackBackItem, string parameters)
        {
            HttpWebRequest request = HttpHelper.CreateRequest(trackBackItem);
            request.Method = "POST";
            request.ContentLength = parameters.Length;
            request.ContentType = "application/x-www-form-urlencoded";
            request.KeepAlive = false;
            HttpHelper.SetProxy(request);

            using(var myWriter = new StreamWriter(request.GetRequestStream()))
            {
                myWriter.Write(parameters);
            }

            var response = (HttpWebResponse)request.GetResponse();

            return (response.StatusCode == HttpStatusCode.OK);
        }

        private static string GetTrackBackText(string pageText, Uri url, Uri postUrl)
        {
            if(!Regex.IsMatch(pageText, postUrl.ToString(), RegexOptions.IgnoreCase | RegexOptions.Singleline))
            {
                const string rdfPattern = @"<rdf:\w+\s[^>]*?>(</rdf:rdf>)?";
                var regex = new Regex(rdfPattern, RegexOptions.IgnoreCase);
                
                for(Match match = regex.Match(pageText); match.Success; match = match.NextMatch())
                {
                    if(match.Groups.ToString().Length > 0)
                    {
                        string text = match.Groups[0].ToString();
                        if(text.IndexOf(url.ToString()) > 0)
                        {
                            const string trackbackPattern = "trackback:ping=\"([^\"]+)\"";
                            var reg = new Regex(trackbackPattern, RegexOptions.IgnoreCase);
                            Match m2 = reg.Match(text);
                            if(m2.Success)
                            {
                                return m2.Result("$1");
                            }
                            return text;
                        }
                    }
                }
            }

            return null;
        }
    }
}