/BlogEngine/DotNetSlave.BusinessLogic/Ping/Pingback.cs

namespace BlogEngine.Core.Ping

{

    using System;

    using System.Net;

    using System.Text;

    using System.Xml;



    /// <summary>

    /// Sends pingbacks to website that the blog links to.

    /// </summary>

    public static class Pingback

    {

        #region Events



        /// <summary>

        ///     Occurs just before a pingback is sent.

        /// </summary>

        public static event EventHandler<EventArgs> Sending;



        /// <summary>

        ///     Occurs when a pingback has been sent

        /// </summary>

        public static event EventHandler<EventArgs> Sent;



        #endregion



        #region Public Methods



        /// <summary>

        /// Sends pingbacks to the targetUrl.

        /// </summary>

        /// <param name="sourceUrl">

        /// The source Url.

        /// </param>

        /// <param name="targetUrl">

        /// The target Url.

        /// </param>

        public static void Send(Uri sourceUrl, Uri targetUrl)

        {

            if (!BlogSettings.Instance.EnablePingBackSend)

            {

                return;

            }



            if (sourceUrl == null || targetUrl == null)

            {

                return;

            }



            try

            {

                var request = (HttpWebRequest)WebRequest.Create(targetUrl);

                request.Credentials = CredentialCache.DefaultNetworkCredentials;

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

                string pingUrl = null;



                var pingUrlKeyIndex = Array.FindIndex(

                    response.Headers.AllKeys, 

                    delegate(string k)

                        {

                            return k.Equals("x-pingback", StringComparison.OrdinalIgnoreCase) ||

                                   k.Equals("pingback", StringComparison.OrdinalIgnoreCase);

                        });



                if (pingUrlKeyIndex != -1)

                {

                    pingUrl = response.Headers[pingUrlKeyIndex];

                }



                Uri url;

                if (!string.IsNullOrEmpty(pingUrl) && Uri.TryCreate(pingUrl, UriKind.Absolute, out url))

                {

                    OnSending(url);

                    request = (HttpWebRequest)WebRequest.Create(url);

                    request.Method = "POST";



                    // request.Timeout = 10000;

                    request.ContentType = "text/xml";

                    request.ProtocolVersion = HttpVersion.Version11;

                    request.Headers["Accept-Language"] = "en-us";

                    AddXmlToRequest(sourceUrl, targetUrl, request);

                    var response2 = (HttpWebResponse)request.GetResponse();

                    response2.Close();

                    OnSent(url);

                }

            }

            catch (Exception ex)

            {

                ex = new Exception();



                // Stops unhandled exceptions that can cause the app pool to recycle

            }

        }



        #endregion



        #region Methods



        /// <summary>

        /// Adds the XML to web request. The XML is the standard

        ///     XML used by RPC-XML requests.

        /// </summary>

        /// <param name="sourceUrl">

        /// The source Url.

        /// </param>

        /// <param name="targetUrl">

        /// The target Url.

        /// </param>

        /// <param name="webreqPing">

        /// The webreq Ping.

        /// </param>

        private static void AddXmlToRequest(Uri sourceUrl, Uri targetUrl, HttpWebRequest webreqPing)

        {

            var stream = webreqPing.GetRequestStream();

            using (var writer = new XmlTextWriter(stream, Encoding.ASCII))

            {

                writer.WriteStartDocument(true);

                writer.WriteStartElement("methodCall");

                writer.WriteElementString("methodName", "pingback.ping");

                writer.WriteStartElement("params");



                writer.WriteStartElement("param");

                writer.WriteStartElement("value");

                writer.WriteElementString("string", sourceUrl.ToString());

                writer.WriteEndElement();

                writer.WriteEndElement();



                writer.WriteStartElement("param");

                writer.WriteStartElement("value");

                writer.WriteElementString("string", targetUrl.ToString());

                writer.WriteEndElement();

                writer.WriteEndElement();



                writer.WriteEndElement();

                writer.WriteEndElement();

            }

        }



        /// <summary>

        /// Called when [sending].

        /// </summary>

        /// <param name="url">The URL Uri.</param>

        private static void OnSending(Uri url)

        {

            if (Sending != null)

            {

                Sending(url, new EventArgs());

            }

        }



        /// <summary>

        /// Called when [sent].

        /// </summary>

        /// <param name="url">The URL Uri.</param>

        private static void OnSent(Uri url)

        {

            if (Sent != null)

            {

                Sent(url, new EventArgs());

            }

        }



        #endregion

    }

}