nntpclient.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.IO;
using System.Net;
using System.Threading;
using System.Net.Sockets;
using System.Collections;

namespace AspNetForums.Components {

    public class NntpClient {
    
        private TcpClient       connection = null;
        private Stream          stream = null;
        private StreamReader    reader = null;
        private StreamWriter    writer = null;


        public NntpClient(String nntpHost) {

            // Attempt to resolve the host name
            //
            if (Dns.GetHostByName(nntpHost) == null)
                throw new Exception("Host: " + nntpHost + " does not exist or cannot be reached"); 

            // Create a new tcp connection to the specified host
            //
            connection = new TcpClient(nntpHost, 119);

            // Get a handle to the open TCP stream
            //
            this.stream = connection.GetStream();

            // Get stream reader and writer
            //
            this.reader = new StreamReader(stream);
            this.writer = new StreamWriter(stream);

            String header = reader.ReadLine();

        }


        private NntpResponse SendCommand(NntpCommand command) {

            return SendCommand(command, null);

        }

        private NntpResponse SendCommand(NntpCommand command, string commandParameters) {

#if DEBUG
            Console.WriteLine("NNTP Send Command: " + command.ToString() + " " + commandParameters);
#endif

            switch (command) {

                case NntpCommand.Body:
                    WriteLine("body " + commandParameters);
                    break;

                case NntpCommand.EndOfText:
                    WriteLine(".");
                    break;

                case NntpCommand.Group:
                    WriteLine("group " + commandParameters);
                    break;

                case NntpCommand.Head:
                    WriteLine("head " + commandParameters);
                    break;

                case NntpCommand.List:
                    WriteLine("list " + commandParameters);
                    break;

                case NntpCommand.Post:
                    WriteLine("post " + commandParameters);
                    break;

                case NntpCommand.Xhdr:
                    WriteLine("xhdr " + commandParameters);
                    break;

            }

            String response = reader.ReadLine();

#if DEBUG
            Console.WriteLine(response);
#endif

            // Create the response class to return
            //
            ResponseCode responseCode = (ResponseCode) Int32.Parse(response.Substring(0, 3));
            NntpResponse nntpResponse = new NntpResponse(responseCode, response);

            return nntpResponse; 
        }


        private void WriteLine(String line) {

            writer.Write(line + "\r\n");
            writer.Flush();
        }

        private NntpGroup ChangeGroup(string groupName) {

            NntpGroup nntpGroup;

            // Execute the NNTP change group command
            //
            NntpResponse nntpResponse = SendCommand(NntpCommand.Group, groupName);

            // Ensure we got back the expected response
            //
            if (nntpResponse.ResponseCode != ResponseCode.GroupSelected) {

                throw new Exception("Group: " + groupName + " does not exist on server");

            }

            // Parse out information about the group
            //
            nntpGroup = new NntpGroup(nntpResponse.RawResponse);

            return nntpGroup;

        }

        public String [] GetGroups() {

            ArrayList newsgroups = new ArrayList();

            ResponseCode responseCode = SendCommand(NntpCommand.List).ResponseCode;

            if (responseCode != ResponseCode.ListOfNewsGroupsFollows) {

                throw new Exception("Error Obtaining Newsgroup List");

            }

            String responseLine = null;

            while ((responseLine = reader.ReadLine()) != ".") {
                newsgroups.Add( responseLine.Substring(0, responseLine.IndexOf(' ')) );
            }

            return (String []) newsgroups.ToArray(typeof(String));
        }

        public String [] GetArticleIDs(String group, int startPostNumber, int maxBackArticles) {
            ArrayList articles = new ArrayList();

            // Change to the requested group
            //
            NntpGroup nntpGroup = ChangeGroup(group);

            // Ensure we're not getting back more articles then we want
            //
            if ( (nntpGroup.EndPostNumber - startPostNumber) > maxBackArticles )
                startPostNumber = nntpGroup.EndPostNumber - maxBackArticles;

            // Request a set of articles
            //
            ResponseCode responseCode = SendCommand(NntpCommand.Xhdr, "message-id " + startPostNumber + "-").ResponseCode;

            // Handle error codes
            //
            if (responseCode == ResponseCode.NoSuchArticleFound) {
                return new String[0];
            } else if (responseCode != ResponseCode.ArticleRetrievedHeadFollows) {
                throw new Exception("Error Obtaining Newsgroup Articles");
            }

            String responseLine = null;

#if DEBUG
            Console.WriteLine("Reading articles...");
#endif

            while ((responseLine = reader.ReadLine()) != ".")
                articles.Add( responseLine ); 

            return (String []) articles.ToArray(typeof(String));
        }

        // need to get the references header to 
        public Hashtable GetArticleHeaders(String articleID) {

            Hashtable headers = new Hashtable();

            ResponseCode responseCode = SendCommand(NntpCommand.Head, articleID).ResponseCode;

            if (responseCode != ResponseCode.ArticleRetrievedHeadFollows) {
                throw new Exception("Error Obtaining Article Header: " + articleID);
            }

            String responseLine = null;

            while ((responseLine = reader.ReadLine()) != ".") {

                int token = responseLine.IndexOf(":");

                if (token != -1) {
                    headers[responseLine.Substring(0, token).ToLower()] = responseLine.Substring(token+1);
                }
            }

            return headers;
        }

        public String GetArticleBody(String articleID) {

            String body = "";

            ResponseCode responseCode = SendCommand(NntpCommand.Body, articleID).ResponseCode;

            if (responseCode != ResponseCode.ArticleRetrievedBodyFollows) {
                throw new Exception("Error Obtaining Article Body: " + articleID);
            }

            String responseLine = null;

            while ((responseLine = reader.ReadLine()) != ".") {

                body += responseLine + "\r\n";
            }

            return body;
        }

        public NntpPost GetArticle(String articleID) {

            return new NntpPost(articleID, GetArticleHeaders(articleID), GetArticleBody(articleID));
        }

        public void PostArticle(NntpPost post) {

            ResponseCode responseCode = SendCommand(NntpCommand.Post).ResponseCode;

            if (responseCode != ResponseCode.SendArticleToPost) {
                throw new Exception("Error Posting Article!");
            }

            foreach (DictionaryEntry header in post.Headers) {
                WriteLine(header.Key + ": " + header.Value);
            }

            WriteLine("");

            WriteLine(post.Body);
            
            responseCode = SendCommand(NntpCommand.EndOfText).ResponseCode;

            if (responseCode != ResponseCode.ArticlePostedOk) {
                throw new Exception("Error Completing the Posting of an Article!");
            }

#if DEBUG
            foreach(DictionaryEntry header in post.Headers) {
                Console.WriteLine(header.Key + ":" + header.Value);
            }
#endif
        }

        public void Close() {

            reader.Close();
            writer.Close();
            stream.Close();
            connection.Close();
        }

    }
}