Pop3.cs :  » Bloggers » dasBlog » Lesnikowski » Pawel » Mail » Pop3 » C# / CSharp Open Source

//Pawel Lesnikowski lesnikowski@o2.pl
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;

namespace Lesnikowski.Pawel.Mail.Pop3{
  public class Pop3
  {
    // Constants
    private const string POS_STAT_IND = "+OK";
    //private const string NEG_STAT_IND = "-ERR";
    
    public string host;
    public string userName;
    public string password;
    public int port=110;
    
    private Socket socket;
        
    private int _messageCount;  // number of messages
    public int messageCount
    {
      get
      {
        return _messageCount;
      }
    }

    // constructors
    public Pop3()
    {    
      socket = null;
    }

    public void Connect()
    {
      if (host==null)
        throw new Exception("no host");

      IPHostEntry hostEntry = Dns.GetHostEntry(host);

      if (hostEntry==null)
        throw new Exception("can't get ip");
        
      // construct the endpoint
      IPEndPoint endPoint=new IPEndPoint(hostEntry.AddressList[0],port);
      
      if (endPoint==null)
        throw new Exception("can't get endpoint");
        
      // initialize socket
      socket = new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);
      
      // set the socket timeout
      //socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.SendTimeout, sendTimeout);
      //socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, receiveTimeout);
      
      socket.Connect(endPoint);
      ReceiveLine();
    }

    public void Login()
    {
      string Username = "USER " + this.userName;
      string Password = "PASS " + this.password;
      Send(Username);
      ReceiveLine();
      Send(Password);
      ReceiveLine();
    }

    public void GetAccountStat()
    {
      Send("STAT");
      string tmp=ReceiveLine();
      tmp=tmp.Substring(tmp.IndexOf(" ") + 1);
      // parse number of messages
      _messageCount = Int32.Parse(tmp.Substring(0,tmp.IndexOf(" ")).Trim());
    }

    /// <summary>
    /// Deletes message with given index when Close() is called
    /// </summary>
    public void DeleteMessage(int messageNumber) 
    {
      string command="DELE "+messageNumber.ToString();
      Send(command);
      ReceiveLine();
    }
    
    public Pop3Message GetMessageHeader(int messageNumber)
    {
      Send("TOP "+messageNumber+" 0");
      string tmp=Receive();
      //delete +OK (3 chars) and create message
      Pop3Message message=new Pop3Message(tmp.Substring(3),true);
      return message;
    }

    public Pop3Message GetMessage(int messageNumber)
    {
      Send("RETR "+messageNumber.ToString());
      string tmp=Receive();
      //delete +OK (3 chars) and create message
      Pop3Message message=new Pop3Message(tmp.Substring(3),false);
      return message;
    }


    public void Close() 
    {
      if (socket==null)
        return;
      try
      {
        Send("QUIT");
        ReceiveLine();
      }
      finally
      {
        socket.Close();
      }
    }
  
    private void Send(string command) 
    {
      // add CRLF to the message
      command+="\r\n";
  
      // convert message buffer to array of chars
      byte[] buffer=Encoding.ASCII.GetBytes(command.ToCharArray());

      // send buffer
      int bytesSent=socket.Send(buffer,buffer.Length, 0);

      if (bytesSent!=buffer.Length)
        throw new Exception("failed to send request to server");
    }

    private string ReceiveLine()
    {
      const int bufferLength=1024;
      byte[] buffer=new byte[bufferLength+1];  // extra char for null terminator
      StringBuilder message=new StringBuilder(bufferLength);
      int bytesRead;

      for(;;)
      {
        bytesRead=socket.Receive(buffer, bufferLength, 0);
        if (bytesRead==0)
          break;
        
        // add null terminator
        buffer[bytesRead]=0;
  
        // conver char array to string
        message.Append(Encoding.ASCII.GetChars(buffer, 0, bytesRead));
        if (buffer[bytesRead-1]==10)
          break;
      }
      string tmp=message.ToString();
      if(tmp.StartsWith(POS_STAT_IND)==false)
        throw new Exception("Received negative response from POP3 server");
      return tmp;
    }
    
    static bool EndsWith(StringBuilder b,string s)
    {
            int bLength=b.Length;
      int sLength=s.Length;
      if (bLength<sLength)
        return false;

      for(int i=0;i<sLength;i++)
      {
        if (s[sLength-i-1]!=b[bLength-i-1])
          return false;
      }
      return true;
    }

    private string Receive()
    {
      const int bufferLength=1024;
      byte[] buffer=new byte[bufferLength+1];  // extra char for null terminator
      StringBuilder message=new StringBuilder(bufferLength);
      int bytesRead;

      for(;;)
      {
        if (EndsWith(message,"\r\n.\r\n")==true)
        {
          //this is rather the end wait short
          if (socket.Poll(100, SelectMode.SelectRead)==false)
            break;//no data in socket
        }
        else
        {
          //it dosn't look like the end wait longer 5s
          if (socket.Poll(5000000, SelectMode.SelectRead)==false)
            break;//no data in socket
        }

        bytesRead=socket.Receive(buffer, bufferLength, 0);
        if (bytesRead==0)
          break;
        
        // add null terminator
        buffer[bytesRead]=0;

        //load with some 8bit coding to allow charset changing
        message.Append(Encoding.Default.GetChars(buffer, 0, bytesRead));
      }
      message.Replace("\n..","\n.");
      string tmp=message.ToString();

      if(tmp.StartsWith(POS_STAT_IND)==false)
        throw new Exception("Received negative response from POP3 server");

      return tmp;
  
    }

  }
}