TFTP Server

实现TFTP Server做文件传输

#region Copyright ?2005 EnerLinx.com, Inc. - All rights reserved.
/*  
 * Permission is hereby granted, free of charge, to any person obtaining a copy 
 * of this software and associated documentation files (the "Software"), to deal 
 * in the Software without restriction, including without limitation the rights 
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
 * copies of the Software, and to permit persons to whom the Software is 
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included 
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 
 * THE SOFTWARE.
 * 
 * For more information see:
 * http://www.enerlinx.com
*/
#endregion
#region History
/* $Header: /EnerLinx/Engineering/NetLinx_2/Tools/TFTPServer/TFTPServer/TFTPServer/TFTPServer.cs 3     5/17/05 8:40p Chad $ */
/*
 * $History: TFTPServer.cs $  
 * 
 * *****************  Version 3  *****************
 * User: Chad         Date: 5/17/05    Time: 8:40p
 * Updated in $/EnerLinx/Engineering/NetLinx_2/Tools/TFTPServer/TFTPServer/TFTPServer
 * checkpoint
 * 
 * *****************  Version 2  *****************
 * User: Chad         Date: 5/17/05    Time: 11:55a
 * Updated in $/EnerLinx/Engineering/NetLinx_2/Tools/TFTPServer/TFTPServer/TFTPServer
 * added MIT lic.
 * 
 * *****************  Version 1  *****************
 * User: Chad         Date: 5/17/05    Time: 11:31a
 * Created in $/EnerLinx/Engineering/NetLinx_2/Tools/TFTPServer/TFTPServer/TFTPServer
 * Initial Version
 */
#endregion

#region using
using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Text;
using System.IO;

using EnerLinxDotCom.Diagnostics;
#endregion

namespace EnerLinxDotCom.Network.Servers
{
#region TFTP Formats
// TFTP Formats
// Type   Op #     Format without header
//         2 bytes    string   1 byte     string   1 byte
//         -----------------------------------------------
// RRQ/  | 01/02 |  Filename  |   0  |    Mode    |   0  |
// WRQ    -----------------------------------------------
//         2 bytes    2 bytes       n bytes
//   ---------------------------------
// DATA  | 03    |   Block #  |    Data    |
//       ---------------------------------
//       2 bytes    2 bytes
//       -------------------
// ACK   | 04    |   Block #  |
//       --------------------
//       2 bytes  2 bytes        string    1 byte
//       ----------------------------------------
// ERROR | 05    |  ErrorCode |   ErrMsg   |   0  |
//       ----------------------------------------
#endregion

/// <summary>
/// Simple read-only TFTP Server
/// </summary>
public class TFTPServer
{
#region delegates
public delegate Stream GetFileDelegate(string filename, string mode);
#endregion

#region events
public event EventHandler ReadRequestDone;
public event EventHandler ReadBlockSent;
#endregion

#region fields
public static readonly ExTraceSwitch TFTPServerTraceSwitch = new ExTraceSwitch("TFTPServerTraceSwitch", "TFTPServer Traces." ); 

private int m_ListenPort = 69;
private UdpClient m_Server = null;
private bool m_Done = false;
private Thread m_ListenThread = null;
private GetFileDelegate m_GFD = null;
private System.IO.Stream    m_CurrentReadStream = null;
private BinaryReader m_ReadStreamReader = null;
private int                 m_CurrentBlock = 1;
private int                 m_LastBlockLength = 0;
#endregion

#region Opcode
private enum Opcodes
{
TFTP_RRQ= 01, // TFTP read request packet.
TFTP_WRQ=   02, // TFTP write request packet. 
TFTP_DATA=  03, // TFTP data packet. 
TFTP_ACK=   04, // TFTP acknowledgement packet.
TFTP_ERROR= 05, // TFTP error packet. 
TFTP_OACK=  06 // TFTP option acknowledgement packet. 
}
#endregion

#region ErrorCodes
public enum ErrorCodes
{  
TFTP_ERROR_UNDEFINED = 0, // Not defined, see error message (if any).
TFTP_ERROR_FILE_NOT_FOUND = 1, // File not found.
TFTP_ERROR_ACCESS_VIOLATION = 2,    // Access violation.
TFTP_ERROR_ALLOC_ERROR = 3, // Disk full or allocation exceeded.
TFTP_ERROR_ILLEGAL_OP = 4,    // Illegal TFTP operation.
TFTP_ERROR_UNKNOWN_TID = 5, // Unknown transfer ID.
TFTP_ERROR_FILE_EXISTS = 6,    // File already exists.
TFTP_ERROR_INVALID_USER = 7     //   No such user.
}
#endregion

#region Request Modes
public const string REQUEST_MODE_NETASCII = "netascii";
public const string REQUEST_MODE_OCTET = "octet";
public const string REQUEST_MODE_MAIL = "mail";
#endregion

#region ctor
public TFTPServer()
{
ExTrace.WriteMethodIf(TFTPServerTraceSwitch.TraceVerbose);
}
#endregion

#region GetFileHandler property
/// <summary>
/// Delegate to handle creation of file stream
/// </summary>
public GetFileDelegate GetFileHandler
{
get
{
return m_GFD;
}
set
{
m_GFD = value;
}
}
#endregion

#region Start / Stop
/// <summary>
/// Start server
/// </summary>
public void Start()
{
ExTrace.WriteMethodIf(TFTPServerTraceSwitch.TraceVerbose);

if(m_Server == null)
{
m_Server = new UdpClient(m_ListenPort);

m_ListenThread = new Thread(new ThreadStart(Listener));
m_ListenThread.Start();
}
}

/// <summary>
/// Stop server
/// </summary>
public void Stop()
{
ExTrace.WriteMethodIf(TFTPServerTraceSwitch.TraceVerbose);
m_Done = true;
try
{
if(m_Server != null)
m_Server.Close();
if(m_CurrentReadStream != null)
m_CurrentReadStream.Close();
}
catch(Exception err)
{
ExTrace.ShowException(err);
}
}
#endregion

#region Listner thread section
#region Listener thread loop
/// <summary>
/// Main listener thread loop
/// </summary>
public void Listener() 
{
ExTrace.WriteMethodIf(TFTPServerTraceSwitch.TraceVerbose);

while(!m_Done) 
{
try
{
IPEndPoint endpoint = null;
Byte[] data = m_Server.Receive(ref endpoint);

Opcodes opcode = (Opcodes)(short)((((short)data[0]) * 256) (short)data[1]);

ExTrace.WriteLineIf(TFTPServerTraceSwitch.TraceVerbose,opcode.ToString() " from " endpoint.ToString());
switch(opcode)
{
case Opcodes.TFTP_RRQ:
DoReadRequest(data, endpoint);
break;

case Opcodes.TFTP_ERROR:
DoError(data, endpoint);
break;

case Opcodes.TFTP_ACK:
DoAck(data, endpoint);
break;

case Opcodes.TFTP_WRQ:
case Opcodes.TFTP_DATA:
case Opcodes.TFTP_OACK:
default:
ExTrace.WriteLineIf(TFTPServerTraceSwitch.TraceVerbose,"Unsupported Opcode");
break;

}
}
catch(Exception err)
{
ExTrace.ShowException(err);
}
}
return;
}
#endregion

#region DoAck
/// <summary>
/// Handle ACK response and send next block.
/// </summary>
/// <param name="data">data from packet</param>
/// <param name="endpoint">client</param>
private void DoAck(Byte[] data, IPEndPoint endpoint)
{
short blocknum = (short)((((short)data[2]) * 256) (short)data[3]);
if(m_CurrentReadStream != null)
{
if(m_LastBlockLength != 4) // still more to send
{
if((blocknum 1) != this.m_CurrentBlock)
{
// not sure how we'd ever get here, but just in case
m_CurrentBlock = blocknum 1;
}
SendStream(endpoint,m_CurrentBlock);
m_CurrentBlock ;
}
}
}
#endregion

#region DoError
/// <summary>
/// Parse an error response
/// </summary>
/// <param name="data">data from packet</param>
/// <param name="endpoint">client</param>
private void DoError(Byte[] data, IPEndPoint endpoint)
{
ExTrace.WriteMethodIf(TFTPServerTraceSwitch.TraceVerbose);

Encoding    ASCII = Encoding.ASCII;

string delimStr = "\0";
char [] delimiter = delimStr.ToCharArray();

short errorcode = (short)((((short)data[2]) * 256) (short)data[3]);

string[] strData = ASCII.GetString(data,2,data.Length-2).Split(delimiter,3);

string message = strData[0];

ExTrace.WriteLineIf(TFTPServerTraceSwitch.TraceVerbose,"Error-" errorcode.ToString() ":" message);
}
#endregion

#region DoReadRequest
/// <summary>
/// Handle Read request
/// </summary>
/// <param name="data">data from packet</param>
/// <param name="endpoint">client</param>
private void DoReadRequest(Byte[] data, IPEndPoint endpoint)
{
ExTrace.WriteMethodIf(TFTPServerTraceSwitch.TraceVerbose);

Encoding    ASCII = Encoding.ASCII;

string delimStr = "\0";
char [] delimiter = delimStr.ToCharArray();

string[] strData = ASCII.GetString(data,2,data.Length-2).Split(delimiter,3);

string filename = strData[0];
string mode = strData[1].ToLower();

ExTrace.WriteLineIf(TFTPServerTraceSwitch.TraceVerbose,"filename:" filename " mode:" mode);

if(m_GFD != null)
{
ExTrace.WriteLineIf(TFTPServerTraceSwitch.TraceVerbose,"Calling GetFileDelegate...");
System.IO.Stream filestream = m_GFD(filename,mode);
ExTrace.WriteLineIf(TFTPServerTraceSwitch.TraceVerbose,"OK (filestream " ((filestream == null) ? "INVALID" : "VALID") ")");
if(filestream != null)
{
// TODO: Start a timer to close stream in connection timeout
if(m_CurrentReadStream != null)
m_CurrentReadStream.Close();
m_CurrentReadStream = filestream;
m_ReadStreamReader = new BinaryReader(m_CurrentReadStream);
m_CurrentBlock = 1;
SendStream(endpoint, m_CurrentBlock);
}
}
}
#endregion

#region SendStream
/// <summary>
/// Send part of a stream
/// </summary>
/// <param name="endpoint">location to send stream to</param>
/// <param name="BlockNumber">512 byte block to send</param>
private void SendStream(IPEndPoint endpoint, int BlockNumber)
{
ExTrace.WriteMethodIf(TFTPServerTraceSwitch.TraceSuperVerbose);

int fileoffset = (BlockNumber - 1) * 512;
m_CurrentReadStream.Seek(fileoffset,SeekOrigin.Begin);

Byte [] buffer = new Byte[516];
buffer[0] = 0;
buffer[1] = (byte)Opcodes.TFTP_DATA;
buffer[2] = (byte)((BlockNumber & 0xFF00) / 256);
buffer[3] = (byte)(BlockNumber & 0x00FF);

m_LastBlockLength = m_ReadStreamReader.Read(buffer,4,512);
m_LastBlockLength = 4;
ExTrace.WriteLineIf(TFTPServerTraceSwitch.TraceVerbose,"Sending " m_LastBlockLength.ToString() " bytes.");
int ecode = m_Server.Send(buffer, m_LastBlockLength, endpoint);

if(ecode <= 0)
ExTrace.WriteLineIf(TFTPServerTraceSwitch.TraceVerbose,"Error in send : " ecode);

if(m_LastBlockLength == 4)  // end of stream, some clients won't ACK this last packet
{
ExTrace.WriteLineIf(TFTPServerTraceSwitch.TraceVerbose,"All done, closing stream...");
m_ReadStreamReader.Close();
m_CurrentReadStream = null;
ExTrace.WriteLineIf(TFTPServerTraceSwitch.TraceVerbose,"OK.");
try
{
if(ReadRequestDone != null)
ReadRequestDone(this,null);
}
catch(Exception err)
{
ExTrace.ShowException(err);
}
}
else
{
try
{
if(ReadBlockSent != null)
ReadBlockSent(m_LastBlockLength-4, null);
}
catch(Exception err)
{
ExTrace.ShowException(err);
}
}

// TODO: Start a timer to resend in no ACK.
}
#endregion
#endregion
}
}