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Socks5ProxyClient.cs
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Socks5ProxyClient.cs
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/*
* Authors: Benton Stark
*
* Copyright (c) 2007-2009 Starksoft, LLC (http://www.starksoft.com)
*
* 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.
*
*/
using System;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Collections.Generic;
using System.Globalization;
using System.ComponentModel;
namespace Starksoft.Net.Proxy
{
/// <summary>
/// Socks5 connection proxy class. This class implements the Socks5 standard proxy protocol.
/// </summary>
/// <remarks>
/// This implementation supports TCP proxy connections with a Socks v5 server.
/// </remarks>
public class Socks5ProxyClient : IProxyClient
{
private string _proxyHost;
private int _proxyPort;
private string _proxyUserName;
private string _proxyPassword;
private SocksAuthentication _proxyAuthMethod;
private TcpClient _tcpClient;
private const string PROXY_NAME = "SOCKS5";
private const int SOCKS5_DEFAULT_PORT = 1080;
private const byte SOCKS5_VERSION_NUMBER = 5;
private const byte SOCKS5_RESERVED = 0x00;
private const byte SOCKS5_AUTH_METHOD_NO_AUTHENTICATION_REQUIRED = 0x00;
private const byte SOCKS5_AUTH_METHOD_GSSAPI = 0x01;
private const byte SOCKS5_AUTH_METHOD_USERNAME_PASSWORD = 0x02;
private const byte SOCKS5_AUTH_METHOD_IANA_ASSIGNED_RANGE_BEGIN = 0x03;
private const byte SOCKS5_AUTH_METHOD_IANA_ASSIGNED_RANGE_END = 0x7f;
private const byte SOCKS5_AUTH_METHOD_RESERVED_RANGE_BEGIN = 0x80;
private const byte SOCKS5_AUTH_METHOD_RESERVED_RANGE_END = 0xfe;
private const byte SOCKS5_AUTH_METHOD_REPLY_NO_ACCEPTABLE_METHODS = 0xff;
private const byte SOCKS5_CMD_CONNECT = 0x01;
private const byte SOCKS5_CMD_BIND = 0x02;
private const byte SOCKS5_CMD_UDP_ASSOCIATE = 0x03;
private const byte SOCKS5_CMD_REPLY_SUCCEEDED = 0x00;
private const byte SOCKS5_CMD_REPLY_GENERAL_SOCKS_SERVER_FAILURE = 0x01;
private const byte SOCKS5_CMD_REPLY_CONNECTION_NOT_ALLOWED_BY_RULESET = 0x02;
private const byte SOCKS5_CMD_REPLY_NETWORK_UNREACHABLE = 0x03;
private const byte SOCKS5_CMD_REPLY_HOST_UNREACHABLE = 0x04;
private const byte SOCKS5_CMD_REPLY_CONNECTION_REFUSED = 0x05;
private const byte SOCKS5_CMD_REPLY_TTL_EXPIRED = 0x06;
private const byte SOCKS5_CMD_REPLY_COMMAND_NOT_SUPPORTED = 0x07;
private const byte SOCKS5_CMD_REPLY_ADDRESS_TYPE_NOT_SUPPORTED = 0x08;
private const byte SOCKS5_ADDRTYPE_IPV4 = 0x01;
private const byte SOCKS5_ADDRTYPE_DOMAIN_NAME = 0x03;
private const byte SOCKS5_ADDRTYPE_IPV6 = 0x04;
/// <summary>
/// Authentication itemType.
/// </summary>
private enum SocksAuthentication
{
/// <summary>
/// No authentication used.
/// </summary>
None,
/// <summary>
/// Username and password authentication.
/// </summary>
UsernamePassword
}
/// <summary>
/// Create a Socks5 proxy client object.
/// </summary>
public Socks5ProxyClient() { }
/// <summary>
/// Creates a Socks5 proxy client object using the supplied TcpClient object connection.
/// </summary>
/// <param name="tcpClient">A TcpClient connection object.</param>
public Socks5ProxyClient(TcpClient tcpClient)
{
if (tcpClient == null)
throw new ArgumentNullException("tcpClient");
_tcpClient = tcpClient;
}
/// <summary>
/// Create a Socks5 proxy client object. The default proxy port 1080 is used.
/// </summary>
/// <param name="proxyHost">Host name or IP address of the proxy server.</param>
public Socks5ProxyClient(string proxyHost)
{
if (String.IsNullOrEmpty(proxyHost))
throw new ArgumentNullException("proxyHost");
_proxyHost = proxyHost;
_proxyPort = SOCKS5_DEFAULT_PORT;
}
/// <summary>
/// Create a Socks5 proxy client object.
/// </summary>
/// <param name="proxyHost">Host name or IP address of the proxy server.</param>
/// <param name="proxyPort">Port used to connect to proxy server.</param>
public Socks5ProxyClient(string proxyHost, int proxyPort)
{
if (String.IsNullOrEmpty(proxyHost))
throw new ArgumentNullException("proxyHost");
if (proxyPort <= 0 || proxyPort > 65535)
throw new ArgumentOutOfRangeException("proxyPort", "port must be greater than zero and less than 65535");
_proxyHost = proxyHost;
_proxyPort = proxyPort;
}
/// <summary>
/// Create a Socks5 proxy client object. The default proxy port 1080 is used.
/// </summary>
/// <param name="proxyHost">Host name or IP address of the proxy server.</param>
/// <param name="proxyUserName">Proxy authentication user name.</param>
/// <param name="proxyPassword">Proxy authentication password.</param>
public Socks5ProxyClient(string proxyHost, string proxyUserName, string proxyPassword)
{
if (String.IsNullOrEmpty(proxyHost))
throw new ArgumentNullException("proxyHost");
if (proxyUserName == null)
throw new ArgumentNullException("proxyUserName");
if (proxyPassword == null)
throw new ArgumentNullException("proxyPassword");
_proxyHost = proxyHost;
_proxyPort = SOCKS5_DEFAULT_PORT;
_proxyUserName = proxyUserName;
_proxyPassword = proxyPassword;
}
/// <summary>
/// Create a Socks5 proxy client object.
/// </summary>
/// <param name="proxyHost">Host name or IP address of the proxy server.</param>
/// <param name="proxyPort">Port used to connect to proxy server.</param>
/// <param name="proxyUserName">Proxy authentication user name.</param>
/// <param name="proxyPassword">Proxy authentication password.</param>
public Socks5ProxyClient(string proxyHost, int proxyPort, string proxyUserName, string proxyPassword)
{
if (String.IsNullOrEmpty(proxyHost))
throw new ArgumentNullException("proxyHost");
if (proxyPort <= 0 || proxyPort > 65535)
throw new ArgumentOutOfRangeException("proxyPort", "port must be greater than zero and less than 65535");
if (proxyUserName == null)
throw new ArgumentNullException("proxyUserName");
if (proxyPassword == null)
throw new ArgumentNullException("proxyPassword");
_proxyHost = proxyHost;
_proxyPort = proxyPort;
_proxyUserName = proxyUserName;
_proxyPassword = proxyPassword;
}
/// <summary>
/// Gets or sets host name or IP address of the proxy server.
/// </summary>
public string ProxyHost
{
get { return _proxyHost; }
set { _proxyHost = value; }
}
/// <summary>
/// Gets or sets port used to connect to proxy server.
/// </summary>
public int ProxyPort
{
get { return _proxyPort; }
set { _proxyPort = value; }
}
/// <summary>
/// Gets String representing the name of the proxy.
/// </summary>
/// <remarks>This property will always return the value 'SOCKS5'</remarks>
public string ProxyName
{
get { return PROXY_NAME; }
}
/// <summary>
/// Gets or sets proxy authentication user name.
/// </summary>
public string ProxyUserName
{
get { return _proxyUserName; }
set { _proxyUserName = value; }
}
/// <summary>
/// Gets or sets proxy authentication password.
/// </summary>
public string ProxyPassword
{
get { return _proxyPassword; }
set { _proxyPassword = value; }
}
/// <summary>
/// Gets or sets the TcpClient object.
/// This property can be set prior to executing CreateConnection to use an existing TcpClient connection.
/// </summary>
public TcpClient TcpClient
{
get { return _tcpClient; }
set { _tcpClient = value; }
}
/// <summary>
/// Creates a remote TCP connection through a proxy server to the destination host on the destination port.
/// </summary>
/// <param name="destinationHost">Destination host name or IP address of the destination server.</param>
/// <param name="destinationPort">Port number to connect to on the destination host.</param>
/// <returns>
/// Returns an open TcpClient object that can be used normally to communicate
/// with the destination server
/// </returns>
/// <remarks>
/// This method creates a connection to the proxy server and instructs the proxy server
/// to make a pass through connection to the specified destination host on the specified
/// port.
/// </remarks>
public TcpClient CreateConnection(string destinationHost, int destinationPort)
{
if (String.IsNullOrEmpty(destinationHost))
throw new ArgumentNullException("destinationHost");
if (destinationPort <= 0 || destinationPort > 65535)
throw new ArgumentOutOfRangeException("destinationPort", "port must be greater than zero and less than 65535");
try
{
// if we have no connection, create one
if (_tcpClient == null)
{
if (String.IsNullOrEmpty(_proxyHost))
throw new ProxyException("ProxyHost property must contain a value.");
if (_proxyPort <= 0 || _proxyPort > 65535)
throw new ProxyException("ProxyPort value must be greater than zero and less than 65535");
// create new tcp client object to the proxy server
_tcpClient = new TcpClient();
// attempt to open the connection
_tcpClient.Connect(_proxyHost, _proxyPort);
}
// determine which authentication method the client would like to use
DetermineClientAuthMethod();
// negotiate which authentication methods are supported / accepted by the server
NegotiateServerAuthMethod();
// send a connect command to the proxy server for destination host and port
SendCommand(SOCKS5_CMD_CONNECT, destinationHost, destinationPort);
// return the open proxied tcp client object to the caller for normal use
return _tcpClient;
}
catch (Exception ex)
{
throw new ProxyException(String.Format(CultureInfo.InvariantCulture, "Connection to proxy host {0} on port {1} failed.", Utils.GetHost(_tcpClient), Utils.GetPort(_tcpClient)), ex);
}
}
private void DetermineClientAuthMethod()
{
// set the authentication itemType used based on values inputed by the user
if (_proxyUserName != null && _proxyPassword != null)
_proxyAuthMethod = SocksAuthentication.UsernamePassword;
else
_proxyAuthMethod = SocksAuthentication.None;
}
private void NegotiateServerAuthMethod()
{
// get a reference to the network stream
NetworkStream stream = _tcpClient.GetStream();
// SERVER AUTHENTICATION REQUEST
// The client connects to the server, and sends a version
// identifier/method selection message:
//
// +----+----------+----------+
// |VER | NMETHODS | METHODS |
// +----+----------+----------+
// | 1 | 1 | 1 to 255 |
// +----+----------+----------+
var haveUserPass = !String.IsNullOrEmpty(_proxyUserName) &&
!String.IsNullOrEmpty(_proxyPassword);
var authRequest = new List<byte>();
authRequest.Add(SOCKS5_VERSION_NUMBER);
if (haveUserPass) {
authRequest.Add(2);
authRequest.Add(SOCKS5_AUTH_METHOD_NO_AUTHENTICATION_REQUIRED);
authRequest.Add(SOCKS5_AUTH_METHOD_USERNAME_PASSWORD);
} else {
authRequest.Add(1);
authRequest.Add(SOCKS5_AUTH_METHOD_NO_AUTHENTICATION_REQUIRED);
}
// send the request to the server specifying authentication types supported by the client.
stream.Write(authRequest.ToArray(), 0, authRequest.Count);
// SERVER AUTHENTICATION RESPONSE
// The server selects from one of the methods given in METHODS, and
// sends a METHOD selection message:
//
// +----+--------+
// |VER | METHOD |
// +----+--------+
// | 1 | 1 |
// +----+--------+
//
// If the selected METHOD is X'FF', none of the methods listed by the
// client are acceptable, and the client MUST close the connection.
//
// The values currently defined for METHOD are:
// * X'00' NO AUTHENTICATION REQUIRED
// * X'01' GSSAPI
// * X'02' USERNAME/PASSWORD
// * X'03' to X'7F' IANA ASSIGNED
// * X'80' to X'FE' RESERVED FOR PRIVATE METHODS
// * X'FF' NO ACCEPTABLE METHODS
// receive the server response
byte[] response = new byte[2];
stream.Read(response, 0, response.Length);
// the first byte contains the socks version number (e.g. 5)
// the second byte contains the auth method acceptable to the proxy server
byte acceptedAuthMethod = response[1];
// if the server does not accept any of our supported authenication methods then throw an error
if (acceptedAuthMethod == SOCKS5_AUTH_METHOD_REPLY_NO_ACCEPTABLE_METHODS)
{
_tcpClient.Close();
throw new ProxyException("The proxy destination does not accept the supported proxy client authentication methods.");
}
// if the server accepts a username and password authentication and none is provided by the user then throw an error
if (acceptedAuthMethod == SOCKS5_AUTH_METHOD_USERNAME_PASSWORD && _proxyAuthMethod == SocksAuthentication.None)
{
_tcpClient.Close();
throw new ProxyException("The proxy destination requires a username and password for authentication.");
}
if (acceptedAuthMethod == SOCKS5_AUTH_METHOD_USERNAME_PASSWORD)
{
// USERNAME / PASSWORD SERVER REQUEST
// Once the SOCKS V5 server has started, and the client has selected the
// Username/Password Authentication protocol, the Username/Password
// subnegotiation begins. This begins with the client producing a
// Username/Password request:
//
// +----+------+----------+------+----------+
// |VER | ULEN | UNAME | PLEN | PASSWD |
// +----+------+----------+------+----------+
// | 1 | 1 | 1 to 255 | 1 | 1 to 255 |
// +----+------+----------+------+----------+
byte[] credentials = new byte[_proxyUserName.Length + _proxyPassword.Length + 3];
credentials[0] = 1;
credentials[1] = (byte)_proxyUserName.Length;
Array.Copy(ASCIIEncoding.ASCII.GetBytes(_proxyUserName), 0, credentials, 2, _proxyUserName.Length);
credentials[_proxyUserName.Length + 2] = (byte)_proxyPassword.Length;
Array.Copy(ASCIIEncoding.ASCII.GetBytes(_proxyPassword), 0, credentials, _proxyUserName.Length + 3, _proxyPassword.Length);
// USERNAME / PASSWORD SERVER RESPONSE
// The server verifies the supplied UNAME and PASSWD, and sends the
// following response:
//
// +----+--------+
// |VER | STATUS |
// +----+--------+
// | 1 | 1 |
// +----+--------+
//
// A STATUS field of X'00' indicates success. If the server returns a
// `failure' (STATUS value other than X'00') status, it MUST close the
// connection.
stream.Write(credentials, 0, credentials.Length);
byte[] crResponse = new byte[2];
stream.Read(crResponse, 0, crResponse.Length);
if (crResponse[1] != 0)
{
_tcpClient.Close();
throw new ProxyException("Proxy authentification failure!");
}
}
}
private byte GetDestAddressType(string host)
{
IPAddress ipAddr = null;
bool result = IPAddress.TryParse(host, out ipAddr);
if (!result)
return SOCKS5_ADDRTYPE_DOMAIN_NAME;
switch (ipAddr.AddressFamily)
{
case AddressFamily.InterNetwork:
return SOCKS5_ADDRTYPE_IPV4;
case AddressFamily.InterNetworkV6:
return SOCKS5_ADDRTYPE_IPV6;
default:
throw new ProxyException(String.Format(CultureInfo.InvariantCulture, "The host addess {0} of type '{1}' is not a supported address type. The supported types are InterNetwork and InterNetworkV6.", host, Enum.GetName(typeof(AddressFamily), ipAddr.AddressFamily)));
}
}
private byte[] GetDestAddressBytes(byte addressType, string host)
{
switch (addressType)
{
case SOCKS5_ADDRTYPE_IPV4:
case SOCKS5_ADDRTYPE_IPV6:
return IPAddress.Parse(host).GetAddressBytes();
case SOCKS5_ADDRTYPE_DOMAIN_NAME:
// create a byte array to hold the host name bytes plus one byte to store the length
byte[] bytes = new byte[host.Length + 1];
// if the address field contains a fully-qualified domain name. The first
// octet of the address field contains the number of octets of name that
// follow, there is no terminating NUL octet.
bytes[0] = Convert.ToByte(host.Length);
Encoding.ASCII.GetBytes(host).CopyTo(bytes, 1);
return bytes;
default:
return null;
}
}
private byte[] GetDestPortBytes(int value)
{
byte[] array = new byte[2];
array[0] = Convert.ToByte(value / 256);
array[1] = Convert.ToByte(value % 256);
return array;
}
private void SendCommand(byte command, string destinationHost, int destinationPort)
{
NetworkStream stream = _tcpClient.GetStream();
byte addressType = GetDestAddressType(destinationHost);
byte[] destAddr = GetDestAddressBytes(addressType, destinationHost);
byte[] destPort = GetDestPortBytes(destinationPort);
// The connection request is made up of 6 bytes plus the
// length of the variable address byte array
//
// +----+-----+-------+------+----------+----------+
// |VER | CMD | RSV | ATYP | DST.ADDR | DST.PORT |
// +----+-----+-------+------+----------+----------+
// | 1 | 1 | X'00' | 1 | Variable | 2 |
// +----+-----+-------+------+----------+----------+
//
// * VER protocol version: X'05'
// * CMD
// * CONNECT X'01'
// * BIND X'02'
// * UDP ASSOCIATE X'03'
// * RSV RESERVED
// * ATYP address itemType of following address
// * IP V4 address: X'01'
// * DOMAINNAME: X'03'
// * IP V6 address: X'04'
// * DST.ADDR desired destination address
// * DST.PORT desired destination port in network octet order
byte[] request = new byte[4 + destAddr.Length + 2];
request[0] = SOCKS5_VERSION_NUMBER;
request[1] = command;
request[2] = SOCKS5_RESERVED;
request[3] = addressType;
destAddr.CopyTo(request, 4);
destPort.CopyTo(request, 4 + destAddr.Length);
// send connect request.
stream.Write(request, 0, request.Length);
// PROXY SERVER RESPONSE
// +----+-----+-------+------+----------+----------+
// |VER | REP | RSV | ATYP | BND.ADDR | BND.PORT |
// +----+-----+-------+------+----------+----------+
// | 1 | 1 | X'00' | 1 | Variable | 2 |
// +----+-----+-------+------+----------+----------+
//
// * VER protocol version: X'05'
// * REP Reply field:
// * X'00' succeeded
// * X'01' general SOCKS server failure
// * X'02' connection not allowed by ruleset
// * X'03' Network unreachable
// * X'04' Host unreachable
// * X'05' Connection refused
// * X'06' TTL expired
// * X'07' Command not supported
// * X'08' Address itemType not supported
// * X'09' to X'FF' unassigned
//* RSV RESERVED
//* ATYP address itemType of following address
byte[] response = new byte[255];
// read proxy server response
var responseSize = stream.Read(response, 0, response.Length);
byte replyCode = response[1];
// evaluate the reply code for an error condition
if (responseSize < 2 || replyCode != SOCKS5_CMD_REPLY_SUCCEEDED)
HandleProxyCommandError(response, destinationHost, destinationPort );
}
private void HandleProxyCommandError(byte[] response, string destinationHost, int destinationPort)
{
string proxyErrorText;
byte replyCode = response[1];
byte addrType = response[3];
string addr = "";
Int16 port = 0;
switch (addrType)
{
case SOCKS5_ADDRTYPE_DOMAIN_NAME:
int addrLen = Convert.ToInt32(response[4]);
byte[] addrBytes = new byte[addrLen];
for (int i = 0; i < addrLen; i++)
addrBytes[i] = response[i + 5];
addr = System.Text.ASCIIEncoding.ASCII.GetString(addrBytes);
byte[] portBytesDomain = new byte[2];
portBytesDomain[0] = response[6 + addrLen];
portBytesDomain[1] = response[5 + addrLen];
port = BitConverter.ToInt16(portBytesDomain, 0);
break;
case SOCKS5_ADDRTYPE_IPV4:
byte[] ipv4Bytes = new byte[4];
for (int i = 0; i < 4; i++)
ipv4Bytes[i] = response[i + 4];
IPAddress ipv4 = new IPAddress(ipv4Bytes);
addr = ipv4.ToString();
byte[] portBytesIpv4 = new byte[2];
portBytesIpv4[0] = response[9];
portBytesIpv4[1] = response[8];
port = BitConverter.ToInt16(portBytesIpv4, 0);
break;
case SOCKS5_ADDRTYPE_IPV6:
byte[] ipv6Bytes = new byte[16];
for (int i = 0; i < 16; i++)
ipv6Bytes[i] = response[i + 4];
IPAddress ipv6 = new IPAddress(ipv6Bytes);
addr = ipv6.ToString();
byte[] portBytesIpv6 = new byte[2];
portBytesIpv6[0] = response[21];
portBytesIpv6[1] = response[20];
port = BitConverter.ToInt16(portBytesIpv6, 0);
break;
}
switch (replyCode)
{
case SOCKS5_CMD_REPLY_GENERAL_SOCKS_SERVER_FAILURE:
proxyErrorText = "a general socks destination failure occurred";
break;
case SOCKS5_CMD_REPLY_CONNECTION_NOT_ALLOWED_BY_RULESET:
proxyErrorText = "the connection is not allowed by proxy destination rule set";
break;
case SOCKS5_CMD_REPLY_NETWORK_UNREACHABLE:
proxyErrorText = "the network was unreachable";
break;
case SOCKS5_CMD_REPLY_HOST_UNREACHABLE:
proxyErrorText = "the host was unreachable";
break;
case SOCKS5_CMD_REPLY_CONNECTION_REFUSED:
proxyErrorText = "the connection was refused by the remote network";
break;
case SOCKS5_CMD_REPLY_TTL_EXPIRED:
proxyErrorText = "the time to live (TTL) has expired";
break;
case SOCKS5_CMD_REPLY_COMMAND_NOT_SUPPORTED:
proxyErrorText = "the command issued by the proxy client is not supported by the proxy destination";
break;
case SOCKS5_CMD_REPLY_ADDRESS_TYPE_NOT_SUPPORTED:
proxyErrorText = "the address type specified is not supported";
break;
default:
proxyErrorText = String.Format(CultureInfo.InvariantCulture, "that an unknown reply with the code value '{0}' was received by the destination", replyCode.ToString(CultureInfo.InvariantCulture));
break;
}
string exceptionMsg = String.Format(CultureInfo.InvariantCulture, "The {0} concerning destination host {1} port number {2}. The destination reported the host as {3} port {4}.", proxyErrorText, destinationHost, destinationPort, addr, port.ToString(CultureInfo.InvariantCulture));
throw new ProxyException(exceptionMsg);
}
#region "Async Methods"
private BackgroundWorker _asyncWorker;
private Exception _asyncException;
bool _asyncCancelled;
/// <summary>
/// Gets a value indicating whether an asynchronous operation is running.
/// </summary>
/// <remarks>Returns true if an asynchronous operation is running; otherwise, false.
/// </remarks>
public bool IsBusy
{
get { return _asyncWorker == null ? false : _asyncWorker.IsBusy; }
}
/// <summary>
/// Gets a value indicating whether an asynchronous operation is cancelled.
/// </summary>
/// <remarks>Returns true if an asynchronous operation is cancelled; otherwise, false.
/// </remarks>
public bool IsAsyncCancelled
{
get { return _asyncCancelled; }
}
/// <summary>
/// Cancels any asychronous operation that is currently active.
/// </summary>
public void CancelAsync()
{
if (_asyncWorker != null && !_asyncWorker.CancellationPending && _asyncWorker.IsBusy)
{
_asyncCancelled = true;
_asyncWorker.CancelAsync();
}
}
private void CreateAsyncWorker()
{
if (_asyncWorker != null)
_asyncWorker.Dispose();
_asyncException = null;
_asyncWorker = null;
_asyncCancelled = false;
_asyncWorker = new BackgroundWorker();
}
/// <summary>
/// Event handler for CreateConnectionAsync method completed.
/// </summary>
public event EventHandler<CreateConnectionAsyncCompletedEventArgs> CreateConnectionAsyncCompleted;
/// <summary>
/// Asynchronously creates a remote TCP connection through a proxy server to the destination host on the destination port.
/// </summary>
/// <param name="destinationHost">Destination host name or IP address.</param>
/// <param name="destinationPort">Port number to connect to on the destination host.</param>
/// <returns>
/// Returns TcpClient object that can be used normally to communicate
/// with the destination server.
/// </returns>
/// <remarks>
/// This method instructs the proxy server
/// to make a pass through connection to the specified destination host on the specified
/// port.
/// </remarks>
public void CreateConnectionAsync(string destinationHost, int destinationPort)
{
if (_asyncWorker != null && _asyncWorker.IsBusy)
throw new InvalidOperationException("The Socks4 object is already busy executing another asynchronous operation. You can only execute one asychronous method at a time.");
CreateAsyncWorker();
_asyncWorker.WorkerSupportsCancellation = true;
_asyncWorker.DoWork += new DoWorkEventHandler(CreateConnectionAsync_DoWork);
_asyncWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(CreateConnectionAsync_RunWorkerCompleted);
Object[] args = new Object[2];
args[0] = destinationHost;
args[1] = destinationPort;
_asyncWorker.RunWorkerAsync(args);
}
private void CreateConnectionAsync_DoWork(object sender, DoWorkEventArgs e)
{
try
{
Object[] args = (Object[])e.Argument;
e.Result = CreateConnection((string)args[0], (int)args[1]);
}
catch (Exception ex)
{
_asyncException = ex;
}
}
private void CreateConnectionAsync_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (CreateConnectionAsyncCompleted != null)
CreateConnectionAsyncCompleted(this, new CreateConnectionAsyncCompletedEventArgs(_asyncException, _asyncCancelled, (TcpClient)e.Result));
}
#endregion
}
}