public ClientProxyConnector(
IClientConnectorFactoryProducer clientConnectorFactoryProducer,
IOptions <ProxyOptions> proxyOptions,
ILogger logger
)
{
this.clientConnector = clientConnectorFactoryProducer.CreateClient(ConnectorFactory.TransmissionControlProtocol)
.Create();
this.proxyOptions = proxyOptions.Value;
this.logger = logger;
}
public void Connect(IPAddress ipAddress, int port)
{
if (proxyOptions == null || string.IsNullOrEmpty(proxyOptions.Server?.Trim()))
{
///Trying to read proxy from WebRequest
try
{
var proxyRequest = WebRequest.GetSystemWebProxy();
var requestedUri = new Uri($"http://{ipAddress.ToString()}");
var proxyUri = proxyRequest.GetProxy(requestedUri);
if (proxyUri == null || proxyUri == requestedUri)
{
throw new ProxyNotFoundException();
}
proxyOptions = new ProxyOptions
{
Port = proxyUri.Port,
Server = Dns.GetHostAddresses(proxyUri.Host)[0].ToString()
};
}
catch (ProxyNotFoundException)
{
proxyOptions = null;
}
catch (Exception ex)
{
this.logger.Error(ex);
proxyOptions = null;
}
}
if (proxyOptions != null)///Proxy found
{
/// Basic of Proxy Protocol
/// CONNECT: https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/CONNECT
clientConnector.Connect(IPAddress.Parse(proxyOptions.Server), proxyOptions.Port);
///Proxy Handshake Connection
var message = Encoding.ASCII.GetBytes($"CONNECT {ipAddress.ToString()}:{port} HTTP/1.1\r\n"
+ $"Connection: keep-alive\r\n\r\n");
clientConnector.Send(message, 0, message.Length);
///Receiving Proxy Response
Array.Clear(buffer, 0, buffer.Length);
clientConnector.Receive(buffer, 0, 1024);
var bufferAsString = Encoding.ASCII.GetString(buffer);
bufferAsString = bufferAsString.Replace('\0', ' ').Trim();
if (!Regex.IsMatch(bufferAsString, @"^HTTP.+200\s+Connection\s+established.*", RegexOptions.Multiline))
{
throw new ProxyConnectionException($"Connection Failed: {bufferAsString}");
}
}
else///Direct connection (PROXY NOT FOUND)
{
clientConnector.Connect(ipAddress, port);
}
}