/// <summary>
/// This is called when client is aware of proxy
/// So for HTTPS requests client would send CONNECT header to negotiate a secure tcp tunnel via proxy
/// </summary>
/// <param name="endPoint"></param>
/// <param name="tcpClient"></param>
/// <returns></returns>
private async Task HandleClient(ExplicitProxyEndPoint endPoint, TcpClient tcpClient)
{
bool disposed = false;
var clientStream = new CustomBufferedStream(tcpClient.GetStream(), BufferSize);
var clientStreamReader = new CustomBinaryReader(clientStream, BufferSize);
var clientStreamWriter = new HttpResponseWriter(clientStream);
Uri httpRemoteUri;
try
{
//read the first line HTTP command
string httpCmd = await clientStreamReader.ReadLineAsync();
if (string.IsNullOrEmpty(httpCmd))
{
return;
}
string httpMethod;
string httpUrl;
Version version;
Request.ParseRequestLine(httpCmd, out httpMethod, out httpUrl, out version);
httpRemoteUri = httpMethod == "CONNECT" ? new Uri("http://" + httpUrl) : new Uri(httpUrl);
//filter out excluded host names
bool excluded = false;
if (endPoint.ExcludedHttpsHostNameRegex != null)
{
excluded = endPoint.ExcludedHttpsHostNameRegexList.Any(x => x.IsMatch(httpRemoteUri.Host));
}
if (endPoint.IncludedHttpsHostNameRegex != null)
{
excluded = !endPoint.IncludedHttpsHostNameRegexList.Any(x => x.IsMatch(httpRemoteUri.Host));
}
ConnectRequest connectRequest = null;
//Client wants to create a secure tcp tunnel (probably its a HTTPS or Websocket request)
if (httpMethod == "CONNECT")
{
connectRequest = new ConnectRequest
{
RequestUri = httpRemoteUri,
OriginalRequestUrl = httpUrl,
HttpVersion = version,
Method = httpMethod,
};
await HeaderParser.ReadHeaders(clientStreamReader, connectRequest.RequestHeaders);
var connectArgs = new TunnelConnectSessionEventArgs(endPoint);
connectArgs.WebSession.Request = connectRequest;
connectArgs.ProxyClient.TcpClient = tcpClient;
connectArgs.ProxyClient.ClientStream = clientStream;
if (TunnelConnectRequest != null)
{
await TunnelConnectRequest.InvokeParallelAsync(this, connectArgs, ExceptionFunc);
}
if (!excluded && await CheckAuthorization(clientStreamWriter, connectArgs) == false)
{
if (TunnelConnectResponse != null)
{
await TunnelConnectResponse.InvokeParallelAsync(this, connectArgs, ExceptionFunc);
}
return;
}
//write back successfull CONNECT response
connectArgs.WebSession.Response = ConnectResponse.CreateSuccessfullConnectResponse(version);
await clientStreamWriter.WriteResponseAsync(connectArgs.WebSession.Response);
var clientHelloInfo = await SslTools.GetClientHelloInfo(clientStream);
bool isClientHello = clientHelloInfo != null;
if (isClientHello)
{
connectRequest.ClientHelloInfo = clientHelloInfo;
}
if (TunnelConnectResponse != null)
{
connectArgs.IsHttpsConnect = isClientHello;
await TunnelConnectResponse.InvokeParallelAsync(this, connectArgs, ExceptionFunc);
}
if (!excluded && isClientHello)
{
httpRemoteUri = new Uri("https://" + httpUrl);
connectRequest.RequestUri = httpRemoteUri;
SslStream sslStream = null;
try
{
var alpnStream = AlpnEnabled ? (Stream) new ServerHelloAlpnAdderStream(clientStream) : clientStream;
sslStream = new SslStream(alpnStream);
string certName = HttpHelper.GetWildCardDomainName(httpRemoteUri.Host);
var certificate = endPoint.GenericCertificate ?? CertificateManager.CreateCertificate(certName, false);
//Successfully managed to authenticate the client using the fake certificate
await sslStream.AuthenticateAsServerAsync(certificate, false, SupportedSslProtocols, false);
//HTTPS server created - we can now decrypt the client's traffic
clientStream = new CustomBufferedStream(sslStream, BufferSize);
clientStreamReader.Dispose();
clientStreamReader = new CustomBinaryReader(clientStream, BufferSize);
clientStreamWriter = new HttpResponseWriter(clientStream);
}
catch
{
sslStream?.Dispose();
return;
}
//Now read the actual HTTPS request line
httpCmd = await clientStreamReader.ReadLineAsync();
}
//Hostname is excluded or it is not an HTTPS connect
else
{
//create new connection
using (var connection = await GetServerConnection(connectArgs, true))
{
if (isClientHello)
{
if (clientStream.Available > 0)
{
//send the buffered data
var data = new byte[clientStream.Available];
await clientStream.ReadAsync(data, 0, data.Length);
await connection.Stream.WriteAsync(data, 0, data.Length);
await connection.Stream.FlushAsync();
}
var serverHelloInfo = await SslTools.GetServerHelloInfo(connection.Stream);
((ConnectResponse)connectArgs.WebSession.Response).ServerHelloInfo = serverHelloInfo;
}
await TcpHelper.SendRaw(clientStream, connection.Stream,
(buffer, offset, count) => { connectArgs.OnDataSent(buffer, offset, count); }, (buffer, offset, count) => { connectArgs.OnDataReceived(buffer, offset, count); });
UpdateServerConnectionCount(false);
}
return;
}
}
//Now create the request
disposed = await HandleHttpSessionRequest(tcpClient, httpCmd, clientStream, clientStreamReader, clientStreamWriter,
httpRemoteUri.Scheme == UriSchemeHttps?httpRemoteUri.Host : null, endPoint, connectRequest);
}
catch (Exception e)
{
ExceptionFunc(new Exception("Error whilst authorizing request", e));
}
finally
{
if (!disposed)
{
Dispose(clientStream, clientStreamReader, clientStreamWriter, null);
}
}
}
public override void Write(byte[] buffer, int offset, int count)
{
if (called)
{
stream.Write(buffer, offset, count);
return;
}
called = true;
var ms = new MemoryStream(buffer, offset, count);
//this can be non async, because reads from a memory stream
var serverHello = SslTools.GetServerHelloInfo(new CustomBufferedStream(ms, (int)ms.Length)).Result;
if (serverHello != null)
{
// 0x00 0x10: ALPN identifier
// 0x00 0x0e: length of ALPN data
// 0x00 0x0c: length of ALPN data again:)
var dataToAdd = new byte[]
{
0x0, 0x10, 0x0, 0x5, 0x0, 0x3,
2, (byte)'h', (byte)'2'
};
int newByteCount = serverHello.Extensions == null ? dataToAdd.Length + 2 : dataToAdd.Length;
var buffer2 = new byte[buffer.Length + newByteCount];
for (int i = 0; i < buffer.Length; i++)
{
buffer2[i] = buffer[i];
}
//this is a hacky solution, but works
int length = (buffer[offset + 3] << 8) + buffer[offset + 4];
length += newByteCount;
buffer2[offset + 3] = (byte)(length >> 8);
buffer2[offset + 4] = (byte)length;
length = (buffer[offset + 6] << 16) + (buffer[offset + 7] << 8) + buffer[offset + 8];
length += newByteCount;
buffer2[offset + 6] = (byte)(length >> 16);
buffer2[offset + 7] = (byte)(length >> 8);
buffer2[offset + 8] = (byte)length;
int pos = offset + serverHello.EntensionsStartPosition;
int endPos = offset + serverHello.ServerHelloLength;
if (serverHello.Extensions != null)
{
// update ALPN length
length = (buffer[pos] << 8) + buffer[pos + 1];
length += newByteCount;
buffer2[pos] = (byte)(length >> 8);
buffer2[pos + 1] = (byte)length;
}
else
{
// add ALPN length
length = dataToAdd.Length;
buffer2[pos] = (byte)(length >> 8);
buffer2[pos + 1] = (byte)length;
endPos += 2;
}
for (int i = 0; i < dataToAdd.Length; i++)
{
buffer2[endPos + i] = dataToAdd[i];
}
// copy the reamining data if any
for (int i = serverHello.ServerHelloLength; i < count; i++)
{
buffer2[offset + newByteCount + i] = buffer[offset + i];
}
buffer = buffer2;
count += newByteCount;
}
stream.Write(buffer, offset, count);
}