unit ReverseSocks5Server;

interface
uses Socks5Types,ScktComp,Windows, SysUtils,Forms;


type TReverseSocks5Server = class
    function Start(Settings: TReverseSocksSettings; Sockets: TPackedSockets):TPackedSockets;
  private
    procedure OnReceiveFromInternet(Sender: TObject; Socket: TCustomWinSocket);
    procedure OnReceiveFromInterface(Sender: TObject; Socket: TCustomWinSocket);
var
SSettings : TReverseSocksSettings;
SSockets: TPackedSockets;
State: Cardinal;
buf: Array of Char;

destTarget: Array of Byte;
destPort: Word;

tmpBoundAddr: String;
tmpBoundPort: Integer;

AuthFields: TSocksAuth;
Methods: Array [0..255] of Byte;
SelectedMethods: TSocksSelectedMethod;
Request: TSocksRequest;
TargetDataIPv4: TSocksTargetDataIPv4;
TargetDataLengthDomain: TSocksTargetDataDomainLength;
TargetDataDomain: TSocksTargetDataDomain;
TargetPort: TSocksTargetPort;
tmpTargetPort: TSocksTargetPort;
boundtargetport: TSocksTargetPort;
Reply: TSocksReply;

auth: TSocksAuthes;

Username: String;
Password: String;
end;

implementation
uses Unit1;

function TReverseSocks5Server.Start(Settings: TReverseSocksSettings; Sockets: TPackedSockets):TPackedSockets;
begin
  SSettings := Settings; // Set the Settings

  Sockets.InternetSocket.OnRead := Self.OnReceiveFromInternet;
  Sockets.InterfaceSocket.OnRead := Self.OnReceiveFromInterface;

  SSockets := Sockets;
  SSockets.InternetSocket := Form1.ClientSocket2;
end;

procedure TReverseSocks5Server.OnReceiveFromInterface(Sender: TObject; Socket: TCustomWinSocket);
var
I: Integer;
begin
   if State = 0 then begin
      // SUPPORTEDMETHODS.
       Socket.ReceiveBuf(AuthFields, 2); // Receive 2 Bytes
       Socket.ReceiveBuf(Methods,AuthFields.nMethods); // Receive all the Methods

       for i := 0 to AuthFields.nMethods - 1 do begin
         if AuthFields.Methods[i] = Socks_SelectedMethod_AUTH then begin
           if ((config.Username = '') and (config.Password = '')) then begin
             // Ok have no Password but user tries to auth...
             AuthFields.nMethods := 0;
             Socket.SendBuf(AuthFields,2);
           end else begin
             AuthFields.nMethods := 2;
             Socket.SendBuf(AuthFields, 2);
             Socket.ReceiveBuf(auth, SizeOf(auth));

             if auth[0] = 1 then begin
                //get Username
                SetString(username, PChar(@auth[2]),auth[1]);
                //get Password
                SetString(password, PChar(Cardinal(@auth) + 3 + auth[1]), auth[2 + auth[1]]);

                if ((config.Username = username) and (config.password = password)) then begin
                  auth[1] := 0;
                  Socket.SendBuf(auth,2);
                end else begin
                  auth[1] := $FF;
                  Socket.SendBuf(auth,2);
                  exit;
                end;
             end;
           end;
         end else
        if AuthFields.Methods[i] = SOCKS_SelectedMethod_NOAUTH then begin
          if ((config.password = '') and (config.username = '')) then begin
            AuthFields.nMethods := 0;
            Socket.SendBuf(AuthFields, 2);
          end else begin
            AuthFields.nMethods := $FF;
            Socket.SendBuf(AuthFields, 2);
            exit;
          end;
          end else

          if i = AuthFields.nMethods then begin
            AuthFields.nMethods := $FF;
            Socket.SendBuf(AuthFields, 2);
            exit;
          end;

       end;


       // Answering with the Selected Methods
       SelectedMethods.Version := 5; // SOCKS 5!!
       SelectedMethods.Method := SOCKS_SelectedMethod_NOAUTH;

        Socket.SendBuf(SelectedMethods, SizeOf(SelectedMethods));

      State := 2;
    end

    else if State = SOCKS_AUTHSTATE_request then begin
        Socket.ReceiveBuf(Request, 4); // Receive 4 Bytes

        if Request.AddressType = SOCKS_Addresstype_IPv4 then begin
          // IPv4 Adress is requested
          Socket.ReceiveBuf(TargetDataIPv4, 4); // Receive 4 Bytes

          SetLength(desttarget, 4);
          CopyMemory(@desttarget,@TargetDataIPv4.destAddress,Length(destTarget));
        end
        else if Request.AddressType = SOCKS_Addresstype_Domain then begin
          // Domain Name is required
          Socket.ReceiveBuf(TargetDataLengthDomain, 1);
          SetLength(TargetDataDomain.destAddress,TargetDataLengthDomain.destAddressLength);

          Socket.ReceiveBuf(TargetDataDomain.destAddress[0], Length(TargetDataDomain.destAddress));
          SetLength(desttarget, Length(TargetDataDomain.destAddress));
          CopyMemory(@destTarget, @TargetDataDomain.destAddress, Length(destTarget))

        end;

        State := 3;
    end

    else if State = SOCKS_AUTHSTATE_req_allowed then begin
        if not(SizeOf(desttarget) = 0) then begin
            Socket.ReceiveBuf(TargetPort, 2);

            // Invert Port
            tmpTargetPort := TargetPort;

            TargetPort.destPort[1] := tmpTargetPort.destPort[0];
            TargetPort.destPort[0] := tmpTargetPort.destPort[1];

            CopyMemory(@destPort,@TargetPort.destPort,2);

            SSockets.InternetSocket.Host := String(desttarget);
//            SSockets.InternetSocket.Host := 'google.com';
            SSockets.InternetSocket.Port := destPort;
//            SSockets.InternetSocket.Open;
//            SSockets.InternetSocket.Active := true;
{            Form1.ClientSocket2.Host := String(desttarget);
            Form1.ClientSocket2.Port := destPort;}
            Form1.ClientSocket2.Open;

              Request.Command := 0;
              Request.Version := 5;
              Request.AddressType := SOCKS_AddressType_IPv4;
              Request.Reserved := 0;

              Socket.SendBuf(Request, 10);

              Reply.Version := 5;
              Reply.ReplyType := SOCKS_ReplyType_Success;
              Reply.Reserved := 0;
              Reply.AddressType := SOCKS_AddressType_IPv4;

//        Hier verzweifle ich : LocalAddress = "" LocalPort = -1...

              tmpBoundAddr := SSockets.InternetSocket.Socket.LocalAddress;
              CopyMemory(@Reply.sBoundAddr, @tmpBoundAddr, 4);

              tmpBoundPort := SSockets.InternetSocket.Socket.LocalPort;
              CopyMemory(@tmpTargetPort,@tmpBoundPort, 2);

              boundtargetPort.destport[0] := tmpTargetPort.destPort[1];
              boundtargetPort.destport[1] := tmpTargetPort.destPort[0];

              CopyMemory(@Reply.sBoundPort,@BoundTargetPort.DestPort, 2);

          State := SOCKS_AUTHSTATE_Tunneling;
        end; // Error in Connection (perhaps tryed IPv6?)
    end

    else if State = SOCKS_AUTHSTATE_Tunneling then begin
       // Tunneling Work
       if ((SSockets.InternetSocket.Active) and  (SSockets.InterfaceSocket.Active)) then begin
//     Dies tritt fast nie auf da InternetSocket nicht Active ist :[
           i := Socket.ReceiveLength;
           SetLength(buf, i);
           Socket.ReceiveBuf(buf[0], i);

           SSockets.InternetSocket.Socket.SendBuf(buf[0], i);
        end;
     end;
end;

procedure TReverseSocks5Server.OnReceiveFromInternet(Sender: TObject; Socket: TCustomWinSocket);
var
len: Integer;
begin
// Real Socks bekommt nachricht vom InternetZ
  len := Socket.ReceiveLength;
  SetLength(buf, len);
  Socket.ReceiveBuf(buf[0], len);

  SSockets.InterfaceSocket.Socket.SendBuf(buf[0], len);
end;
end.