TCP Help

[twitchyliquid64]

Hi all.

I am Currently Building a HTTP Proxy/VPN Hybrid system and am having trouble with TCP Framing. There are 2 components to my program.

1. Client – A program locally runs on the users computer, hosting a HTTP Proxy server. It connects to the VPN server, and routes the HTTP proxy requests through that.

2. Server – This runs on a separate machine and is responsible for getting the HTTP Data sent down from the client, and connecting to the various hosts and making it happen.

So it goes like this: Browser -> Local (127.0.0.1) HTTP Proxy -> VPN Server -> Host, and back again.

Parts of the VPN Link are encrypted.

The issue Im having is that everything that’s not a html or css document, or overhead, isn’t getting sent correctly.

The Structure for a section of the HTTP Data is as follows:

SEND:(SOCKET ON VPN):(CONTENT LEN):(CONTENT)

This should allow multiple packets to be ‘stacked up’ without it failing.

But somewhere, some how, something its working as intended. I have spent hours debugging and have no idea. Here is my code:

Receiving HTTP Data from VPN Server:

$conrecv = TCPRecv( $conn_sock, 9999)
        $Portal_BUFFER &= $conrecv
        ;Some irrelevant bits in the middle
        if StringLeft( $Portal_BUFFER, 4) = "SEND" Then
            $split = StringSplit( $Portal_BUFFER, ":")
            $pos = Locate_portal( $split[2])
            if $split[1] = "SEND" Then
                $startcutlen = StringLen("SEND:::"&$split[2]&$split[3])
                ConsoleWrite("INCOMING DATA:" & @CRLF & BinaryToString(_Crypt_DecryptData(StringMid($Portal_BUFFER, $startcutlen+1, $split[3]),$hKey,$CALG_USERKEY)) & @CRLF)
                TCPSend( $DEVICE_SOCKET[$Portal_USERID[$pos]], _Crypt_DecryptData(StringMid($Portal_BUFFER, $startcutlen+1, $split[3]),$hKey,$CALG_USERKEY))
            EndIf
            $Portal_BUFFER = StringTrimLeft($Portal_BUFFER, $startcutlen+StringLen( StringMid($Portal_BUFFER, $startcutlen+1, $split[3])))
            ConsoleWrite(@CRLF &@CRLF & "SEND FIN, BUFFER: " & $Portal_BUFFER)
        EndIf

Sending HTTP Data from VPN Server:

$server_data = TCPRecv( $SERVER_Socket[$x], 9999)
            if @error then
                Close_Server_Socket( $x)
                ContinueLoop
            EndIf
            $count = StringLen( $server_data)
            if $server_data <> "" then ;LOOpY DOOPY Round to send all data.
                $snd = $server_data
                Do
                    $senddata = _Crypt_EncryptData(StringLeft( $snd, 4558),$hKey,$CALG_USERKEY)
                    $snd = StringTrimLeft( $snd, StringLen($senddata))
                    TCPSend( $User_Socket_array[$SERVER_User[$x]], "SEND:"&$SERVER_Socket[$x]&":"&StringLen($senddata)&":"&String($senddata))
                    ConsoleWrite("Sending: " & "SEND:"&$SERVER_Socket[$x]&":"&StringLen($senddata)&":"&$senddata & @CRLF)
                    Sleep(150)
                Until StringLen($snd)<=0
            EndIf

Thanks in advance.

[twitchyliquid64]

BUMP come on guys I really need some help.

Thanks in advance.