Assembling Bytes into packets.

[twitchyliquid64]

Hi all,

This is a simple question - I want to assemble a message to send in a TCP connection (specifically, guntella)

This is what the packet will contain.

GUNTELLA HEADER STRUCTURE:

Byte Pos Name

0 - 15 Message ID

16 Function ID

17 TTL Remaining

18 Hops taken

19 - 22 Data Length

Firstly, how do I individually 'make' data in this fashion? Secondly, how do I 'string' them together?

if your wondering? Ill use the guntella network as a backup to find peers for my p2p network.

Thx in advance,

-Twitchy.

Edited April 13, 2013 by twitchyliquid64

[trancexx]

That's fairly simple task using dllstruct:

$GUNTELLA_HEADER = DllStructCreate("byte MessageID[16];" & _
        "byte FunctionID;" & _
        "byte TTLRemaining;" & _
        "byte Hopstaken;" & _
        "dword DataLength;")
;... set fields here ...

; Binary:
$bBinary = DllStructGetData(DllStructCreate("byte[" & DllStructGetSize($GUNTELLA_HEADER) & "]", DllStructGetPtr($GUNTELLA_HEADER)), 1)

[twitchyliquid64]

That's fairly simple task using dllstruct:

$GUNTELLA_HEADER = DllStructCreate("byte MessageID[16];" & _
        "byte FunctionID;" & _
        "byte TTLRemaining;" & _
        "byte Hopstaken;" & _
        "dword DataLength;")
;... set fields here ...

; Binary:
$bBinary = DllStructGetData(DllStructCreate("byte[" & DllStructGetSize($GUNTELLA_HEADER) & "]", DllStructGetPtr($GUNTELLA_HEADER)), 1)

So then would I just do...

$GUNTELLA_HEADER = DllStructCreate("byte MessageID[16];" & _
        "byte FunctionID;" & _
        "byte TTLRemaining;" & _
        "byte Hopstaken;" & _
        "dword DataLength;")
$FunctionID = ;Um, however you make 16 bytes of randomness
$TTLRemaining = 8
$Hopstaken = 0
$DataLength = 0
; Binary:
$bBinary = DllStructGetData(DllStructCreate("byte[" & DllStructGetSize($GUNTELLA_HEADER) & "]", DllStructGetPtr($GUNTELLA_HEADER)), 1)

??? How do you 'set' in Dllstruct???

[trancexx]

Usually by using DllStructSetData function.

[twitchyliquid64]

Im still confused: how would I make say 0x50 in the data on the first place? is there any way i can do this without any complex dll structs??? (thx by the way, you walk on golden sand )

?????

$GUNTELLA_HEADER = DllStructCreate("byte MessageID[16];" & _
         "byte FunctionID;" & _
         "byte TTLRemaining;" & _
         "byte Hopstaken;" & _
         "dword DataLength;") 

DllStructSetData ( $GUNTELLA_HEADER, "FunctionID", 0x50)

$bBinary = DllStructGetData(DllStructCreate("byte[" & DllStructGetSize($GUNTELLA_HEADER) & "]", DllStructGetPtr($GUNTELLA_HEADER)), 1)

????

Edited December 18, 2010 by hyperzap

[twitchyliquid64]

This will help you understand what I plan to do and how the messages must be structured; im not very good at explaining.

http://capnbry.net/gnutella/protocol.php

The end result (once Ive figured out how to generate the packets) will hopefully be a UDF to fully interact with the Guntella network.