# ZeusTP

## Intro

First a short introduction of what networks layers are and where we will build our protocol on.


Above you see the [7 layer OSI model](https://en.wikipedia.org/wiki/OSI_model). We will utilize the data link layer to build. This means that all layers above it will be out of scope.

## General

This image represents the structure of and Ethernet Frame.


We will follow this structure and we add some extra structure in the Data block.

**Header is 14 bytes**
- Destination MAC: `<6 bytes>`
- Source MAC: `<6 bytes>`
- Protocol: `<2 bytes>`

**After that we add our custom data**
- Padding: `<2 bytes>`
- Sup-protocol: `<2 bytes>`
- Message: `<42-1496 bytes>`

A list of already existing ethernet protocol types: [list of used protocol types](https://www.cavebear.com/archive/cavebear/Ethernet/type.html)

# Protocollen
## Registratie
- Protocol: `0x5001`

1. Client: Ik heb deze naam(broadcast)
2. Server: Oke je krijgt deze callsign | Error: Die naam heeft al callsign XXY

### Detail
Client kiest een naam -> X

- Dest: Broadcast
- Src: Client MAC
- Message: `[Registratie_type: 0x00][Ik wil X zijn]`

Server antwoord callsign -> Y `[A-Z]{2}[0-9]`

- Dest: Client MAC
- Src: Server MAC
- Message: `[Registratie_type: 0x01][Je callsign is Y]`

Error

- Dest: Client MAC
- Src: Server MAC
- Message: `[Registratie_type: 0x99][Hopefully some useful info]`

### Types
- 0x00: Aanvraag voor callsign van naam
- 0x01: Antwoord met callsign
- 0x99: Er is iets fout gegaan

## ARP
- Protocol: `0x5002`

### Detail

1. Client1 zoekt een id -> X
- Dest: Broadcast
- Src: Client1 MAC
- Message: `[ARP_type: 0x00][Wie is X]`

2. Client2 met id X antwoord
- Dest: Client1 MAC
- Src: Client2 MAC
- Message: `[ARP_type: 0x01][Ik ben X]`

### Types
- 0x00: Wie is _id_
- 0x01: Ik ben X

## Data connectie
- Protocol: `0x5003`

1. Client stuurt bericht
- Dest: Server mac
- Src: Client mac
- Message: `[Data_type: 0x00][Src_id <4 bytes>: client callsign][Ping]`
2. Server antwoord
- Dest: Client mac (gevonden via arp)
- Src: Server mac
- Message: `[Data_type: 0x01][Src_id <4 bytes: server callsign>][Pong <some hash>]`