https://github.com/shresth72/tcp_rust

Tcp Implementation in rust | RFC 793 | IPv4 | "a lot of TODOs left"
https://github.com/shresth72/tcp_rust

bash ipv4 rust tcp tun-tap

Last synced: 19 days ago
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Tcp Implementation in rust | RFC 793 | IPv4 | "a lot of TODOs left"

• Host: GitHub
• URL: https://github.com/shresth72/tcp_rust
• Owner: Shresth72
• Created: 2024-04-29T12:34:27.000Z (9 months ago)
• Default Branch: main
• Last Pushed: 2024-05-17T12:12:25.000Z (9 months ago)
• Last Synced: 2024-11-14T05:28:08.630Z (3 months ago)
• Topics: bash, ipv4, rust, tcp, tun-tap
• Language: Rust
• Homepage:
• Size: 83 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# TCP Implementation in Rust

## 1. Core Functionality

### RFC 793: "Transmission Control Protocol"

> Usually, the user space sends network requests to the Kernel using sockets and has a pointer to the kernel memory (that represents the TCP connection) inside the Kernel. Then, the Kernel already knows how to deliver packets to the internet.

> However, using Sockets for implementing our own TCP might cause conflicts as Kernel already implements it's own TCP to talk to the internet.

#### 1. Emulate network inside the user's space using a TUN device

- Hence, using a Linux feature called TUN/TAP provides packet reception and transmission for user space program. Instead of receiving and writing packets from a physical media, it receives them from user space program and writes them to the user program respectively.

- In this, Kernel creates a virtual space for us. So, Kernel treats the TUN interface as it's own network interface. So, any send the Kernel does turns into a receive for the user program and any write by the user program goes through the TUN, and appear to the kernel as a network IP packet.

- TUN has it's own IP Protocol and network metadata.

#### 2. Receiving and Parsing TCP Packet Header (SYN)

TCP Packet Frame Format :

- **Flags [2 bytes]**

- **Proto [2 bytes]**

  - 0x086dd Ethernet Type for IPv6 


  - 0x0800 ICMP - Protocol 1 (Ping) 


  - TCP - Protocol 6 


- **Raw Protocol(IP, IPv6, etc) frame**

Receiving these packets with their headers parsed performs the `SYN` action of the TCP Protocol

#### n. Three Way Handshake for Connection Synchronization

### RFC 1122: "Requirements for Hosts - Communication Layers"

-

### RFC 2873: "TCP Processing of the IPv4 Precedence Field"

-

### RFC 5681: "TCP Congestion Control"

-