mstack-cpp 🧐

mstack-cpp is a Linux user-space TCP / IP stack based on TUN / TAP devices implemented in C++20.

This project aims to implement a SIMPLE and READABLE TCP / IP user-space protocol stack. Although it is not sound and cannot be used on a large scale, it is an excellent opportunity to explore the composition of the TCP / IP protocol stack. At the same time, it can help us to understand the various trade-offs on the architecture of the protocol stack.

Unlike C-style procedural programming, C++ has features such as object-oriented programming and meta-programming. This project uses c++ skills as much as possible to show a more explicit and more modern protocol stack.

Prerequisites

• You MUST have /dev/net/tun device based on linux
• CMake
• fmt
• glog

Running

mkdir build && cd build && cmake .. && make && sudo ./mstack

Current Feature

• Ethernet II frame
• ARP reply, simple caching
• ICMP reply
• IPv4 packet handling, checksum
• TCPv4 Handshake
• TCP RFC793 "Segment Arrives"

Doing Feature

• ARP request
• TCP RFC6298 Retransmission calculation
• TCP RFC793 User Timeout
• TCP data transmission
• TCP Window Management
• TCP Congestion Control
• Server socket API calls (bind, accept...)

Upcoming Feature

• IP Fragmentation
• IP/ICMP Diagnostics
• TCP Selective Acknowledgments (SACK)
• TCP Silly Window Syndrome Avoidance
• TCP Zero-Window Probes
• ...

References

• level-ip
• seastar