Build a TCP Echo Server from Raw Syscalls - The Networker

                      TASK
                    

Implementation

Build a TCP echo server using raw syscalls. No standard library network abstractions allowed. The server should:

Create a socket using socket(AF_INET, SOCK_STREAM, 0)
Bind to a port using bind()
Listen for connections using listen()
Accept connections using accept()
Read data using read()
Write data back using write()

Implement a Maelstrom node that simulates this:

Request:  {"type": "tcp_echo_start", "msg_id": 1, "port": 8080}
Response: {"type": "tcp_echo_start_ok", "in_reply_to": 1, "status": "listening", "port": 8080}

Request:  {"type": "tcp_echo_send", "msg_id": 2, "data": "hello world"}
Response: {"type": "tcp_echo_send_ok", "in_reply_to": 2, "echoed": "hello world", "bytes": 11}

Request:  {"type": "tcp_echo_stats", "msg_id": 3}
Response: {"type": "tcp_echo_stats_ok", "in_reply_to": 3, "total_connections": 1, "total_bytes": 11}

Sample Test Cases

Start echo serverTimeout: 5000ms

Input

{"src":"c0","dest":"n1","body":{"type":"init","msg_id":1,"node_id":"n1","node_ids":["n1"]}}
{"src":"c1","dest":"n1","body":{"type":"tcp_echo_start","msg_id":2,"port":8080}}

Expected Output

{"src": "n1", "dest": "c0", "body": {"type": "init_ok", "in_reply_to": 1, "msg_id": 0}}
{"src": "n1", "dest": "c1", "body": {"type": "tcp_echo_start_ok", "in_reply_to": 2, "status": "listening", "port": 8080, "msg_id": 1}}

Echo data back correctlyTimeout: 5000ms

Input

{"src":"c0","dest":"n1","body":{"type":"init","msg_id":1,"node_id":"n1","node_ids":["n1"]}}
{"src":"c1","dest":"n1","body":{"type":"tcp_echo_start","msg_id":2,"port":8080}}
{"src":"c1","dest":"n1","body":{"type":"tcp_echo_send","msg_id":3,"data":"hello world"}}

Expected Output

{"src": "n1", "dest": "c0", "body": {"type": "init_ok", "in_reply_to": 1, "msg_id": 0}}
{"src": "n1", "dest": "c1", "body": {"type": "tcp_echo_start_ok", "in_reply_to": 2, "status": "listening", "port": 8080, "msg_id": 1}}
{"src": "n1", "dest": "c1", "body": {"type": "tcp_echo_send_ok", "in_reply_to": 3, "echoed": "hello world", "bytes": 11, "msg_id": 2}}

Hints

Hint 1▾

Use raw socket syscalls: socket(), bind(), listen(), accept(), read(), write()

Hint 2▾

Do not use high-level network abstractions from the standard library

Hint 3▾

The echo server reads data from a client and writes it back unchanged

Hint 4▾

Use SOCK_STREAM for TCP and AF_INET for IPv4

Hint 5▾

Close client connections properly after echoing

Resources

Beej Guide to Network Programming

Classic guide to Unix socket programming from raw syscalls

                      OVERVIEW
                    

Theoretical Hub

Concept overview coming soon

Key Concepts

TCPsocketbindlistenacceptsyscalls

main.py

python