simpleserver.py

#!/usr/bin/env python3

"""Server

Creates a TCP server on a given port

Usage: $ python3 simpleserver.py <port>
"""

import signal
import socket
import sys
from types import FrameType
from typing import Optional

sock = None


def handler(signum: int, frame: Optional[FrameType]) -> None:
    """Handles interrupt and prompts if program should be ended

    Args:
        signmum (int): Type of interrupt
        frame (FrameType): Source of interrupt
    """
    reply = input("trl-c was pressed. Exit? y/n ")
    if reply == "y":
        sock.close()
        sys.exit(1)


def server(port: str) -> None:
    """Starts a simple server on given port

    Args:
        port (str): The port of the server
    """
    try:
        global sock
        port = int(port)
        host = socket.gethostname()
        # Socket that is IPv4 and TCP
        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        sock.bind((host, port))
        sock.listen(1)
        print("[+] Server started")
        while 1:
            conn, addr = sock.accept()
            print(f"[+] Connected to {addr}")
            msg = f"Received connection from {addr}"
            conn.send(msg.encode("ascii"))
    except Exception as e:
        print(f"[-] Server failed: {e}")
        sys.exit(1)


if __name__ == "__main__":
    if len(sys.argv) < 2:
        print(f"[!] Usage: python3 {sys.argv[0]} <port>")
        sys.exit(1)
    signal.signal(signal.SIGINT, handler)
    server(sys.argv[1])