#!/usr/bin/env python3
"""Minimal NFQUEUE example: accept every packet from a queue."""

import signal
import sys

try:
    from netfilterqueue import NetfilterQueue
except Exception as exc:
    print(f"Failed to import netfilterqueue: {exc}", file=sys.stderr)
    sys.exit(2)

nfq = NetfilterQueue()


def _handle_packet(packet) -> None:
    packet.accept()


def _stop(_sig, _frame) -> None:
    raise SystemExit(0)


def main() -> int:
    if len(sys.argv) != 2:
        print("Usage: hello_nfqueue.py <qnum>", file=sys.stderr)
        return 1

    try:
        qnum = int(sys.argv[1])
    except ValueError:
        print("qnum must be an integer", file=sys.stderr)
        return 1

    signal.signal(signal.SIGINT, _stop)
    signal.signal(signal.SIGTERM, _stop)

    nfq.bind(qnum, _handle_packet)
    try:
        nfq.run()
    except KeyboardInterrupt:
        pass
    finally:
        nfq.unbind()
    return 0


if __name__ == "__main__":
    raise SystemExit(main())