#!/usr/bin/env python3
"""
Fake Tor control port for the fd-bug harness.

dragonxd's torcontrol.cpp opens a libevent bufferevent to -torcontrol=<host:port>,
speaks the control protocol (PROTOCOLINFO / AUTHCHALLENGE / AUTHENTICATE / ADD_ONION),
and on EOF/ERROR reconnects with exponential backoff. We give it a server on a
loopback port that behaves badly in several ways so the reconnect/teardown loop
(bufferevent_free with BEV_OPT_CLOSE_ON_FREE, the event_base, the reconnect timer)
runs constantly. Each accepted connection picks a behaviour at random:

  close   : accept, then immediately close (EOF right away)
  rst     : accept, set SO_LINGER 0, close -> sends RST
  stall   : accept, read nothing, hold the socket open then drop it
  garbage : send non-control-protocol bytes then close
  halfok  : answer PROTOCOLINFO plausibly, then drop before AUTHENTICATE completes

Loopback only. Run with --port. Ctrl-C / SIGTERM stops it.
"""
import argparse, random, socket, struct, threading, time, sys, signal

STOP = threading.Event()

def handle(conn, mode):
    try:
        conn.settimeout(5.0)
        if mode == "close":
            conn.close(); return
        if mode == "rst":
            conn.setsockopt(socket.SOL_SOCKET, socket.SO_LINGER,
                            struct.pack("ii", 1, 0))
            conn.close(); return
        if mode == "stall":
            # read whatever the controller sends but never reply; hold 2-4s
            try:
                conn.recv(4096)
            except Exception:
                pass
            time.sleep(random.uniform(2.0, 4.0))
            conn.close(); return
        if mode == "garbage":
            try:
                conn.recv(4096)
            except Exception:
                pass
            conn.sendall(b"\x00\xff\x01garbage not a tor reply\r\n" * 4)
            conn.close(); return
        if mode == "halfok":
            # read the PROTOCOLINFO line, give a plausible 250 reply advertising
            # NULL auth, then drop the connection before AUTHENTICATE finishes.
            try:
                conn.recv(4096)
            except Exception:
                pass
            conn.sendall(b"250-PROTOCOLINFO 1\r\n"
                         b"250-AUTH METHODS=NULL\r\n"
                         b'250-VERSION Tor="0.4.7.13"\r\n'
                         b"250 OK\r\n")
            time.sleep(random.uniform(0.2, 1.0))
            conn.close(); return
    except Exception:
        try: conn.close()
        except Exception: pass

def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--port", type=int, required=True)
    ap.add_argument("--host", default="127.0.0.1")
    args = ap.parse_args()

    modes = ["close", "rst", "stall", "garbage", "halfok"]
    srv = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    srv.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    srv.bind((args.host, args.port))
    srv.listen(16)
    srv.settimeout(1.0)
    print(f"faketor: listening on {args.host}:{args.port}", flush=True)

    def onsig(*_): STOP.set()
    signal.signal(signal.SIGTERM, onsig)
    signal.signal(signal.SIGINT, onsig)

    n = 0
    while not STOP.is_set():
        try:
            conn, _ = srv.accept()
        except socket.timeout:
            continue
        except Exception:
            break
        mode = modes[n % len(modes)]
        n += 1
        threading.Thread(target=handle, args=(conn, mode), daemon=True).start()
    srv.close()
    print(f"faketor: stopped after {n} connections", flush=True)

if __name__ == "__main__":
    main()