# -*- coding: utf-8 -*-
# Trap 22 / N-6 trustworthy reproduction probe: rapid reconnect to a device listener.
#
# Failure under test (original report): after a rapid reconnect (<~1s) on a
# relistened socket, the chip completes the handshake but the MCU never gets
# standalone accept -> the socket stays LISTENING -> later the chip auto-closes it
# -> THE LISTENER DIES PERMANENTLY (all later SYNs refused, no self-recovery).
#
# Judgement is purely client-side (no firmware probes):
#   * every round must (re)connect successfully within --timeout
#   * on failure the probe keeps retrying for --recover-s to distinguish
#     "transient" from "permanently dead listener"
#
# Usage: tcp_reconnect_probe.py [--host 192.168.1.100] [--port 21] [--rounds 50]
#                               [--gap-ms 600] [--timeout 3] [--recover-s 10]
#                               [--banner]   (read one line after connect, e.g. FTP 220)
# Output:
#   TS <epoch>
#   ROUND <n> gap=<ms> connect=<OK|FAIL:reason> recovered=<na|yes|no>
#   SUMMARY rounds=<n> ok=<n> fail=<n> unrecovered=<n>
# Exit: 0 all rounds connected / 1 any failure / 2 usage
import argparse, socket, sys, time

def log(m):
    sys.stdout.write(m + "\n"); sys.stdout.flush()

def try_connect(host, port, timeout, banner):
    s = socket.create_connection((host, port), timeout=timeout)
    if banner:
        s.settimeout(timeout)
        try:
            s.recv(256)            # e.g. FTP "220 ..." greeting
        except socket.timeout:
            pass
    return s

def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--host", default="192.168.1.100")
    ap.add_argument("--port", type=int, default=21)
    ap.add_argument("--rounds", type=int, default=50)
    ap.add_argument("--gap-ms", type=int, default=600)
    ap.add_argument("--timeout", type=float, default=3.0)
    ap.add_argument("--recover-s", type=float, default=10.0)
    ap.add_argument("--banner", action="store_true")
    a = ap.parse_args()

    nok = nfail = nunrec = 0
    for n in range(1, a.rounds + 1):
        log("TS %d" % int(time.time()))
        res = "OK"
        recovered = "na"
        try:
            s = try_connect(a.host, a.port, a.timeout, a.banner)
            s.close()
        except Exception as e:
            res = "FAIL:%s" % type(e).__name__
            # keep probing: transient (relisten window) or permanently dead?
            t0 = time.time()
            recovered = "no"
            while time.time() - t0 < a.recover_s:
                time.sleep(0.5)
                try:
                    s = try_connect(a.host, a.port, a.timeout, a.banner)
                    s.close()
                    recovered = "yes"
                    break
                except Exception:
                    pass
        ok = (res == "OK")
        nok += 1 if ok else 0
        nfail += 0 if ok else 1
        if not ok and recovered != "yes":
            nunrec += 1
        log("ROUND %d gap=%d connect=%s recovered=%s" % (n, a.gap_ms, res, recovered))
        if a.gap_ms > 0 and n < a.rounds:
            time.sleep(a.gap_ms / 1000.0)
    log("SUMMARY rounds=%d ok=%d fail=%d unrecovered=%d" % (a.rounds, nok, nfail, nunrec))
    return 0 if nfail == 0 else 1

sys.exit(main())