#!/usr/bin/env python3
# python3 -I winchk.py p1.txt
import asyncio, socket, struct, sys
TIMEOUT, WORKERS = 3.0, 500
OFF = 228  # offset of tcpi_snd_wnd in struct tcp_info (Linux >=5.4)
async def worker(q):
    while True:
        item = await q.get()
        if item is None:
            q.task_done(); return
        ip, port = item
        try:
            r, w = await asyncio.wait_for(asyncio.open_connection(ip, port), TIMEOUT)
            try:
                s = w.get_extra_info("socket")
                buf = s.getsockopt(socket.IPPROTO_TCP, socket.TCP_INFO, 512)
                if len(buf) >= OFF + 4:
                    wnd = struct.unpack_from("<I", buf, OFF)[0]
                    if wnd > 1000:                       # real stack, not win=3
                        print(f"{ip}:{port}\tsnd_wnd={wnd}", flush=True)
            finally:
                w.close()
        except Exception:
            pass
        finally:
            q.task_done()
async def main(path):
    q = asyncio.Queue(maxsize=WORKERS * 4)
    ws = [asyncio.create_task(worker(q)) for _ in range(WORKERS)]
    with open(path) as f:
        for ln in f:
            ln = ln.strip().replace(" ", ":")
            if ln:
                ip, port = ln.rsplit(":", 1)
                await q.put((ip, int(port)))
    await q.join()
    for _ in ws:
        await q.put(None)
    await asyncio.gather(*ws)
asyncio.run(main(sys.argv[1]))