Messages in this thread | | | Date | Tue, 12 Jan 2021 16:42:49 -0800 | From | Enke Chen <> | Subject | Re: [PATCH] tcp: keepalive fixes |
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Hi, Yuchung:
I have attached the python script that reproduces the keepalive issues. The script is a slight modification of the one written by Marek Majkowski:
https://github.com/cloudflare/cloudflare-blog/blob/master/2019-09-tcp-keepalives/test-zero.py
Please note that only the TCP keepalive is configured, and not the user timeout.
Thanks. -- Enke
On Tue, Jan 12, 2021 at 02:48:01PM -0800, Yuchung Cheng wrote: > On Tue, Jan 12, 2021 at 2:31 PM Enke Chen <enkechen2020@gmail.com> wrote: > > > > From: Enke Chen <enchen@paloaltonetworks.com> > > > > In this patch two issues with TCP keepalives are fixed: > > > > 1) TCP keepalive does not timeout when there are data waiting to be > > delivered and then the connection got broken. The TCP keepalive > > timeout is not evaluated in that condition. > hi enke > Do you have an example to demonstrate this issue -- in theory when > there is data inflight, an RTO timer should be pending (which > considers user-timeout setting). based on the user-timeout description > (man tcp), the user timeout should abort the socket per the specified > time after data commences. some data would help to understand the > issue. >
------ #! /usr/bin/python
import io import os import select import socket import time import utils import ctypes
utils.new_ns()
port = 1
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) s.bind(('127.0.0.1', port)) s.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, 1024)
s.listen(16)
tcpdump = utils.tcpdump_start(port) c = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) c.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, 1024) c.connect(('127.0.0.1', port))
x, _ = s.accept()
if False: c.setsockopt(socket.IPPROTO_TCP, socket.TCP_USER_TIMEOUT, 90*1000)
if True: c.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1) c.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPCNT, 5) c.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 10) c.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPINTVL, 10)
time.sleep(0.2) print("[ ] c.send()") import fcntl TIOCOUTQ=0x5411 c.setblocking(False) while True: bytes_avail = ctypes.c_int() fcntl.ioctl(c.fileno(), TIOCOUTQ, bytes_avail) if bytes_avail.value > 64*1024: break try: c.send(b"A" * 16384 * 4) except io.BlockingIOError: break c.setblocking(True) time.sleep(0.2) utils.ss(port) utils.check_buffer(c)
t0 = time.time()
if True: utils.drop_start(dport=port) utils.drop_start(sport=port)
poll = select.poll() poll.register(c, select.POLLIN) poll.poll()
utils.ss(port)
e = c.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR) print("[ ] SO_ERROR = %s" % (e,))
t1 = time.time() print("[ ] took: %f seconds" % (t1-t0,))
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