cannot Ctrl-C remote connection when network is flaky

[k4lizen]

Description

My WiFi is flaky. The following just happened to me:
Run script:

p = remote("cs412.epfl.ch", 8004)
p.interactive()
p.close()

WiFi is able to provide DNS resolution, or it might be cached for me, so that passes, but the connection cannot get created, and I see looping message:

[d] Opening connection to cs412.epfl.ch on port 8004:

I want to cancel since I realize what is happening, I press Ctrl-C, but it does not cancel the connection creation / process, it just keeps looping (no matter how many times I press Ctrl-C). So, I have to kill the process.

Request

I want to be able to Ctrl-C during connection creation.

[peace-maker]

Did you see Trying <some IP> in the output too? Otherwise it's still DNS and you could try #2541?

Hard to reproduce :(

[k4lizen]

sorry I don't remember, but I think not

[k4lizen]

i repro'd (i.e. wifi repro'd) it looks like this:

[k4lizen]

if you want you could add some logging to a branch of pwntools, and i will use it and send you a screenshot the next time it happens

[k4lizen]

but also maybe it's not too hard to figure it out even without a repro

[peace-maker]

It's hanging in socket.getaddrinfo while resolving the domain otherwise you'd see an IP.

pwntools/pwnlib/tubes/remote.py

Lines 109 to 116 in fd3cf3d

	with self.waitfor('Opening connection to %s on port %s' % (self.rhost, self.rport)) as h:
	for res in socket.getaddrinfo(self.rhost, self.rport, fam, typ, 0, socket.AI_PASSIVE):
	self.family, self.type, self.proto, _canonname, sockaddr = res
	if self.type not in [socket.SOCK_STREAM, socket.SOCK_DGRAM]:
	continue
	h.status("Trying %s", sockaddr[0])

Can you try #2541 please?

[k4lizen]

oki!

[peace-maker]

@k4lizen got it reproduced with that branch?

[k4lizen]

i am on that branch but didn't use pwntools for connecting to remotes for the past two weeks so no opportunity to repro

[k4lizen]

okay i repro'd. on the branch, it is in fact possible to Ctrl-C out of this, though it is a bit wonky as you need to press Ctrl-C three times.

~❯ ./exploit.py REMOTE
[-] Opening connection to cs412.epfl.ch on port 8000: Failed
Traceback (most recent call last):
  File "/home/user/code/pwntools/build/__editable__.pwntools-5.0.0.dev0-py2.py3-none-any/pwnlib/tubes/remote.py", line 131, in sync_getaddrinfo
    return future.result()
           ~~~~~~~~~~~~~^^
  File "/usr/lib/python3.14/concurrent/futures/_base.py", line 445, in result
    self._condition.wait(timeout)
    ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
  File "/usr/lib/python3.14/threading.py", line 369, in wait
    waiter.acquire()
    ~~~~~~~~~~~~~~^^
KeyboardInterrupt

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/exploit.py", line 36, in <module>
    p = start()
  File "/home/user/exploit.py", line 23, in start
    return remote(os.environ.get("HOST", HOST), int(os.environ.get("PORT", PORT)))
  File "/home/user/code/pwntools/build/__editable__.pwntools-5.0.0.dev0-py2.py3-none-any/pwnlib/tubes/remote.py", line 84, in __init__
    self.sock   = self._connect(fam, typ)
                  ~~~~~~~~~~~~~^^^^^^^^^^
  File "/home/user/code/pwntools/build/__editable__.pwntools-5.0.0.dev0-py2.py3-none-any/pwnlib/tubes/remote.py", line 138, in _connect
    hostnames = sync_getaddrinfo(self.rhost, self.rport, fam, typ, 0, socket.AI_PASSIVE)
  File "/home/user/code/pwntools/build/__editable__.pwntools-5.0.0.dev0-py2.py3-none-any/pwnlib/tubes/remote.py", line 128, in sync_getaddrinfo
    with concurrent.futures.ThreadPoolExecutor() as executor:
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/usr/lib/python3.14/concurrent/futures/_base.py", line 667, in __exit__
    self.shutdown(wait=True)
    ~~~~~~~~~~~~~^^^^^^^^^^^
  File "/usr/lib/python3.14/concurrent/futures/thread.py", line 273, in shutdown
    t.join()
    ~~~~~~^^
  File "/usr/lib/python3.14/threading.py", line 1133, in join
    self._os_thread_handle.join(timeout)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
KeyboardInterrupt

^CException ignored on threading shutdown:
Traceback (most recent call last):
  File "/usr/lib/python3.14/threading.py", line 1577, in _shutdown
    atexit_call()
  File "/usr/lib/python3.14/threading.py", line 1548, in <lambda>
    _threading_atexits.append(lambda: func(*arg, **kwargs))
  File "/usr/lib/python3.14/concurrent/futures/thread.py", line 31, in _python_exit
    t.join()
  File "/usr/lib/python3.14/threading.py", line 1133, in join
    self._os_thread_handle.join(timeout)
KeyboardInterrupt: 

Also the first two KeyboardInterrupt exceptions both appear after the second Ctrl-C.

[k4lizen]

The exception's coloring might be interesting: