python / python/cpython

Unclosed socket in urllib when ftp request times out after connect

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stdlib topic-IO type-bug
Dominant language
Python
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Description

Bug report

Bug description:

Spotted in the log of "Log from "buildbot/ARM64 macOS 3.x"; this doesn't fix the ftp test but when the operation times out in the test CPython should close the socket

This seems to be originating here:
https://github.com/python/cpython/blob/f5394c257ce4118394fe5ff561a2b0ad238a8d65/Lib/urllib/request.py#L1539-L1556

In particular, fw = self.connect_ftp succeeds which means fw contains an open connection but fp, retrlen = fw.retrfile(file, type) fails and the except doesn't result in a fw.close().

Log from "buildbot/ARM64 macOS 3.x" 

Exception ignored while finalizing socket <socket.socket fd=6, family=2, type=1, proto=6, laddr=('192.168.0.101', 57993), raddr=('68.183.26.59', 21)>:
Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 1546, in ftp_open
    fp, retrlen = fw.retrfile(file, type)
                  ~~~~~~~~~~~^^^^^^^^^^^^
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 1826, in retrfile
    conn, retrlen = self.ftp.ntransfercmd(cmd)
                    ~~~~~~~~~~~~~~~~~~~~~^^^^^
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/ftplib.py", line 354, in ntransfercmd
    conn = socket.create_connection((host, port), self.timeout,
                                    source_address=self.source_address)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/socket.py", line 879, in create_connection
    raise exceptions[0]
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/socket.py", line 864, in create_connection
    sock.connect(sa)
    ~~~~~~~~~~~~^^^^
TimeoutError: [Errno 60] Operation timed out

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/test/test_urllib2net.py", line 20, in _retry_thrice
    return func(*args, **kwargs)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 187, in urlopen
    return opener.open(url, data, timeout)
           ~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 487, in open
    response = self._open(req, data)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 504, in _open
    result = self._call_chain(self.handle_open, protocol, protocol +
                              '_open', req)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 464, in _call_chain
    result = func(*args)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 1556, in ftp_open
    raise URLError(f"ftp error: {exp}") from exp
urllib.error.URLError: <urlopen error ftp error: [Errno 60] Operation timed out>

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/test/test_urllib2net.py", line 22, in _retry_thrice
    last_exc = e
    ^^^^^^^^
ResourceWarning: unclosed <socket.socket fd=6, family=2, type=1, proto=6, laddr=('192.168.0.101', 57993), raddr=('68.183.26.59', 21)>
Warning -- Unraisable exception
Exception ignored while finalizing socket <socket.socket fd=8, family=2, type=1, proto=6, laddr=('192.168.0.101', 58055), raddr=('68.183.26.59', 21)>:
Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 1546, in ftp_open
    fp, retrlen = fw.retrfile(file, type)
                  ~~~~~~~~~~~^^^^^^^^^^^^
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 1826, in retrfile
    conn, retrlen = self.ftp.ntransfercmd(cmd)
                    ~~~~~~~~~~~~~~~~~~~~~^^^^^
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/ftplib.py", line 354, in ntransfercmd
    conn = socket.create_connection((host, port), self.timeout,
                                    source_address=self.source_address)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/socket.py", line 879, in create_connection
    raise exceptions[0]
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/socket.py", line 864, in create_connection
    sock.connect(sa)
    ~~~~~~~~~~~~^^^^
TimeoutError: [Errno 60] Operation timed out

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/test/test_urllib2net.py", line 20, in _retry_thrice
    return func(*args, **kwargs)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 187, in urlopen
    return opener.open(url, data, timeout)
           ~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 487, in open
    response = self._open(req, data)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 504, in _open
    result = self._call_chain(self.handle_open, protocol, protocol +
                              '_open', req)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 464, in _call_chain
    result = func(*args)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/urllib/request.py", line 1556, in ftp_open
    raise URLError(f"ftp error: {exp}") from exp
urllib.error.URLError: <urlopen error ftp error: [Errno 60] Operation timed out>

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/test/test_urllib2net.py", line 22, in _retry_thrice
    last_exc = e
    ^^^^^^^^
ResourceWarning: unclosed <socket.socket fd=8, family=2, type=1, proto=6, laddr=('192.168.0.101', 58055), raddr=('68.183.26.59', 21)>

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

Linked PRs
  • gh-140694
  • gh-140835
  • gh-141555
  • gh-141657

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Read ftp_open in Lib/urllib/request.py, especially the connect_ftp and retrfile exception path described in the report. Check test/test_urllib2net.py and verify the timeout case no longer leaves a socket unclosed or emits a ResourceWarning.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
networking
Issue type
Bug
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
25/100

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