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Issue with ftplib.FTP_TLS and server forcing SSL connection reuse #69623
Description
| BPO | 25437 |
|---|---|
| Nosy | @tiran |
| Superseder |
Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.
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GitHub fields:
assignee = None
closed_at = <Date 2016-09-08.23:09:48.027>
created_at = <Date 2015-10-18.19:44:18.180>
labels = ['type-bug', 'library']
title = 'Issue with ftplib.FTP_TLS and server forcing SSL connection reuse'
updated_at = <Date 2016-09-08.23:09:48.025>
user = 'https://bugs.python.org/dwaites'bugs.python.org fields:
activity = <Date 2016-09-08.23:09:48.025>
actor = 'christian.heimes'
assignee = 'none'
closed = True
closed_date = <Date 2016-09-08.23:09:48.027>
closer = 'christian.heimes'
components = ['Library (Lib)']
creation = <Date 2015-10-18.19:44:18.180>
creator = 'dwaites'
dependencies = []
files = []
hgrepos = []
issue_num = 25437
keywords = []
message_count = 3.0
messages = ['253161', '253162', '275208']
nosy_count = 3.0
nosy_names = ['christian.heimes', 'dwaites', 'Stephen Ash']
pr_nums = []
priority = 'normal'
resolution = 'duplicate'
stage = None
status = 'closed'
superseder = '19500'
type = 'behavior'
url = 'https://bugs.python.org/issue25437'
versions = ['Python 2.7', 'Python 3.4']
Activity
dwaites commentedon Oct 18, 2015
There is an issue with the python FTPS module in the standard library which appears to be related to SSL session reuse. I noticed when I updated to a recent version of Pure-FTPd (1.0.42), python's FTPS library client stopped working and generated an error in the ssl unwrap call when a data connection is opened after prot_p() is used. Checking the change log on that version of Pure-FTPd, there is this note:
1.0.22 circa 2009, but disabled back then due to client compatibility
concerns) is now on by default, except in broken clients compatibility mode.
Turning on the broken clients compatibility mode in pure-ftpd makes the Python client work again, so I'm surmising this is related to pure-ftpd forcing SSL session reuse. My question is, is this something the Python standard library should detect, or is it a problem lower in the stack (i.e., libssl?) Incidentally, I can reproduce this behavior on Python 2.7 as well.
Steps to reproduce:
Traceback (most recent call last): File "/home/dwaites/bin/mysqlload.py", line 212, in main() File "/home/dwaites/bin/mysqlload.py", line 155, in main site.retrbinary('RETR ' + cmofile, infile.write) File "/usr/lib/python3.4/ftplib.py", line 449, in retrbinary conn.unwrap() File "/usr/lib/python3.4/ssl.py", line 788, in unwrap s = self._sslobj.shutdown() OSError: [Errno 0] Errordwaites commentedon Oct 18, 2015
Incidentally, there appears to be an old bug report with a similar error message, although the error is encountered in a different context. http://bugs.python.org/issue10808 . Evidently, errors encountered in libssl aren't necessarily being propagated up to python.
tiran commentedon Sep 8, 2016
I'm going to add session support in bpo-19500 (3.6).