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jazzband / imaplib2

Fork of Piers Lauder's imaplib2 library for Python.
https://imaplib2.readthedocs.io/
MIT License
33 stars 29 forks source link

Not using SNI #5

Closed iliastsi closed 3 years ago

iliastsi commented 6 years ago

Using the latest openssl (version 1.1.1), which supports TLS 1.3, imaplib2 fails to connect to (at least) GMail:

>>> import imaplib2                                                                       
>>> imaplib2.IMAP4_SSL(host="imap.gmail.com", ca_certs="/etc/ssl/certs/ca-certificates.crt")                                                                                         
Traceback (most recent call last):                                                        
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/dist-packages/imaplib2.py", line 2182, in __init__             
    IMAP4.__init__(self, host, port, debug, debug_file, identifier, timeout, debug_buf_lvl)
  File "/usr/lib/python2.7/dist-packages/imaplib2.py", line 360, in __init__
    self.open(host, port)
  File "/usr/lib/python2.7/dist-packages/imaplib2.py", line 2195, in open
    self.ssl_wrap_socket()
  File "/usr/lib/python2.7/dist-packages/imaplib2.py", line 547, in ssl_wrap_socket
    self.sock = ssl.wrap_socket(self.sock, self.keyfile, self.certfile, ca_certs=self.ca_certs, cert_reqs=cert_reqs, ssl_version=ssl_version)
  File "/usr/lib/python2.7/ssl.py", line 949, in wrap_socket                              
    ciphers=ciphers)                                                                      
  File "/usr/lib/python2.7/ssl.py", line 617, in __init__
    self.do_handshake()
  File "/usr/lib/python2.7/ssl.py", line 846, in do_handshake
    self._sslobj.do_handshake()                                                           
ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:726)

This is because imaplib2 does not support SNI, and Google returns an invalid certificate in that case. Copying from here:

Some sites want to encourage the use of SNI and configure a default certificate that fails WebPKI authentication when the client supports TLS 1.3.

Forcing TLS 1.2 works as expected:

>>> import imaplib2
>>> imaplib2.IMAP4_SSL(host="imap.gmail.com", ca_certs="/etc/ssl/certs/ca-certificates.crt", ssl_version="tls1_2")                                                                   
<imaplib2.IMAP4_SSL object at 0x7f1865dec290>
davidben commented 6 years ago

@jcristau, I noticed you wrote a fix in a7ce7da1d573849ac2e1d740d8f3238e0ad8d88c. Were you planning on making a pull request? (I can also put a fix together, but it seemed like you already did it.)

jcristau commented 6 years ago

@davidben I haven't had a chance to test this yet, hence the lack of PR

jcristau commented 6 years ago

Now tested to the extent that i = imaplib2.IMAP4_SSL(host="imap.gmail.com", ca_certs="/etc/ssl/certs/ca-certificates.crt") no longer fails, and i.sock._sslobj.peer_certificate() (py2) or i.sock._sslobj.getpeercert() (py3) looks right.

davidben commented 6 years ago

Ah, okay. :-) I also got confirmation that your patch fixed someone's offlineimap issue.

davidben commented 5 years ago

Any luck?

davidben commented 5 years ago

(Oops, missed that you already opened a PR.)

StoppingBuck commented 5 years ago

Guys, it seems like we've run into a bit of a conundrum: Judging from the commit log, imaplib2 is completely abandoned, with the last commit being a year ago...

edmorley commented 5 years ago

This is starting to become a bigger issue, since OpenSSL 1.1.1 has now been backported to Ubuntu 18.04. Is there anyone who can help us get PR #6 merged and into Python patch releases? :-)

nicolas33 commented 5 years ago

Please, read this comment. The changes are in the 'next' branch so they will likely be included in the next release of offlineimap.