smtplib.SMTP should reset internal 'helo' and 'ehlo' state within 'connect()' #85642

Activity

1. Dadeos commented on Aug 4, 2020

   

   Dadeosmannequin

   on Aug 4, 2020

   MannequinAuthor

   More actions

   Attempting to reuse an instance of 'smtplib.SMTP', via invocation of the 'smtplib.SMTP.connect(…)' function, results in an invalid SMTP command sequence being issued to the connected server:

   import smtplib
   
   smtp = smtplib.SMTP()
   smtp.connect('smtp.gmail.com')
   smtp.ehlo_or_helo_if_needed()
   smtp.close()
   try:
       smtp.quit()
   except smtplib.SMTPServerDisconnected:
       pass
   smtp.connect('smtp.gmail.com')
   print(smtp.mail('user@example.com'))
   

   results in "(503, b'5.5.1 EHLO/HELO first. … - gsmtp')"

   The values stored in 'self.helo_resp' and 'self.ehlo_resp', as considered within 'smtplib.SMTP.ehlo_or_helo_if_needed()' [1], should be reset to a value of 'None' upon successfully establishing a new connection to a server. The correct sentiment is expressed within 'smtplib.SMTP.quit()' [2] but this resetting of state should be performed upon establishing a new connection rather than termination of an old connection. Whilst the simplified example provided is arguably an invalid use of the 'smtplib.SMTP' library the scenario can occur, specifically when the initial connection is unilaterally terminated by the server, which makes the reset logic provided in 'smtplib.SMTP.quit()' inaccessible due to the 'smtplib.SMTPServerDisconnected' exception raised as a consequence of attempting to execute an SMTP 'QUIT' command over a disconnected socket.

   [1]

   cpython/Lib/smtplib.py

   Line 603 in da51ba4

   if self.helo_resp is None and self.ehlo_resp is None:

   
   [2] https://github.com/python/cpython/blob/da51ba442c7bf717872633676207c1ae10e99c99/Lib/smtplib.py#L989L990
2. Dadeos

   added

   3.8 (EOL)end of lifeend of life

   topic-email

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Aug 4, 2020
3. ezio-melotti

   transferred this issue fromon Apr 10, 2022
4. iritkatriel

   added

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   on Nov 23, 2023