bpo-36094: Fix a bug in smtplib module

[Tyrone-Zhao]

The following bug occurs when you connect after creating an instance of SMTP_SSL:

import smtplib


smtp_server = "smtp.163.com"
con2 = smtplib.SMTP_SSL()
con2.connect(smtp_server, 465)

ValueError:
server_hostname cannot be an empty string or start with a leading dot.
File "E:\code\noUse.py", line 8, in
con2.connect(smtp_server, 465)

https://bugs.python.org/issue36094

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[eamanu]

Good PR, please consider my comment.

Please sign CLA

[eamanu]

I think that the correct way is adding on __init__() the self._host = host

[Tyrone-Zhao]

I don't think so. Cause you make a instance first, the host get "" all the time. I think the best way it's put the "self._host = host" in the connect() function. I'll try for it.

[maxking]

I feel like this is probably a better solution than setting _host for the instance. Most of the connect and _get_socket methods take the host and port as input and use that instead of the one defined in the class and from that point-of-view, the use of self._host seems like a bug here.

[maxking]

I think it would be better to change the use of self._host to host, like the first commit to this PR.

Please also add a NEWS file.

[bedevere-bot]

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[csabella]

@Tyrone-Zhao please address the code review from @maxking. Thank you!

[amcgregor]

It's October. Is this going to be corrected? Passing host/port at initialization time is unacceptable and unworkable, as the time of configuration is widely divorced from the time of connection, lazily on the first delivery attempt. And repeatedly, as the pool churns through workers and needs to re-connect when reaching pipelining limits. The next major will issue a warning on any SMTP use, as a deprecated interface, but that's ancillary.