Duplicated HELO/EHLO

[Varbin]

As already mentioned in source code (

aiosmtpd/aiosmtpd/smtp.py

Line 264 in c25b878

# See issue #21783 for a discussion of this behavior.

, also in original smtpd's code) a second HELO/EHLO is rejected but the standart says it should be handled as a RSET command.

Is there any special reason to not allow duplicated HELO/EHLO? I think the best way is to do the same other SMTP servers do: Allowing a duplicated HELO/EHLO.
Another option is to have a configuration option.

[warsaw]

Do you mean specifically RFC 5321, $4.1.4? I would agree that to be compliant with this section, we should treat a second HELO/EHLO as semantically equivalent to a RSET followed by the HELO/EHLO.

[Varbin]

Yes, I do mean RFC 5321, $4.1.4.

[warsaw]

@Varbin Thanks for the response. I'd like to fix this, but as we're up against the Pycon deadline, I'm going to milestone this to post 1.0.

[Varbin]

I fully understand that. Also the duplicated HELO / EHLO should probably never be a problem - does even one SMTP client send two HELO / EHLO commands in one session?

[warsaw]

@Varbin I wouldn't expect it from a non-buggy client.

[zvyn]

There is a patch for the stdlib implementation at http://bugs.python.org/issue21783, I might find some time to port it over later today.

In terms of relevance: Using HELO or EHLO to reset a session is permitted by the standard so I think we should support it.

I don't know about clients but I did use this when debugging SMTP servers manually before (test something, see what response you get, type EHLO and try something different). In that case it seems better to EHLO instead of RSET to explicitly start a new SMTP session while keeping the TCP connection.

[Varbin]

A patch would be:

....

I just saw you made a pull request...