Re: SMTP question (not quite Gnus-related)

[Daniel Pittman <daniel@rimspace.net>]

On 07 Feb 2001, Steven E. Harris wrote:
> Daniel Pittman <daniel@rimspace.net> writes:
> 
>> Specifically, the explanation makes it possible to write a
>> stream-oriented SMTP `DATA' reader easily. To be strictly conforming,
>> you read bytes and scan for the sequence described. When you see it
>> and it alone, terminate the reading of the `DATA' command.
> 
> That's exactly what I've written - two of them, in fact. Each is based
> on a different state machine, depending upon differing interpretations
> of RFC821. My question still stands, though:
> 
>   What about an "empty" message?
> 
> Is this supposed to be okay?

It is fine by the fragment you posted. By my reading of it, anyway. 

> ,----
> | DATA<CRLF>
> | .<CRLF>
> `----

That final line is a period on an otherwise empty line, the defined
terminator. Remember that this is legal:

,----
| DATA<crlf>
| text<crlf>
| .<crlf>
`----

So, clearly the initial <crlf> does not need to *exclusively* signal the
end-of-text. As such, making it do double duty for opening and closing
the DATA command seems legal to me.

> If so, then where is the terminator for the "DATA" command string?
> That first <CRLF> either belongs to the "DATA" as a command
> terminator, or to the period as the start of the message
> terminator. It can't be both. 

I don't see any indication in the RFC that the <crlf> sequence at the
end-of-line cannot serve double duty as the start of the indicated octet
sequence for the end-of-data inticatior.

> Most MTAs accept it, though.
> 
> I'm now thinking that a completely empty message like the one above
> isn't a valid RFC822 message anyway, but it still seems like there's a
> hole in RFC821 on this.

*shrug*  I don't think so, you do. That makes it a hole. ;)

        Daniel

-- 
We must put aside the weapons of our minds, 
cross the no man's land come with empty hands. 
Overcome the fear to drop the last defense, 
speak forbidden words reach out beyond ourselves.
        -- Covenant, _Wall Of Sound_