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Re: odd behavior in enforcing of message size limits
John G Myers writes:
> Matti Aarnio <mea@nic.funet.fi> writes:
> > Pardon me, but how does the PIPELINING step in with CHUNKING ?
>
> Unlike DATA, BDAT is designed so that you can pipeline the contents of
> the message when PIPELINING is also supported. You save a round trip.
Hmm.. The specs is still ambiguous at how the PIPELINING relates
to CHUNKING -- I must talk with Greg Vaudreuil about it, I guess.
> > Now instead of waiting the half-duplex handshake at each line,
> > the SMTP-client waits for all of the reports after it has sent
> > the "DATA" command, and has flushed possible stdio buffers to
> > the connection (thats how I do it at ZMailer SMTP-client).
>
> To use PIPELINING on the client, you have to make sure you don't
> deadlock--see paragraph 6 of section 2.1 of RFC 1854. Generally, I
> think it's easier to use select() and nonblocking mode.
Yes, but WHEN to drain the round-trip of inputs, and replies ?
The basic PIPELINING says it happens with DATA command,
but how to do it with BDAT ? It would not make sense to feed
100 kB to the recipient just to sync the status reports of the
envelope...
> > Now if we add this BDAT mode ( = chunking ? )
> > .... mumble mumble (reading the RFC) ... Oh, I see:
> > "When streaming, the receiver SMTP must accept, and discard
> > additional BDAT chunks after the failed BDAT".. (until the
> > "BDAT nn LAST", I suppose..)
>
> It's probably easiest to always parse the nn and discard the data
> whenever you're not in a state where you can actually process the
> data, as opposed to only doing this until you get a BDAT nn LAST.
Juggling the code... yes, rather simple to do it that way.
...
> > Will you test it, John ?
>
> I'm not doing much SMTP development myself; I concentrate on IMAP
> (which does have similar issues). If you contact Ned Freed,
> ned@innosoft.com, he should be able to point you at an implementation
> of CHUNKING that you can test against.
Nope, Mr. Vaudreuil is the author.
> > And by the way: utu.fi mailhost has not talked with any
> > system implementing CHUNKING keyword at EHLO responce during
> > the last 10 (or so) days.
>
> CHUNKING is rather new.
Yeah, August 1995 :-)
> --
> _.John G. Myers Internet: jgm+@CMU.EDU
/Matti Aarnio <mea@nic.funet.fi>
- Follow-Ups:
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- From: John Gardiner Myers <jgm+@CMU.EDU> (Mon, 8 Jul 1996 22:27:36 +0300)