9fans archive / 2008 / 04 / 274 /    prev next

From: Bakul Shah <bakul+plan9@bit...>
Subject: Re: [9fans] telnet vs. godaddy whois
Date: Mon, 21 Apr 2008 15:07:30 -0700

On Mon, 21 Apr 2008 22:24:35 BST Charles Forsyth <forsyth@ter...>  wrote:
> >      must not buffer data indefinitely, and (2) MUST set the
> >      PSH bit in the last buffered segment (i.e., when there
> >      is no more queued data to be sent).
> > 
> > The implication is that the "preceding segment" to a pkt with
> > no data *will have* PSH set.
> 
> so does the implementation do that?

Do you mean plan9 after the change?  The traces I looked at
seem to do that. Others certainly seem to do that.

> can you prove it in all cases?

Not in the formal sense. Not enough free time or incentive.

> what will break if we just change it without knowing?
> after all, it has been 15 years to come across a botched receiver's implement
> ation
> of PSH (ie, godaddy's) which is the only reason to change it.
> that's what i was pointing out. i could do the work myself, i suppose, but i 
> haven't got the incentive.

I understand your concern about possibly breaking things with
this change. It should certainly be tested more thoroughly
but since the change brings Plan9 behavior more in line with
what *BSD/Linux/Windows do I am not as apprehensive as you
are.

> >here you have to be compatible with existing
> >implementations as far as possible (in order to maximize
> >interoperability).
> 
> i suspect arguments like that caused the current situation with HTML, CSS and
>  Javascript.
> computing is needlessly regressing.

May be. Somehow this makes me think of E W Dijkstra :-)