Re: [9fans] telnet vs. godaddy whois

[erik quanstrom <quanstro@quanstro.net>]

On Thu Apr 17 19:07:09 EDT 2008, forsyth@terzarima.net wrote:
> anyway, perhaps the more important question, at least for erik, is: will
> his change cause trouble elsewhere?  unfortunately, we don't know, but we'll
> see how he gets along!
>

not setting the PSH bit when there's no data does fix the problem and
has run for several days on some well-used machines without causing
any issues with telnet, http, smtp, srv, cpu, import -E ssl &c.  i would be surprised
if the change caused any problem between plan 9 machines as the PSH bit
may be set but is never tested.

bwc points out that godaddy's behavior is very likely a violation of the rfc.
while the PSH bit may be mistaken, compliant implementations are supposed
to be liberal with what they accept.  i can only assume that they are trying to
defend against some sort of dos attack.  perhaps someone has a better suggestion?

it was suggested that the } was prehaps misplaced.  i think this is not correct
as the preceeding if modifieds dsize so i believe the ifs need to be seperate.

/n/sources/plan9//sys/src/9/ip/tcp.c:2529,2535 - tcp.c:2529,2535
  			}
  		}

- 		if(sent+dsize == sndcnt)
+ 		if(sent+dsize == sndcnt && dsize)
  			seg.flags |= PSH;

  		/* keep track of balance of resent data */

- erik