[vworld-tech] Telnet negotiation

Jon Leonard jleonard at slimy.com
Sun Jan 25 18:01:45 PST 2004

On Sun, Jan 25, 2004 at 08:21:48PM -0500, Brian Hook wrote:
> >> - no more local echo, player can't see shit, they need to get a
> >> new client
> >>
> >
> > Right.  Fortunately these clients can just be handled by a server-
> > side hack.
> Which hack specifically?  WILL ECHO and then manually echo back 
> assuming character-mode?

The bit of code I posted in my first reply.  You detect MS-type clients by
the initial one-character packet, and for those clients you echo back all
the bytes they send you.  Well, preferrably with some testing for which
echo state you want them to be in, and with checking that the write() doesn't
fail.  MS telnet reveals that it's not a real telnet long before you'd get to
the echo sequence.

> > *) It may interact oddly with the usual filtering for nul-after
> > carriage-return, and doubling "latin small letter y with diaeresis"
> > (IAC).
> What is CR/NUL?

About 75% of the way through RFC 854 it specifies the handling of various
special characters.  It says to use either "CR LF" or "CR NUL", and that
CR must be avoided in other contexts.  The rationale has to do with making
it reasonable for systems to handle newlines where they do not normally treat
CR and LF independently.


More information about the vworld-tech mailing list