Xref: utzoo comp.sources.wanted:5858 comp.protocols.misc:421 comp.protocols.tcp-ip:5808
Path: utzoo!attcan!uunet!auspex!guy
From: guy@auspex.UUCP (Guy Harris)
Newsgroups: comp.sources.wanted,comp.protocols.misc,comp.protocols.tcp-ip
Subject: Re: 'Talk' command and protocol
Keywords: Is this a standard anywhere?
Message-ID: <772@auspex.UUCP>
Date: 21 Dec 88 18:21:41 GMT
References: <1468@cseg.uucp>
Reply-To: guy@auspex.UUCP (Guy Harris)
Organization: Auspex Systems, Santa Clara
Lines: 83

Hoo boy, have *you* opened a can of worms....

>   My main question is:  Is there a standard yet for this 'talk'
> protocol?

Not unless you count the code....

>If so, where could I find it?

In the code.

>If not, then why not,

Beats me.  Probably either

	1) they were too lazy to write it down

	2) they thought it was too err, umm, *specialized* to deserve
	   a protocol spec

	3) they didn't think it was finished yet

or some linear combination of the above.

>and what would it take to produce one?

At minimum, a copy of the 4.3BSD version - which is different from the
4.2BSD version, and even uses a different port number (518 rather than
517), and which makes at least more of an attempt to be
machine-independent.

At most, some more work to fix it up to be machine-independent....

>What is strange is that on each of our different types of computers,
>there was a 'talk   517/udp' entry in the /etc/services file which
>led me to believe that everyone knew about it.  However, I could find NOTHING
>that even referenced it during my search of the RFC's.

"Everybody" who got a BSD source license and ported it, and "everybody"
who got somebody else to do same (compute "transitive closure", if you
will) knows about it.  It's not an official Internet protocol, though,
any more than say "rlogin" is.

CCI got a BSD source license and ported it; that's why Harris has it.

>   My only solution at the moment seems to be to heavily hack the code to work
>for both Harris and Berkeley versions.....

Since you say "talk" and "517", rather than "ntalk" and "518", I assume
the one on the Harris is the 4.2BSD version.  The author of this version
seemed not to be aware, or seemed to have forgotten, that not all
machines have the same byte order as a VAX.  One such machine is the
HCX-7; it has the same byte order as a 68000, which is the opposite byte
order to that of the VAX.

This means that "talk" packets sent out by the VAX are gibberish to the
HCX-7, and *vice versa*.

The "ntalk" version puts the data into a standard byte order before
sending it out on the wire.  Unfortunately, it still sends C structures
over the wire directly; fortunately, the structure *appears* to be laid
out so that the alignment and padding will be the same on most C
implementations where "short" is 2 bytes and "long" is 4 bytes.

If you FTPed the "talk" daemon from the "AT&T-free BSD stuff" on
"uunet", it's probably the 4.3BSD version.  As such, it stands at least
a fighting chance of, if successfully made to work on the HP and the
HCX-7, working compatibly on both those machines, as well as many other
machines on your network.

First, check whether either the HP or the Harris have an entry of the
form

	ntalk		518/udp

in "/etc/services".  If they do, they probably have the 4.3BSD version,
which I suspect might work between at least some set of different
machines.  If not, try to make the 4.3BSD version work on them, and if
you can do so, replace the native version with it.  (The 4.3BSD version
may depend on some 4.3BSD-isms that may not be present on the HP or the
Harris; you may have to tweak the code a bit for that.)  If *that*
doesn't work, the stuff pushed out on the wire may, in fact, still be
different; time to start digging and debugging.