NNTP daemon -- DECWRL mods
Paul Vixie <vixie@nsl.dec.com> 17 August 1991 (cleaned up, sniffing sigpipes)
Paul Vixie <vixie@wrl.dec.com> 13 February 1991 (ported to 1.5.11, w/ leres)
Paul Vixie <vixie@wrl.dec.com> 04 October 1990 (improved by Steve Schoch)
Paul Vixie <vixie@wrl.dec.com> 18 September 1990 (improved by ken@sdd.hp.com)
Paul Vixie <vixie@wrl.dec.com> 16 June 1990 (works on 1.5.8)

These modifications add a "message ID daemon" to nntpd.  Nntpd will query
this daemon about all offered message ID's, and the daemon will keep a
managed, memory resident list of recent ID's.  "Recent" means ID's offered
within the last N (~1440, or one full day) minutes.  If an ID has been
inquired of in the last N minutes, the daemon says "don't accept it", which
keeps nntpd from accepting things that have already been accepted but which
are sitting in the input batch queue, waiting to be unbatched.  This whole
scheme is obviously only useful if you run C News, since nntp-for-B-News
just forks inews once per incoming article.

Installation is hopefully trivial.  Rebuild and reinstall nntpd with
these diffs applied; install msgidd as well; add this line to rc.local,
and execute it by hand (or reboot):

echo /usr/lib/news/etc/msgidd \
	-s /usr/lib/news/nntp_msgid \
	-l /usr/lib/news/msgid.log \
	-h 1440 "&" | su news >/dev/console

Note that /usr/lib/news/etc is where I keep nntpd and msgidd, and that
/usr/lib/news/nntp_msgid is the unix-domain socket used for the daemon.

Future enhancements:
	-> move all the dbz stuff out of ihave.c and just do it all here;
	   this will serialize the dbz reads into this one process, which
	   is debatable and needs more thought.

Thanks to ken@sdd.hp.com for:
	-> change the protocol so that requesting ID status
	   doesn't have the side effect of marking the article
	   as "received".  Marking it as received shouldn't be
	   done until the article has actually been written to
	   the batch file.

Thanks to Steve Schoch for:
	-> handle SIGPIPE properly, it's pretty common and I was
	   just SIG_IGN'ing it.

Thanks to James Brister for:
	-> msgidd.pid file, useful for SIGHUP'ing for logfile changes
