tinyleaf miniature transit news server
rra at stanford.edu
Sun Apr 10 07:40:58 UTC 2005
As previously discussed on the list some time ago, I've added tinyleaf to
the INN distribution. This is a minimal transit news server that
essentially runs a single channel feed and is useful for processing
incoming messages with a script without needing to run a full-blown news
Here is the documentation:
tinyleaf - Very simple IHAVE-only NNTP server
tinyleaf *spool* [*processor*]
tinyleaf is intended to be the simplest possible transit news server
that still does something useful. It must be run under inetd(8) or some
equivalent, and only implements three commands (IHAVE, HELP, and QUIT).
When it receives an article, it saves it into the directory *spool* and,
if *processor* is given, passes information about the article to
*processor* via a pipe. The file name of the article will be the MD5
hash of its message ID, and if a file by that name already exists,
tinyleaf will refuse the article, reporting it as a duplicate.
If *processor* is given, it should specify the path to a program. That
program is started when tinyleaf starts, and its current working
directory will be *spool*. For each article received by tinyleaf, a
single line will be sent to standard input of *processor*. That line
will consist of the file name of the received article (relative to
*spool*), a single space, and the message ID of the received article.
Note that the message ID will be taken from the argument to the IHAVE
command and may not match the Message-ID header in the article. When
tinyleaf shuts down, standard input to *processor* will be closed.
tinyleaf does no syntax verification of received articles whatsoever; it
just stores them and optionally passes them off to *processor*. It also
never deletes articles; normally, *processor* should do that when it's
finished doing whatever it needs to with the article.
tinyleaf expects NNTP commands on standard input and replies on standard
output. Status information and any error messages are sent to standard
error. It does no authentication; any authentication must be done by
inetd(8) or by a wrapper program. (One simple authentication mechanism
is to invoke tinyleaf via tcpd(8) from TCP wrappers and use
/etc/hosts.allow and /etc/hosts.deny to restrict who can talk to the
tinyleaf has a (currently hard-coded) maximum message size of 1MB and a
(similarly hard-coded) timeout of ten minutes for each command or chunk
of article data.
Suppose that you want to archive news articles on a particular host
(like the FTP server for a newsgroup archive) where you don't want the
overhead of running a full-blown news server. Write a program that reads
one line at a time from standard input and treats everything before the
first space as the filename of a news article to archive. Each time the
program reads a line, it should archive that file and then delete it,
and it should exit when it gets end of file on standard input.
Then, add a line like:
nntp stream tcp nowait archive /usr/sbin/tcpd \
/usr/local/bin/tinyleaf /var/spool/tinyleaf /usr/local/bin/archive
(all on one line -- the backslash and split in this line is just for
readability) where "archive" is the user that owns the archive,
"/usr/sbin/tcpd" is the path to tcpd(8), "/usr/local/bin/tinyleaf" is
the path to this program, /var/spool/tinyleaf is some scratch directory
that the user "archive" has write access to, and
"/usr/local/bin/archive" is the path to your archive script.
You can now restrict access to tinyleaf to just your local news server
with "/etc/hosts.allow" and "/etc/hosts.deny" and set up an ordinary
feed from the server to the archive host, just like you would to any
other news server, of only the newsgroup that you want to archive.
Note that the archiving script should probably perform basic syntax and
validity checks on the input, since tinyleaf doesn't.
This is the application that motivated the original development of this
The timeout and maximum message size should really be configurable.
tinyleaf should also probably not just respond 500 to every command
other than IHAVE, HELP, and QUIT; there are more useful (and more
expected) error codes that could be returned.
An option to scan the spool directory for any left-over files and pass
them to the processor when starting up would be useful.
Written by Russ Allbery <rra at stanford.edu> for InterNetNews.
$Id: tinyleaf.pod,v 1.1 2005/04/10 07:39:12 rra Exp $
hosts_access(5), inetd(8), tcpd(8).
Russ Allbery (rra at stanford.edu) <http://www.eyrie.org/~eagle/>
Please send questions to the list rather than mailing me directly.
<http://www.eyrie.org/~eagle/faqs/questions.html> explains why.
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