tinyleaf miniature transit news server

[Russ Allbery]

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
server.

Here is the documentation:

NAME
    tinyleaf - Very simple IHAVE-only NNTP server

SYNOPSIS
    tinyleaf *spool* [*processor*]

DESCRIPTION
    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
    server.)

    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.

EXAMPLE
    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
    program.

BUGS
    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.

HISTORY
    Written by Russ Allbery <rra at stanford.edu> for InterNetNews.

    $Id: tinyleaf.pod,v 1.1 2005/04/10 07:39:12 rra Exp $

SEE ALSO
    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.