You may run this project using PHP's built-in web server for local development.
git clone https://github.com/php/web-news.git
cd web-news/
NNTP_HOST=news.php.net php -S localhost:8080 .router.php
this is all very ugly. just proof-of-concept, really.
the biggest thing to do would be to do something smart with mime-encoded messages. but keeping the current property of not slurping the whole damn message into memory just to do so.
another thing to do would be to support posting. to avoid completely anonymous posting, this could require confirming the email address before allowing posts. to do this without actually having to maintain a database of users, we could send an email containing md5(md5("email:timestamp").$secret) (where $secret is some value that is kept secret. duh.) and then let the user "log in" by supplying their email address and this code, and storing that in a cookie. depends on a secret for 'security', but like i said, it avoids having to maintain any sort of state on the server side. blocking email addresses for posting will be easy enough if anyone ever abuses the system.
should also probably protect email addresses from harvesters. then again, anyone who wanted to harvest email addresses could just crawl the nntp server directly. or they can crawl any of the other mail archives that don't protect the addresses.
keeping track of a .newsrc-like state for users would be cool, too. too bad there's no Set::IntSpan for php.
perhaps chasing up the references: chain to display the thread when displaying an article would be interesting. i have a feeling that building some sort of index is going to be desirable at some point. should use jwz's threading algorithm. http://www.jwz.org/doc/threading.html
ftp://ftp.isi.edu/in-notes/rfc2047.txt explains how to decode encoded header fields. handling utf-8 and iso-8859-1 should be pretty easy. could use the gnu recode functions to do this in a general way, i think.
oh, and this uses direct socket functions instead of the php imap extension because nntp is a drop-dead-easy protocol, and i'm allergic to the c-client code.
SC.2004.09.03: Here are the appropriate Rewrite rules for apache:
RewriteEngine on
RewriteRule ^/(php.+)/start/([0-9]+) /group.php?group=$1&i=$2 [L]
RewriteRule ^/(php.+)/([0-9]+) /article.php?group=$1&article=$2 [L]
RewriteRule ^/(php[^/]+)(/)?$ /group.php?group=$1 [L]