# Blosxom Plugin: deferer
# Author: Jason Clark (http://jclark.org/weblog/);
# Version 0+2i
# Blosxom Home/Docs/Licensing: http://www.blosxom.com
# deferer plugin Home/Docs/Licensing: 
#     http://jclark.org/weblog/WebDev/Blosxom/plugins/deferer

package deferer;

# ----- Configuration Variables -----

# The IP Address in question
$ip = '161.58.59.8';

# -----------------------------------

sub start {
    package blosxom;
    use Socket;

    my $refer = referer();
    if ($refer =~ m!https?://!) {
	my $r = (split(/\//, $refer))[2];
	my $n = inet_aton($r);
	if (defined $n && inet_ntoa($n) eq $deferer::ip) {
	    print STDERR "Redirected $r\n";
	    print "Status: 301 Moved Permanently\n";
	    print "Location: $refer\n\n";
	    exit(0);
	}
    }
    1;
}

1;

__END__

=head1 Name

Blosxom Plug-In: defer

=head1 Synopsis

A bit of defense against a particularly tenacious referer spammer.  A one-trick pony
for now, but eventually will get expanded to combat other sorts of referer spam (as 
time permits).

=head1 Quick Start

Just drop it in your $plugin_dir.  There is only one config variable, which 
you shouldn't need to change, at least until this jerk gets chased to another
hosting provider with another IP.

Deferer tries to save your server a few cycles by ending the entire blosxom run (via 
exit(0)) once a redirect header has been sent.  To save the most time, make this plugin
run first by naming it 00deferer.

=head1 More Info

For lots more info, see the SEE ALSO section below.
  
In a nutshell, tons of referer spam is currently being sent out with
hundreds of refer'ed URIs.  They all resolve to one IP address - 161.58.59.8.  When visited,
they all show a fake 'hosting account suspended' message.  Days later the sites come on line
with live links to poker sites and other junk.  Same rig is sending tons of comment spam
using info harvested previously.

The traffic comes through many proxies and zombie machines, so instead of checking the 
remote ip, we block anyone using one of the referers.  Because we can, we send a redirect 
right back to the offending URL.  Let 'em waste their own bandwith.

=head1 Version

0+2i

=head1 Changelog

0+2i:
  * fixed bug that caused 500 server error if referer could not be resolved

0+1i: 
  * original release

=head1 Author

Jason Clark  (jason@jclark.org; http://jclark.org/weblog)

=head1 Acknowledgements

Credit for the idea, as well as inspirational PHP code, goes to John Sinteur who
wrote about this on the Wordpress Support blog: 
  http://wordpress.org/support/topic.php?id=20956#post-119138

=head1 See Also

Info on the problem:
  http://wordpress.org/support/topic.php?id=20956#post-119138
  http://www.tbray.org/ongoing/When/200x/2005/01/16/RefererBS
  http://virtuelvis.com/archives/2005/01/referer_spammers_are_comment_spammers_too
  http://www.annelisabeth.com/blog/archives/000165.html (and many other enties on Anne's site)

Blosxom Home/Docs/Licensing: 
  http://www.blosxom.com/

Blosxom Plugin Docs: 
  http://www.blosxom.com/documentation/users/plugins.html

deferer plugin Home/Docs/Licensing: 
  http://jclark.org/weblog/WebDev/Blosxom/plugins/deferer

=head1 Bugs

I wouldn't be surprised.

Not tested at all with static rendering, not really applicable.

=head1 License

This Blosxom Plug-in Copyright 2005, Jason Clark

(This license is the same as Blosxom's)
Permission is hereby granted, free of charge, to any person obtaining a copy 
of this software and associated documentation files (the "Software"), to deal 
in the Software without restriction, including without limitation the rights 
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
copies of the Software, and to permit persons to whom the Software is furnished 
to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all 
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS 
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR 
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER 
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.