#!/usr/bin/perl -w
use strict;
use LWP::Simple;

use vars qw($in_file @imgdata @imgs 
            $num     $id      $image 
            $url     $type    $format
            $out_file);
$in_file = 'ads.dat';

@imgdata = <DATA>;

@imgs = grep {/\|(?:internal|partner)$/} @imgdata;

$num = int(rand($#imgs) +1);

($id, $image, $url, $type) = split /\|/, $imgs[$num];

$url = $url . $image;
$format = $1 if $image =~ /\.(\w+)$/;
$format = 'jpeg' if $format =~ /^jpe?g$/;

$out_file  = get($url);
print "Content-type: image/$format\n\n";
print $out_file;

__DATA__
1|/images/dibona_sm.gif|http://perlmonks.org|internal
2|/images/usermonkpics/ovidmonk.gif|http://perlmonks.org|partner
3|/pics/gol.gif|http://www.f.com|payed

##</code><code>##

<img src="http://www.somedomain.com/cgi-bin/myscriptname.cgi" alt="Random image">