Redirect ubuntu archive requests to another mirror when using squid as an apt proxy (or transparent proxy)

rewrite.pl

#!/usr/bin/perl
#
# url_rewrite_program /etc/squid/rewrite.pl
# add ^^^ to your squid.conf
#

$mirror = "example.com";

$| = 1;
while (<>) {
    @line = split;
    $_ = $line[0];
    if (m/^http:\/\/((?:[a-z0-9]+\.)?archive\.ubuntu\.com)\/(.*)/ &&
        $1 ne $mirror) {
        print "http://" . $mirror . "/" . $2 . "\n";
    } else {
        print $_ . "\n";
    }
}