Internally, CGI.pm uses the URI module to parse a uri. I'd use the query_form method to parse each line of the log file. Something like this:

use URI;

my $u = URI->new("http://perlmonks.org/index.pl?node_id=164782&abc=123
+");
my @param = $u->query_form();
foreach (@param) {
    print "$_\n";
}
[download]

output:

C:\S>perl uritest.pl
node_id
164782
abc
123
[download]