Your problem in in this line:

my (%hash, $conf) = @_;

List assignment is greedy. So the hash takes all of @_ leaving nothing to go into $conf. If you had "use warnings" turned on then you'd get the error about using a list with an odd number of elements to create a hash.

There are (at least) three solutions:

1. Pass the parameters the other way round.

my ($conf, %hash) = @_;

2. Use "pop" to get $conf.

my $conf = pop @_;
my $hash = @_;
[download]

3. Pass in a hash reference instead of the hash.

my ($hash_ref, $conf) = @_;