Have a look at Net::LDAP. The code will look something like:

use strict;
use Net::LDAP;
my $ldap = Net::LDAP->new($ldaphost);

my $result = $ldap->search( base=>$groupdn,filter=>'(objectclass=*)',a
+ttrs=>['member']);

if ($result->code)
{
  print $result->error."\n";
  exit 1;
}

my $entry = $result->entry;
my @members = $entry->get('member');
[download]

Warning: Not tested.

Update: added an error check.