It seems quite simple, if I understand you right, you want to filter out values that don't begin with http://www.localhost.net or /.

Maybe this is what you need?

#!/usr/bin/perl -Wl
use strict;

my $my_domain = quotemeta 'http://www.localhost.net';

print for grep /^(?:$my_domain|\/)/, 
          qw[ /sered/uplink /my/projects/ heh/reg http://www.OtherNetw
+ork.org/network/ http://www.localhost.net/hello ];
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