Use a common method of reading lines

Adds comment support for domain lists.

make-block.pl

@@ -25,13 +25,7 @@ my $dupes = 0;
 my $skip = 0;
 sub add_domain_list {
     my $file = shift;
-
-    open my $fni, '<', $file
-        or die "Failed to open file $file for reading: $!";
-
-    foreach my $line (<$fni>) {
-        chomp $line;
-        $line =~ s/^\s+|\s+$//;
+    foreach my $line (&read_stripped($file)) {
         my $domain = lc $line;
         ++$dupes if defined $domains{$domain};
         $domains{$domain} = 1;
@@ -40,15 +34,7 @@ sub add_domain_list {
 
 sub add_host_file {
     my $file = shift;
-
-    open my $fni, '<', $file
-        or die "Failed to open file $file for reading: $!";
-
-    foreach my $line (<$fni>) {
-        chomp $line;
-        # strip whitespace and comments
-        $line =~ s/^\s+|\s+$|\s*#.*$//;
-        next unless $line;
+    foreach my $line (&read_stripped($file)) {
         my @parts = split /\s+/, $line;
         die "Malformed line in $file: $line; @parts"
             unless @parts > 1;
@@ -66,6 +52,20 @@ sub add_host_file {
     }
 }
 
+sub read_stripped {
+    my $file = shift;
+
+    open my $fni, '<', $file
+        or die "Failed to open file $file for reading: $!";
+
+    map {
+        chomp;
+        # Strip whitespace and comments
+        s/^\s+|\s+$|\s*#.*$//;
+        $_ || ()
+    } <$fni>;
+}
+
 MAIN: {
     my $out;
     my $block_ip = '0.0.0.0 ::1';