added Utils::is_localhost and t/qpsmtpd-utils.t

resolves Issue #89

lib/Qpsmtpd.pm

@@ -591,7 +591,7 @@ sub spool_dir {
     unless ($Spool_dir) {    # first time through
         $self->log(LOGDEBUG, "Initializing spool_dir");
         $Spool_dir = $self->config('spool_dir')
-          || Qpsmtpd::Utils::tildeexp('~/tmp/');
+          || Qpsmtpd::Utils->tildeexp('~/tmp/');
 
         $Spool_dir .= "/" unless ($Spool_dir =~ m!/$!);
 

lib/Qpsmtpd/Utils.pm

@@ -2,7 +2,7 @@ package Qpsmtpd::Utils;
 use strict;
 
 sub tildeexp {
-    my $path = shift;
+    my ($self, $path) = @_;
     $path =~ s{^~([^/]*)} {  
 	  $1
 	      ? (getpwnam($1))[7] 
@@ -11,4 +11,13 @@ sub tildeexp {
     return $path;
 }
 
+sub is_localhost {
+    my ($self, $ip) = @_;
+    return if ! $ip;
+    return 1 if $ip =~ /^127\./;  # IPv4
+    return 1 if $ip =~ /:127\./;  # IPv4 mapped IPv6
+    return 1 if $ip eq '::1';     # IPv6
+    return;
+}
+
 1;

t/qpsmtpd-utils.t

@@ -0,0 +1,35 @@
+#!/usr/bin/perl
+use strict;
+use warnings;
+
+use Test::More;
+
+use lib 'lib';      # test lib/Qpsmtpd/Utils (vs site_perl)
+
+BEGIN { use_ok('Qpsmtpd::Utils'); }
+
+my $utils = bless {}, 'Qpsmtpd::Utils';
+
+__tildeexp();
+__is_localhost();
+
+done_testing();
+
+sub __is_localhost {
+
+    for my $local_ip (qw/ 127.0.0.1 ::1 2607:f060:b008:feed::127.0.0.1 127.0.0.2 /) {
+        ok( $utils->is_localhost($local_ip), "is_localhost, $local_ip");
+    }
+
+    for my $rem_ip (qw/ 128.0.0.1 ::2 2607:f060:b008:feed::128.0.0.1 /) {
+        ok( !$utils->is_localhost($rem_ip), "!is_localhost, $rem_ip");
+    }
+};
+
+sub __tildeexp {
+    my $path = $utils->tildeexp('~root/foo.txt');
+    ok( $path, "tildeexp, $path");
+
+    $path = $utils->tildeexp('no/tilde/in/path');
+    cmp_ok( $path, 'eq', 'no/tilde/in/path', 'tildeexp, no expansion');
+};