[#59] Arpnip tries to resolve link local IPv6 addresses

Netdisco/Changes

@@ -7,6 +7,7 @@
   [ENHANCEMENTS]
 
   * [#82] Check /etc/hosts before DNS when doing arp entry name lookup
+  * [#59] Arpnip tries to resolve link local IPv6 addresses 
 
   [BUG FIXES]
 

Netdisco/lib/App/Netdisco/Manual/Configuration.pod

@@ -761,12 +761,18 @@ Value: Settings Tree. Default:
 
  dns:
    max_outstanding: 250
+   no: ['fe80::/64','169.254.0.0/16']
 
-Sets the maximum number of outstanding requests for asynchronous DNS
-resolution used during arpnip and device alias discovery.
+Controls the asynchronous DNS resolver used to resolve IP addresses to
+names during arpnip and discovery of device aliases.
 
-This setting overrides the C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS> environment
-value and the C<AnyEvent> library default of 10.  
+C<max_outstanding> sets the maximum number of outstanding requests for
+asynchronous DNS resolution.  This setting overrides the
+C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS> environment value and the C<AnyEvent>
+library default of 10.
+
+C<no> is a list of IP addresses or CIDR ranges to excluded from DNS
+resolution.  Link local addresses are excluded by default.
 
 =head3 C<housekeeping>
 

Netdisco/lib/App/Netdisco/Util/DNS.pm

@@ -3,9 +3,11 @@ package App::Netdisco::Util::DNS;
 use strict;
 use warnings FATAL => 'all';
 
+use Dancer ':script';
 use Net::DNS;
 use AnyEvent::DNS::EtcHosts;
 use AnyEvent::DNS;
+use NetAddr::IP::Lite ':lower';
 
 use base 'Exporter';
 our @EXPORT = ();
@@ -104,6 +106,7 @@ sub hostnames_resolve_async {
 
   foreach my $hash_ref (@$ips) {
     my $ip = $hash_ref->{'ip'} || $hash_ref->{'alias'};
+    next if no_resolve($ip);
     $done->begin;
     AnyEvent::DNS::reverse_verify $ip,
             sub { $hash_ref->{'dns'} = shift; $done->end; };
@@ -118,5 +121,30 @@ sub hostnames_resolve_async {
   return $ips;
 }
 
+=head2 no_resolve( $ip )
+
+Given an IP address, returns true if excluded from DNS resolution by the
+C<dns_no> configuration directive, otherwise returns false.
+
+=cut
+
+sub no_resolve {
+    my $ip = shift;
+
+    my $config = setting('dns')->{no} || [];
+    return 0 if not scalar @$config;
+
+    my $addr = NetAddr::IP::Lite->new($ip);
+
+    foreach my $item (@$config) {
+        my $c_ip = NetAddr::IP::Lite->new($item)
+            or next;
+        next unless $c_ip->bits == $addr->bits;
+
+        return 1 if ($c_ip->contains($addr));
+    }
+    return 0;
+}
+
 1;
 

Netdisco/share/config.yml

@@ -158,6 +158,7 @@ workers:
 
 dns:
   max_outstanding: 250
+  no: ['fe80::/64','169.254.0.0/16']
 
 #housekeeping:
 #  discoverall: