1 files changed, 79 insertions, 0 deletions
diff --git a/lib/custodian/util/dns.rb b/lib/custodian/util/dns.rb
new file mode 100644
index 0000000..901dae0
--- /dev/null
+++ b/lib/custodian/util/dns.rb
@@ -0,0 +1,79 @@
+
+
+require 'ipaddr'
+require 'socket'
+require 'timeout'
+
+
+
+#
+#  This class is responsible for doing forward/reverse DNS lookups
+#
+module Custodian
+  module Util
+    class DNS
+
+
+      #
+      # Return the reverse DNS for the specified IP address, nil on failure.
+      #
+      def DNS.ip_to_hostname( ip )
+        resolved = nil
+        begin
+          timeout( 4 ) do
+            begin
+              Socket.getaddrinfo(ip, 'echo').each do |a|
+                resolved = a[2] if ( a )
+              end
+            rescue SocketError
+              resolved = nil
+            end
+          end
+        rescue Timeout::Error => e
+          resolved = nil
+        end
+        resolved
+      end
+
+
+      #
+      # Convert a hostname to an IP address, return nil on failure.
+      #
+      def DNS.hostname_to_ip( hostname )
+
+        resolved = nil
+
+        begin
+          timeout( 4 ) do
+            begin
+              Socket.getaddrinfo(hostname, 'echo').each do |a|
+                resolved = a[3] if ( a )
+              end
+            rescue SocketError
+              resolved = nil
+            end
+          end
+        rescue Timeout::Error => e
+          resolved = nil
+        end
+        resolved
+      end
+
+    end
+
+  end
+end
+
+
+
+
+if __FILE__ == $0 then
+
+  %w( ssh.steve.org.uk ipv6.steve.org.uk ).each do |name|
+    puts "Hostname test: #{name} #{Custodian::Util::DNS.hostname_to_ip(name) }"
+  end
+
+  %w( 80.68.85.46 80.68.85.48 2001:41c8:125:46::22 ).each do |name|
+    puts "Hostname test: #{name} #{Custodian::Util::DNS.ip_to_hostname(name) }"
+  end
+end