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-rw-r--r--lib/custodian/dnsutil.rb72
1 files changed, 72 insertions, 0 deletions
diff --git a/lib/custodian/dnsutil.rb b/lib/custodian/dnsutil.rb
new file mode 100644
index 0000000..e42d5e3
--- /dev/null
+++ b/lib/custodian/dnsutil.rb
@@ -0,0 +1,72 @@
+
+
+require 'ipaddr'
+require 'socket'
+require 'timeout'
+
+
+
+#
+# This class is responsible for doing forward/reverse DNS lookups
+#
+class DNSUtil
+
+
+ #
+ # Return the reverse DNS for the specified IP address, nil on failure.
+ #
+ def DNSUtil.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 DNSUtil.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
+
+
+if __FILE__ == $0 then
+
+ %w( ssh.steve.org.uk ipv6.steve.org.uk ).each do |name|
+ puts "Hostname test: #{name} #{DNSUtil.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} #{DNSUtil.ip_to_hostname(name) }"
+ end
+end