Add cidr2iface func

Change-Id: I8260923effdaa3c214aa02db36a750d373b120db

lib/puppet/parser/functions/cidr2iface.rb

@@ -0,0 +1,31 @@
+#    Copyright 2015 Midokura SARL, Inc.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+require 'netaddr'
+require 'socket'
+
+module Puppet::Parser::Functions
+  newfunction(:cidr2iface, :type => :rvalue, :doc => <<-EOS
+    This function returns a iface name or will raise an error if no iface matches
+    EOS
+  ) do |argv|
+    unless argv[0] =~ /^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\/[0-9]{,2}$/
+      raise ArgumentError, "#{argv[0]} is not a valid CIDR"
+    end
+    ifaces = Socket.getifaddrs.map { |i| {ip: i.addr.ip_address,name: i.name,cidr: NetAddr::CIDR::create("#{i.addr.ip_address} #{i.netmask.ip_address}").to_s } if i.addr.ipv4? }.compact
+    matching_iface = ifaces.select{ |i| i[:cidr] == argv[0]}.first
+    return matching_iface[:name] unless matching_ifaces.nil?
+    raise ("No Matching iface found")
+  end
+end