New system specific code for resolving nameservers and hosts (configuration).

Author: ioquatix

lib/rubydns/system.rb

@@ -0,0 +1,146 @@
+# Copyright (c) 2009, 2011 Samuel G. D. Williams. <http://www.oriontransfer.co.nz>
+# 
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+# 
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+# 
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
+begin
+require 'win32/resolv'
+rescue LoadError
+# Ignore this - we aren't running on windows.
+end
+
+module RubyDNS
+# This module encapsulates system dependent name lookup functionality.
+module System
+RESOLV_CONF = "/etc/resolv.conf"
+HOSTS = "/etc/hosts"
+
+def self.hosts_path
+if RUBY_PLATFORM =~ /mswin32|mingw|bccwin/
+Win32::Resolv.get_hosts_path
+else
+HOSTS
+end
+end
+
+# This code is very experimental
+class Hosts
+def initialize
+@addresses = {}
+@names = {}
+end
+
+attr :addresses
+attr :names
+
+# This is used to match names against the list of known hosts:
+def call(name)
+@names.include?(name)
+end
+
+def lookup(name)
+addresses = @names[name]
+
+if addresses
+addresses.last
+else
+nil
+end
+end
+
+alias [] lookup
+
+def add(address, names)
+@addresses[address] ||= []
+@addresses[address] += names
+
+names.each do |name|
+@names[name] ||= []
+@names[name] << address
+end
+end
+
+def parse_hosts(io)
+io.each do |line|
+line.sub!(/#.*/, '')
+address, hostname, *aliases = line.split(/\s+/)
+
+add(address, [hostname] + aliases)
+end
+end
+
+def self.local
+hosts = self.new
+
+path = System::hosts_path
+
+if path and File.exist?(path)
+File.open(path) do |file|
+hosts.parse_hosts(file)
+end
+end
+
+return hosts
+end
+end
+
+def self.parse_resolv_configuration(path)
+nameservers = []
+File.open(path) do |file|
+file.each do |line|
+# Remove any comments:
+line.sub!(/[#;].*/, '')
+
+# Extract resolv.conf command:
+keyword, *args = line.split(/\s+/)
+
+case keyword
+when 'nameserver'
+nameservers += args
+end
+end
+end
+
+return nameservers
+end
+
+def self.standard_connections(nameservers)
+connections = []
+
+nameservers.each do |host|
+connections << [:udp, host, 53]
+connections << [:tcp, host, 53]
+end
+
+return connections
+end
+
+# Get a list of standard nameserver connections which can be used for querying any standard servers that the system has been configured with. There is no equivalent facility to use the `hosts` file at present.
+def self.nameservers
+nameservers = []
+
+if File.exist? RESOLV_CONF
+nameservers = parse_resolv_configuration(RESOLV_CONF)
+elsif defined?(Win32::Resolv) and RUBY_PLATFORM =~ /mswin32|cygwin|mingw|bccwin/
+search, nameservers = Win32::Resolv.get_resolv_info
+end
+
+return standard_connections(nameservers)
+end
+end
+end