Add bin and edit workflow

bin/gems/eventmachine-1.2.7/lib/em/resolver.rb

@@ -0,0 +1,232 @@
+module EventMachine
+  module DNS
+    class Resolver
+
+      def self.windows?
+        if RUBY_PLATFORM =~ /mswin32|cygwin|mingw|bccwin/
+          require 'win32/resolv'
+          true
+        else
+          false
+        end
+      end
+
+      HOSTS_FILE = windows? ? Win32::Resolv.get_hosts_path : '/etc/hosts'
+
+      @hosts = nil
+      @nameservers = nil
+      @socket = nil
+
+      def self.resolve(hostname)
+        Request.new(socket, hostname)
+      end
+
+      def self.socket
+        if @socket && @socket.error?
+          @socket = Socket.open
+        else
+          @socket ||= Socket.open
+        end
+      end
+
+      def self.nameservers=(ns)
+        @nameservers = ns
+      end
+
+      def self.nameservers
+        return @nameservers if @nameservers
+
+        if windows?
+          _, ns = Win32::Resolv.get_resolv_info
+          return @nameservers = ns || []
+        end
+
+        @nameservers = []
+        IO.readlines('/etc/resolv.conf').each do |line|
+          if line =~ /^nameserver (.+)$/
+            @nameservers << $1.split(/\s+/).first
+          end
+        end
+
+        @nameservers
+      rescue
+        @nameservers = []
+      end
+
+      def self.nameserver
+        nameservers.shuffle.first
+      end
+
+      def self.hosts
+        return @hosts if @hosts
+
+        @hosts = {}
+        IO.readlines(HOSTS_FILE).each do |line|
+          next if line =~ /^#/
+          addr, host = line.split(/\s+/)
+
+          next unless addr && host
+          @hosts[host] ||= []
+          @hosts[host] << addr
+        end
+
+        @hosts
+      rescue
+        @hosts = {}
+      end
+    end
+
+    class RequestIdAlreadyUsed < RuntimeError; end
+
+    class Socket < EventMachine::Connection
+      def self.open
+        EventMachine::open_datagram_socket('0.0.0.0', 0, self)
+      end
+
+      def initialize
+        @nameserver = nil
+      end
+
+      def post_init
+        @requests = {}
+      end
+
+      def start_timer
+        @timer ||= EM.add_periodic_timer(0.1, &method(:tick))
+      end
+
+      def stop_timer
+        EM.cancel_timer(@timer)
+        @timer = nil
+      end
+
+      def unbind
+      end
+
+      def tick
+        @requests.each do |id,req|
+          req.tick
+        end
+      end
+
+      def register_request(id, req)
+        if @requests.has_key?(id)
+          raise RequestIdAlreadyUsed
+        else
+          @requests[id] = req
+        end
+
+        start_timer
+      end
+
+      def deregister_request(id, req)
+        @requests.delete(id)
+        stop_timer if @requests.length == 0
+      end
+
+      def send_packet(pkt)
+        send_datagram(pkt, nameserver, 53)
+      end
+
+      def nameserver=(ns)
+        @nameserver = ns
+      end
+
+      def nameserver
+        @nameserver || Resolver.nameserver
+      end
+
+      # Decodes the packet, looks for the request and passes the
+      # response over to the requester
+      def receive_data(data)
+        msg = nil
+        begin
+          msg = Resolv::DNS::Message.decode data
+        rescue
+        else
+          req = @requests[msg.id]
+          if req
+            @requests.delete(msg.id)
+            stop_timer if @requests.length == 0
+            req.receive_answer(msg)
+          end
+        end
+      end
+    end
+
+    class Request
+      include Deferrable
+      attr_accessor :retry_interval, :max_tries
+
+      def initialize(socket, hostname)
+        @socket = socket
+        @hostname = hostname
+        @tries = 0
+        @last_send = Time.at(0)
+        @retry_interval = 3
+        @max_tries = 5
+
+        if addrs = Resolver.hosts[hostname]
+          succeed addrs
+        else
+          EM.next_tick { tick }
+        end
+      end
+
+      def tick
+        # Break early if nothing to do
+        return if @last_send + @retry_interval > Time.now
+        if @tries < @max_tries
+          send
+        else
+          @socket.deregister_request(@id, self)
+          fail 'retries exceeded'
+        end
+      end
+
+      def receive_answer(msg)
+        addrs = []
+        msg.each_answer do |name,ttl,data|
+          if data.kind_of?(Resolv::DNS::Resource::IN::A) ||
+              data.kind_of?(Resolv::DNS::Resource::IN::AAAA)
+            addrs << data.address.to_s
+          end
+        end
+
+        if addrs.empty?
+          fail "rcode=#{msg.rcode}"
+        else
+          succeed addrs
+        end
+      end
+
+      private
+
+        def send
+          @tries += 1
+          @last_send = Time.now
+          @socket.send_packet(packet.encode)
+        end
+
+        def id
+          begin
+            @id = rand(65535)
+            @socket.register_request(@id, self)
+          rescue RequestIdAlreadyUsed
+            retry
+          end unless defined?(@id)
+
+          @id
+        end
+
+        def packet
+          msg = Resolv::DNS::Message.new
+          msg.id = id
+          msg.rd = 1
+          msg.add_question @hostname, Resolv::DNS::Resource::IN::A
+          msg
+        end
+
+    end
+  end
+end