vagrant-hostmanager/lib/vagrant-hostmanager/hosts_file.rb

require 'tempfile'

module VagrantPlugins
  module HostManager
    module HostsFile
      def update_guest(machine)
        return unless machine.communicate.ready?

        if (machine.communicate.test("uname -s | grep SunOS"))
          realhostfile = '/etc/inet/hosts'
          move_cmd = 'mv'
        elsif (machine.communicate.test("test -d $Env:SystemRoot"))
          realhostfile = "#{ENV['WINDIR']}\\System32\\drivers\\etc\\hosts"
          move_cmd = 'mv -force'
        else 
          realhostfile = '/etc/hosts'
          move_cmd = 'mv'
        end
        # download and modify file with Vagrant-managed entries
        file = @global_env.tmp_path.join("hosts.#{machine.name}")
        machine.communicate.download(realhostfile, file)
        if update_file(file, machine, false)

          # upload modified file and remove temporary file
          machine.communicate.upload(file, '/tmp/hosts')
          machine.communicate.sudo("#{move_cmd} /tmp/hosts #{realhostfile}")
        end

        # i have no idea if this is a windows competibility issue or not, but sometimes it dosen't work on my machine
        begin
          FileUtils.rm(file) 
        rescue Exception => e
        end
      end

      def update_host
        # copy and modify hosts file on host with Vagrant-managed entries
        file = @global_env.tmp_path.join('hosts.local')

        if WindowsSupport.windows?
          # lazily include windows Module
          class << self
            include WindowsSupport unless include? WindowsSupport
          end

          hosts_location = "#{ENV['WINDIR']}\\System32\\drivers\\etc\\hosts"
          copy_proc = Proc.new { windows_copy_file(file, hosts_location) }
        else
          hosts_location = '/etc/hosts'
          copy_proc = Proc.new { `sudo cp #{file} #{hosts_location}` }
        end

        FileUtils.cp(hosts_location, file)
        if update_file(file)
          copy_proc.call
        end
      end

      private

      def update_file(file, resolving_machine = nil, include_id = true)
        file = Pathname.new(file)
        old_file_content = file.read
        new_file_content = update_content(old_file_content, resolving_machine, include_id)
        file.open('w') { |io| io.write(new_file_content) }
        old_file_content != new_file_content
      end

      def update_content(file_content, resolving_machine, include_id)
        id = include_id ? " id: #{read_or_create_id}" : ""
        header = "## vagrant-hostmanager-start#{id}\n"
        footer = "## vagrant-hostmanager-end\n"
        body = get_machines
          .map { |machine| get_hosts_file_entry(machine, resolving_machine) }
          .join
        get_new_content(header, footer, body, file_content) 
      end

      def get_hosts_file_entry(machine, resolving_machine)
        ip = get_ip_address(machine, resolving_machine)
        host = machine.config.vm.hostname || machine.name
        aliases = machine.config.hostmanager.aliases.join(' ').chomp
        "#{ip}\t#{host} #{aliases}\n"
      end

      def get_ip_address(machine, resolving_machine)
        custom_ip_resolver = machine.config.hostmanager.ip_resolver
        if custom_ip_resolver
          custom_ip_resolver.call(machine, resolving_machine)
        else
          ip = nil
          if machine.config.hostmanager.ignore_private_ip != true
            machine.config.vm.networks.each do |network|
              key, options = network[0], network[1]
              ip = options[:ip] if key == :private_network
              break if ip
            end
          end
          ip || (machine.ssh_info ? machine.ssh_info[:host] : nil)
        end
      end

      def get_machines
        if @config.hostmanager.include_offline?
          machines = @global_env.machine_names
        else
          machines = @global_env.active_machines
            .select { |name, provider| provider == @provider }
            .collect { |name, provider| name }
        end
        # Collect only machines that exist for the current provider
        machines.collect do |name|
              begin
                machine = @global_env.machine(name, @provider)
              rescue Vagrant::Errors::MachineNotFound
                # ignore
              end
              machine
            end
          .reject(&:nil?)
      end

      def get_new_content(header, footer, body, old_content)
        if body.empty?
          block = "\n"
        else
          block = "\n\n" + header + body + footer + "\n"
        end
        # Pattern for finding existing block
        header_pattern = Regexp.quote(header)
        footer_pattern = Regexp.quote(footer)
        pattern = Regexp.new("\n*#{header_pattern}.*?#{footer_pattern}\n*", Regexp::MULTILINE)
        # Replace existing block or append
        old_content.match(pattern) ? old_content.sub(pattern, block) : old_content.rstrip + block
      end

      def read_or_create_id
        file = Pathname.new("#{@global_env.local_data_path}/hostmanager/id")
        if (file.file?)
          id = file.read.strip
        else
          id = SecureRandom.uuid
          file.dirname.mkpath
          file.open('w') { |io| io.write(id) }
        end
        id
      end

      ## Windows support for copying files, requesting elevated privileges if necessary
      module WindowsSupport
        require 'rbconfig'

        def self.windows?
          RbConfig::CONFIG['host_os'] =~ /mswin|mingw|cygwin/
        end

        require 'win32ole' if windows?

        def windows_copy_file(source, dest)
          begin
            # First, try Ruby copy
            FileUtils.cp(source, dest)
          rescue Errno::EACCES
            # Access denied, try with elevated privileges
            windows_copy_file_elevated(source, dest)
          end
        end

        private 

        def windows_copy_file_elevated(source, dest)
          # copy command only supports backslashes as separators
          source, dest = [source, dest].map { |s| s.to_s.gsub(/\//, '\\') }
          
          # run 'cmd /C copy ...' with elevated privilege, minimized
          copy_cmd = "copy \"#{source}\" \"#{dest}\""        
          WIN32OLE.new('Shell.Application').ShellExecute('cmd', "/C #{copy_cmd}", nil, 'runas', 7)

          # Unfortunately, ShellExecute does not give us a status code,
          # and it is non-blocking so we can't reliably compare the file contents
          # to see if they were copied.
          #
          # If the user rejects the UAC prompt, vagrant will silently continue 
          # without updating the hostsfile.
        end
      end
    end
  end
end