```ruby
module WebDriver
  module Firefox
    class ExtensionConnection

      def initialize(host, port)
        @host = host
        @port = port
      end

      def connect(timeout = 20)
        Timeout.timeout(timeout) {
          loop do
            begin
              return new_socket
            rescue Errno::ECONNREFUSED => e
              $stderr.puts "#{self} caught #{e.message}" if $DEBUG
              sleep 0.250
            end
          end
        }
      end

      def new_socket
        @socket = TCPSocket.new(@host, @port)
        @socket.sync = true

        @socket
      end

      def connected?
        @socket && !@socket.closed?
      end

      def send_string(str)
        str = <<-HTTP
GET / HTTP/1.1
Host: localhost
Content-Length: #{str.length}

#{str}
HTTP
        @socket.write str
        @socket.flush
      end

      def quit
        command = {'commandName' => 'quit', 'context' => ''}
        send_string(command.to_json)
      ensure
        @socket.close
      end

      def close
        @socket.close
      end

      def read_response
        resp     = ""
        received = ""

        until resp.include?("\n\n")
          received = @socket.recv 1
          if received
            resp += received
          end
        end

        length      = resp.split(":")[1].lstrip!.to_i
        json_string = @socket.recv length

        JSON.parse json_string
      end

    end # ExtensionConnection
  end # Firefox
end # WebDriver
```

Raise a WebDriverError if the FF extension returns an empty reponse.
user
```ruby
module WebDriver
  module Firefox
    class ExtensionConnection

      def initialize(host, port)
        @host = host
        @port = port
      end

      def connect(timeout = 20)
        Timeout.timeout(timeout) {
          loop do
            begin
              return new_socket
            rescue Errno::ECONNREFUSED => e
              $stderr.puts "#{self} caught #{e.message}" if $DEBUG
              sleep 0.250
            end
          end
        }
      end

      def new_socket
        @socket = TCPSocket.new(@host, @port)
        @socket.sync = true

        @socket
      end

      def connected?
        @socket && !@socket.closed?
      end

      def send_string(str)
        str = <<-HTTP
GET / HTTP/1.1
Host: localhost
Content-Length: #{str.length}

#{str}
HTTP
        @socket.write str
        @socket.flush
      end

      def quit
        command = {'commandName' => 'quit', 'context' => ''}
        send_string(command.to_json)
      ensure
        @socket.close
      end

      def close
        @socket.close
      end

      def read_response
        resp     = ""
        received = ""

        until resp.include?("\n\n")
          received = @socket.recv 1
          if received
            resp += received
          end
        end

        length      = resp.split(":")[1].lstrip!.to_i
        json_string = @socket.recv length

        if json_string.empty?
          raise Error::WebDriverError, "empty response from extension"
        end

        JSON.parse json_string
      end

    end # ExtensionConnection
  end # Firefox
end # WebDriver
```
assistant