Module: MockDnsServer::MessageHelper

Defined in:
lib/mock_dns_server/message_helper.rb

Constant Summary collapse

MESSAGE_LENGTH_PACK_UNPACK_FORMAT = 
'n'

Class Method Summary collapse

Class Method Details

.convertible_to_dnsruby_message?(object) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/mock_dns_server/message_helper.rb', line 24

def self.convertible_to_dnsruby_message?(object)
  to_dns_message(object).is_a?(Dnsruby::Message)
end

.read_tcp_message(socket) ⇒ Object

Reads a message from a TCP connection. First gets the 2 byte length, then reads the payload. Attempts to convert the payload into a Dnsruby::Message.



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# File 'lib/mock_dns_server/message_helper.rb', line 54

def self.read_tcp_message(socket)

  message_len_str = socket.read(2)
  raise "Unable to read from socket; read returned nil" if message_len_str.nil?
  message_len = message_len_str.unpack(MESSAGE_LENGTH_PACK_UNPACK_FORMAT).first

  bytes_not_yet_read = message_len
  message_wire_data = ''

  while bytes_not_yet_read > 0
    str = socket.read(bytes_not_yet_read)
    bytes_not_yet_read -= str.size
    message_wire_data << str
  end

  message = MessageHelper.to_dns_message(message_wire_data)
  message
end

.send_udp_and_get_response(message, host, port) ⇒ Object

Sends a UDP message and returns the response, using a temporary socket.



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# File 'lib/mock_dns_server/message_helper.rb', line 75

def self.send_udp_and_get_response(message, host, port)
  socket = UDPSocket.new
  message = message.encode if message.is_a?(Dnsruby::Message)
  socket.send(message, 0, host, port)
  _, _, _ = IO.select([socket], nil, nil)
  response_data, _ = socket.recvfrom(10_000)
  response = to_dns_message(response_data)
  socket.close
  response
end

.tcp_message_package_for_write(message) ⇒ Object

Builds a string for a TCP client to send to a DNS server

Parameters:

  • message, —

    either a DNS message or a string

Returns:

  • if message is a Dnsruby::Message, returns the wire_data prepended with the 2-byte size field else returns the message unchanged



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# File 'lib/mock_dns_server/message_helper.rb', line 35

def self.tcp_message_package_for_write(message)
  message = message.encode if message.is_a?(Dnsruby::Message)
  size_field = [message.size].pack(MESSAGE_LENGTH_PACK_UNPACK_FORMAT)
  size_field + message
end

.to_dns_message(object) ⇒ Object

If the string can convert to a Dnsruby::Message without throwing an exception, return the Dnsruby::Message instance; else, return the original string.



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# File 'lib/mock_dns_server/message_helper.rb', line 10

def self.to_dns_message(object)
  case object
    when String
      begin
        Dnsruby::Message.decode(object)
      rescue
        object
      end
    when Dnsruby::Message
      object
  end
end

.udp_message_package_for_write(object) ⇒ Object 



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# File 'lib/mock_dns_server/message_helper.rb', line 42

def self.udp_message_package_for_write(object)
  case object
    when Dnsruby::Message
      object.encode
    when String
      object
  end
end