class MQTT::Packet::Connect

def encode_body
  body = ''
  if @version == '3.1.0'
    raise 'Client identifier too short while serialising packet' if @client_id.nil? || @client_id.bytesize < 1
    raise 'Client identifier too long when serialising packet' if @client_id.bytesize > 23
  end
  body += encode_string(@protocol_name)
  body += encode_bytes(@protocol_level.to_i)
  if @keep_alive < 0
    raise 'Invalid keep-alive value: cannot be less than 0'
  end
  # Set the Connect flags
  @connect_flags = 0
  @connect_flags |= 0x02 if @clean_session
  @connect_flags |= 0x04 unless @will_topic.nil?
  @connect_flags |= ((@will_qos & 0x03) << 3)
  @connect_flags |= 0x20 if @will_retain
  @connect_flags |= 0x40 unless @password.nil?
  @connect_flags |= 0x80 unless @username.nil?
  body += encode_bytes(@connect_flags)
  body += encode_short(@keep_alive)
  body += encode_string(@client_id)
  unless will_topic.nil?
    body += encode_string(@will_topic)
    # The MQTT v3.1 specification says that the payload is a UTF-8 string
    body += encode_string(@will_payload)
  end
  body += encode_string(@username) unless @username.nil?
  body += encode_string(@password) unless @password.nil?
  body
end