def treat_data_from_receive(self, data):
try:
sender = socket.socket(AF_INET, SOCK_DGRAM)
sender.connect((self._next_dns_addr, self._port))
sender.settimeout(5)
sender.send(data)
data = sender.recv(1024)
sender.close()
except socket.error:
answer = MessageParser.to_bytes(
self._message_parser.transaction_id,
MessageType.QUERY,
self._message_parser.opcode,
HaveStatus.NO,
self._message_parser.recursion_required,
self._message_parser.recursion_available,
RCode.REFUSED,
self._message_parser.message[12:],
answers_num=0,
answers=[])
self._dns_listener.sendto(answer, self._client_addr)
return
self._dns_listener.sendto(data, self._client_addr)
answer_info = MessageParser()
answer_info.from_bytes(data)
for container in [
answer_info.answers, answer_info.resources_rights,
answer_info.additional_resources
]:
for resource in container:
self._cache.add_record(resource.ttl, resource.name.decode(),
resource.resource_type,
resource.resource_data,
resource.resource_class)
self._client_addr = None
class Resolver:
def __init__(self, next_dns_addr, cash_file_name='cache.txt'):
self._port = 53
self._cache = Cache(cash_file_name)
self._dns_listener = Resolver.bind_server()
self._next_dns_addr = next_dns_addr
self._message_parser = MessageParser()
self._client_addr = None
@staticmethod
def bind_server(addr='localhost', port=53):
server = socket.socket(AF_INET, SOCK_DGRAM)
server.bind((addr, port))
return server
def on_press(self, key):
try:
k = key.char
if k == 'c':
self._dns_listener.close()
except:
pass
def try_find_info(self, query, answers):
new_answers = []
domain_addr = query.name.decode()
for record in self._cache.records:
if domain_addr == record.address and query.query_type == record.resource_type:
new_answers.append(record)
answers.extend(new_answers)
return len(new_answers) > 0
def start_listening(self):
lis = keyboard.Listener(on_press=self.on_press)
lis.start()
try:
while True:
self._message_parser = MessageParser()
self._cache.update_cache()
data, self._client_addr = self._dns_listener.recvfrom(1024)
self._message_parser.from_bytes(data)
have_all_data = True
answers = []
for query in self._message_parser.queries:
have_info = self.try_find_info(query, answers)
if query.query_type == ResourceType.PTR and\
self._message_parser.questions_num > 1:
continue
elif not have_info:
self.treat_data_from_receive(data)
have_all_data = False
break
if have_all_data and len(answers) > 0:
answer = MessageParser.to_bytes(
self._message_parser.transaction_id,
MessageType.ANSWER,
self._message_parser.opcode,
HaveStatus.NO,
self._message_parser.recursion_required,
self._message_parser.recursion_available,
RCode.NO_ERROR,
self._message_parser.message[12:],
questions_num=self._message_parser.questions_num,
answers_num=len(answers),
answers=answers)
self._dns_listener.sendto(answer, self._client_addr)
self._client_addr = None
finally:
sys.stderr.write('\nThe server was stopped. '
'All useful data will be serialize\n')
self._cache.serialize_cache()
def treat_data_from_receive(self, data):
try:
sender = socket.socket(AF_INET, SOCK_DGRAM)
sender.connect((self._next_dns_addr, self._port))
sender.settimeout(5)
sender.send(data)
data = sender.recv(1024)
sender.close()
except socket.error:
answer = MessageParser.to_bytes(
self._message_parser.transaction_id,
MessageType.QUERY,
self._message_parser.opcode,
HaveStatus.NO,
self._message_parser.recursion_required,
self._message_parser.recursion_available,
RCode.REFUSED,
self._message_parser.message[12:],
answers_num=0,
answers=[])
self._dns_listener.sendto(answer, self._client_addr)
return
self._dns_listener.sendto(data, self._client_addr)
answer_info = MessageParser()
answer_info.from_bytes(data)
for container in [
answer_info.answers, answer_info.resources_rights,
answer_info.additional_resources
]:
for resource in container:
self._cache.add_record(resource.ttl, resource.name.decode(),
resource.resource_type,
resource.resource_data,
resource.resource_class)
self._client_addr = None
