class DNSPacketFactory:
request_factory = DNSRequestType
response_factory = DNSResponseType
def __init__(self, definitions):
self.codec = DNSCodec(definitions)
def serializeRequest(self, request, extended=False):
try:
encoded = self.codec.encodeRequest(request)
except OverflowError:
encoded = None
if encoded is not None and extended:
encoded = struct.pack('>H', len(encoded)) + encoded
return encoded
def normalizeRequest(self, request_s, extended=False):
if extended:
(length,) = struct.unpack('>H', (request_s + '\0\0')[:2])
request_s = request_s[2:]
if length != len(request_s):
request_s = ''
if request_s:
res = True, self.codec.decodeRequest(request_s)
else:
res = False, None
return res
def createRequestString(self, identifier, request_type, request_name, extended=False):
request = self.request_factory(identifier)
request.addQuestion(request_type, request_name)
try:
encoded = self.codec.encodeRequest(request)
except OverflowError:
encoded = None
if encoded is not None and extended:
encoded = struct.pack('>H', len(encoded)) + encoded
return encoded
def serializeResponse(self, response, extended=False):
encoded = self.codec.encodeResponse(response)
if extended:
encoded = struct.pack('>H', len(encoded)) + encoded
return encoded
def normalizeResponse(self, response_s, extended=False):
if extended:
(length,) = struct.unpack('>H', (response_s + '\0\0')[:2])
response_s = response_s[2:]
if length != len(response_s):
response_s = ''
if response_s:
res = True, self.codec.decodeResponse(response_s)
else:
res = False, None
return res
def __init__(self, definitions): self.codec = DNSCodec(definitions)
