def parse(bytedata: bytes) -> tuple:
"""
:param bytedata data, from the dns packet stream
:return: tuple(AnswerItem, rest of bytedata)
:rtype AnswerItem, bytes
"""
name_field, bytedata = bread(bytedata, 2)
name_field = int.from_bytes(name_field, byteorder="big")
# 0bXY00000000000000 - X: 1 Y: 1 -> 11, X:0 Y:1 -> 1, X:1 Y:0 -> 10
name_type = 10 * ((name_field >> 15) & 0b1) + ((name_field >> 14) & 0b1)
name_offset = name_field & 0b001111111111111
assert name_type == 11
_type, bytedata = bread(bytedata, 2)
_type = int.from_bytes(_type, byteorder="big")
_class, bytedata = bread(bytedata, 2)
_class = int.from_bytes(_class, byteorder="big")
_ttl, bytedata = bread(bytedata, 4)
_ttl = int.from_bytes(_ttl, byteorder="big")
rdlen, bytedata = bread(bytedata, 2)
rdlen = int.from_bytes(rdlen, byteorder="big")
rddata, bytedata = bread(bytedata, rdlen)
rddata = QuestionTypes.unpack(_type, rddata)
return AnswerItem(QuestionItem(name_offset, _type, _class), _type, rddata, _ttl), bytedata
def parse(bytedata: bytes) -> tuple:
"""
:param bytedata data, from the dns packet stream
:return: tuple(QuestionItem, rest of bytedata)
:rtype QuestionItem, bytes
"""
domain = []
count = -1
while count != 0:
count, bytedata = bread(bytedata, 1)
count = int.from_bytes(count, byteorder="big")
if count != 0:
domain_part, bytedata = bread(bytedata, count)
domain.append(domain_part.decode())
qtype, bytedata = bread(bytedata, 2)
qtype = int.from_bytes(qtype, byteorder="big")
qclass, bytedata = bread(bytedata, 2)
qclass = int.from_bytes(qclass, byteorder="big")
return QuestionItem(domain, qtype, qclass), bytedata
def __init__(self, _msg=None):
"""
:type _msg byte
:param _msg Get byte array as input and form structured data
"""
if _msg is None:
self.message_id = generate_message_id()
self.header = Header()
self.question_section = []
self.answer_section = []
self.authority_section = []
self.additional_section = []
return
offset = 0
# parse data packet
self.message_id, _msg, offset = bread(_msg, 2, offset)
_pack1, _msg, offset = bread(_msg, 2, offset, data_fx=lambda x: int.from_bytes(x, byteorder="big"))
# declare sections
_size, _msg, offset = bread(_msg, 2, offset, data_fx=lambda x: int.from_bytes(x, byteorder="big"))
self.question_section = [None] * _size
# required to store question section offsets for answer_section "name"
question_offset_grid = [None] * _size
_size, _msg, offset = bread(_msg, 2, offset, data_fx=lambda x: int.from_bytes(x, byteorder="big"))
self.answer_section = [None] * _size
_size, _msg, offset = bread(_msg, 2, offset, data_fx=lambda x: int.from_bytes(x, byteorder="big"))
self.authority_section = [None] * _size
_size, _msg, offset = bread(_msg, 2, offset, data_fx=lambda x: int.from_bytes(x, byteorder="big"))
self.additional_section = [None] * _size
# decode header section
self.header = Header(_pack1)
# decode Question section
for i in range(0, len(self.question_section)):
la = len(_msg)
item, _msg = QuestionItem.parse(_msg)
lb = len(_msg)
question_offset_grid[i] = offset
self.question_section[i] = item
offset += la - lb
# decode Answer section
for i in range(0, len(self.answer_section)):
la = len(_msg)
item, _msg = AnswerItem.parse(_msg)
lb = len(_msg)
# here we will get answer name from the offset
loffset = item.name
for x in range(0, len(question_offset_grid)):
if question_offset_grid[x] <= loffset:
item.name = self.question_section[x].qname
self.answer_section[i] = item
offset += la - lb
# decode Authority section
for i in range(0, len(self.authority_section)):
la = len(_msg)
item, _msg = AnswerItem.parse(_msg)
lb = len(_msg)
# here we will get answer name from the offset
loffset = item.name
for x in range(0, len(question_offset_grid)):
if question_offset_grid[x] <= loffset:
item.name = self.question_section[x].qname
self.authority_section[i] = item
offset += la - lb
