def decode_name(self, last=-1):
"""
Orig docstring: Decode label at current offset in buffer (following pointers
to cached elements where necessary)
This method has overwritten because of Kitty. Sometimes it produces fuzzed data
with iso-8859-1 encodings that the original DNS lib can not handle because that type
of DNS domain label not exists in real world scenario but here it is.
"""
label = []
done = False
while not done:
(length,) = self.unpack("!B")
if get_bits(length, 6, 2) == 3:
# Pointer
self.offset -= 1
pointer = get_bits(self.unpack("!H")[0], 0, 14)
save = self.offset
if last == save:
raise BufferError(
f"Recursive pointer in DNSLabel [offset={self.offset:d},pointer={pointer:d},"
f"length={len(self.data):d}]")
if pointer < self.offset:
self.offset = pointer
else:
# Pointer can't point forwards
raise BufferError(
f"Invalid pointer in DNSLabel [offset={self.offset:d},pointer={pointer:d},"
f"length={len(self.data):d}]")
label.extend(self.decode_name(save).label)
self.offset = save
done = True
else:
if length > 0:
l = self.get(length)
try:
l.decode()
except:
l.decode('iso-8859-1')
label.append(l)
else:
done = True
return DNSLabel(label)
def decode_name(self, last=-1):
"""
Decode label at current offset in buffer (following pointers
to cached elements where necessary)
"""
label = []
done = False
while not done:
(length, ) = self.unpack("!B")
if get_bits(length, 6, 2) == 3:
# Pointer
self.offset -= 1
pointer = get_bits(self.unpack("!H")[0], 0, 14)
save = self.offset
if last == save:
raise BufferError(
"Recursive pointer in DNSLabel [offset=%d,pointer=%d,length=%d]"
% (self.offset, pointer, len(self.data)))
if pointer < self.offset:
self.offset = pointer
else:
# Pointer can't point forwards
raise BufferError(
"Invalid pointer in DNSLabel [offset=%d,pointer=%d,length=%d]"
% (self.offset, pointer, len(self.data)))
label.extend(self.decode_name(save).label)
self.offset = save
done = True
else:
if length > 0:
l = self.get(length)
try:
l.decode()
except UnicodeDecodeError:
raise BufferError("Invalid label <%s>" % l)
label.append(l)
else:
done = True
return DNSLabel(label)