class Ethernet(Model):
dst_mac = BytesField(48)
src_mac = BytesField(48)
type = IntField(16)
def payload_type(self):
if self.type == 0x0800:
# TODO: add more protocols
return IP
else:
return None
class TCP(Model):
src_port = IntField(16)
dst_port = IntField(16)
seq_number = IntField(32)
ack_number = IntField(32)
data_offset = IntField(4, default=5)
reserved = BitsField(3)
ns = IntField(1)
cwr = IntField(1)
ece = IntField(1)
urg = IntField(1)
ack = IntField(1)
psh = IntField(1)
rst = IntField(1)
syn = IntField(1)
fin = IntField(1)
window_size = IntField(16)
checksum = IntField(16)
urgent_pointer = IntField(16)
class OptionMaxSegmentSize(Model):
prefix = IntField(8, default=2)
length = IntField(8, default=4)
value = IntField(16)
class OptionWindowScale(Model):
prefix = IntField(8, default=3)
length = IntField(8, default=3)
value = IntField(8)
class OptionSelectiveAckPermitted(Model):
prefix = IntField(8, default=4)
length = IntField(8, default=2)
class OptionSACK(Model):
prefix = IntField(8, default=5)
length = IntField(8)
value = BitsField(length=lambda self: 8 * (self.length - 2))
class OptionTimestamp(Model):
prefix = IntField(8, default=8)
length = IntField(8, default=10)
value = IntField(64)
options = PrefixedOptionsField(
length=lambda self: max(0, 32 * (self.data_offset - 5)),
options={
b'\x00': b'\x00',
b'\x01': b'\x01',
b'\x02': OptionMaxSegmentSize,
b'\x03': OptionWindowScale,
b'\x04': OptionSelectiveAckPermitted,
b'\x05': OptionSACK,
b'\x08': OptionTimestamp,
})
def fill_checksum(self):
self.checksum = 0
ip = self.parent
placebo_head = ip.src_ip.to_bytes(4, "big") + \
ip.dst_ip.to_bytes(4, "big") + \
b'\x00\x06' + \
len(bytes(self)).to_bytes(2, "big")
self.checksum = one_complement_checksum(placebo_head + bytes(self))
class OptionTimestamp(Model):
prefix = IntField(8, default=8)
length = IntField(8, default=10)
value = IntField(64)
class OptionSACK(Model):
prefix = IntField(8, default=5)
length = IntField(8)
value = BitsField(length=lambda self: 8 * (self.length - 2))
class OptionSelectiveAckPermitted(Model):
prefix = IntField(8, default=4)
length = IntField(8, default=2)
class OptionWindowScale(Model):
prefix = IntField(8, default=3)
length = IntField(8, default=3)
value = IntField(8)
class OptionMaxSegmentSize(Model):
prefix = IntField(8, default=2)
length = IntField(8, default=4)
value = IntField(16)
class IP(Model):
version = IntField(4, default=4)
ihl = IntField(4, default=5)
dscp = IntField(6)
ecn = IntField(2)
total_length = IntField(16)
identification = IntField(16)
flags = BitsField(3)
fragment_offset = IntField(13)
ttl = IntField(8)
protocol = IntField(8)
checksum = IntField(16)
src_ip = IntField(32)
dst_ip = IntField(32)
options = BitsField(lambda self: max(0, (self.ihl - 5) * 32))
def fill_checksum(self):
self.checksum = 0
self.checksum = one_complement_checksum(bytes(self.solid_data))
def payload_type(self):
if self.protocol == 0x06:
return TCP
else:
# TODO: add more
return None