150 lines
4.6 KiB
Python
150 lines
4.6 KiB
Python
# Copyright (C) 2012 Nippon Telegraph and Telephone Corporation.
|
|
#
|
|
# Licensed under the Apache License, Version 2.0 (the "License");
|
|
# you may not use this file except in compliance with the License.
|
|
# You may obtain a copy of the License at
|
|
#
|
|
# http://www.apache.org/licenses/LICENSE-2.0
|
|
#
|
|
# Unless required by applicable law or agreed to in writing, software
|
|
# distributed under the License is distributed on an "AS IS" BASIS,
|
|
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
|
|
# implied.
|
|
# See the License for the specific language governing permissions and
|
|
# limitations under the License.
|
|
|
|
import inspect
|
|
import struct
|
|
|
|
from . import packet_base
|
|
from . import ethernet
|
|
|
|
|
|
class Packet(object):
|
|
"""A packet decoder/encoder class.
|
|
|
|
An instance is used to either decode or encode a single packet.
|
|
|
|
*data* is a bytearray to describe a raw datagram to decode.
|
|
When decoding, a Packet object is iteratable.
|
|
Iterated values are protocol (ethernet, ipv4, ...) headers and the payload.
|
|
Protocol headers are instances of subclass of packet_base.PacketBase.
|
|
The payload is a bytearray. They are iterated in on-wire order.
|
|
|
|
*data* should be omitted when encoding a packet.
|
|
"""
|
|
|
|
def __init__(self, data=None, protocols=None, parse_cls=ethernet.ethernet):
|
|
super(Packet, self).__init__()
|
|
self.data = data
|
|
if protocols is None:
|
|
self.protocols = []
|
|
else:
|
|
self.protocols = protocols
|
|
if self.data:
|
|
self._parser(parse_cls)
|
|
|
|
def _parser(self, cls):
|
|
rest_data = self.data
|
|
while cls:
|
|
try:
|
|
proto, cls, rest_data = cls.parser(rest_data)
|
|
except struct.error:
|
|
break
|
|
if proto:
|
|
self.protocols.append(proto)
|
|
if rest_data:
|
|
self.protocols.append(rest_data)
|
|
|
|
def serialize(self):
|
|
"""Encode a packet and store the resulted bytearray in self.data.
|
|
|
|
This method is legal only when encoding a packet.
|
|
"""
|
|
|
|
self.data = bytearray()
|
|
r = self.protocols[::-1]
|
|
for i, p in enumerate(r):
|
|
if isinstance(p, packet_base.PacketBase):
|
|
if i == len(r) - 1:
|
|
prev = None
|
|
else:
|
|
prev = r[i + 1]
|
|
data = p.serialize(self.data, prev)
|
|
else:
|
|
data = str(p)
|
|
self.data = data + self.data
|
|
|
|
def add_protocol(self, proto):
|
|
"""Register a protocol *proto* for this packet.
|
|
|
|
This method is legal only when encoding a packet.
|
|
|
|
When encoding a packet, register a protocol (ethernet, ipv4, ...)
|
|
header to add to this packet.
|
|
Protocol headers should be registered in on-wire order before calling
|
|
self.serialize.
|
|
"""
|
|
|
|
self.protocols.append(proto)
|
|
|
|
def get_protocols(self, protocol):
|
|
"""Returns a list of protocols that matches to the specified protocol.
|
|
"""
|
|
if isinstance(protocol, packet_base.PacketBase):
|
|
protocol = protocol.__class__
|
|
assert issubclass(protocol, packet_base.PacketBase)
|
|
return [p for p in self.protocols if isinstance(p, protocol)]
|
|
|
|
def get_protocol(self, protocol):
|
|
"""Returns the firstly found protocol that matches to the
|
|
specified protocol.
|
|
"""
|
|
result = self.get_protocols(protocol)
|
|
if len(result) > 0:
|
|
return result[0]
|
|
return None
|
|
|
|
def __div__(self, trailer):
|
|
self.add_protocol(trailer)
|
|
return self
|
|
|
|
def __truediv__(self, trailer):
|
|
return self.__div__(trailer)
|
|
|
|
def __iter__(self):
|
|
return iter(self.protocols)
|
|
|
|
def __getitem__(self, idx):
|
|
return self.protocols[idx]
|
|
|
|
def __setitem__(self, idx, item):
|
|
self.protocols[idx] = item
|
|
|
|
def __delitem__(self, idx):
|
|
del self.protocols[idx]
|
|
|
|
def __len__(self):
|
|
return len(self.protocols)
|
|
|
|
def __contains__(self, protocol):
|
|
if (inspect.isclass(protocol) and
|
|
issubclass(protocol, packet_base.PacketBase)):
|
|
return protocol in [p.__class__ for p in self.protocols]
|
|
return protocol in self.protocols
|
|
|
|
def __str__(self):
|
|
return ', '.join(repr(protocol) for protocol in self.protocols)
|
|
__repr__ = __str__ # note: str(list) uses __repr__ for elements
|
|
|
|
|
|
# XXX: Hack for preventing recursive import
|
|
def _PacketBase__div__(self, trailer):
|
|
pkt = Packet()
|
|
pkt.add_protocol(self)
|
|
pkt.add_protocol(trailer)
|
|
return pkt
|
|
|
|
packet_base.PacketBase.__div__ = _PacketBase__div__
|
|
packet_base.PacketBase.__truediv__ = _PacketBase__div__
|