3837a84eec
The patch teaches packet library to truncate padding octets. Change packet_base.parser() to return (header, next_type, rest_of_packet) The protocol class that knows its payload length should rest_of_packet where padding octets at the last of packet is truncated. As bonus, - fix ipv6 parser as ipv6 header doesn't have options. It seems copy-and-paste from ipv4 - improve ipv4, tcp a bit Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Cc: Shaun Crampton <Shaun.Crampton@metaswitch.com> Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp> Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
69 lines
2.4 KiB
Python
69 lines
2.4 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 struct
|
|
|
|
from . import packet_base
|
|
from . import packet_utils
|
|
|
|
|
|
class udp(packet_base.PacketBase):
|
|
"""UDP (RFC 768) header encoder/decoder class.
|
|
|
|
An instance has the following attributes at least.
|
|
Most of them are same to the on-wire counterparts but in host byte order.
|
|
__init__ takes the correspondig args in this order.
|
|
|
|
============== ====================
|
|
Attribute Description
|
|
============== ====================
|
|
src_port Source Port
|
|
dst_port Destination Port
|
|
total_length Length \
|
|
(0 means automatically-calculate when encoding)
|
|
csum Checksum \
|
|
(0 means automatically-calculate when encoding)
|
|
============== ====================
|
|
"""
|
|
|
|
_PACK_STR = '!HHHH'
|
|
_MIN_LEN = struct.calcsize(_PACK_STR)
|
|
|
|
def __init__(self, src_port, dst_port, total_length=0, csum=0):
|
|
super(udp, self).__init__()
|
|
self.src_port = src_port
|
|
self.dst_port = dst_port
|
|
self.total_length = total_length
|
|
self.csum = csum
|
|
|
|
@classmethod
|
|
def parser(cls, buf):
|
|
(src_port, dst_port, total_length, csum) = struct.unpack_from(
|
|
cls._PACK_STR, buf)
|
|
msg = cls(src_port, dst_port, total_length, csum)
|
|
return msg, None, buf[msg._MIN_LEN:total_length]
|
|
|
|
def serialize(self, payload, prev):
|
|
if self.total_length == 0:
|
|
self.total_length = udp._MIN_LEN + len(payload)
|
|
h = struct.pack(udp._PACK_STR, self.src_port, self.dst_port,
|
|
self.total_length, self.csum)
|
|
if self.csum == 0:
|
|
self.csum = packet_utils.checksum_ip(
|
|
prev, self.total_length, h + payload)
|
|
h = struct.pack(udp._PACK_STR, self.src_port, self.dst_port,
|
|
self.total_length, self.csum)
|
|
return h
|