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# Copyright (C) 2016 Bouygues Telecom.
#
# 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.
"""
DHCPv6 packet parser/serializer
[RFC 3315] DHCPv6 packet format:
The following diagram illustrates the format of DHCP messages sent
between clients and servers::
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg_type | transaction_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. options .
. (variable) .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
There are two relay agent messages, which share the following format::
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg_type | hop_count | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |
| link_address |
| |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |
| peer_address |
| |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. .
. options (variable number and length) .... .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
"""
import random
import struct
from . import packet_base
from os_ken.lib import addrconv
from os_ken.lib import stringify
# DHCPv6 message types
DHCPV6_SOLICIT = 1
DHCPV6_ADVERTISE = 2
DHCPV6_REQUEST = 3
DHCPV6_CONFIRM = 4
DHCPV6_RENEW = 5
DHCPV6_REBIND = 6
DHCPV6_REPLY = 7
DHCPV6_RELEASE = 8
DHCPV6_DECLINE = 9
DHCPV6_RECONFIGURE = 10
DHCPV6_INFORMATION_REQUEST = 11
DHCPV6_RELAY_FORW = 12
DHCPV6_RELAY_REPL = 13
# DHCPv6 option-codes
DHCPV6_OPTION_CLIENTID = 1
DHCPV6_OPTION_SERVERID = 2
DHCPV6_OPTION_IA_NA = 3
DHCPV6_OPTION_IA_TA = 4
DHCPV6_OPTION_IAADDR = 5
DHCPV6_OPTION_ORO = 6
DHCPV6_OPTION_PREFERENCE = 7
DHCPV6_OPTION_ELAPSED_TIME = 8
DHCPV6_OPTION_RELAY_MSG = 9
DHCPV6_OPTION_AUTH = 11
DHCPV6_OPTION_UNICAST = 12
DHCPV6_OPTION_STATUS_CODE = 13
DHCPV6_OPTION_RAPID_COMMIT = 14
DHCPV6_OPTION_USER_CLASS = 15
DHCPV6_OPTION_VENDOR_CLASS = 16
DHCPV6_OPTION_VENDOR_OPTS = 17
DHCPV6_OPTION_INTERFACE_ID = 18
DHCPV6_OPTION_RECONF_MSG = 19
DHCPV6_OPTION_RECONF_ACCEPT = 20
class dhcp6(packet_base.PacketBase):
"""DHCPv6 (RFC 3315) header encoder/decoder class.
The serialized packet would looks like the ones described
in the following sections.
* RFC 3315 DHCP packet format
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 corresponding args in this order.
============== ====================
Attribute Description
============== ====================
msg_type Identifies the DHCP message type
transaction_id For unrelayed messages only: the transaction ID for\
this message exchange.
hop_count For relayed messages only: number of relay agents that\
have relayed this message.
link_address For relayed messages only: a global or site-local address\
that will be used by the server to identify the link on\
which the client is located.
peer_address For relayed messages only: the address of the client or\
relay agent from which the message to be relayed was\
received.
options Options carried in this message
============== ====================
"""
_MIN_LEN = 8
_DHCPV6_UNPACK_STR = '!I'
_DHCPV6_RELAY_UNPACK_STR = '!H16s16s'
_DHCPV6_UNPACK_STR_LEN = struct.calcsize(_DHCPV6_UNPACK_STR)
_DHCPV6_RELAY_UNPACK_STR_LEN = struct.calcsize(_DHCPV6_RELAY_UNPACK_STR)
_DHCPV6_PACK_STR = '!I'
_DHCPV6_RELAY_PACK_STR = '!H16s16s'
def __init__(self, msg_type, options, transaction_id=None, hop_count=0,
link_address='::', peer_address='::'):
super(dhcp6, self).__init__()
self.msg_type = msg_type
self.options = options
if transaction_id is None:
self.transaction_id = random.randint(0, 0xffffff)
else:
self.transaction_id = transaction_id
self.hop_count = hop_count
self.link_address = link_address
self.peer_address = peer_address
@classmethod
def parser(cls, buf):
(msg_type, ) = struct.unpack_from('!B', buf)
buf = b'\x00' + buf[1:] # unpack xid as a 4-byte integer
if msg_type == DHCPV6_RELAY_FORW or msg_type == DHCPV6_RELAY_REPL:
(hop_count, link_address, peer_address) \
= struct.unpack_from(cls._DHCPV6_RELAY_UNPACK_STR, buf)
length = struct.calcsize(cls._DHCPV6_RELAY_UNPACK_STR)
else:
(transaction_id, ) \
= struct.unpack_from(cls._DHCPV6_UNPACK_STR, buf)
length = struct.calcsize(cls._DHCPV6_UNPACK_STR)
if len(buf) > length:
parse_opt = options.parser(buf[length:])
length += parse_opt.options_len
if msg_type == DHCPV6_RELAY_FORW or msg_type == DHCPV6_RELAY_REPL:
return (cls(msg_type, parse_opt, 0, hop_count,
addrconv.ipv6.bin_to_text(link_address),
addrconv.ipv6.bin_to_text(peer_address)),
None, buf[length:])
else:
return (cls(msg_type, parse_opt, transaction_id),
None, buf[length:])
else:
return None, None, buf
def serialize(self, payload=None, prev=None):
seri_opt = self.options.serialize()
if (self.msg_type == DHCPV6_RELAY_FORW or
self.msg_type == DHCPV6_RELAY_REPL):
pack_str = '%s%ds' % (self._DHCPV6_RELAY_PACK_STR,
self.options.options_len)
buf = struct.pack(pack_str, self.hop_count,
addrconv.ipv6.text_to_bin(self.link_address),
addrconv.ipv6.text_to_bin(self.peer_address),
seri_opt)
else:
pack_str = '%s%ds' % (self._DHCPV6_PACK_STR,
self.options.options_len)
buf = struct.pack(pack_str, self.transaction_id, seri_opt)
return struct.pack('!B', self.msg_type) + buf[1:]
class options(stringify.StringifyMixin):
"""DHCP (RFC 3315) options encoder/decoder class.
This is used with os_ken.lib.packet.dhcp6.dhcp6.
"""
def __init__(self, option_list=None, options_len=0):
super(options, self).__init__()
if option_list is None:
self.option_list = []
else:
self.option_list = option_list
self.options_len = options_len
@classmethod
def parser(cls, buf):
opt_parse_list = []
offset = 0
while len(buf) > offset:
opt_buf = buf[offset:]
opt = option.parser(opt_buf)
opt_parse_list.append(opt)
offset += opt.length + 4
return cls(opt_parse_list, len(buf))
def serialize(self):
seri_opt = bytes()
for opt in self.option_list:
seri_opt += opt.serialize()
if self.options_len == 0:
self.options_len = len(seri_opt)
return seri_opt
class option(stringify.StringifyMixin):
"""DHCP (RFC 3315) options encoder/decoder class.
This is used with os_ken.lib.packet.dhcp6.dhcp6.options.
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 corresponding args in this order.
The format of DHCP options is::
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-code | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-data |
| (option-len octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
============== ====================
Attribute Description
============== ====================
option-code An unsigned integer identifying the specific option\
type carried in this option.
option-len An unsigned integer giving the length of the\
option-data field in this option in octets.
option-data The data for the option; the format of this data\
depends on the definition of the option.
============== ====================
"""
_UNPACK_STR = '!H'
_UNPACK_STR_LEN = struct.calcsize(_UNPACK_STR)
_PACK_STR = '!HH%ds'
def __init__(self, code, data, length=0):
super(option, self).__init__()
self.code = code
self.data = data
self.length = length
@classmethod
def parser(cls, buf):
code = struct.unpack_from(cls._UNPACK_STR, buf)[0]
buf = buf[cls._UNPACK_STR_LEN:]
length = struct.unpack_from(cls._UNPACK_STR, buf)[0]
buf = buf[cls._UNPACK_STR_LEN:]
value_unpack_str = '%ds' % length
data = struct.unpack_from(value_unpack_str, buf)[0]
return cls(code, data, length)
def serialize(self):
if self.length == 0:
self.length = len(self.data)
options_pack_str = self._PACK_STR % self.length
return struct.pack(options_pack_str, self.code, self.length, self.data)
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