At Fri, 18 Nov 2016 20:07:38 +0000,
Olivier Desnoë wrote:
>
> This patch adds the ability to dissect and generate DHCPv6 packets. I
> needed it to develop a simple LDRA app (as defined in RFC 6221).
>
> Signed-off-by: Olivier DESNOE <[email protected]>
> ---
> diff --git a/ryu/lib/packet/dhcp6.py b/ryu/lib/packet/dhcp6.py
> new file mode 100644
> index 0000000..1102305
> --- /dev/null
> +++ b/ryu/lib/packet/dhcp6.py
> @@ -0,0 +1,301 @@
> +# 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
> +DHCP 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 binascii
> +import random
> +import struct
> +
> +from . import packet_base
> +from ryu.lib import addrconv
> +from ryu.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
> +
> + * For unrelayed messages only:
> + transaction_id The transaction ID for this message exchange.
> +
> + * For relayed messages only
> + hop_count Number of relay agents that have relayed this
> + message.
> + link_address 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 The address of the client or relay agent from which
> + the message to be relayed was received.
> +
> + * For unrelayed and relayed messages:
> + 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 = '\x00' + buf[1:] # unpack xid as a 4-byte integer
For python3 compatibility, it needs to be b'\x00'.
> + 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:])
> +
> + @classmethod
> + def parser(cls, buf):
> + try:
> + return cls._parser(buf)
> + except:
> + 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)
> + str = 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)
> + str = struct.pack(pack_str, self.transaction_id, seri_opt)
> + str = struct.pack('!B', self.msg_type) + str[1:]
> + return str
> +
> +
> +class options(stringify.StringifyMixin):
> + """DHCP (RFC 3315) options encoder/decoder class.
> +
> + This is used with ryu.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 = ""
> + 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 ryu.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) |
> + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> +
> + 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)
> diff --git a/ryu/lib/packet/udp.py b/ryu/lib/packet/udp.py
> index f39fb90..064263c 100644
> --- a/ryu/lib/packet/udp.py
> +++ b/ryu/lib/packet/udp.py
> @@ -18,6 +18,7 @@ import struct
> from . import packet_base
> from . import packet_utils
> from . import dhcp
> +from . import dhcp6
> from . import vxlan
>
>
> @@ -53,10 +54,12 @@ class udp(packet_base.PacketBase):
> @staticmethod
> def get_packet_type(src_port, dst_port):
> if ((src_port == 68 and dst_port == 67) or
> - (src_port == 67 and dst_port == 68) or
> - (src_port == 67 and
> - dst_port == 67)):
> + (src_port == 67 and dst_port == 68) or
> + (src_port == 67 and dst_port == 67)):
> return dhcp.dhcp
> + if (((src_port == 546 or src_port == 547) and dst_port == 547) or
This line can be written as follows, if you want.
if ((src_port in [546, 547] and dst_port == 547) or
> + (src_port == 547 and (dst_port == 546 or dst_port ==
> 547))):
> + return dhcp6.dhcp6
> if (dst_port == vxlan.UDP_DST_PORT or
> dst_port == vxlan.UDP_DST_PORT_OLD):
> return vxlan.vxlan
--
IWAMOTO Toshihiro
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