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# 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 os_ken.lib import addrconv
from . import ether_types as ether
from . import packet_base
ARP_HW_TYPE_ETHERNET = 1 # ethernet hardware type
# arp operation codes
ARP_REQUEST = 1
ARP_REPLY = 2
ARP_REV_REQUEST = 3
ARP_REV_REPLY = 4
class arp(packet_base.PacketBase):
"""ARP (RFC 826) 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.
IPv4 addresses are represented as a string like '192.0.2.1'.
MAC addresses are represented as a string like '08:60:6e:7f:74:e7'.
__init__ takes the corresponding args in this order.
============== ===================================== =====================
Attribute Description Example
============== ===================================== =====================
hwtype Hardware address.
proto Protocol address.
hlen byte length of each hardware address.
plen byte length of each protocol address.
opcode operation codes.
src_mac Hardware address of sender. '08:60:6e:7f:74:e7'
src_ip Protocol address of sender. '192.0.2.1'
dst_mac Hardware address of target. '00:00:00:00:00:00'
dst_ip Protocol address of target. '192.0.2.2'
============== ===================================== =====================
"""
_PACK_STR = '!HHBBH6s4s6s4s'
_MIN_LEN = struct.calcsize(_PACK_STR)
_TYPE = {
'ascii': [
'src_mac', 'src_ip', 'dst_mac', 'dst_ip'
]
}
def __init__(self, hwtype=ARP_HW_TYPE_ETHERNET, proto=ether.ETH_TYPE_IP,
hlen=6, plen=4, opcode=ARP_REQUEST,
src_mac='ff:ff:ff:ff:ff:ff',
src_ip='0.0.0.0',
dst_mac='ff:ff:ff:ff:ff:ff',
dst_ip='0.0.0.0'):
super(arp, self).__init__()
self.hwtype = hwtype
self.proto = proto
self.hlen = hlen
self.plen = plen
self.opcode = opcode
self.src_mac = src_mac
self.src_ip = src_ip
self.dst_mac = dst_mac
self.dst_ip = dst_ip
@classmethod
def parser(cls, buf):
(hwtype, proto, hlen, plen, opcode, src_mac, src_ip,
dst_mac, dst_ip) = struct.unpack_from(cls._PACK_STR, buf)
return cls(hwtype, proto, hlen, plen, opcode,
addrconv.mac.bin_to_text(src_mac),
addrconv.ipv4.bin_to_text(src_ip),
addrconv.mac.bin_to_text(dst_mac),
addrconv.ipv4.bin_to_text(dst_ip)), None, buf[arp._MIN_LEN:]
def serialize(self, payload, prev):
return struct.pack(arp._PACK_STR, self.hwtype, self.proto,
self.hlen, self.plen, self.opcode,
addrconv.mac.text_to_bin(self.src_mac),
addrconv.ipv4.text_to_bin(self.src_ip),
addrconv.mac.text_to_bin(self.dst_mac),
addrconv.ipv4.text_to_bin(self.dst_ip))
def arp_ip(opcode, src_mac, src_ip, dst_mac, dst_ip):
"""A convenient wrapper for IPv4 ARP for Ethernet.
This is an equivalent of the following code.
arp(ARP_HW_TYPE_ETHERNET, ether.ETH_TYPE_IP, \
6, 4, opcode, src_mac, src_ip, dst_mac, dst_ip)
"""
return arp(ARP_HW_TYPE_ETHERNET, ether.ETH_TYPE_IP,
6, # ether mac address length
4, # ipv4 address length,
opcode, src_mac, src_ip, dst_mac, dst_ip)
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