111 lines
4.2 KiB
Python
111 lines
4.2 KiB
Python
# Copyright (C) 2012 Nippon Telegraph and Telephone Corporation.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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# implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import struct
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from ryu.lib import addrconv
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from . import ether_types as ether
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from . import packet_base
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ARP_HW_TYPE_ETHERNET = 1 # ethernet hardware type
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# arp operation codes
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ARP_REQUEST = 1
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ARP_REPLY = 2
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ARP_REV_REQUEST = 3
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ARP_REV_REPLY = 4
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class arp(packet_base.PacketBase):
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"""ARP (RFC 826) header encoder/decoder class.
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An instance has the following attributes at least.
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Most of them are same to the on-wire counterparts but in host byte order.
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IPv4 addresses are represented as a string like '192.0.2.1'.
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MAC addresses are represented as a string like '08:60:6e:7f:74:e7'.
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__init__ takes the corresponding args in this order.
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============== ===================================== =====================
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Attribute Description Example
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============== ===================================== =====================
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hwtype Hardware address.
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proto Protocol address.
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hlen byte length of each hardware address.
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plen byte length of each protocol address.
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opcode operation codes.
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src_mac Hardware address of sender. '08:60:6e:7f:74:e7'
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src_ip Protocol address of sender. '192.0.2.1'
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dst_mac Hardware address of target. '00:00:00:00:00:00'
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dst_ip Protocol address of target. '192.0.2.2'
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============== ===================================== =====================
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"""
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_PACK_STR = '!HHBBH6s4s6s4s'
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_MIN_LEN = struct.calcsize(_PACK_STR)
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_TYPE = {
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'ascii': [
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'src_mac', 'src_ip', 'dst_mac', 'dst_ip'
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]
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}
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def __init__(self, hwtype=ARP_HW_TYPE_ETHERNET, proto=ether.ETH_TYPE_IP,
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hlen=6, plen=4, opcode=ARP_REQUEST,
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src_mac='ff:ff:ff:ff:ff:ff',
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src_ip='0.0.0.0',
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dst_mac='ff:ff:ff:ff:ff:ff',
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dst_ip='0.0.0.0'):
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super(arp, self).__init__()
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self.hwtype = hwtype
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self.proto = proto
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self.hlen = hlen
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self.plen = plen
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self.opcode = opcode
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self.src_mac = src_mac
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self.src_ip = src_ip
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self.dst_mac = dst_mac
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self.dst_ip = dst_ip
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@classmethod
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def parser(cls, buf):
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(hwtype, proto, hlen, plen, opcode, src_mac, src_ip,
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dst_mac, dst_ip) = struct.unpack_from(cls._PACK_STR, buf)
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return cls(hwtype, proto, hlen, plen, opcode,
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addrconv.mac.bin_to_text(src_mac),
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addrconv.ipv4.bin_to_text(src_ip),
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addrconv.mac.bin_to_text(dst_mac),
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addrconv.ipv4.bin_to_text(dst_ip)), None, buf[arp._MIN_LEN:]
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def serialize(self, payload, prev):
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return struct.pack(arp._PACK_STR, self.hwtype, self.proto,
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self.hlen, self.plen, self.opcode,
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addrconv.mac.text_to_bin(self.src_mac),
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addrconv.ipv4.text_to_bin(self.src_ip),
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addrconv.mac.text_to_bin(self.dst_mac),
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addrconv.ipv4.text_to_bin(self.dst_ip))
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def arp_ip(opcode, src_mac, src_ip, dst_mac, dst_ip):
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"""A convenient wrapper for IPv4 ARP for Ethernet.
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This is an equivalent of the following code.
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arp(ARP_HW_TYPE_ETHERNET, ether.ETH_TYPE_IP, \
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6, 4, opcode, src_mac, src_ip, dst_mac, dst_ip)
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"""
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return arp(ARP_HW_TYPE_ETHERNET, ether.ETH_TYPE_IP,
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6, # ether mac address length
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4, # ipv4 address length,
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opcode, src_mac, src_ip, dst_mac, dst_ip)
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