# $Id: arp.py 23 2006-11-08 15:45:33Z dugsong $
# -*- coding: utf-8 -*-
"""Address Resolution Protocol."""
from __future__ import absolute_import

from . import dpkt

# Hardware address format
ARP_HRD_ETH = 0x0001  # ethernet hardware
ARP_HRD_IEEE802 = 0x0006  # IEEE 802 hardware

# Protocol address format
ARP_PRO_IP = 0x0800  # IP protocol

# ARP operation
ARP_OP_REQUEST = 1  # request to resolve ha given pa
ARP_OP_REPLY = 2  # response giving hardware address
ARP_OP_REVREQUEST = 3  # request to resolve pa given ha
ARP_OP_REVREPLY = 4  # response giving protocol address


class ARP(dpkt.Packet):
    """Address Resolution Protocol.

    See more about the ARP on \
    https://en.wikipedia.org/wiki/Address_Resolution_Protocol

    Attributes:
        __hdr__: Header fields of ARP.
    """
    
    __hdr__ = (
        ('hrd', 'H', ARP_HRD_ETH),
        ('pro', 'H', ARP_PRO_IP),
        ('hln', 'B', 6),  # hardware address length
        ('pln', 'B', 4),  # protocol address length
        ('op', 'H', ARP_OP_REQUEST),
        ('sha', '6s', ''),
        ('spa', '4s', ''),
        ('tha', '6s', ''),
        ('tpa', '4s', '')
    )
