class ryu.lib.packet.arp.arp(hwtype=1, proto=2048, hlen=6, plen=4, opcode=1, src_mac='ff:ff:ff:ff:ff:ff', src_ip='', dst_mac='ff:ff:ff:ff:ff:ff', dst_ip='')

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 ''. 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. ''
dst_mac Hardware address of target. '00:00:00:00:00:00'
dst_ip Protocol address of target. ''
classmethod parser(buf)

Decode a protocol header.

This method is used only when decoding a packet.

Decode a protocol header at offset 0 in bytearray buf. Returns the following three objects.

  • An object to describe the decoded header.
  • A packet_base.PacketBase subclass appropriate for the rest of the packet. None when the rest of the packet should be considered as raw payload.
  • The rest of packet.
serialize(payload, prev)

Encode a protocol header.

This method is used only when encoding a packet.

Encode a protocol header. Returns a bytearray which contains the header.

payload is the rest of the packet which will immediately follow this header.

prev is a packet_base.PacketBase subclass for the outer protocol header. prev is None if the current header is the outer-most. For example, prev is ipv4 or ipv6 for tcp.serialize.

ryu.lib.packet.arp.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)