DHCP6¶
DHCPv6 packet parser/serializer
[RFC 3315] DHCPv6 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) .... .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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class
os_ken.lib.packet.dhcp6.dhcp6(msg_type, options, transaction_id=None, hop_count=0, link_address='::', peer_address='::')¶ 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
transaction_id
For unrelayed messages only: the transaction ID for this message exchange.
hop_count
For relayed messages only: number of relay agents that have relayed this message.
link_address
For relayed messages only: 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
For relayed messages only: the address of the client or relay agent from which the message to be relayed was received.
options
Options carried in this message
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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.
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serialize(payload=None, prev=None)¶ 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.
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class
os_ken.lib.packet.dhcp6.option(code, data, length=0)¶ DHCP (RFC 3315) options encoder/decoder class.
This is used with os_ken.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) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Attribute
Description
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.
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class
os_ken.lib.packet.dhcp6.options(option_list=None, options_len=0)¶ DHCP (RFC 3315) options encoder/decoder class.
This is used with os_ken.lib.packet.dhcp6.dhcp6.
