dhcpkit.ipv6.messages module

Classes and constants for the message types defined in RFC 3315

class dhcpkit.ipv6.messages.AdvertiseMessage(transaction_id: bytes = b'x00x00x00', options: Iterable = None)

Bases: dhcpkit.ipv6.messages.ClientServerMessage

A server sends an Advertise message to indicate that it is available for DHCP service, in response to a Solicit message received from a client.

from_server_to_client = True

message_type = 2

class dhcpkit.ipv6.messages.ClientServerMessage(transaction_id: bytes = b'x00x00x00', options: Iterable = None)

Bases: dhcpkit.ipv6.messages.Message

RFC 3315#section-6

All DHCP messages sent between clients and servers share an identical fixed format header and a variable format area for options.

All values in the message header and in options are in network byte order.

Options are stored serially in the options field, with no padding between the options. Options are byte-aligned but are not aligned in any other way such as on 2 or 4 byte boundaries.

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)                          .
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

msg-type

Identifies the DHCP message type; the available message types are listed in section 5.3.

transaction-id

The transaction ID for this message exchange.

options

Options carried in this message; options are described in section 22.

get_option_of_type(*args) → Union

Get the first option that is a subclass of the given class.

Parameters:args – The classes to look for Returns:The option or None

get_options_of_type(*args) → List

Get all options that are subclasses of the given class.

Parameters:args – The classes to look for Returns:The list of options

load_from(buffer: bytes, offset: int = 0, length: int = None) → int

Load the internal state of this object from the given buffer. The buffer may contain more data after the structured element is parsed. This data is ignored.

Parameters:

• buffer – The buffer to read data from
• offset – The offset in the buffer where to start reading
• length – The amount of data we are allowed to read from the buffer

Returns:

The number of bytes used from the buffer

save() → Union

Save the internal state of this object as a buffer.

Returns:The buffer with the data from this element

validate()

Validate that the contents of this object conform to protocol specs.

class dhcpkit.ipv6.messages.ConfirmMessage(transaction_id: bytes = b'x00x00x00', options: Iterable = None)

Bases: dhcpkit.ipv6.messages.ClientServerMessage

A client sends a Confirm message to any available server to determine whether the addresses it was assigned are still appropriate to the link to which the client is connected.

from_client_to_server = True

message_type = 4

class dhcpkit.ipv6.messages.DeclineMessage(transaction_id: bytes = b'x00x00x00', options: Iterable = None)

Bases: dhcpkit.ipv6.messages.ClientServerMessage

A client sends a Decline message to a server to indicate that the client has determined that one or more addresses assigned by the server are already in use on the link to which the client is connected.

from_client_to_server = True

message_type = 9

class dhcpkit.ipv6.messages.InformationRequestMessage(transaction_id: bytes = b'x00x00x00', options: Iterable = None)

Bases: dhcpkit.ipv6.messages.ClientServerMessage

A client sends an Information-request message to a server to request configuration parameters without the assignment of any IP addresses to the client.

from_client_to_server = True

message_type = 11

class dhcpkit.ipv6.messages.Message

Bases: dhcpkit.protocol_element.ProtocolElement

The base class for DHCP messages.

classmethod determine_class(buffer: bytes, offset: int = 0) → type

Return the appropriate subclass from the registry, or UnknownClientServerMessage if no subclass is registered.

Parameters:

• buffer – The buffer to read data from
• offset – The offset in the buffer where to start reading

Returns:

The best known class for this message data

from_client_to_server = False

from_server_to_client = False

message_type = 0

class dhcpkit.ipv6.messages.RebindMessage(transaction_id: bytes = b'x00x00x00', options: Iterable = None)

Bases: dhcpkit.ipv6.messages.ClientServerMessage

A client sends a Rebind message to any available server to extend the lifetimes on the addresses assigned to the client and to update other configuration parameters; this message is sent after a client receives no response to a Renew message.

from_client_to_server = True

message_type = 6

class dhcpkit.ipv6.messages.ReconfigureMessage(transaction_id: bytes = b'x00x00x00', options: Iterable = None)

Bases: dhcpkit.ipv6.messages.ClientServerMessage

A server sends a Reconfigure message to a client to inform the client that the server has new or updated configuration parameters, and that the client is to initiate a Renew/Reply or Information-request/Reply transaction with the server in order to receive the updated information.

from_server_to_client = True

message_type = 10

class dhcpkit.ipv6.messages.RelayForwardMessage(hop_count: int = 0, link_address: ipaddress.IPv6Address = None, peer_address: ipaddress.IPv6Address = None, options: Iterable = None)

Bases: dhcpkit.ipv6.messages.RelayServerMessage

A relay agent sends a Relay-forward message to relay messages to servers, either directly or through another relay agent. The received message, either a client message or a Relay-forward message from another relay agent, is encapsulated in an option in the Relay-forward message.

from_client_to_server = True

message_type = 12

wrap_response(response: dhcpkit.ipv6.messages.ClientServerMessage) → dhcpkit.ipv6.messages.RelayReplyMessage

The incoming message was wrapped in this RelayForwardMessage. Let this RelayForwardMessage then create a RelayReplyMessage with the correct options and wrap the reply .

Parameters:response – The response that is going to be sent to the client Returns:The RelayReplyMessage wrapping the response Return type:RelayReplyMessage

class dhcpkit.ipv6.messages.RelayReplyMessage(hop_count: int = 0, link_address: ipaddress.IPv6Address = None, peer_address: ipaddress.IPv6Address = None, options: Iterable = None)

Bases: dhcpkit.ipv6.messages.RelayServerMessage

A server sends a Relay-reply message to a relay agent containing a message that the relay agent delivers to a client. The Relay-reply message may be relayed by other relay agents for delivery to the destination relay agent.

The server encapsulates the client message as an option in the Relay-reply message, which the relay agent extracts and relays to the client.

from_server_to_client = True

message_type = 13

class dhcpkit.ipv6.messages.RelayServerMessage(hop_count: int = 0, link_address: ipaddress.IPv6Address = None, peer_address: ipaddress.IPv6Address = None, options: Iterable = None)

Bases: dhcpkit.ipv6.messages.Message

RFC 3315#section-7

Relay agents exchange messages with servers to relay messages between clients and servers that are not connected to the same link.

All values in the message header and in options are in network byte order.

Options are stored serially in the options field, with no padding between the options. Options are byte-aligned but are not aligned in any other way such as on 2 or 4 byte boundaries.

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)   ....        .
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

get_option_of_type(*args) → Union

Get the first option that is a subclass of the given class.

Parameters:args – The classes to look for Returns:The option or None

get_options_of_type(*args) → List

Get all options that are subclasses of the given class.

Parameters:args – The classes to look for Returns:The list of options

inner_message

Utility method to easily get the innermost message from the RelayMessageOption inside this RelayServerMessage.

Returns:The message, if found

inner_relay_message

Utility method to easily get the innermost relay message from the RelayMessageOption inside this RelayServerMessage.

Returns:The message, if found Return type:RelayServerMessage or None

load_from(buffer: bytes, offset: int = 0, length: int = None) → int

Load the internal state of this object from the given buffer. The buffer may contain more data after the structured element is parsed. This data is ignored.

Parameters:

• buffer – The buffer to read data from
• offset – The offset in the buffer where to start reading
• length – The amount of data we are allowed to read from the buffer

Returns:

The number of bytes used from the buffer

relayed_message

Utility method to easily get the relayed message from the RelayMessageOption inside this RelayServerMessage.

Returns:The message, if found

save() → Union

Save the internal state of this object as a buffer.

Returns:The buffer with the data from this element

validate()

Validate that the contents of this object conform to protocol specs.

class dhcpkit.ipv6.messages.ReleaseMessage(transaction_id: bytes = b'x00x00x00', options: Iterable = None)

Bases: dhcpkit.ipv6.messages.ClientServerMessage

A client sends a Release message to the server that assigned addresses to the client to indicate that the client will no longer use one or more of the assigned addresses.

from_client_to_server = True

message_type = 8

class dhcpkit.ipv6.messages.RenewMessage(transaction_id: bytes = b'x00x00x00', options: Iterable = None)

Bases: dhcpkit.ipv6.messages.ClientServerMessage

A client sends a Renew message to the server that originally provided the client’s addresses and configuration parameters to extend the lifetimes on the addresses assigned to the client and to update other configuration parameters.

from_client_to_server = True

message_type = 5

class dhcpkit.ipv6.messages.ReplyMessage(transaction_id: bytes = b'x00x00x00', options: Iterable = None)

Bases: dhcpkit.ipv6.messages.ClientServerMessage

A server sends a Reply message containing assigned addresses and configuration parameters in response to a Solicit, Request, Renew, Rebind message received from a client. A server sends a Reply message containing configuration parameters in response to an Information-request message. A server sends a Reply message in response to a Confirm message confirming or denying that the addresses assigned to the client are appropriate to the link to which the client is connected. A server sends a Reply message to acknowledge receipt of a Release or Decline message.

from_server_to_client = True

message_type = 7

class dhcpkit.ipv6.messages.RequestMessage(transaction_id: bytes = b'x00x00x00', options: Iterable = None)

Bases: dhcpkit.ipv6.messages.ClientServerMessage

A client sends a Request message to request configuration parameters, including IP addresses, from a specific server.

from_client_to_server = True

message_type = 3

class dhcpkit.ipv6.messages.SolicitMessage(transaction_id: bytes = b'x00x00x00', options: Iterable = None)

Bases: dhcpkit.ipv6.messages.ClientServerMessage

SOLICIT (1)

A client sends a Solicit message to locate servers.

from_client_to_server = True

message_type = 1

class dhcpkit.ipv6.messages.UnknownMessage(message_type: int = 0, message_data: bytes = b'')

Bases: dhcpkit.ipv6.messages.Message

Container for raw message content for cases where we don’t know how to decode the message.

load_from(buffer: bytes, offset: int = 0, length: int = None) → int

Load the internal state of this object from the given buffer. The buffer may contain more data after the structured element is parsed. This data is ignored.

Parameters:

• buffer – The buffer to read data from
• offset – The offset in the buffer where to start reading
• length – The amount of data we are allowed to read from the buffer

Returns:

The number of bytes used from the buffer

save() → Union

Save the internal state of this object as a buffer.

Returns:The buffer with the data from this element

validate()

Validate that the contents of this object conform to protocol specs.