dhcpkit_vpp.protocols.layer4 module

Classes and constants for layer 4 protocols

class dhcpkit_vpp.protocols.layer4.UDP(source_port: int = 0, destination_port: int = 0, checksum: int = 0, payload: bytes = b'')[source]

Bases: dhcpkit_vpp.protocols.Layer4Protocol

The class for UDP packets.

calculate_checksum(l3_packet: dhcpkit_vpp.protocols.Layer3Packet)[source]

Calculate the checksum based on the current payload and the provided layer 3 packet.

Parameters:l3_packet – The layer 3 packet that contains this UDP message
Returns:The calculated checksum
classmethod determine_class(buffer: bytes, offset: int = 0) → type[source]

Return the appropriate class to parse this element with.

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 data
length

Return the length of this protocol+payload

Returns:The length
load_from(buffer: bytes, offset: int = 0, length: int = None) → int[source]

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
protocol_number = 17
save(zero_checksum: bool = False, recalculate_checksum_for: dhcpkit_vpp.protocols.Layer3Packet = None) → bytearray[source]

Save the internal state of this object as a buffer.

Parameters:
  • zero_checksum – Save with zeroes where the checksum should be
  • recalculate_checksum_for – Recalculate the checksum for the given layer 3 packet headers
Returns:

The buffer with the data from this element
validate()[source]

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

class dhcpkit_vpp.protocols.layer4.UnknownLayer4Protocol(data: bytes = b'')[source]

Bases: dhcpkit_vpp.protocols.Layer4Protocol, dhcpkit.protocol_element.UnknownProtocolElement

A layer 3 packet of unknown type

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

Return the appropriate class to parse this element with.

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 data
length

The length of our data

Returns:The length
save(zero_checksum: bool = False, recalculate_checksum_for: dhcpkit_vpp.protocols.Layer3Packet = None) → bytearray[source]

Save the internal state of this object as a buffer.

Parameters:
  • zero_checksum – Save with zeroes where the checksum should be
  • recalculate_checksum_for – Recalculate the checksum for the given layer 3 packet headers
Returns:

The buffer with the data from this element