OSPF - Open Shortest Path First

pcapkit.protocols.application.ospf contains OSPF only, which implements extractor for Open Shortest Path First (OSPF) [*], whose structure is described as below:

Octets	Bits	Name	Description
0	0	ospf.version	Version Number
1	8	ospf.type	Type
2	16	ospf.len	Packet Length (header included)
4	32	ospf.router_id	Router ID
8	64	ospf.area_id	Area ID
12	96	ospf.chksum	Checksum
14	112	ospf.autype	Authentication Type
16	128	ospf.auth	Authentication

class pcapkit.protocols.application.ospf.OSPF(file=None, length=None, **kwargs)

Bases: Application[OSPF, OSPF]

This class implements Open Shortest Path First.

A routing protocol computes the forwarding table rather than forwarding packets, so it is a user of the stack rather than part of its forwarding path. RFC 1812 Section 7 places it accordingly, titling that chapter “APPLICATION LAYER - ROUTING PROTOCOLS” with OSPF at §7.2.2, while RFC 1812 Section 4.1 confines the internet layer to IP, ICMP and IGMP. Hence Application as the base, and layer == 'Application'. See Protocol Layer Placement.

Note

The subpackage does not track the dispatch tier. OSPF is dispatched from Internet.__proto__ at OSPFIGP (IANA protocol number 89), since IP is what carries it.

property name: str

Name of current protocol.

property alias: str

Acronym of current protocol.

property length: Literal[24]

Header length of current protocol.

property type: Packet

OSPF packet type.

read(length=None, **kwargs)

Read Open Shortest Path First.

Structure of OSPF header [RFC 2328]:

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   Version #   |     Type      |         Packet length         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                          Router ID                            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                           Area ID                             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|           Checksum            |             AuType            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       Authentication                          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       Authentication                          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Parameters:

• length (int | None) – Length of packet data.

• **kwargs (Any) – Arbitrary keyword arguments.

Return type:

OSPF

Returns:

Parsed packet data.

make(version=2, type=<Packet.Hello: 1>, type_default=None, type_namespace=None, type_reversed=False, router_id='0.0.0.0', area_id='0.0.0.0', checksum=b'\\x00\\x00', auth_type=<Authentication.No_Authentication: 0>, auth_type_default=None, auth_type_namespace=None, auth_type_reversed=False, auth_data=b'\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x00', payload=b'', **kwargs)

Make (construct) packet data.

Parameters:

• version (int) – OSPF version number.

• type (Packet | IntEnum | IntEnum | str | int) – OSPF packet type.

• type_default (int | None) – Default value for type if not specified.

• type_namespace (dict[str, int] | dict[int, str] | Type[IntEnum] | Type[IntEnum] | None) – Namespace for type.

• type_reversed (bool) – Reverse namespace for type.

• router_id (IPv4Address | str | bytes | bytearray) – Router ID.

• area_id (IPv4Address | str | bytes | bytearray) – Area ID.

• checksum (bytes) – Checksum.

• auth_type (Authentication | IntEnum | IntEnum | str | int) – Authentication type.

• auth_type_default (int | None) – Default value for auth_type if not specified.

• auth_type_namespace (dict[str, int] | dict[int, str] | Type[IntEnum] | Type[IntEnum] | None) – Namespace for auth_type.

• auth_type_reversed (bool) – Reverse namespace for auth_type.

• auth_data (bytes | CrytographicAuthentication | CrytographicAuthentication) – Authentication data.

• payload (bytes | ProtocolBase | Schema) – Payload data.

• **kwargs (Any) – Arbitrary keyword arguments.

Return type:

OSPF

Returns:

Constructed packet data.

classmethod _make_data(data)

Create key-value pairs from data for protocol construction.

Parameters:

data (OSPF) – protocol data

Return type:

dict[str, Any]

Returns:

Key-value pairs for protocol construction.

_read_encrypt_auth(schema)

Read Authentication field when Cryptographic Authentication is employed, i.e. autype is 2.

Structure of Cryptographic Authentication [RFC 2328]:

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|              0                |    Key ID     | Auth Data Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                 Cryptographic sequence number                 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Parameters:

schema (CrytographicAuthentication) – parsed authentication data

Return type:

CrytographicAuthentication

Returns:

Parsed packet data.

_make_encrypt_auth(auth_data)

Make Authentication field when Cryptographic Authentication is employed.

Parameters:

auth_data (bytes | CrytographicAuthentication | CrytographicAuthentication) – Authentication data.

Return type:

bytes | CrytographicAuthentication

Returns:

Authentication bytes.

classmethod __index__()

Numeral registry index of the protocol.

Return type:

TransType

Returns:

Numeral registry index of the protocol in IANA.

Header Schemas

class pcapkit.protocols.schema.application.ospf.OSPF(*args: _VT, **kwargs: _VT)

Bases: Schema

Header schema for OSPF packet.

version: int = <UInt8Field version>

Version.

type: Packet = <EnumField type>

Type.

length: int = <UInt16Field length>

Length.

router_id: IPv4Address = <IPv4AddressField router_id>

Router ID.

area_id: IPv4Address = <IPv4AddressField area_id>

Area ID.

checksum: bytes = <BytesField checksum>

Checksum.

auth_type: Authentication = <EnumField auth_type>

Authentication type.

auth_data: bytes | CrytographicAuthentication = <SwitchField auth_data>

Authentication data.

payload: bytes = <PayloadField payload>

Payload.

class pcapkit.protocols.schema.application.ospf.CrytographicAuthentication(*args: _VT, **kwargs: _VT)

Bases: Schema

Header schema for OSPF cryptographic authentication.

reserved: bytes = <PaddingField reserved>

Reserved bytes.

key_id: int = <UInt8Field key_id>

Key ID.

len: int = <UInt8Field len>

Length.

seq: int = <UInt32Field seq>

Sequence number.

Auxiliary Functions

pcapkit.protocols.schema.application.ospf.ospf_auth_data_selector(pkt)

Selector function for OSPF.auth_data field.

Parameters:

pkt (dict[str, Any]) – Packet data.

Return type:

FieldBase

Returns:

• If OSPF.auth_type is 2, a SchemaField wrapped CrytographicAuthentication instance.

• Otherwise, a BytesField instance.

Data Models

class pcapkit.protocols.data.application.ospf.OSPF(*args: VT, **kwargs: VT)

Bases: Protocol

Data model for OSPF packet.

version: int

Version number.

type: Packet

Type.

len: int

Packet length (header included).

router_id: IPv4Address

Router ID.

area_id: IPv4Address

Area ID.

chksum: bytes

Checksum.

autype: Authentication

Authentication type.

auth: bytes | CrytographicAuthentication

Authentication.

class pcapkit.protocols.data.application.ospf.CrytographicAuthentication(*args: VT, **kwargs: VT)

Bases: Data

Data model for OSPF crytographic authentication.

key_id: int

Key ID.

len: int

Authentication data length.

seq: int

Cryptographic sequence number.

Footnotes

[*]

https://en.wikipedia.org/wiki/Open_Shortest_Path_First