OSPF - Open Shortest Path First¶

pcapkit.protocols.application.ospf contains OSPF only, which implements an 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

Added in version 1.5.0: Moved here from pcapkit.protocols.link.ospf, with its data model and header schema. OSPF derives from Application, so its layer is 'Application' (#719).

Removed in version 1.5.0: pcapkit.protocols.link.ospf, pcapkit.protocols.data.link.ospf and pcapkit.protocols.schema.link.ospf, the OSPF name that pcapkit.protocols.link, pcapkit.protocols.data.link and pcapkit.protocols.schema.link each exported, and the OSPF_CrytographicAuthentication name that pcapkit.protocols.data.link and pcapkit.protocols.schema.link exported, with no alias (#719, #1090).

Changed in version 1.5.0: A rebuild keeps the parsed Packet Length and the octets past it, where make() recomputed the length from the payload and dropped those octets; it takes them as packet_length and trailer (#1249, #1455).

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

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)[source]¶

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, type_default=None, type_namespace=None, type_reversed=False, packet_length=None, router_id='0.0.0.0', area_id='0.0.0.0', checksum=b'\x00\x00', auth_type=Authentication.No_Authentication, 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'', trailer=b'', **kwargs)[source]¶

Make (construct) packet data.

Parameters:

version (int) – OSPF version number.
type (Packet | IntEnum | aenum.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[aenum.IntEnum] | None) – Namespace for type.
type_reversed (bool) – Reverse namespace for type.
packet_length (int | None) – Packet length (header included). If not given, it is computed as 24 plus the length of payload. Give it explicitly when payload carries octets outside the OSPF packet, or pass those as trailer instead.
router_id (IPv4Address | str | bytes | bytearray) – Router ID.
area_id (IPv4Address | str | bytes | bytearray) – Area ID.
checksum (bytes) – Checksum.
auth_type (Authentication | IntEnum | aenum.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[aenum.IntEnum] | None) – Namespace for auth_type.
auth_type_reversed (bool) – Reverse namespace for auth_type.
auth_data (bytes | CryptographicAuthentication | CryptographicAuthentication | dict[str, Any]) – Authentication data: 8 octets, or, under cryptographic authentication, also a schema, a data model, or the dict form of a data model.
payload (bytes | ProtocolBase | Schema) – Payload data.
trailer (bytes) – Octets after the packet, outside the Packet Length, such as the message digest appended under cryptographic authentication (RFC 2328 Appendix D.4.3); written as is.
**kwargs (Any) – Arbitrary keyword arguments.

Return type:

OSPF

Returns:

Constructed packet data.

Raises:

ProtocolError – If auth_data is of an invalid type, is bytes that are not exactly 8 octets long, or is a dict missing a required key; or if packet_length is not an int in 0..65535.

Changed in version 1.5.0: packet_length is a new parameter before router_id, so a 1.4.x positional argument meant for router_id or a later parameter lands one parameter early (#1249).

classmethod _make_data(data)[source]¶

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)[source]¶

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 (CryptographicAuthentication) – parsed authentication data
Return type:: CryptographicAuthentication
Returns:: Parsed packet data.

_make_encrypt_auth(auth_data)[source]¶

Make Authentication field when Cryptographic Authentication is employed.

Parameters:: auth_data (bytes | CryptographicAuthentication | CryptographicAuthentication | dict[str, Any]) – Authentication data, as raw octets, a schema, a data model, or the dict form of a data model.
Return type:: CryptographicAuthentication
Returns:: Authentication schema.
Raises:: ProtocolError – If auth_data is of an invalid type, is bytes that are not exactly 8 octets long, or is a dict missing a required key.

classmethod __index__()[source]¶

Numeral registry index of the protocol.

Return type:: TransType
Returns:: Numeral registry index of the protocol in IANA.

_make_id_numbers(id)[source]¶

Make router and area IDs.

Parameters:: id (IPv4Address | str | bytes | bytearray) – ID.
Return type:: bytes
Returns:: ID bytes.
Raises:: FieldValueError – If id is a bool (see parse_ip_address()).

Notes

Latent rather than live: nothing in this module calls this method (make() builds router_id/area_id straight from its own arguments), so the only caller is a unit test. It is routed through parse_ip_address() anyway, so that a future caller passing a bool gets FieldValueError rather than a silent 0.0.0.1.

The description below uses self.__class__.__name__ rather than self.alias, because alias here reads self._version, which read() only assigns from the wire – unavailable to a construction-only instance that never went through read().

Header Schemas¶

class pcapkit.protocols.schema.application.ospf.OSPF(version=NO_VALUE, type=NO_VALUE, length=NO_VALUE, router_id=NO_VALUE, area_id=NO_VALUE, checksum=NO_VALUE, auth_type=NO_VALUE, auth_data=NO_VALUE, payload=NO_VALUE, trailer=NO_VALUE, *, __packet__=None, **kwargs)[source]¶

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 | CryptographicAuthentication = <SwitchField auth_data>¶: Authentication data.

payload: bytes = <PayloadField payload>¶: Payload.

trailer: bytes = <PayloadField trailer>¶: Octets captured past the Packet Length, such as the message digest that cryptographic authentication appends (RFC 2328 Appendix D.4.3); compare IPv4.trailer.

class pcapkit.protocols.schema.application.ospf.CryptographicAuthentication(reserved=NO_VALUE, key_id=NO_VALUE, len=NO_VALUE, seq=NO_VALUE, *, __packet__=None, **kwargs)[source]¶

Bases: Schema

Header schema for OSPF cryptographic authentication.

Added in version 1.5.0: Renamed from CrytographicAuthentication, which pcapkit.protocols.schema exported as OSPF_CrytographicAuthentication (#1090).

Removed in version 1.5.0: CrytographicAuthentication and OSPF_CrytographicAuthentication, with no alias (#1090).

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)[source]¶

Selector function for OSPF.auth_data field.

Parameters:: pkt (dict[str, Any]) – Packet data.
Return type:: FieldBase
Returns:: A SchemaField wrapped CryptographicAuthentication instance if OSPF.auth_type is 2, and a BytesField instance otherwise.

Data Models¶

class pcapkit.protocols.data.application.ospf.OSPF(version, type, len, router_id, area_id, chksum, autype)[source]¶

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 | CryptographicAuthentication¶: Authentication.

trailer: bytes¶: Octets captured past the Packet Length, present only when there are any.

class pcapkit.protocols.data.application.ospf.CryptographicAuthentication(reserved, key_id, len, seq)[source]¶

Bases: Data

Data model for OSPF cryptographic authentication.

Added in version 1.5.0: Renamed from CrytographicAuthentication, which pcapkit.protocols.data exported as OSPF_CrytographicAuthentication (#1090).

Removed in version 1.5.0: CrytographicAuthentication and OSPF_CrytographicAuthentication, with no alias (#1090).

reserved: bytes¶: The two reserved octets, as captured.

key_id: int¶: Key ID.

len: int¶: Authentication data length.

seq: int¶: Cryptographic sequence number.

Footnotes