Message EDNS Options

EDNS allows for larger messages and also provides an extension mechanism for the protocol. EDNS options are typed data, and are treated much like Rdata. For example, if dnspython encounters the EDNS ECS option code when parsing a DNS wire format message, it will create a dns.edns.ECSOption object to represent it.

class dns.edns.OptionType(value)[source]: EDNS option type codes

dns.edns.NSID = OptionType.NSID: EDNS option type codes

dns.edns.DAU = OptionType.DAU: EDNS option type codes

dns.edns.DHU = OptionType.DHU: EDNS option type codes

dns.edns.N3U = OptionType.N3U: EDNS option type codes

dns.edns.ECS = OptionType.ECS: EDNS option type codes

dns.edns.EXPIRE = OptionType.EXPIRE: EDNS option type codes

dns.edns.COOKIE = OptionType.COOKIE: EDNS option type codes

dns.edns.KEEPALIVE = OptionType.KEEPALIVE: EDNS option type codes

dns.edns.PADDING = OptionType.PADDING: EDNS option type codes

dns.edns.CHAIN = OptionType.CHAIN: EDNS option type codes

class dns.edns.Option(otype: OptionType | str)[source]

Base class for all EDNS option types.

Initialize an option.

Parameters:: otype (dns.edns.OptionType) – The option type.

classmethod from_wire_parser(otype: OptionType, parser: Parser) → Option[source]

Build an EDNS option object from wire format.

Parameters:

otype (dns.edns.OptionType) – The option type.
parser (dns.wire.Parser) – The parser, restricted to the option length.

Return type:

dns.edns.Option

to_generic() → GenericOption[source]

Create a dns.edns.GenericOption equivalent of this option.

Return type:: dns.edns.GenericOption

to_wire(file: Any | None = None) → bytes | None[source]

Convert an option to wire format.

Return type:: bytes or None

class dns.edns.GenericOption(otype: OptionType | str, data: bytes | str)[source]

Generic Option Class

This class is used for EDNS option types for which we have no better implementation.

Initialize an option.

Parameters:: otype (dns.edns.OptionType) – The option type.

classmethod from_wire_parser(otype: OptionType | str, parser: Parser) → Option[source]

Build an EDNS option object from wire format.

Parameters:

otype (dns.edns.OptionType) – The option type.
parser (dns.wire.Parser) – The parser, restricted to the option length.

Return type:

dns.edns.Option

to_generic() → GenericOption[source]

Create a dns.edns.GenericOption equivalent of this option.

Return type:: dns.edns.GenericOption

to_wire(file: Any | None = None) → bytes | None[source]

Convert an option to wire format.

Return type:: bytes or None

class dns.edns.ECSOption(address: str, srclen: int | None = None, scopelen: int = 0)[source]

EDNS Client Subnet (ECS, RFC7871)

Initialize an ECSOption.

Parameters:

address (str) – The client address information.
srclen (int or None) – The source prefix length (leftmost number of bits of the address to be used for the lookup). Defaults to 24 for IPv4 and 56 for IPv6.
scopelen (int) – The scope prefix length. Must be 0 in queries; should be set in responses.

static from_text(text: str) → Option[source]

Convert a string into a dns.edns.ECSOption

text, a str, the text form of the option.

Returns a dns.edns.ECSOption.

Examples:

>>> import dns.edns
>>>
>>> # basic example
>>> dns.edns.ECSOption.from_text('1.2.3.4/24')
>>>
>>> # also understands scope
>>> dns.edns.ECSOption.from_text('1.2.3.4/24/32')
>>>
>>> # IPv6
>>> dns.edns.ECSOption.from_text('2001:4b98::1/64/64')
>>>
>>> # it understands results from `dns.edns.ECSOption.to_text()`
>>> dns.edns.ECSOption.from_text('ECS 1.2.3.4/24/32')

classmethod from_wire_parser(otype: OptionType | str, parser: Parser) → Option[source]

Build an EDNS option object from wire format.

Parameters:

otype (dns.edns.OptionType) – The option type.
parser (dns.wire.Parser) – The parser, restricted to the option length.

Return type:

dns.edns.Option

to_wire(file: Any | None = None) → bytes | None[source]

Convert an option to wire format.

Return type:: bytes or None

class dns.edns.EDECode(value)[source]: Extended DNS Error (EDE) codes

class dns.edns.EDEOption(code: EDECode | str, text: str | None = None)[source]

Extended DNS Error (EDE, RFC8914)

Initialize an EDEOption.

Parameters:

code (dns.edns.EDECode or str) – The info code of the extended error.
text (str or None) – Additional information about the error.

classmethod from_wire_parser(otype: OptionType | str, parser: Parser) → Option[source]

Build an EDNS option object from wire format.

Parameters:

otype (dns.edns.OptionType) – The option type.
parser (dns.wire.Parser) – The parser, restricted to the option length.

Return type:

dns.edns.Option

to_wire(file: Any | None = None) → bytes | None[source]

Convert an option to wire format.

Return type:: bytes or None

class dns.edns.NSIDOption(nsid: bytes)[source]

Initialize an option.

Parameters:: otype (dns.edns.OptionType) – The option type.

classmethod from_wire_parser(otype: OptionType | str, parser: Parser) → Option[source]

Build an EDNS option object from wire format.

Parameters:

otype (dns.edns.OptionType) – The option type.
parser (dns.wire.Parser) – The parser, restricted to the option length.

Return type:

dns.edns.Option

to_wire(file: Any = None) → bytes | None[source]

Convert an option to wire format.

Return type:: bytes or None

class dns.edns.CookieOption(client: bytes, server: bytes)[source]

Initialize an option.

Parameters:: otype (dns.edns.OptionType) – The option type.

classmethod from_wire_parser(otype: OptionType | str, parser: Parser) → Option[source]

Build an EDNS option object from wire format.

Parameters:

otype (dns.edns.OptionType) – The option type.
parser (dns.wire.Parser) – The parser, restricted to the option length.

Return type:

dns.edns.Option

to_wire(file: Any = None) → bytes | None[source]

Convert an option to wire format.

Return type:: bytes or None

class dns.edns.ReportChannelOption(agent_domain: Name)[source]

Initialize an option.

Parameters:: otype (dns.edns.OptionType) – The option type.

classmethod from_wire_parser(otype: OptionType | str, parser: Parser) → Option[source]

Build an EDNS option object from wire format.

Parameters:

otype (dns.edns.OptionType) – The option type.
parser (dns.wire.Parser) – The parser, restricted to the option length.

Return type:

dns.edns.Option

to_wire(file: Any = None) → bytes | None[source]

Convert an option to wire format.

Return type:: bytes or None

class dns.edns.EDEExtraTextLanguageOption(language: str)[source]

Extended DNS Error EXTRA-TEXT language (EDE-EXTRA-TEXT-LANGUAGE)

Initialize an EDEExtraTextLanguageOption.

Parameters:: language (str) – The language of EXTRA-TEXT in the EDE option.

classmethod from_wire_parser(otype: OptionType | str, parser: Parser) → Option[source]

Build an EDNS option object from wire format.

Parameters:

otype (dns.edns.OptionType) – The option type.
parser (dns.wire.Parser) – The parser, restricted to the option length.

Return type:

dns.edns.Option

to_wire(file: Any = None) → bytes | None[source]

Convert an option to wire format.

Return type:: bytes or None

class dns.edns.FilteringContactOption(contact: str)[source]

Filtering contact (FILTERING-CONTACT)

Initialize a FilteringContactOption.

Parameters:: contact (str) – A filtering contact URI as a string.

classmethod from_wire_parser(otype: OptionType | str, parser: Parser) → Option[source]

Build an EDNS option object from wire format.

Parameters:

otype (dns.edns.OptionType) – The option type.
parser (dns.wire.Parser) – The parser, restricted to the option length.

Return type:

dns.edns.Option

to_wire(file: Any = None) → bytes | None[source]

Convert an option to wire format.

Return type:: bytes or None

class dns.edns.FilteringOrganizationOption(organization: str)[source]

Filtering organization (FILTERING-ORGANIZATION)

Initialize a FilteringOrganizationOption.

Parameters:: organization (str) – The filtering organization.

classmethod from_wire_parser(otype: OptionType | str, parser: Parser) → Option[source]

Build an EDNS option object from wire format.

Parameters:

otype (dns.edns.OptionType) – The option type.
parser (dns.wire.Parser) – The parser, restricted to the option length.

Return type:

dns.edns.Option

to_wire(file: Any = None) → bytes | None[source]

Convert an option to wire format.

Return type:: bytes or None

class dns.edns.FilteringDBOption(db: str)[source]

Filtering DB (FILTERING-DB)

Initialize a FilteringDBOption.

Parameters:: db (str) – The filtering database containing the identifier, name, or description of the filtering database against which a matched query caused the filtering to occur.

classmethod from_wire_parser(otype: OptionType | str, parser: Parser) → Option[source]

Build an EDNS option object from wire format.

Parameters:

otype (dns.edns.OptionType) – The option type.
parser (dns.wire.Parser) – The parser, restricted to the option length.

Return type:

dns.edns.Option

to_wire(file: Any = None) → bytes | None[source]

Convert an option to wire format.

Return type:: bytes or None

dns.edns.get_option_class(otype: OptionType) → Any[source]

Return the class for the specified option type.

The GenericOption class is used if a more specific class is not known.

dns.edns.option_from_wire_parser(otype: OptionType | str, parser: Parser) → Option[source]

Build an EDNS option object from wire format.

Parameters:

otype (int or dns.edns.OptionType) – The option type.
parser (dns.wire.Parser) – The parser, restricted to the option length.

Return type:

dns.edns.Option

dns.edns.option_from_wire(otype: OptionType | str, wire: bytes, current: int, olen: int) → Option[source]

Build an EDNS option object from wire format.

Parameters:

otype (int or dns.edns.OptionType) – The option type.
wire (bytes) – The wire-format message.
current (int) – The offset in wire of the beginning of the rdata.
olen (int) – The length of the wire-format option data.

Return type:

dns.edns.Option

dns.edns.register_type(implementation: Any, otype: OptionType) → None[source]

Register the implementation of an option type.

Parameters:

implementation – A subclass of dns.edns.Option.
otype (dns.edns.OptionType) – The option type.