erldns_handler behaviour (erldns v10.5.3)

View Source

The module that handles the resolution of a single DNS question.

The meat of the resolution occurs in erldns_resolver:resolve/3

Configuration

{erldns, [
    {packet_handlers, [
        {my_custom_handler_module, [?DNS_TYPE_A, ?DNS_TYPE_AAAA], 3}
    ]},
]}

Record types can be given in their integer codes or binary representations, meaning, the following are equivalent:

    {my_custom_handler_module, [?DNS_TYPE_A, ?DNS_TYPE_AAAA], 3}
    ...
    {my_custom_handler_module, [?DNS_TYPE_A, ~"AAAA"], 3}
    ...
    {my_custom_handler_module, [~"A", ~"AAAA"], 3}

The minimum supported version is 2.

Version 2's handler signature is

handle(dns:message(), dns:labels(), dns:type(), [dns:rr()]) -> [dns:rr()]

Version 3's handler signature is

handle(dns:dname(), dns:type(), [dns:rr()], dns:message()) -> [dns:rr()].

Summary

Types

handler()
handler_config()
nsec_type_mapper()
state()
versioned_handler()

Callbacks

filter/1

Filter the given record set, returning replacement records.

handle/4

Filter out records not related to the given handler

nsec_rr_type_mapper/2

Map handler's record types to NSEC bit types.

Functions

call_filters(Records)

Filter records through registered handlers.

call_handlers(Message, QLabels, QType, Records)

Call all registered handlers.

call_map_nsec_rr_types(Types)
call_map_nsec_rr_types(QType, Types)
get_versioned_handlers()

Get all registered handlers along with the DNS types they handle and associated versions

register_handler(RecordTypes, Module)

Register a record handler with the default version of 1

register_handler(RecordTypes, Module, Version)

Register a record handler with version

register_nsec_type_mapper(RecordTypes, MapperFun)

Register a standalone NSEC type mapper for specific record types.

start_link()

Start the handler registry process

unregister_nsec_type_mapper(RecordTypes, MapperFun)

Unregister NSEC type mappers for specific record types.

Types

handler()

-type handler() :: {module(), [dns:type()]}.

handler_config()

-type handler_config() :: {module(), [dns:type()], integer()}.

nsec_type_mapper()

-type nsec_type_mapper() :: {[dns:type()], fun((dns:type(), dns:type()) -> [dns:type()])}.

state()

-opaque state()

versioned_handler()

-type versioned_handler() ::
          {fun((dns:message(), dns:labels(), dns:type(), [dns:rr()]) -> [dns:rr()]),
           fun(([dns:rr()]) -> [dns:rr()]),
           fun((dns:type(), dns:type()) -> [dns:type()]),
           module(),
           [dns:type()],
           integer()}.

Callbacks

filter/1

-callback filter([dns:rr()]) -> [dns:rr()].

Filter the given record set, returning replacement records.

handle/4

-callback handle(dns:message(), dns:labels(), dns:type(), [dns:rr()]) -> [dns:rr()].

Filter out records not related to the given handler

nsec_rr_type_mapper/2

-callback nsec_rr_type_mapper(dns:type(), dns:type()) -> [dns:type()].

Map handler's record types to NSEC bit types.

Functions

call_filters(Records)

-spec call_filters([dns:rr()]) -> [dns:rr()].

Filter records through registered handlers.

call_handlers(Message, QLabels, QType, Records)

-spec call_handlers(dns:message(), dns:labels(), dns:type(), [dns:rr()]) -> [dns:rr()].

Call all registered handlers.

call_map_nsec_rr_types(Types)

-spec call_map_nsec_rr_types([dns:type()]) -> [dns:type()].

call_map_nsec_rr_types(QType, Types)

-spec call_map_nsec_rr_types(dns:type(), [dns:type()]) -> [dns:type()].

get_versioned_handlers()

-spec get_versioned_handlers() -> [versioned_handler()].

Get all registered handlers along with the DNS types they handle and associated versions

register_handler(RecordTypes, Module)

-spec register_handler([dns:type()], module()) -> ok.

Register a record handler with the default version of 1

register_handler(RecordTypes, Module, Version)

-spec register_handler([dns:type()], module(), integer()) -> ok.

Register a record handler with version

register_nsec_type_mapper(RecordTypes, MapperFun)

-spec register_nsec_type_mapper([dns:type()], fun((dns:type(), dns:type()) -> [dns:type()])) -> ok.

Register a standalone NSEC type mapper for specific record types.

This allows pipeline modules to provide NSEC type mapping without implementing the full handler interface (handle/4, filter/1).

Example:

erldns_handler:register_nsec_type_mapper([30003], fun my_module:nsec_rr_type_mapper/2)

start_link()

-spec start_link() -> gen_server:start_ret().

Start the handler registry process

unregister_nsec_type_mapper(RecordTypes, MapperFun)

-spec unregister_nsec_type_mapper([dns:type()], fun((dns:type(), dns:type()) -> [dns:type()])) -> ok.

Unregister NSEC type mappers for specific record types.