(* (c) 2018 Hannes Mehnert, all rights reserved *)

type t
(** The type of a DNS resolver. *)

type feature =
  [ `Dnssec | `Qname_minimisation | `Opportunistic_tls_authoritative ]

val create : ?record_clients:bool -> ?cache_size:int ->
  ?ip_protocol:[ `Both | `Ipv4_only | `Ipv6_only ] ->
  feature list ->
  int64 -> (int -> string) -> Dns_server.Primary.s -> t
(** [create ~record_clients ~cache_size ~ip_protocol features now rng primary]
    creates the value of a resolver, pre-filled with root NS and their IP
    addresses. If [ip_protocol] is provided, and set to [`V4_only], only IPv4
    packets will be emitted. If [`V6_only] is set, only IPv6 packets will be
    emitted. If [`Both] (the default), either IPv4 and IPv6 packets are
    emitted. If [record_clients] is true (the default), the metrics of
    the resolver will include the amount of clients.  This keeps a set of
    Ipaddr.t of all clients around, which may use some memory if it is a public
    resolver.

    Some features can be specified, whether DNSSec validation should be done,
    whether query name minimisation should be done, and whether opportunistic
    encryption using TLS to the authoritative should be done.
*)

val features : t -> feature list

val handle_buf : t -> Ptime.t -> int64 -> bool -> Dns.proto -> Ipaddr.t ->
  int -> string ->
  t * (Dns.proto * Ipaddr.t * int * int32 * string) list
    * (Dns.proto * Ipaddr.t * string) list
(** [handle_buf t now ts query_or_reply proto sender source-port buf] handles
   resolution of [buf], which leads to a new [t], a list of answers to be
    transmitted (quintuple of protocol, ip address, port, minimum ttl, buffer),
    and a list of queries (triple of protocol, ip address, buffer). *)

val query_root : t -> int64 -> Dns.proto ->
  t * (Dns.proto * Ipaddr.t * string)
(** [query_root t now proto] potentially requests an update of the root
   zone. Best invoked by a regular timer. *)

val timer : t -> int64 ->
  t * (Dns.proto * Ipaddr.t * int * int32 * string) list
    * (Dns.proto * Ipaddr.t * string) list
(** [timer t now] potentially retransmits DNS requests and/or sends NXDomain
    answers. *)

val primary_data : t -> Dns_trie.t
(** [primary_data t] is the DNS trie of the primary. *)

val with_primary_data : t -> Ptime.t -> int64 -> Dns_trie.t -> t * (Ipaddr.t * string list) list
(** [with_primary_data t now ts data] is a pair [(t', outs)] where [t'] is [t]
    updated with the [data] DNS trie, and [outs] is the data to send out (if
    any). *)