(* Copyright (C) 2016, Thomas Leonard <thomas.leonard@unikernel.com>
   See the README file for details. *)

(** The ethernet networks connecting us to our client AppVMs.
    Note: each AppVM is on a point-to-point link, each link being considered to be a separate Ethernet network. *)

open Fw_utils

type t
(** A collection of clients. *)

type host =
  [ `Client of client_link
  | `Firewall
  | `External of Ipaddr.t ]
(* Note: Qubes does not allow us to distinguish between an external address and a
   disconnected client.
   See: https://github.com/talex5/qubes-mirage-firewall/issues/9#issuecomment-246956850 *)

val create : client_gw:Ipaddr.V4.t -> t
(** [create ~client_gw] is a network of client machines.
    Qubes will have configured the client machines to use [client_gw] as their default gateway. *)

val add_client : t -> client_link -> unit Lwt.t
(** [add_client t client] registers a new client. If a client with this IP address is already registered,
    it waits for [remove_client] to be called on that before adding the new client and returning. *)

val remove_client : t -> client_link -> unit

val client_gw : t -> Ipaddr.V4.t

val classify : t -> Ipaddr.t -> host
val resolve : t -> host -> Ipaddr.t

val lookup : t -> Ipaddr.V4.t -> client_link option
(** [lookup t addr] is the client with IP address [addr], if connected. *)

module ARP : sig
  (** We already know the correct mapping of IP addresses to MAC addresses, so we never
      allow clients to update it. We log a warning if a client attempts to set incorrect
      information. *)

  type arp
  (** An ARP-responder for one client. *)

  val create : net:t -> client_link -> arp
  (** [create ~net client_link] is an ARP responder for [client_link].
      It answers only for the client's gateway address. *)

  val input : arp -> Arp_packet.t -> Arp_packet.t option
  (** Process one ethernet frame containing an ARP message.
      Returns a response frame, if one is needed. *)
end