mirror of
https://github.com/mirage/qubes-mirage-firewall.git
synced 2024-09-28 19:55:39 +00:00
59 lines
2.0 KiB
OCaml
59 lines
2.0 KiB
OCaml
open Lwt.Infix
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module Transport (R : Mirage_random.S) (C : Mirage_clock.MCLOCK) = struct
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type +'a io = 'a Lwt.t
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type io_addr = Ipaddr.V4.t * int
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type ns_addr = Dns.proto * io_addr list
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type stack = Router.t * (src_port:int -> dst:Ipaddr.V4.t -> dst_port:int -> Cstruct.t -> (unit, [ `Msg of string ]) result Lwt.t) * (Udp_packet.t * Cstruct.t) Lwt_mvar.t
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type t = {
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nameservers : ns_addr ;
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stack : stack ;
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timeout_ns : int64 ;
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}
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type context = { t : t ; timeout_ns : int64 ref; mutable src_port : int }
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let nameservers t = t.nameservers
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let rng = R.generate ?g:None
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let clock = C.elapsed_ns
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let create ?(nameservers = `Udp, [(Ipaddr.V4.of_string_exn "91.239.100.100", 53)]) ~timeout stack =
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{ nameservers ; stack ; timeout_ns = timeout }
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let with_timeout ctx f =
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let timeout = OS.Time.sleep_ns !(ctx.timeout_ns) >|= fun () -> Error (`Msg "DNS request timeout") in
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let start = clock () in
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Lwt.pick [ f ; timeout ] >|= fun result ->
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let stop = clock () in
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ctx.timeout_ns := Int64.sub !(ctx.timeout_ns) (Int64.sub stop start);
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result
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let connect (t : t) = Lwt.return (Ok { t ; timeout_ns = ref t.timeout_ns ; src_port = 0 })
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let send (ctx : context) buf : (unit, [> `Msg of string ]) result Lwt.t =
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let open Router in
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let open My_nat in
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let nslist = snd ctx.t.nameservers in
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let dst, dst_port = List.hd nslist in
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let router, send_udp, _ = ctx.t.stack in
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let src_port = Ports.pick_free_port ~consult:router.ports.nat_udp router.ports.dns_udp in
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ctx.src_port <- src_port;
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with_timeout ctx (send_udp ~src_port ~dst ~dst_port buf >|= Rresult.R.open_error_msg)
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let recv ctx =
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let open Router in
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let open My_nat in
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let router, _, answers = ctx.t.stack in
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with_timeout ctx
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(Lwt_mvar.take answers >|= fun (_, dns_response) -> Ok dns_response) >|= fun result ->
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router.ports.dns_udp := Ports.remove ctx.src_port !(router.ports.dns_udp);
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result
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let close _ = Lwt.return_unit
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let bind = Lwt.bind
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let lift = Lwt.return
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end
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