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tls_lwt.ml
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tls_lwt.ml
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open Lwt.Infix
exception Tls_alert of Tls.Packet.alert_type
exception Tls_failure of Tls.Engine.failure
(* This really belongs just about anywhere else: generic unix name resolution. *)
let resolve host service =
let open Lwt_unix in
getprotobyname "tcp" >>= fun tcp ->
getaddrinfo host service [AI_PROTOCOL tcp.p_proto] >>= function
| [] ->
let msg = Printf.sprintf "no address for %s:%s" host service in
Lwt.reraise (Invalid_argument msg)
| ai::_ -> Lwt.return ai.ai_addr
module Lwt_cs = struct
let naked ~name f fd cs off len =
f fd cs off len >>= fun res ->
match Lwt_unix.getsockopt_error fd with
| None -> Lwt.return res
| Some err -> Lwt.reraise @@ Unix.Unix_error (err, name, "")
let write = naked ~name:"Tls_lwt.write" Lwt_unix.write
and read = naked ~name:"Tls_lwt.read" Lwt_unix.read
let rec write_full ?(off = 0) ?len fd buf =
let len = Option.value ~default:(String.length buf - off) len in
if len = 0 then
Lwt.return_unit
else
write fd (Bytes.unsafe_of_string buf) off len >>= fun written ->
write_full ~off:(off + written) ~len:(len - written) fd buf
let read fd buf = read fd buf 0 (Bytes.length buf)
end
module Lwt_fd = struct
type t = {
read : bytes -> int Lwt.t ;
write : string -> unit Lwt.t ;
close : unit -> unit Lwt.t ;
}
let read t cs = t.read cs
let write t cs = t.write cs
let close t = t.close ()
let of_fd fd =
let close () =
(* (partially) avoid double-closes by checking if the fd has already been closed *)
match Lwt_unix.state fd with
| Lwt_unix.Closed -> Lwt.return_unit
| Lwt_unix.Opened | Lwt_unix.Aborted _ -> Lwt_unix.close fd
in
{
read = Lwt_cs.read fd ;
write = Lwt_cs.write_full fd ;
close = close ;
}
let of_channels ic oc =
{
read = (fun bs -> Lwt_io.read_into ic bs 0 (Bytes.length bs)) ;
write = (Lwt_io.write oc) ;
close = (fun () -> Lwt_io.close oc <&> Lwt_io.close ic) ;
}
end
module Unix = struct
type t = {
fd : Lwt_fd.t ;
mutable state : [ `Active of Tls.Engine.state
| `Read_closed of Tls.Engine.state
| `Write_closed of Tls.Engine.state
| `Closed
| `Error of exn ] ;
mutable linger : string option ;
recv_buf : bytes ;
}
let half_close state mode =
match state, mode with
| `Active tls, `read -> `Read_closed tls
| `Active tls, `write -> `Write_closed tls
| `Active _, `read_write -> `Closed
| `Read_closed tls, `read -> `Read_closed tls
| `Read_closed _, (`write | `read_write) -> `Closed
| `Write_closed tls, `write -> `Write_closed tls
| `Write_closed _, (`read | `read_write) -> `Closed
| (`Closed | `Error _) as e, (`read | `write | `read_write) -> e
let inject_state tls = function
| `Active _ -> `Active tls
| `Read_closed _ -> `Read_closed tls
| `Write_closed _ -> `Write_closed tls
| (`Closed | `Error _) as e -> e
let safely th =
Lwt.catch
(fun () -> th >>= fun _ -> Lwt.return_unit)
(function
| Out_of_memory -> raise Out_of_memory
| _ -> Lwt.return_unit)
let (read_t, write_t) =
let recording_errors op t cs =
Lwt.catch
(fun () -> op t.fd cs)
(function
| Out_of_memory -> raise Out_of_memory
| exn -> (match t.state with
| `Error _ -> ()
| _ -> t.state <- `Error exn) ;
Lwt.reraise exn)
in
(recording_errors Lwt_fd.read, recording_errors Lwt_fd.write)
let when_some f = function None -> Lwt.return_unit | Some x -> f x
let rec read_react t =
let handle tls buf =
match Tls.Engine.handle_tls tls buf with
| Ok (state', eof, `Response resp, `Data data) ->
let state' = inject_state state' t.state in
let state' = Option.(value ~default:state' (map (fun `Eof -> half_close state' `read) eof)) in
t.state <- state' ;
safely (resp |> when_some (write_t t)) >|= fun () ->
`Ok data
| Error (fail, `Response resp) ->
t.state <- `Error (match fail with
| `Alert a -> Tls_alert a
| f -> Tls_failure f);
write_t t resp >>= fun () -> read_react t
in
match t.state with
| `Error e -> Lwt.reraise e
| `Closed
| `Read_closed _ -> Lwt.return `Eof
| _ ->
read_t t t.recv_buf >>= function
| 0 ->
t.state <- half_close t.state `read;
Lwt.return `Eof
| n ->
match t.state with
| `Error e -> Lwt.reraise e
| `Active tls | `Read_closed tls | `Write_closed tls ->
handle tls (String.sub (Bytes.unsafe_to_string t.recv_buf) 0 n)
| `Closed -> Lwt.return `Eof
let rec read t ?(off = 0) buf =
if off < 0 || off >= Bytes.length buf then
invalid_arg "offset must be >= 0 and < Bytes.length buf";
let writeout res =
let rlen = String.length res in
let n = min (Bytes.length buf - off) rlen in
Bytes.blit_string res 0 buf off n ;
t.linger <-
(if n < rlen then Some (String.sub res n (rlen - n)) else None) ;
Lwt.return n in
match t.linger with
| Some res -> writeout res
| None ->
read_react t >>= function
| `Eof -> Lwt.return 0
| `Ok None -> read t ~off buf
| `Ok (Some res) -> writeout res
let writev t css =
match t.state with
| `Error err -> Lwt.reraise err
| `Write_closed _ | `Closed -> Lwt.reraise @@ Invalid_argument "tls: closed socket"
| `Active tls | `Read_closed tls ->
match Tls.Engine.send_application_data tls css with
| Some (tls, tlsdata) ->
( t.state <- inject_state tls t.state ; write_t t tlsdata )
| None -> Lwt.reraise @@ Invalid_argument "tls: write: socket not ready"
let write t cs = writev t [cs]
(*
* XXX bad XXX
* This is a point that should particularly be protected from concurrent r/w.
* Doing this before a `t` is returned is safe; redoing it during rekeying is
* not, as the API client already sees the `t` and can mistakenly interleave
* writes while this is in progress.
* *)
let rec drain_handshake t =
let push_linger t mcs =
match (mcs, t.linger) with
| (None, _) -> ()
| (scs, None) -> t.linger <- scs
| (Some cs, Some l) -> t.linger <- Some (l ^ cs)
in
match t.state with
| `Active tls when not (Tls.Engine.handshake_in_progress tls) ->
Lwt.return t
| _ ->
read_react t >>= function
| `Eof -> Lwt.reraise End_of_file
| `Ok cs -> push_linger t cs ; drain_handshake t
let reneg ?authenticator ?acceptable_cas ?cert ?(drop = true) t =
match t.state with
| `Error err -> Lwt.reraise err
| `Closed | `Read_closed _ | `Write_closed _ ->
Lwt.reraise @@ Invalid_argument "tls: closed socket"
| `Active tls ->
match Tls.Engine.reneg ?authenticator ?acceptable_cas ?cert tls with
| None -> Lwt.reraise @@ Invalid_argument "tls: can't renegotiate"
| Some (tls', buf) ->
if drop then t.linger <- None ;
t.state <- inject_state tls' t.state ;
write_t t buf >>= fun () ->
drain_handshake t >>= fun _ ->
Lwt.return_unit
let key_update ?request t =
match t.state with
| `Error err -> Lwt.reraise err
| `Write_closed _ | `Closed -> Lwt.reraise @@ Invalid_argument "tls: closed socket"
| `Active tls | `Read_closed tls ->
match Tls.Engine.key_update ?request tls with
| Error f -> Lwt.reraise @@ Invalid_argument (Format.asprintf "tls: can't update key: %a" Tls.Engine.pp_failure f)
| Ok (tls', buf) ->
t.state <- inject_state tls' t.state ;
write_t t buf
let shutdown t mode =
(match mode with
| `read -> Lwt.return_unit
| `write | `read_write ->
match t.state with
| `Active tls | `Read_closed tls ->
let tls', buf = Tls.Engine.send_close_notify tls in
t.state <- inject_state tls' (half_close t.state `write) ;
write_t t buf
| _ -> Lwt.return_unit) >>= fun () ->
t.state <- half_close t.state mode;
match t.state with
| `Closed | `Error _ -> safely (Lwt_fd.close t.fd)
| _ -> Lwt.return_unit
let close t = shutdown t `read_write
let server_of_fd config fd =
drain_handshake {
state = `Active (Tls.Engine.server config) ;
fd = fd ;
linger = None ;
recv_buf = Bytes.create 4096
}
let server_of_channels config (ic, oc) =
server_of_fd config (Lwt_fd.of_channels ic oc)
let server_of_fd config fd =
server_of_fd config (Lwt_fd.of_fd fd)
let client_of_fd config ?host fd =
let config' = match host with
| None -> config
| Some host -> Tls.Config.peer config host
in
let (tls, init) = Tls.Engine.client config' in
let t = {
state = `Active tls ;
fd = fd ;
linger = None ;
recv_buf = Bytes.create 4096
}
in
write_t t init >>= fun () ->
drain_handshake t
let client_of_channels config ?host (ic, oc) =
client_of_fd config ?host (Lwt_fd.of_channels ic oc)
let client_of_fd config ?host fd =
client_of_fd config ?host (Lwt_fd.of_fd fd)
let accept conf fd =
Lwt_unix.accept fd >>= fun (fd', addr) ->
Lwt.catch (fun () -> server_of_fd conf fd' >|= fun t -> (t, addr))
(function
| Out_of_memory -> raise Out_of_memory
| exn -> safely (Lwt_unix.close fd') >>= fun () -> Lwt.reraise exn)
let connect conf (host, port) =
resolve host (string_of_int port) >>= fun addr ->
let fd = Lwt_unix.(socket (Unix.domain_of_sockaddr addr) SOCK_STREAM 0) in
Lwt.catch (fun () ->
let host =
Result.to_option
(Result.bind (Domain_name.of_string host) Domain_name.host)
in
Lwt_unix.connect fd addr >>= fun () -> client_of_fd conf ?host fd)
(function
| Out_of_memory -> raise Out_of_memory
| exn -> safely (Lwt_unix.close fd) >>= fun () -> Lwt.reraise exn)
let read_bytes t bs off len =
let buf = Bytes.create len in
read t buf >|= fun n ->
let to_copy = min n len in
Lwt_bytes.blit_from_bytes buf 0 bs off to_copy;
to_copy
let write_bytes t bs off len =
let buf = Bytes.create len in
Lwt_bytes.blit_to_bytes bs off buf 0 len;
write t (Bytes.unsafe_to_string buf)
let epoch t =
match t.state with
| `Active tls | `Read_closed tls | `Write_closed tls -> Tls.Engine.epoch tls
| `Closed | `Error _ -> Error ()
end
type ic = Lwt_io.input_channel
type oc = Lwt_io.output_channel
let of_t ?close t =
let close = match close with
| Some f -> (fun () -> Unix.safely (f ()))
| None -> (fun () -> Unix.(safely (close t)))
in
(Lwt_io.make ~close ~mode:Lwt_io.Input (Unix.read_bytes t)),
(Lwt_io.make ~close ~mode:Lwt_io.Output @@
fun a b c -> Unix.write_bytes t a b c >>= fun () -> Lwt.return c)
let accept_ext conf fd =
Unix.accept conf fd >|= fun (t, peer) -> (of_t t, peer)
and connect_ext conf addr =
Unix.connect conf addr >|= of_t
let accept certificate fd =
match Tls.Config.server ~certificates:certificate () with
| Ok config -> accept_ext config fd >|= fun w -> Ok w
| Error _ as e -> Lwt.return e
and connect authenticator addr =
match Tls.Config.client ~authenticator () with
| Ok config -> connect_ext config addr >|= fun w -> Ok w
| Error _ as e -> Lwt.return e
(* Boot the entropy loop at module init time. *)
let () = Mirage_crypto_rng_lwt.initialize (module Mirage_crypto_rng.Fortuna)
let () =
Printexc.register_printer (function
| Tls_alert typ ->
Some ("TLS alert from peer: " ^ Tls.Packet.alert_type_to_string typ)
| Tls_failure f ->
Some ("TLS failure: " ^ Tls.Engine.string_of_failure f)
| _ -> None)