Add the miou implementation (#503)

* Add the Miou implementation of TLS

miou/dune

@@ -0,0 +1,4 @@
+(library
+ (name tls_miou_unix)
+ (public_name tls-miou-unix)
+ (libraries miou.unix tls))

miou/tests/dune

@@ -0,0 +1,15 @@
+(test
+ (name fuzz)
+ (package tls-miou-unix)
+ (libraries
+   mirage-crypto-rng-miou-unix
+   ohex
+   rresult
+   ptime
+   ptime.clock.os
+   crowbar
+   hxd.core
+   hxd.string
+   tls-miou-unix)
+ (instrumentation
+  (backend bisect_ppx)))

miou/tests/fuzz.ml

@@ -0,0 +1,338 @@
+let rec random_path ?(tries = 10) fmt =
+  if tries <= 0 then failwith "Impossible to generate an available random path";
+  let res = Bytes.create 6 in
+  for i = 0 to Bytes.length res - 1 do
+    let chr =
+      match Random.int (10 + 26 + 26) with
+      | n when n < 10 -> Char.chr (Char.code '0' + n)
+      | n when n < 10 + 26 -> Char.chr (Char.code 'a' + n - 10)
+      | n -> Char.chr (Char.code 'A' + n - 10 - 26)
+    in
+    Bytes.set res i chr
+  done;
+  let path = Fmt.str fmt (Bytes.unsafe_to_string res) in
+  if Sys.file_exists path then random_path ~tries:(pred tries) fmt else path
+
+let unlink_if_exists path =
+  try Unix.unlink path with Unix.Unix_error (Unix.ENOENT, _, _) -> ()
+
+let bind_and_listen ?(backlog = 16) () =
+  let tmp = random_path "socket-%s.socket" in
+  unlink_if_exists tmp;
+  let socket = Unix.socket ~cloexec:true Unix.PF_UNIX Unix.SOCK_STREAM 0 in
+  let addr = Unix.ADDR_UNIX tmp in
+  Unix.bind socket addr;
+  Unix.listen socket backlog;
+  (Miou_unix.of_file_descr ~non_blocking:true socket, addr, tmp)
+
+module Ca = struct
+  open Rresult
+
+  let prefix =
+    X509.Distinguished_name.
+      [ Relative_distinguished_name.singleton (CN "Fuzzer") ]
+
+  let cacert_dn =
+    X509.Distinguished_name.(
+      prefix
+      @ [ Relative_distinguished_name.singleton (CN "Ephemeral CA for fuzzer") ])
+
+  let cacert_lifetime = Ptime.Span.v (365, 0L)
+
+  let make domain_name seed =
+    Domain_name.of_string domain_name >>= Domain_name.host
+    >>= fun domain_name ->
+    let private_key =
+      let seed = Base64.decode_exn ~pad:false seed in
+      let g = Mirage_crypto_rng.(create ~seed (module Fortuna)) in
+      Mirage_crypto_pk.Rsa.generate ~g ~bits:2048 ()
+    in
+    let valid_from = Ptime.v (Ptime_clock.now_d_ps ()) in
+    Ptime.add_span valid_from cacert_lifetime
+    |> Option.to_result ~none:(R.msgf "End time out of range")
+    >>= fun valid_until ->
+    X509.Signing_request.create cacert_dn (`RSA private_key) >>= fun ca_csr ->
+    let extensions =
+      let open X509.Extension in
+      let key_id =
+        X509.Public_key.id X509.Signing_request.((info ca_csr).public_key)
+      in
+      empty
+      |> add Subject_alt_name
+           ( true,
+             X509.General_name.(
+               singleton DNS [ Domain_name.to_string domain_name ]) )
+      |> add Basic_constraints (true, (false, None))
+      |> add Key_usage
+           (true, [ `Digital_signature; `Content_commitment; `Key_encipherment ])
+      |> add Subject_key_id (false, key_id)
+    in
+    X509.Signing_request.sign ~valid_from ~valid_until ~extensions
+      ca_csr (`RSA private_key) cacert_dn
+    |> R.reword_error (R.msgf "%a" X509.Validation.pp_signature_error)
+    >>= fun certificate ->
+    let fingerprint = X509.Certificate.fingerprint `SHA256 certificate in
+    let time () = Some (Ptime_clock.now ()) in
+    let authenticator =
+      X509.Authenticator.cert_fingerprint ~time ~hash:`SHA256
+        ~fingerprint
+    in
+    Ok (certificate, `RSA private_key, authenticator)
+end
+
+let fuzz_coop = "fuzz.coop"
+let mutex = Miou.Mutex.create ()
+let epr fmt = Miou.Mutex.protect mutex @@ fun () -> Fmt.epr fmt
+
+type operation =
+  | Send of string
+  | Recv of int
+  | Shutdown of [ `read | `write ]
+  | Close
+  | Noop
+
+module Stop = struct
+  type t = {
+    mutex : Miou.Mutex.t;
+    condition : Miou.Condition.t;
+    mutable stop : bool;
+  }
+
+  let create () =
+    let mutex = Miou.Mutex.create () in
+    let condition = Miou.Condition.create () in
+    { mutex; condition; stop = false }
+
+  let stop t =
+    Miou.Mutex.protect t.mutex @@ fun () ->
+    t.stop <- true;
+    Miou.Condition.broadcast t.condition
+
+  let wait t =
+    Miou.Mutex.protect t.mutex @@ fun () ->
+    while t.stop = false do
+      Miou.Condition.wait t.condition t.mutex
+    done
+end
+
+let inhibit fn = try fn () with _exn -> ()
+
+let run ~role:_ actions tls =
+  let rec go buf tls = function
+    | [] -> Buffer.contents buf
+    | Noop :: actions ->
+        Miou.yield ();
+        go buf tls actions
+    | Send str :: actions ->
+        Tls_miou_unix.write tls str;
+        go buf tls actions
+    | Close :: actions ->
+        Tls_miou_unix.close tls;
+        go buf tls actions
+    | Shutdown cmd :: actions ->
+        Tls_miou_unix.shutdown tls (cmd :> [ `read | `write | `read_write ]);
+        go buf tls actions
+    | Recv len :: actions ->
+        let tmp = Bytes.make len '\000' in
+        Tls_miou_unix.really_read tls tmp;
+        Buffer.add_subbytes buf tmp 0 len;
+        go buf tls actions
+  in
+  let buf = Buffer.create 0x100 in
+  try go buf tls actions with
+  | End_of_file | Tls_miou_unix.Closed_by_peer | Tls_miou_unix.Tls_alert _
+  | Tls_miou_unix.Tls_failure _ ->
+      inhibit (fun () -> Miou_unix.close (Tls_miou_unix.file_descr tls));
+      Buffer.contents buf
+  | exn ->
+      inhibit (fun () -> Miou_unix.close (Tls_miou_unix.file_descr tls));
+      raise exn
+
+let run_client ~to_client:actions cfg addr =
+  let domain = Unix.domain_of_sockaddr addr in
+  let socket = Unix.socket ~cloexec:true domain Unix.SOCK_STREAM 0 in
+  Unix.connect socket addr;
+  let fd = Miou_unix.of_file_descr ~non_blocking:true socket in
+  let tls = Tls_miou_unix.client_of_fd cfg fd in
+  let finally () =
+    inhibit (fun () -> Unix.close socket)
+  in
+  Fun.protect ~finally @@ fun () -> run ~role:"client" actions tls
+
+let rec cleanup orphans clients =
+  match Miou.care orphans with
+  | None | Some None -> clients
+  | Some (Some prm) ->
+      let clients = Miou.await prm :: clients in
+      cleanup orphans clients
+
+let rec terminate orphans clients =
+  match Miou.care orphans with
+  | None -> List.rev clients
+  | Some None ->
+      Miou.yield ();
+      terminate orphans clients
+  | Some (Some prm) ->
+      let clients = Miou.await prm :: clients in
+      terminate orphans clients
+
+exception Stop
+
+let run_server ~to_server:actions ~stop fd cfg =
+  let rec go orphans clients =
+    let clients = cleanup orphans clients in
+    let accept = Miou.async @@ fun () -> Miou_unix.accept ~cloexec:true fd in
+    let stop =
+      Miou.async @@ fun () ->
+      Stop.wait stop;
+      raise Stop
+    in
+    match Miou.await_first [ accept; stop ] with
+    | Error _ ->
+        inhibit (fun () -> Miou_unix.close fd);
+        terminate orphans clients
+    | Ok (fd, _) ->
+        ignore
+          ( Miou.async ~orphans @@ fun () ->
+            match Tls_miou_unix.server_of_fd cfg fd with
+            | tls ->
+                let str = run ~role:"server" actions tls in
+                inhibit (fun () -> Miou_unix.close fd); str
+            | exception _ ->
+                Miou_unix.close fd;
+                String.empty );
+        go orphans clients
+  in
+  go (Miou.orphans ()) []
+
+let compile to_client to_server =
+  let close_client close = function
+    | Close -> close lor 0b1100
+    | Shutdown `read -> close lor 0b1000
+    | Shutdown `write -> close lor 0b0100
+    | _ -> close
+  in
+  let close_server close = function
+    | Close -> close lor 0b0011
+    | Shutdown `read -> close lor 0b0010
+    | Shutdown `write -> close lor 0b0001
+    | _ -> close
+  in
+  let client = Buffer.create 0x100 in
+  let server = Buffer.create 0x100 in
+  let rec go close to_client to_server =
+    match (close, to_client, to_server) with
+    | _, [], _ | _, _, [] -> ()
+    | close, ((Shutdown _ | Close) as operation) :: to_client, _ ->
+        go (close_client close operation) to_client to_server
+    | close, _, ((Shutdown _ | Close) as operation) :: to_server ->
+        go (close_server close operation) to_client to_server
+    | close, Noop :: to_client, to_server | close, to_client, Noop :: to_server
+      ->
+        go close to_client to_server
+    | close, Send str :: to_client, Recv n :: to_server ->
+        assert (String.length str = n);
+        if close land 0b0100 = 0 && close land 0b0010 = 0 then
+          Buffer.add_string server str;
+        if close land 0b0100 = 0 && close land 0b0010 = 0 then
+          go close to_client to_server
+    | close, Recv n :: to_client, Send str :: to_server ->
+        assert (String.length str = n);
+        if close land 0b1000 = 0 && close land 0b0001 = 0 then
+          Buffer.add_string client str;
+        if close land 0b1000 = 0 && close land 0b0001 = 0 then
+          go close to_client to_server
+    | _, Send _ :: _, Send _ :: _ | _, Recv _ :: _, Recv _ :: _ ->
+        assert false (* GADT? *)
+  in
+  go 0x0 to_client to_server;
+  (Buffer.contents client, Buffer.contents server)
+
+let pp_exn ppf exn = Fmt.string ppf (Printexc.to_string exn)
+let pp_str ppf str = Hxd_string.pp Hxd.default ppf str
+
+let run seed operations =
+  Miou_unix.run ~domains:1 @@ fun () ->
+  let rng = Mirage_crypto_rng_miou_unix.(initialize (module Pfortuna)) in
+  let fd, addr, path = bind_and_listen () in
+  let finally () = Unix.unlink path in
+  Fun.protect ~finally @@ fun () ->
+  let cert, pk, authenticator =
+    Rresult.R.failwith_error_msg (Ca.make fuzz_coop seed)
+  in
+  let cfg_server =
+    Result.get_ok (Tls.Config.server ~certificates:(`Single ([ cert ], pk)) ())
+  in
+  let cfg_client = Result.get_ok (Tls.Config.client ~authenticator ()) in
+  let to_client, to_server = List.split operations in
+  let stop = Stop.create () in
+  let prm0 = Miou.async @@ fun () -> run_server ~to_server ~stop fd cfg_server in
+  let prm1 =
+    Miou.async @@ fun () ->
+    let finally () = Stop.stop stop in
+    Fun.protect ~finally @@ fun () -> run_client ~to_client cfg_client addr
+  in
+  let send_to_client, send_to_server = compile to_client to_server in
+  match (Miou.await prm0, Miou.await prm1) with
+  | Ok [ Ok send_to_server' ], Ok send_to_client' ->
+      Crowbar.check (String.equal send_to_client send_to_client');
+      Crowbar.check (String.equal send_to_server send_to_server');
+      let n = String.length send_to_client in
+      let m = String.length send_to_server in
+      Mirage_crypto_rng_miou_unix.kill rng;
+      epr "[%a] %db %db transmitted\n%!" Fmt.(styled `Green string) "OK" n m
+  | a, b ->
+      Mirage_crypto_rng_miou_unix.kill rng;
+      Crowbar.failf "[%a] Unexpected result: %a & %a\n%!"
+        Fmt.(styled `Red string) "ERROR"
+        Fmt.(Dump.result ~error:pp_exn ~ok:Fmt.(Dump.list (Dump.result ~error:pp_exn ~ok:pp_str))) a
+        Fmt.(Dump.result ~error:pp_exn ~ok:pp_str) b
+
+let label name gen = Crowbar.with_printer Fmt.(const string name) gen
+
+let direction =
+  let open Crowbar in
+  choose
+    [
+      label "server-to-client" (const `To_client);
+      label "client-to-server" (const `To_server);
+    ]
+
+let shutdown =
+  let open Crowbar in
+  choose
+    [
+      label "close" (const Close);
+      label "shutdown-recv" (const (Shutdown `read));
+      label "shutdown-send" (const (Shutdown `write));
+      label "noop" (const Noop);
+    ]
+
+let operation =
+  let open Crowbar in
+  map [ direction; bytes ] @@ fun direction str ->
+  match (direction, str) with
+  | _, "" -> (Noop, Noop)
+  | `To_server, str -> (Send str, Recv (String.length str))
+  | `To_client, str -> (Recv (String.length str), Send str)
+
+let counter = Atomic.make 0
+
+let operations =
+  let open Crowbar in
+  fix @@ fun m ->
+  let continue (to_client, to_server) =
+    if Atomic.fetch_and_add counter 1 >= 4 then const [ (Close, Close) ]
+    else map [ m ] @@ fun ops -> (to_client, to_server) :: ops
+  in
+  map
+    [ list1 operation; dynamic_bind (pair shutdown shutdown) continue ]
+    List.rev_append
+
+let seed = Crowbar.(map [ bytes ] Base64.encode_exn)
+
+let () =
+  Sys.set_signal Sys.sigpipe Sys.Signal_ignore;
+  Crowbar.add_test ~name:"run" Crowbar.[ seed; operations ] @@ fun seed operations ->
+  run seed operations;
+  Atomic.set counter 0