h2-lwt-unix: replace dune file written in OCaml with select form (#68)

Also remove `{build}` constraint from the dune dependency in opam files

CHANGES.md

@@ -1,6 +1,9 @@
 Unreleased
 --------------
 
+- h2-lwt-unix: replace the `dune` file (previously written in OCaml) with a
+  `(select)` form to avoid depending on `ocamlfind`
+  ([#68](https://github.com/anmonteiro/ocaml-h2/pull/68))
 - h2-lwt, h2-lwt-unix, h2-mirage: Refactor interface code through common
   `H2_lwt_intf` and expose less (internal) types
   ([#65](https://github.com/anmonteiro/ocaml-h2/pull/65))

h2-lwt-unix.opam

@@ -13,8 +13,7 @@ depends: [
   "ocaml" {>= "4.04"}
   "faraday-lwt-unix"
   "h2-lwt" {>= "0.2.0"}
-  "dune" {build}
-  "ocamlfind" {build}
+  "dune"
   "lwt"
 ]
 depopts: ["tls" "lwt_ssl"]

h2-lwt.opam

@@ -12,7 +12,7 @@ build: [
 depends: [
   "ocaml" {>= "4.04"}
   "h2" {>= "0.2.0"}
-  "dune" {build}
+  "dune"
   "lwt"
 ]
 synopsis: "Lwt support for h2"

h2-mirage.opam

@@ -13,7 +13,7 @@ depends: [
   "ocaml" {>= "4.04"}
   "faraday-lwt"
   "h2-lwt" {>= "0.2.0"}
-  "dune" {build}
+  "dune"
   "lwt"
   "mirage-conduit"
   "cstruct"

h2.opam

@@ -11,7 +11,7 @@ build: [
 ]
 depends: [
   "ocaml" {>= "4.04"}
-  "dune" {build}
+  "dune"
   "alcotest" {with-test}
   "yojson" {with-test}
   "hex" {with-test}

hpack.opam

@@ -9,7 +9,7 @@ dev-repo: "git+https://github.com/anmonteiro/ocaml-h2.git"
 doc: "https://anmonteiro.github.io/ocaml-h2/"
 depends: [
   "ocaml" {>= "4.04"}
-  "dune" {build}
+  "dune"
   "yojson" {with-test}
   "hex" {with-test}
   "angstrom"

lib/parse.ml

@@ -573,13 +573,25 @@ module Reader = struct
 
   let client_frames preface_handler frame_handler =
     connection_preface_and_frames
+      (* From RFC7540§3.5:
+       *   The server connection preface consists of a potentially empty
+       *   SETTINGS frame (Section 6.5) that MUST be the first frame the server
+       *   sends in the HTTP/2 connection. *)
       settings_preface
       preface_handler
       frame_handler
 
   let server_frames preface_handler frame_handler =
     connection_preface_and_frames
       (fun parse_context ->
+        (* From RFC7540§3.5:
+         *   The client connection preface starts with a sequence of 24 octets,
+         *   which in hex notation is:
+         *
+         *     0x505249202a20485454502f322e300d0a0d0a534d0d0a0d0a
+         *   That is, the connection preface starts with the string
+         *   PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n). This sequence MUST be followed
+         *   by a SETTINGS frame (Section 6.5), which MAY be empty. *)
         connection_preface *> settings_preface parse_context)
       preface_handler
       frame_handler

lwt-unix/dune

@@ -1,36 +1,21 @@
-(* -*- tuareg -*- *)
-(* This was inspired by `conduit-lwt-unix`'s dune file *)
-
-let v ~ssl ~tls () =
-  let ssl, ssl_d =
-    if ssl then "ssl_io_real", "lwt_ssl "
-    else "ssl_io_dummy", ""
-  in
-  let tls, tls_d =
-    if tls then "tls_io_real", "tls.lwt "
-    else "tls_io_dummy", ""
-  in
-  Printf.sprintf {|
-(rule (copy %s.ml ssl_io.ml))
-(rule (copy %s.ml tls_io.ml))
-
 (library
  (name h2_lwt_unix)
  (public_name h2-lwt-unix)
- (libraries faraday-lwt-unix h2 h2-lwt lwt.unix %s%s)
+ (libraries
+  faraday-lwt-unix
+  h2
+  h2-lwt
+  lwt.unix
+  (select
+   ssl_io.ml
+   from
+   (lwt_ssl -> ssl_io_real.ml)
+   (-> ssl_io_dummy.ml))
+  (select
+   tls_io.ml
+   from
+   (tls.lwt -> tls_io_real.ml)
+   (-> tls_io_dummy.ml)))
  (modules h2_lwt_unix tls_io ssl_io)
- (flags (:standard -safe-string)))
-|} ssl tls ssl_d tls_d
-
-let main () =
-  let is_installed s = Printf.kprintf Sys.command "ocamlfind query %s" s = 0 in
-  let ssl = is_installed "lwt_ssl" in
-  let tls = is_installed "tls.lwt" in
-  Printf.printf
-    "Configuration\n\
-    \  ssl    : %b\n\
-    \  tls    : %b\n%!"
-    ssl tls;
-  v ~ssl ~tls ()
-
-let () = Jbuild_plugin.V1.send @@ main ()
+ (flags
+  (:standard -safe-string)))