Ocsigen_response: Add 'response_string' and 'response_error'

This adds functions from `Cohttp_lwt_unix.Server` that are no longer
available with cohttp-eio.

Author: Julow

src/server/ocsigen_cohttp.ml

@@ -104,10 +104,9 @@ let handler ~ssl ~address ~port ~connector (flow, conn) request body =
       | `Not_found -> "Not Found"
       | _ -> Printexc.to_string exn
     in
-    Cohttp_lwt_unix.Server.respond_error ?headers
+    Ocsigen_response.respond_error ?headers
       ~status:(ret_code :> Cohttp.Code.status_code)
       ~body ()
-    >>= fun resp -> Lwt.return (Ocsigen_response.of_cohttp resp)
   in
   (* TODO: equivalent of Ocsigen_range *)
   let request =
@@ -137,8 +136,9 @@ let handler ~ssl ~address ~port ~connector (flow, conn) request body =
                  fun_request request |> Uri.to_string
                  |> Cohttp.Header.init_with "location"
                and status = `Moved_permanently in
-               Lwt.return (Ocsigen_response.respond ~headers ~status ())
-           | exn -> handle_error exn)
+               Lwt.return
+                 (Ocsigen_response.respond_string ~headers ~status ~body:"" ())
+           | exn -> Lwt.return (handle_error exn))
        >>= fun response ->
        Lwt.return (Ocsigen_response.to_response_expert response))
     (fun () ->

src/server/ocsigen_response.ml

@@ -38,6 +38,15 @@ let respond ?headers ~status ?(body = Body.empty) () =
   let response = Cohttp.Response.make ~status ~encoding ?headers () in
   make ~body response
 
+let respond_string ?headers ~status ~body () =
+  let encoding = Transfer.Fixed (Int64.of_int (String.length body)) in
+  let response = Response.make ~status ~encoding ?headers () in
+  let body = Body.of_string body in
+  make ~body response
+
+let respond_error ?headers ?(status = `Internal_server_error) ~body () =
+  respond_string ?headers ~status ~body:("Error: " ^ body) ()
+
 let update ?response ?body ?cookies {a_response; a_body; a_cookies} =
   let a_response =
     match response with Some response -> response | None -> a_response

src/server/ocsigen_response.mli

@@ -33,6 +33,25 @@ val respond :
 (** Like [make] but with an interface similar to
     [Cohttp_lwt_unix.Server.respond]. *)
 
+val respond_string :
+   ?headers:Cohttp.Header.t
+  -> status:Http.Status.t
+  -> body:string
+  -> unit
+  -> t
+(** Like [respond] but with a fixed string body. *)
+
+val respond_error :
+   ?headers:Cohttp.Header.t
+  -> ?status:Http.Status.t
+  -> body:string
+  -> unit
+  -> t
+(** Like [respond_string] with ["Error: "] appended to the body. The default
+    status is [`Internal_server_error].
+
+    @deprecated Use [respond_string] with a [~status] argument instead. *)
+
 val update :
    ?response:Cohttp.Response.t
   -> ?body:Body.t