Add TE header in client. Check TE header in server

CHANGES.md

@@ -1,4 +1,5 @@
 ## Unreleased
+- cohttp-eio: add TE header in client. Check TE header is server (bikallem #941)
 - cohttp-eio: add User-Agent header to request from Client (bikallem #940)
 - cohttp-eio: add Content-Length header to request/response (bikallem #929)
 - cohttp-eio: add cohttp-eio client api - Cohttp_eio.Client (bikallem #879)

cohttp-eio/src/body.ml

@@ -218,7 +218,7 @@ let read_chunked reader headers f =
   | _ -> None
 
 (* https://datatracker.ietf.org/doc/html/rfc7230#section-4.1 *)
-let write_chunked writer chunk_writer =
+let write_chunked ?(write_chunked_trailers = false) writer chunk_writer =
   let write_extensions exts =
     List.iter
       (fun { name; value } ->
@@ -241,13 +241,15 @@ let write_chunked writer chunk_writer =
         Buf_write.string writer "\r\n"
   in
   chunk_writer.body_writer write_body;
-  chunk_writer.trailer_writer (Rwer.write_headers writer);
+  if write_chunked_trailers then
+    chunk_writer.trailer_writer (Rwer.write_headers writer);
   Buf_write.string writer "\r\n"
 
-let write_body writer body =
+let write_body ?write_chunked_trailers writer body =
   match body with
   | Fixed s -> Buf_write.string writer s
-  | Chunked chunk_writer -> write_chunked writer chunk_writer
+  | Chunked chunk_writer ->
+      write_chunked ?write_chunked_trailers writer chunk_writer
   | Custom f -> f writer
   | Empty -> ()
 

cohttp-eio/src/client.ml

@@ -25,7 +25,7 @@ type 'a body_allowed_call =
   response
 
 (* Request line https://datatracker.ietf.org/doc/html/rfc7230#section-3.1.1 *)
-let write_request writer request body =
+let write_request request writer body =
   let headers =
     Body.add_content_length
       (Http.Request.requires_content_length request)
@@ -42,7 +42,7 @@ let write_request writer request body =
   Buf_write.string writer "\r\n";
   Rwer.write_headers writer headers;
   Buf_write.string writer "\r\n";
-  Body.write_body writer body
+  Body.write_body ~write_chunked_trailers:true writer body
 
 (* response parser *)
 
@@ -85,12 +85,12 @@ let call ?meth ?version ?(headers = Http.Header.init ()) ?(body = Body.Empty)
   let headers =
     Http.Header.add_unless_exists headers "User-Agent" "cohttp-eio"
   in
-  let request = Http.Request.make ?meth ?version ~headers resource_path in
-  Buf_write.with_flow ~initial_size:0x1000 conn (fun writer ->
-      write_request writer request body;
-      let reader =
-        Eio.Buf_read.of_flow ~initial_size:0x1000 ~max_size:max_int conn
-      in
+  let initial_size = 0x1000 in
+  Buf_write.with_flow ~initial_size conn (fun writer ->
+      let request = Http.Request.make ?meth ?version ~headers resource_path in
+      let request = Http.Request.add_te_trailers request in
+      write_request request writer body;
+      let reader = Eio.Buf_read.of_flow ~initial_size ~max_size:max_int conn in
       let response = response reader in
       (response, reader))
 

cohttp-eio/src/rwer.ml

@@ -52,6 +52,7 @@ let http_headers r =
   Http.Header.of_list (aux ())
 
 let write_headers writer headers =
+  let headers = Http.Header.clean_dup headers in
   Http.Header.iter
     (fun k v ->
       Buf_write.string writer k;

cohttp-eio/src/server.ml

@@ -65,8 +65,9 @@ let internal_server_error_response =
 let bad_request_response =
   (Http.Response.make ~status:`Bad_request (), Body.Empty)
 
-let write_response writer ?request_meth (response, body) =
+let write_response ?request writer (response, body) =
   let headers =
+    let request_meth = Option.map Http.Request.meth request in
     Body.add_content_length
       (Http.Response.requires_content_length ?request_meth response)
       (Http.Response.headers response)
@@ -80,7 +81,10 @@ let write_response writer ?request_meth (response, body) =
   Buf_write.string writer "\r\n";
   Rwer.write_headers writer headers;
   Buf_write.string writer "\r\n";
-  Body.write_body writer body
+  let write_chunked_trailers =
+    Option.map Http.Request.supports_chunked_trailers request
+  in
+  Body.write_body ?write_chunked_trailers writer body
 
 (* request parsers *)
 
@@ -108,9 +112,7 @@ let rec handle_request client_addr reader writer flow handler =
   match http_request reader with
   | request ->
       let response, body = handler (request, reader, client_addr) in
-      write_response writer
-        ~request_meth:(Http.Request.meth request)
-        (response, body);
+      write_response ~request writer (response, body);
       if Http.Request.is_keep_alive request then
         handle_request client_addr reader writer flow handler
   | (exception End_of_file) | (exception Eio.Net.Connection_reset _) -> ()

cohttp-eio/tests/test_client.t

@@ -9,7 +9,7 @@ Test Client.get
   version: HTTP/1.1
   headers: Header {
    Accept = "application/json"; Host = "localhost:8082";
-   User-Agent = "cohttp-eio" }
+   User-Agent = "cohttp-eio"; TE = "trailers"; Connection = "TE" }
 
   $ kill ${running_pid}
 
@@ -24,7 +24,7 @@ Test Client.post
   version: HTTP/1.1
   headers: Header {
    Accept = "application/json"; Content-Length = "12"; Host = "localhost:8082";
-   User-Agent = "cohttp-eio" }
+   User-Agent = "cohttp-eio"; TE = "trailers"; Connection = "TE" }
 
   hello world!
 
@@ -42,7 +42,7 @@ Test posting "chunked" data
   headers: Header {
    Content-Length = "23"; Header1 = "Header1 value text";
    Content-Type = "text/plain"; Host = "localhost:8082";
-   User-Agent = "cohttp-eio" }
+   User-Agent = "cohttp-eio"; TE = "trailers"; Connection = "TE" }
 
   size: 7
    data: Mozilla

http/src/http.ml

@@ -769,6 +769,14 @@ module Request = struct
 
   let content_length t = content_length (requires_content_length t) t.headers
 
+  let supports_chunked_trailers t =
+    Header.get_multi t.headers "TE" |> List.mem "trailers"
+
+  let add_te_trailers t =
+    let headers = Header.add t.headers "TE" "trailers" in
+    let headers = Header.add headers "Connection" "TE" in
+    { t with headers }
+
   (* Defined for method types in RFC7231 *)
   let has_body req =
     match req.meth with

http/src/http.mli

@@ -410,6 +410,14 @@ module Request : sig
 
       See https://www.rfc-editor.org/rfc/rfc7230#section-3.3.2 *)
 
+  val supports_chunked_trailers : t -> bool
+  (** [supports_chunked_trailers t] is [true] if [t] contains HTTP header "TE:
+      trailers". Otherwise it is [false]. *)
+
+  val add_te_trailers : t -> t
+  (** [add_te_trailers t] adds HTTP headers, 'TE' and 'Connection' to
+      indicate that a user-agent can handle HTTP chunked trailers headers. *)
+
   val make :
     ?meth:Method.t ->
     ?version:Version.t ->