anil.recoil.org
A batteries included HTTP/1.1 client in OCaml
Store HTTP headers in lowercase for HTTP/2 compatibility
HTTP/2 requires all header names to be lowercase (RFC 9113). Previously,
the library stored headers with canonical HTTP/1.x capitalization (e.g.,
"Accept-Encoding"), causing HTTP/2 requests to fail with "Header name
contains uppercase" errors.
Since HTTP/1.x headers are case-insensitive (RFC 9110), storing them in
lowercase is equally valid for both protocols. This change:
- Updates Headers.add and Headers.set to store lowercase names
- Removes uppercase validation from validate_h2_user_headers
- Removes redundant headers_to_h2/headers_of_h2 wrappers from h2_adapter
(now just uses Headers.to_list/of_list directly)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
+26
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+23
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lib/core/headers.ml
+23
-23
lib/core/headers.ml
···
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(** {1 Core Operations with Typed Header Names} *)
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let add (name : Header_name.t) value t =
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let canonical = Header_name.to_string name in
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let nkey = Header_name.to_lowercase_string name in
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+
(* Store header names in lowercase for HTTP/2 compatibility.
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HTTP/1.x headers are case-insensitive per RFC 9110. *)
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let canonical = Header_name.to_lowercase_string name in
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let nkey = canonical in
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validate_header_value canonical value;
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let existing =
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match StringMap.find_opt nkey t with
···
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StringMap.add nkey (canonical, existing @ [value]) t
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let set (name : Header_name.t) value t =
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let canonical = Header_name.to_string name in
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let nkey = Header_name.to_lowercase_string name in
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+
(* Store header names in lowercase for HTTP/2 compatibility.
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HTTP/1.x headers are case-insensitive per RFC 9110. *)
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let canonical = Header_name.to_lowercase_string name in
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let nkey = canonical in
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validate_header_value canonical value;
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StringMap.add nkey (canonical, [value]) t
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···
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(* Validate user-provided headers for HTTP/2 (before pseudo-headers are added).
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Per RFC 9113 Section 8.2.2 and 8.3, validates:
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- No pseudo-headers (user should not provide them)
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-
- No uppercase letters in header names
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- No connection-specific headers
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-
- TE header only contains "trailers" if present *)
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+
- TE header only contains "trailers" if present
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+
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Note: We don't reject uppercase header names here because the library
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internally stores headers with canonical HTTP/1.x names (e.g., "Accept-Encoding").
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The h2_adapter lowercases all header names before sending to HTTP/2. *)
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let headers_list = to_list t in
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(* Check for any pseudo-headers (user should not provide them) *)
···
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let name_without_colon = String.sub name 1 (String.length name - 1) in
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Error (Invalid_pseudo (name_without_colon ^ " (user-provided headers must not contain pseudo-headers)"))
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| None ->
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(* Check for uppercase in header names *)
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let uppercase_header = List.find_opt (fun (name, _) ->
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contains_uppercase name
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-
) headers_list in
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match uppercase_header with
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| Some (name, _) -> Error (Uppercase_header_name name)
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-
| None ->
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(* Check for forbidden connection-specific headers *)
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let has_forbidden = List.exists (fun h -> mem h t) h2_forbidden_headers in
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if has_forbidden then
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Error Connection_header_forbidden
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else
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(* Check TE header - only "trailers" is allowed *)
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match get `Te t with
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| Some te when String.lowercase_ascii (String.trim te) <> "trailers" ->
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Error Te_header_invalid
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-
| _ -> Ok ()
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(* Check for forbidden connection-specific headers *)
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let has_forbidden = List.exists (fun h -> mem h t) h2_forbidden_headers in
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if has_forbidden then
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Error Connection_header_forbidden
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else
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+
(* Check TE header - only "trailers" is allowed *)
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match get `Te t with
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| Some te when String.lowercase_ascii (String.trim te) <> "trailers" ->
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Error Te_header_invalid
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+
| _ -> Ok ()
+3
-12
lib/h2/h2_adapter.ml
+3
-12
lib/h2/h2_adapter.ml
···
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This module provides integration between the H2 implementation and
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the Requests library, handling:
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- Header type conversion (H2's string pairs to Headers.t)
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- Automatic response decompression
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- HTTP/2 connection state management for reuse *)
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···
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body : string;
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}
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(** {1 Header Conversion} *)
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-
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let headers_of_h2 (h2_headers : (string * string) list) : Headers.t =
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Headers.of_list h2_headers
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-
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let headers_to_h2 (headers : Headers.t) : (string * string) list =
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Headers.to_list headers
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-
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(** {1 Body Conversion} *)
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let body_to_string_opt (body : Body.t) : string option =
···
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(** Convert H2 protocol response to adapter response with decompression. *)
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let make_response ~auto_decompress (h2_resp : H2_protocol.response) =
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let headers = headers_of_h2 h2_resp.H2_protocol.headers in
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let headers = Headers.of_list h2_resp.H2_protocol.headers in
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let body = decompress_body ~auto_decompress ~headers h2_resp.H2_protocol.body in
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{ status = h2_resp.H2_protocol.status; headers; body }
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···
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| Ok () ->
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let host = Uri.host uri |> Option.value ~default:"" in
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let port = Uri.port uri |> Option.value ~default:443 in
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let h2_headers = headers_to_h2 headers in
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+
let h2_headers = Headers.to_list headers in
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let h2_body = Option.bind body body_to_string_opt in
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let client, needs_handshake = get_or_create_client ~host ~port in
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let handshake_result =
···
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Error (Format.asprintf "Invalid HTTP/2 request headers: %a"
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Headers.pp_h2_validation_error e)
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| Ok () ->
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let h2_headers = headers_to_h2 headers in
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+
let h2_headers = Headers.to_list headers in
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let h2_body = Option.bind body body_to_string_opt in
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let meth = Method.to_string method_ in
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H2_client.one_request flow ~meth ~uri ~headers:h2_headers ?body:h2_body ()
-9
lib/h2/h2_adapter.mli
-9
lib/h2/h2_adapter.mli
···
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8
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This module provides integration between the H2 implementation and
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9
the Requests library, handling:
10
-
- Header type conversion (H2's string pairs to {!Headers.t})
11
10
- Automatic response decompression
12
11
- HTTP/2 connection state management for reuse
13
12
···
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headers : Headers.t;
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body : string;
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}
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-
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(** {1 Header Conversion} *)
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-
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val headers_of_h2 : (string * string) list -> Headers.t
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(** [headers_of_h2 pairs] converts H2 header pairs to {!Headers.t}. *)
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-
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val headers_to_h2 : Headers.t -> (string * string) list
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(** [headers_to_h2 headers] converts {!Headers.t} to H2 header pairs. *)
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(** {1 Body Conversion} *)
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