In content-types, the charset parameter is converted to lowercase

We know this specific parameter is case insensitive so we
automatically lowercase it to make things simpler to the
developer.

manual/cowboy_req.md

@@ -176,7 +176,7 @@ Request related exports
 > | accept-language        | `[{LanguageTag, Quality}]`                        |
 > | authorization          | `{AuthType, Credentials}`                         |
 > | content-length         | `non_neg_integer()`                               |
-> | content-type           | `{Type, SubType, Params}`                         |
+> | content-type           | `{Type, SubType, ContentTypeParams}`              |
 > | cookie                 | `[{binary(), binary()}]`                          |
 > | expect                 | `[Expect | {Expect, ExpectValue, Params}]`        |
 > | if-match               | `'*' | [{weak | strong, OpaqueTag}]`              |
@@ -192,7 +192,7 @@ Request related exports
 > Types for the above table:
 >  *  Type = SubType = Charset = Encoding = LanguageTag = binary()
 >  *  AuthType = Expect = OpaqueTag = Unit = binary()
->  *  Params = [{binary(), binary()}]
+>  *  Params = ContentTypeParams = [{binary(), binary()}]
 >  *  Quality = 0..1000
 >  *  AcceptExt = [{binary(), binary()} | binary()]
 >  *  Credentials - see below
@@ -201,8 +201,9 @@ Request related exports
 > The cookie names and values, the values of the sec-websocket-protocol
 > and x-forwarded-for headers, the values in `AcceptExt` and `Params`,
 > the authorization `Credentials`, the `ExpectValue` and `OpaqueTag`
-> are case sensitive. All other values are case insensitive and
-> will be returned as lowercase.
+> are case sensitive. All values in `ContentTypeParams` are case sensitive
+> except the value of the charset parameter, which is case insensitive.
+> All other values are case insensitive and will be returned as lowercase.
 >
 > The headers accept, accept-encoding and cookie headers can return
 > an empty list. Others will return `{error, badarg}` if the header

manual/cowboy_rest.md

@@ -168,7 +168,9 @@ REST callbacks description
 > Cowboy will select the most appropriate content-type from the list.
 > If any parameter is acceptable, then the tuple form should be used
 > with parameters set to `'*'`. If the parameters value is set to `[]`
-> only content-type values with no parameters will be accepted.
+> only content-type values with no parameters will be accepted. All
+> parameter values are treated in a case sensitive manner except the
+> `charset` parameter, if present, which is case insensitive.
 >
 > This function will be called for POST, PUT and PATCH requests.
 > It is entirely possible to define different callbacks for different
@@ -219,7 +221,9 @@ REST callbacks description
 > Cowboy will select the most appropriate content-type from the list.
 > If any parameter is acceptable, then the tuple form should be used
 > with parameters set to `'*'`. If the parameters value is set to `[]`
-> only content-type values with no parameters will be accepted.
+> only content-type values with no parameters will be accepted. All
+> parameter values are treated in a case sensitive manner except the
+> `charset` parameter, if present, which is case insensitive.
 >
 > The `ProvideResource` value is the name of the callback that will
 > be called if the content-type matches. It is defined as follow.

src/cowboy_http.erl

@@ -162,14 +162,26 @@ cookie_value(<< C, Rest/binary >>, Fun, Acc) ->
 	cookie_value(Rest, Fun, << Acc/binary, C >>).
 
 %% @doc Parse a content type.
+%%
+%% We lowercase the charset header as we know it's case insensitive.
 -spec content_type(binary()) -> any().
 content_type(Data) ->
 	media_type(Data,
 		fun (Rest, Type, SubType) ->
-				params(Rest,
-					fun (<<>>, Params) -> {Type, SubType, Params};
-						(_Rest2, _) -> {error, badarg}
-					end)
+			params(Rest,
+				fun (<<>>, Params) ->
+						case lists:keyfind(<<"charset">>, 1, Params) of
+							false ->
+								{Type, SubType, Params};
+							{_, Charset} ->
+								Charset2 = cowboy_bstr:to_lower(Charset),
+								Params2 = lists:keyreplace(<<"charset">>,
+									1, Params, {<<"charset">>, Charset2}),
+								{Type, SubType, Params2}
+						end;
+					(_Rest2, _) ->
+						{error, badarg}
+				end)
 		end).
 
 %% @doc Parse a media range.

test/http_SUITE.erl

@@ -64,6 +64,7 @@
 -export([rest_options_default/1]).
 -export([rest_param_all/1]).
 -export([rest_patch/1]).
+-export([rest_post_charset/1]).
 -export([rest_postonly/1]).
 -export([rest_resource_etags/1]).
 -export([rest_resource_etags_if_none_match/1]).
@@ -138,6 +139,7 @@ groups() ->
 		rest_options_default,
 		rest_param_all,
 		rest_patch,
+		rest_post_charset,
 		rest_postonly,
 		rest_resource_etags,
 		rest_resource_etags_if_none_match,
@@ -370,6 +372,7 @@ init_dispatch(Config) ->
 			{"/missing_get_callbacks", rest_missing_callbacks, []},
 			{"/missing_put_callbacks", rest_missing_callbacks, []},
 			{"/nodelete", rest_nodelete_resource, []},
+			{"/post_charset", rest_post_charset_resource, []},
 			{"/postonly", rest_postonly_resource, []},
 			{"/patch", rest_patch_resource, []},
 			{"/resetags", rest_resource_etags, []},
@@ -999,6 +1002,15 @@ rest_patch(Config) ->
 		ok
 	end || {Status, Headers, Body} <- Tests].
 
+rest_post_charset(Config) ->
+	Client = ?config(client, Config),
+	Headers = [
+		{<<"content-type">>, <<"text/plain;charset=UTF-8">>}
+	],
+	{ok, Client2} = cowboy_client:request(<<"POST">>,
+		build_url("/post_charset", Config), Headers, "12345", Client),
+	{ok, 204, _, _} = cowboy_client:response(Client2).
+
 rest_postonly(Config) ->
 	Client = ?config(client, Config),
 	Headers = [

test/http_SUITE_data/rest_post_charset_resource.erl

@@ -0,0 +1,15 @@
+-module(rest_post_charset_resource).
+-export([init/3, allowed_methods/2, content_types_accepted/2, from_text/2]).
+
+init(_Transport, _Req, _Opts) ->
+	{upgrade, protocol, cowboy_rest}.
+
+allowed_methods(Req, State) ->
+	{[<<"POST">>], Req, State}.
+
+content_types_accepted(Req, State) ->
+	{[{{<<"text">>, <<"plain">>, [{<<"charset">>, <<"utf-8">>}]},
+		from_text}], Req, State}.
+
+from_text(Req, State) ->
+	{true, Req, State}.