`inets/httpd#c:do/1` nobody throws 500 internal server error.

[Green0wl]

Describe the bug

otp/lib/inets/src/http_server/httpd.erl

Line 874 in a4d5b23

Body :: iolist() | nobody | {Fun, FunArg},

says, nobody atom is a possible value for Body. Despite this fact, an 500 Internal Server Error occurs and body consists of fallback HTML.

To Reproduce

-module(my_mod).
-export([do/1]).

do(_) ->
    {break, [{response, {401, nobody}}]}.

-module(a).

-behaviour(application).

-export([start/2, stop/1]).

start(_, _) ->
    inets:start(),
    {ok, Pid} =
        inets:start(
            httpd,
            [
                {port, 8080},
                {server_root, "."},
                {document_root, "."},
                {bind_address, "localhost"},
                {modules, [
                    mod_alias,
                    mod_auth,
                    my_mod,
                    mod_esi,
                    mod_actions,
                    mod_cgi,
                    mod_get,
                    mod_head,
                    mod_log,
                    mod_disk_log
                ]}
            ]
        ),
    {ok, Pid}.

stop(Server) ->
    ok = inets:stop(httpd, Server).

And start with:

erlc a.erl my_mod.erl && erl -noinput -eval 'a:start(0, 0).'

Expected behavior
A response with status code 401 and empty body is sent back.

Affected versions
Erlang/OTP 28 [erts-16.1.1].

Additional context
No additional context.

[MarkoMin]

Looking at the source code, this was the old way of returning status code and body and it says that this way is deprecated and the new way should be used. Probably it doesn't handle nobody as it should.

Snippet from httpd_response.erl:

    case proplists:get_value(response, Data) of
	{already_sent, _StatusCode, _Size} ->
	    ok;
	{response, Header, Body} -> %% New way
	    send_response(ModData, Header, Body),
	    ok;
	{StatusCode, Response} ->   %% Old way
	    send_response_old(ModData, StatusCode, Response),
	    ok;
	undefined -> 
            ...
    end

Try with {break, [{response, {response, [{code, 401}], nobody}}]}, that should work.

Docs/specs are old.

[Green0wl]

@MarkoMin, you're right! it works now:

-module(my_mod).
-export([do/1]).

do(_) ->
    {break, [{response, {response, [{code, 401}], nobody}}]}.
    % {break, [{response, {401, nobody}}]}.

Thank you!

[Whaileee]

Hi. Thank you for reporting the issue. I'll update the docs to make this clearer to the reader.

Best regards,
Konrad