fix: read request body correctly

Author: savonarola

rebar.config

@@ -5,6 +5,14 @@
     {cowboy_swagger, {git, "https://github.com/emqx/cowboy_swagger", {tag, "2.7.0-emqx2"}}}
 ]}.
 
+{profiles, [
+    {test, [
+        {deps, [
+            {hackney, {git, "https://github.com/emqx/hackney.git", {tag, "1.18.1-1"}}}
+        ]}
+    ]}
+]}.
+
 {plugins, [
     {erlfmt, "1.6.0"}
 ]}.

src/minirest_body.erl

@@ -58,7 +58,7 @@ decoder(Request) ->
     end.
 
 json_decoder(Request) ->
-    {ok, Body, NRequest} = cowboy_req:read_body(Request),
+    {ok, Body, NRequest} = binary_decoder(Request),
     try
         {ok, jsx:decode(Body, [return_maps]), NRequest}
     catch
@@ -107,12 +107,12 @@ read_body(Request, Acc) ->
     end.
 
 binary_decoder(Request) ->
-    binary_decoder(Request, <<>>).
+    binary_decoder(Request, []).
 
 binary_decoder(Request, Acc) ->
     case cowboy_req:read_body(Request) of
-        {more, Bin, NewRequest} -> binary_decoder(NewRequest, <<Acc/binary, Bin/binary>>);
-        {ok, Bin, DoneRequest} -> {ok, <<Acc/binary, Bin/binary>>, DoneRequest}
+        {more, Bin, NewRequest} -> binary_decoder(NewRequest, [Bin | Acc]);
+        {ok, Bin, DoneRequest} -> {ok, iolist_to_binary(lists:reverse([Bin | Acc])), DoneRequest}
     end.
 
 %%==============================================================================================

test/minirest_handler_SUITE.erl

@@ -31,11 +31,13 @@ all() ->
         t_qs_params,
         t_auth_meta_in_filter,
         t_auth_meta_in_handler,
-        t_handler_meta_in_auth
+        t_handler_meta_in_auth,
+        t_post_large_body
     ].
 
 init_per_suite(Config) ->
     application:ensure_all_started(minirest),
+    application:ensure_all_started(hackney),
     Config.
 
 end_per_suite(_Config) ->
@@ -105,6 +107,15 @@ t_handler_meta_in_auth(_Config) ->
         httpc:request(address() ++ "/handler_meta_in_auth")
     ).
 
+t_post_large_body(_Config) ->
+    Data100KB = iolist_to_binary([$s || _ <- lists:seq(1, 100_000)]),
+    Data100MB = [Data100KB || _ <- lists:seq(1, 1000)],
+    Json100MB = jsx:encode(Data100MB),
+    URL = address() ++ "/post_large_body",
+    Headers = [{<<"content-type">>, <<"application/json">>}],
+    {ok, 200, _, Ref} = hackney:request(post, URL, Headers, Json100MB, []),
+    ?assertEqual({ok, <<"OK">>}, hackney:body(Ref)).
+
 %%--------------------------------------------------------------------
 %% Helpers
 %%--------------------------------------------------------------------

test/minirest_test_handler.erl

@@ -28,7 +28,8 @@
     qs_params/2,
     auth_meta_in_filter/2,
     auth_meta_in_handler/2,
-    handler_meta_in_auth/2
+    handler_meta_in_auth/2,
+    post_large_body/2
 ]).
 
 api_spec() ->
@@ -40,7 +41,8 @@ api_spec() ->
             qs_params(),
             auth_meta_in_filter(),
             auth_meta_in_handler(),
-            handler_meta_in_auth()
+            handler_meta_in_auth(),
+            post_large_body()
         ],
         []
     }.
@@ -124,6 +126,20 @@ handler_meta_in_auth() ->
     },
     {"/handler_meta_in_auth", MetaData, handler_meta_in_auth}.
 
+post_large_body() ->
+    MetaData = #{
+        post => #{
+            description => "post large body",
+            responses => text_plain_200_response(),
+            security => [#{application => []}]
+        }
+    },
+    {"/post_large_body", MetaData, post_large_body}.
+
+%%--------------------------------------------------------------------
+%% Handlers
+%%--------------------------------------------------------------------
+
 authorize1(_Req) ->
     {ok, #{message => <<"hello from authorize">>}}.
 
@@ -157,6 +173,9 @@ auth_meta_in_handler(get, #{auth_meta := #{message := Message}}) ->
 handler_meta_in_auth(get, #{auth_meta := #{message := Message}}) ->
     {200, #{<<"content-type">> => <<"test/plain">>}, Message}.
 
+post_large_body(post, #{body := _Body}) ->
+    {200, #{<<"content-type">> => <<"test/plain">>}, <<"OK">>}.
+
 %%--------------------------------------------------------------------
 %% Helpers
 %%--------------------------------------------------------------------