fix(emqx_st_statistics): fix unsafe rank range (#6207)

* fix(emqx_st_statistics): fix unsafe rank range

apps/emqx_plugin_libs/src/emqx_st_statistics/emqx_st_statistics_api.erl

@@ -51,9 +51,23 @@ get_history(_Bindings, Params) ->
     Limit = erlang:binary_to_integer(LimitT),
     Start = (Page - 1) * Limit + 1,
     Size = ets:info(?TOPK_TAB, size),
-    EndT = Start + Limit - 1,
-    End = erlang:min(EndT, Size),
-    Infos = lists:foldl(fun(Rank, Acc) ->
+    End = Start + Limit - 1,
+    {HasNext, Count, Infos} = get_history(Start, End, Size),
+    return({ok, #{meta => #{page => Page,
+                            limit => Limit,
+                            hasnext => HasNext,
+                            count => Count},
+                  data => Infos}}).
+
+
+get_history(Start, _End, Size) when Start > Size ->
+    {false, 0, []};
+
+get_history(Start, End, Size) when End > Size ->
+    get_history(Start, Size, Size);
+
+get_history(Start, End, Size) ->
+    Fold = fun(Rank, Acc) ->
                    [#top_k{topic = Topic
                           , average_count = Count
                           , average_elapsed = Elapsed}] = ets:lookup(?TOPK_TAB, Rank),
@@ -65,11 +79,5 @@ get_history(_Bindings, Params) ->
 
                    [Info | Acc]
            end,
-                        [],
-                        lists:seq(Start, End)),
-
-    return({ok, #{meta => #{page => Page,
-                            limit => Limit,
-                            hasnext => End < Size,
-                            count => End - Start + 1},
-                  data => Infos}}).
+    Infos = lists:foldl(Fold, [], lists:seq(Start, End)),
+    {End < Size, End - Start + 1, Infos}.

lib-ce/emqx_modules/test/emqx_st_statistics_api_SUITE.erl

@@ -55,23 +55,6 @@ end_per_testcase(_, Config) ->
     emqx_mod_st_statistics:unload(undefined),
     Config.
 
-get(Key, ResponseBody) ->
-    maps:get(Key, jiffy:decode(list_to_binary(ResponseBody), [return_maps])).
-
-lookup_alarm(Name, [#{<<"name">> := Name} | _More]) ->
-    true;
-lookup_alarm(Name, [_Alarm | More]) ->
-    lookup_alarm(Name, More);
-lookup_alarm(_Name, []) ->
-    false.
-
-is_existing(Name, [#{name := Name} | _More]) ->
-    true;
-is_existing(Name, [_Alarm | More]) ->
-    is_existing(Name, More);
-is_existing(_Name, []) ->
-    false.
-
 t_get_history(_) ->
     ets:insert(?TOPK_TAB, #top_k{rank = 1,
                                  topic = <<"test">>,
@@ -81,7 +64,7 @@ t_get_history(_) ->
     {ok, Data} = request_api(get, api_path(["slow_topic"]), "_page=1&_limit=10",
                              auth_header_()),
 
-    Return = #{meta => #{page => 1,
+    ShouldRet = #{meta => #{page => 1,
                             limit => 10,
                             hasnext => false,
                             count => 1},
@@ -91,9 +74,44 @@ t_get_history(_) ->
                               count => 12}],
                    code => 0},
 
-    ShouldBe = emqx_json:encode(Return),
+    Ret = decode(Data),
 
-    ?assertEqual(ShouldBe, erlang:list_to_binary(Data)).
+    ?assertEqual(ShouldRet, Ret).
+
+t_rank_range(_) ->
+    Insert = fun(Rank) ->
+                     ets:insert(?TOPK_TAB,
+                                #top_k{rank = Rank,
+                                       topic = <<"test">>,
+                                       average_count = 12,
+                                       average_elapsed = 1500})
+             end,
+    lists:foreach(Insert, lists:seq(1, 15)),
+
+    timer:sleep(100),
+
+    {ok, Data} = request_api(get, api_path(["slow_topic"]), "_page=1&_limit=10",
+                             auth_header_()),
+
+    Meta1 = #{page => 1, limit => 10, hasnext => true, count => 10},
+    Ret1 = decode(Data),
+    ?assertEqual(Meta1, maps:get(meta, Ret1)),
+
+    %% End > Size
+    {ok, Data2} = request_api(get, api_path(["slow_topic"]), "_page=2&_limit=10",
+                              auth_header_()),
+
+    Meta2 = #{page => 2, limit => 10, hasnext => false, count => 5},
+    Ret2 = decode(Data2),
+    ?assertEqual(Meta2, maps:get(meta, Ret2)),
+
+    %% Start > Size
+    {ok, Data3} = request_api(get, api_path(["slow_topic"]), "_page=3&_limit=10",
+                              auth_header_()),
+
+    Meta3 = #{page => 3, limit => 10, hasnext => false, count => 0},
+    Ret3 = decode(Data3),
+    ?assertEqual(Meta3, maps:get(meta, Ret3)).
 
 t_clear(_) ->
     ets:insert(?TOPK_TAB, #top_k{rank = 1,
@@ -106,6 +124,25 @@ t_clear(_) ->
 
     ?assertEqual(0, ets:info(?TOPK_TAB, size)).
 
+decode(Data) ->
+    Pairs = emqx_json:decode(Data),
+    to_maps(Pairs).
+
+to_maps([H | _] = List) when is_tuple(H) ->
+    to_maps(List, #{});
+
+to_maps([_ | _] = List) ->
+    [to_maps(X) || X <- List];
+
+to_maps(V) -> V.
+
+to_maps([{K, V} | T], Map) ->
+    AtomKey = erlang:binary_to_atom(K),
+    to_maps(T, Map#{AtomKey => to_maps(V)});
+
+to_maps([], Map) ->
+    Map.
+
 request_api(Method, Url, Auth) ->
     request_api(Method, Url, [], Auth, []).
 
@@ -148,8 +185,3 @@ auth_header_(User, Pass) ->
 
 api_path(Parts)->
     ?HOST ++ filename:join([?BASE_PATH, ?API_VERSION] ++ Parts).
-
-filter(List, Key, Value) ->
-    lists:filter(fun(Item) ->
-        maps:get(Key, Item) == Value
-    end, List).