fix: limit mqtt max_packet_size to 256MB

apps/emqx/src/emqx_schema.erl

@@ -30,6 +30,7 @@
 -include_lib("hocon/include/hoconsc.hrl").
 -include_lib("logger.hrl").
 
+-define(MAX_INT_MQTT_PACKET_SIZE, 268435456).
 -define(MAX_INT_TIMEOUT_MS, 4294967295).
 %% floor(?MAX_INT_TIMEOUT_MS / 1000).
 -define(MAX_INT_TIMEOUT_S, 4294967).
@@ -45,6 +46,7 @@
 -type timeout_duration_s() :: 0..?MAX_INT_TIMEOUT_S.
 -type timeout_duration_ms() :: 0..?MAX_INT_TIMEOUT_MS.
 -type bytesize() :: integer().
+-type mqtt_max_packet_size() :: 1..?MAX_INT_MQTT_PACKET_SIZE.
 -type wordsize() :: bytesize().
 -type percent() :: float().
 -type file() :: string().
@@ -71,6 +73,7 @@
 -typerefl_from_string({timeout_duration_s/0, emqx_schema, to_timeout_duration_s}).
 -typerefl_from_string({timeout_duration_ms/0, emqx_schema, to_timeout_duration_ms}).
 -typerefl_from_string({bytesize/0, emqx_schema, to_bytesize}).
+-typerefl_from_string({mqtt_max_packet_size/0, emqx_schema, to_bytesize}).
 -typerefl_from_string({wordsize/0, emqx_schema, to_wordsize}).
 -typerefl_from_string({percent/0, emqx_schema, to_percent}).
 -typerefl_from_string({comma_separated_list/0, emqx_schema, to_comma_separated_list}).
@@ -151,6 +154,7 @@
     timeout_duration_s/0,
     timeout_duration_ms/0,
     bytesize/0,
+    mqtt_max_packet_size/0,
     wordsize/0,
     percent/0,
     file/0,
@@ -3357,7 +3361,7 @@ mqtt_general() ->
             )},
         {"max_packet_size",
             sc(
-                bytesize(),
+                mqtt_max_packet_size(),
                 #{
                     default => <<"1MB">>,
                     desc => ?DESC(mqtt_max_packet_size)

apps/emqx_dashboard/src/emqx_dashboard_swagger.erl

@@ -852,6 +852,8 @@ typename_to_spec("timeout()", _Mod) ->
     };
 typename_to_spec("bytesize()", _Mod) ->
     #{type => string, example => <<"32MB">>};
+typename_to_spec("mqtt_max_packet_size()", _Mod) ->
+    #{type => string, example => <<"32MB">>};
 typename_to_spec("wordsize()", _Mod) ->
     #{type => string, example => <<"1024KB">>};
 typename_to_spec("map()", _Mod) ->

changes/ce/fix-11184.en.md

@@ -0,0 +1 @@
+Config value for `max_packet_size` has a max value of 256MB defined by protocol. This is now enforced and any configuration with a value greater than that will break.