From d25258943b66ae68c9d3fc05d5f26093046f0e6a Mon Sep 17 00:00:00 2001
From: k32 <10274441+k32@users.noreply.github.com>
Date: Wed, 12 Jan 2022 16:19:46 +0100
Subject: [PATCH] feat(bpapi): Verify emqx cluster RPC

---
 apps/emqx/src/bpapi/emqx_bpapi_static_checks.erl | 4 +++-
 apps/emqx/src/bpapi/emqx_bpapi_trans.erl         | 5 +++++
 apps/emqx_conf/src/emqx_cluster_rpc.erl          | 4 ++++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/apps/emqx/src/bpapi/emqx_bpapi_static_checks.erl b/apps/emqx/src/bpapi/emqx_bpapi_static_checks.erl
index b24b6747f..4d742c600 100644
--- a/apps/emqx/src/bpapi/emqx_bpapi_static_checks.erl
+++ b/apps/emqx/src/bpapi/emqx_bpapi_static_checks.erl
@@ -48,6 +48,8 @@
 -define(IGNORED_MODULES, "emqx_rpc").
 %% List of known RPC backend modules:
 -define(RPC_MODULES, "gen_rpc, erpc, rpc, emqx_rpc").
+%% List of known functions also known to do RPC:
+-define(RPC_FUNCTIONS, "emqx_cluster_rpc:multicall/3, emqx_cluster_rpc:multicall/5").
 %% List of functions in the RPC backend modules that we can ignore:
 -define(IGNORED_RPC_CALLS, "gen_rpc:nodes/0").
 
@@ -206,7 +208,7 @@ prepare(#{reldir := RelDir, plt := PLT}) ->
 
 find_remote_calls(_Opts) ->
     Query = "XC | (A - [" ?IGNORED_APPS "]:App - [" ?IGNORED_MODULES "] : Mod)
-               || ([" ?RPC_MODULES "] : Mod - " ?IGNORED_RPC_CALLS ")",
+               || (([" ?RPC_MODULES "] : Mod + [" ?RPC_FUNCTIONS "]) - " ?IGNORED_RPC_CALLS ")",
     {ok, Calls} = xref:q(?XREF, Query),
     ?INFO("Calls to RPC modules ~p", [Calls]),
     {Callers, _Callees} = lists:unzip(Calls),
diff --git a/apps/emqx/src/bpapi/emqx_bpapi_trans.erl b/apps/emqx/src/bpapi/emqx_bpapi_trans.erl
index eedaacd69..aec4aa320 100644
--- a/apps/emqx/src/bpapi/emqx_bpapi_trans.erl
+++ b/apps/emqx/src/bpapi/emqx_bpapi_trans.erl
@@ -158,6 +158,11 @@ extract_mfa(?BACKEND(RPC, CallOrCast), [_Node, M, F, A]) when ?IS_RPC(RPC) ->
     {call_or_cast(CallOrCast), M, F, A};
 extract_mfa(?BACKEND(RPC, CallOrCast), [_Node, M, F, A, _Timeout]) when ?IS_RPC(RPC) ->
     {call_or_cast(CallOrCast), M, F, A};
+%% emqx_cluster_rpc:
+extract_mfa(?BACKEND(emqx_cluster_rpc, multicall), [M, F, A]) ->
+    {call, M, F, A};
+extract_mfa(?BACKEND(emqx_cluster_rpc, multicall), [M, F, A, _RequiredNum, _Timeout]) ->
+    {call, M, F, A};
 extract_mfa(_, _) ->
     error("unrecognized RPC call").
 
diff --git a/apps/emqx_conf/src/emqx_cluster_rpc.erl b/apps/emqx_conf/src/emqx_cluster_rpc.erl
index 87758680f..58042e34e 100644
--- a/apps/emqx_conf/src/emqx_cluster_rpc.erl
+++ b/apps/emqx_conf/src/emqx_cluster_rpc.erl
@@ -18,6 +18,10 @@
 
 %% API
 -export([start_link/0, mnesia/1]).
+
+%% Note: multicall functions are statically checked by
+%% `emqx_bapi_trans' and `emqx_bpapi_static_checks' modules. Don't
+%% forget to update it when adding or removing them here:
 -export([multicall/3, multicall/5, query/1, reset/0, status/0,
          skip_failed_commit/1, fast_forward_to_commit/2]).
 -export([get_node_tnx_id/1, latest_tnx_id/0]).