Fix crash on RM_Call inside module load (#11346)

PR #9320 introduces initialization order changes. Now cluster is initialized after modules.
This changes causes a crash if the module uses RM_Call inside the load function
on cluster mode (the code will try to access `server.cluster` which at this point is NULL).

To solve it, separate cluster initialization into 2 phases:
1. Structure initialization that happened before the modules initialization
2. Listener initialization that happened after.

Test was added to verify the fix.

src/cluster.c

@@ -694,27 +694,6 @@ void clusterInit(void) {
         exit(1);
     }
 
-    if (connectionIndexByType(connTypeOfCluster()->get_type(NULL)) < 0) {
-        serverLog(LL_WARNING, "Missing connection type %s, but it is required for the Cluster bus.", connTypeOfCluster()->get_type(NULL));
-        exit(1);
-    }
-
-    connListener *listener = &server.clistener;
-    listener->count = 0;
-    listener->bindaddr = server.bindaddr;
-    listener->bindaddr_count = server.bindaddr_count;
-    listener->port = server.cluster_port ? server.cluster_port : port + CLUSTER_PORT_INCR;
-    listener->ct = connTypeOfCluster();
-    if (connListen(listener) == C_ERR ) {
-        /* Note: the following log text is matched by the test suite. */
-        serverLog(LL_WARNING, "Failed listening on port %u (cluster), aborting.", listener->port);
-        exit(1);
-    }
-    
-    if (createSocketAcceptHandler(&server.clistener, clusterAcceptHandler) != C_OK) {
-        serverPanic("Unrecoverable error creating Redis Cluster socket accept handler.");
-    }
-
     /* Initialize data for the Slot to key API. */
     slotToKeyInit(server.db);
 
@@ -733,6 +712,30 @@ void clusterInit(void) {
     clusterUpdateMyselfHostname();
 }
 
+void clusterInitListeners(void) {
+    if (connectionIndexByType(connTypeOfCluster()->get_type(NULL)) < 0) {
+        serverLog(LL_WARNING, "Missing connection type %s, but it is required for the Cluster bus.", connTypeOfCluster()->get_type(NULL));
+        exit(1);
+    }
+
+    int port = server.tls_cluster ? server.tls_port : server.port;
+    connListener *listener = &server.clistener;
+    listener->count = 0;
+    listener->bindaddr = server.bindaddr;
+    listener->bindaddr_count = server.bindaddr_count;
+    listener->port = server.cluster_port ? server.cluster_port : port + CLUSTER_PORT_INCR;
+    listener->ct = connTypeOfCluster();
+    if (connListen(listener) == C_ERR ) {
+        /* Note: the following log text is matched by the test suite. */
+        serverLog(LL_WARNING, "Failed listening on port %u (cluster), aborting.", listener->port);
+        exit(1);
+    }
+    
+    if (createSocketAcceptHandler(&server.clistener, clusterAcceptHandler) != C_OK) {
+        serverPanic("Unrecoverable error creating Redis Cluster socket accept handler.");
+    }
+}
+
 /* Reset a node performing a soft or hard reset:
  *
  * 1) All other nodes are forgotten.

src/cluster.h

@@ -383,6 +383,7 @@ static_assert(offsetof(clusterMsg, data) == 2256, "unexpected field offset");
 
 /* ---------------------- API exported outside cluster.c -------------------- */
 void clusterInit(void);
+void clusterInitListeners(void);
 void clusterCron(void);
 void clusterBeforeSleep(void);
 clusterNode *getNodeByQuery(client *c, struct redisCommand *cmd, robj **argv, int argc, int *hashslot, int *ask);

src/server.c

@@ -7053,6 +7053,9 @@ int main(int argc, char **argv) {
     if (server.set_proc_title) redisSetProcTitle(NULL);
     redisAsciiArt();
     checkTcpBacklogSettings();
+    if (server.cluster_enabled) {
+        clusterInit();
+    }
     if (!server.sentinel_mode) {
         moduleInitModulesSystemLast();
         moduleLoadFromQueue();
@@ -7060,7 +7063,7 @@ int main(int argc, char **argv) {
     ACLLoadUsersAtStartup();
     initListeners();
     if (server.cluster_enabled) {
-        clusterInit();
+        clusterInitListeners();
     }
     InitServerLast();
 

tests/modules/basics.c

@@ -893,6 +893,28 @@ int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
     if (RedisModule_Init(ctx,"test",1,REDISMODULE_APIVER_1)
         == REDISMODULE_ERR) return REDISMODULE_ERR;
 
+    /* Perform RM_Call inside the RedisModule_OnLoad
+     * to verify that it works as expected without crashing.
+     * The tests will verify it on different configurations
+     * options (cluster/no cluster). A simple ping command
+     * is enough for this test. */
+    RedisModuleCallReply *reply = RedisModule_Call(ctx, "ping", "");
+    if (RedisModule_CallReplyType(reply) != REDISMODULE_REPLY_STRING) {
+        RedisModule_FreeCallReply(reply);
+        return REDISMODULE_ERR;
+    }
+    size_t len;
+    const char *reply_str = RedisModule_CallReplyStringPtr(reply, &len);
+    if (len != 4) {
+        RedisModule_FreeCallReply(reply);
+        return REDISMODULE_ERR;
+    }
+    if (memcmp(reply_str, "PONG", 4) != 0) {
+        RedisModule_FreeCallReply(reply);
+        return REDISMODULE_ERR;
+    }
+    RedisModule_FreeCallReply(reply);
+
     if (RedisModule_CreateCommand(ctx,"test.call",
         TestCall,"write deny-oom",1,1,1) == REDISMODULE_ERR)
         return REDISMODULE_ERR;

tests/unit/moduleapi/basics.tcl

@@ -38,4 +38,4 @@ start_server {tags {"modules external:skip"} overrides {enable-module-command no
     test {module command disabled} {
        assert_error "ERR *MODULE command not allowed*" {r module load $testmodule}
     }
-}
+}

tests/unit/moduleapi/cluster.tcl

@@ -163,3 +163,17 @@ start_cluster 3 0 [list config_lines $modules] {
     $node2_rd close
 }
 }
+
+set testmodule [file normalize tests/modules/basics.so]
+set modules [list loadmodule $testmodule]
+start_cluster 3 0 [list config_lines $modules] {
+    set node1 [srv 0 client]
+    set node2 [srv -1 client]
+    set node3 [srv -2 client]
+
+    test "Verify RM_Call inside module load function on cluster mode" {
+        assert_equal {PONG} [$node1 PING]
+        assert_equal {PONG} [$node2 PING]
+        assert_equal {PONG} [$node3 PING]
+    }
+}