counters: improve handling missing global config

Improve warnings when eve.stats can't work because of the global config
missing or disabled.

Issue warning if global config is missing but stats are still enabled due
to the legacy stats.log.

Issue clearer warning when stats are disabled and unix socket dump-counters
command is issued.

Warnings include links to docs.

Bug #2465.

src/counters.c

@@ -245,6 +245,14 @@ static void StatsInitCtxPreOutput(void)
             SCLogDebug("Stats module has been disabled");
             SCReturn;
         }
+        /* warn if we are using legacy config to enable stats */
+        ConfNode *gstats = ConfGetNode("stats");
+        if (gstats == NULL) {
+            SCLogWarning(SC_ERR_STATS_LOG_GENERIC, "global stats config is missing. "
+                    "Stats enabled through legacy stats.log. "
+                    "See %s%s/configuration/suricata-yaml.html#stats", DOC_URL, DOC_VERSION);
+        }
+
         const char *interval = ConfNodeLookupChildValue(stats, "interval");
         if (interval != NULL)
             stats_tts = (uint32_t) atoi(interval);
@@ -280,7 +288,7 @@ static void StatsInitCtxPostOutput(void)
         exit(EXIT_FAILURE);
     }
 
-    if (!OutputStatsLoggersRegistered()) {
+    if (stats_enabled && !OutputStatsLoggersRegistered()) {
         stats_loggers_active = 0;
 
         /* if the unix command socket is enabled we do the background
@@ -809,6 +817,10 @@ TmEcode StatsOutputCounterSocket(json_t *cmd,
     json_t *message = NULL;
     TmEcode r = TM_ECODE_OK;
 
+    if (!stats_enabled) {
+        r = TM_ECODE_FAILED;
+        message = json_string("stats are disabled in the config");
+    } else {
         SCMutexLock(&stats_table_mutex);
         if (stats_table.start_time == 0) {
             r = TM_ECODE_FAILED;
@@ -817,7 +829,7 @@ TmEcode StatsOutputCounterSocket(json_t *cmd,
             message = StatsToJSON(&stats_table, JSON_STATS_TOTALS|JSON_STATS_THREADS);
         }
         SCMutexUnlock(&stats_table_mutex);
-
+    }
     json_object_set_new(answer, "message", message);
     return r;
 }

src/output-json-stats.c

@@ -383,6 +383,14 @@ static void OutputStatsLogDeinit(OutputCtx *output_ctx)
 static OutputInitResult OutputStatsLogInit(ConfNode *conf)
 {
     OutputInitResult result = { NULL, false };
+
+    if (!StatsEnabled()) {
+        SCLogError(SC_ERR_STATS_LOG_GENERIC,
+                "stats.json: stats are disabled globally: set stats.enabled to true. "
+                "See %s%s/configuration/suricata-yaml.html#stats", DOC_URL, DOC_VERSION);
+        return result;
+    }
+
     LogFileCtx *file_ctx = LogFileNewCtx();
     if(file_ctx == NULL) {
         SCLogError(SC_ERR_STATS_LOG_GENERIC, "couldn't create new file_ctx");
@@ -455,6 +463,14 @@ static OutputInitResult OutputStatsLogInitSub(ConfNode *conf, OutputCtx *parent_
 {
     OutputInitResult result = { NULL, false };
     OutputJsonCtx *ajt = parent_ctx->data;
+
+    if (!StatsEnabled()) {
+        SCLogError(SC_ERR_STATS_LOG_GENERIC,
+                "eve.stats: stats are disabled globally: set stats.enabled to true. "
+                "See %s%s/configuration/suricata-yaml.html#stats", DOC_URL, DOC_VERSION);
+        return result;
+    }
+
     OutputStatsCtx *stats_ctx = SCMalloc(sizeof(OutputStatsCtx));
     if (unlikely(stats_ctx == NULL))
         return result;