multi-detect: make threshold prefix aware

Make threshold loading prefix aware, so it can be part of tenant
configuration.

If the setting is missing from the tenant, the global setting is tried
and if that too is missing, the global default is used.

Note: currently per host thresholds are tracked globally and NOT per
tenant.

src/util-threshold-config.c

@@ -103,14 +103,27 @@ static pcre_extra *regex_suppress_study = NULL;
  * \retval log_filename Pointer to a string containing the path for the
  *                      Threshold Config file.
  */
-char *SCThresholdConfGetConfFilename(void)
+static char *SCThresholdConfGetConfFilename(const DetectEngineCtx *de_ctx)
 {
     char *log_filename = NULL;
+    char config_value[256] = "";
 
-    if (ConfGet("threshold-file", &log_filename) != 1) {
-        log_filename = (char *)THRESHOLD_CONF_DEF_CONF_FILEPATH;
-    }
+    if (de_ctx != NULL && strlen(de_ctx->config_prefix) > 0) {
+        snprintf(config_value, sizeof(config_value),
+                 "%s.threshold-file", de_ctx->config_prefix);
 
+        /* try loading prefix setting, fall back to global if that
+         * fails. */
+        if (ConfGet(config_value, &log_filename) != 1) {
+            if (ConfGet("threshold-file", &log_filename) != 1) {
+                log_filename = (char *)THRESHOLD_CONF_DEF_CONF_FILEPATH;
+            }
+        }
+    } else {
+        if (ConfGet("threshold-file", &log_filename) != 1) {
+            log_filename = (char *)THRESHOLD_CONF_DEF_CONF_FILEPATH;
+        }
+    }
     return log_filename;
 }
 
@@ -138,7 +151,7 @@ int SCThresholdConfInitContext(DetectEngineCtx *de_ctx, FILE *utfd)
     int opts = 0;
 
     if (fd == NULL) {
-        filename = SCThresholdConfGetConfFilename();
+        filename = SCThresholdConfGetConfFilename(de_ctx);
         if ( (fd = fopen(filename, "r")) == NULL) {
             SCLogWarning(SC_ERR_FOPEN, "Error opening file: \"%s\": %s", filename, strerror(errno));
             goto error;
@@ -212,7 +225,6 @@ error:
  */
 void SCThresholdConfDeInitContext(DetectEngineCtx *de_ctx, FILE *fd)
 {
-
     if (fd != NULL)
         fclose(fd);