multi-detect: make classification prefix aware

Make classification 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.

src/util-classification-config.c

@@ -54,7 +54,7 @@ uint32_t SCClassConfClasstypeHashFunc(HashTable *ht, void *data, uint16_t datale
 char SCClassConfClasstypeHashCompareFunc(void *data1, uint16_t datalen1,
                                          void *data2, uint16_t datalen2);
 void SCClassConfClasstypeHashFree(void *ch);
-static char *SCClassConfGetConfFilename(void);
+static char *SCClassConfGetConfFilename(const DetectEngineCtx *de_ctx);
 
 void SCClassConfInit(void)
 {
@@ -124,7 +124,7 @@ FILE *SCClassConfInitContextAndLocalResources(DetectEngineCtx *de_ctx, FILE *fd)
      * instead use an input stream against a buffer containing the
      * classification strings */
     if (fd == NULL) {
-        filename = SCClassConfGetConfFilename();
+        filename = SCClassConfGetConfFilename(de_ctx);
         if ( (fd = fopen(filename, "r")) == NULL) {
 #ifdef UNITTESTS
             if (RunmodeIsUnittests())
@@ -160,12 +160,26 @@ FILE *SCClassConfInitContextAndLocalResources(DetectEngineCtx *de_ctx, FILE *fd)
  * \retval log_filename Pointer to a string containing the path for the
  *                      Classification Config file.
  */
-static char *SCClassConfGetConfFilename(void)
+static char *SCClassConfGetConfFilename(const DetectEngineCtx *de_ctx)
 {
     char *log_filename = NULL;
-
-    if (ConfGet("classification-file", &log_filename) != 1) {
-        log_filename = (char *)SC_CLASS_CONF_DEF_CONF_FILEPATH;
+    char config_value[256] = "";
+
+    if (de_ctx != NULL && strlen(de_ctx->config_prefix) > 0) {
+        snprintf(config_value, sizeof(config_value),
+                 "%s.classification-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("classification-file", &log_filename) != 1) {
+                log_filename = (char *)SC_CLASS_CONF_DEF_CONF_FILEPATH;
+            }
+        }
+    } else {
+        if (ConfGet("classification-file", &log_filename) != 1) {
+            log_filename = (char *)SC_CLASS_CONF_DEF_CONF_FILEPATH;
+        }
     }
 
     return log_filename;