permissions: safety check for trusted hash table

- avoid crash if a db reload is issued in db-only mode
- reported Emmanuel Schmidbauer, GH #228

(cherry picked from commit f2958e5)
(cherry picked from commit 02ba3dd)

modules/permissions/trusted.c

@@ -43,9 +43,9 @@
 
 #define TABLE_VERSION 5
 
-struct trusted_list ***hash_table;     /* Pointer to current hash table pointer */
-struct trusted_list **hash_table_1;   /* Pointer to hash table 1 */
-struct trusted_list **hash_table_2;   /* Pointer to hash table 2 */
+struct trusted_list ***hash_table = 0;    /* Pointer to current hash table pointer */
+struct trusted_list **hash_table_1 = 0;   /* Pointer to hash table 1 */
+struct trusted_list **hash_table_2 = 0;   /* Pointer to hash table 2 */
 
 
 static db1_con_t* db_handle = 0;
@@ -69,16 +69,21 @@ int reload_trusted_table(void)
 
 	char *pattern, *tag;
 
-	cols[0] = &source_col;
-	cols[1] = &proto_col;
-	cols[2] = &from_col;
-	cols[3] = &tag_col;
+	if (hash_table == 0) {
+	    LM_ERR("in-memory hash table not initialized\n");
+	    return -1;
+	}
 
 	if (db_handle == 0) {
 	    LM_ERR("no connection to database\n");
 	    return -1;
 	}
 
+	cols[0] = &source_col;
+	cols[1] = &proto_col;
+	cols[2] = &from_col;
+	cols[3] = &tag_col;
+
 	if (perm_dbf.use_table(db_handle, &trusted_table) < 0) {
 		LM_ERR("failed to use trusted table\n");
 		return -1;