fix: disallow empty tags

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required (VERSION 3.7)
 project(core
-        VERSION 0.3.2
+        VERSION 0.3.3
         LANGUAGES C)
 
 add_executable(core src/main.c)

src/endpoints/api_v1_tags.c

@@ -70,6 +70,16 @@ api_v1_tags_POST(struct mg_connection *nc, struct http_message *hm, endpoint_arg
         return;
     }
 
+    if(strlen(json_tag->valuestring) == 0)
+    {
+        LOGGER_DEBUG("tag is empty\n");
+        cJSON_Delete(json);
+
+        static const char content[] = "tag is empty";
+        endpoint_response_text(response, 400, content, STRLEN(content));
+        return;
+    }
+
     if(tag_save(0, json_tag->valuestring))
     {
         LOGGER_DEBUG("tag could not be saved\n");

src/models/tag.c

@@ -10,6 +10,11 @@
 int
 tag_save(int id, const char *tag)
 {
+    if(strlen(tag) == 0)
+    {
+        LOGGER_ERR("saving an empty tag is not allowed (id: %d)\n", id);
+        return 1;
+    }
     LOGGER_DEBUG("saving tag '%s' into database (id: %d)\n", tag, id);
 
     int rc;