add: endpoint /tags

fix: leaks from config (now using static length for config strings)

endpoints/api_v1_tags.c

@@ -0,0 +1,35 @@
+#include <cJSON.h>
+#include <macros.h>
+#include <constants.h>
+#include <endpoints/api_v1_tags.h>
+#include <logger.h>
+#include <models/tag.h>
+
+void
+api_v1_tags_GET(struct mg_connection *nc, struct http_message *hm, endpoint_args_t *args, endpoint_response_t *response)
+{
+    (void)args;
+    (void)hm;
+    (void)nc;
+
+    char** all_tags = tag_get_all();
+
+    cJSON *json = cJSON_CreateArray();
+
+    for(int i = 0; all_tags[i] != NULL; ++i)
+    {
+        cJSON *json_tag = cJSON_CreateString(all_tags[i]);
+        if (json_tag == NULL)
+        {
+            LOG_DEBUG("failed to add tag from string '%s'\n", all_tags[i]);
+            free(all_tags[i]);
+            continue;
+        }
+        cJSON_AddItemToArray(json, json_tag);
+        free(all_tags[i]);
+    }
+
+    endpoint_response_json(response, 200, json);
+    cJSON_Delete(json);
+    free(all_tags);
+}