in_forward: Handle '' and "" or absent value for yaml value as an empty shared_key

Signed-off-by: Hiroshi Hatake <[email protected]>

Author: cosmo0920

plugins/in_forward/fw_config.c

@@ -88,10 +88,21 @@ struct flb_in_fw_config *fw_config_init(struct flb_input_instance *i_ins)
     /* Shared Key */
     p = flb_input_get_property("shared_key", i_ins);
     if (p) {
-        config->shared_key = flb_sds_create(p);
+        if (strcmp(p, "\'\'") == 0 || strcmp(p, "\"\"") == 0) {
+            config->shared_key = flb_sds_create("");
+        }
+        else {
+            config->shared_key = flb_sds_create(p);
+        }
     }
     else {
-        config->shared_key = NULL;
+        config->shared_key = flb_sds_create("");
+    }
+    if (config->shared_key == NULL) {
+        flb_plg_error(i_ins, "could not initialize shared_key");
+        fw_config_destroy(config);
+
+        return NULL;
     }
 
     /* Self Hostname */