Restore negotiated settings copy

include/aws/mqtt/v5/mqtt5_client.h

@@ -787,6 +787,20 @@ AWS_MQTT_API int aws_mqtt5_negotiated_settings_init(
     struct aws_mqtt5_negotiated_settings *negotiated_settings,
     const struct aws_byte_cursor *client_id);
 
+/**
+ * Makes an owning copy of a negotiated settings structure.
+ *
+ * @param source settings to copy from
+ * @param dest settings to copy into.  Must be in a zeroed or initialized state because it gets clean up
+ *  called on it as the first step of the copy process.
+ * @return success/failure
+ *
+ * Used in downstream.
+ */
+AWS_MQTT_API int aws_mqtt5_negotiated_settings_copy(
+    const struct aws_mqtt5_negotiated_settings *source,
+    struct aws_mqtt5_negotiated_settings *dest);
+
 /**
  * Clean up owned memory in negotiated_settings
  *

source/v5/mqtt5_utils.c

@@ -123,6 +123,24 @@ int aws_mqtt5_negotiated_settings_init(
     return AWS_OP_SUCCESS;
 }
 
+int aws_mqtt5_negotiated_settings_copy(
+    const struct aws_mqtt5_negotiated_settings *source,
+    struct aws_mqtt5_negotiated_settings *dest) {
+    aws_mqtt5_negotiated_settings_clean_up(dest);
+
+    *dest = *source;
+    AWS_ZERO_STRUCT(dest->client_id_storage);
+
+    if (source->client_id_storage.allocator != NULL) {
+        return aws_byte_buf_init_copy_from_cursor(
+            &dest->client_id_storage,
+            source->client_id_storage.allocator,
+            aws_byte_cursor_from_buf(&source->client_id_storage));
+    }
+
+    return AWS_OP_SUCCESS;
+}
+
 int aws_mqtt5_negotiated_settings_apply_client_id(
     struct aws_mqtt5_negotiated_settings *negotiated_settings,
     const struct aws_byte_cursor *client_id) {