+struct ofpbuf *ofputil_encode_error_msg(int error, const struct ofp_header *);
+int ofputil_decode_error_msg(const struct ofp_header *, size_t *payload_ofs);
+
+/* String versions of errors. */
+void ofputil_format_error(struct ds *, int error);
+char *ofputil_error_to_string(int error);