MINOR: mux_quic: report fatal error on QMux frame type parsing issue

QMux frames are now enclosed in an intermediary Record layer. A benefit
of this change is that this ensures frames will be wholly read.

As such, qc_parse_frm_type() should not fail anymore when parsing QMux
frames due to an incomplete type field. In this case, rxbuf is now
cleared and a fatal error is reported to the caller.

Author: a-denoyelle

src/qcm_qmux.c

@@ -46,8 +46,11 @@ static int qmux_parse_frm(struct qcc *qcc, struct buffer *buf)
 	old = pos = (unsigned char *)b_head(buf);
 	end = (unsigned char *)b_head(buf) + b_data(buf);
 	ret = qc_parse_frm_type(&frm, &pos, end, NULL);
-	if (!ret)
-		return 0;
+	if (!ret) {
+		/* TODO close connection with FRAME_ENCODING_ERROR */
+		b_reset(buf);
+		return -1;
+	}
 
 	if (!qmux_is_frm_valid(&frm)) {
 		/* TODO close connection with FRAME_ENCODING_ERROR */