MINOR: quic: extend qc_send_mux() return type with a dedicated enum

This commit is part of a adjustment on QUIC transport send API to
support pacing. Here, qc_send_mux() return type has been changed to use
a new enum quic_tx_err.

This is useful to explain different failure causes of emission. For now,
only two values have been defined : NONE and FATAL. When pacing will be
implemented, a new value would be added to specify that emission was
interrupted on pacing. This won't be a fatal error as this allows to
retry emission but not immediately.

Author: a-denoyelle

include/haproxy/quic_tx-t.h

@@ -64,4 +64,9 @@ enum qc_build_pkt_err {
 	QC_BUILD_PKT_ERR_BUFROOM,  /* no more room in input buf or congestion window */
 };
 
+enum quic_tx_err {
+	QUIC_TX_ERR_NONE,
+	QUIC_TX_ERR_FATAL,
+};
+
 #endif /* _HAPROXY_TX_T_H */

include/haproxy/quic_tx.h

@@ -33,7 +33,7 @@ void qc_txb_release(struct quic_conn *qc);
 int qc_purge_txbuf(struct quic_conn *qc, struct buffer *buf);
 struct buffer *qc_get_txb(struct quic_conn *qc);
 
-int qc_send_mux(struct quic_conn *qc, struct list *frms);
+enum quic_tx_err qc_send_mux(struct quic_conn *qc, struct list *frms);
 
 void qel_register_send(struct list *send_list, struct quic_enc_level *qel,
                        struct list *frms);

src/mux_quic.c

@@ -2074,14 +2074,17 @@ static int qcc_subscribe_send(struct qcc *qcc)
  */
 static int qcc_send_frames(struct qcc *qcc, struct list *frms)
 {
+	enum quic_tx_err ret;
+
 	TRACE_ENTER(QMUX_EV_QCC_SEND, qcc->conn);
 
 	if (LIST_ISEMPTY(frms)) {
 		TRACE_DEVEL("leaving on no frame to send", QMUX_EV_QCC_SEND, qcc->conn);
 		return 1;
 	}
 
-	if (!qc_send_mux(qcc->conn->handle.qc, frms)) {
+	ret = qc_send_mux(qcc->conn->handle.qc, frms);
+	if (ret == QUIC_TX_ERR_FATAL) {
 		TRACE_DEVEL("error on sending", QMUX_EV_QCC_SEND, qcc->conn);
 		qcc_subscribe_send(qcc);
 		goto err;

src/quic_tx.c

@@ -469,18 +469,19 @@ int qc_purge_txbuf(struct quic_conn *qc, struct buffer *buf)
  *
  * Returns the result from qc_send() function.
  */
-int qc_send_mux(struct quic_conn *qc, struct list *frms)
+enum quic_tx_err qc_send_mux(struct quic_conn *qc, struct list *frms)
 {
 	struct list send_list = LIST_HEAD_INIT(send_list);
-	int ret;
+	enum quic_tx_err ret = QUIC_TX_ERR_NONE;
+	int sent;
 
 	TRACE_ENTER(QUIC_EV_CONN_TXPKT, qc);
 	BUG_ON(qc->mux_state != QC_MUX_READY); /* Only MUX can uses this function so it must be ready. */
 
 	if (qc->conn->flags & CO_FL_SOCK_WR_SH) {
 		qc->conn->flags |= CO_FL_ERROR | CO_FL_SOCK_RD_SH;
 		TRACE_DEVEL("connection on error", QUIC_EV_CONN_TXPKT, qc);
-		return 0;
+		return QUIC_TX_ERR_FATAL;
 	}
 
 	/* Try to send post handshake frames first unless on 0-RTT. */
@@ -493,7 +494,9 @@ int qc_send_mux(struct quic_conn *qc, struct list *frms)
 
 	TRACE_STATE("preparing data (from MUX)", QUIC_EV_CONN_TXPKT, qc);
 	qel_register_send(&send_list, qc->ael, frms);
-	ret = qc_send(qc, 0, &send_list, 0);
+	sent = qc_send(qc, 0, &send_list, 0);
+	if (sent <= 0)
+		ret = QUIC_TX_ERR_FATAL;
 
 	TRACE_LEAVE(QUIC_EV_CONN_TXPKT, qc);
 	return ret;