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From: Laurent Vivier <lvivier@redhat.com>
To: passt-dev@passt.top
Cc: Laurent Vivier <lvivier@redhat.com>
Subject: [PATCH v3 02/11] tcp: extract buffer management from tcp_send_flag()
Date: Wed, 29 May 2024 12:19:00 +0200	[thread overview]
Message-ID: <20240529101909.1120078-3-lvivier@redhat.com> (raw)
In-Reply-To: <20240529101909.1120078-1-lvivier@redhat.com>

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 tcp.c | 87 ++++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 54 insertions(+), 33 deletions(-)

diff --git a/tcp.c b/tcp.c
index 6f221995f3bc..a6f43010f58f 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1518,24 +1518,25 @@ static void tcp_update_seqack_from_tap(const struct ctx *c,
 }
 
 /**
- * tcp_send_flag() - Send segment with flags to tap (no payload)
+ * tcp_fill_flag_header() - Prepare header for flags-only segment (no payload)
  * @c:		Execution context
  * @conn:	Connection pointer
  * @flags:	TCP flags: if not set, send segment only if ACK is due
+ * @th:		TCP header to update
+ * @data:	buffer to store TCP option
+ * @optlen:	size of the TCP option buffer
  *
- * Return: negative error code on connection reset, 0 otherwise
+ * Return: < 0 error code on connection reset,
+ *           0 if there is no flag to send
+ *	     1 otherwise
  */
-static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
+static int tcp_fill_flag_header(struct ctx *c, struct tcp_tap_conn *conn,
+				int flags, struct tcphdr *th, char *data,
+				size_t *optlen)
 {
-	struct tcp_flags_t *payload;
 	struct tcp_info tinfo = { 0 };
 	socklen_t sl = sizeof(tinfo);
 	int s = conn->sock;
-	size_t optlen = 0;
-	struct tcphdr *th;
-	struct iovec *iov;
-	size_t l4len;
-	char *data;
 
 	if (SEQ_GE(conn->seq_ack_to_tap, conn->seq_from_tap) &&
 	    !flags && conn->wnd_to_tap)
@@ -1557,20 +1558,11 @@ static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
 	if (!tcp_update_seqack_wnd(c, conn, flags, &tinfo) && !flags)
 		return 0;
 
-	if (CONN_V4(conn))
-		iov = tcp4_l2_flags_iov[tcp4_flags_used++];
-	else
-		iov = tcp6_l2_flags_iov[tcp6_flags_used++];
-
-	payload = iov[TCP_IOV_PAYLOAD].iov_base;
-	th = &payload->th;
-	data = payload->opts;
-
 	if (flags & SYN) {
 		int mss;
 
 		/* Options: MSS, NOP and window scale (8 bytes) */
-		optlen = OPT_MSS_LEN + 1 + OPT_WS_LEN;
+		*optlen = OPT_MSS_LEN + 1 + OPT_WS_LEN;
 
 		*data++ = OPT_MSS;
 		*data++ = OPT_MSS_LEN;
@@ -1604,26 +1596,13 @@ static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
 		flags |= ACK;
 	}
 
-	th->doff = (sizeof(*th) + optlen) / 4;
+	th->doff = (sizeof(*th) + *optlen) / 4;
 
 	th->ack = !!(flags & ACK);
 	th->rst = !!(flags & RST);
 	th->syn = !!(flags & SYN);
 	th->fin = !!(flags & FIN);
 
-	if (CONN_V4(conn)) {
-		l4len = tcp_fill_headers4(c, conn, iov[TCP_IOV_TAP].iov_base,
-					  iov[TCP_IOV_IP].iov_base,
-					  iov[TCP_IOV_PAYLOAD].iov_base, optlen,
-					  NULL, conn->seq_to_tap);
-	} else {
-		l4len = tcp_fill_headers6(c, conn, iov[TCP_IOV_TAP].iov_base,
-					  iov[TCP_IOV_IP].iov_base,
-					  iov[TCP_IOV_PAYLOAD].iov_base, optlen,
-					  conn->seq_to_tap);
-	}
-	iov[TCP_IOV_PAYLOAD].iov_len = l4len;
-
 	if (th->ack) {
 		if (SEQ_GE(conn->seq_ack_to_tap, conn->seq_from_tap))
 			conn_flag(c, conn, ~ACK_TO_TAP_DUE);
@@ -1638,6 +1617,48 @@ static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
 	if (th->fin || th->syn)
 		conn->seq_to_tap++;
 
+	return 1;
+}
+
+static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
+{
+	struct tcp_flags_t *payload;
+	size_t optlen = 0;
+	struct iovec *iov;
+	size_t l4len;
+	int ret;
+
+	if (CONN_V4(conn)) {
+		iov = tcp4_l2_flags_iov[tcp4_flags_used++];
+
+		payload = iov[TCP_IOV_PAYLOAD].iov_base;
+
+		ret = tcp_fill_flag_header(c, conn, flags, &payload->th,
+					   payload->opts, &optlen);
+		if (ret <= 0)
+			return ret;
+
+		l4len = tcp_fill_headers4(c, conn, iov[TCP_IOV_TAP].iov_base,
+					  iov[TCP_IOV_IP].iov_base,
+					  iov[TCP_IOV_PAYLOAD].iov_base, optlen,
+					  NULL, conn->seq_to_tap);
+	} else {
+		iov = tcp6_l2_flags_iov[tcp6_flags_used++];
+
+		payload = iov[TCP_IOV_PAYLOAD].iov_base;
+
+		ret = tcp_fill_flag_header(c, conn, flags, &payload->th,
+					   payload->opts, &optlen);
+		if (ret <= 0)
+			return ret;
+
+		l4len = tcp_fill_headers6(c, conn, iov[TCP_IOV_TAP].iov_base,
+					  iov[TCP_IOV_IP].iov_base,
+					  iov[TCP_IOV_PAYLOAD].iov_base, optlen,
+					  conn->seq_to_tap);
+	}
+	iov[TCP_IOV_PAYLOAD].iov_len = l4len;
+
 	if (flags & DUP_ACK) {
 		struct iovec *dup_iov;
 		int i;
-- 
@@ -1518,24 +1518,25 @@ static void tcp_update_seqack_from_tap(const struct ctx *c,
 }
 
 /**
- * tcp_send_flag() - Send segment with flags to tap (no payload)
+ * tcp_fill_flag_header() - Prepare header for flags-only segment (no payload)
  * @c:		Execution context
  * @conn:	Connection pointer
  * @flags:	TCP flags: if not set, send segment only if ACK is due
+ * @th:		TCP header to update
+ * @data:	buffer to store TCP option
+ * @optlen:	size of the TCP option buffer
  *
- * Return: negative error code on connection reset, 0 otherwise
+ * Return: < 0 error code on connection reset,
+ *           0 if there is no flag to send
+ *	     1 otherwise
  */
-static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
+static int tcp_fill_flag_header(struct ctx *c, struct tcp_tap_conn *conn,
+				int flags, struct tcphdr *th, char *data,
+				size_t *optlen)
 {
-	struct tcp_flags_t *payload;
 	struct tcp_info tinfo = { 0 };
 	socklen_t sl = sizeof(tinfo);
 	int s = conn->sock;
-	size_t optlen = 0;
-	struct tcphdr *th;
-	struct iovec *iov;
-	size_t l4len;
-	char *data;
 
 	if (SEQ_GE(conn->seq_ack_to_tap, conn->seq_from_tap) &&
 	    !flags && conn->wnd_to_tap)
@@ -1557,20 +1558,11 @@ static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
 	if (!tcp_update_seqack_wnd(c, conn, flags, &tinfo) && !flags)
 		return 0;
 
-	if (CONN_V4(conn))
-		iov = tcp4_l2_flags_iov[tcp4_flags_used++];
-	else
-		iov = tcp6_l2_flags_iov[tcp6_flags_used++];
-
-	payload = iov[TCP_IOV_PAYLOAD].iov_base;
-	th = &payload->th;
-	data = payload->opts;
-
 	if (flags & SYN) {
 		int mss;
 
 		/* Options: MSS, NOP and window scale (8 bytes) */
-		optlen = OPT_MSS_LEN + 1 + OPT_WS_LEN;
+		*optlen = OPT_MSS_LEN + 1 + OPT_WS_LEN;
 
 		*data++ = OPT_MSS;
 		*data++ = OPT_MSS_LEN;
@@ -1604,26 +1596,13 @@ static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
 		flags |= ACK;
 	}
 
-	th->doff = (sizeof(*th) + optlen) / 4;
+	th->doff = (sizeof(*th) + *optlen) / 4;
 
 	th->ack = !!(flags & ACK);
 	th->rst = !!(flags & RST);
 	th->syn = !!(flags & SYN);
 	th->fin = !!(flags & FIN);
 
-	if (CONN_V4(conn)) {
-		l4len = tcp_fill_headers4(c, conn, iov[TCP_IOV_TAP].iov_base,
-					  iov[TCP_IOV_IP].iov_base,
-					  iov[TCP_IOV_PAYLOAD].iov_base, optlen,
-					  NULL, conn->seq_to_tap);
-	} else {
-		l4len = tcp_fill_headers6(c, conn, iov[TCP_IOV_TAP].iov_base,
-					  iov[TCP_IOV_IP].iov_base,
-					  iov[TCP_IOV_PAYLOAD].iov_base, optlen,
-					  conn->seq_to_tap);
-	}
-	iov[TCP_IOV_PAYLOAD].iov_len = l4len;
-
 	if (th->ack) {
 		if (SEQ_GE(conn->seq_ack_to_tap, conn->seq_from_tap))
 			conn_flag(c, conn, ~ACK_TO_TAP_DUE);
@@ -1638,6 +1617,48 @@ static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
 	if (th->fin || th->syn)
 		conn->seq_to_tap++;
 
+	return 1;
+}
+
+static int tcp_send_flag(struct ctx *c, struct tcp_tap_conn *conn, int flags)
+{
+	struct tcp_flags_t *payload;
+	size_t optlen = 0;
+	struct iovec *iov;
+	size_t l4len;
+	int ret;
+
+	if (CONN_V4(conn)) {
+		iov = tcp4_l2_flags_iov[tcp4_flags_used++];
+
+		payload = iov[TCP_IOV_PAYLOAD].iov_base;
+
+		ret = tcp_fill_flag_header(c, conn, flags, &payload->th,
+					   payload->opts, &optlen);
+		if (ret <= 0)
+			return ret;
+
+		l4len = tcp_fill_headers4(c, conn, iov[TCP_IOV_TAP].iov_base,
+					  iov[TCP_IOV_IP].iov_base,
+					  iov[TCP_IOV_PAYLOAD].iov_base, optlen,
+					  NULL, conn->seq_to_tap);
+	} else {
+		iov = tcp6_l2_flags_iov[tcp6_flags_used++];
+
+		payload = iov[TCP_IOV_PAYLOAD].iov_base;
+
+		ret = tcp_fill_flag_header(c, conn, flags, &payload->th,
+					   payload->opts, &optlen);
+		if (ret <= 0)
+			return ret;
+
+		l4len = tcp_fill_headers6(c, conn, iov[TCP_IOV_TAP].iov_base,
+					  iov[TCP_IOV_IP].iov_base,
+					  iov[TCP_IOV_PAYLOAD].iov_base, optlen,
+					  conn->seq_to_tap);
+	}
+	iov[TCP_IOV_PAYLOAD].iov_len = l4len;
+
 	if (flags & DUP_ACK) {
 		struct iovec *dup_iov;
 		int i;
-- 
2.44.0


  parent reply	other threads:[~2024-05-29 10:19 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-05-29 10:18 [PATCH v3 00/11] Add vhost-user support to passt (part 2) Laurent Vivier
2024-05-29 10:18 ` [PATCH v3 01/11] tcp: inline tcp_l2_buf_fill_headers() Laurent Vivier
2024-05-31  5:22   ` David Gibson
2024-05-29 10:19 ` Laurent Vivier [this message]
2024-05-29 10:19 ` [PATCH v3 03/11] tcp: extract buffer management from tcp_conn_tap_mss() Laurent Vivier
2024-05-29 10:19 ` [PATCH v3 04/11] tcp: move buffers management functions to their own file Laurent Vivier
2024-05-29 10:19 ` [PATCH v3 05/11] tap: export pool_flush()/tapX_handler()/packet_add() Laurent Vivier
2024-05-29 10:19 ` [PATCH v3 06/11] udp: move udpX_l2_buf_t and udpX_l2_mh_sock out of udp_update_hdrX() Laurent Vivier
2024-05-29 10:19 ` [PATCH v3 07/11] udp: rename udp_sock_handler() to udp_buf_sock_handler() Laurent Vivier
2024-05-29 10:19 ` [PATCH v3 08/11] vhost-user: compare mode MODE_PASTA and not MODE_PASST Laurent Vivier
2024-05-29 10:19 ` [PATCH v3 09/11] iov: remove iov_copy() Laurent Vivier
2024-05-29 10:19 ` [PATCH v3 10/11] tcp: remove tap_hdr parameter Laurent Vivier
2024-05-29 10:19 ` [PATCH v3 11/11] tap: use in->buf_size rather than sizeof(pkt_buf) Laurent Vivier

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