[RFC v2 03/11] tap: replace tx tap hdr with virtio_nethdr_mrg_rxbuf

["Eugenio Pérez" <eperezma@redhat.com>]

vhost kernel expects this as the first data of the frame.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 tap.c     |  2 +-
 tcp_buf.c | 15 +++++++++++++--
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/tap.c b/tap.c
index 0c49e6d..0656294 100644
--- a/tap.c
+++ b/tap.c
@@ -593,7 +593,7 @@ size_t tap_send_frames(const struct ctx *c, const struct iovec *iov,
 		      nframes - m, nframes);

 	pcap_multiple(iov, bufs_per_frame, m,
-		      c->mode == MODE_PASST ? sizeof(uint32_t) : 0);
+		      c->mode == MODE_PASST ? sizeof(uint32_t) : sizeof(struct virtio_net_hdr_mrg_rxbuf));

 	return m;
 }
diff --git a/tcp_buf.c b/tcp_buf.c
index d1fca67..2fbd056 100644
--- a/tcp_buf.c
+++ b/tcp_buf.c
@@ -22,6 +22,8 @@

 #include <netinet/tcp.h>

+#include <linux/virtio_net.h>
+
 #include "util.h"
 #include "ip.h"
 #include "iov.h"
@@ -43,7 +45,7 @@
 static struct ethhdr		tcp4_eth_src;
 static struct ethhdr		tcp6_eth_src;

-static struct tap_hdr		tcp_payload_tap_hdr[TCP_FRAMES_MEM];
+static struct virtio_net_hdr_mrg_rxbuf tcp_payload_tap_hdr[TCP_FRAMES_MEM];

 /* IP headers for IPv4 and IPv6 */
 struct iphdr		tcp4_payload_ip[TCP_FRAMES_MEM];
@@ -75,6 +77,14 @@ void tcp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s)
 	eth_update_mac(&tcp6_eth_src, eth_d, eth_s);
 }

+static inline struct iovec virtio_net_hdr_iov(struct virtio_net_hdr_mrg_rxbuf *hdr)
+{
+        return (struct iovec){
+                .iov_base = hdr,
+                .iov_len = sizeof(*hdr),
+        };
+}
+
 /**
  * tcp_sock_iov_init() - Initialise scatter-gather L2 buffers for IPv4 sockets
  * @c:		Execution context
@@ -85,6 +95,7 @@ void tcp_sock_iov_init(const struct ctx *c)
 	struct iphdr iph = L2_BUF_IP4_INIT(IPPROTO_TCP);
 	int i;

+	(void)c;
 	tcp6_eth_src.h_proto = htons_constant(ETH_P_IPV6);
 	tcp4_eth_src.h_proto = htons_constant(ETH_P_IP);

@@ -96,7 +107,7 @@ void tcp_sock_iov_init(const struct ctx *c)
 	for (i = 0; i < TCP_FRAMES_MEM; i++) {
 		struct iovec *iov = tcp_l2_iov[i];

-		iov[TCP_IOV_TAP] = tap_hdr_iov(c, &tcp_payload_tap_hdr[i]);
+		iov[TCP_IOV_TAP] = virtio_net_hdr_iov(&tcp_payload_tap_hdr[i]);
 		iov[TCP_IOV_ETH].iov_len = sizeof(struct ethhdr);
 		iov[TCP_IOV_PAYLOAD].iov_base = &tcp_payload[i];
 	}
--
2.50.0