tcp: Use abstracted tap header

Update the TCP code to use the tap layer abstractions for initializing and
updating the L2 and lower headers.  This will make adding other tap
backends in future easier.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 30 insertions, 55 deletions

diff --git a/tcp.c b/tcp.c
index f812143..1e0a338 100644
--- a/tcp.c
+++ b/tcp.c
@@ -330,8 +330,7 @@ struct tcp4_l2_head {	/* For MSS4 macro: keep in sync with tcp4_l2_buf_t */
 #else
 	uint8_t pad[2];
 #endif
-	uint32_t vnet_len;
-	struct ethhdr eh;
+	struct tap_hdr taph;
 	struct iphdr iph;
 	struct tcphdr th;
 #ifdef __AVX2__
@@ -346,8 +345,7 @@ struct tcp6_l2_head {	/* For MSS6 macro: keep in sync with tcp6_l2_buf_t */
 #else
 	uint8_t pad[2];
 #endif
-	uint32_t vnet_len;
-	struct ethhdr eh;
+	struct tap_hdr taph;
 	struct ipv6hdr ip6h;
 	struct tcphdr th;
 #ifdef __AVX2__
@@ -448,8 +446,7 @@ static union inany_addr low_rtt_dst[LOW_RTT_TABLE_SIZE];
  * @psum:	Partial IP header checksum (excluding tot_len and saddr)
  * @tsum:	Partial TCP header checksum (excluding length and saddr)
  * @pad:	Align TCP header to 32 bytes, for AVX2 checksum calculation only
- * @vnet_len:	4-byte qemu vnet buffer length descriptor, only for passt mode
- * @eh:		Pre-filled Ethernet header
+ * @taph:	Tap-level headers (partially pre-filled)
  * @iph:	Pre-filled IP header (except for tot_len and saddr)
  * @uh:		Headroom for TCP header
  * @data:	Storage for TCP payload
@@ -462,8 +459,7 @@ static struct tcp4_l2_buf_t {
 #else
 	uint8_t pad[2];		/*	align iph to 4 bytes	8 */
 #endif
-	uint32_t vnet_len;	/* 26				10 */
-	struct ethhdr eh;	/* 30				14 */
+	struct tap_hdr taph;	/* 26				10 */
 	struct iphdr iph;	/* 44				28 */
 	struct tcphdr th;	/* 64				48 */
 	uint8_t data[MSS4];	/* 84				68 */
@@ -480,8 +476,7 @@ static unsigned int tcp4_l2_buf_used;
 /**
  * tcp6_l2_buf_t - Pre-cooked IPv6 packet buffers for tap connections
  * @pad:	Align IPv6 header for checksum calculation to 32B (AVX2) or 4B
- * @vnet_len:	4-byte qemu vnet buffer length descriptor, only for passt mode
- * @eh:		Pre-filled Ethernet header
+ * @taph:	Tap-level headers (partially pre-filled)
  * @ip6h:	Pre-filled IP header (except for payload_len and addresses)
  * @th:		Headroom for TCP header
  * @data:	Storage for TCP payload
@@ -492,8 +487,7 @@ struct tcp6_l2_buf_t {
 #else
 	uint8_t pad[2];		/*	align ip6h to 4 bytes	0 */
 #endif
-	uint32_t vnet_len;	/* 14				2 */
-	struct ethhdr eh;	/* 18				6 */
+	struct tap_hdr taph;	/* 14				2 */
 	struct ipv6hdr ip6h;	/* 32				20 */
 	struct tcphdr th;	/* 72				60 */
 	uint8_t data[MSS6];	/* 92				80 */
@@ -526,8 +520,7 @@ static struct iovec	tcp_iov			[UIO_MAXIOV];
  * @psum:	Partial IP header checksum (excluding tot_len and saddr)
  * @tsum:	Partial TCP header checksum (excluding length and saddr)
  * @pad:	Align TCP header to 32 bytes, for AVX2 checksum calculation only
- * @vnet_len:	4-byte qemu vnet buffer length descriptor, only for passt mode
- * @eh:		Pre-filled Ethernet header
+ * @taph:	Tap-level headers (partially pre-filled)
  * @iph:	Pre-filled IP header (except for tot_len and saddr)
  * @th:		Headroom for TCP header
  * @opts:	Headroom for TCP options
@@ -540,8 +533,7 @@ static struct tcp4_l2_flags_buf_t {
 #else
 	uint8_t pad[2];		/*	align iph to 4 bytes	8 */
 #endif
-	uint32_t vnet_len;	/* 26				10 */
-	struct ethhdr eh;	/* 30				14 */
+	struct tap_hdr taph;	/* 26				10 */
 	struct iphdr iph;	/* 44				28 */
 	struct tcphdr th;	/* 64				48 */
 	char opts[OPT_MSS_LEN + OPT_WS_LEN + 1];
@@ -557,8 +549,7 @@ static unsigned int tcp4_l2_flags_buf_used;
 /**
  * tcp6_l2_flags_buf_t - IPv6 packet buffers for segments without data (flags)
  * @pad:	Align IPv6 header for checksum calculation to 32B (AVX2) or 4B
- * @vnet_len:	4-byte qemu vnet buffer length descriptor, only for passt mode
- * @eh:		Pre-filled Ethernet header
+ * @taph:	Tap-level headers (partially pre-filled)
  * @ip6h:	Pre-filled IP header (except for payload_len and addresses)
  * @th:		Headroom for TCP header
  * @opts:	Headroom for TCP options
@@ -569,8 +560,7 @@ static struct tcp6_l2_flags_buf_t {
 #else
 	uint8_t pad[2];		/*	align ip6h to 4 bytes		   0 */
 #endif
-	uint32_t vnet_len;	/* 14					   2 */
-	struct ethhdr eh;	/* 18					   6 */
+	struct tap_hdr taph;	/* 14					   2 */
 	struct ipv6hdr ip6h;	/* 32					  20 */
 	struct tcphdr th	/* 72 */ __attribute__ ((aligned(4))); /* 60 */ 
 	char opts[OPT_MSS_LEN + OPT_WS_LEN + 1];
@@ -1013,21 +1003,10 @@ void tcp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s,
 		struct tcp4_l2_buf_t *b4 = &tcp4_l2_buf[i];
 		struct tcp6_l2_buf_t *b6 = &tcp6_l2_buf[i];
 
-		if (eth_d) {
-			memcpy(b4->eh.h_dest, eth_d, ETH_ALEN);
-			memcpy(b6->eh.h_dest, eth_d, ETH_ALEN);
-
-			memcpy(b4f->eh.h_dest, eth_d, ETH_ALEN);
-			memcpy(b6f->eh.h_dest, eth_d, ETH_ALEN);
-		}
-
-		if (eth_s) {
-			memcpy(b4->eh.h_source, eth_s, ETH_ALEN);
-			memcpy(b6->eh.h_source, eth_s, ETH_ALEN);
-
-			memcpy(b4f->eh.h_source, eth_s, ETH_ALEN);
-			memcpy(b6f->eh.h_source, eth_s, ETH_ALEN);
-		}
+		tap_update_mac(&b4->taph, eth_d, eth_s);
+		tap_update_mac(&b6->taph, eth_d, eth_s);
+		tap_update_mac(&b4f->taph, eth_d, eth_s);
+		tap_update_mac(&b6f->taph, eth_d, eth_s);
 
 		if (ip_da) {
 			b4f->iph.daddr = b4->iph.daddr = ip_da->s_addr;
@@ -1051,15 +1030,16 @@ void tcp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s,
 
 /**
  * tcp_sock4_iov_init() - Initialise scatter-gather L2 buffers for IPv4 sockets
+ * @c:		Execution context
  */
-static void tcp_sock4_iov_init(void)
+static void tcp_sock4_iov_init(const struct ctx *c)
 {
 	struct iovec *iov;
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(tcp4_l2_buf); i++) {
 		tcp4_l2_buf[i] = (struct tcp4_l2_buf_t) {
-			.eh = L2_BUF_ETH_INIT(ETH_P_IP),
+			.taph = TAP_HDR_INIT(ETH_P_IP),
 			.iph = L2_BUF_IP4_INIT(IPPROTO_TCP),
 			.th = { .doff = sizeof(struct tcphdr) / 4, .ack = 1 }
 		};
@@ -1067,29 +1047,30 @@ static void tcp_sock4_iov_init(void)
 
 	for (i = 0; i < ARRAY_SIZE(tcp4_l2_flags_buf); i++) {
 		tcp4_l2_flags_buf[i] = (struct tcp4_l2_flags_buf_t) {
-			.eh = L2_BUF_ETH_INIT(ETH_P_IP),
+			.taph = TAP_HDR_INIT(ETH_P_IP),
 			.iph = L2_BUF_IP4_INIT(IPPROTO_TCP)
 		};
 	}
 
 	for (i = 0, iov = tcp4_l2_iov; i < TCP_FRAMES_MEM; i++, iov++)
-		iov->iov_base = &tcp4_l2_buf[i].vnet_len;
+		iov->iov_base = tap_iov_base(c, &tcp4_l2_buf[i].taph);
 
 	for (i = 0, iov = tcp4_l2_flags_iov; i < TCP_FRAMES_MEM; i++, iov++)
-		iov->iov_base = &tcp4_l2_flags_buf[i].vnet_len;
+		iov->iov_base = tap_iov_base(c, &tcp4_l2_flags_buf[i].taph);
 }
 
 /**
  * tcp_sock6_iov_init() - Initialise scatter-gather L2 buffers for IPv6 sockets
+ * @c:		Execution context
  */
-static void tcp_sock6_iov_init(void)
+static void tcp_sock6_iov_init(const struct ctx *c)
 {
 	struct iovec *iov;
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(tcp6_l2_buf); i++) {
 		tcp6_l2_buf[i] = (struct tcp6_l2_buf_t) {
-			.eh = L2_BUF_ETH_INIT(ETH_P_IPV6),
+			.taph = TAP_HDR_INIT(ETH_P_IPV6),
 			.ip6h = L2_BUF_IP6_INIT(IPPROTO_TCP),
 			.th = { .doff = sizeof(struct tcphdr) / 4, .ack = 1 }
 		};
@@ -1097,16 +1078,16 @@ static void tcp_sock6_iov_init(void)
 
 	for (i = 0; i < ARRAY_SIZE(tcp6_l2_flags_buf); i++) {
 		tcp6_l2_flags_buf[i] = (struct tcp6_l2_flags_buf_t) {
-			.eh = L2_BUF_ETH_INIT(ETH_P_IPV6),
+			.taph = TAP_HDR_INIT(ETH_P_IPV6),
 			.ip6h = L2_BUF_IP6_INIT(IPPROTO_TCP)
 		};
 	}
 
 	for (i = 0, iov = tcp6_l2_iov; i < TCP_FRAMES_MEM; i++, iov++)
-		iov->iov_base = &tcp6_l2_buf[i].vnet_len;
+		iov->iov_base = tap_iov_base(c, &tcp6_l2_buf[i].taph);
 
 	for (i = 0, iov = tcp6_l2_flags_iov; i < TCP_FRAMES_MEM; i++, iov++)
-		iov->iov_base = &tcp6_l2_flags_buf[i].vnet_len;
+		iov->iov_base = tap_iov_base(c, &tcp6_l2_flags_buf[i].taph);
 }
 
 /**
@@ -1493,10 +1474,7 @@ do {									\
 
 		tcp_update_check_tcp4(b);
 
-		tlen = ip_len + sizeof(struct ethhdr);
-		if (c->mode == MODE_PASST)
-			b->vnet_len = htonl(tlen);
-		tlen += sizeof(b->vnet_len);
+		tlen = tap_iov_len(c, &b->taph, ip_len);
 	} else {
 		struct tcp6_l2_buf_t *b = (struct tcp6_l2_buf_t *)p;
 
@@ -1519,10 +1497,7 @@ do {									\
 		b->ip6h.flow_lbl[1] = (conn->sock >> 8) & 0xff;
 		b->ip6h.flow_lbl[2] = (conn->sock >> 0) & 0xff;
 
-		tlen = ip_len + sizeof(struct ethhdr);
-		if (c->mode == MODE_PASST)
-			b->vnet_len = htonl(tlen);
-		tlen += sizeof(b->vnet_len);
+		tlen = tap_iov_len(c, &b->taph, ip_len);
 	}
 #undef SET_TCP_HEADER_COMMON_V4_V6
 
@@ -3117,10 +3092,10 @@ int tcp_init(struct ctx *c)
 		tcp_l2_mh[i] = (struct mmsghdr) { .msg_hdr.msg_iovlen = 1 };
 
 	if (c->ifi4)
-		tcp_sock4_iov_init();
+		tcp_sock4_iov_init(c);
 
 	if (c->ifi6)
-		tcp_sock6_iov_init();
+		tcp_sock6_iov_init(c);
 
 	memset(init_sock_pool4,		0xff,	sizeof(init_sock_pool4));
 	memset(init_sock_pool6,		0xff,	sizeof(init_sock_pool6));