Replace direct pointer arithmetic using vu_eth(), vu_ip(),
vu_payloadv4() and vu_payloadv6() with the iov_tail abstraction
to build Ethernet, IP and TCP headers in tcp_vu_prepare().
This removes the assumption that all headers reside in a single
contiguous iov entry.
Signed-off-by: Laurent Vivier
---
tcp_vu.c | 61 ++++++++++++++++++++++++++------------------------------
1 file changed, 28 insertions(+), 33 deletions(-)
diff --git a/tcp_vu.c b/tcp_vu.c
index c6206b7a689c..a39f6ea018e9 100644
--- a/tcp_vu.c
+++ b/tcp_vu.c
@@ -222,6 +222,7 @@ static ssize_t tcp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq,
/* reserve space for headers in iov */
iov = &elem[elem_cnt].in_sg[0];
assert(iov->iov_len >= hdrlen);
+
iov->iov_base = (char *)iov->iov_base + hdrlen;
iov->iov_len -= hdrlen;
head[(*head_cnt)++] = elem_cnt;
@@ -285,51 +286,45 @@ static void tcp_vu_prepare(const struct ctx *c, struct tcp_tap_conn *conn,
int *check, bool no_tcp_csum, bool push)
{
const struct flowside *toside = TAPFLOW(conn);
- bool v6 = !(inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr));
- size_t hdrlen = tcp_vu_hdrlen(v6);
- char *base = iov[0].iov_base;
- struct ipv6hdr *ip6h = NULL;
- struct iphdr *ip4h = NULL;
+ bool ipv4 = inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr);
struct iov_tail payload;
- struct tcphdr *th;
- struct ethhdr *eh;
-
- /* we guess the first iovec provided by the guest can embed
- * all the headers needed by L2 frame, including any padding
- */
- assert(iov[0].iov_len >= hdrlen);
-
- eh = vu_eth(base);
- memcpy(eh->h_dest, c->guest_mac, sizeof(eh->h_dest));
+ payload = IOV_TAIL(iov, iov_cnt, VNET_HLEN);
+ with_header(struct ethhdr, eh, &payload)
+ memcpy(eh->h_dest, c->guest_mac, sizeof(eh->h_dest));
+ IOV_DROP_HEADER(&payload, struct ethhdr);
/* initialize header */
- if (!v6) {
- eh->h_proto = htons(ETH_P_IP);
-
- ip4h = vu_ip(base);
- *ip4h = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_TCP);
- th = vu_payloadv4(base);
+ if (ipv4) {
+ with_header(struct iphdr, ip4h, &payload)
+ *ip4h = (struct iphdr)L2_BUF_IP4_INIT(IPPROTO_TCP);
+ IOV_DROP_HEADER(&payload, struct iphdr);
} else {
- eh->h_proto = htons(ETH_P_IPV6);
-
- ip6h = vu_ip(base);
- *ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_TCP);
-
- th = vu_payloadv6(base);
+ with_header(struct ipv6hdr, ip6h, &payload)
+ *ip6h = (struct ipv6hdr)L2_BUF_IP6_INIT(IPPROTO_TCP);
+ IOV_DROP_HEADER(&payload, struct ipv6hdr);
}
- memset(th, 0, sizeof(*th));
- th->doff = sizeof(*th) / 4;
- th->ack = 1;
- th->psh = push;
+ with_header(struct tcphdr, th, &payload) {
+ memset(th, 0, sizeof(*th));
+ th->doff = sizeof(*th) / 4;
+ th->ack = 1;
+ th->psh = push;
+ }
payload = IOV_TAIL(iov, iov_cnt, VNET_HLEN);
- tcp_fill_headers(c, conn, !v6, &payload, *check, conn->seq_to_tap,
+ tcp_fill_headers(c, conn, ipv4, &payload, *check, conn->seq_to_tap,
no_tcp_csum);
- if (ip4h)
+ if (ipv4) {
+ struct iphdr ip4h_storage;
+ const struct iphdr *ip4h;
+
+ IOV_DROP_HEADER(&payload, struct ethhdr);
+ ip4h = IOV_PEEK_HEADER(&payload, ip4h_storage);
+
*check = ip4h->check;
+ }
}
/**
--
2.53.0