tcp_fill_headers() takes a pointer to a previously computed IPv4 header
checksum to avoid recalculating it when the payload length doesn't
change. A subsequent patch makes tcp_fill_headers() access ip4h via
with_header() which scopes it to a temporary variable, so a pointer to
ip4h->check would become dangling after the with_header() block.
Pass the checksum by value as an int instead, using -1 as the sentinel
to indicate that the checksum should be computed from scratch (replacing
the NULL pointer sentinel). As the checksum is a uint16_t, -1 cannot be
a valid checksum value in an int.
Signed-off-by: Laurent Vivier
---
tcp.c | 7 +++----
tcp_buf.c | 10 +++++-----
tcp_internal.h | 3 +--
tcp_vu.c | 12 ++++++------
4 files changed, 15 insertions(+), 17 deletions(-)
diff --git a/tcp.c b/tcp.c
index b14586249c4e..158a5be0327e 100644
--- a/tcp.c
+++ b/tcp.c
@@ -953,8 +953,7 @@ size_t tcp_fill_headers(const struct ctx *c, struct tcp_tap_conn *conn,
struct ethhdr *eh,
struct iphdr *ip4h, struct ipv6hdr *ip6h,
struct tcphdr *th, struct iov_tail *payload,
- const uint16_t *ip4_check, uint32_t seq,
- bool no_tcp_csum)
+ int ip4_check, uint32_t seq, bool no_tcp_csum)
{
const struct flowside *tapside = TAPFLOW(conn);
size_t l4len = iov_tail_size(payload) + sizeof(*th);
@@ -974,8 +973,8 @@ size_t tcp_fill_headers(const struct ctx *c, struct tcp_tap_conn *conn,
ip4h->saddr = src4->s_addr;
ip4h->daddr = dst4->s_addr;
- if (ip4_check)
- ip4h->check = *ip4_check;
+ if (ip4_check != -1)
+ ip4h->check = ip4_check;
else
ip4h->check = csum_ip4_header(l3len, IPPROTO_TCP,
*src4, *dst4);
diff --git a/tcp_buf.c b/tcp_buf.c
index 41965b107567..bc0f58dd7a5e 100644
--- a/tcp_buf.c
+++ b/tcp_buf.c
@@ -172,7 +172,7 @@ static void tcp_l2_buf_pad(struct iovec *iov)
*/
static void tcp_l2_buf_fill_headers(const struct ctx *c,
struct tcp_tap_conn *conn,
- struct iovec *iov, const uint16_t *check,
+ struct iovec *iov, int check,
uint32_t seq, bool no_tcp_csum)
{
struct iov_tail tail = IOV_TAIL(&iov[TCP_IOV_PAYLOAD], 1, 0);
@@ -233,7 +233,7 @@ int tcp_buf_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags)
if (flags & KEEPALIVE)
seq--;
- tcp_l2_buf_fill_headers(c, conn, iov, NULL, seq, false);
+ tcp_l2_buf_fill_headers(c, conn, iov, -1, seq, false);
tcp_l2_buf_pad(iov);
@@ -270,7 +270,7 @@ static void tcp_data_to_tap(const struct ctx *c, struct tcp_tap_conn *conn,
ssize_t dlen, int no_csum, uint32_t seq, bool push)
{
struct tcp_payload_t *payload;
- const uint16_t *check = NULL;
+ int check = -1;
struct iovec *iov;
conn->seq_to_tap = seq + dlen;
@@ -279,9 +279,9 @@ static void tcp_data_to_tap(const struct ctx *c, struct tcp_tap_conn *conn,
if (CONN_V4(conn)) {
if (no_csum) {
struct iovec *iov_prev = tcp_l2_iov[tcp_payload_used - 1];
- struct iphdr *iph = iov_prev[TCP_IOV_IP].iov_base;
+ const struct iphdr *iph = iov_prev[TCP_IOV_IP].iov_base;
- check = &iph->check;
+ check = iph->check;
}
iov[TCP_IOV_IP] = IOV_OF_LVALUE(tcp4_payload_ip[tcp_payload_used]);
} else if (CONN_V6(conn)) {
diff --git a/tcp_internal.h b/tcp_internal.h
index d9408852571f..bb7a6629839c 100644
--- a/tcp_internal.h
+++ b/tcp_internal.h
@@ -187,8 +187,7 @@ size_t tcp_fill_headers(const struct ctx *c, struct tcp_tap_conn *conn,
struct ethhdr *eh,
struct iphdr *ip4h, struct ipv6hdr *ip6h,
struct tcphdr *th, struct iov_tail *payload,
- const uint16_t *ip4_check, uint32_t seq,
- bool no_tcp_csum);
+ int ip4_check, uint32_t seq, bool no_tcp_csum);
int tcp_update_seqack_wnd(const struct ctx *c, struct tcp_tap_conn *conn,
bool force_seq, struct tcp_info_linux *tinfo);
diff --git a/tcp_vu.c b/tcp_vu.c
index 3001defb5467..a21ee3499aed 100644
--- a/tcp_vu.c
+++ b/tcp_vu.c
@@ -138,7 +138,7 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags)
seq--;
tcp_fill_headers(c, conn, eh, ip4h, ip6h, th, &payload,
- NULL, seq, !*c->pcap);
+ -1, seq, !*c->pcap);
if (*c->pcap)
pcap_iov(&flags_elem[0].in_sg[0], 1, VNET_HLEN);
@@ -283,7 +283,7 @@ static ssize_t tcp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq,
*/
static void tcp_vu_prepare(const struct ctx *c, struct tcp_tap_conn *conn,
struct iovec *iov, size_t iov_cnt,
- const uint16_t **check, bool no_tcp_csum, bool push)
+ int *check, bool no_tcp_csum, bool push)
{
const struct flowside *toside = TAPFLOW(conn);
bool v6 = !(inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr));
@@ -329,7 +329,7 @@ static void tcp_vu_prepare(const struct ctx *c, struct tcp_tap_conn *conn,
tcp_fill_headers(c, conn, eh, ip4h, ip6h, th, &payload,
*check, conn->seq_to_tap, no_tcp_csum);
if (ip4h)
- *check = &ip4h->check;
+ *check = ip4h->check;
}
/**
@@ -350,7 +350,7 @@ int tcp_vu_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn)
size_t hdrlen, fillsize;
int v6 = CONN_V6(conn);
uint32_t already_sent;
- const uint16_t *check;
+ int check;
if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) {
debug("Got packet, but RX virtqueue not usable yet");
@@ -437,7 +437,7 @@ int tcp_vu_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn)
*/
hdrlen = tcp_vu_hdrlen(v6);
- for (i = 0, previous_dlen = -1, check = NULL; i < head_cnt; i++) {
+ for (i = 0, previous_dlen = -1, check = -1; i < head_cnt; i++) {
struct iovec *iov = &elem[head[i]].in_sg[0];
int buf_cnt = head[i + 1] - head[i];
size_t frame_size = iov_size(iov, buf_cnt);
@@ -451,7 +451,7 @@ int tcp_vu_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn)
/* The IPv4 header checksum varies only with dlen */
if (previous_dlen != dlen)
- check = NULL;
+ check = -1;
previous_dlen = dlen;
tcp_vu_prepare(c, conn, iov, buf_cnt, &check, !*c->pcap, push);
--
2.53.0