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tcp: Simplify packet length calculation when preparing headers

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tcp_fill_headers[46]() compute the L3 packet length from the L4 packet
length, then their caller tcp_l2_buf_fill_headers() converts it back to the
L4 packet length.  We can just use the L4 length throughout.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>eewwee
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2024-05-01 16:53:50 +10:00 committed by Stefano Brivio
parent 5566386f5f
commit 68d1b0a152
1 changed files with 10 additions and 16 deletions
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26
tcp.c
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@ -1341,7 +1341,7 @@ static void tcp_fill_header(struct tcphdr *th,
* @check: Checksum, if already known * @check: Checksum, if already known
* @seq: Sequence number for this segment * @seq: Sequence number for this segment
* *
* Return: The total length of the IPv4 packet, host order * Return: The IPv4 payload length, host order
*/ */
static size_t tcp_fill_headers4(const struct ctx *c, static size_t tcp_fill_headers4(const struct ctx *c,
const struct tcp_tap_conn *conn, const struct tcp_tap_conn *conn,
@ -1367,7 +1367,7 @@ static size_t tcp_fill_headers4(const struct ctx *c,
tcp_update_check_tcp4(iph, th); tcp_update_check_tcp4(iph, th);
return l3len; return l4len;
} }
/** /**
@ -1380,7 +1380,7 @@ static size_t tcp_fill_headers4(const struct ctx *c,
* @check: Checksum, if already known * @check: Checksum, if already known
* @seq: Sequence number for this segment * @seq: Sequence number for this segment
* *
* Return: The total length of the IPv6 packet, host order * Return: The IPv6 payload length, host order
*/ */
static size_t tcp_fill_headers6(const struct ctx *c, static size_t tcp_fill_headers6(const struct ctx *c,
const struct tcp_tap_conn *conn, const struct tcp_tap_conn *conn,
@ -1388,7 +1388,6 @@ static size_t tcp_fill_headers6(const struct ctx *c,
size_t dlen, uint32_t seq) size_t dlen, uint32_t seq)
{ {
size_t l4len = dlen + sizeof(*th); size_t l4len = dlen + sizeof(*th);
size_t l3len = l4len + sizeof(*ip6h);
ip6h->payload_len = htons(l4len); ip6h->payload_len = htons(l4len);
ip6h->saddr = conn->faddr.a6; ip6h->saddr = conn->faddr.a6;
@ -1409,7 +1408,7 @@ static size_t tcp_fill_headers6(const struct ctx *c,
tcp_update_check_tcp6(ip6h, th); tcp_update_check_tcp6(ip6h, th);
return l3len; return l4len;
} }
/** /**
@ -1429,21 +1428,16 @@ static size_t tcp_l2_buf_fill_headers(const struct ctx *c,
const uint16_t *check, uint32_t seq) const uint16_t *check, uint32_t seq)
{ {
const struct in_addr *a4 = inany_v4(&conn->faddr); const struct in_addr *a4 = inany_v4(&conn->faddr);
size_t l3len, l4len;
if (a4) { if (a4) {
l3len = tcp_fill_headers4(c, conn, iov[TCP_IOV_IP].iov_base, return tcp_fill_headers4(c, conn, iov[TCP_IOV_IP].iov_base,
iov[TCP_IOV_PAYLOAD].iov_base, dlen, iov[TCP_IOV_PAYLOAD].iov_base, dlen,
check, seq); check, seq);
l4len = l3len - sizeof(struct iphdr);
} else {
l3len = tcp_fill_headers6(c, conn, iov[TCP_IOV_IP].iov_base,
iov[TCP_IOV_PAYLOAD].iov_base, dlen,
seq);
l4len = l3len - sizeof(struct ipv6hdr);
} }
return l4len; return tcp_fill_headers6(c, conn, iov[TCP_IOV_IP].iov_base,
iov[TCP_IOV_PAYLOAD].iov_base, dlen,
seq);
} }
/** /**