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tcp: Pass TCP header and payload separately to tcp_fill_headers[46]()

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At the moment these take separate pointers to the tap specific and IP
headers, but expect the TCP header and payload as a single tcp_payload_t.
As well as being slightly inconsistent, this involves some slightly iffy
pointer shenanigans when called on the flags path with a tcp_flags_t
instead of a tcp_payload_t.

More importantly, it's inconvenient for the upcoming vhost-user case, where
the TCP header and payload might not be contiguous.  Furthermore, the
payload itself might not be contiguous.

So, pass the TCP header as its own pointer, and the TCP payload as an IO
vector.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2024-11-27 14:54:07 +11:00 • committed by Stefano Brivio
commit 08ea3cc581
5 changed files with 65 additions and 75 deletions

22
tcp_buf.c
View file

@ -151,29 +151,27 @@ void tcp_payload_flush(const struct ctx *c)
* tcp_buf_fill_headers() - Fill 802.3, IP, TCP headers in pre-cooked buffers
* @conn: Connection pointer
* @iov: Pointer to an array of iovec of TCP pre-cooked buffers
* @dlen: TCP payload length
* @check: Checksum, if already known
* @seq: Sequence number for this segment
* @no_tcp_csum: Do not set TCP checksum
*/
static void tcp_l2_buf_fill_headers(const struct tcp_tap_conn *conn,
struct iovec *iov, size_t dlen,
const uint16_t *check, uint32_t seq,
bool no_tcp_csum)
struct iovec *iov, const uint16_t *check,
uint32_t seq, bool no_tcp_csum)
{
struct iov_tail tail = IOV_TAIL(&iov[TCP_IOV_PAYLOAD], 1, 0);
struct tcphdr *th = IOV_REMOVE_HEADER(&tail, struct tcphdr);
const struct flowside *tapside = TAPFLOW(conn);
const struct in_addr *a4 = inany_v4(&tapside->oaddr);
if (a4) {
tcp_fill_headers4(conn, iov[TCP_IOV_TAP].iov_base,
iov[TCP_IOV_IP].iov_base,
iov[TCP_IOV_PAYLOAD].iov_base, dlen,
check, seq, no_tcp_csum);
iov[TCP_IOV_IP].iov_base, th,
&tail, check, seq, no_tcp_csum);
} else {
tcp_fill_headers6(conn, iov[TCP_IOV_TAP].iov_base,
iov[TCP_IOV_IP].iov_base,
iov[TCP_IOV_PAYLOAD].iov_base, dlen,
seq, no_tcp_csum);
iov[TCP_IOV_IP].iov_base, th,
&tail, seq, no_tcp_csum);
}
}
@ -213,7 +211,7 @@ int tcp_buf_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags)
tcp_payload_used++;
l4len = optlen + sizeof(struct tcphdr);
iov[TCP_IOV_PAYLOAD].iov_len = l4len;
tcp_l2_buf_fill_headers(conn, iov, optlen, NULL, seq, false);
tcp_l2_buf_fill_headers(conn, iov, NULL, seq, false);
if (flags & DUP_ACK) {
struct iovec *dup_iov = tcp_l2_iov[tcp_payload_used++];
@ -270,7 +268,7 @@ static void tcp_data_to_tap(const struct ctx *c, struct tcp_tap_conn *conn,
payload->th.th_flags = 0;
payload->th.ack = 1;
iov[TCP_IOV_PAYLOAD].iov_len = dlen + sizeof(struct tcphdr);
tcp_l2_buf_fill_headers(conn, iov, dlen, check, seq, false);
tcp_l2_buf_fill_headers(conn, iov, check, seq, false);
if (++tcp_payload_used > TCP_FRAMES_MEM - 1)
tcp_payload_flush(c);
}