[TCP]: TCP_DEFER_ACCEPT updates - process as established
Change TCP_DEFER_ACCEPT implementation so that it transitions a
connection to ESTABLISHED after handshake is complete instead of
leaving it in SYN-RECV until some data arrvies. Place connection in
accept queue when first data packet arrives from slow path.
Benefits:
- established connection is now reset if it never makes it
to the accept queue
- diagnostic state of established matches with the packet traces
showing completed handshake
- TCP_DEFER_ACCEPT timeouts are expressed in seconds and can now be
enforced with reasonable accuracy instead of rounding up to next
exponential back-off of syn-ack retry.
Signed-off-by: Patrick McManus <mcmanus@ducksong.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 9cf4464..6e46b4c 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4451,6 +4451,49 @@
}
}
+static int tcp_defer_accept_check(struct sock *sk)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+
+ if (tp->defer_tcp_accept.request) {
+ int queued_data = tp->rcv_nxt - tp->copied_seq;
+ int hasfin = !skb_queue_empty(&sk->sk_receive_queue) ?
+ tcp_hdr((struct sk_buff *)
+ sk->sk_receive_queue.prev)->fin : 0;
+
+ if (queued_data && hasfin)
+ queued_data--;
+
+ if (queued_data &&
+ tp->defer_tcp_accept.listen_sk->sk_state == TCP_LISTEN) {
+ if (sock_flag(sk, SOCK_KEEPOPEN)) {
+ inet_csk_reset_keepalive_timer(sk,
+ keepalive_time_when(tp));
+ } else {
+ inet_csk_delete_keepalive_timer(sk);
+ }
+
+ inet_csk_reqsk_queue_add(
+ tp->defer_tcp_accept.listen_sk,
+ tp->defer_tcp_accept.request,
+ sk);
+
+ tp->defer_tcp_accept.listen_sk->sk_data_ready(
+ tp->defer_tcp_accept.listen_sk, 0);
+
+ sock_put(tp->defer_tcp_accept.listen_sk);
+ sock_put(sk);
+ tp->defer_tcp_accept.listen_sk = NULL;
+ tp->defer_tcp_accept.request = NULL;
+ } else if (hasfin ||
+ tp->defer_tcp_accept.listen_sk->sk_state != TCP_LISTEN) {
+ tcp_reset(sk);
+ return -1;
+ }
+ }
+ return 0;
+}
+
static int tcp_copy_to_iovec(struct sock *sk, struct sk_buff *skb, int hlen)
{
struct tcp_sock *tp = tcp_sk(sk);
@@ -4811,6 +4854,9 @@
tcp_data_snd_check(sk);
tcp_ack_snd_check(sk);
+
+ if (tcp_defer_accept_check(sk))
+ return -1;
return 0;
csum_error: