[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_minisocks.c b/net/ipv4/tcp_minisocks.c
index 8245247..019c8c1 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -571,10 +571,8 @@
does sequence test, SYN is truncated, and thus we consider
it a bare ACK.
- If icsk->icsk_accept_queue.rskq_defer_accept, we silently drop this
- bare ACK. Otherwise, we create an established connection. Both
- ends (listening sockets) accept the new incoming connection and try
- to talk to each other. 8-)
+ Both ends (listening sockets) accept the new incoming
+ connection and try to talk to each other. 8-)
Note: This case is both harmless, and rare. Possibility is about the
same as us discovering intelligent life on another plant tomorrow.
@@ -642,13 +640,6 @@
if (!(flg & TCP_FLAG_ACK))
return NULL;
- /* If TCP_DEFER_ACCEPT is set, drop bare ACK. */
- if (inet_csk(sk)->icsk_accept_queue.rskq_defer_accept &&
- TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1) {
- inet_rsk(req)->acked = 1;
- return NULL;
- }
-
/* OK, ACK is valid, create big socket and
* feed this segment to it. It will repeat all
* the tests. THIS SEGMENT MUST MOVE SOCKET TO
@@ -687,7 +678,24 @@
inet_csk_reqsk_queue_unlink(sk, req, prev);
inet_csk_reqsk_queue_removed(sk, req);
- inet_csk_reqsk_queue_add(sk, req, child);
+ if (inet_csk(sk)->icsk_accept_queue.rskq_defer_accept &&
+ TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1) {
+
+ /* the accept queue handling is done is est recv slow
+ * path so lets make sure to start there
+ */
+ tcp_sk(child)->pred_flags = 0;
+ sock_hold(sk);
+ sock_hold(child);
+ tcp_sk(child)->defer_tcp_accept.listen_sk = sk;
+ tcp_sk(child)->defer_tcp_accept.request = req;
+
+ inet_csk_reset_keepalive_timer(child,
+ inet_csk(sk)->icsk_accept_queue.rskq_defer_accept * HZ);
+ } else {
+ inet_csk_reqsk_queue_add(sk, req, child);
+ }
+
return child;
listen_overflow: