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net-tcp: Fast Open client - receiving SYN-ACK

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On receiving the SYN-ACK after SYN-data, the client needs to
a) update the cached MSS and cookie (if included in SYN-ACK)
b) retransmit the data not yet acknowledged by the SYN-ACK in the final ACK of
   the handshake.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yuchung Cheng
2012-07-19 06:43:08 +00:00
committed by David S. Miller
parent 783237e8da
commit 8e4178c1c7
1 changed files with 35 additions and 5 deletions
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40
net/ipv4/tcp_input.c
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@@ -5646,6 +5646,34 @@ void tcp_finish_connect(struct sock *sk, struct sk_buff *skb)
} }
} }
static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack,
struct tcp_fastopen_cookie *cookie)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *data = tcp_write_queue_head(sk);
u16 mss = tp->rx_opt.mss_clamp;
if (mss == tp->rx_opt.user_mss) {
struct tcp_options_received opt;
const u8 *hash_location;
/* Get original SYNACK MSS value if user MSS sets mss_clamp */
tcp_clear_options(&opt);
opt.user_mss = opt.mss_clamp = 0;
tcp_parse_options(synack, &opt, &hash_location, 0, NULL);
mss = opt.mss_clamp;
}
tcp_fastopen_cache_set(sk, mss, cookie);
if (data) { /* Retransmit unacked data in SYN */
tcp_retransmit_skb(sk, data);
tcp_rearm_rto(sk);
return true;
}
return false;
}
static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
const struct tcphdr *th, unsigned int len) const struct tcphdr *th, unsigned int len)
{ {
@@ -5653,9 +5681,10 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
struct inet_connection_sock *icsk = inet_csk(sk); struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk); struct tcp_sock *tp = tcp_sk(sk);
struct tcp_cookie_values *cvp = tp->cookie_values; struct tcp_cookie_values *cvp = tp->cookie_values;
struct tcp_fastopen_cookie foc = { .len = -1 };
int saved_clamp = tp->rx_opt.mss_clamp; int saved_clamp = tp->rx_opt.mss_clamp;
tcp_parse_options(skb, &tp->rx_opt, &hash_location, 0, NULL); tcp_parse_options(skb, &tp->rx_opt, &hash_location, 0, &foc);
if (th->ack) { if (th->ack) {
/* rfc793: /* rfc793:
@@ -5665,11 +5694,9 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
* If SEG.ACK =< ISS, or SEG.ACK > SND.NXT, send * If SEG.ACK =< ISS, or SEG.ACK > SND.NXT, send
* a reset (unless the RST bit is set, if so drop * a reset (unless the RST bit is set, if so drop
* the segment and return)" * the segment and return)"
*
* We do not send data with SYN, so that RFC-correct
* test reduces to:
*/ */
if (TCP_SKB_CB(skb)->ack_seq != tp->snd_nxt) if (!after(TCP_SKB_CB(skb)->ack_seq, tp->snd_una) ||
after(TCP_SKB_CB(skb)->ack_seq, tp->snd_nxt))
goto reset_and_undo; goto reset_and_undo;
if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr && if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
@@ -5781,6 +5808,9 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
tcp_finish_connect(sk, skb); tcp_finish_connect(sk, skb);
if (tp->syn_fastopen && tcp_rcv_fastopen_synack(sk, skb, &foc))
return -1;
if (sk->sk_write_pending || if (sk->sk_write_pending ||
icsk->icsk_accept_queue.rskq_defer_accept || icsk->icsk_accept_queue.rskq_defer_accept ||
icsk->icsk_ack.pingpong) { icsk->icsk_ack.pingpong) {