diff options
Diffstat (limited to 'net/ipv4/tcp_input.c')
| -rw-r--r-- | net/ipv4/tcp_input.c | 29 |
1 files changed, 19 insertions, 10 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 24f1630b2afb..031cf72cd05c 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5378,8 +5378,8 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack, { struct tcp_sock *tp = tcp_sk(sk); struct sk_buff *data = tp->syn_data ? tcp_write_queue_head(sk) : NULL; - u16 mss = tp->rx_opt.mss_clamp; - bool syn_drop; + u16 mss = tp->rx_opt.mss_clamp, try_exp = 0; + bool syn_drop = false; if (mss == tp->rx_opt.user_mss) { struct tcp_options_received opt; @@ -5391,16 +5391,25 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack, mss = opt.mss_clamp; } - if (!tp->syn_fastopen) /* Ignore an unsolicited cookie */ + if (!tp->syn_fastopen) { + /* Ignore an unsolicited cookie */ cookie->len = -1; + } else if (tp->total_retrans) { + /* SYN timed out and the SYN-ACK neither has a cookie nor + * acknowledges data. Presumably the remote received only + * the retransmitted (regular) SYNs: either the original + * SYN-data or the corresponding SYN-ACK was dropped. + */ + syn_drop = (cookie->len < 0 && data); + } else if (cookie->len < 0 && !tp->syn_data) { + /* We requested a cookie but didn't get it. If we did not use + * the (old) exp opt format then try so next time (try_exp=1). + * Otherwise we go back to use the RFC7413 opt (try_exp=2). + */ + try_exp = tp->syn_fastopen_exp ? 2 : 1; + } - /* The SYN-ACK neither has cookie nor acknowledges the data. Presumably - * the remote receives only the retransmitted (regular) SYNs: either - * the original SYN-data or the corresponding SYN-ACK is lost. - */ - syn_drop = (cookie->len <= 0 && data && tp->total_retrans); - - tcp_fastopen_cache_set(sk, mss, cookie, syn_drop); + tcp_fastopen_cache_set(sk, mss, cookie, syn_drop, try_exp); if (data) { /* Retransmit unacked data in SYN */ tcp_for_write_queue_from(data, sk) { |