From c887e6d2d9aee56ee7c9f2af4cec3a5efdcc4c72 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ilpo=20J=C3=A4rvinen?= Date: Sat, 14 Mar 2009 14:23:03 +0000 Subject: [PATCH] tcp: consolidate paws check MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Wow, it was quite tricky to merge that stream of negations but I think I finally got it right: check & replace_ts_recent: (s32)(rcv_tsval - ts_recent) >= 0 => 0 (s32)(ts_recent - rcv_tsval) <= 0 => 0 discard: (s32)(ts_recent - rcv_tsval) > TCP_PAWS_WINDOW => 1 (s32)(ts_recent - rcv_tsval) <= TCP_PAWS_WINDOW => 0 I toggled the return values of tcp_paws_check around since the old encoding added yet-another negation making tracking of truth-values really complicated. Signed-off-by: Ilpo Järvinen Signed-off-by: David S. Miller --- include/net/tcp.h | 18 ++++++++++++++---- net/ipv4/tcp_input.c | 11 +++++------ net/ipv4/tcp_minisocks.c | 4 ++-- 3 files changed, 21 insertions(+), 12 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index d74ac301e6b..255ca35bea0 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -997,11 +997,21 @@ static inline int tcp_fin_time(const struct sock *sk) return fin_timeout; } -static inline int tcp_paws_check(const struct tcp_options_received *rx_opt, int rst) +static inline int tcp_paws_check(const struct tcp_options_received *rx_opt, + int paws_win) { - if ((s32)(rx_opt->rcv_tsval - rx_opt->ts_recent) >= 0) - return 0; - if (get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS) + if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) + return 1; + if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) + return 1; + + return 0; +} + +static inline int tcp_paws_reject(const struct tcp_options_received *rx_opt, + int rst) +{ + if (tcp_paws_check(rx_opt, 0)) return 0; /* RST segments are not recommended to carry timestamp, diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index f527a16a7b3..b7d02c5dd6d 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3883,8 +3883,7 @@ static inline void tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq) * Not only, also it occurs for expired timestamps. */ - if ((s32)(tp->rx_opt.rcv_tsval - tp->rx_opt.ts_recent) >= 0 || - get_seconds() >= tp->rx_opt.ts_recent_stamp + TCP_PAWS_24DAYS) + if (tcp_paws_check(&tp->rx_opt, 0)) tcp_store_ts_recent(tp); } } @@ -3936,9 +3935,9 @@ static inline int tcp_paws_discard(const struct sock *sk, const struct sk_buff *skb) { const struct tcp_sock *tp = tcp_sk(sk); - return ((s32)(tp->rx_opt.ts_recent - tp->rx_opt.rcv_tsval) > TCP_PAWS_WINDOW && - get_seconds() < tp->rx_opt.ts_recent_stamp + TCP_PAWS_24DAYS && - !tcp_disordered_ack(sk, skb)); + + return !tcp_paws_check(&tp->rx_opt, TCP_PAWS_WINDOW) && + !tcp_disordered_ack(sk, skb); } /* Check segment sequence number for validity. @@ -5513,7 +5512,7 @@ discard: /* PAWS check. */ if (tp->rx_opt.ts_recent_stamp && tp->rx_opt.saw_tstamp && - tcp_paws_check(&tp->rx_opt, 0)) + tcp_paws_reject(&tp->rx_opt, 0)) goto discard_and_undo; if (th->syn) { diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 4b0df3e6b60..43bbba7926e 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -107,7 +107,7 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, if (tmp_opt.saw_tstamp) { tmp_opt.ts_recent = tcptw->tw_ts_recent; tmp_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp; - paws_reject = tcp_paws_check(&tmp_opt, th->rst); + paws_reject = tcp_paws_reject(&tmp_opt, th->rst); } } @@ -511,7 +511,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, * from another data. */ tmp_opt.ts_recent_stamp = get_seconds() - ((TCP_TIMEOUT_INIT/HZ)<retrans); - paws_reject = tcp_paws_check(&tmp_opt, th->rst); + paws_reject = tcp_paws_reject(&tmp_opt, th->rst); } } -- 2.41.1