From 113bbbd8d2da61b50417a1dd06d8e7c19047e54b Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Wed, 25 Jul 2007 23:50:28 -0700 Subject: [PATCH] [TCP]: htcp - use measured rtt Change HTCP to use measured RTT rather than smooth RTT. Srtt is computed using the TCP receive timestamp options, so it is vulnerable to hostile receivers. To avoid any problems this might cause use the measured RTT instead. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/ipv4/tcp_htcp.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/net/ipv4/tcp_htcp.c b/net/ipv4/tcp_htcp.c index fa61663ace3b..b66556c0a5bd 100644 --- a/net/ipv4/tcp_htcp.c +++ b/net/ipv4/tcp_htcp.c @@ -76,12 +76,11 @@ static u32 htcp_cwnd_undo(struct sock *sk) return max(tp->snd_cwnd, (tp->snd_ssthresh << 7) / ca->beta); } -static inline void measure_rtt(struct sock *sk) +static inline void measure_rtt(struct sock *sk, u32 srtt) { const struct inet_connection_sock *icsk = inet_csk(sk); const struct tcp_sock *tp = tcp_sk(sk); struct htcp *ca = inet_csk_ca(sk); - u32 srtt = tp->srtt >> 3; /* keep track of minimum RTT seen so far, minRTT is zero at first */ if (ca->minRTT > srtt || !ca->minRTT) @@ -108,6 +107,9 @@ static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked, s32 rtt if (icsk->icsk_ca_state == TCP_CA_Open) ca->pkts_acked = pkts_acked; + if (rtt > 0) + measure_rtt(sk, usecs_to_jiffies(rtt)); + if (!use_bandwidth_switch) return; @@ -237,8 +239,6 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack, if (tp->snd_cwnd <= tp->snd_ssthresh) tcp_slow_start(tp); else { - measure_rtt(sk); - /* In dangerous area, increase slowly. * In theory this is tp->snd_cwnd += alpha / tp->snd_cwnd */ -- 2.30.2