From: Matthew Dillon <dillon@dragonflybsd.org>
Date: Thu, 16 Dec 2004 03:37:30 +0000 (+0000)
Subject: Correct a bug where incoming connections do not properly initialize the
X-Git-Tag: v2.0.1~9532
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/421de19e31318721c95ddb298c1c734933a2a615

Correct a bug where incoming connections do not properly initialize the
inflight bandwidth calculator.

Reorg the code a bit, removing random initialization elsewhere and putting
it all in one place.

Add an idle check and a pure-ack check.

Reported-by: Dan Nelson <dnelson@allantgroup.com>
---

diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
index 02555639da..e47300d370 100644
--- a/sys/netinet/tcp_subr.c
+++ b/sys/netinet/tcp_subr.c
@@ -82,7 +82,7 @@
  *
  *	@(#)tcp_subr.c	8.2 (Berkeley) 5/24/95
  * $FreeBSD: src/sys/netinet/tcp_subr.c,v 1.73.2.31 2003/01/24 05:11:34 sam Exp $
- * $DragonFly: src/sys/netinet/tcp_subr.c,v 1.40 2004/11/14 00:49:08 hsu Exp $
+ * $DragonFly: src/sys/netinet/tcp_subr.c,v 1.41 2004/12/16 03:37:30 dillon Exp $
  */
 
 #include "opt_compat.h"
@@ -692,7 +692,6 @@ tcp_newtcpcb(struct inpcb *inp)
 	tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 	tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 	tp->t_rcvtime = ticks;
-	tp->t_bw_rtttime = ticks;
 	/*
 	 * IPv4 TTL initialization is necessary for an IPv6 socket as well,
 	 * because the socket may be bound to an IPv6 wildcard address,
@@ -1834,6 +1833,7 @@ tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq)
 	u_long bw;
 	u_long bwnd;
 	int save_ticks;
+	int delta_ticks;
 
 	/*
 	 * If inflight_enable is disabled in the middle of a tcp connection,
@@ -1845,6 +1845,28 @@ tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq)
 		return;
 	}
 
+	/*
+	 * Validate the delta time.  If a connection is new or has been idle
+	 * a long time we have to reset the bandwidth calculator.
+	 */
+	save_ticks = ticks;
+	delta_ticks = save_ticks - tp->t_bw_rtttime;
+	if (tp->t_bw_rtttime == 0 || delta_ticks < 0 || delta_ticks > hz * 10) {
+		tp->t_bw_rtttime = ticks;
+		tp->t_bw_rtseq = ack_seq;
+		if (tp->snd_bandwidth == 0)
+			tp->snd_bandwidth = tcp_inflight_min;
+		return;
+	}
+	if (delta_ticks == 0)
+		return;
+
+	/*
+	 * Sanity check, plus ignore pure window update acks.
+	 */
+	if ((int)(ack_seq - tp->t_bw_rtseq) <= 0)
+		return;
+
 	/*
 	 * Figure out the bandwidth.  Due to the tick granularity this
 	 * is a very rough number and it MUST be averaged over a fairly
@@ -1852,20 +1874,10 @@ tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq)
 	 * that is not using all available bandwidth, but for now our
 	 * slop will ramp us up if this case occurs and the bandwidth later
 	 * increases.
-	 *
-	 * Note: if ticks rollover 'bw' may wind up negative.  We must
-	 * effectively reset t_bw_rtttime for this case.
 	 */
-	save_ticks = ticks;
-	if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1)
-		return;
-
-	bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 
-	    (save_ticks - tp->t_bw_rtttime);
+	bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / delta_ticks;
 	tp->t_bw_rtttime = save_ticks;
 	tp->t_bw_rtseq = ack_seq;
-	if (tp->t_bw_rtttime == 0 || (int)bw < 0)
-		return;
 	bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4;
 
 	tp->snd_bandwidth = bw;
diff --git a/sys/netinet/tcp_usrreq.c b/sys/netinet/tcp_usrreq.c
index e92ac2e770..5381cef64d 100644
--- a/sys/netinet/tcp_usrreq.c
+++ b/sys/netinet/tcp_usrreq.c
@@ -82,7 +82,7 @@
  *
  *	From: @(#)tcp_usrreq.c	8.2 (Berkeley) 1/3/94
  * $FreeBSD: src/sys/netinet/tcp_usrreq.c,v 1.51.2.17 2002/10/11 11:46:44 ume Exp $
- * $DragonFly: src/sys/netinet/tcp_usrreq.c,v 1.29 2004/12/08 23:59:01 hsu Exp $
+ * $DragonFly: src/sys/netinet/tcp_usrreq.c,v 1.30 2004/12/16 03:37:30 dillon Exp $
  */
 
 #include "opt_ipsec.h"
@@ -873,7 +873,6 @@ tcp_connect_oncpu(struct tcpcb *tp, struct sockaddr_in *sin,
 	tp->t_state = TCPS_SYN_SENT;
 	callout_reset(tp->tt_keep, tcp_keepinit, tcp_timer_keep, tp);
 	tp->iss = tcp_new_isn(tp);
-	tp->t_bw_rtseq = tp->iss;
 	tcp_sendseqinit(tp);
 
 	/*
@@ -1036,7 +1035,6 @@ tcp6_connect(struct tcpcb *tp, struct sockaddr *nam, struct thread *td)
 	tp->t_state = TCPS_SYN_SENT;
 	callout_reset(tp->tt_keep, tcp_keepinit, tcp_timer_keep, tp);
 	tp->iss = tcp_new_isn(tp);
-	tp->t_bw_rtseq = tp->iss;
 	tcp_sendseqinit(tp);
 
 	/*