support for RFC3390 (Increasing TCP's Initial Window); ok deraadt, itojun

4 files changed, 21 insertions, 13 deletions

diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c
index d297e956bc4..2a2078b41c2 100644
--- a/sys/netinet/tcp_input.c
+++ b/sys/netinet/tcp_input.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tcp_input.c,v 1.148 2004/01/29 10:06:21 markus Exp $	*/
+/*	$OpenBSD: tcp_input.c,v 1.149 2004/01/29 11:55:28 markus Exp $	*/
 /*	$NetBSD: tcp_input.c,v 1.23 1996/02/13 23:43:44 christos Exp $	*/
 
 /*
@@ -1178,6 +1178,9 @@ after_listen:
 		TCP_TIMER_DISARM(tp, TCPT_REXMT);
 		tp->irs = th->th_seq;
 		tcp_mss(tp, opti.maxseg);
+		/* Reset initial window to 1 segment for retransmit */
+		if (tp->t_rxtshift > 0)
+			tp->snd_cwnd = tp->t_maxseg;
 		tcp_rcvseqinit(tp);
 		tp->t_flags |= TF_ACKNOW;
 #ifdef TCP_SACK
@@ -3067,6 +3070,9 @@ tcp_mss(tp, offer)
 			tp->snd_cwnd = ulmax((tp->snd_cwnd / tp->t_maxseg) *
 					     mss, mss);
 		}
+	} else if (tcp_do_rfc3390) {
+		/* increase initial window  */
+		tp->snd_cwnd = ulmin(4 * mss, ulmax(2 * mss, 4380));
 	} else
 		tp->snd_cwnd = mss;
 
@@ -3786,14 +3792,9 @@ syn_cache_get(src, dst, th, hlen, tlen, so, m)
 	tcp_mss(tp, sc->sc_peermaxseg);	 /* sets t_maxseg */
 	if (sc->sc_peermaxseg)
 		tcp_mss_update(tp);
-#if 0
-	/*
-	 * XXX
-	 * Initialize the initial congestion window.  If we
-	 * had to retransmit the SYN,ACK, we must initialize cwnd
-	 * to 1 segment (i.e. the Loss Window).
-	 */
-#endif
+	/* Reset initial window to 1 segment for retransmit */
+	if (sc->sc_rxtshift > 0)
+		tp->snd_cwnd = tp->t_maxseg;
 	tp->snd_wl1 = sc->sc_irs;
 	tp->rcv_up = sc->sc_irs + 1;
 
diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
index 6d308645b00..ddd9c25d1ab 100644
--- a/sys/netinet/tcp_subr.c
+++ b/sys/netinet/tcp_subr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tcp_subr.c,v 1.73 2004/01/09 12:22:30 markus Exp $	*/
+/*	$OpenBSD: tcp_subr.c,v 1.74 2004/01/29 11:55:28 markus Exp $	*/
 /*	$NetBSD: tcp_subr.c,v 1.22 1996/02/13 23:44:00 christos Exp $	*/
 
 /*
@@ -131,6 +131,7 @@ int	tcp_do_rfc1323 = TCP_DO_RFC1323;
 int	tcp_do_sack = TCP_DO_SACK;		/* RFC 2018 selective ACKs */
 int	tcp_ack_on_push = 0;	/* set to enable immediate ACK-on-PUSH */
 int	tcp_do_ecn = 0;		/* RFC3168 ECN enabled/disabled? */
+int	tcp_do_rfc3390 = 0;	/* RFC3390 Increasing TCP's Initial Window */
 
 u_int32_t	tcp_now;
 
diff --git a/sys/netinet/tcp_usrreq.c b/sys/netinet/tcp_usrreq.c
index c1a167a37a5..1b415e25294 100644
--- a/sys/netinet/tcp_usrreq.c
+++ b/sys/netinet/tcp_usrreq.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tcp_usrreq.c,v 1.75 2004/01/06 17:38:13 markus Exp $	*/
+/*	$OpenBSD: tcp_usrreq.c,v 1.76 2004/01/29 11:55:28 markus Exp $	*/
 /*	$NetBSD: tcp_usrreq.c,v 1.20 1996/02/13 23:44:16 christos Exp $	*/
 
 /*
@@ -931,6 +931,9 @@ tcp_sysctl(name, namelen, oldp, oldlenp, newp, newlen)
 	case TCPCTL_SYN_BUCKET_LIMIT:
 		return (sysctl_int(oldp, oldlenp, newp, newlen,
 		   &tcp_syn_bucket_limit));
+	case TCPCTL_RFC3390:
+		return (sysctl_int(oldp, oldlenp, newp, newlen,
+		    &tcp_do_rfc3390));
 	default:
 		return (ENOPROTOOPT);
 	}
diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h
index 22a448336eb..3a2eb273114 100644
--- a/sys/netinet/tcp_var.h
+++ b/sys/netinet/tcp_var.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tcp_var.h,v 1.55 2004/01/14 13:38:21 markus Exp $	*/
+/*	$OpenBSD: tcp_var.h,v 1.56 2004/01/29 11:55:28 markus Exp $	*/
 /*	$NetBSD: tcp_var.h,v 1.17 1996/02/13 23:44:24 christos Exp $	*/
 
 /*
@@ -434,7 +434,8 @@ struct	tcpstat {
 #define	TCPCTL_ECN	       14 /* RFC3168 ECN */
 #define	TCPCTL_SYN_CACHE_LIMIT 15 /* max size of comp. state engine */
 #define	TCPCTL_SYN_BUCKET_LIMIT	16 /* max size of hash bucket */
-#define	TCPCTL_MAXID	       17
+#define	TCPCTL_RFC3390	       17 /* enable/disable RFC3390 increased cwnd */
+#define	TCPCTL_MAXID	       18
 
 #define	TCPCTL_NAMES { \
 	{ 0, 0 }, \
@@ -454,6 +455,7 @@ struct	tcpstat {
 	{ "ecn", 	CTLTYPE_INT }, \
 	{ "syncachelimit", 	CTLTYPE_INT }, \
 	{ "synbucketlimit", 	CTLTYPE_INT }, \
+	{ "rfc3390", 	CTLTYPE_INT }, \
 }
 
 struct tcp_ident_mapping {
@@ -473,6 +475,7 @@ extern	int tcp_do_sack;	/* SACK enabled/disabled */
 extern	struct pool sackhl_pool;
 #endif
 extern	int tcp_do_ecn;		/* RFC3168 ECN enabled/disabled? */
+extern	int tcp_do_rfc3390;	/* RFC3390 Increasing TCP's Initial Window */
 
 extern	int tcp_syn_cache_limit; /* max entries for compressed state engine */
 extern	int tcp_syn_bucket_limit;/* max entries per hash bucket */