From c3dd29c759676eaf1c670bceb2c59b7f9cfffa95 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sat, 27 May 2000 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 2000-05-27

---
 ip/udp.c         |  4 ++--
 mpc/clock.c      |  1 +
 port/devbridge.c | 21 +++++++++++++++++++--
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/ip/udp.c b/ip/udp.c
index ea3217654b193fa2320cb873dce3aa588177e813..4b6a22b2b10bec13ea3cc651a650b7e23835fc31 100644
--- a/ip/udp.c
+++ b/ip/udp.c
@@ -110,8 +110,8 @@ udpannounce(Conv *c, char** argv, int argc)
 static void
 udpcreate(Conv *c)
 {
-	c->rq = qopen(64*1024, 1, 0, 0);
-	c->wq = qopen(64*1024, 0, 0, 0);
+	c->rq = qopen(128*1024, 1, 0, 0);
+	c->wq = qopen(128*1024, 0, 0, 0);
 }
 
 static void
diff --git a/mpc/clock.c b/mpc/clock.c
index 0abdba1e93e7ef7d7396c18ac86d49e707d76660..32c8aedc57ed48f9831c4db603a847848963304f 100644
--- a/mpc/clock.c
+++ b/mpc/clock.c
@@ -52,6 +52,7 @@ microdelay(int l)
 	ulong i;
 
 	l *= m->delayloop;
+	l += 500;
 	l /= 1000;
 	if(l <= 0)
 		l = 1;
diff --git a/port/devbridge.c b/port/devbridge.c
index 71164e87b91bb3a85fe845ddaa5fe00fab2b5d5b..61e752737975c073efec667ab4a87b03abd84968 100644
--- a/port/devbridge.c
+++ b/port/devbridge.c
@@ -95,7 +95,9 @@ struct Bridge
 	Centry	cache[CacheSize];
 	ulong	hit;
 	ulong	miss;
-	ulong copy;
+	ulong	copy;
+	long	delay0;		// constant microsecond delay per packet
+	long	delayn;		// microsecond delay per byte
 	int tcpmss;		// modify tcpmss value
 
 	Log;
@@ -188,7 +190,7 @@ static void	etherread(void *a);
 static char	*cachedump(Bridge *b);
 static void	portfree(Port *port);
 static void	cacheflushport(Bridge *b, int port);
-static void etherwrite(Port *port, Block *bp);
+static void	etherwrite(Port *port, Block *bp);
 
 extern ulong	parseip(uchar*, char*);
 extern ushort	ipcsum(uchar *addr);
@@ -398,6 +400,11 @@ bridgewrite(Chan *c, void *a, long n, vlong off)
 			if(cb->nf != 2)
 				error("usage: clear option");
 			bridgeoption(b, cb->f[1], 0);
+		} else if(strcmp(arg0, "delay") == 0) {
+			if(cb->nf != 3)
+				error("usage: delay delay0 delayn");
+			b->delay0 = strtol(cb->f[1], nil, 10);
+			b->delayn = strtol(cb->f[2], nil, 10);
 		} else
 			error("unknown control request");
 		poperror();
@@ -972,6 +979,7 @@ etherread(void *a)
 	Block *bp, *bp2;
 	Etherpkt *ep;
 	Centry *ce;
+	long md;
 	
 	qlock(b);
 	port->readp = up;	/* hide identity under a rock for unbind */
@@ -1006,6 +1014,15 @@ if(0)print("devbridge: etherread: blocklen = %d\n", blocklen(bp));
 		if(b->tcpmss)
 			tcpmsshack(ep, BLEN(bp));
 
+		/*
+		 * delay packets to simulate a slow link
+		 */
+		if(b->delay0 || b->delayn){
+			md = b->delay0 + b->delayn * BLEN(bp);
+			if(md > 0)
+				microdelay(md);
+		}
+
 		if(ep->d[0] & 1) {
 			log(b, Logmcast, "mulitcast: port=%d src=%E dst=%E type=%#.4ux\n",
 				port->id, ep->s, ep->d, (ep->type[0]<<8)|ep->type[1] );