From c604d823266eb2488c02af215c5d62d8d75cff91 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Mon, 10 Mar 2003 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 2003-03-10

---
 ip/arp.c         | 37 +++++++++++++++++++++----------------
 ip/ethermedium.c | 10 +++++-----
 ip/ip.h          |  6 +++---
 3 files changed, 29 insertions(+), 24 deletions(-)

diff --git a/ip/arp.c b/ip/arp.c
index 1353f32137dec98d793043af16bd13b5c7760f94..c4879e1f3ca0ac69e9e5110d94632aa15cdb30f8 100644
--- a/ip/arp.c
+++ b/ip/arp.c
@@ -75,10 +75,10 @@ newarp6(Arp *arp, uchar *ip, Ipifc *ifc, int addrxt)
 	/* find oldest entry */
 	e = &arp->cache[NCACHE];
 	a = arp->cache;
-	t = a->used;
+	t = a->utime;
 	for(f = a; f < e; f++){
-		if(f->used < t){
-			t = f->used;
+		if(f->utime < t){
+			t = f->utime;
 			a = f;
 		}
 	}
@@ -124,11 +124,11 @@ newarp6(Arp *arp, uchar *ip, Ipifc *ifc, int addrxt)
 	*l = a;
 
 	memmove(a->ip, ip, sizeof(a->ip));
-	a->used = NOW;
-	a->time = 0;
+	a->utime = NOW;
+	a->ctime = a->utime;
 	a->type = m;
 
-	a->rxtat = NOW + ReTransTimer;
+	a->rtime = NOW + ReTransTimer;
 	a->rxtsrem = MAX_MULTICAST_SOLICIT;
 	a->ifc = ifc;
 	a->ifcid = ifc->ifcid;
@@ -165,8 +165,8 @@ cleanarpent(Arp *arp, Arpent *a)
 {
 	Arpent *f, **l;
 
-	a->used = 0;
-	a->time = 0;
+	a->utime = 0;
+	a->ctime = 0;
 	a->type = 0;
 	a->state = 0;
 	
@@ -227,7 +227,7 @@ arpget(Arp *arp, Block *bp, int version, Ipifc *ifc, uchar *ip, uchar *mac)
 		a = newarp6(arp, ip, ifc, (version != V4));
 		a->state = AWAIT;
 	}
-	a->used = NOW;
+	a->utime = NOW;
 	if(a->state == AWAIT){
 		if(bp != nil){
 			if(a->hold)
@@ -241,6 +241,11 @@ arpget(Arp *arp, Block *bp, int version, Ipifc *ifc, uchar *ip, uchar *mac)
 	}
 
 	memmove(mac, a->mac, a->type->maclen);
+
+	/* remove old entries */
+	if(NOW - a->ctime > 15*60*1000)
+		cleanarpent(arp, a);
+
 	qunlock(arp);
 	return nil;
 }
@@ -280,7 +285,7 @@ arpresolve(Arp *arp, Arpent *a, Medium *type, uchar *mac)
 	memmove(a->mac, mac, type->maclen);
 	a->type = type;
 	a->state = AOK;
-	a->used = NOW;
+	a->utime = NOW;
 	bp = a->hold;
 	a->hold = nil;
 	qunlock(arp);
@@ -375,7 +380,8 @@ arpenter(Fs *fs, int version, uchar *ip, uchar *mac, int n, int refresh)
 					freeb(bp);
 				bp = next;
 			}
-			a->used = NOW;
+			a->utime = NOW;
+			a->ctime = a->utime;
 			return;
 		}
 	}
@@ -421,7 +427,7 @@ arpwrite(Fs *fs, char *s, int len)
 			memset(a->mac, 0, sizeof(a->mac));
 			a->hash = nil;
 			a->state = 0;
-			a->used = 0;
+			a->utime = 0;
 			while(a->hold != nil){
 				bp = a->hold->list;
 				freeblist(a->hold);
@@ -532,7 +538,7 @@ rxmitsols(Arp *arp)
 		nrxt = 0;
 		goto dodrops; 		//return nrxt;
 	}
-	nrxt = a->rxtat - NOW;
+	nrxt = a->rtime - NOW;
 	if(nrxt > 3*ReTransTimer/4) 
 		goto dodrops; 		//return nrxt;
 
@@ -589,14 +595,13 @@ rxmitsols(Arp *arp)
 	*l = a;
 	a->rxtsrem--;
 	a->nextrxt = nil;
-	a->time = NOW;
-	a->rxtat = NOW + ReTransTimer;
+	a->rtime = NOW + ReTransTimer;
 
 	a = arp->rxmt;
 	if(a==nil)
 		nrxt = 0;
 	else 
-		nrxt = a->rxtat - NOW;
+		nrxt = a->rtime - NOW;
 
 dodrops:
 	xp = arp->dropf;
diff --git a/ip/ethermedium.c b/ip/ethermedium.c
index 394babc8adbffa493cdbe1d5e1a603f2df753199..ad4676a9680590e2a7e7d8b65ffca95cc73e3fb6 100644
--- a/ip/ethermedium.c
+++ b/ip/ethermedium.c
@@ -453,7 +453,7 @@ sendarp(Ipifc *ifc, Arpent *a)
 	Etherrock *er = ifc->arg;
 
 	/* don't do anything if it's been less than a second since the last */
-	if(NOW - a->time < 1000){
+	if(NOW - a->ctime < 1000){
 		arprelease(er->f->arp, a);
 		return;
 	}
@@ -467,7 +467,7 @@ sendarp(Ipifc *ifc, Arpent *a)
 	}
 
 	/* try to keep it around for a second more */
-	a->time = NOW;
+	a->ctime = NOW;
 	arprelease(er->f->arp, a);
 
 	n = sizeof(Etherarp);
@@ -504,7 +504,7 @@ resolveaddr6(Ipifc *ifc, Arpent *a)
 	uchar ipsrc[IPaddrlen];
 
 	/* don't do anything if it's been less than a second since the last */
-	if(NOW - a->time < ReTransTimer){
+	if(NOW - a->ctime < ReTransTimer){
 		arprelease(er->f->arp, a);
 		return;
 	}
@@ -518,8 +518,8 @@ resolveaddr6(Ipifc *ifc, Arpent *a)
 	}
 
 	/* try to keep it around for a second more */
-	a->time = NOW;
-	a->rxtat = NOW + ReTransTimer;
+	a->ctime = NOW;
+	a->rtime = NOW + ReTransTimer;
 	if(a->rxtsrem <= 0) {
 		arprelease(er->f->arp, a);
 		return;
diff --git a/ip/ip.h b/ip/ip.h
index 158b139969ced89a9bd97bbe0d03b5a854b5adb9..acfe839185022678e51d5e3d06d8f56afa4e1f76 100644
--- a/ip/ip.h
+++ b/ip/ip.h
@@ -523,11 +523,11 @@ struct Arpent
 	Arpent*	hash;
 	Block*	hold;
 	Block*	last;
-	uint	time;
-	uint	used;
+	uint	ctime;			/* time entry was created or refreshed */
+	uint	utime;			/* time entry was last used */
 	uchar	state;
 	Arpent	*nextrxt;		/* re-transmit chain */
-	uint	rxtat;
+	uint	rtime;			/* time for next retransmission */
 	uchar	rxtsrem;
 	Ipifc	*ifc;
 	uchar	ifcid;			/* must match ifc->id */