From dc81b36ec040feee81bc100c5396a1f2e881f77d Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sat, 7 Mar 1998 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1998-03-07

---
 ip/ethermedium.c |  26 ++++------
 ip/il.c          |   1 +
 ip/ip.c          |  14 ++++-
 ip/ip.h          |   6 ++-
 ip/ipifc.c       | 132 +++++++++++++++--------------------------------
 ip/netlog.c      |   1 -
 ip/nullmedium.c  |   1 +
 ip/pktmedium.c   |   1 +
 8 files changed, 71 insertions(+), 111 deletions(-)

diff --git a/ip/ethermedium.c b/ip/ethermedium.c
index 741f40480f103b6887c6debce4bb6a4b052fa09f..76571a6c94f054d45284c5d3269b1e125ffbfed7 100644
--- a/ip/ethermedium.c
+++ b/ip/ethermedium.c
@@ -45,6 +45,7 @@ Medium ethermedium =
 	nil,			/* flushroute */
 	nil,			/* joinmulti */
 	nil,			/* leavemulti */
+	0,			/* don't unbind on last close */
 };
 
 typedef struct	Etherrock Etherrock;
@@ -205,7 +206,7 @@ etherunbind(Ipifc *ifc)
 }
 
 /*
- *  called by ipoput with a single block to write
+ *  called by ipoput with a single block to write with ifc rlock'd
  */
 static void
 etherbwrite(Ipifc *ifc, Block *bp, int version, uchar *ip)
@@ -215,17 +216,6 @@ etherbwrite(Ipifc *ifc, Block *bp, int version, uchar *ip)
 	uchar mac[6];
 	Etherrock *er = ifc->arg;
 
-	if(waserror()) {
-		print("etherbwrite failed\n");
-		ipifccheckout(ifc);
-		return;
-	}
-	if(ipifccheckin(ifc, &ethermedium) < 0){
-		freeb(bp);
-		poperror();
-		return;
-	}
-
 	/* get mac address of destination */
 	a = arpget(bp, version, &ethermedium, ip, mac);
 	if(a){
@@ -233,7 +223,7 @@ etherbwrite(Ipifc *ifc, Block *bp, int version, uchar *ip)
 		bp = multicastarp(a, mac);
 		if(bp == nil){
 			sendarp(ifc, a);
-			goto out;
+			return;
 		}
 	}
 
@@ -261,10 +251,6 @@ etherbwrite(Ipifc *ifc, Block *bp, int version, uchar *ip)
 
 	devtab[er->mchan->type]->bwrite(er->mchan, bp, 0);
 	ifc->out++;
-
-out:
-	ipifccheckout(ifc);
-	poperror();
 }
 
 /*
@@ -276,22 +262,28 @@ etherread(void *a)
 	Ipifc *ifc;
 	Block *bp;
 	Etherrock *er;
+	int locked = 0;
 
 	ifc = a;
 	er = ifc->arg;
 	er->readp = up;	/* hide identity under a rock for unbind */
 	if(waserror()){
+		if(locked)
+			runlock(ifc);
 		er->readp = 0;
 		pexit("hangup", 1);
 	}
 	for(;;){
 		bp = devtab[er->mchan->type]->bread(er->mchan, ifc->maxmtu, 0);
+		rlock(ifc);	locked = 1;	USED(locked);
 		ifc->in++;
 		bp->rp += ifc->m->hsize;
 		if(ifc->lifc == nil)
 			freeb(bp);
 		else
 			ipiput(ifc->lifc->local, bp);
+		runlock(ifc);	locked = 0;	USED(locked);
+
 	}
 }
 
diff --git a/ip/il.c b/ip/il.c
index e947a990aedd086a53f944748ec86f2229f8f299..4d8c58016fd785cffd8001f280711310ac5b0d20 100644
--- a/ip/il.c
+++ b/ip/il.c
@@ -347,6 +347,7 @@ ilxstats(char *buf, int len)
 		il.csumerr, il.hlenerr, il.lenerr, il.order, il.rexmit);
 	n += snprint(buf+n, len-n, " dupp %d dupb %d\n",
 		ilstats.dup, ilstats.dupb);
+	return n;
 }
 
 void
diff --git a/ip/ip.c b/ip/ip.c
index 2761a102eaa8223d32848283ceeb98cb5276c860..b8b1a5364328318dfdf0a3e1d014190c49af4d89 100644
--- a/ip/ip.c
+++ b/ip/ip.c
@@ -127,6 +127,14 @@ ipoput(Block *bp, int gating, int ttl)
 	}
 	ifc = r->ifc;
 
+	if(waserror()){
+		runlock(ifc);
+		nexterror();
+	}
+	rlock(ifc);
+	if(ifc->m == nil)
+		goto raise;
+
 	/* If we dont need to fragment just send it */
 	medialen = ifc->m->maxmtu - ifc->m->hsize;
 	if(len <= medialen) {
@@ -141,6 +149,8 @@ ipoput(Block *bp, int gating, int ttl)
 
 /*print("ipoput %V->%V via %V\n", eh->src, eh->dst, gate);*/
 		ifc->m->bwrite(ifc, bp, V4, gate);
+		runlock(ifc);
+		poperror();
 		return;
 	}
 
@@ -203,7 +213,7 @@ ipoput(Block *bp, int gating, int ttl)
 			chunk -= blklen;
 			if(xp->rp == xp->wp)
 				xp = xp->next;
-		} 
+		}
 
 		feh->cksum[0] = 0;
 		feh->cksum[1] = 0;
@@ -212,6 +222,8 @@ ipoput(Block *bp, int gating, int ttl)
 	}
 
 raise:
+	runlock(ifc);
+	poperror();
 	freeblist(bp);	
 }
 
diff --git a/ip/ip.h b/ip/ip.h
index 265926eb01bf5f54090933a8a5a17e5a7d59e864..d8f939af0cbfee24c445e541f0c211843c76a5c0 100644
--- a/ip/ip.h
+++ b/ip/ip.h
@@ -116,6 +116,8 @@ struct Medium
 	/* for routing multicast groups */
 	void	(*joinmulti)(Ipifc *ifc, uchar *a, uchar *ia, uchar **iap);
 	void	(*leavemulti)(Ipifc *ifc, uchar *a, uchar *ia);
+
+	int	unbindonclose;	/* if non-zero, unbind on last close */
 };
 
 /* logical interface associated with a physical one */
@@ -132,9 +134,9 @@ struct Iplifc
 /* binding twixt Ipself and Ipifc */
 struct Iplink
 {
-	Ipself	*local;
+	Ipself	*self;
 	Iplifc	*lifc;
-	Iplink	*locallink;	/* next link for this local address */
+	Iplink	*selflink;	/* next link for this local address */
 	Iplink	*lifclink;	/* next link for this ifc */
 	ulong	expire;
 	Iplink	*next;		/* free list */
diff --git a/ip/ipifc.c b/ip/ipifc.c
index 7a694dc1f2e51cc1bd318362ba5faeccff69075d..88a224b122cf14bf53694487bc76a428071a4125 100644
--- a/ip/ipifc.c
+++ b/ip/ipifc.c
@@ -23,6 +23,7 @@ extern	Fs	fs;
 Medium *media[] =
 {
 	&ethermedium,
+	&pktmedium,
 	&nullmedium,
 	0
 };
@@ -151,16 +152,18 @@ ipifcunbind(Ipifc *ifc)
 	}
 	wlock(ifc);
 
-	if(ipifcgrab(ifc) == 0);
-		goto out;
+	/* dissociate routes */
+	ifc->ifcid++;
+
+	/* disassociate device */
+	(*ifc->m->unbind)(ifc);
+	memset(ifc->dev, 0, sizeof(ifc->dev));
+	ifc->arg = nil;
 
 	/* hangup queues to stop queuing of packets */
 	qhangup(ifc->conv->rq, "unbind");
 	qhangup(ifc->conv->wq, "unbind");
 
-	/* dissociate routes */
-	ifc->ifcid++;
-
 	/* disassociate logical interfaces */
 	av[0] = "remove";
 	av[1] = ip;
@@ -172,14 +175,7 @@ ipifcunbind(Ipifc *ifc)
 		ipifcrem(ifc, av, 3, 0);
 	}
 
-	/* disassociate device */
-	(*ifc->m->unbind)(ifc);
-	memset(ifc->dev, 0, sizeof(ifc->dev));
-	ifc->arg = nil;
-	ifc->m = &nullmedium;
-	ifc->unbinding = 0;
-
-out:
+	ifc->m = nil;
 	wunlock(ifc);
 	poperror();
 	return nil;
@@ -223,7 +219,7 @@ ipifclocal(Conv *c, char *state, int n)
 	for(lifc = ifc->lifc; lifc; lifc = lifc->next){
 		m += snprint(state+m, n - m, "%-20.20I ->", lifc->local);
 		for(link = lifc->link; link; link = link->lifclink)
-			m += snprint(state+m, n - m, " %-20.20I", link->local->a);
+			m += snprint(state+m, n - m, " %-20.20I", link->self->a);
 		m += snprint(state+m, n - m, "\n");
 	}
 	runlock(ifc);
@@ -272,6 +268,8 @@ ipifccreate(Conv *c)
 	c->wq = qopen(QMAX, 0, 0, 0);
 	ifc = (Ipifc*)c->ptcl;
 	ifc->conv = c;
+	ifc->unbinding = 0;
+	ifc->m = nil;
 }
 
 /* 
@@ -281,10 +279,13 @@ ipifccreate(Conv *c)
 static void
 ipifcclose(Conv *c)
 {
-	/*
-	 *  nothing to do since conversation stays open
-	 *  till the device is unbound.
-	 */
+	Ipifc *ifc;
+	Medium *m;
+
+	ifc = (Ipifc*)c->ptcl;
+	m = ifc->m;
+	if(m != nil && m->unbindonclose)
+		ipifcunbind(ifc);
 	unlock(c);
 }
 
@@ -423,7 +424,7 @@ ipifcrem(Ipifc *ifc, char **argv, int argc, int dolock)
 
 	/* disassociate any addresses */
 	while(lifc->link)
-		remselfcache(ifc, lifc, lifc->link->local->a);
+		remselfcache(ifc, lifc, lifc->link->self->a);
 
 	/* remove the route for this logical interface */
 	if(isv4(ip))
@@ -456,6 +457,8 @@ ipifcaddroute(int vers, uchar *addr, uchar *mask, uchar *gate, int type)
 		if(*cp != nil) {
 			ifc = (Ipifc*)(*cp)->ptcl;
 			m = ifc->m;
+			if(m == nil)
+				continue;
 			if(m->addroute != nil)
 				m->addroute(ifc, vers, addr, mask, gate, type);
 		}
@@ -473,6 +476,8 @@ ipifcremroute(int vers, uchar *addr, uchar *mask)
 		if(*cp != nil) {
 			ifc = (Ipifc*)(*cp)->ptcl;
 			m = ifc->m;
+			if(m == nil)
+				continue;
 			if(m->remroute != nil)
 				m->remroute(ifc, vers, addr, mask);
 		}
@@ -603,7 +608,7 @@ addselfcache(Ipifc *ifc, Iplifc *lifc, uchar *a, int type)
 	}
 
 	/* look for a link for this lifc */
-	for(lp = p->link; lp; lp = lp->locallink)
+	for(lp = p->link; lp; lp = lp->selflink)
 		if(lp->lifc == lifc)
 			break;
 
@@ -612,8 +617,8 @@ addselfcache(Ipifc *ifc, Iplifc *lifc, uchar *a, int type)
 		lp = smalloc(sizeof(*lp));
 		lp->ref = 1;
 		lp->lifc = lifc;
-		lp->local = p;
-		lp->locallink = p->link;
+		lp->self = p;
+		lp->selflink = p->link;
 		p->link = lp;
 		lp->lifclink = lifc->link;
 		lifc->link = lp;
@@ -690,7 +695,7 @@ static void
 remselfcache(Ipifc *ifc, Iplifc *lifc, uchar *a)
 {
 	Ipself *p, **l;
-	Iplink *lp, *llp, **ill, **lll;
+	Iplink *link, **l_self, **l_lifc;
 
 	qlock(&selftab);
 
@@ -709,40 +714,40 @@ remselfcache(Ipifc *ifc, Iplifc *lifc, uchar *a)
 	 *  walk down links from an ifc looking for one
 	 *  that matches the selftab entry
 	 */
-	ill = &lifc->link;
-	for(lp = *ill; lp; lp = *ill){
-		if(lp->local == p)
+	l_lifc = &lifc->link;
+	for(link = *l_lifc; link; link = *l_lifc){
+		if(link->self == p)
 			break;
-		ill = &lp->lifclink;
+		l_lifc = &link->lifclink;
 	}
 
-	if(lp == nil)
+	if(link == nil)
 		goto out;
 
 	/*
 	 *  walk down the links from the selftab looking for
 	 *  the one we just found
 	 */
-	lll = &p->link;
-	for(llp = *lll; llp; llp = *lll){
-		if(llp == lp)
+	l_self = &p->link;
+	for(link = *l_self; link; link = *l_self){
+		if(link == *(l_lifc))
 			break;
-		lll = &lp->locallink;
+		l_self = &link->selflink;
 	}
 
-	if(llp == nil)
+	if(link == nil)
 		panic("remselfcache");
 
-	if(--(llp->ref) != 0)
+	if(--(link->ref) != 0)
 		goto out;
 
 	if((p->type & Rmulti) && ifc->m->remmulti != nil)
 		(*ifc->m->remmulti)(ifc, a, lifc->local);
 
 	/* ref == 0, remove from both chains and free the link */
-	*ill = lp->lifclink;
-	*lll = llp->locallink;
-	iplinkfree(lp);
+	*l_lifc = link->lifclink;
+	*l_self = link->selflink;
+	iplinkfree(link);
 
 	/* remove from routing table */
 	if(isv4(a))
@@ -1003,59 +1008,6 @@ ipismulticast(uchar *ip)
 	return 0;
 }
 
-/*
- *  used to allow on the fly unbinds, return -1 if interface unusable
- */
-int
-ipifccheckin(Ipifc *ifc, Medium *med)
-{
-	int rv;
-
-	lock(&ifc->idlock);
-	if(ifc->unbinding || ifc->m != med)
-		rv = -1;
-	else
-		rv = ++(ifc->ref);
-	if(ifc->ref < 0) panic("ipifccheckin");
-	unlock(&ifc->idlock);
-	return rv;
-}
-
-void
-ipifccheckout(Ipifc *ifc)
-{
-	lock(&ifc->idlock);
-	if(--(ifc->ref) == 0)
-	if(ifc->unbinding)
-		wakeup(&ifc->wait);
-	if(ifc->ref < 0) panic("ipifccheckin");
-	unlock(&ifc->idlock);
-}
-
-static int
-allout(void *x)
-{
-	Ipifc *ifc = x;
-
-	return ifc->ref == 0;
-}
-
-int
-ipifcgrab(Ipifc *ifc)
-{
-	lock(&ifc->idlock);
-	if(ifc->unbinding){
-		unlock(&ifc->idlock);
-		return 0;
-	}
-	ifc->unbinding = 1;		/* after this ref can only go down */
-	unlock(&ifc->idlock);
-
-	sleep(&ifc->wait, allout, ifc);
-
-	return 1;
-}
-
 /*
  *  add a multicast address to an interface, called with c->car locked
  */
diff --git a/ip/netlog.c b/ip/netlog.c
index 41f6605c23eb9672265ea847b8792daf7b28448a..50f36f917c725a705a6baf955f73bfc5ea722228 100644
--- a/ip/netlog.c
+++ b/ip/netlog.c
@@ -152,7 +152,6 @@ netlogctl(char* s, int len)
 	int i, n, set;
 	Logflag *f;
 	char *fields[10], *p, buf[256];
-	uchar addr[IPaddrlen];
 
 	if(len == 0)
 		return Ebadnetctl;
diff --git a/ip/nullmedium.c b/ip/nullmedium.c
index c4acd3ff5c95f3909c7622db434c5200d235952b..b848d29fbe94574024fcb2ece8c55d427cdc8399 100644
--- a/ip/nullmedium.c
+++ b/ip/nullmedium.c
@@ -43,4 +43,5 @@ Medium nullmedium =
 	nil,		/* flushroute */
 	nil,		/* joinmulti */
 	nil,		/* leave multi */
+	0,		/* don't unbind on last close */
 };
diff --git a/ip/pktmedium.c b/ip/pktmedium.c
index 6a2500bdb7fa4f9dfdb2e0b555ee5fa3a3db9fd3..8c1b6c50675d22889f57681a3feefa7408e8b19f 100644
--- a/ip/pktmedium.c
+++ b/ip/pktmedium.c
@@ -32,6 +32,7 @@ Medium pktmedium =
 	nil,		/* flushroute */
 	nil,		/* joinmulti */
 	nil,		/* leave multi */
+	1,		/* unbind on last close */
 };
 
 /*