shithub: riscv

Download patch

ref: 80f875fd9291b5357941c28cccd6b8aba373c181
parent: 57fc95de3c52ed71a6cd478ae495d2bcaeab7204
author: cinap_lenrek <[email protected]>
date: Sun Jan 7 18:39:29 EST 2024 

devip: no more wandering routes

Before, it was possible to add routes before
the interface existed.

The routes would look for their interface lazily
as the route was looked up, but this leads to
all kinds of hard to explain behaviour when
a interface goes away and the routes start
wandering to a different interface on their
own which they will stick to when a new
interface comes up that would match the route
better.

Instead, we have routes always associated
to their desination interface and remove
the routes when the interface gets unbound.

It is no longer possible to add routes for
interfaces that do not exist.

This is easier to reason about behaviour as
well as allows us to get rid of canrlock(ifc)
in findipifc().

All routes inside the routing tree are now
by definition up-to-date (as long as we
hold the routelock).

Callers of v4lookup()/v6lookup() still should
check if the ifcid of the interface still
matches the route once they have acquired
the interface lock.


--- a/sys/src/9/ip/arp.c
+++ b/sys/src/9/ip/arp.c
@@ -672,7 +672,7 @@
 		else
 			r = v6lookup(f, ((Ip6hdr*)bp->rp)->src, ((Ip6hdr*)bp->rp)->dst, &rh);
 		if(r != nil && (ifc = r->ifc) != nil && canrlock(ifc)){
-			if(!waserror()){
+			if(ifc->ifcid == r->ifcid && !waserror()){
 				if((bp->rp[0]&0xF0) == IP_VER4)
 					icmpnohost(f, ifc, bp, &rh);
 				else
--- a/sys/src/9/ip/ip.c
+++ b/sys/src/9/ip/ip.c
@@ -131,7 +131,7 @@
 		runlock(ifc);
 		nexterror();
 	}
-	if(ifc->m == nil)
+	if(ifc->m == nil || ifc->ifcid != r->ifcid)
 		goto raise;
 
 	medialen = ifc->maxtu - ifc->m->hsize;
--- a/sys/src/9/ip/ip.h
+++ b/sys/src/9/ip/ip.h
@@ -630,6 +630,7 @@
 extern Route*	v6source(Fs *f, uchar *a, uchar *s);
 extern long	routeread(Fs *f, char*, ulong, int);
 extern long	routewrite(Fs *f, Chan*, char*, int);
+extern void	flushrouteifc(Fs *f, Ipifc *ifc);
 extern void	routetype(int type, char p[8]);
 
 /*
--- a/sys/src/9/ip/ipifc.c
+++ b/sys/src/9/ip/ipifc.c
@@ -183,7 +183,7 @@
 		c->inuse++;
 
 	/* any ancillary structures (like routes) no longer pertain */
-	ifc->ifcid++;
+	flushrouteifc(c->p->f, ifc);
 
 	/* reopen all the queues closed by a previous unbind */
 	qreopen(c->rq);
@@ -201,6 +201,8 @@
 static char*
 ipifcunbindmedium(Ipifc *ifc, Medium *m)
 {
+	Conv *c = ifc->conv;
+
 	if(m == nil || m == &unboundmedium)
 		return Eunbound;
 
@@ -212,12 +214,12 @@
 	if(m->unbind != nil){
 		ifc->m = &unboundmedium;	/* fake until unbound */
 		wunlock(ifc);
-		qunlock(ifc->conv);
+		qunlock(c);
 		if(!waserror()){
 			(*m->unbind)(ifc);
 			poperror();
 		}
-		qlock(ifc->conv);
+		qlock(c);
 		wlock(ifc);
 	}
 
@@ -227,17 +229,17 @@
 	ifc->reassemble = 0;
 
 	/* close queues to stop queuing of packets */
-	qclose(ifc->conv->rq);
-	qclose(ifc->conv->wq);
-	qclose(ifc->conv->sq);
+	qclose(c->rq);
+	qclose(c->wq);
+	qclose(c->sq);
 
 	/* dissociate routes */
-	ifc->ifcid++;
+	flushrouteifc(c->p->f, ifc);
 	ifc->m = nil;
 	ifc->arg = nil;
 
 	if(m->unbindonclose == 0)
-		ifc->conv->inuse--;
+		c->inuse--;
 
 	return nil;
 }
@@ -1246,8 +1248,7 @@
 	xspec = 0;
 	for(cp = f->ipifc->conv; *cp != nil; cp++){
 		ifc = (Ipifc*)(*cp)->ptcl;
-		if(!canrlock(ifc))
-			continue;
+		rlock(ifc);
 		for(lifc = ifc->lifc; lifc != nil; lifc = lifc->next){
 			if(type & Runi){
 				if(ipcmp(remote, lifc->local) == 0)
@@ -1258,7 +1259,8 @@
 			}
 			maskip(remote, lifc->mask, gnet);
 			if(ipcmp(gnet, lifc->net) == 0){
-				spec = comprefixlen(remote, lifc->local, IPaddrlen);
+				spec = comprefixlen(remote, lifc->local, IPaddrlen)<<8;
+				spec += comprefixlen(local, lifc->local, IPaddrlen);
 				if(spec > xspec){
 					x = ifc;
 					xifcid = ifc->ifcid;
@@ -1268,7 +1270,8 @@
 		}
 		runlock(ifc);
 	}
-	if(x != nil && canrlock(x)){
+	if(x != nil){
+		rlock(x);
 		if(x->ifcid == xifcid)
 			return x;
 		runlock(x);
--- a/sys/src/9/ip/iproute.c
+++ b/sys/src/9/ip/iproute.c
@@ -170,7 +170,7 @@
 			return 0;
 	}
 
-	if(a->ifc != nil && b->ifc != nil && (a->ifc != b->ifc || a->ifcid != b->ifcid))
+	if(a->ifc != b->ifc)
 		return 0;
 
 	if(*a->tag != 0 && strncmp(a->tag, b->tag, sizeof(a->tag)) != 0)
@@ -358,28 +358,42 @@
 }
 
 static Route*
-looknodetag(Route *r, char *tag)
+looknodematch(Route *r, int (*match)(Route*, void*), void *arg)
 {
 	Route *x;
 
 	if(r == nil)
 		return nil;
-
-	if((x = looknodetag(r->mid, tag)) != nil)
+	if((x = looknodematch(r->mid, match, arg)) != nil)
 		return x;
-	if((x = looknodetag(r->left, tag)) != nil)
+	if((x = looknodematch(r->left, match, arg)) != nil)
 		return x;
-	if((x = looknodetag(r->right, tag)) != nil)
+	if((x = looknodematch(r->right, match, arg)) != nil)
 		return x;
+	if((*match)(r, arg))
+		return r;
+	return nil;
+}
 
-	if((r->type & Rifc) == 0){
-		if(tag == nil || strncmp(tag, r->tag, sizeof(r->tag)) == 0)
-			return r;
-	}
+static int
+matchtag(Route *r, void *arg)
+{
+	char *tag = (char*)arg;
 
-	return nil;
+	if(r->type & Rifc)
+		return 0;
+	return tag == nil || strncmp(tag, r->tag, sizeof(r->tag)) == 0;
 }
 
+static int
+matchifc(Route *r, void *arg)
+{
+	Ipifc *ifc = (Ipifc*)arg;
+
+	return r->ifc == ifc;
+}
+
+
 #define	V4H(a)	((a&0x07ffffff)>>(32-Lroot-5))
 #define	V6H(a)	(((a)[0]&0x80000000)>>(32-Lroot) | ((a)[(IPllen/2)-1]&(0xffff>>(16-Lroot))))
 
@@ -470,9 +484,13 @@
 	Route r;
 	int h;
 
+	assert(ifc != nil);
+
 	memset(&r, 0, sizeof(r));
 
 	r.type = type;
+	r.ifc = ifc;
+	r.ifcid = ifcid;
 
 	if(type & Rv4){
 		x = nhgetl(a+IPv4off);
@@ -506,11 +524,6 @@
 		memmove(r.v6.gate, gate, IPaddrlen);
 	}
 
-	if(ifc != nil){
-		r.ifc = ifc;
-		r.ifcid = ifcid;
-	}
-
 	if(tag != nil)
 		strncpy(r.tag, tag, sizeof(r.tag));
 
@@ -535,58 +548,35 @@
 	wunlock(&routelock);
 }
 
-/*
- * get the outgoing interface for route r,
- * interface is returned rlock'd.
- */
-static Ipifc*
-routefindipifc(Route *r, Fs *f)
+static void
+flushroutematch(Fs *f, int (*match)(Route*, void*), void *arg)
 {
-	uchar local[IPaddrlen], gate[IPaddrlen];
-	Ipifc *ifc;
-	int i;
+	Route r, *x;
+	int h;
 
-	ifc = r->ifc;
-	if(ifc != nil && canrlock(ifc)){
-		if(ifc->ifcid == r->ifcid)
-			return ifc;
-		runlock(ifc);
-		r->ifc = nil;
-	}
-
-	if(r->type & Rsrc) {
-		if(r->type & Rv4) {
-			hnputl(local+IPv4off, r->v4.source);
-			memmove(local, v4prefix, IPv4off);
-		} else {
-			for(i = 0; i < IPllen; i++)
-				hnputl(local+4*i, r->v6.source[i]);
+	wlock(&routelock);
+	for(h = 0; h < nelem(f->v4root); h++)
+		while((x = looknodematch(f->v4root[h], match, arg)) != nil){
+			memmove(&r, x, sizeof(RouteTree) + sizeof(V4route));
+			routedel(f, &r);
 		}
-	} else {
-		ipmove(local, IPnoaddr);
-	}
-
-	if(r->type & Rifc) {
-		if(r->type & Rv4) {
-			hnputl(gate+IPv4off, r->v4.address);
-			memmove(gate, v4prefix, IPv4off);
-		} else {
-			for(i = 0; i < IPllen; i++)
-				hnputl(gate+4*i, r->v6.address[i]);
+	for(h = 0; h < nelem(f->v6root); h++)
+		while((x = looknodematch(f->v6root[h], match, arg)) != nil){
+			memmove(&r, x, sizeof(RouteTree) + sizeof(V6route));
+			routedel(f, &r);
 		}
-	} else {
-		if(r->type & Rv4)
-			v4tov6(gate, r->v4.gate);
-		else
-			ipmove(gate, r->v6.gate);
-	}
+	wunlock(&routelock);
+}
 
-	ifc = findipifc(f, local, gate, r->type);
-	if(ifc != nil) {
-		r->ifc = ifc;
-		r->ifcid = ifc->ifcid;
-	}
-	return ifc;
+/*
+ * flushrouteifc:
+ *   remove all routes associated with ifc (wlock()'ed).
+ */
+void
+flushrouteifc(Fs *f, Ipifc *ifc)
+{
+	flushroutematch(f, matchifc, ifc);
+	ifc->ifcid++;	/* invalidate all routes */
 }
 
 /*
@@ -639,17 +629,9 @@
 		q = p;
 		p = p->mid;
 	}
-	if(q != nil){
-		ifc = routefindipifc(q, f);
-		if(ifc == nil)
-			q = nil;
-		else {
-			if(rh != nil){
-				rh->r = q;
-				rh->rgen = v4routegeneration;
-			}
-			runlock(ifc);
-		}
+	if(rh != nil){
+		rh->r = q;
+		rh->rgen = v4routegeneration;
 	}
 	runlock(&routelock);
 	return q;
@@ -736,17 +718,9 @@
 		p = p->mid;
 next:		;
 	}
-	if(q != nil){
-		ifc = routefindipifc(q, f);
-		if(ifc == nil)
-			q = nil;
-		else {
-			if(rh != nil){
-				rh->r = q;
-				rh->rgen = v6routegeneration;
-			}
-			runlock(ifc);
-		}
+	if(rh != nil){
+		rh->r = q;
+		rh->rgen = v6routegeneration;
 	}
 	runlock(&routelock);
 	return q;
@@ -770,8 +744,9 @@
 	Route *p, *q;
 	Ipifc *ifc;
 
-	q = nil;
 	la = nhgetl(a);
+again:
+	q = nil;
 	rlock(&routelock);
 	for(p = f->v4root[V4H(la)]; p != nil;){
 		if(la < p->v4.address){
@@ -782,11 +757,17 @@
 			p = p->right;
 			continue;
 		}
-
-		ifc = routefindipifc(p, f);
-		if(ifc == nil){
-			p = p->mid;
-			continue;
+		ifc = p->ifc;
+		if(!canrlock(ifc)){
+			int gen = v4routegeneration;
+			runlock(&routelock);
+			rlock(ifc);
+			rlock(&routelock);
+			if(v4routegeneration != gen){
+				runlock(&routelock);
+				runlock(ifc);
+				goto again;
+			}
 		}
 		splen = 0;
 		if(p->type & Rsrc){
@@ -818,9 +799,10 @@
 	Route *p, *q;
 	Ipifc *ifc;
 
-	q = nil;
 	for(h = 0; h < IPllen; h++)
 		la[h] = nhgetl(a+4*h);
+again:
+	q = nil;
 	rlock(&routelock);
 	for(p = f->v6root[V6H(la)]; p != nil;){
 		for(h = 0; h < IPllen; h++){
@@ -845,11 +827,17 @@
 			}
 			break;
 		}
-
-		ifc = routefindipifc(p, f);
-		if(ifc == nil){
-			p = p->mid;
-			continue;
+		ifc = p->ifc;
+		if(!canrlock(ifc)){
+			int gen = v6routegeneration;
+			runlock(&routelock);
+			rlock(ifc);
+			rlock(&routelock);
+			if(v6routegeneration != gen){
+				runlock(&routelock);
+				runlock(ifc);
+				goto again;
+			}
 		}
 		splen = 0;
 		if(p->type & Rsrc){
@@ -982,16 +970,13 @@
 seprintroute(char *p, char *e, Route *r)
 {
 	uchar addr[IPaddrlen], mask[IPaddrlen], src[IPaddrlen], smask[IPaddrlen], gate[IPaddrlen];
-	char type[8], ifbuf[4], *iname;
+	char type[8], ifbuf[4];
 
 	convroute(r, addr, mask, src, smask, gate);
 	routetype(r->type, type);
-	if(r->ifc != nil && r->ifcid == r->ifc->ifcid)
-		snprint(iname = ifbuf, sizeof ifbuf, "%d", r->ifc->conv->x);
-	else
-		iname = "-";
+	snprint(ifbuf, sizeof ifbuf, "%d", r->ifc->conv->x);
 	return seprint(p, e, "%-15I %-4M %-15I %-4s %4.4s %3s %-15I %-4M\n",
-		addr, mask, gate, type, r->tag, iname, src, smask);
+		addr, mask, gate, type, r->tag, ifbuf, src, smask);
 }
 
 typedef struct Routewalk Routewalk;
@@ -1074,6 +1059,7 @@
  *	7	add	addr	mask	gate			ifc	src	smask
  *	8	add	addr	mask	gate	type		ifc	src	smask
  *	9	add	addr	mask	gate	type	tag	ifc	src	smask
+ *
  *	3	del	addr	mask
  *	4	del	addr	mask	gate
  *	5	del	addr	mask					src	smask
@@ -1088,15 +1074,14 @@
 	uchar addr[IPaddrlen], mask[IPaddrlen];
 	uchar src[IPaddrlen], smask[IPaddrlen];
 	uchar gate[IPaddrlen];
+	char *ifcstr, *tag;
 	Ipifc *ifc;
 	uchar ifcid;
-	char *tag;
 	int type;
 
 	type = 0;
 	tag = nil;
-	ifc = nil;
-	ifcid = 0;
+	ifcstr = nil;
 	ipmove(gate, IPnoaddr);
 	ipmove(src, IPnoaddr);
 	ipmove(smask, IPnoaddr);
@@ -1120,13 +1105,9 @@
 	}
 
 	if(argc == 5 && strcmp(argv[0], "add") == 0)
-		ifc = findipifcstr(f, argv[4]);
-	if(argc > 6)
-		ifc = findipifcstr(f, argv[argc-3]);
-	if(ifc != nil){
-		ifcid = ifc->ifcid;
-		runlock(ifc);
-	}
+		ifcstr = argv[4];
+	else if(argc > 6)
+		ifcstr = argv[argc-3];
 
 	if(argc > 7 && (type = parseroutetype(argv[4])) < 0)
 		error(Ebadctl);
@@ -1148,6 +1129,15 @@
 			error(Ebadip);
 	}
 
+	if(ifcstr != nil)
+		ifc = findipifcstr(f, ifcstr);
+	else
+		ifc = findipifc(f, src, gate, type);
+	if(ifc == nil)
+		error("interface not found");
+	ifcid = ifc->ifcid;
+	runlock(ifc);
+
 	return mkroute(addr, mask, src, smask, gate, type, ifc, ifcid, tag);	
 }
 
@@ -1156,7 +1146,6 @@
 {
 	Cmdbuf *cb;
 	IPaux *a;
-	Route *x, r;
 
 	cb = parsecmd(p, n);
 	if(waserror()){
@@ -1166,25 +1155,11 @@
 	if(cb->nf < 1)
 		error("short control request");
 	if(strcmp(cb->f[0], "flush") == 0){
-		char *tag = cb->nf < 2 ? nil : cb->f[1];
-		int h;
-
-		wlock(&routelock);
-		for(h = 0; h < nelem(f->v4root); h++)
-			while((x = looknodetag(f->v4root[h], tag)) != nil){
-				memmove(&r, x, sizeof(RouteTree) + sizeof(V4route));
-				routedel(f, &r);
-			}
-		for(h = 0; h < nelem(f->v6root); h++)
-			while((x = looknodetag(f->v6root[h], tag)) != nil){
-				memmove(&r, x, sizeof(RouteTree) + sizeof(V6route));
-				routedel(f, &r);
-			}
-		wunlock(&routelock);
+		flushroutematch(f, matchtag, cb->nf < 2 ? nil : cb->f[1]);
 	} else if(strcmp(cb->f[0], "add") == 0
 		||strcmp(cb->f[0], "del") == 0
 		||strcmp(cb->f[0], "remove") == 0){
-		r = parseroute(f, cb->f, cb->nf);
+		Route r = parseroute(f, cb->f, cb->nf);
 		if(*r.tag == 0){
 			a = c->aux;
 			strncpy(r.tag, a->tag, sizeof(r.tag));
--- a/sys/src/9/ip/ipv6.c
+++ b/sys/src/9/ip/ipv6.c
@@ -85,7 +85,7 @@
 		nexterror();
 	}
 
-	if(ifc->m == nil)
+	if(ifc->m == nil || r->ifcid != ifc->ifcid)
 		goto raise;
 
 	medialen = ifc->maxtu - ifc->m->hsize;