Split the magic to add a connected route for every new IPv4 address

added to an interface into two functions: one for route to prefix
and one for route to host.

This magic has been added to work around the behavior of rtinit() and
preserve the connected route to prefix when the first address of a
subnet is removed.  Since this "feature" has been present for point-
to-point interfaces too for more than 10 years, this diff does not
change anything in this regard, even if I'm not sure it makes sense.

Tested by benno@

1 files changed, 136 insertions, 72 deletions

diff --git a/sys/netinet/in.c b/sys/netinet/in.c
index c9cbc147345..a094d9a46ba 100644
--- a/sys/netinet/in.c
+++ b/sys/netinet/in.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: in.c,v 1.92 2014/03/14 12:08:18 krw Exp $	*/
+/*	$OpenBSD: in.c,v 1.93 2014/03/21 10:32:17 mpi Exp $	*/
 /*	$NetBSD: in.c,v 1.26 1996/02/13 23:41:39 christos Exp $	*/
 
 /*
@@ -94,8 +94,10 @@ int in_lifaddr_ioctl(struct socket *, u_long, caddr_t,
 	struct ifnet *);
 
 void in_purgeaddr(struct ifaddr *);
-int in_addprefix(struct in_ifaddr *, int);
+int in_addprefix(struct in_ifaddr *);
 int in_scrubprefix(struct in_ifaddr *);
+int in_addhost(struct in_ifaddr *);
+int in_scrubhost(struct in_ifaddr *);
 
 /* Return 1 if an internet address is for a directly connected host */
 int
@@ -609,7 +611,10 @@ in_lifaddr_ioctl(struct socket *so, u_long cmd, caddr_t data,
 void
 in_ifscrub(struct ifnet *ifp, struct in_ifaddr *ia)
 {
-	in_scrubprefix(ia);
+	if ((ifp->if_flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) == 0)
+		in_scrubprefix(ia);
+	else
+		in_scrubhost(ia);
 }
 
 /*
@@ -622,7 +627,7 @@ in_ifinit(struct ifnet *ifp, struct in_ifaddr *ia, struct sockaddr_in *sin,
 {
 	u_int32_t i = sin->sin_addr.s_addr;
 	struct sockaddr_in oldaddr;
-	int s = splnet(), flags = RTF_UP, error = 0;
+	int s = splnet(), error = 0;
 
 	if (newaddr)
 		TAILQ_INSERT_TAIL(&in_ifaddr, ia, ia_list);
@@ -682,13 +687,15 @@ in_ifinit(struct ifnet *ifp, struct in_ifaddr *ia, struct sockaddr_in *sin,
 		}
 	} else if (ifp->if_flags & IFF_LOOPBACK) {
 		ia->ia_dstaddr = ia->ia_addr;
-		flags |= RTF_HOST;
 	} else if (ifp->if_flags & IFF_POINTOPOINT) {
 		if (ia->ia_dstaddr.sin_family != AF_INET)
 			goto out;
-		flags |= RTF_HOST;
 	}
-	error = in_addprefix(ia, flags);
+
+	if ((ifp->if_flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) == 0)
+		error = in_addprefix(ia);
+	else
+		error = in_addhost(ia);
 
 	/*
 	 * If the interface supports multicast, join the "all hosts"
@@ -740,51 +747,118 @@ in_purgeaddr(struct ifaddr *ifa)
 	ifafree(&ia->ia_ifa);
 }
 
-#define rtinitflags(x) \
-	((((x)->ia_ifp->if_flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) != 0) \
-	    ? RTF_HOST : 0)
+int
+in_addhost(struct in_ifaddr *ia0)
+{
+	struct in_ifaddr *ia;
+	struct in_addr dst;
+	int error;
+
+	dst = ia0->ia_dstaddr.sin_addr;
+
+	/*
+	 * If an interface already have a route to the same
+	 * destination don't do anything.
+	 */
+	TAILQ_FOREACH(ia, &in_ifaddr, ia_list) {
+		if (ia->ia_ifp->if_rdomain != ia0->ia_ifp->if_rdomain)
+			continue;
+
+		if (dst.s_addr != ia->ia_dstaddr.sin_addr.s_addr)
+			continue;
+
+		if ((ia->ia_flags & IFA_ROUTE) == 0)
+			continue;
+
+		return (0);
+	}
+
+	error = rtinit(&ia0->ia_ifa, RTM_ADD, RTF_UP | RTF_HOST);
+	if (!error)
+		ia0->ia_flags |= IFA_ROUTE;
+
+	return (error);
+}
+
+int
+in_scrubhost(struct in_ifaddr *ia0)
+{
+	struct in_ifaddr *ia;
+	struct in_addr dst;
+	int error;
+
+	if ((ia0->ia_flags & IFA_ROUTE) == 0)
+		return (0);
+
+	dst = ia0->ia_dstaddr.sin_addr;
+
+	/*
+	 * Because we only add one route for a given destination at
+	 * a time, here we need to do some magic to move this route
+	 * to another interface if it has the same destination.
+	 */
+	TAILQ_FOREACH(ia, &in_ifaddr, ia_list) {
+		if (ia->ia_ifp->if_rdomain != ia0->ia_ifp->if_rdomain)
+			continue;
+
+		if (dst.s_addr != ia->ia_dstaddr.sin_addr.s_addr)
+			continue;
+
+		if ((ia->ia_flags & IFA_ROUTE) != 0)
+			continue;
+
+		rtinit(&ia0->ia_ifa, RTM_DELETE, RTF_HOST);
+		ia0->ia_flags &= ~IFA_ROUTE;
+		error = rtinit(&ia->ia_ifa, RTM_ADD, RTF_UP | RTF_HOST);
+		if (!error)
+			ia->ia_flags |= IFA_ROUTE;
+
+		return (error);
+	}
+
+	rtinit(&ia0->ia_ifa, RTM_DELETE, RTF_HOST);
+	ia0->ia_flags &= ~IFA_ROUTE;
+
+	return (0);
+}
 
 /*
  * add a route to prefix ("connected route" in cisco terminology).
  * does nothing if there's some interface address with the same prefix already.
  */
 int
-in_addprefix(struct in_ifaddr *target, int flags)
+in_addprefix(struct in_ifaddr *ia0)
 {
 	struct in_ifaddr *ia;
-	struct in_addr prefix, mask, p;
+	struct in_addr prefix, mask, p, m;
 	int error;
 
-	if ((flags & RTF_HOST) != 0)
-		prefix = target->ia_dstaddr.sin_addr;
-	else {
-		prefix = target->ia_addr.sin_addr;
-		mask = target->ia_sockmask.sin_addr;
-		prefix.s_addr &= mask.s_addr;
-	}
+	prefix = ia0->ia_addr.sin_addr;
+	mask = ia0->ia_sockmask.sin_addr;
+	prefix.s_addr &= mask.s_addr;
 
 	TAILQ_FOREACH(ia, &in_ifaddr, ia_list) {
-		if (ia->ia_ifp->if_rdomain != target->ia_ifp->if_rdomain)
+		if (ia->ia_ifp->if_rdomain != ia0->ia_ifp->if_rdomain)
 			continue;
-		if (rtinitflags(ia)) {
-			p = ia->ia_dstaddr.sin_addr;
-			if (prefix.s_addr != p.s_addr)
-				continue;
-		} else {
-			p = ia->ia_addr.sin_addr;
-			p.s_addr &= ia->ia_sockmask.sin_addr.s_addr;
-			if (prefix.s_addr != p.s_addr ||
-			    mask.s_addr != ia->ia_sockmask.sin_addr.s_addr)
-				continue;
-		}
+
+		if ((ia->ia_ifp->if_flags & (IFF_LOOPBACK | IFF_POINTOPOINT)))
+			continue;
+
 		if ((ia->ia_flags & IFA_ROUTE) == 0)
 			continue;
+
+		p = ia->ia_addr.sin_addr;
+		m = ia->ia_sockmask.sin_addr;
+		p.s_addr &= m.s_addr;
+
+		if (prefix.s_addr != p.s_addr || mask.s_addr != m.s_addr)
+			continue;
+
 #if NCARP > 0
 		/* move to a real interface instead of carp interface */
 		if (ia->ia_ifp->if_type == IFT_CARP &&
-		    target->ia_ifp->if_type != IFT_CARP) {
-			rtinit(&(ia->ia_ifa), (int)RTM_DELETE,
-			    rtinitflags(ia));
+		    ia0->ia_ifp->if_type != IFT_CARP) {
+			rtinit(&ia->ia_ifa, RTM_DELETE, 0);
 			ia->ia_flags &= ~IFA_ROUTE;
 			break;
 		}
@@ -799,9 +873,9 @@ in_addprefix(struct in_ifaddr *target, int flags)
 	/*
 	 * noone seem to have prefix route.  insert it.
 	 */
-	error = rtinit(&target->ia_ifa, (int)RTM_ADD, flags);
+	error = rtinit(&ia0->ia_ifa, RTM_ADD, RTF_UP);
 	if (!error)
-		target->ia_flags |= IFA_ROUTE;
+		ia0->ia_flags |= IFA_ROUTE;
 	return error;
 }
 
@@ -811,65 +885,55 @@ in_addprefix(struct in_ifaddr *target, int flags)
  * with the same prefix (otherwise we lose the route mistakenly).
  */
 int
-in_scrubprefix(struct in_ifaddr *target)
+in_scrubprefix(struct in_ifaddr *ia0)
 {
 	struct in_ifaddr *ia;
 	struct in_addr prefix, mask, p, m;
 	int error;
 
-	if ((target->ia_flags & IFA_ROUTE) == 0)
+	if ((ia0->ia_flags & IFA_ROUTE) == 0)
 		return 0;
 
-	if (rtinitflags(target)) {
-		prefix = target->ia_dstaddr.sin_addr;
-		mask.s_addr = INADDR_BROADCAST;
-	} else {
-		prefix = target->ia_addr.sin_addr;
-		mask = target->ia_sockmask.sin_addr;
-		prefix.s_addr &= mask.s_addr;
-	}
+	prefix = ia0->ia_addr.sin_addr;
+	mask = ia0->ia_sockmask.sin_addr;
+	prefix.s_addr &= mask.s_addr;
 
 	TAILQ_FOREACH(ia, &in_ifaddr, ia_list) {
-		if (rtinitflags(ia)) {
-			p = ia->ia_dstaddr.sin_addr;
-			m.s_addr = INADDR_BROADCAST;
-		} else {
-			p = ia->ia_addr.sin_addr;
-			m = ia->ia_sockmask.sin_addr;
-			p.s_addr &= m.s_addr;
-		}
+		if (ia->ia_ifp->if_rdomain != ia0->ia_ifp->if_rdomain)
+			continue;
 
-		if (ia->ia_ifp->if_rdomain != target->ia_ifp->if_rdomain)
+		if ((ia->ia_ifp->if_flags & (IFF_LOOPBACK | IFF_POINTOPOINT)))
 			continue;
-		if (prefix.s_addr != p.s_addr ||
-		    mask.s_addr != m.s_addr)
+
+		if ((ia->ia_flags & IFA_ROUTE) != 0)
 			continue;
+
+		p = ia->ia_addr.sin_addr;
+		m = ia->ia_sockmask.sin_addr;
+		p.s_addr &= m.s_addr;
+
+		if (prefix.s_addr != p.s_addr || mask.s_addr != m.s_addr)
+			continue;
+
 		/*
 		 * if we got a matching prefix route, move IFA_ROUTE to him
 		 */
-		if ((ia->ia_flags & IFA_ROUTE) == 0) {
-			rtinit(&(target->ia_ifa), (int)RTM_DELETE,
-			    rtinitflags(target));
-			target->ia_flags &= ~IFA_ROUTE;
-
-			error = rtinit(&ia->ia_ifa, (int)RTM_ADD,
-			    rtinitflags(ia) | RTF_UP);
-			if (error == 0)
-				ia->ia_flags |= IFA_ROUTE;
-			return error;
-		}
+		rtinit(&ia0->ia_ifa, RTM_DELETE, 0);
+		ia0->ia_flags &= ~IFA_ROUTE;
+		error = rtinit(&ia->ia_ifa, RTM_ADD, RTF_UP);
+		if (error == 0)
+			ia->ia_flags |= IFA_ROUTE;
+		return error;
 	}
 
 	/*
 	 * noone seem to have prefix route.  remove it.
 	 */
-	rtinit(&(target->ia_ifa), (int)RTM_DELETE, rtinitflags(target));
-	target->ia_flags &= ~IFA_ROUTE;
+	rtinit(&ia0->ia_ifa, RTM_DELETE, 0);
+	ia0->ia_flags &= ~IFA_ROUTE;
 	return 0;
 }
 
-#undef rtinitflags
-
 /*
  * Return 1 if the address might be a local broadcast address.
  */