route.generic

VRRP双机热备份协议源吗

+			return -EINVAL;
+	}
+
+	/* INTERFACE */
+	/* Store the interface information to allow users to get it via
+	 * [SOL_IP, IP_PKTINFO] conrol message for locally seen packets
+	 * (including broadcast and multicast ones).  --SAW */
+	rth->rt_iif	= key->oif ? : dev_out->ifindex;
+	/* Set output device */
+	rth->u.dst.dev	= dev_out;
+	dev_hold(dev_out);
+
+	/* Set GATEWAY */
+	rth->rt_gateway = daddr;
+	/* if res->fi != NULL set the real gateway */
+	rt_set_nexthop(rth, res, 0);
+
+	rth->rt_flags = flags;
+
+	hash = rt_hash_code(key->dst, key->src^(key->oif<<5), key->tos);
+	return rt_intern_hash(hash, rth, rp);
+}
+
 /*
  * Major route resolver routine.
  */
-
 int ip_route_output_slow(struct rtable **rp, u32 daddr, u32 saddr, u32 tos, int oif)
 {
 	struct rt_key key;
 	struct fib_result res;
-	unsigned flags = 0;
-	struct rtable *rth;
 	struct net_device *dev_out = NULL;
-	unsigned hash;
-	int free_res = 0;
 	int err;
 
-	tos &= IPTOS_TOS_MASK|RTO_ONLINK;
 	key.dst = daddr;
 	key.src = saddr;
 	key.tos = tos&IPTOS_TOS_MASK;
@@ -1619,252 +1792,100 @@
 	res.r = NULL;
 #endif
 
-	if (saddr) {
-		if (MULTICAST(saddr) || BADCLASS(saddr) || ZERONET(saddr))
-			return -EINVAL;
-
-		/* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
-		dev_out = ip_dev_find(saddr);
-		if (dev_out == NULL)
-			return -EINVAL;
-
-		/* I removed check for oif == dev_out->oif here.
-		   It was wrong by three reasons:
-		   1. ip_dev_find(saddr) can return wrong iface, if saddr is
-		      assigned to multiple interfaces.
-		   2. Moreover, we are allowed to send packets with saddr
-		      of another iface. --ANK
-		 */
-
-		if (oif == 0 &&
-			(MULTICAST(daddr) || daddr == 0xFFFFFFFF)) {
-			/* Special hack: user can direct multicasts
-			   and limited broadcast via necessary interface
-			   without fiddling with IP_MULTICAST_IF or IP_PKTINFO.
-			   This hack is not just for fun, it allows
-			   vic,vat and friends to work.
-			   They bind socket to loopback, set ttl to zero
-			   and expect that it will work.
-			   From the viewpoint of routing cache they are broken,
-			   because we are not allowed to build multicast path
-			   with loopback source addr (look, routing cache
-			   cannot know, that ttl is zero, so that packet
-			   will not leave this host and route is valid).
-			   Luckily, this hack is good workaround.
-			 */
-
-			key.oif = dev_out->ifindex;
-			goto make_route;
-		}
-		if (dev_out)
-			dev_put(dev_out);
-		dev_out = NULL;
-	}
-	if (oif) {
-		dev_out = dev_get_by_index(oif);
-		if (dev_out == NULL)
-			return -ENODEV;
-		if (__in_dev_get(dev_out) == NULL) {
-			dev_put(dev_out);
-			return -ENODEV;	/* Wrong error code */
-		}
-
-		if (LOCAL_MCAST(daddr) || daddr == 0xFFFFFFFF) {
-			if (!key.src)
-				key.src = inet_select_addr(dev_out, 0, RT_SCOPE_LINK);
-			goto make_route;
-		}
-		if (!key.src) {
-			if (MULTICAST(daddr))
-				key.src = inet_select_addr(dev_out, 0, key.scope);
-			else if (!daddr)
-				key.src = inet_select_addr(dev_out, 0, RT_SCOPE_HOST);
-		}
-	}
+	if (!daddr)
+		goto dest_insanity;
 
-	if (!key.dst) {
-		key.dst = key.src;
-		if (!key.dst)
-			key.dst = key.src = htonl(INADDR_LOOPBACK);
-		if (dev_out)
-			dev_put(dev_out);
-		dev_out = &loopback_dev;
+	err = fib_lookup(&key, &res);
+	if (!err) {
+		dev_out = FIB_RES_DEV(res);
 		dev_hold(dev_out);
-		key.oif = loopback_dev.ifindex;
-		res.type = RTN_LOCAL;
-		flags |= RTCF_LOCAL;
-		goto make_route;
-	}
-
-	if (fib_lookup(&key, &res)) {
-		res.fi = NULL;
-		if (oif) {
-			/* Apparently, routing tables are wrong. Assume,
-			   that the destination is on link.
-
-			   WHY? DW.
-			   Because we are allowed to send to iface
-			   even if it has NO routes and NO assigned
-			   addresses. When oif is specified, routing
-			   tables are looked up with only one purpose:
-			   to catch if destination is gatewayed, rather than
-			   direct. Moreover, if MSG_DONTROUTE is set,
-			   we send packet, ignoring both routing tables
-			   and ifaddr state. --ANK
-
-
-			   We could make it even if oif is unknown,
-			   likely IPv6, but we do not.
+		if (saddr) {
+			/* Verify user supplied source address */
+			err = outrt_check_src(saddr, daddr, tos, dev_out);
+		} else {
+			/* Obtain path source from routing table */
+			saddr = FIB_RES_PREFSRC(res);
+			/* We don't verify source address obtained from routing
+			 * table.  It's a task of administrators to keep it
+			 * sane.
 			 */
-
-			if (key.src == 0)
-				key.src = inet_select_addr(dev_out, 0, RT_SCOPE_LINK);
-			res.type = RTN_UNICAST;
-			goto make_route;
 		}
-		if (dev_out)
-			dev_put(dev_out);
-		return -ENETUNREACH;
-	}
-	free_res = 1;
-
-	if (res.type == RTN_NAT)
-		goto e_inval;
-
-	if (res.type == RTN_LOCAL) {
-		if (!key.src)
-			key.src = key.dst;
-		if (dev_out)
-			dev_put(dev_out);
-		dev_out = &loopback_dev;
-		dev_hold(dev_out);
-		key.oif = dev_out->ifindex;
-		if (res.fi)
-			fib_info_put(res.fi);
-		res.fi = NULL;
-		flags |= RTCF_LOCAL;
-		goto make_route;
-	}
-
-#ifdef CONFIG_IP_ROUTE_MULTIPATH
-	if (res.fi->fib_nhs > 1 && key.oif == 0)
-		fib_select_multipath(&key, &res);
-	else
-#endif
-	if (res.prefixlen==0 && res.type == RTN_UNICAST && key.oif == 0)
-		fib_select_default(&key, &res);
-
-	if (!key.src)
-		key.src = FIB_RES_PREFSRC(res);
-
-	if (dev_out)
-		dev_put(dev_out);
-	dev_out = FIB_RES_DEV(res);
-	dev_hold(dev_out);
-	key.oif = dev_out->ifindex;
-
-make_route:
-	if (LOOPBACK(key.src) && !(dev_out->flags&IFF_LOOPBACK))
-		goto e_inval;
-
-	if (key.dst == 0xFFFFFFFF)
-		res.type = RTN_BROADCAST;
-	else if (MULTICAST(key.dst))
-		res.type = RTN_MULTICAST;
-	else if (BADCLASS(key.dst) || ZERONET(key.dst))
-		goto e_inval;
+		if (!err)
+			err = outrt_make_route(rp, &key, daddr, saddr,
+					dev_out, &res);
+		fib_res_put(&res);
+		/* The usual code path ends here */
 
-	if (dev_out->flags&IFF_LOOPBACK)
-		flags |= RTCF_LOCAL;
+	} else if (err == -ENETUNREACH) {
 
-	if (res.type == RTN_BROADCAST) {
-		flags |= RTCF_BROADCAST|RTCF_LOCAL;
-		if (res.fi) {
-			fib_info_put(res.fi);
-			res.fi = NULL;
-		}
-	} else if (res.type == RTN_MULTICAST) {
-		flags |= RTCF_MULTICAST|RTCF_LOCAL;
-		read_lock(&inetdev_lock);
-		if (!__in_dev_get(dev_out) || !ip_check_mc(__in_dev_get(dev_out), daddr))
-			flags &= ~RTCF_LOCAL;
-		read_unlock(&inetdev_lock);
-		/* If multicast route do not exist use
-		   default one, but do not gateway in this case.
-		   Yes, it is hack.
+		/* Just return if the access is prohibited etc.
+		   If the routing table doesn't have both an appropriate route
+		   and a default assume that the destination is on link.  --SAW
+
+		   WHY? DW.
+		   Because we are allowed to send to iface
+		   even if it has NO routes and NO assigned
+		   addresses. When oif is specified, routing
+		   tables are looked up with only one purpose:
+		   to catch if destination is gatewayed, rather than
+		   direct. Moreover, if MSG_DONTROUTE is set,
+		   we send packet, ignoring both routing tables
+		   and ifaddr state. --ANK
+
+		   We could make it even if oif is unknown,
+		   likely IPv6, but we do not.
+
+		   The above statements aren't exactly correct.
+		   Routing tables contain a lot of useful information (like
+		   preferred source, for instance).  But the general idea is
+		   right.  --SAW
 		 */
-		if (res.fi && res.prefixlen < 4) {
-			fib_info_put(res.fi);
-			res.fi = NULL;
-		}
-	}
-
-	rth = dst_alloc(&ipv4_dst_ops);
-	if (!rth)
-		goto e_nobufs;
-
-	atomic_set(&rth->u.dst.__refcnt, 1);
-	rth->u.dst.flags= DST_HOST;
-	rth->key.dst	= daddr;
-	rth->key.tos	= tos;
-	rth->key.src	= saddr;
-	rth->key.iif	= 0;
-	rth->key.oif	= oif;
-	rth->rt_dst	= key.dst;
-	rth->rt_src	= key.src;
-#ifdef CONFIG_IP_ROUTE_NAT
-	rth->rt_dst_map	= key.dst;
-	rth->rt_src_map	= key.src;
-#endif
-	rth->rt_iif	= oif ? : dev_out->ifindex;
-	rth->u.dst.dev	= dev_out;
-	dev_hold(dev_out);
-	rth->rt_gateway = key.dst;
-	rth->rt_spec_dst= key.src;
-
-	rth->u.dst.output=ip_output;
-
-	if (flags&RTCF_LOCAL) {
-		rth->u.dst.input = ip_local_deliver;
-		rth->rt_spec_dst = key.dst;
-	}
-	if (flags&(RTCF_BROADCAST|RTCF_MULTICAST)) {
-		rth->rt_spec_dst = key.src;
-		if (flags&RTCF_LOCAL && !(dev_out->flags&IFF_LOOPBACK))
-			rth->u.dst.output = ip_mc_output;
-#ifdef CONFIG_IP_MROUTE
-		if (res.type == RTN_MULTICAST) {
-			struct in_device *in_dev = in_dev_get(dev_out);
-			if (in_dev) {
-				if (IN_DEV_MFORWARD(in_dev) && !LOCAL_MCAST(daddr)) {
-					rth->u.dst.input = ip_mr_input;
-					rth->u.dst.output = ip_mc_output;
-				}
-				in_dev_put(in_dev);
+		if (oif) {
+			err = -ENODEV;
+			dev_out = dev_get_by_index(oif);
+			if (dev_out == NULL)
+				goto out;
+			if (__in_dev_get(dev_out) == NULL)
+				goto out;	/* Wrong error code */
+			if (saddr) {
+				/* Verify user supplied source address */
+				err = outrt_check_src(saddr, daddr, tos, dev_out);
+				if (err)
+					goto out;
+			} else {
+				int scope;
+				if (LOCAL_MCAST(daddr) || daddr == 0xFFFFFFFF)
+					scope = RT_SCOPE_LINK;
+				else if (MULTICAST(daddr))
+					scope = key.scope;
+				else
+					scope = RT_SCOPE_HOST;
+				saddr = inet_select_addr(dev_out, 0, scope);
 			}
-		}
-#endif
+			res.type = RTN_UNICAST;
+			res.fi = NULL;
+			err = outrt_make_route(rp, &key, daddr, saddr, dev_out,
+					&res);
+		} else
+			err = -ENETUNREACH;
 	}
-
-	rt_set_nexthop(rth, &res, 0);
-
-	rth->rt_flags = flags;
-
-	hash = rt_hash_code(daddr, saddr^(oif<<5), tos);
-	err = rt_intern_hash(hash, rth, rp);
-done:
-	if (free_res)
-		fib_res_put(&res);
+out:
 	if (dev_out)
 		dev_put(dev_out);
 	return err;
 
-e_inval:
-	err = -EINVAL;
-	goto done;
-e_nobufs:
-	err = -ENOBUFS;
-	goto done;
+	/* I don't know what reason this hack was for */
+dest_insanity:
+	daddr = saddr;
+	if (!daddr)
+		daddr = saddr = htonl(INADDR_LOOPBACK);
+	dev_out = &loopback_dev;
+	dev_hold(dev_out);
+	key.oif = loopback_dev.ifindex;
+	res.type = RTN_LOCAL;
+	res.fi = NULL;
+	err = outrt_make_route(rp, &key, daddr, saddr, dev_out, &res);
+	goto out;
 }
 
 int ip_route_output(struct rtable **rp, u32 daddr, u32 saddr, u32 tos, int oif)