These files handle the radix tree for the ECMP routes.

The original code from KAME did not take care of address
aliases or multiple ip addresses that have the same
prefix.

Reviewed by:	rwatson, gnn, sam, kmacy, julian

1 files changed, 334 insertions, 0 deletions

diff --git a/sys/net/radix_mpath.c b/sys/net/radix_mpath.c
new file mode 100644
index 0000000..240fb36
--- /dev/null
+++ b/sys/net/radix_mpath.c
@@ -0,0 +1,334 @@
+/*	$KAME: radix_mpath.c,v 1.17 2004/11/08 10:29:39 itojun Exp $	*/
+
+/*
+ * Copyright (C) 2001 WIDE Project.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * THE AUTHORS DO NOT GUARANTEE THAT THIS SOFTWARE DOES NOT INFRINGE
+ * ANY OTHERS' INTELLECTUAL PROPERTIES. IN NO EVENT SHALL THE AUTHORS
+ * BE LIABLE FOR ANY INFRINGEMENT OF ANY OTHERS' INTELLECTUAL
+ * PROPERTIES.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/malloc.h>
+#include <sys/socket.h>
+#include <sys/domain.h>
+#include <sys/syslog.h>
+#include <net/radix.h>
+#include <net/radix_mpath.h>
+#include <net/route.h>
+#include <net/if.h>
+#include <net/if_var.h>
+
+/*
+ * give some jitter to hash, to avoid synchronization between routers
+ */
+static u_int32_t hashjitter;
+
+int
+rn_mpath_capable(struct radix_node_head *rnh)
+{
+
+	return rnh->rnh_multipath;
+}
+
+struct radix_node *
+rn_mpath_next(struct radix_node *rn)
+{
+	struct radix_node *next;
+
+	if (!rn->rn_dupedkey)
+		return NULL;
+	next = rn->rn_dupedkey;
+	if (rn->rn_mask == next->rn_mask)
+		return next;
+	else
+		return NULL;
+}
+
+int
+rn_mpath_count(struct radix_node *rn)
+{
+	int i;
+
+	i = 1;
+	while ((rn = rn_mpath_next(rn)) != NULL)
+		i++;
+	return i;
+}
+
+struct rtentry *
+rt_mpath_matchgate(struct rtentry *rt, struct sockaddr *gate)
+{
+	struct radix_node *rn;
+
+	if (!rn_mpath_next((struct radix_node *)rt))
+		return rt;
+
+	if (!gate)
+		return NULL;
+
+	/* beyond here, we use rn as the master copy */
+	rn = (struct radix_node *)rt;
+	do {
+		rt = (struct rtentry *)rn;
+		/*
+		 * we are removing an address alias that has 
+		 * the same prefix as another address
+		 * we need to compare the interface address because
+		 * rt_gateway is a special sockadd_dl structure
+		 */
+		if (rt->rt_gateway->sa_family == AF_LINK) {
+			if (!memcmp(rt->rt_ifa->ifa_addr, gate, gate->sa_len))
+				break;
+		} else {
+			if (rt->rt_gateway->sa_len == gate->sa_len &&
+			    !memcmp(rt->rt_gateway, gate, gate->sa_len))
+				break;
+		}
+	} while ((rn = rn_mpath_next(rn)) != NULL);
+
+	return (struct rtentry *)rn;
+}
+
+/* 
+ * go through the chain and unlink "rt" from the list
+ * the caller will free "rt"
+ */
+int
+rt_mpath_deldup(struct rtentry *headrt, struct rtentry *rt)
+{
+        struct radix_node *t, *tt;
+
+        if (!headrt || !rt)
+            return (0);
+        t = (struct radix_node *)headrt;
+        tt = rn_mpath_next(t);
+        while (tt) {
+            if (tt == (struct radix_node *)rt) {
+                t->rn_dupedkey = tt->rn_dupedkey;
+                tt->rn_dupedkey = NULL;
+    	        tt->rn_flags &= ~RNF_ACTIVE;
+	        tt[1].rn_flags &= ~RNF_ACTIVE;
+                return (1);
+            }
+            t = tt;
+            tt = rn_mpath_next((struct radix_node *)t);
+        }
+        return (0);
+}
+
+/*
+ * check if we have the same key/mask/gateway on the table already.
+ */
+int
+rt_mpath_conflict(struct radix_node_head *rnh, struct rtentry *rt,
+    struct sockaddr *netmask)
+{
+	struct radix_node *rn, *rn1;
+	struct rtentry *rt1;
+	char *p, *q, *eq;
+	int same, l, skip;
+
+	rn = (struct radix_node *)rt;
+	rn1 = rnh->rnh_lookup(rt_key(rt), netmask, rnh);
+	if (!rn1 || rn1->rn_flags & RNF_ROOT)
+		return 0;
+
+	/*
+	 * unlike other functions we have in this file, we have to check
+	 * all key/mask/gateway as rnh_lookup can match less specific entry.
+	 */
+	rt1 = (struct rtentry *)rn1;
+
+	/* compare key. */
+	if (rt_key(rt1)->sa_len != rt_key(rt)->sa_len ||
+	    bcmp(rt_key(rt1), rt_key(rt), rt_key(rt1)->sa_len))
+		goto different;
+
+	/* key was the same.  compare netmask.  hairy... */
+	if (rt_mask(rt1) && netmask) {
+		skip = rnh->rnh_treetop->rn_offset;
+		if (rt_mask(rt1)->sa_len > netmask->sa_len) {
+			/*
+			 * as rt_mask(rt1) is made optimal by radix.c,
+			 * there must be some 1-bits on rt_mask(rt1)
+			 * after netmask->sa_len.  therefore, in
+			 * this case, the entries are different.
+			 */
+			if (rt_mask(rt1)->sa_len > skip)
+				goto different;
+			else {
+				/* no bits to compare, i.e. same*/
+				goto maskmatched;
+			}
+		}
+
+		l = rt_mask(rt1)->sa_len;
+		if (skip > l) {
+			/* no bits to compare, i.e. same */
+			goto maskmatched;
+		}
+		p = (char *)rt_mask(rt1);
+		q = (char *)netmask;
+		if (bcmp(p + skip, q + skip, l - skip))
+			goto different;
+		/*
+		 * need to go through all the bit, as netmask is not
+		 * optimal and can contain trailing 0s
+		 */
+		eq = (char *)netmask + netmask->sa_len;
+		q += l;
+		same = 1;
+		while (eq > q)
+			if (*q++) {
+				same = 0;
+				break;
+			}
+		if (!same)
+			goto different;
+	} else if (!rt_mask(rt1) && !netmask)
+		; /* no mask to compare, i.e. same */
+	else {
+		/* one has mask and the other does not, different */
+		goto different;
+	}
+
+maskmatched:
+
+	/* key/mask were the same.  compare gateway for all multipaths */
+	do {
+		rt1 = (struct rtentry *)rn1;
+
+		/* sanity: no use in comparing the same thing */
+		if (rn1 == rn)
+			continue;
+        
+		if (rt1->rt_gateway->sa_family == AF_LINK) {
+			if (rt1->rt_ifa->ifa_addr->sa_len != rt->rt_ifa->ifa_addr->sa_len ||
+			    bcmp(rt1->rt_ifa->ifa_addr, rt->rt_ifa->ifa_addr, 
+			    rt1->rt_ifa->ifa_addr->sa_len))
+				continue;
+		} else {
+			if (rt1->rt_gateway->sa_len != rt->rt_gateway->sa_len ||
+			    bcmp(rt1->rt_gateway, rt->rt_gateway,
+			    rt1->rt_gateway->sa_len))
+				continue;
+		}
+
+		/* all key/mask/gateway are the same.  conflicting entry. */
+		return EEXIST;
+	} while ((rn1 = rn_mpath_next(rn1)) != NULL);
+
+different:
+	return 0;
+}
+
+void
+rtalloc_mpath(struct route *ro, int hash)
+{
+	struct radix_node *rn0, *rn;
+	int n;
+
+	/*
+	 * XXX we don't attempt to lookup cached route again; what should
+	 * be done for sendto(3) case?
+	 */
+	if (ro->ro_rt && ro->ro_rt->rt_ifp && (ro->ro_rt->rt_flags & RTF_UP))
+		return;				 /* XXX */
+	ro->ro_rt = rtalloc1(&ro->ro_dst, 1, 0UL);
+
+	/* if the route does not exist or it is not multipath, don't care */
+	if (!ro->ro_rt || !rn_mpath_next((struct radix_node *)ro->ro_rt)) {
+		RT_UNLOCK(ro->ro_rt);
+		return;
+	}
+
+	/* beyond here, we use rn as the master copy */
+	rn0 = rn = (struct radix_node *)ro->ro_rt;
+	n = rn_mpath_count(rn0);
+
+	/* gw selection by Modulo-N Hash (RFC2991) XXX need improvement? */
+	hash += hashjitter;
+	hash %= n;
+	while (hash-- > 0 && rn) {
+		/* stay within the multipath routes */
+		if (rn->rn_dupedkey && rn->rn_mask != rn->rn_dupedkey->rn_mask)
+			break;
+		rn = rn->rn_dupedkey;
+	}
+
+	/* XXX try filling rt_gwroute and avoid unreachable gw  */
+
+	/* if gw selection fails, use the first match (default) */
+	if (!rn) {
+		RT_UNLOCK(ro->ro_rt);
+		return;
+	}
+	
+	rtfree(ro->ro_rt);
+	ro->ro_rt = (struct rtentry *)rn;
+	RT_LOCK(ro->ro_rt);
+	RT_ADDREF(ro->ro_rt);
+	RT_UNLOCK(ro->ro_rt);
+}
+
+extern int	in6_inithead(void **head, int off);
+extern int	in_inithead(void **head, int off);
+
+int
+rn4_mpath_inithead(void **head, int off)
+{
+	struct radix_node_head *rnh;
+
+	hashjitter = arc4random();
+	if (in_inithead(head, off) == 1) {
+		rnh = (struct radix_node_head *)*head;
+		rnh->rnh_multipath = 1;
+		return 1;
+	} else
+		return 0;
+}
+
+int
+rn6_mpath_inithead(void **head, int off)
+{
+	struct radix_node_head *rnh;
+
+	hashjitter = arc4random();
+	if (in6_inithead(head, off) == 1) {
+		rnh = (struct radix_node_head *)*head;
+		rnh->rnh_multipath = 1;
+		return 1;
+	} else
+		return 0;
+}
+