Nest: Keep multipath next hops sorted

3 files changed, 37 insertions, 0 deletions

diff --git a/nest/route.h b/nest/route.h
index 3969db6b..bb4674b9 100644
--- a/nest/route.h
+++ b/nest/route.h
@@ -506,6 +506,8 @@ int mpnh__same(struct mpnh *x, struct mpnh *y); /* Compare multipath nexthops */
 static inline int mpnh_same(struct mpnh *x, struct mpnh *y)
 { return (x == y) || mpnh__same(x, y); }
 struct mpnh *mpnh_merge(struct mpnh *x, struct mpnh *y, int rx, int ry, int max, linpool *lp);
+void mpnh_insert(struct mpnh **n, struct mpnh *y);
+int mpnh_is_sorted(struct mpnh *x);
 
 void rta_init(void);
 rta *rta_lookup(rta *);			/* Get rta equivalent to this one, uc++ */
diff --git a/nest/rt-attr.c b/nest/rt-attr.c
index 42b74f34..ab0069b5 100644
--- a/nest/rt-attr.c
+++ b/nest/rt-attr.c
@@ -302,6 +302,34 @@ mpnh_merge(struct mpnh *x, struct mpnh *y, int rx, int ry, int max, linpool *lp)
   return root;
 }
 
+void
+mpnh_insert(struct mpnh **n, struct mpnh *x)
+{
+  for (; *n; n = &((*n)->next))
+  {
+    int cmp = mpnh_compare_node(*n, x);
+
+    if (cmp < 0)
+      continue;
+    else if (cmp > 0)
+      break;
+    else
+      return;
+  }
+
+  x->next = *n;
+  *n = x;
+}
+
+int
+mpnh_is_sorted(struct mpnh *x)
+{
+  for (; x && x->next; x = x->next)
+    if (mpnh_compare_node(x, x->next) >= 0)
+      return 0;
+
+  return 1;
+}
 
 static struct mpnh *
 mpnh_copy(struct mpnh *o)
diff --git a/nest/rt-table.c b/nest/rt-table.c
index 9baf2849..f4df22aa 100644
--- a/nest/rt-table.c
+++ b/nest/rt-table.c
@@ -804,6 +804,13 @@ rte_validate(rte *e)
       return 0;
     }
 
+  if ((e->attrs->dest == RTD_MULTIPATH) && !mpnh_is_sorted(e->attrs->nexthops))
+    {
+      log(L_WARN "Ignoring unsorted multipath route %I/%d received via %s",
+	  n->n.prefix, n->n.pxlen, e->sender->proto->name);
+      return 0;
+    }
+
   return 1;
 }