Fix kernel_addresses when called with ifindex == 0.

xroute.c

@@ -204,7 +204,7 @@ filter_address(struct kernel_addr *addr, void *data) {
     int maxroutes = *(int *)args[0];
     struct kernel_route *routes = (struct kernel_route*)args[1];
     int *found = (int *)args[2];
-    int ifindex = args[3] ? *(int*)args[3] : 0;
+    int ifindex = *(int*)args[3];
     int ll = args[4] ? !!*(int*)args[4] : 0;
     struct kernel_route *route = NULL;
 
@@ -214,7 +214,8 @@ filter_address(struct kernel_addr *addr, void *data) {
     if(ll == !IN6_IS_ADDR_LINKLOCAL(&addr->addr))
         return 0;
 
-    if(addr->ifindex != ifindex)
+    /* ifindex may be 0 -- see kernel_addresses */
+    if(ifindex && addr->ifindex != ifindex)
         return 0;
 
     route = &routes[*found];
@@ -229,6 +230,8 @@ filter_address(struct kernel_addr *addr, void *data) {
     return 1;
 }
 
+/* ifindex is 0 for all interfaces.  ll indicates whether we are
+   interested in link-local or global addresses. */
 int
 kernel_addresses(int ifindex, int ll, struct kernel_route *routes,
                  int maxroutes)