net/neighbor: Skip Neighbor request if ip address is invalid at ipv6

Supports no Neighbor request for invalid routing addresses in cross-segment communication

Signed-off-by: zhangkai25 <zhangkai25@xiaomi.com>

net/icmpv6/icmpv6_neighbor.c

@@ -257,6 +257,11 @@ int icmpv6_neighbor(FAR struct net_driver_s *dev,
 
       net_ipv6addr_copy(lookup, dev->d_ipv6draddr);
 #endif
+
+      if (net_is_addr_unspecified(lookup))
+        {
+          return -EHOSTUNREACH;
+        }
     }
 
   /* No ARP packet if this device do not support ARP */

net/neighbor/neighbor_ethernet_out.c

@@ -135,6 +135,12 @@ void neighbor_ethernet_out(FAR struct net_driver_s *dev)
 
           net_ipv6addr_copy(ipaddr, dev->d_ipv6draddr);
 #endif
+
+          if (net_is_addr_unspecified(ipaddr))
+            {
+              dev->d_len = 0;
+              return;
+            }
         }
       else
         {