ipv6 send multicast data fail when src address is nul

src/core/ipv6/ip6.c

@@ -174,7 +174,15 @@ ip6_route(const ip6_addr_t *src, const ip6_addr_t *dest)
     }
     /* Again, do not use any other netif in this case, as that could result in
      * zone boundary violations. */
+#if ESP_IPV6
+    if (ip6_addr_ismulticast(dest) && ip6_addr_isany(src)) { 
+      return netif_default;
+    } else {
+      return NULL;
+    }
+#else
     return NULL;
+#endif /* ESP_IPV6 */
   }
 
   /* We come here only if neither source nor destination is scoped. */

src/core/udp.c

@@ -587,13 +587,6 @@ udp_sendto_chksum(struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *dst_ip,
             netif = ip4_route_src(ip_2_ip4(&pcb->local_ip), &pcb->mcast_ip4);
           }
         }
-#if LWIP_IPV6
-#if ESP_LWIP      
-        else if (IP_IS_V6(dst_ip)) {
-            dst_ip =&pcb->local_ip;
-        }
-#endif /* ESP_LWIP */
-#endif /* LWIP_IPV6 */
 #endif /* LWIP_IPV4 */
     }