fix(lwip): Filter out V6 packets if V6 is not enabled

the ESP might accept and act on some IPv6 packets, even though IPv6 is not enabled for the interface in Arduino. This change makes the ESP ignore all IPv6 packets if IPv6 address is not available.

Author: me-no-dev

Diff for: libraries/Network/src/NetworkInterface.cpp

@@ -11,6 +11,7 @@
 #include "lwip/ip_addr.h"
 #include "lwip/err.h"
 #include "lwip/netif.h"
+#include "lwip/dns.h"
 #include "dhcpserver/dhcpserver.h"
 #include "dhcpserver/dhcpserver_options.h"
 #include "esp32-hal-log.h"
@@ -34,6 +35,17 @@ NetworkInterface *getNetifByID(Network_Interface_ID id) {
   return NULL;
 }
 
+#if CONFIG_LWIP_HOOK_IP6_INPUT_CUSTOM
+extern "C" int lwip_hook_ip6_input(struct pbuf *p, struct netif *inp) {
+  if (ip6_addr_isany_val(inp->ip6_addr[0].u_addr.ip6)) {
+    // We don't have an LL address -> eat this packet here, so it won't get accepted on input netif
+    pbuf_free(p);
+    return 1;
+  }
+  return 0;
+}
+#endif
+
 static void _ip_event_cb(void *arg, esp_event_base_t event_base, int32_t event_id, void *event_data) {
   if (event_base == IP_EVENT) {
     NetworkInterface *netif = NULL;