add code for sending gratuitous ARP periodically

components/lwip/Kconfig

@@ -128,6 +128,23 @@ config LWIP_ETHARP_TRUST_IP_MAC
         So the recommendation is to disable this option. 
         Here the LAN peer means the other side to which the ESP station or soft-AP is connected.
 
+config ESP_GRATUITOUS_ARP
+    bool "Send gratuitous ARP periodically"
+    default y
+    help 
+        Enable this option allows to send gratuitous ARP periodically.
+
+        This option solve the compatibility issues.If the ARP table of the AP is old, and the AP
+        doesn't send ARP request to update it's ARP table, this will lead to the STA sending IP packet fail.
+        Thus we send gratuitous ARP periodically to let AP update it's ARP table.
+
+config GARP_TMR_INTERVAL
+    int "GARP timer interval(seconds)"
+    default 60
+    depends on ESP_GRATUITOUS_ARP
+    help
+        Set the timer interval for gratuitous ARP. The default value is 60s
+
 config TCPIP_RECVMBOX_SIZE
     int "TCPIP task receive mail box size"
     default 32

components/lwip/core/netif.c

@@ -332,6 +332,16 @@ netif_set_addr(struct netif *netif, const ip4_addr_t *ipaddr, const ip4_addr_t *
 
 #endif /* LWIP_IPV4*/
 
+/**
+ * Set the netif flags for GARP
+ */
+#if ESP_GRATUITOUS_ARP
+void netif_set_garp_flag(struct netif *netif)
+{
+  netif->flags |= NETIF_FLAG_GARP;
+}
+#endif
+
 /**
  * Remove a network interface from the list of lwIP netifs.
  *

components/lwip/core/timers.c

@@ -70,6 +70,10 @@
 extern void dhcps_coarse_tmr(void);
 #endif 
 
+#if ESP_GRATUITOUS_ARP
+extern void garp_tmr(void);
+#endif
+
 /** This array contains all stack-internal cyclic timers. To get the number of
   * timers, use LWIP_ARRAYSIZE() */
 const struct lwip_cyclic_timer lwip_cyclic_timers[] = {
@@ -84,6 +88,9 @@ const struct lwip_cyclic_timer lwip_cyclic_timers[] = {
 #endif /* IP_REASSEMBLY */
 #if LWIP_ARP
   {ARP_TMR_INTERVAL, HANDLER(etharp_tmr)},
+#if ESP_GRATUITOUS_ARP
+  {GARP_TMR_INTERVAL, HANDLER(garp_tmr)},
+#endif
 #endif /* LWIP_ARP */
 #if LWIP_DHCP
   {DHCP_COARSE_TIMER_MSECS, HANDLER(dhcp_coarse_tmr)},

components/lwip/include/lwip/lwip/netif.h

@@ -99,6 +99,11 @@ extern "C" {
  * Set by the netif driver in its init function. */
 #define NETIF_FLAG_MLD6         0x40U
 
+#if ESP_GRATUITOUS_ARP
+/** If set, the netif will send gratuitous ARP periodically */
+#define NETIF_FLAG_GARP         0x80U
+#endif
+
 #if LWIP_CHECKSUM_CTRL_PER_NETIF
 #define NETIF_CHECKSUM_GEN_IP       0x0001
 #define NETIF_CHECKSUM_GEN_UDP      0x0002
@@ -362,6 +367,11 @@ struct netif *netif_add(struct netif *netif,
 void netif_set_addr(struct netif *netif, const ip4_addr_t *ipaddr, const ip4_addr_t *netmask,
                     const ip4_addr_t *gw);
 #endif /* LWIP_IPV4 */
+
+#if ESP_GRATUITOUS_ARP
+void netif_set_garp_flag(struct netif *netif);
+#endif
+
 void netif_remove(struct netif * netif);
 
 /* Returns a network interface given its name. The name is of the form

components/lwip/include/lwip/lwip/opt.h

@@ -318,8 +318,12 @@
  * The formula expects settings to be either '0' or '1'.
  */
 #ifndef MEMP_NUM_SYS_TIMEOUT
+#if ESP_LWIP
+#define MEMP_NUM_SYS_TIMEOUT            (LWIP_TCP + IP_REASSEMBLY + (LWIP_ARP + (ESP_GRATUITOUS_ARP ? 1 : 0)) + (2*LWIP_DHCP + (ESP_DHCPS_TIMER ? 1 : 0)) + LWIP_AUTOIP + LWIP_IGMP + LWIP_DNS + (PPP_SUPPORT*6*MEMP_NUM_PPP_PCB) + (LWIP_IPV6 ? (1 + LWIP_IPV6_REASS + LWIP_IPV6_MLD) : 0))
+#else
 #define MEMP_NUM_SYS_TIMEOUT            (LWIP_TCP + IP_REASSEMBLY + LWIP_ARP + (2*LWIP_DHCP) + LWIP_AUTOIP + LWIP_IGMP + LWIP_DNS + (PPP_SUPPORT*6*MEMP_NUM_PPP_PCB) + (LWIP_IPV6 ? (1 + LWIP_IPV6_REASS + LWIP_IPV6_MLD) : 0))
 #endif
+#endif
 
 /**
  * MEMP_NUM_NETBUF: the number of struct netbufs.

components/lwip/include/lwip/netif/etharp.h

@@ -102,6 +102,11 @@ struct etharp_q_entry {
 };
 #endif /* ARP_QUEUEING */
 
+#if ESP_GRATUITOUS_ARP
+#define GARP_TMR_INTERVAL (CONFIG_GARP_TMR_INTERVAL*1000UL)
+void garp_tmr(void);
+#endif
+
 #define etharp_init() /* Compatibility define, no init needed. */
 void etharp_tmr(void);
 s8_t etharp_find_addr(struct netif *netif, const ip4_addr_t *ipaddr,

components/lwip/include/lwip/port/lwipopts.h

@@ -738,6 +738,7 @@
 #define ESP_LWIP_LOGI(...)              ESP_LOGI("lwip", __VA_ARGS__)
 #define ESP_PING                        1
 #define ESP_HAS_SELECT                  1
+#define ESP_GRATUITOUS_ARP              CONFIG_ESP_GRATUITOUS_ARP
 
 #if CONFIG_LWIP_IRAM_OPTIMIZATION
 #define ESP_IRAM_ATTR                   IRAM_ATTR

components/lwip/netif/etharp.c

@@ -52,6 +52,7 @@
 #include "lwip/snmp.h"
 #include "lwip/dhcp.h"
 #include "lwip/autoip.h"
+#include "lwip/netif.h"
 
 #include <string.h>
 
@@ -129,6 +130,22 @@ static u8_t etharp_cached_entry;
 
 static err_t etharp_request_dst(struct netif *netif, const ip4_addr_t *ipaddr, const struct eth_addr* hw_dst_addr);
 
+#if ESP_GRATUITOUS_ARP
+
+void garp_tmr(void)
+{
+  struct netif* garp_netif = NULL;
+
+  for (garp_netif = netif_list; garp_netif != NULL; garp_netif = garp_netif->next) {
+    if (netif_is_up(garp_netif) && netif_is_link_up(garp_netif) && !ip4_addr_isany_val(*netif_ip4_addr(garp_netif))) {
+      if ((garp_netif->flags & NETIF_FLAG_ETHARP) && (garp_netif->flags & NETIF_FLAG_GARP)) {
+        etharp_gratuitous(garp_netif);
+      }
+    }
+  }
+}
+#endif
+
 
 #if ARP_QUEUEING
 /**

components/tcpip_adapter/tcpip_adapter_lwip.c

@@ -26,6 +26,7 @@
 #include "lwip/ip6_addr.h"
 #include "lwip/nd6.h"
 #include "lwip/priv/tcpip_priv.h"
+#include "lwip/netif.h"
 #if LWIP_DNS /* don't build if not configured for use in lwipopts.h */
 #include "lwip/dns.h"
 #endif
@@ -184,6 +185,12 @@ esp_err_t tcpip_adapter_start(tcpip_adapter_if_t tcpip_if, uint8_t *mac, tcpip_a
         netif_init = tcpip_if_to_netif_init_fn(tcpip_if);
         assert(netif_init != NULL);
         netif_add(esp_netif[tcpip_if], &ip_info->ip, &ip_info->netmask, &ip_info->gw, NULL, netif_init, tcpip_input);
+
+#if ESP_GRATUITOUS_ARP
+        if (tcpip_if == TCPIP_ADAPTER_IF_STA || tcpip_if == TCPIP_ADAPTER_IF_ETH) {
+            netif_set_garp_flag(esp_netif[tcpip_if]);
+        }
+#endif
     }
 
     if (tcpip_if == TCPIP_ADAPTER_IF_AP) {