WiFi: ARP gratuitous API for wifi station mode

libraries/ESP8266WiFi/keywords.txt

@@ -108,6 +108,9 @@ psk	KEYWORD2
 BSSID	KEYWORD2
 BSSIDstr	KEYWORD2
 RSSI	KEYWORD2
+stationKeepAliveSetIntervalMs	KEYWORD2
+stationKeepAliveStop	KEYWORD2
+stationKeepAliveNow	KEYWORD2
 enableInsecureWEP	KEYWORD2
 getListenInterval	KEYWORD2
 isSleepLevelMax		KEYWORD2

libraries/ESP8266WiFi/src/ESP8266WiFiSTA.cpp

@@ -34,6 +34,7 @@
 #include "mem.h"
 #include "user_interface.h"
 #include "smartconfig.h"
+#include "Schedule.h"
 
 extern "C" {
 #include "lwip/err.h"
@@ -43,6 +44,12 @@ extern "C" {
 #if LWIP_IPV6
 #include "lwip/netif.h" // struct netif
 #endif
+#if LWIP_VERSION_MAJOR == 1
+#include "netif/wlan_lwip_if.h" // eagle_lwip_getif()
+#include "netif/etharp.h" // gratuitous arp
+#else
+#include "lwip/etharp.h" // gratuitous arp
+#endif
 }
 
 #include "debug.h"
@@ -89,7 +96,7 @@ static bool sta_config_equal(const station_config& lhs, const station_config& rh
             return false;
         }
     }
-    
+
     if(lhs.threshold.rssi != rhs.threshold.rssi) {
         return false;
     }
@@ -704,7 +711,61 @@ int32_t ESP8266WiFiSTAClass::RSSI(void) {
     return wifi_station_get_rssi();
 }
 
+void ESP8266WiFiSTAClass::stationKeepAliveNow ()
+{
+    for (netif* interface = netif_list; interface != nullptr; interface = interface->next)
+         if (
+               (interface->flags & NETIF_FLAG_LINK_UP)
+            && (interface->flags & NETIF_FLAG_UP)
+#if LWIP_VERSION_MAJOR == 1
+            && interface == eagle_lwip_getif(STATION_IF) /* lwip1 does not set if->num properly */
+            && (!ip_addr_isany(&interface->ip_addr))
+#else
+            && interface->num == STATION_IF
+            && (!ip4_addr_isany_val(*netif_ip4_addr(interface)))
+#endif
+        )
+        {
+            etharp_gratuitous(interface);
+            break;
+        }
+}
 
+void ESP8266WiFiSTAClass::stationKeepAliveSetIntervalMs (uint32_t ms)
+{
+    uint32_t us;
+    if (ms > std::numeric_limits<uint32_t>::max() / 1000)
+        // for sanity only, 49 days is not really meaningful
+        us = std::numeric_limits<uint32_t>::max();
+    else
+        us = ms * 1000;
+
+    // cancel possibly already scheduled future events
+    _keepStationState++;
+
+    if (us)
+    {
+        // send one now
+        stationKeepAliveNow();
+
+        // schedule next ones
+        int checkState = _keepStationState;
+        schedule_recurrent_function_us([&, checkState]()
+        {
+            // this recurring scheduled function will be cancelled
+            // when this->_keepStationState != checkState
+            if (checkState != this->_keepStationState)
+                // cancel this recurring event
+                return false;
+
+            // send gratuitous ARP
+            this->stationKeepAliveNow();
+
+            // keep on with next event
+            return true;
+        }, us);
+    }
+}
 
 // -----------------------------------------------------------------------------------------------------------------------
 // -------------------------------------------------- STA remote configure -----------------------------------------------

libraries/ESP8266WiFi/src/ESP8266WiFiSTA.h

@@ -41,8 +41,8 @@ class ESP8266WiFiSTAClass {
         wl_status_t begin(const String& ssid, const String& passphrase = emptyString, int32_t channel = 0, const uint8_t* bssid = NULL, bool connect = true);
         wl_status_t begin();
 
-        //The argument order for ESP is not the same as for Arduino. However, there is compatibility code under the hood 
-        //to detect Arduino arg order, and handle it correctly. Be aware that the Arduino default value handling doesn't 
+        //The argument order for ESP is not the same as for Arduino. However, there is compatibility code under the hood
+        //to detect Arduino arg order, and handle it correctly. Be aware that the Arduino default value handling doesn't
         //work here (see Arduino docs for gway/subnet defaults). In other words: at least 3 args must always be given.
         bool config(IPAddress local_ip, IPAddress gateway, IPAddress subnet, IPAddress dns1 = (uint32_t)0x00000000, IPAddress dns2 = (uint32_t)0x00000000);
 
@@ -83,13 +83,26 @@ class ESP8266WiFiSTAClass {
 
         int32_t RSSI();
 
+        // disable(0) or enable/update automatic sending of Gratuitous ARP packets
+        // a gratuitous ARP packet is sent at start, then
+        // based on a time interval in milliseconds, default 1s
+        void stationKeepAliveSetIntervalMs (uint32_t ms = 1000);
+
+        // request for stopping arp gratuitous packets
+        void stationKeepAliveStop () { stationKeepAliveSetIntervalMs(0); }
+
+        // immediately send one gratuitous ARP from STA
+        static void stationKeepAliveNow ();
+
         static void enableInsecureWEP (bool enable = true) { _useInsecureWEP = enable; }
 
     protected:
 
         static bool _useStaticIp;
         static bool _useInsecureWEP;
 
+        int _keepStationState = 0;
+
     // ----------------------------------------------------------------------------------------------
     // ------------------------------------ STA remote configure  -----------------------------------
     // ----------------------------------------------------------------------------------------------

tests/host/common/MocklwIP.cpp

@@ -26,4 +26,11 @@ const ip_addr_t* sntp_getserver(u8_t)
     return IP_ADDR_ANY;
 }
 
+err_t etharp_request(struct netif *netif, const ip4_addr_t *ipaddr)
+{
+    (void)netif;
+    (void)ipaddr;
+    return ERR_OK;
+}
+
 } // extern "C"