LwipIntfDev - method end() to enable repeated begin

Author: JAndrassy

cores/esp8266/LwipIntfDev.h

@@ -68,6 +68,7 @@ class LwipIntfDev: public LwipIntf, public RawDev
 
     // default mac-address is inferred from esp8266's STA interface
     boolean begin(const uint8_t* macAddress = nullptr, const uint16_t mtu = DEFAULT_MTU);
+    void end();
 
     const netif* getNetIf() const
     {
@@ -138,6 +139,7 @@ class LwipIntfDev: public LwipIntf, public RawDev
     int8_t   _intrPin;
     uint8_t  _macAddress[6];
     bool     _started;
+    bool     _scheduled;
     bool     _default;
 };
 
@@ -272,22 +274,39 @@ boolean LwipIntfDev<RawDev>::begin(const uint8_t* macAddress, const uint16_t mtu
         }
     }
 
-    if (_intrPin < 0
-        && !schedule_recurrent_function_us(
-            [&]()
-            {
-                this->handlePackets();
-                return true;
-            },
-            100))
+    if (_intrPin < 0 && !_scheduled)
     {
-        netif_remove(&_netif);
-        return false;
+        if (schedule_recurrent_function_us(
+                [&]()
+                {
+                    this->handlePackets();
+                    return true;
+                },
+                100))
+        {
+            _scheduled = true;
+        }
+        else
+        {
+            netif_remove(&_netif);
+            return false;
+        }
     }
 
     return true;
 }
 
+template<class RawDev>
+void LwipIntfDev<RawDev>::end()
+{
+    netif_remove(&_netif);
+    ip_addr_copy(_netif.ip_addr, ip_addr_any);  // to allow DHCP at next begin
+    ip_addr_copy(_netif.netmask, ip_addr_any);
+    ip_addr_copy(_netif.gw, ip_addr_any);
+    _started = false;
+    RawDev::end();
+}
+
 template<class RawDev>
 wl_status_t LwipIntfDev<RawDev>::status()
 {