IPv6 support: Add proper link-local and SLAAC in STA and WifiMulti

This patch partially depends on:
espressif/esp32-arduino-lib-builder#67
Without this patch we will get only Link local IPv6 (still useful for MDNS and etc).
With patch we will get also global IPv6 address by SLAAC.
By default IPv6 disabled, until it is properly tested.

Tested on BasicHttpClient by adding:
wifiMulti.IPv6(true);
before: wifiMulti.addAP() call

Enabling Core Debug Level: verbose
If IP6 obtained, in logs will be visible:
[  8028][V][WiFiGeneric.cpp:380] _arduino_event_cb(): IF[0] Got IPv6: IP Index: 0, Zone: 2, fe80:0000:0000:0000:xxxx:xxxx:xxxx:xxxx
[  8028][D][WiFiGeneric.cpp:852] _eventCallback(): Arduino Event: 8 - STA_GOT_IP6
[ 11028][V][WiFiGeneric.cpp:380] _arduino_event_cb(): IF[0] Got IPv6: IP Index: 1, Zone: 0, 2a0d:yyyy:0000:4000:yyyy:yyyy:yyyy:yyyy
[ 11028][D][WiFiGeneric.cpp:852] _eventCallback(): Arduino Event: 8 - STA_GOT_IP6

This is linked to: espressif#6242

Signed-off-by: Denys Fedoryshchenko <[email protected]>

Author: nuclearcat

Diff for: libraries/WiFi/src/WiFiGeneric.cpp

@@ -866,8 +866,8 @@ esp_err_t WiFiGenericClass::_eventCallback(arduino_event_t *event)
     } else if(event->event_id == ARDUINO_EVENT_WIFI_STA_CONNECTED) {
         WiFiSTAClass::_setStatus(WL_IDLE_STATUS);
         setStatusBits(STA_CONNECTED_BIT);
-
-        //esp_netif_create_ip6_linklocal(esp_netifs[ESP_IF_WIFI_STA]);
+        if (getStatusBits() & WIFI_WANT_IP6_BIT)
+            esp_netif_create_ip6_linklocal(esp_netifs[ESP_IF_WIFI_STA]);
     } else if(event->event_id == ARDUINO_EVENT_WIFI_STA_DISCONNECTED) {
         uint8_t reason = event->event_info.wifi_sta_disconnected.reason;
         log_w("Reason: %u - %s", reason, reason2str(reason));

Diff for: libraries/WiFi/src/WiFiGeneric.h

@@ -138,6 +138,7 @@ static const int WIFI_SCANNING_BIT = BIT11;
 static const int WIFI_SCAN_DONE_BIT= BIT12;
 static const int WIFI_DNS_IDLE_BIT = BIT13;
 static const int WIFI_DNS_DONE_BIT = BIT14;
+static const int WIFI_WANT_IP6_BIT = BIT15;
 
 typedef enum {
 	WIFI_RX_ANT0 = 0,

Diff for: libraries/WiFi/src/WiFiMulti.cpp

@@ -30,6 +30,7 @@
 
 WiFiMulti::WiFiMulti()
 {
+    ipv6_support = false;
 }
 
 WiFiMulti::~WiFiMulti()
@@ -160,6 +161,8 @@ uint8_t WiFiMulti::run(uint32_t connectTimeout)
             log_i("[WIFI] Connecting BSSID: %02X:%02X:%02X:%02X:%02X:%02X SSID: %s Channel: %d (%d)", bestBSSID[0], bestBSSID[1], bestBSSID[2], bestBSSID[3], bestBSSID[4], bestBSSID[5], bestNetwork.ssid, bestChannel, bestNetworkDb);
 
             WiFi.begin(bestNetwork.ssid, bestNetwork.passphrase, bestChannel, bestBSSID);
+            if (ipv6_support == true)
+                WiFi.IPv6(true);
             status = WiFi.status();
 
             auto startTime = millis();
@@ -202,3 +205,7 @@ uint8_t WiFiMulti::run(uint32_t connectTimeout)
 
     return status;
 }
+
+void WiFiMulti::IPv6(bool state) {
+    ipv6_support = state;
+}

Diff for: libraries/WiFi/src/WiFiMulti.h

@@ -42,10 +42,12 @@ class WiFiMulti
 
     bool addAP(const char* ssid, const char *passphrase = NULL);
 
+    void IPv6(bool state);
     uint8_t run(uint32_t connectTimeout=5000);
 
 private:
     std::vector<WifiAPlist_t> APlist;
+    bool ipv6_support;
 };
 
 #endif /* WIFICLIENTMULTI_H_ */

Diff for: libraries/WiFi/src/WiFiSTA.cpp

@@ -726,6 +726,19 @@ bool WiFiSTAClass::enableIpV6()
     return esp_netif_create_ip6_linklocal(get_esp_interface_netif(ESP_IF_WIFI_STA)) == ESP_OK;
 }
 
+/**
+ * Enable IPv6 support on the station interface.
+ * @return true on success
+ */
+bool WiFiSTAClass::IPv6(bool state)
+{
+   if (state)
+       WiFiGenericClass::setStatusBits(WIFI_WANT_IP6_BIT);
+   else
+       WiFiGenericClass::clearStatusBits(WIFI_WANT_IP6_BIT);
+   return true;
+}
+
 /**
  * Get the station interface IPv6 address.
  * @return IPv6Address

Diff for: libraries/WiFi/src/WiFiSTA.h

@@ -84,6 +84,7 @@ class WiFiSTAClass
     uint8_t subnetCIDR();
 
     bool enableIpV6();
+    bool IPv6(bool state);
     IPv6Address localIPv6();
 
     // STA WiFi info