adding dns resolution with lwip example

Author: andreagilardoni

libraries/lwIpWrapper/examples/dns_resolution/arduino_secrets.h

@@ -0,0 +1,2 @@
+#define SECRET_SSID ""
+#define SECRET_PASS ""

libraries/lwIpWrapper/examples/dns_resolution/dns_resolution.ino

@@ -0,0 +1,119 @@
+#include <Arduino_DebugUtils.h>
+#include <EthernetC33.h>
+#include <WiFiC3.h>
+#include "arduino_secrets.h"
+
+static char const SSID[] = SECRET_SSID;  /* your network SSID (name) */
+static char const PASS[] = SECRET_PASS;  /* your network password (use for WPA, or use as key for WEP) */
+
+void application();
+
+#define BLOCKING_DNS_RESOLUTION
+
+void setup() {
+    Serial.begin(115200);
+    while(!Serial);
+
+    DEBUG_INFO("Setting up netif");
+
+    Ethernet.begin();
+
+    int res = 0;
+    DEBUG_INFO("Connecting to AP");
+    while((res=WiFi.begin(SSID, SECRET_PASS)) != ESP_CONTROL_OK) {
+        DEBUG_INFO("Connection failed retry: %d", res);
+        delay(1000);
+    }
+    DEBUG_INFO("Connected to AP");
+    DEBUG_INFO("Beginning");
+}
+
+void loop() {
+#ifndef LWIP_USE_TIMER
+    CLwipIf::getInstance().task();
+#endif
+
+    application();
+}
+
+// application stuff
+volatile uint8_t state = 0;
+uint32_t counter = 0;
+
+char* domains[] = {
+    "google.it"
+    , "www.google.com"
+    , "arduino.cc"
+    , "oniudra.cc"
+    , "youtube.it"
+    , "youtube.com"
+    , "github.com"
+    , "drive.google.com"
+};
+
+#ifndef BLOCKING_DNS_RESOLUTION
+void dns_cbk(const IPAddress& ip) {
+    DEBUG_INFO("%u DNS response for %s: %s ",
+        counter,
+        domains[counter % (sizeof(domains)/sizeof(char*))],
+        ip.toString().c_str());
+    state = 1;
+    counter++;
+}
+#endif // BLOCKING_DNS_RESOLUTION
+
+void application() {
+
+    switch(state) {
+    case 0:
+        if(WiFiStation.isDhcpAcquired() && Ethernet.isDhcpAcquired()) {
+            DEBUG_INFO("dhcp acquired");
+
+            state = 1;
+        }
+        break;
+    case 1: {
+        DEBUG_INFO("changing default Interface: \"%s\"", counter%2==0 ? "Ethernet": "WiFiStation");
+
+        CLwipIf::getInstance().setDefaultIface(counter%2==0? (CNetIf*)&Ethernet: (CNetIf*)&WiFiStation);
+
+        DEBUG_INFO("%u Performing DNS request for %s",
+            counter,
+            domains[counter % (sizeof(domains)/sizeof(char*))]);
+#ifdef BLOCKING_DNS_RESOLUTION
+        IPAddress ip;
+
+        auto res = CLwipIf::getInstance().getHostByName(
+            domains[counter % (sizeof(domains)/sizeof(char*))],
+            ip,
+#ifndef LWIP_USE_TIMER
+            true);
+#else
+            false);
+#endif
+
+        counter++;
+        DEBUG_INFO("%u DNS response for %s: %u %s ",
+            counter,
+            domains[counter % (sizeof(domains)/sizeof(char*))],
+            res,
+            ip.toString().c_str());
+#else // BLOCKING_DNS_RESOLUTION
+        state = 2;
+        auto res = CLwipIf::getInstance().getHostByName(
+            domains[counter % (sizeof(domains)/sizeof(char*))],
+            dns_cbk);
+
+        if(res != 1) {
+            counter++;
+        }
+#endif // BLOCKING_DNS_RESOLUTION
+        break;
+    }
+    case 2:
+        // do nothing, request made, wait for request to complete
+        break;
+    }
+
+}
+