new network feature: NAPT (widely known as NAT) (#6360)

* lwIP: napt patches (enabled with lwip2 w/o IPv6 w/ features)

libraries/ESP8266WiFi/examples/RangeExtender-NAPT/RangeExtender-NAPT.ino

@@ -0,0 +1,97 @@
+
+// NAPT example released to public domain
+
+#if LWIP_FEATURES && !LWIP_IPV6
+
+#define HAVE_NETDUMP 0
+
+#ifndef STASSID
+#define STASSID "mynetwork"
+#define STAPSK  "mynetworkpassword"
+#endif
+
+#include <ESP8266WiFi.h>
+#include <lwip/napt.h>
+#include <lwip/dns.h>
+#include <dhcpserver.h>
+
+#define NAPT 1000
+#define NAPT_PORT 10
+
+#if HAVE_NETDUMP
+
+#include <NetDump.h>
+
+void dump(int netif_idx, const char* data, size_t len, int out, int success) {
+  (void)success;
+  Serial.print(out ? F("out ") : F(" in "));
+  Serial.printf("%d ", netif_idx);
+
+  // optional filter example: if (netDump_is_ARP(data))
+  {
+    netDump(Serial, data, len);
+    //netDumpHex(Serial, data, len);
+  }
+}
+#endif
+
+void setup() {
+  Serial.begin(115200);
+  Serial.printf("\n\nNAPT Range extender\n");
+  Serial.printf("Heap on start: %d\n", ESP.getFreeHeap());
+
+#if HAVE_NETDUMP
+  phy_capture = dump;
+#endif
+
+  // first, connect to STA so we can get a proper local DNS server
+  WiFi.mode(WIFI_STA);
+  WiFi.begin(STASSID, STAPSK);
+  while (WiFi.status() != WL_CONNECTED) {
+    Serial.print('.');
+    delay(500);
+  }
+  Serial.printf("\nSTA: %s (dns: %s / %s)\n",
+                WiFi.localIP().toString().c_str(),
+                WiFi.dnsIP(0).toString().c_str(),
+                WiFi.dnsIP(1).toString().c_str());
+
+  // give DNS servers to AP side
+  dhcps_set_dns(0, WiFi.dnsIP(0));
+  dhcps_set_dns(1, WiFi.dnsIP(1));
+
+  WiFi.softAPConfig(  // enable AP, with android-compatible google domain
+    IPAddress(172, 217, 28, 254),
+    IPAddress(172, 217, 28, 254),
+    IPAddress(255, 255, 255, 0));
+  WiFi.softAP(STASSID "extender", STAPSK);
+  Serial.printf("AP: %s\n", WiFi.softAPIP().toString().c_str());
+
+  Serial.printf("Heap before: %d\n", ESP.getFreeHeap());
+  err_t ret = ip_napt_init(NAPT, NAPT_PORT);
+  Serial.printf("ip_napt_init(%d,%d): ret=%d (OK=%d)\n", NAPT, NAPT_PORT, (int)ret, (int)ERR_OK);
+  if (ret == ERR_OK) {
+    ret = ip_napt_enable_no(SOFTAP_IF, 1);
+    Serial.printf("ip_napt_enable_no(SOFTAP_IF): ret=%d (OK=%d)\n", (int)ret, (int)ERR_OK);
+    if (ret == ERR_OK) {
+      Serial.printf("WiFi Network '%s' with same password is now NATed behind '%s'\n", STASSID "extender", STASSID);
+    }
+  }
+  Serial.printf("Heap after napt init: %d\n", ESP.getFreeHeap());
+  if (ret != ERR_OK) {
+    Serial.printf("NAPT initialization failed\n");
+  }
+}
+
+#else
+
+void setup() {
+  Serial.begin(115200);
+  Serial.printf("\n\nNAPT not supported in this configuration\n");
+}
+
+#endif
+
+void loop() {
+}
+

libraries/ESP8266mDNS/src/LEAmDNS_Control.cpp

@@ -22,7 +22,6 @@
  *
  */
 
-#include <arch/cc.h>
 #include <sys/time.h>
 #include <IPAddress.h>
 #include <AddrList.h>