First stable compilation with ModbusRTU and ModbusTCP

lib/modbus-esp8266/ModbusTCP.h

@@ -0,0 +1,40 @@
+/*
+    Modbus Library for Arduino
+    ModbusTCP for ESP8266/ESP32
+    Copyright (C) 2020 Alexander Emelianov (a.m.emelianov@gmail.com)
+*/
+
+#pragma once
+#if defined(ESP8266)
+#include <ESP8266WiFi.h>
+#elif defined(ESP32)
+#include <WiFi.h>
+#endif
+
+#include "ModbusAPI.h"
+#include "ModbusTCPTemplate.h"
+
+class WiFiServerESPWrapper : public WiFiServer {
+  public:
+    WiFiServerESPWrapper(uint16_t port) : WiFiServer(port) {}
+    inline WiFiClient accept() {
+        return available();
+    }
+};
+
+class ModbusTCP : public ModbusAPI<ModbusTCPTemplate<WiFiServerESPWrapper, WiFiClient>> {
+#if defined(MODBUSIP_USE_DNS)
+  private:
+    static IPAddress resolver(const char *host) {
+        IPAddress remote_addr;
+        if (WiFi.hostByName(host, remote_addr))
+            return remote_addr;
+        return IPADDR_NONE;
+    }
+
+  public:
+    ModbusTCP() : ModbusAPI() {
+        resolve = resolver;
+    }
+#endif
+};