added ArduinoWiFiServer with send-to-all-clients functionality (#7612)

and with available() working according to Arduino documentation
plus PagerServer example

libraries/ESP8266WiFi/examples/PagerServer/PagerServer.ino

@@ -0,0 +1,72 @@
+/*
+  Pager Server
+
+  The ESP8266WiFi library's WiFiServer and WiFiServerSecure
+  work differently then WiFiServer and EthernetSever
+  in Arduino networking libraries.
+  This example demonstrates the ArduinoWiFiServer,
+  which enhances the WiFiServer.
+  ArduinoWiFiServer has available() behaving as documented
+  and supports send-to-all-clients functionality, which
+  is not implemented in ESP8266WiFi library's WiFiServer
+  and WiFiServerSecure.
+
+  The example is a simple server that echoes any incoming
+  messages to all connected clients. Connect two or more
+  telnet sessions to see how server.available() and
+  server.print() work.
+
+  created in September 2020 for ESP8266WiFi library
+  by Juraj Andrassy https://github.com/jandrassy
+*/
+
+#include <ESP8266WiFi.h>
+#include <ArduinoWiFiServer.h>
+
+#ifndef STASSID
+#define STASSID "your-ssid"
+#define STAPSK  "your-password"
+#endif
+
+const char* ssid     = STASSID;
+const char* password = STAPSK;
+
+ArduinoWiFiServer server(2323);
+
+void setup() {
+
+  Serial.begin(115200);
+
+  Serial.println();
+  Serial.print("Connecting to ");
+  Serial.println(ssid);
+
+  WiFi.begin(ssid, password);
+
+  while (WiFi.status() != WL_CONNECTED) {
+    delay(500);
+    Serial.print(".");
+  }
+
+  server.begin();
+
+  IPAddress ip = WiFi.localIP();
+  Serial.println();
+  Serial.println("Connected to WiFi network.");
+  Serial.print("To access the server, connect with Telnet client to ");
+  Serial.print(ip);
+  Serial.println(" 2323");
+}
+
+void loop() {
+
+  WiFiClient client = server.available(); // returns first client which has data to read or a 'false' client
+  if (client) { // client is true only if it is connected and has data to read
+    String s = client.readStringUntil('\n'); // read the message incoming from one of the clients
+    s.trim(); // trim eventual \r
+    Serial.println(s); // print the message to Serial Monitor
+    client.print("echo: "); // this is only for the sending client
+    server.println(s); // send the message to all connected clients
+    server.flush(); // flush the buffers
+  }
+}

libraries/ESP8266WiFi/src/ArduinoWiFiServer.h

@@ -0,0 +1,135 @@
+/*
+  ArduinoWiFiServer.h - Arduino compatible WiFiServer
+  implementation for ESP8266Wifi library.
+  Copyright (c) 2020 Juraj Andrassy
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#ifndef arduinowifiserver_h
+#define arduinowifiserver_h
+
+#include <ESP8266WiFi.h>
+
+#ifndef MAX_MONITORED_CLIENTS
+#define MAX_MONITORED_CLIENTS 5
+#endif
+
+template <class TServer, class TClient>
+class ArduinoComptibleWiFiServerTemplate : public TServer {
+public:
+
+  ArduinoComptibleWiFiServerTemplate(const IPAddress& addr, uint16_t port) : TServer(addr, port) {}
+  ArduinoComptibleWiFiServerTemplate(uint16_t port) : TServer(port) {}
+  virtual ~ArduinoComptibleWiFiServerTemplate() {}
+
+  // https://www.arduino.cc/en/Reference/EthernetServerAccept
+  TClient accept() {
+    return TServer::available();
+  }
+
+  // https://www.arduino.cc/en/Reference/WiFiServerAvailable
+  TClient available() {
+
+    // update connected clients
+    for (uint8_t i = 0; i < MAX_MONITORED_CLIENTS; i++) {
+      if (!connectedClients[i]) {
+        connectedClients[i] = accept();
+      }
+    }
+    // find next client with data available
+    for (uint8_t i = 0; i < MAX_MONITORED_CLIENTS; i++) {
+      if (index == MAX_MONITORED_CLIENTS) {
+        index = 0;
+      }
+      TClient& client = connectedClients[index];
+      index++;
+      if (client.available())
+        return client;
+    }
+    return TClient(); // no client with data found
+  }
+
+  virtual size_t write(uint8_t b) override {
+    return write(&b, 1);
+  }
+
+  virtual size_t write(const uint8_t *buf, size_t size) override {
+    if (size == 0)
+      return 0;
+    size_t ret = 0;
+    size_t a = size;
+    while (true) {
+      for (uint8_t i = 0; i < MAX_MONITORED_CLIENTS; i++) {
+        WiFiClient& client = connectedClients[i];
+        if (client.status() == ESTABLISHED && client.availableForWrite() < (int) a) {
+          a = client.availableForWrite();
+        }
+      }
+      if (a == 0)
+        break;
+      for (uint8_t i = 0; i < MAX_MONITORED_CLIENTS; i++) {
+        if (connectedClients[i].status() == ESTABLISHED) {
+          connectedClients[i].write(buf, a);
+        }
+      }
+      ret += a;
+      if (ret == size)
+        break;
+      buf += a;
+      a = size - ret;
+    }
+    return ret;
+  }
+
+  using Print::write;
+
+  virtual void flush() override {
+    flush(0);
+  }
+
+  virtual void flush(unsigned int maxWaitMs) {
+    for (uint8_t i = 0; i < MAX_MONITORED_CLIENTS; i++) {
+      if (connectedClients[i].status() == ESTABLISHED) {
+        connectedClients[i].flush(maxWaitMs);
+      }
+    }
+  }
+
+  operator bool() {
+    return (TServer::status() == LISTEN);
+  }
+
+  void close() {
+    TServer::stop();
+    for (uint8_t i = 0; i < MAX_MONITORED_CLIENTS; i++) {
+      if (connectedClients[i]) {
+        connectedClients[i].stop();
+      }
+    }
+  }
+  void stop() {close();}
+  void end() {close();}
+
+private:
+  TClient connectedClients[MAX_MONITORED_CLIENTS];
+  uint8_t index = 0;
+
+};
+
+typedef ArduinoComptibleWiFiServerTemplate<WiFiServer, WiFiClient> ArduinoWiFiServer;
+typedef ArduinoComptibleWiFiServerTemplate<WiFiServerSecure, WiFiClientSecure> ArduinoWiFiServerSecure;
+
+#endif