asio: initial idf port of asio library without ssl

* Original commit: espressif/esp-idf@1ef13c524c

components/asio/component.mk

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+COMPONENT_ADD_INCLUDEDIRS := asio/asio/include port/include
+COMPONENT_PRIV_INCLUDEDIRS := private_include
+COMPONENT_SRCDIRS := asio/asio/src
+COMPONENT_OBJEXCLUDE := asio/asio/src/asio_ssl.o
+
+COMPONENT_SUBMODULES += asio

components/asio/port/include/esp_asio_config.h

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+// Copyright 2018 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#ifndef _ESP_ASIO_CONFIG_H_
+#define _ESP_ASIO_CONFIG_H_
+
+//
+// Enabling exceptions only when they are enabled in menuconfig
+//
+# include <sdkconfig.h>
+# ifndef CONFIG_CXX_EXCEPTIONS
+#  define ASIO_NO_EXCEPTIONS
+# endif   // CONFIG_CXX_EXCEPTIONS
+
+//
+// LWIP compatifility inet and address macros/functions
+//
+# define LWIP_COMPAT_SOCKET_INET 1
+# define LWIP_COMPAT_SOCKET_ADDR 1
+
+//
+// Specific ASIO feature flags
+//
+# define ASIO_DISABLE_SERIAL_PORT
+# define ASIO_SEPARATE_COMPILATION
+# define ASIO_STANDALONE
+# define ASIO_NO_TYPEID
+# define ASIO_DISABLE_SIGNAL
+# define ASIO_HAS_PTHREADS
+# define ASIO_DISABLE_EPOLL
+# define ASIO_DISABLE_EVENTFD
+# define ASIO_DISABLE_SIGNAL
+# define ASIO_DISABLE_SIGACTION
+
+#endif // _ESP_ASIO_CONFIG_H_

components/asio/port/include/esp_exception.h

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+
+// Copyright 2018 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#ifndef _ESP_EXCEPTION_H_
+#define _ESP_EXCEPTION_H_
+
+//
+// This exception stub is enabled only if exceptions are disabled in menuconfig
+//
+#if !defined(CONFIG_CXX_EXCEPTIONS) && defined (ASIO_NO_EXCEPTIONS)
+
+#include "esp_log.h"
+
+//
+// asio exception stub
+//
+namespace asio {
+namespace detail {
+template <typename Exception>
+void throw_exception(const Exception& e)
+{
+  ESP_LOGE("esp32_asio_exception", "Caught exception: %s!", e.what());   
+  abort();
+}
+}}
+#endif // CONFIG_CXX_EXCEPTIONS==1 && defined (ASIO_NO_EXCEPTIONS)
+
+#endif // _ESP_EXCEPTION_H_

docs/en/api-reference/protocols/asio.rst

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+ASIO port
+=========
+
+Overview
+--------
+Asio is a cross-platform C++ library, see https://think-async.com. It provides a consistent asynchronous model using a modern C++ approach.
+
+
+ASIO documentation
+^^^^^^^^^^^^^^^^^^
+Please refer to the original asio documentation at https://think-async.com/Asio/Documentation.
+Asio also comes with a number of examples which could be find under Documentation/Examples on that web site.
+
+Supported features
+^^^^^^^^^^^^^^^^^^
+ESP platform port currently supports only network asynchronous socket operations; does not support serial port and ssl.
+Internal asio settings for ESP include
+- EXCEPTIONS: Supported, choice in menuconfig
+- SIGNAL, SIGACTION: Not supported
+- EPOLL, EVENTFD: Not supported
+- TYPEID: Disabled by default, but supported in toolchain and asio (provided stdlib recompiled with -frtti)
+
+Application Example
+-------------------
+ESP examples are based on standard asio examples `examples/protocols/asio`:
+- udp_echo_server
+- tcp_echo_server
+- chat_client
+- chat_server
+Please refer to the specific example README.md for details
+
+

docs/zh_CN/api-reference/protocols/asio.rst

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+.. include:: ../../../en/api-reference/protocols/asio.rst

examples/protocols/asio/chat_client/Makefile

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+#
+# This is a project Makefile. It is assumed the directory this Makefile resides in is a
+# project subdirectory.
+#
+PROJECT_NAME := asio_chatclient
+
+include $(IDF_PATH)/make/project.mk

examples/protocols/asio/chat_client/README.md

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+# ASIO chat server example
+
+Simple asio chat client using WiFi STA
+
+## Example workflow
+
+- WiFi STA is started and trying to connect to the access point defined through `make menuconfig`
+- Once connected and acquired IP address ASIO chat client connects to a corresponding server whose port number and ip are defined through `make menuconfig`
+- Chat client receives all messages from other chat clients, also it sends message received from stdin using `make monitor`
+
+## Running the example
+
+- Run `make menuconfig` to configure the access point's SSID and Password and server ip address and port number
+- Start chat server either on host machine or as another ESP device running chat_server example
+- Run `make flash monitor` to build and upload the example to your board and connect to it's serial terminal
+- Wait for WiFi to connect to your access point
+- Receive and send messages to/from other clients on stdin/stdout via serial terminal.
+
+See the README.md file in the upper level 'examples' directory for more information about examples.

examples/protocols/asio/chat_client/asio_chat_client_test.py

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+import re
+import os
+import sys
+from socket import *
+from threading import Thread
+import time
+
+# this is a test case write with tiny-test-fw.
+# to run test cases outside tiny-test-fw,
+# we need to set environment variable `TEST_FW_PATH`,
+# then get and insert `TEST_FW_PATH` to sys path before import FW module
+test_fw_path = os.getenv("TEST_FW_PATH")
+if test_fw_path and test_fw_path not in sys.path:
+    sys.path.insert(0, test_fw_path)
+
+import TinyFW
+import IDF
+
+global g_client_response;
+global g_msg_to_client;
+
+g_client_response = ""
+g_msg_to_client = "   3XYZ"
+
+def get_my_ip():
+    s1 = socket(AF_INET, SOCK_DGRAM)
+    s1.connect(("8.8.8.8", 80))
+    my_ip = s1.getsockname()[0]
+    s1.close()
+    return my_ip
+
+def chat_server_sketch(my_ip):
+    global g_client_response
+    print("Starting the server on {}".format(my_ip))
+    port=2222
+    s=socket(AF_INET, SOCK_STREAM)
+    s.bind((my_ip, port))
+    s.listen(1)
+    q,addr=s.accept()
+    print("connection accepted")
+    q.send(g_msg_to_client)
+    data = q.recv(1024)
+    # check if received initial empty message
+    if (len(data)>4):
+        g_client_response = data
+    else:
+        g_client_response = q.recv(1024)
+        print("received from client {}".format(g_client_response))
+    s.close()
+    print("server closed")
+
+@IDF.idf_example_test(env_tag="Example_WIFI")
+def test_examples_protocol_asio_chat_client(env, extra_data):
+    """
+    steps: |
+      1. Test to start simple tcp server
+      2. `dut1` joins AP
+      3. Test injects server IP to `dut1`via stdin
+      4. Test evaluates `dut1` receives a message server placed
+      5. Test injects a message to `dut1` to be sent as chat_client message
+      6. Test evaluates received test message in host server
+    """
+    global g_client_response
+    global g_msg_to_client
+    test_msg="ABC"
+    dut1 = env.get_dut("chat_client", "examples/protocols/asio/chat_client")
+    # check and log bin size
+    binary_file = os.path.join(dut1.app.binary_path, "asio_chatclient.bin")
+    bin_size = os.path.getsize(binary_file)
+    IDF.log_performance("asio_chatclient_size", "{}KB".format(bin_size//1024))
+    IDF.check_performance("asio_chatclient_size", bin_size//1024)
+    # 1. start a tcp server on the host
+    host_ip = get_my_ip()
+    thread1 = Thread(target = chat_server_sketch, args = (host_ip,))
+    thread1.start()
+    # 2. start the dut test and wait till client gets IP address
+    dut1.start_app()
+    data = dut1.expect(re.compile(r" sta ip: ([^,]+),"))
+    # 3. send host's IP to the client i.e. the `dut1`
+    dut1.write(host_ip)
+    # 4. client `dut1` should receive a message
+    dut1.expect(g_msg_to_client[4:]) # Strip out the front 4 bytes of message len (see chat_message protocol)
+    # 5. write test message from `dut1` chat_client to the server
+    dut1.write(test_msg)
+    while g_client_response == "":
+        time.sleep(1)
+    print(g_client_response)
+    # 6. evaluate host_server received this message
+    if (g_client_response[4:] == test_msg):
+        print("PASS: Received correct message")
+        pass
+    else:
+        print("Failure!")
+        raise ValueError('Wrong data received from asi tcp server: {} (expected:{})'.format(g_client_response, test_msg))
+    thread1.join()
+
+if __name__ == '__main__':
+    test_examples_protocol_asio_chat_client()

examples/protocols/asio/chat_client/components/component.mk

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+#
+# Component Makefile
+#
+# This Makefile should, at the very least, just include $(SDK_PATH)/Makefile. By default, 
+# this will take the sources in the src/ directory, compile them and link them into 
+# lib(subdirectory_name).a in the build directory. This behaviour is entirely configurable,
+# please read the SDK documents if you need to do this.
+#
+
+COMPONENT_SRCDIRS = .

examples/protocols/asio/chat_client/components/wifi_asio.cpp

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+/* Common WiFi Init as STA for ASIO examples
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/event_groups.h"
+#include "esp_system.h"
+#include "esp_wifi.h"
+#include "esp_event_loop.h"
+#include "esp_log.h"
+#include "nvs_flash.h"
+#include "driver/uart.h"
+#include "esp_console.h"
+#include "esp_vfs_dev.h"
+
+#include "lwip/err.h"
+#include "lwip/sys.h"
+
+#include <cstring>
+
+/* The examples use simple WiFi configuration that you can set via
+   'make menuconfig'.
+
+   If you'd rather not, just change the below entries to strings with
+   the config you want - ie #define EXAMPLE_WIFI_SSID "mywifissid"
+*/
+#define EXAMPLE_ESP_WIFI_SSID      CONFIG_ESP_WIFI_SSID
+#define EXAMPLE_ESP_WIFI_PASS      CONFIG_ESP_WIFI_PASSWORD
+
+/* FreeRTOS event group to signal when we are connected*/
+static EventGroupHandle_t wifi_event_group;
+
+/* The event group allows multiple bits for each event,
+   but we only care about one event - are we connected
+   to the AP with an IP? */
+const int WIFI_CONNECTED_BIT = BIT0;
+
+static const char *TAG = "asio example wifi init";
+
+/**
+ *  Definition of ASIO main method, which is called after network initialized
+ */
+void asio_main();
+
+static esp_err_t event_handler(void *ctx, system_event_t *event)
+{
+    switch(event->event_id) {
+    case SYSTEM_EVENT_STA_START:
+        esp_wifi_connect();
+        break;
+    case SYSTEM_EVENT_STA_GOT_IP:
+        ESP_LOGI(TAG, "got ip:%s",
+                 ip4addr_ntoa(&event->event_info.got_ip.ip_info.ip));
+        xEventGroupSetBits(wifi_event_group, WIFI_CONNECTED_BIT);
+        break;
+    case SYSTEM_EVENT_AP_STACONNECTED:
+        ESP_LOGI(TAG, "station:" MACSTR " join, AID=%d",
+                 MAC2STR(event->event_info.sta_connected.mac),
+                 event->event_info.sta_connected.aid);
+        break;
+    case SYSTEM_EVENT_AP_STADISCONNECTED:
+        ESP_LOGI(TAG, "station:" MACSTR "leave, AID=%d",
+                 MAC2STR(event->event_info.sta_disconnected.mac),
+                 event->event_info.sta_disconnected.aid);
+        break;
+    case SYSTEM_EVENT_STA_DISCONNECTED:
+        esp_wifi_connect();
+        xEventGroupClearBits(wifi_event_group, WIFI_CONNECTED_BIT);
+        break;
+    default:
+        break;
+    }
+    return ESP_OK;
+}
+
+void wifi_init_sta()
+{
+    wifi_event_group = xEventGroupCreate();
+
+    tcpip_adapter_init();
+    ESP_ERROR_CHECK(esp_event_loop_init(event_handler, NULL) );
+
+    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
+    ESP_ERROR_CHECK(esp_wifi_init(&cfg));
+    wifi_config_t wifi_config;
+    // zero out the config struct to ensure defaults are setup
+    memset(&wifi_config, 0, sizeof(wifi_sta_config_t));
+    // only copy ssid&password from example config
+    strcpy((char*)(wifi_config.sta.ssid), EXAMPLE_ESP_WIFI_SSID);
+    strcpy((char*)(wifi_config.sta.password), EXAMPLE_ESP_WIFI_PASS);
+
+    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA) );
+    ESP_ERROR_CHECK(esp_wifi_set_config(ESP_IF_WIFI_STA, &wifi_config) );
+    ESP_ERROR_CHECK(esp_wifi_start() );
+
+    ESP_LOGI(TAG, "wifi_init_sta finished.");
+    ESP_LOGI(TAG, "connect to ap SSID:%s password:%s",
+             EXAMPLE_ESP_WIFI_SSID, EXAMPLE_ESP_WIFI_PASS);
+}
+
+extern "C" void app_main()
+{
+    //Initialize NVS
+    esp_err_t ret = nvs_flash_init();
+    if (ret == ESP_ERR_NVS_NO_FREE_PAGES) {
+      ESP_ERROR_CHECK(nvs_flash_erase());
+      ret = nvs_flash_init();
+    }
+    ESP_ERROR_CHECK(ret);
+    
+    ESP_LOGI(TAG, "ESP_WIFI_MODE_AP");
+    wifi_init_sta();
+
+    // Initialize VFS & UART so we can use std::cout/cin
+    setvbuf(stdin, NULL, _IONBF, 0);
+    setvbuf(stdout, NULL, _IONBF, 0);
+    /* Install UART driver for interrupt-driven reads and writes */
+    ESP_ERROR_CHECK( uart_driver_install( (uart_port_t)CONFIG_CONSOLE_UART_NUM,
+            256, 0, 0, NULL, 0) );
+    /* Tell VFS to use UART driver */
+    esp_vfs_dev_uart_use_driver(CONFIG_CONSOLE_UART_NUM);
+    esp_vfs_dev_uart_set_rx_line_endings(ESP_LINE_ENDINGS_CR);
+    /* Move the caret to the beginning of the next line on '\n' */
+    esp_vfs_dev_uart_set_tx_line_endings(ESP_LINE_ENDINGS_CRLF);
+
+    // wait till we receive IP, so asio realated code can be started
+    xEventGroupWaitBits(wifi_event_group, WIFI_CONNECTED_BIT, 1, 1, portMAX_DELAY);
+
+    // network is ready, let's proceed with ASIO example
+    asio_main();
+}

examples/protocols/asio/chat_client/main/Kconfig.projbuild

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+menu "Example Configuration"
+
+config ESP_WIFI_SSID
+    string "WiFi SSID"
+    default "myssid"
+    help
+	SSID (network name) for the example to connect to.
+
+config ESP_WIFI_PASSWORD
+    string "WiFi Password"
+    default "mypassword"
+    help
+	WiFi password (WPA or WPA2) for the example to use.
+
+config EXAMPLE_PORT
+    string "asio example port number"
+    default "2222"
+    help
+    Port number used by ASIO example
+
+config EXAMPLE_SERVER_IP
+    string "asio example server ip for this client to connect to (leave defalut=FROM_STDIN to enter the server address via serial terminal)"
+    default "FROM_STDIN"
+    help
+    Please set the host name or ip address of corespondant server running
+
+endmenu

examples/protocols/asio/chat_client/main/chat_client.cpp

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+//
+// chat_client.cpp
+// ~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstdlib>
+#include <deque>
+#include <iostream>
+#include <thread>
+#include "asio.hpp"
+#include "chat_message.hpp"
+
+using asio::ip::tcp;
+
+typedef std::deque<chat_message> chat_message_queue;
+
+class chat_client
+{
+public:
+  chat_client(asio::io_context& io_context,
+      const tcp::resolver::results_type& endpoints)
+    : io_context_(io_context),
+      socket_(io_context)
+  {
+    do_connect(endpoints);
+  }
+
+  void write(const chat_message& msg)
+  {
+    asio::post(io_context_,
+        [this, msg]()
+        {
+          bool write_in_progress = !write_msgs_.empty();
+          write_msgs_.push_back(msg);
+          if (!write_in_progress)
+          {
+            do_write();
+          }
+        });
+  }
+
+  void close()
+  {
+    asio::post(io_context_, [this]() { socket_.close(); });
+  }
+
+private:
+  void do_connect(const tcp::resolver::results_type& endpoints)
+  {
+    asio::async_connect(socket_, endpoints,
+        [this](std::error_code ec, tcp::endpoint)
+        {
+          if (!ec)
+          {
+            do_read_header();
+          }
+        });
+  }
+
+  void do_read_header()
+  {
+    asio::async_read(socket_,
+        asio::buffer(read_msg_.data(), chat_message::header_length),
+        [this](std::error_code ec, std::size_t /*length*/)
+        {
+          if (!ec && read_msg_.decode_header())
+          {
+            do_read_body();
+          }
+          else
+          {
+            socket_.close();
+          }
+        });
+  }
+
+  void do_read_body()
+  {
+    asio::async_read(socket_,
+        asio::buffer(read_msg_.body(), read_msg_.body_length()),
+        [this](std::error_code ec, std::size_t /*length*/)
+        {
+          if (!ec)
+          {
+            std::cout.write(read_msg_.body(), read_msg_.body_length());
+            std::cout << "\n";
+            do_read_header();
+          }
+          else
+          {
+            socket_.close();
+          }
+        });
+  }
+
+  void do_write()
+  {
+    asio::async_write(socket_,
+        asio::buffer(write_msgs_.front().data(),
+          write_msgs_.front().length()),
+        [this](std::error_code ec, std::size_t /*length*/)
+        {
+          if (!ec)
+          {
+            write_msgs_.pop_front();
+            if (!write_msgs_.empty())
+            {
+              do_write();
+            }
+          }
+          else
+          {
+            socket_.close();
+          }
+        });
+  }
+
+private:
+  asio::io_context& io_context_;
+  tcp::socket socket_;
+  chat_message read_msg_;
+  chat_message_queue write_msgs_;
+};
+
+void read_line(char * line, int max_chars);
+
+
+void asio_main()
+{
+    std::string name(CONFIG_EXAMPLE_SERVER_IP);
+    std::string port(CONFIG_EXAMPLE_PORT);
+    char line[chat_message::max_body_length + 1] = { 0 };
+
+    if (name == "FROM_STDIN") {
+      std::cout << "Please enter ip address of chat server" << std::endl;
+      if (std::cin.getline(line, chat_message::max_body_length + 1)) {
+        name = line;
+        std::cout << "Chat server IP:" << name << std::endl;
+      }
+    }
+
+    asio::io_context io_context;
+    tcp::resolver resolver(io_context);
+    auto endpoints = resolver.resolve(name, port);
+
+    chat_client c(io_context, endpoints);
+
+    std::thread t([&io_context](){ io_context.run(); });
+
+    while (std::cin.getline(line, chat_message::max_body_length + 1) && std::string(line) != "exit\n") {
+      chat_message msg;
+      msg.body_length(std::strlen(line));
+      std::memcpy(msg.body(), line, msg.body_length());
+      msg.encode_header();
+      c.write(msg);
+    }
+
+    c.close();
+    t.join();
+}

examples/protocols/asio/chat_client/main/chat_message.hpp

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+//
+// chat_message.hpp
+// ~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef CHAT_MESSAGE_HPP
+#define CHAT_MESSAGE_HPP
+
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+class chat_message
+{
+public:
+  enum { header_length = 4 };
+  enum { max_body_length = 512 };
+
+  chat_message()
+    : body_length_(0)
+  {
+  }
+
+  const char* data() const
+  {
+    return data_;
+  }
+
+  char* data()
+  {
+    return data_;
+  }
+
+  std::size_t length() const
+  {
+    return header_length + body_length_;
+  }
+
+  const char* body() const
+  {
+    return data_ + header_length;
+  }
+
+  char* body()
+  {
+    return data_ + header_length;
+  }
+
+  std::size_t body_length() const
+  {
+    return body_length_;
+  }
+
+  void body_length(std::size_t new_length)
+  {
+    body_length_ = new_length;
+    if (body_length_ > max_body_length)
+      body_length_ = max_body_length;
+  }
+
+  bool decode_header()
+  {
+    char header[header_length + 1] = "";
+    std::strncat(header, data_, header_length);
+    body_length_ = std::atoi(header);
+    if (body_length_ > max_body_length)
+    {
+      body_length_ = 0;
+      return false;
+    }
+    return true;
+  }
+
+  void encode_header()
+  {
+    char header[header_length + 1] = "";
+    std::sprintf(header, "%4d", static_cast<int>(body_length_));
+    std::memcpy(data_, header, header_length);
+  }
+
+private:
+  char data_[header_length + max_body_length];
+  std::size_t body_length_;
+};
+
+#endif // CHAT_MESSAGE_HPP

examples/protocols/asio/chat_client/main/component.mk

@@ -0,0 +1,8 @@
+#
+# Main component makefile.
+#
+# This Makefile can be left empty. By default, it will take the sources in the 
+# src/ directory, compile them and link them into lib(subdirectory_name).a 
+# in the build directory. This behaviour is entirely configurable,
+# please read the ESP-IDF documents if you need to do this.
+#

examples/protocols/asio/chat_client/sdkconfig.defaults

@@ -0,0 +1 @@
+CONFIG_MAIN_TASK_STACK_SIZE=8192

examples/protocols/asio/chat_server/Makefile

@@ -0,0 +1,7 @@
+#
+# This is a project Makefile. It is assumed the directory this Makefile resides in is a
+# project subdirectory.
+#
+PROJECT_NAME := asio_chatserver
+
+include $(IDF_PATH)/make/project.mk

examples/protocols/asio/chat_server/README.md

@@ -0,0 +1,22 @@
+# ASIO chat server example
+
+Simple asio chat server using WiFi STA
+
+## Example workflow
+
+- WiFi STA is started and trying to connect to the access point defined through `make menuconfig`
+- Once connected and acquired IP address, ASIO chat server is started on port number defined through `make menuconfig`
+- Chat server echoes a message (received from any client) to all connected clients
+
+## Running the example
+
+- Run `make menuconfig` to configure the access point's SSID and Password and port number
+- Run `make flash monitor` to build and upload the example to your board and connect to it's serial terminal
+- Wait for WiFi to connect to your access point (note the IP address)
+- Connect to the server using multiple clients, for example using any option below
+    - build and run asi chat client on your host machine
+    - run chat_client asio example on ESP platform
+    - since chat message consist of ascii size and message, it is possible to 
+        netcat `nc IP PORT` and type for example `   4ABC<CR>` to transmit 'ABC\n'
+
+See the README.md file in the upper level 'examples' directory for more information about examples.

examples/protocols/asio/chat_server/asio_chat_server_test.py

@@ -0,0 +1,56 @@
+import re
+import os
+import sys
+from socket import *
+
+
+# this is a test case write with tiny-test-fw.
+# to run test cases outside tiny-test-fw,
+# we need to set environment variable `TEST_FW_PATH`,
+# then get and insert `TEST_FW_PATH` to sys path before import FW module
+test_fw_path = os.getenv("TEST_FW_PATH")
+if test_fw_path and test_fw_path not in sys.path:
+    sys.path.insert(0, test_fw_path)
+
+import TinyFW
+import IDF
+
+
+
+
+@IDF.idf_example_test(env_tag="Example_WIFI")
+def test_examples_protocol_asio_chat_server(env, extra_data):
+    """
+    steps: |
+      1. join AP
+      2. Start server
+      3. Test connects to server and sends a test message
+      4. Test evaluates received test message from server
+    """
+    test_msg="   4ABC\n"
+    dut1 = env.get_dut("chat_server", "examples/protocols/asio/chat_server")
+    # check and log bin size
+    binary_file = os.path.join(dut1.app.binary_path, "asio_chatserver.bin")
+    bin_size = os.path.getsize(binary_file)
+    IDF.log_performance("asio_chatserver_bin_size", "{}KB".format(bin_size//1024))
+    IDF.check_performance("asio_chatserver_size", bin_size//1024)
+    # 1. start test
+    dut1.start_app()
+    # 2. get the server IP address
+    data = dut1.expect(re.compile(r" sta ip: ([^,]+),"))
+    # 3. create tcp client and connect to server
+    cli = socket(AF_INET,SOCK_STREAM)
+    cli.connect((data[0],80))
+    cli.send(test_msg)
+    data = cli.recv(1024)
+    # 4. check the message received back from the server
+    if (data == test_msg):
+        print("PASS: Received correct message {}".format(data))
+        pass
+    else:
+        print("Failure!")
+        raise ValueError('Wrong data received from asi tcp server: {} (expoected:{})'.format(data, test_msg))
+
+
+if __name__ == '__main__':
+    test_examples_protocol_asio_chat_server()

examples/protocols/asio/chat_server/components/component.mk

@@ -0,0 +1,10 @@
+#
+# Component Makefile
+#
+# This Makefile should, at the very least, just include $(SDK_PATH)/Makefile. By default, 
+# this will take the sources in the src/ directory, compile them and link them into 
+# lib(subdirectory_name).a in the build directory. This behaviour is entirely configurable,
+# please read the SDK documents if you need to do this.
+#
+
+COMPONENT_SRCDIRS = .

examples/protocols/asio/chat_server/components/wifi_asio.cpp

@@ -0,0 +1,136 @@
+/* Common WiFi Init as STA for ASIO examples
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/event_groups.h"
+#include "esp_system.h"
+#include "esp_wifi.h"
+#include "esp_event_loop.h"
+#include "esp_log.h"
+#include "nvs_flash.h"
+#include "driver/uart.h"
+#include "esp_console.h"
+#include "esp_vfs_dev.h"
+
+#include "lwip/err.h"
+#include "lwip/sys.h"
+
+#include <cstring>
+
+/* The examples use simple WiFi configuration that you can set via
+   'make menuconfig'.
+
+   If you'd rather not, just change the below entries to strings with
+   the config you want - ie #define EXAMPLE_WIFI_SSID "mywifissid"
+*/
+#define EXAMPLE_ESP_WIFI_SSID      CONFIG_ESP_WIFI_SSID
+#define EXAMPLE_ESP_WIFI_PASS      CONFIG_ESP_WIFI_PASSWORD
+
+/* FreeRTOS event group to signal when we are connected*/
+static EventGroupHandle_t wifi_event_group;
+
+/* The event group allows multiple bits for each event,
+   but we only care about one event - are we connected
+   to the AP with an IP? */
+const int WIFI_CONNECTED_BIT = BIT0;
+
+static const char *TAG = "asio example wifi init";
+
+/**
+ *  Definition of ASIO main method, which is called after network initialized
+ */
+void asio_main();
+
+static esp_err_t event_handler(void *ctx, system_event_t *event)
+{
+    switch(event->event_id) {
+    case SYSTEM_EVENT_STA_START:
+        esp_wifi_connect();
+        break;
+    case SYSTEM_EVENT_STA_GOT_IP:
+        ESP_LOGI(TAG, "got ip:%s",
+                 ip4addr_ntoa(&event->event_info.got_ip.ip_info.ip));
+        xEventGroupSetBits(wifi_event_group, WIFI_CONNECTED_BIT);
+        break;
+    case SYSTEM_EVENT_AP_STACONNECTED:
+        ESP_LOGI(TAG, "station:" MACSTR " join, AID=%d",
+                 MAC2STR(event->event_info.sta_connected.mac),
+                 event->event_info.sta_connected.aid);
+        break;
+    case SYSTEM_EVENT_AP_STADISCONNECTED:
+        ESP_LOGI(TAG, "station:" MACSTR "leave, AID=%d",
+                 MAC2STR(event->event_info.sta_disconnected.mac),
+                 event->event_info.sta_disconnected.aid);
+        break;
+    case SYSTEM_EVENT_STA_DISCONNECTED:
+        esp_wifi_connect();
+        xEventGroupClearBits(wifi_event_group, WIFI_CONNECTED_BIT);
+        break;
+    default:
+        break;
+    }
+    return ESP_OK;
+}
+
+void wifi_init_sta()
+{
+    wifi_event_group = xEventGroupCreate();
+
+    tcpip_adapter_init();
+    ESP_ERROR_CHECK(esp_event_loop_init(event_handler, NULL) );
+
+    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
+    ESP_ERROR_CHECK(esp_wifi_init(&cfg));
+    wifi_config_t wifi_config;
+    // zero out the config struct to ensure defaults are setup
+    memset(&wifi_config, 0, sizeof(wifi_sta_config_t));
+    // only copy ssid&password from example config
+    strcpy((char*)(wifi_config.sta.ssid), EXAMPLE_ESP_WIFI_SSID);
+    strcpy((char*)(wifi_config.sta.password), EXAMPLE_ESP_WIFI_PASS);
+
+    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA) );
+    ESP_ERROR_CHECK(esp_wifi_set_config(ESP_IF_WIFI_STA, &wifi_config) );
+    ESP_ERROR_CHECK(esp_wifi_start() );
+
+    ESP_LOGI(TAG, "wifi_init_sta finished.");
+    ESP_LOGI(TAG, "connect to ap SSID:%s password:%s",
+             EXAMPLE_ESP_WIFI_SSID, EXAMPLE_ESP_WIFI_PASS);
+}
+
+extern "C" void app_main()
+{
+    //Initialize NVS
+    esp_err_t ret = nvs_flash_init();
+    if (ret == ESP_ERR_NVS_NO_FREE_PAGES) {
+      ESP_ERROR_CHECK(nvs_flash_erase());
+      ret = nvs_flash_init();
+    }
+    ESP_ERROR_CHECK(ret);
+    
+    ESP_LOGI(TAG, "ESP_WIFI_MODE_AP");
+    wifi_init_sta();
+
+    // Initialize VFS & UART so we can use std::cout/cin
+    setvbuf(stdin, NULL, _IONBF, 0);
+    setvbuf(stdout, NULL, _IONBF, 0);
+    /* Install UART driver for interrupt-driven reads and writes */
+    ESP_ERROR_CHECK( uart_driver_install( (uart_port_t)CONFIG_CONSOLE_UART_NUM,
+            256, 0, 0, NULL, 0) );
+    /* Tell VFS to use UART driver */
+    esp_vfs_dev_uart_use_driver(CONFIG_CONSOLE_UART_NUM);
+    esp_vfs_dev_uart_set_rx_line_endings(ESP_LINE_ENDINGS_CR);
+    /* Move the caret to the beginning of the next line on '\n' */
+    esp_vfs_dev_uart_set_tx_line_endings(ESP_LINE_ENDINGS_CRLF);
+
+    // wait till we receive IP, so asio realated code can be started
+    xEventGroupWaitBits(wifi_event_group, WIFI_CONNECTED_BIT, 1, 1, portMAX_DELAY);
+
+    // network is ready, let's proceed with ASIO example
+    asio_main();
+}

examples/protocols/asio/chat_server/main/Kconfig.projbuild

@@ -0,0 +1,21 @@
+menu "Example Configuration"
+
+config ESP_WIFI_SSID
+    string "WiFi SSID"
+    default "myssid"
+    help
+	SSID (network name) for the example to connect to.
+
+config ESP_WIFI_PASSWORD
+    string "WiFi Password"
+    default "mypassword"
+    help
+	WiFi password (WPA or WPA2) for the example to use.
+
+config EXAMPLE_PORT
+    string "asio example port number"
+    default "80"
+    help
+    Port number used by ASIO example
+
+endmenu

examples/protocols/asio/chat_server/main/chat_message.hpp

@@ -0,0 +1,91 @@
+//
+// chat_message.hpp
+// ~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef CHAT_MESSAGE_HPP
+#define CHAT_MESSAGE_HPP
+
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+class chat_message
+{
+public:
+  enum { header_length = 4 };
+  enum { max_body_length = 512 };
+
+  chat_message()
+    : body_length_(0)
+  {
+  }
+
+  const char* data() const
+  {
+    return data_;
+  }
+
+  char* data()
+  {
+    return data_;
+  }
+
+  std::size_t length() const
+  {
+    return header_length + body_length_;
+  }
+
+  const char* body() const
+  {
+    return data_ + header_length;
+  }
+
+  char* body()
+  {
+    return data_ + header_length;
+  }
+
+  std::size_t body_length() const
+  {
+    return body_length_;
+  }
+
+  void body_length(std::size_t new_length)
+  {
+    body_length_ = new_length;
+    if (body_length_ > max_body_length)
+      body_length_ = max_body_length;
+  }
+
+  bool decode_header()
+  {
+    char header[header_length + 1] = "";
+    std::strncat(header, data_, header_length);
+    body_length_ = std::atoi(header);
+    if (body_length_ > max_body_length)
+    {
+      body_length_ = 0;
+      return false;
+    }
+    return true;
+  }
+
+  void encode_header()
+  {
+    char header[header_length + 1] = "";
+    std::sprintf(header, "%4d", static_cast<int>(body_length_));
+    std::memcpy(data_, header, header_length);
+  }
+
+private:
+  char data_[header_length + max_body_length];
+  std::size_t body_length_;
+};
+
+#endif // CHAT_MESSAGE_HPP

examples/protocols/asio/chat_server/main/chat_server.cpp

@@ -0,0 +1,214 @@
+//
+// chat_server.cpp
+// ~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstdlib>
+#include <deque>
+#include <iostream>
+#include <list>
+#include <memory>
+#include <set>
+#include <utility>
+#include "asio.hpp"
+#include "chat_message.hpp"
+
+using asio::ip::tcp;
+
+//----------------------------------------------------------------------
+
+typedef std::deque<chat_message> chat_message_queue;
+
+//----------------------------------------------------------------------
+
+class chat_participant
+{
+public:
+  virtual ~chat_participant() {}
+  virtual void deliver(const chat_message& msg) = 0;
+};
+
+typedef std::shared_ptr<chat_participant> chat_participant_ptr;
+
+//----------------------------------------------------------------------
+
+class chat_room
+{
+public:
+  void join(chat_participant_ptr participant)
+  {
+    participants_.insert(participant);
+    for (auto msg: recent_msgs_)
+      participant->deliver(msg);
+  }
+
+  void leave(chat_participant_ptr participant)
+  {
+    participants_.erase(participant);
+  }
+
+  void deliver(const chat_message& msg)
+  {
+    recent_msgs_.push_back(msg);
+    while (recent_msgs_.size() > max_recent_msgs)
+      recent_msgs_.pop_front();
+
+    for (auto participant: participants_)
+      participant->deliver(msg);
+  }
+
+private:
+  std::set<chat_participant_ptr> participants_;
+  enum { max_recent_msgs = 100 };
+  chat_message_queue recent_msgs_;
+};
+
+//----------------------------------------------------------------------
+
+class chat_session
+  : public chat_participant,
+    public std::enable_shared_from_this<chat_session>
+{
+public:
+  chat_session(tcp::socket socket, chat_room& room)
+    : socket_(std::move(socket)),
+      room_(room)
+  {
+  }
+
+  void start()
+  {
+    room_.join(shared_from_this());
+    do_read_header();
+  }
+
+  void deliver(const chat_message& msg)
+  {
+    bool write_in_progress = !write_msgs_.empty();
+    write_msgs_.push_back(msg);
+    if (!write_in_progress)
+    {
+      do_write();
+    }
+  }
+
+private:
+  void do_read_header()
+  {
+    auto self(shared_from_this());
+    asio::async_read(socket_,
+        asio::buffer(read_msg_.data(), chat_message::header_length),
+        [this, self](std::error_code ec, std::size_t /*length*/)
+        {
+          if (!ec && read_msg_.decode_header())
+          {
+            do_read_body();
+          }
+          else
+          {
+            room_.leave(shared_from_this());
+          }
+        });
+  }
+
+  void do_read_body()
+  {
+    auto self(shared_from_this());
+    asio::async_read(socket_,
+        asio::buffer(read_msg_.body(), read_msg_.body_length()),
+        [this, self](std::error_code ec, std::size_t /*length*/)
+        {
+          if (!ec)
+          {
+            room_.deliver(read_msg_);
+            do_read_header();
+          }
+          else
+          {
+            room_.leave(shared_from_this());
+          }
+        });
+  }
+
+  void do_write()
+  {
+    auto self(shared_from_this());
+    asio::async_write(socket_,
+        asio::buffer(write_msgs_.front().data(),
+          write_msgs_.front().length()),
+        [this, self](std::error_code ec, std::size_t /*length*/)
+        {
+          if (!ec)
+          {
+            write_msgs_.pop_front();
+            if (!write_msgs_.empty())
+            {
+              do_write();
+            }
+          }
+          else
+          {
+            room_.leave(shared_from_this());
+          }
+        });
+  }
+
+  tcp::socket socket_;
+  chat_room& room_;
+  chat_message read_msg_;
+  chat_message_queue write_msgs_;
+};
+
+//----------------------------------------------------------------------
+
+class chat_server
+{
+public:
+  chat_server(asio::io_context& io_context,
+      const tcp::endpoint& endpoint)
+    : acceptor_(io_context, endpoint)
+  {
+    do_accept();
+  }
+
+private:
+  void do_accept()
+  {
+    acceptor_.async_accept(
+        [this](std::error_code ec, tcp::socket socket)
+        {
+          if (!ec)
+          {
+            std::make_shared<chat_session>(std::move(socket), room_)->start();
+          }
+
+          do_accept();
+        });
+  }
+
+  tcp::acceptor acceptor_;
+  chat_room room_;
+};
+
+//----------------------------------------------------------------------
+
+int asio_main()
+{
+    asio::io_context io_context;
+
+    std::list<chat_server> servers;
+
+    {
+      tcp::endpoint endpoint(tcp::v4(), std::atoi(CONFIG_EXAMPLE_PORT));
+      servers.emplace_back(io_context, endpoint);
+    }
+
+    io_context.run();
+
+  return 0;
+}

examples/protocols/asio/chat_server/main/component.mk

@@ -0,0 +1,8 @@
+#
+# Main component makefile.
+#
+# This Makefile can be left empty. By default, it will take the sources in the 
+# src/ directory, compile them and link them into lib(subdirectory_name).a 
+# in the build directory. This behaviour is entirely configurable,
+# please read the ESP-IDF documents if you need to do this.
+#

examples/protocols/asio/chat_server/sdkconfig.defaults

@@ -0,0 +1 @@
+CONFIG_MAIN_TASK_STACK_SIZE=8192

examples/protocols/asio/tcp_echo_server/Makefile

@@ -0,0 +1,7 @@
+#
+# This is a project Makefile. It is assumed the directory this Makefile resides in is a
+# project subdirectory.
+#
+PROJECT_NAME := asio_tcp_echoserver
+
+include $(IDF_PATH)/make/project.mk

examples/protocols/asio/tcp_echo_server/README.md

@@ -0,0 +1,18 @@
+# ASIO tcp echo server example
+
+Simple asio echo server using WiFi STA
+
+## Example workflow
+
+- WiFi STA is started and trying to connect to the access point defined through `make menuconfig`
+- Once connected and acquired IP address, ASIO tcp server is started on port number defined through `make menuconfig`
+- Server receives and echoes back messages transmitted from client
+
+## Running the example
+
+- Run `make menuconfig` to configure the access point's SSID and Password and port number
+- Run `make flash monitor` to build and upload the example to your board and connect to it's serial terminal
+- Wait for WiFi to connect to your access point (note the IP address)
+- You can now send a tcp message and check it is repeated, for example using netcat `nc IP PORT`
+
+See the README.md file in the upper level 'examples' directory for more information about examples.

examples/protocols/asio/tcp_echo_server/asio_tcp_server_test.py

@@ -0,0 +1,59 @@
+import re
+import os
+import sys
+from socket import *
+
+
+# this is a test case write with tiny-test-fw.
+# to run test cases outside tiny-test-fw,
+# we need to set environment variable `TEST_FW_PATH`,
+# then get and insert `TEST_FW_PATH` to sys path before import FW module
+test_fw_path = os.getenv("TEST_FW_PATH")
+if test_fw_path and test_fw_path not in sys.path:
+    sys.path.insert(0, test_fw_path)
+
+import TinyFW
+import IDF
+
+
+
+
+@IDF.idf_example_test(env_tag="Example_WIFI")
+def test_examples_protocol_asio_tcp_server(env, extra_data):
+    """
+    steps: |
+      1. join AP
+      2. Start server
+      3. Test connects to server and sends a test message
+      4. Test evaluates received test message from server
+      5. Test evaluates received test message on server stdout
+    """
+    test_msg="echo message from client to server"
+    dut1 = env.get_dut("tcp_echo_server", "examples/protocols/asio/tcp_echo_server")
+    # check and log bin size
+    binary_file = os.path.join(dut1.app.binary_path, "asio_tcp_echoserver.bin")
+    bin_size = os.path.getsize(binary_file)
+    IDF.log_performance("asio_tcp_echoserver_bin_size", "{}KB".format(bin_size//1024))
+    IDF.check_performance("asio_tcp_echoserver_size", bin_size//1024)
+    # 1. start test
+    dut1.start_app()
+    # 2. get the server IP address
+    data = dut1.expect(re.compile(r" sta ip: ([^,]+),"))
+    # 3. create tcp client and connect to server
+    cli = socket(AF_INET,SOCK_STREAM)
+    cli.connect((data[0],80))
+    cli.send(test_msg)
+    data = cli.recv(1024)
+    # 4. check the message received back from the server
+    if (data == test_msg):
+        print("PASS: Received correct message")
+        pass
+    else:
+        print("Failure!")
+        raise ValueError('Wrong data received from asi tcp server: {} (expoected:{})'.format(data, test_msg))
+    # 5. check the client message appears also on server terminal
+    dut1.expect(test_msg)
+
+
+if __name__ == '__main__':
+    test_examples_protocol_asio_tcp_server()

examples/protocols/asio/tcp_echo_server/components/component.mk

@@ -0,0 +1,10 @@
+#
+# Component Makefile
+#
+# This Makefile should, at the very least, just include $(SDK_PATH)/Makefile. By default, 
+# this will take the sources in the src/ directory, compile them and link them into 
+# lib(subdirectory_name).a in the build directory. This behaviour is entirely configurable,
+# please read the SDK documents if you need to do this.
+#
+
+COMPONENT_SRCDIRS = .

examples/protocols/asio/tcp_echo_server/components/wifi_asio.cpp

@@ -0,0 +1,136 @@
+/* Common WiFi Init as STA for ASIO examples
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/event_groups.h"
+#include "esp_system.h"
+#include "esp_wifi.h"
+#include "esp_event_loop.h"
+#include "esp_log.h"
+#include "nvs_flash.h"
+#include "driver/uart.h"
+#include "esp_console.h"
+#include "esp_vfs_dev.h"
+
+#include "lwip/err.h"
+#include "lwip/sys.h"
+
+#include <cstring>
+
+/* The examples use simple WiFi configuration that you can set via
+   'make menuconfig'.
+
+   If you'd rather not, just change the below entries to strings with
+   the config you want - ie #define EXAMPLE_WIFI_SSID "mywifissid"
+*/
+#define EXAMPLE_ESP_WIFI_SSID      CONFIG_ESP_WIFI_SSID
+#define EXAMPLE_ESP_WIFI_PASS      CONFIG_ESP_WIFI_PASSWORD
+
+/* FreeRTOS event group to signal when we are connected*/
+static EventGroupHandle_t wifi_event_group;
+
+/* The event group allows multiple bits for each event,
+   but we only care about one event - are we connected
+   to the AP with an IP? */
+const int WIFI_CONNECTED_BIT = BIT0;
+
+static const char *TAG = "asio example wifi init";
+
+/**
+ *  Definition of ASIO main method, which is called after network initialized
+ */
+void asio_main();
+
+static esp_err_t event_handler(void *ctx, system_event_t *event)
+{
+    switch(event->event_id) {
+    case SYSTEM_EVENT_STA_START:
+        esp_wifi_connect();
+        break;
+    case SYSTEM_EVENT_STA_GOT_IP:
+        ESP_LOGI(TAG, "got ip:%s",
+                 ip4addr_ntoa(&event->event_info.got_ip.ip_info.ip));
+        xEventGroupSetBits(wifi_event_group, WIFI_CONNECTED_BIT);
+        break;
+    case SYSTEM_EVENT_AP_STACONNECTED:
+        ESP_LOGI(TAG, "station:" MACSTR " join, AID=%d",
+                 MAC2STR(event->event_info.sta_connected.mac),
+                 event->event_info.sta_connected.aid);
+        break;
+    case SYSTEM_EVENT_AP_STADISCONNECTED:
+        ESP_LOGI(TAG, "station:" MACSTR "leave, AID=%d",
+                 MAC2STR(event->event_info.sta_disconnected.mac),
+                 event->event_info.sta_disconnected.aid);
+        break;
+    case SYSTEM_EVENT_STA_DISCONNECTED:
+        esp_wifi_connect();
+        xEventGroupClearBits(wifi_event_group, WIFI_CONNECTED_BIT);
+        break;
+    default:
+        break;
+    }
+    return ESP_OK;
+}
+
+void wifi_init_sta()
+{
+    wifi_event_group = xEventGroupCreate();
+
+    tcpip_adapter_init();
+    ESP_ERROR_CHECK(esp_event_loop_init(event_handler, NULL) );
+
+    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
+    ESP_ERROR_CHECK(esp_wifi_init(&cfg));
+    wifi_config_t wifi_config;
+    // zero out the config struct to ensure defaults are setup
+    memset(&wifi_config, 0, sizeof(wifi_sta_config_t));
+    // only copy ssid&password from example config
+    strcpy((char*)(wifi_config.sta.ssid), EXAMPLE_ESP_WIFI_SSID);
+    strcpy((char*)(wifi_config.sta.password), EXAMPLE_ESP_WIFI_PASS);
+
+    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA) );
+    ESP_ERROR_CHECK(esp_wifi_set_config(ESP_IF_WIFI_STA, &wifi_config) );
+    ESP_ERROR_CHECK(esp_wifi_start() );
+
+    ESP_LOGI(TAG, "wifi_init_sta finished.");
+    ESP_LOGI(TAG, "connect to ap SSID:%s password:%s",
+             EXAMPLE_ESP_WIFI_SSID, EXAMPLE_ESP_WIFI_PASS);
+}
+
+extern "C" void app_main()
+{
+    //Initialize NVS
+    esp_err_t ret = nvs_flash_init();
+    if (ret == ESP_ERR_NVS_NO_FREE_PAGES) {
+      ESP_ERROR_CHECK(nvs_flash_erase());
+      ret = nvs_flash_init();
+    }
+    ESP_ERROR_CHECK(ret);
+    
+    ESP_LOGI(TAG, "ESP_WIFI_MODE_AP");
+    wifi_init_sta();
+
+    // Initialize VFS & UART so we can use std::cout/cin
+    setvbuf(stdin, NULL, _IONBF, 0);
+    setvbuf(stdout, NULL, _IONBF, 0);
+    /* Install UART driver for interrupt-driven reads and writes */
+    ESP_ERROR_CHECK( uart_driver_install( (uart_port_t)CONFIG_CONSOLE_UART_NUM,
+            256, 0, 0, NULL, 0) );
+    /* Tell VFS to use UART driver */
+    esp_vfs_dev_uart_use_driver(CONFIG_CONSOLE_UART_NUM);
+    esp_vfs_dev_uart_set_rx_line_endings(ESP_LINE_ENDINGS_CR);
+    /* Move the caret to the beginning of the next line on '\n' */
+    esp_vfs_dev_uart_set_tx_line_endings(ESP_LINE_ENDINGS_CRLF);
+
+    // wait till we receive IP, so asio realated code can be started
+    xEventGroupWaitBits(wifi_event_group, WIFI_CONNECTED_BIT, 1, 1, portMAX_DELAY);
+
+    // network is ready, let's proceed with ASIO example
+    asio_main();
+}

examples/protocols/asio/tcp_echo_server/main/Kconfig.projbuild

@@ -0,0 +1,21 @@
+menu "Example Configuration"
+
+config ESP_WIFI_SSID
+    string "WiFi SSID"
+    default "myssid"
+    help
+	SSID (network name) for the example to connect to.
+
+config ESP_WIFI_PASSWORD
+    string "WiFi Password"
+    default "mypassword"
+    help
+	WiFi password (WPA or WPA2) for the example to use.
+
+config EXAMPLE_PORT
+    string "asio example port number"
+    default "80"
+    help
+    Port number used by ASIO example
+
+endmenu

examples/protocols/asio/tcp_echo_server/main/component.mk

@@ -0,0 +1,9 @@
+#
+# Main component makefile.
+#
+# This Makefile can be left empty. By default, it will take the sources in the 
+# src/ directory, compile them and link them into lib(subdirectory_name).a 
+# in the build directory. This behaviour is entirely configurable,
+# please read the ESP-IDF documents if you need to do this.
+#
+

examples/protocols/asio/tcp_echo_server/main/echo_server.cpp

@@ -0,0 +1,91 @@
+#include "asio.hpp"
+#include <string>
+#include <iostream>
+
+using asio::ip::tcp;
+
+class session
+  : public std::enable_shared_from_this<session>
+{
+public:
+  session(tcp::socket socket)
+    : socket_(std::move(socket))
+  {
+  }
+
+  void start()
+  {
+    do_read();
+  }
+
+private:
+  void do_read()
+  {
+    auto self(shared_from_this());
+    socket_.async_read_some(asio::buffer(data_, max_length),
+        [this, self](std::error_code ec, std::size_t length)
+        {
+          if (!ec)
+          {
+            std::cout << data_ << std::endl;
+            do_write(length);
+          }
+        });
+  }
+
+  void do_write(std::size_t length)
+  {
+    auto self(shared_from_this());
+    asio::async_write(socket_, asio::buffer(data_, length),
+        [this, self](std::error_code ec, std::size_t length)
+        {
+          if (!ec)
+          {
+            do_read();
+          }
+        });
+  }
+
+  tcp::socket socket_;
+  enum { max_length = 1024 };
+  char data_[max_length];
+};
+
+class server
+{
+public:
+  server(asio::io_context& io_context, short port)
+    : acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
+  {
+    do_accept();
+  }
+
+private:
+  void do_accept()
+  {
+    acceptor_.async_accept(
+        [this](std::error_code ec, tcp::socket socket)
+        {
+          if (!ec)
+          {
+            std::make_shared<session>(std::move(socket))->start();
+          }
+
+          do_accept();
+        });
+  }
+
+  tcp::acceptor acceptor_;
+};
+
+
+void asio_main()
+{
+
+    asio::io_context io_context;
+
+    server s(io_context, std::atoi(CONFIG_EXAMPLE_PORT));
+
+    io_context.run();
+
+}

examples/protocols/asio/tcp_echo_server/sdkconfig.defaults

@@ -0,0 +1 @@
+CONFIG_MAIN_TASK_STACK_SIZE=8192

examples/protocols/asio/udp_echo_server/Makefile

@@ -0,0 +1,7 @@
+#
+# This is a project Makefile. It is assumed the directory this Makefile resides in is a
+# project subdirectory.
+#
+PROJECT_NAME := asio_udp_echoserver
+
+include $(IDF_PATH)/make/project.mk

examples/protocols/asio/udp_echo_server/README.md

@@ -0,0 +1,18 @@
+# ASIO udp echo server example
+
+Simple asio echo server using WiFi STA
+
+## Example workflow
+
+- WiFi STA is started and trying to connect to the access point defined through `make menuconfig`
+- Once connected and acquired IP address, ASIO udp server is started on port number defined through `make menuconfig`
+- Server receives and echoes back messages transmitted from client
+
+## Running the example
+
+- Run `make menuconfig` to configure the access point's SSID and Password and port number
+- Run `make flash monitor` to build and upload the example to your board and connect to it's serial terminal
+- Wait for WiFi to connect to your access point (note the IP address)
+- You can now send a udp message and check it is repeated, for example using netcat `nc -u IP PORT`
+
+See the README.md file in the upper level 'examples' directory for more information about examples.

examples/protocols/asio/udp_echo_server/asio_udp_server_test.py

@@ -0,0 +1,58 @@
+import re
+import os
+import sys
+from socket import *
+
+
+# this is a test case write with tiny-test-fw.
+# to run test cases outside tiny-test-fw,
+# we need to set environment variable `TEST_FW_PATH`,
+# then get and insert `TEST_FW_PATH` to sys path before import FW module
+test_fw_path = os.getenv("TEST_FW_PATH")
+if test_fw_path and test_fw_path not in sys.path:
+    sys.path.insert(0, test_fw_path)
+
+import TinyFW
+import IDF
+
+
+
+
+@IDF.idf_example_test(env_tag="Example_WIFI")
+def test_examples_protocol_asio_udp_server(env, extra_data):
+    """
+    steps: |
+      1. join AP
+      2. Start server
+      3. Test connects to server and sends a test message
+      4. Test evaluates received test message from server
+      5. Test evaluates received test message on server stdout
+    """
+    test_msg="echo message from client to server"
+    dut1 = env.get_dut("udp_echo_server", "examples/protocols/asio/udp_echo_server")
+    # check and log bin size
+    binary_file = os.path.join(dut1.app.binary_path, "asio_udp_echoserver.bin")
+    bin_size = os.path.getsize(binary_file)
+    IDF.log_performance("asio_udp_echoserver_bin_size", "{}KB".format(bin_size//1024))
+    IDF.check_performance("asio_udp_echoserver_size", bin_size//1024)
+    # 1. start test
+    dut1.start_app()
+    # 2. get the server IP address
+    data = dut1.expect(re.compile(r" sta ip: ([^,]+),"))
+    # 3. create tcp client and connect to server
+    cli = socket(AF_INET, SOCK_DGRAM)
+    cli.connect((data[0], 80))
+    cli.send(test_msg)
+    data = cli.recv(1024)
+    # 4. check the message received back from the server
+    if (data == test_msg):
+        print("PASS: Received correct message")
+        pass
+    else:
+        print("Failure!")
+        raise ValueError('Wrong data received from asi udp server: {} (expoected:{})'.format(data, test_msg))
+    # 5. check the client message appears also on server terminal
+    dut1.expect(test_msg)
+
+if __name__ == '__main__':
+    test_examples_protocol_asio_udp_server()

examples/protocols/asio/udp_echo_server/components/component.mk

@@ -0,0 +1,10 @@
+#
+# Component Makefile
+#
+# This Makefile should, at the very least, just include $(SDK_PATH)/Makefile. By default, 
+# this will take the sources in the src/ directory, compile them and link them into 
+# lib(subdirectory_name).a in the build directory. This behaviour is entirely configurable,
+# please read the SDK documents if you need to do this.
+#
+
+COMPONENT_SRCDIRS = .

examples/protocols/asio/udp_echo_server/components/wifi_asio.cpp

@@ -0,0 +1,136 @@
+/* Common WiFi Init as STA for ASIO examples
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/event_groups.h"
+#include "esp_system.h"
+#include "esp_wifi.h"
+#include "esp_event_loop.h"
+#include "esp_log.h"
+#include "nvs_flash.h"
+#include "driver/uart.h"
+#include "esp_console.h"
+#include "esp_vfs_dev.h"
+
+#include "lwip/err.h"
+#include "lwip/sys.h"
+
+#include <cstring>
+
+/* The examples use simple WiFi configuration that you can set via
+   'make menuconfig'.
+
+   If you'd rather not, just change the below entries to strings with
+   the config you want - ie #define EXAMPLE_WIFI_SSID "mywifissid"
+*/
+#define EXAMPLE_ESP_WIFI_SSID      CONFIG_ESP_WIFI_SSID
+#define EXAMPLE_ESP_WIFI_PASS      CONFIG_ESP_WIFI_PASSWORD
+
+/* FreeRTOS event group to signal when we are connected*/
+static EventGroupHandle_t wifi_event_group;
+
+/* The event group allows multiple bits for each event,
+   but we only care about one event - are we connected
+   to the AP with an IP? */
+const int WIFI_CONNECTED_BIT = BIT0;
+
+static const char *TAG = "asio example wifi init";
+
+/**
+ *  Definition of ASIO main method, which is called after network initialized
+ */
+void asio_main();
+
+static esp_err_t event_handler(void *ctx, system_event_t *event)
+{
+    switch(event->event_id) {
+    case SYSTEM_EVENT_STA_START:
+        esp_wifi_connect();
+        break;
+    case SYSTEM_EVENT_STA_GOT_IP:
+        ESP_LOGI(TAG, "got ip:%s",
+                 ip4addr_ntoa(&event->event_info.got_ip.ip_info.ip));
+        xEventGroupSetBits(wifi_event_group, WIFI_CONNECTED_BIT);
+        break;
+    case SYSTEM_EVENT_AP_STACONNECTED:
+        ESP_LOGI(TAG, "station:" MACSTR " join, AID=%d",
+                 MAC2STR(event->event_info.sta_connected.mac),
+                 event->event_info.sta_connected.aid);
+        break;
+    case SYSTEM_EVENT_AP_STADISCONNECTED:
+        ESP_LOGI(TAG, "station:" MACSTR "leave, AID=%d",
+                 MAC2STR(event->event_info.sta_disconnected.mac),
+                 event->event_info.sta_disconnected.aid);
+        break;
+    case SYSTEM_EVENT_STA_DISCONNECTED:
+        esp_wifi_connect();
+        xEventGroupClearBits(wifi_event_group, WIFI_CONNECTED_BIT);
+        break;
+    default:
+        break;
+    }
+    return ESP_OK;
+}
+
+void wifi_init_sta()
+{
+    wifi_event_group = xEventGroupCreate();
+
+    tcpip_adapter_init();
+    ESP_ERROR_CHECK(esp_event_loop_init(event_handler, NULL) );
+
+    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
+    ESP_ERROR_CHECK(esp_wifi_init(&cfg));
+    wifi_config_t wifi_config;
+    // zero out the config struct to ensure defaults are setup
+    memset(&wifi_config, 0, sizeof(wifi_sta_config_t));
+    // only copy ssid&password from example config
+    strcpy((char*)(wifi_config.sta.ssid), EXAMPLE_ESP_WIFI_SSID);
+    strcpy((char*)(wifi_config.sta.password), EXAMPLE_ESP_WIFI_PASS);
+
+    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA) );
+    ESP_ERROR_CHECK(esp_wifi_set_config(ESP_IF_WIFI_STA, &wifi_config) );
+    ESP_ERROR_CHECK(esp_wifi_start() );
+
+    ESP_LOGI(TAG, "wifi_init_sta finished.");
+    ESP_LOGI(TAG, "connect to ap SSID:%s password:%s",
+             EXAMPLE_ESP_WIFI_SSID, EXAMPLE_ESP_WIFI_PASS);
+}
+
+extern "C" void app_main()
+{
+    //Initialize NVS
+    esp_err_t ret = nvs_flash_init();
+    if (ret == ESP_ERR_NVS_NO_FREE_PAGES) {
+      ESP_ERROR_CHECK(nvs_flash_erase());
+      ret = nvs_flash_init();
+    }
+    ESP_ERROR_CHECK(ret);
+    
+    ESP_LOGI(TAG, "ESP_WIFI_MODE_AP");
+    wifi_init_sta();
+
+    // Initialize VFS & UART so we can use std::cout/cin
+    setvbuf(stdin, NULL, _IONBF, 0);
+    setvbuf(stdout, NULL, _IONBF, 0);
+    /* Install UART driver for interrupt-driven reads and writes */
+    ESP_ERROR_CHECK( uart_driver_install( (uart_port_t)CONFIG_CONSOLE_UART_NUM,
+            256, 0, 0, NULL, 0) );
+    /* Tell VFS to use UART driver */
+    esp_vfs_dev_uart_use_driver(CONFIG_CONSOLE_UART_NUM);
+    esp_vfs_dev_uart_set_rx_line_endings(ESP_LINE_ENDINGS_CR);
+    /* Move the caret to the beginning of the next line on '\n' */
+    esp_vfs_dev_uart_set_tx_line_endings(ESP_LINE_ENDINGS_CRLF);
+
+    // wait till we receive IP, so asio realated code can be started
+    xEventGroupWaitBits(wifi_event_group, WIFI_CONNECTED_BIT, 1, 1, portMAX_DELAY);
+
+    // network is ready, let's proceed with ASIO example
+    asio_main();
+}

examples/protocols/asio/udp_echo_server/main/Kconfig.projbuild

@@ -0,0 +1,21 @@
+menu "Example Configuration"
+
+config ESP_WIFI_SSID
+    string "WiFi SSID"
+    default "myssid"
+    help
+	SSID (network name) for the example to connect to.
+
+config ESP_WIFI_PASSWORD
+    string "WiFi Password"
+    default "mypassword"
+    help
+	WiFi password (WPA or WPA2) for the example to use.
+
+config EXAMPLE_PORT
+    string "asio example port number"
+    default "80"
+    help
+    Port number used by ASIO example
+
+endmenu

examples/protocols/asio/udp_echo_server/main/component.mk

@@ -0,0 +1,8 @@
+#
+# Main component makefile.
+#
+# This Makefile can be left empty. By default, it will take the sources in the 
+# src/ directory, compile them and link them into lib(subdirectory_name).a 
+# in the build directory. This behaviour is entirely configurable,
+# please read the ESP-IDF documents if you need to do this.
+#

examples/protocols/asio/udp_echo_server/main/udp_echo_server.cpp

@@ -0,0 +1,69 @@
+//
+// async_udp_echo_server.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstdlib>
+#include <iostream>
+
+#include "asio.hpp"
+
+using asio::ip::udp;
+
+class server
+{
+public:
+  server(asio::io_context& io_context, short port)
+    : socket_(io_context, udp::endpoint(udp::v4(), port))
+  {
+    do_receive();
+  }
+
+  void do_receive()
+  {
+    socket_.async_receive_from(
+        asio::buffer(data_, max_length), sender_endpoint_,
+        [this](std::error_code ec, std::size_t bytes_recvd)
+        {
+          if (!ec && bytes_recvd > 0)
+          {
+            std::cout << data_ << std::endl;
+            do_send(bytes_recvd);
+          }
+          else
+          {
+            do_receive();
+          }
+        });
+  }
+
+  void do_send(std::size_t length)
+  {
+    socket_.async_send_to(
+        asio::buffer(data_, length), sender_endpoint_,
+        [this](std::error_code /*ec*/, std::size_t  bytes /*bytes_sent*/)
+        {
+          do_receive();
+        });
+  }
+
+private:
+  udp::socket socket_;
+  udp::endpoint sender_endpoint_;
+  enum { max_length = 1024 };
+  char data_[max_length];
+};
+
+void asio_main()
+{
+    asio::io_context io_context;
+
+    server s(io_context, std::atoi(CONFIG_EXAMPLE_PORT));
+
+    io_context.run();
+}

examples/protocols/asio/udp_echo_server/sdkconfig.defaults

@@ -0,0 +1 @@
+CONFIG_MAIN_TASK_STACK_SIZE=8192

examples/protocols/asio/wifi_init/wifi_asio.cpp

@@ -0,0 +1,136 @@
+/* Common WiFi Init as STA for ASIO examples
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/event_groups.h"
+#include "esp_system.h"
+#include "esp_wifi.h"
+#include "esp_event_loop.h"
+#include "esp_log.h"
+#include "nvs_flash.h"
+#include "driver/uart.h"
+#include "esp_console.h"
+#include "esp_vfs_dev.h"
+
+#include "lwip/err.h"
+#include "lwip/sys.h"
+
+#include <cstring>
+
+/* The examples use simple WiFi configuration that you can set via
+   'make menuconfig'.
+
+   If you'd rather not, just change the below entries to strings with
+   the config you want - ie #define EXAMPLE_WIFI_SSID "mywifissid"
+*/
+#define EXAMPLE_ESP_WIFI_SSID      CONFIG_ESP_WIFI_SSID
+#define EXAMPLE_ESP_WIFI_PASS      CONFIG_ESP_WIFI_PASSWORD
+
+/* FreeRTOS event group to signal when we are connected*/
+static EventGroupHandle_t wifi_event_group;
+
+/* The event group allows multiple bits for each event,
+   but we only care about one event - are we connected
+   to the AP with an IP? */
+const int WIFI_CONNECTED_BIT = BIT0;
+
+static const char *TAG = "asio example wifi init";
+
+/**
+ *  Definition of ASIO main method, which is called after network initialized
+ */
+void asio_main();
+
+static esp_err_t event_handler(void *ctx, system_event_t *event)
+{
+    switch(event->event_id) {
+    case SYSTEM_EVENT_STA_START:
+        esp_wifi_connect();
+        break;
+    case SYSTEM_EVENT_STA_GOT_IP:
+        ESP_LOGI(TAG, "got ip:%s",
+                 ip4addr_ntoa(&event->event_info.got_ip.ip_info.ip));
+        xEventGroupSetBits(wifi_event_group, WIFI_CONNECTED_BIT);
+        break;
+    case SYSTEM_EVENT_AP_STACONNECTED:
+        ESP_LOGI(TAG, "station:" MACSTR " join, AID=%d",
+                 MAC2STR(event->event_info.sta_connected.mac),
+                 event->event_info.sta_connected.aid);
+        break;
+    case SYSTEM_EVENT_AP_STADISCONNECTED:
+        ESP_LOGI(TAG, "station:" MACSTR "leave, AID=%d",
+                 MAC2STR(event->event_info.sta_disconnected.mac),
+                 event->event_info.sta_disconnected.aid);
+        break;
+    case SYSTEM_EVENT_STA_DISCONNECTED:
+        esp_wifi_connect();
+        xEventGroupClearBits(wifi_event_group, WIFI_CONNECTED_BIT);
+        break;
+    default:
+        break;
+    }
+    return ESP_OK;
+}
+
+void wifi_init_sta()
+{
+    wifi_event_group = xEventGroupCreate();
+
+    tcpip_adapter_init();
+    ESP_ERROR_CHECK(esp_event_loop_init(event_handler, NULL) );
+
+    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
+    ESP_ERROR_CHECK(esp_wifi_init(&cfg));
+    wifi_config_t wifi_config;
+    // zero out the config struct to ensure defaults are setup
+    memset(&wifi_config, 0, sizeof(wifi_sta_config_t));
+    // only copy ssid&password from example config
+    strcpy((char*)(wifi_config.sta.ssid), EXAMPLE_ESP_WIFI_SSID);
+    strcpy((char*)(wifi_config.sta.password), EXAMPLE_ESP_WIFI_PASS);
+
+    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA) );
+    ESP_ERROR_CHECK(esp_wifi_set_config(ESP_IF_WIFI_STA, &wifi_config) );
+    ESP_ERROR_CHECK(esp_wifi_start() );
+
+    ESP_LOGI(TAG, "wifi_init_sta finished.");
+    ESP_LOGI(TAG, "connect to ap SSID:%s password:%s",
+             EXAMPLE_ESP_WIFI_SSID, EXAMPLE_ESP_WIFI_PASS);
+}
+
+extern "C" void app_main()
+{
+    //Initialize NVS
+    esp_err_t ret = nvs_flash_init();
+    if (ret == ESP_ERR_NVS_NO_FREE_PAGES) {
+      ESP_ERROR_CHECK(nvs_flash_erase());
+      ret = nvs_flash_init();
+    }
+    ESP_ERROR_CHECK(ret);
+    
+    ESP_LOGI(TAG, "ESP_WIFI_MODE_AP");
+    wifi_init_sta();
+
+    // Initialize VFS & UART so we can use std::cout/cin
+    setvbuf(stdin, NULL, _IONBF, 0);
+    setvbuf(stdout, NULL, _IONBF, 0);
+    /* Install UART driver for interrupt-driven reads and writes */
+    ESP_ERROR_CHECK( uart_driver_install( (uart_port_t)CONFIG_CONSOLE_UART_NUM,
+            256, 0, 0, NULL, 0) );
+    /* Tell VFS to use UART driver */
+    esp_vfs_dev_uart_use_driver(CONFIG_CONSOLE_UART_NUM);
+    esp_vfs_dev_uart_set_rx_line_endings(ESP_LINE_ENDINGS_CR);
+    /* Move the caret to the beginning of the next line on '\n' */
+    esp_vfs_dev_uart_set_tx_line_endings(ESP_LINE_ENDINGS_CRLF);
+
+    // wait till we receive IP, so asio realated code can be started
+    xEventGroupWaitBits(wifi_event_group, WIFI_CONNECTED_BIT, 1, 1, portMAX_DELAY);
+
+    // network is ready, let's proceed with ASIO example
+    asio_main();
+}