examples: Added non blocking sockets example tests

Closes https://github.com/espressif/esp-idf/issues/6675

examples/protocols/sockets_non_blocking/tcp_server/CMakeLists.txt

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+# The following five lines of boilerplate have to be in your project's
+# CMakeLists in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.5)
+
+# (Not part of the boilerplate)
+# This example uses an extra component for common functions such as Wi-Fi and Ethernet connection.
+set(EXTRA_COMPONENT_DIRS $ENV{IDF_PATH}/examples/common_components/protocol_examples_common)
+set(EXCLUDE_COMPONENTS "coap" "asio")
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(tcp_server)

examples/protocols/sockets_non_blocking/tcp_server/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 := tcp_server
+
+EXTRA_COMPONENT_DIRS = $(IDF_PATH)/examples/common_components/protocol_examples_common
+EXCLUDE_COMPONENTS = coap asio
+
+include $(IDF_PATH)/make/project.mk

examples/protocols/sockets_non_blocking/tcp_server/README.md

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+
+# TCP Server example
+
+(See the README.md file in the upper level 'examples' directory for more information about examples.)
+
+The application creates a non-blocking TCP socket with the specified port number and polls till a connection request from the client arrives. After accepting a request from the client, a connection between server and client is established and the application polls for some data to be received from the client. Received data are printed as ASCII text and retransmitted back to the client.
+
+## How to use example
+
+In order to create TCP client that communicates with TCP server example, choose one of the following options.
+
+There are many host-side tools which can be used to interact with the UDP/TCP server/client. 
+One command line tool is [netcat](http://netcat.sourceforge.net) which can send and receive many kinds of packets. 
+Note: please replace `192.168.0.167 3333` with desired IPV4/IPV6 address (displayed in monitor console) and port number in the following command.
+
+In addition to those tools, simple Python scripts can be found under sockets/scripts directory. Every script is designed to interact with one of the examples.
+
+### TCP client using netcat
+```
+nc 192.168.0.167 3333
+```
+
+### Python scripts
+Script example_test.py could be used as a counter part to the tcp-server application,
+IP address and the message to be send to the server shall be stated as arguments. Example:
+
+```
+python example_test.py 192.168.0.167 Message
+```
+Note that this script is used in automated tests, as well, so the IDF test framework packages need to be imported;
+please add `$IDF_PATH/tools/ci/python_packages` to `PYTHONPATH`.
+
+## Hardware Required
+
+This example can be run on any commonly available ESP32 development board.
+
+## Configure the project
+
+```
+idf.py menuconfig
+```
+
+Set following parameters under Example Configuration Options:
+
+* Set `IP version` of the example to be IPV4 or IPV6.
+
+* Set `Port` number of the socket, that server example will create.
+
+* Set `TCP keep-alive idle time(s)` value of TCP keep alive idle time. This time is the time between the last data transmission.
+
+* Set `TCP keep-alive interval time(s)` value of TCP keep alive interval time. This time is the interval time of keepalive probe packets.
+
+* Set `TCP keep-alive packet retry send counts` value of TCP keep alive packet retry send counts. This is the number of retries of the keepalive probe packet.
+
+Configure Wi-Fi or Ethernet under "Example Connection Configuration" menu. See "Establishing Wi-Fi or Ethernet Connection" section in [examples/protocols/README.md](../../README.md) for more details.
+
+## Build and Flash
+
+Build the project and flash it to the board, then run monitor tool to view serial output:
+
+```
+idf.py -p PORT flash monitor
+```
+
+(To exit the serial monitor, type ``Ctrl-]``.)
+
+See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
+
+
+## Troubleshooting
+
+Start server first, to receive data sent from the client (application).

examples/protocols/sockets_non_blocking/tcp_server/example_test.py

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+# 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.
+
+# -*- coding: utf-8 -*-
+
+from __future__ import print_function, unicode_literals
+
+import os
+import re
+import socket
+import sys
+
+import ttfw_idf
+
+# -----------  Config  ----------
+PORT = 3344
+INTERFACE = 'eth0'
+# -------------------------------
+
+
+def tcp_client(address, payload):
+    for res in socket.getaddrinfo(address, PORT, socket.AF_UNSPEC,
+                                  socket.SOCK_STREAM, 0, socket.AI_PASSIVE):
+        family_addr, socktype, proto, canonname, addr = res
+    try:
+        sock = socket.socket(family_addr, socket.SOCK_STREAM)
+        sock.settimeout(60.0)
+    except socket.error as msg:
+        print('Could not create socket: ' + msg)
+        raise
+    try:
+        sock.connect(addr)
+    except socket.error as msg:
+        print('Could not open socket: ', msg)
+        sock.close()
+        raise
+    sock.sendall(payload.encode())
+    data = sock.recv(1024)
+    if not data:
+        return ''
+    print('Reply : ' + data.decode())
+    sock.close()
+    return data.decode()
+
+
+@ttfw_idf.idf_example_test(env_tag='Example_WIFI')
+def test_examples_protocol_socket_tcpserver(env, extra_data):
+    """
+    steps:
+      1. join AP
+      2. have the board connect to the server
+      3. send and receive data
+    """
+    msg = 'Data to ESP'
+    dut1 = env.get_dut('tcp_client', 'examples/protocols/sockets_non_blocking/tcp_server', dut_class=ttfw_idf.ESP32DUT)
+    # check and log bin size
+    binary_file = os.path.join(dut1.app.binary_path, 'tcp_server.bin')
+    bin_size = os.path.getsize(binary_file)
+    ttfw_idf.log_performance('tcp_server_bin_size', '{}KB'.format(bin_size // 1024))
+
+    # start test
+    dut1.start_app()
+    ipv4 = dut1.expect(re.compile(r' IPv4 address: ([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+)'), timeout=30)[0]
+    ipv6_r = r':'.join((r'[0-9a-fA-F]{4}',) * 8)    # expect all 8 octets from IPv6 (assumes it's printed in the long form)
+    ipv6 = dut1.expect(re.compile(r' IPv6 address: ({})'.format(ipv6_r)), timeout=30)[0]
+    print('Connected with IPv4={} and IPv6={}'.format(ipv4, ipv6))
+
+    # test IPv4
+    received = tcp_client(ipv4, msg)
+    if received != msg:
+        raise
+    dut1.expect(msg)
+
+    # test IPv6
+    received = tcp_client('{}%{}'.format(ipv6, INTERFACE), msg)
+    if received != msg:
+        raise
+    dut1.expect(msg)
+
+
+if __name__ == '__main__':
+    if sys.argv[2:]:    # if two arguments provided:
+        # Usage: example_test.py <server_address> <message_to_send_to_server>
+        tcp_client(sys.argv[1], sys.argv[2])
+    else:               # otherwise run standard example test as in the CI
+        test_examples_protocol_socket_tcpserver()

examples/protocols/sockets_non_blocking/tcp_server/main/CMakeLists.txt

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+idf_component_register(SRCS "tcp_server.c"
+                    INCLUDE_DIRS ".")

examples/protocols/sockets_non_blocking/tcp_server/main/Kconfig.projbuild

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+menu "Example Configuration"
+
+    config EXAMPLE_IPV4
+        bool "IPV4"
+        default y
+
+    config EXAMPLE_IPV6
+        bool "IPV6"
+        default n
+        select EXAMPLE_CONNECT_IPV6
+
+    config EXAMPLE_PORT
+        int "Port"
+        range 0 65535
+        default 3344
+        help
+            Local port the example server will listen on.
+
+    config EXAMPLE_KEEPALIVE_IDLE
+        int "TCP keep-alive idle time(s)"
+        default 5
+        help
+            Keep-alive idle time. In idle time without receiving any data from peer, will send keep-alive probe packet
+
+    config EXAMPLE_KEEPALIVE_INTERVAL
+        int "TCP keep-alive interval time(s)"
+        default 5
+        help
+            Keep-alive probe packet interval time.
+
+    config EXAMPLE_KEEPALIVE_COUNT
+        int "TCP keep-alive packet retry send counts"
+        default 3
+        help
+            Keep-alive probe packet retry count.
+endmenu

examples/protocols/sockets_non_blocking/tcp_server/main/component.mk

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+#
+# "main" pseudo-component makefile.
+#
+# (Uses default behaviour of compiling all source files in directory, adding 'include' to include path.)

examples/protocols/sockets_non_blocking/tcp_server/main/tcp_server.c

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+/* BSD Socket API Example
+
+   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 <string.h>
+#include <sys/param.h>
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "esp_system.h"
+#include "esp_wifi.h"
+#include "esp_event.h"
+#include "esp_log.h"
+#include "nvs_flash.h"
+#include "esp_netif.h"
+#include "protocol_examples_common.h"
+
+#include "lwip/err.h"
+#include "lwip/sockets.h"
+#include "lwip/sys.h"
+#include <lwip/netdb.h>
+#include <errno.h>
+
+
+#define PORT                        CONFIG_EXAMPLE_PORT
+#define KEEPALIVE_IDLE              CONFIG_EXAMPLE_KEEPALIVE_IDLE
+#define KEEPALIVE_INTERVAL          CONFIG_EXAMPLE_KEEPALIVE_INTERVAL
+#define KEEPALIVE_COUNT             CONFIG_EXAMPLE_KEEPALIVE_COUNT
+
+static const char *TAG = "example";
+
+static void do_retransmit(const int sock)
+{
+    int len;
+    char rx_buffer[128];
+
+    do {
+        ESP_LOGI(TAG, "Waiting for receiving data");
+        len = recv(sock, rx_buffer, sizeof(rx_buffer) - 1, 0);
+        if (len < 0) {
+            ESP_LOGE(TAG, "Error occurred during receiving: errno %d", errno);
+        } else if (len == 0) {
+            ESP_LOGW(TAG, "Connection closed");
+        } else {
+            rx_buffer[len] = 0; // Null-terminate whatever is received and treat it like a string
+            ESP_LOGI(TAG, "Received %d bytes: %s", len, rx_buffer);
+
+            // send() can return less bytes than supplied length.
+            // Walk-around for robust implementation.
+            int to_write = len;
+            while (to_write > 0) {
+                int written = send(sock, rx_buffer + (len - to_write), to_write, 0);
+                if (written < 0) {
+                    ESP_LOGE(TAG, "Error occurred during sending: errno %d", errno);
+					break;
+                }
+                to_write -= written;
+            }
+        }
+    } while (len > 0);
+}
+
+static void tcp_server_task(void *pvParameters)
+{
+    char addr_str[128];
+    int addr_family = (int)pvParameters;
+    int ip_protocol = 0;
+    struct sockaddr_storage dest_addr;
+
+    if (addr_family == AF_INET) {
+        struct sockaddr_in *dest_addr_ip4 = (struct sockaddr_in *)&dest_addr;
+        dest_addr_ip4->sin_addr.s_addr = htonl(INADDR_ANY);
+        dest_addr_ip4->sin_family = AF_INET;
+        dest_addr_ip4->sin_port = htons(PORT);
+        ip_protocol = IPPROTO_IP;
+    }
+#ifdef CONFIG_EXAMPLE_IPV6
+    else if (addr_family == AF_INET6) {
+        struct sockaddr_in6 *dest_addr_ip6 = (struct sockaddr_in6 *)&dest_addr;
+        bzero(&dest_addr_ip6->sin6_addr.un, sizeof(dest_addr_ip6->sin6_addr.un));
+        dest_addr_ip6->sin6_family = AF_INET6;
+        dest_addr_ip6->sin6_port = htons(PORT);
+        ip_protocol = IPPROTO_IPV6;
+    }
+#endif
+
+    // Creating a listener socket
+    int listen_sock = socket(addr_family, SOCK_STREAM, ip_protocol);
+
+    if (listen_sock < 0) {
+        ESP_LOGE(TAG, "Unable to create socket: errno %d", errno);
+        vTaskDelete(NULL);
+        return;
+    }
+    ESP_LOGI(TAG, "Listenet socket created");
+
+    // Geting socket file descriptor flags
+    int flags = fcntl(listen_sock, F_GETFL);
+
+    // Marking the socket as non-blocking
+    if (fcntl(listen_sock, F_SETFL, flags | O_NONBLOCK) == -1) {
+        ESP_LOGE(TAG, "Unable to set socket non blocking: errno %d", errno);
+    }
+    ESP_LOGI(TAG, "Socket marked as non blocking");
+
+    // Binding socket to the given interface
+    int err = bind(listen_sock, (struct sockaddr *)&dest_addr, sizeof(dest_addr));
+
+    if (err != 0) {
+        ESP_LOGE(TAG, "Socket unable to bind: errno %d", errno);
+        ESP_LOGE(TAG, "IPPROTO: %d", addr_family);
+        goto CLEAN_UP;
+    }
+    ESP_LOGI(TAG, "Socket bound on port %d", PORT);
+
+    // Set queue of pending connections to one(can be more)
+    err = listen(listen_sock, 1);
+
+    if (err != 0) {
+        ESP_LOGE(TAG, "Error occurred during listen: errno %d", errno);
+        goto CLEAN_UP;
+    }
+
+    while (1) {
+        ESP_LOGI(TAG, "Socket listening");
+        struct sockaddr_storage source_addr; // Large enough for both IPv4 or IPv6
+        socklen_t addr_len = sizeof(source_addr);
+
+        // Start listening for incoming connections in non-blocking mode
+        int sock = accept(listen_sock, (struct sockaddr *)&source_addr, &addr_len);
+
+        if (sock < 0) {
+            if (errno == EWOULDBLOCK) { // This is what we expect(Continue looping)
+                ESP_LOGD(TAG, "No pending connections; sleeping for one second.\n");
+                continue;
+            } else {
+                ESP_LOGE(TAG, "Error when accepting connection: error %s", strerror(errno));
+                break;
+            }
+        }
+
+        // Convert ip address to string
+        if (source_addr.ss_family == PF_INET) {
+            inet_ntoa_r(((struct sockaddr_in *)&source_addr)->sin_addr, addr_str, sizeof(addr_str) - 1);
+        }
+#ifdef CONFIG_EXAMPLE_IPV6
+        else if (source_addr.ss_family == PF_INET6) {
+            inet6_ntoa_r(((struct sockaddr_in6 *)&source_addr)->sin6_addr, addr_str, sizeof(addr_str) - 1);
+        }
+#endif
+        ESP_LOGI(TAG, "Socket accepted ip address: %s", addr_str);
+        do_retransmit(sock);
+    }
+
+CLEAN_UP:
+    close(listen_sock);
+    vTaskDelete(NULL);
+}
+
+void app_main(void)
+{
+    ESP_ERROR_CHECK(nvs_flash_init());
+    ESP_ERROR_CHECK(esp_netif_init());
+    ESP_ERROR_CHECK(esp_event_loop_create_default());
+
+    /* This helper function configures Wi-Fi or Ethernet, as selected in menuconfig.
+     * Read "Establishing Wi-Fi or Ethernet Connection" section in
+     * examples/protocols/README.md for more information about this function.
+     */
+    ESP_ERROR_CHECK(example_connect());
+
+#ifdef CONFIG_EXAMPLE_IPV4
+    xTaskCreate(tcp_server_task, "tcp_server", 4096, (void*)AF_INET, 5, NULL);
+#endif
+#ifdef CONFIG_EXAMPLE_IPV6
+    xTaskCreate(tcp_server_task, "tcp_server", 4096, (void*)AF_INET6, 5, NULL);
+#endif
+}

examples/protocols/sockets_non_blocking/tcp_server/sdkconfig.ci

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+CONFIG_EXAMPLE_IPV4=y
+CONFIG_EXAMPLE_IPV6=y

examples/protocols/sockets_non_blocking/tcp_server/sdkconfig.ci.1

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+CONFIG_EXAMPLE_IPV4=y
+CONFIG_EXAMPLE_IPV6=n
+CONFIG_EXAMPLE_CONNECT_IPV6=n
+CONFIG_LWIP_IPV6=n