Create TCP Client using TCP TRANSPORT instead of socket

Update error logs with returned values. Add transport_tcp_init() error check.Clean up

examples/protocols/sockets/tcp_transport_client/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 $ENV{IDF_PATH}/examples/common_components/protocol_examples_common)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(tcp_transport_client)

examples/protocols/sockets/tcp_transport_client/README.md

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+| Supported Targets | ESP32 | ESP32-C2 | ESP32-C3 | ESP32-S2 | ESP32-S3 |
+| ----------------- | ----- | -------- | -------- | -------- | -------- |
+
+
+# TCP TRANSPORT Client example
+
+(See the README.md file in the upper level 'examples' directory for more information about examples.)
+
+The application creates a TCP transport connection and tries to connect to the server with predefined IP address and port number. When a connection is successfully established, the application sends message and waits for the answer. After the server's reply, application prints received reply as ASCII text, waits for 2 seconds and sends another message.
+
+## How to use example
+
+In order to create TCP server that communicates with TCP TRANSPORT Client 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 server using netcat
+```
+nc -l 192.168.0.167 3333
+```
+
+## 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 `IPV4 Address` that represents remote host the example will connect to.
+
+* Set `Port` number that represents remote port the example will connect to.
+
+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/tcp_transport_client/main/CMakeLists.txt

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+idf_component_register(SRCS "tcp_transport_client.c"
+                       )

examples/protocols/sockets/tcp_transport_client/main/Kconfig.projbuild

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+menu "Example Configuration"
+
+    config EXAMPLE_IPV4_ADDR
+        string "IPV4 Address"
+        default "192.168.0.165"
+        help
+            The example will connect to this IPV4 address.
+
+    config EXAMPLE_PORT
+        int "Port"
+        range 0 65535
+        default 3333
+        help
+            The remote port to which the client example will connect to.
+
+endmenu

examples/protocols/sockets/tcp_transport_client/main/tcp_transport_client.c

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+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Unlicense OR CC0-1.0
+ */
+#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 "esp_transport.h"
+#include "esp_transport_tcp.h"
+
+
+#define HOST_IP_ADDR CONFIG_EXAMPLE_IPV4_ADDR
+
+#define PORT CONFIG_EXAMPLE_PORT
+
+static const char *TAG = "tcp_transport_client";
+static const char *payload = "Message from ESP32";
+
+static void tcp_transport_client_task(void *pvParameters)
+{
+    char rx_buffer[128];
+    char host_ip[] = HOST_IP_ADDR;
+    esp_transport_handle_t tcp = esp_transport_tcp_init();
+    while (1) {
+        if (tcp == NULL) {
+            ESP_LOGE(TAG, "Error occurred during esp_transport_tcp_init()");
+            break;
+        }
+        int err = esp_transport_connect(tcp, HOST_IP_ADDR, PORT, -1);
+        if (err != 0) {
+            ESP_LOGE(TAG, "Client unable to connect: errno %d", errno);
+            break;
+        }
+        ESP_LOGI(TAG, "Successfully connected");
+
+        while (1) {
+            int bytes_written = esp_transport_write(tcp, payload, strlen(payload), 0);
+            if (bytes_written < 0) {
+                ESP_LOGE(TAG, "Error occurred during sending: esp_transport_write() returned %d, errno %d", bytes_written, errno);
+                break;
+            }
+            int len = esp_transport_read(tcp, rx_buffer, sizeof(rx_buffer) - 1, 0);
+            // Error occurred during receiving
+            if (len < 0) {
+                ESP_LOGE(TAG, "recv failed: esp_transport_read() returned %d, errno %d", len, errno);
+                break;
+            }
+            // Data received
+                rx_buffer[len] = 0; // Null-terminate whatever we received and treat like a string
+                ESP_LOGI(TAG, "Received %d bytes from %s:", len, host_ip);
+                ESP_LOGI(TAG, "%s", rx_buffer);
+
+            vTaskDelay(2000 / portTICK_PERIOD_MS);
+        }
+
+            ESP_LOGE(TAG, "Shutting down TCP and restarting...");
+            esp_transport_close(tcp);
+    }
+    esp_transport_destroy(tcp);
+    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());
+
+    xTaskCreate(tcp_transport_client_task, "tcp_transport_client", 4096, NULL, 5, NULL);
+}