esp-idf/examples/protocols/sockets/tcp_client/main/tcp_client_v4.c

/*
 * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Unlicense OR CC0-1.0
 */
#include "sdkconfig.h"
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <errno.h>
#include <netdb.h>            // struct addrinfo
#include <arpa/inet.h>
#include "esp_netif.h"
#include "esp_log.h"
#if defined(CONFIG_EXAMPLE_SOCKET_IP_INPUT_STDIN)
#include "addr_from_stdin.h"
#endif

#if defined(CONFIG_EXAMPLE_IPV4)
#define HOST_IP_ADDR CONFIG_EXAMPLE_IPV4_ADDR
#elif defined(CONFIG_EXAMPLE_SOCKET_IP_INPUT_STDIN)
#define HOST_IP_ADDR ""
#endif

#define PORT CONFIG_EXAMPLE_PORT

static const char *TAG = "example";
static const char *payload = "Message from ESP32 ";


void tcp_client(void)
{
    char rx_buffer[128];
    char host_ip[] = HOST_IP_ADDR;
    int addr_family = 0;
    int ip_protocol = 0;

    while (1) {
#if defined(CONFIG_EXAMPLE_IPV4)
        struct sockaddr_in dest_addr;
        inet_pton(AF_INET, host_ip, &dest_addr.sin_addr);
        dest_addr.sin_family = AF_INET;
        dest_addr.sin_port = htons(PORT);
        addr_family = AF_INET;
        ip_protocol = IPPROTO_IP;
#elif defined(CONFIG_EXAMPLE_SOCKET_IP_INPUT_STDIN)
        struct sockaddr_storage dest_addr = { 0 };
        ESP_ERROR_CHECK(get_addr_from_stdin(PORT, SOCK_STREAM, &ip_protocol, &addr_family, &dest_addr));
#endif

        int sock =  socket(addr_family, SOCK_STREAM, ip_protocol);
        if (sock < 0) {
            ESP_LOGE(TAG, "Unable to create socket: errno %d", errno);
            break;
        }
        ESP_LOGI(TAG, "Socket created, connecting to %s:%d", host_ip, PORT);

        int err = connect(sock, (struct sockaddr *)&dest_addr, sizeof(dest_addr));
        if (err != 0) {
            ESP_LOGE(TAG, "Socket unable to connect: errno %d", errno);
            break;
        }
        ESP_LOGI(TAG, "Successfully connected");

        while (1) {
            int err = send(sock, payload, strlen(payload), 0);
            if (err < 0) {
                ESP_LOGE(TAG, "Error occurred during sending: errno %d", errno);
                break;
            }

            int len = recv(sock, rx_buffer, sizeof(rx_buffer) - 1, 0);
            // Error occurred during receiving
            if (len < 0) {
                ESP_LOGE(TAG, "recv failed: errno %d", errno);
                break;
            }
            // Data received
            else {
                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);
            }
        }

        if (sock != -1) {
            ESP_LOGE(TAG, "Shutting down socket and restarting...");
            shutdown(sock, 0);
            close(sock);
        }
    }
}