websocket_example.c

/*
 * SPDX-FileCopyrightText: 2022-2024 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Unlicense OR CC0-1.0
 */
/* ESP HTTP Client 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 <stdio.h>
#include "esp_wifi.h"
#include "esp_system.h"
#include "nvs_flash.h"
#include "esp_event.h"
#include "protocol_examples_common.h"

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/semphr.h"
#include "freertos/event_groups.h"

#include "esp_log.h"
#include "esp_websocket_client.h"
#include "esp_event.h"
#include <cJSON.h>

#define NO_DATA_TIMEOUT_SEC 5

static const char *TAG = "websocket";

static TimerHandle_t shutdown_signal_timer;
static SemaphoreHandle_t shutdown_sema;

static void log_error_if_nonzero(const char *message, int error_code)
{
    if (error_code != 0) {
        ESP_LOGE(TAG, "Last error %s: 0x%x", message, error_code);
    }
}

static void shutdown_signaler(TimerHandle_t xTimer)
{
    ESP_LOGI(TAG, "No data received for %d seconds, signaling shutdown", NO_DATA_TIMEOUT_SEC);
    xSemaphoreGive(shutdown_sema);
}

#if CONFIG_WEBSOCKET_URI_FROM_STDIN
static void get_string(char *line, size_t size)
{
    int count = 0;
    while (count < size) {
        int c = fgetc(stdin);
        if (c == '\n') {
            line[count] = '\0';
            break;
        } else if (c > 0 && c < 127) {
            line[count] = c;
            ++count;
        }
        vTaskDelay(10 / portTICK_PERIOD_MS);
    }
}

#endif /* CONFIG_WEBSOCKET_URI_FROM_STDIN */

static void websocket_event_handler(void *handler_args, esp_event_base_t base, int32_t event_id, void *event_data)
{
    esp_websocket_event_data_t *data = (esp_websocket_event_data_t *)event_data;
    switch (event_id) {
    case WEBSOCKET_EVENT_CONNECTED:
        ESP_LOGI(TAG, "WEBSOCKET_EVENT_CONNECTED");
        break;
    case WEBSOCKET_EVENT_DISCONNECTED:
        ESP_LOGI(TAG, "WEBSOCKET_EVENT_DISCONNECTED");
        log_error_if_nonzero("HTTP status code",  data->error_handle.esp_ws_handshake_status_code);
        if (data->error_handle.error_type == WEBSOCKET_ERROR_TYPE_TCP_TRANSPORT) {
            log_error_if_nonzero("reported from esp-tls", data->error_handle.esp_tls_last_esp_err);
            log_error_if_nonzero("reported from tls stack", data->error_handle.esp_tls_stack_err);
            log_error_if_nonzero("captured as transport's socket errno",  data->error_handle.esp_transport_sock_errno);
        }
        break;
    case WEBSOCKET_EVENT_DATA:
        ESP_LOGI(TAG, "WEBSOCKET_EVENT_DATA");
        ESP_LOGI(TAG, "Received opcode=%d", data->op_code);
        if (data->op_code == 0x08 && data->data_len == 2) {
            ESP_LOGW(TAG, "Received closed message with code=%d", 256 * data->data_ptr[0] + data->data_ptr[1]);
        } else {
            ESP_LOGW(TAG, "Received=%.*s", data->data_len, (char *)data->data_ptr);
        }

        // If received data contains json structure it succeed to parse
        cJSON *root = cJSON_Parse(data->data_ptr);
        if (root) {
            for (int i = 0 ; i < cJSON_GetArraySize(root) ; i++) {
                cJSON *elem = cJSON_GetArrayItem(root, i);
                cJSON *id = cJSON_GetObjectItem(elem, "id");
                cJSON *name = cJSON_GetObjectItem(elem, "name");
                ESP_LOGW(TAG, "Json={'id': '%s', 'name': '%s'}", id->valuestring, name->valuestring);
            }
            cJSON_Delete(root);
        }

        ESP_LOGW(TAG, "Total payload length=%d, data_len=%d, current payload offset=%d\r\n", data->payload_len, data->data_len, data->payload_offset);

        xTimerReset(shutdown_signal_timer, portMAX_DELAY);
        break;
    case WEBSOCKET_EVENT_ERROR:
        ESP_LOGI(TAG, "WEBSOCKET_EVENT_ERROR");
        log_error_if_nonzero("HTTP status code",  data->error_handle.esp_ws_handshake_status_code);
        if (data->error_handle.error_type == WEBSOCKET_ERROR_TYPE_TCP_TRANSPORT) {
            log_error_if_nonzero("reported from esp-tls", data->error_handle.esp_tls_last_esp_err);
            log_error_if_nonzero("reported from tls stack", data->error_handle.esp_tls_stack_err);
            log_error_if_nonzero("captured as transport's socket errno",  data->error_handle.esp_transport_sock_errno);
        }
        break;
    }
}

static void websocket_app_start(void)
{
    esp_websocket_client_config_t websocket_cfg = {};

    shutdown_signal_timer = xTimerCreate("Websocket shutdown timer", NO_DATA_TIMEOUT_SEC * 1000 / portTICK_PERIOD_MS,
                                         pdFALSE, NULL, shutdown_signaler);
    shutdown_sema = xSemaphoreCreateBinary();

#if CONFIG_WEBSOCKET_URI_FROM_STDIN
    char line[128];

    ESP_LOGI(TAG, "Please enter uri of websocket endpoint");
    get_string(line, sizeof(line));

    websocket_cfg.uri = line;
    ESP_LOGI(TAG, "Endpoint uri: %s\n", line);

#else
    websocket_cfg.uri = CONFIG_WEBSOCKET_URI;
#endif /* CONFIG_WEBSOCKET_URI_FROM_STDIN */

#if !CONFIG_ESP_TLS_SKIP_SERVER_CERT_VERIFY
    extern const char cacert_start[] asm("_binary_ca_cert_pem_start"); // CA certificate
    websocket_cfg.cert_pem = cacert_start;
#endif

    extern const char cert_start[] asm("_binary_client_cert_pem_start"); // Client certificate
    extern const char cert_end[]   asm("_binary_client_cert_pem_end");
    extern const char key_start[] asm("_binary_client_key_pem_start"); // Client private key
    extern const char key_end[]   asm("_binary_client_key_pem_end");

    // Please note if you don't use server over TLS scheme (wss), the certificates are not mandatory
    websocket_cfg.skip_cert_common_name_check = true;
    websocket_cfg.client_cert = cert_start;
    websocket_cfg.client_cert_len = cert_end - cert_start;
    websocket_cfg.client_key = key_start;
    websocket_cfg.client_key_len = key_end - key_start;

    ESP_LOGI(TAG, "Connecting to %s...", websocket_cfg.uri);

    esp_websocket_client_handle_t client = esp_websocket_client_init(&websocket_cfg);
    esp_websocket_register_events(client, WEBSOCKET_EVENT_ANY, websocket_event_handler, (void *)client);

    esp_websocket_client_start(client);
    xTimerStart(shutdown_signal_timer, portMAX_DELAY);
    char data[32];
    int i = 0;
    while (i < 5) {
        if (esp_websocket_client_is_connected(client)) {
            int len = sprintf(data, "hello %04d", i++);
            ESP_LOGI(TAG, "Sending %s", data);
            esp_websocket_client_send_text(client, data, len, portMAX_DELAY);
        }
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }

    ESP_LOGI(TAG, "Sending fragmented message");
    vTaskDelay(1000 / portTICK_PERIOD_MS);
    memset(data, 'a', sizeof(data));
    esp_websocket_client_send_text_partial(client, data, sizeof(data), portMAX_DELAY);
    memset(data, 'b', sizeof(data));
    esp_websocket_client_send_cont_msg(client, data, sizeof(data), portMAX_DELAY);
    esp_websocket_client_send_fin(client, portMAX_DELAY);

    xSemaphoreTake(shutdown_sema, portMAX_DELAY);
    esp_websocket_client_close(client, portMAX_DELAY);
    ESP_LOGI(TAG, "Websocket Stopped");
    esp_websocket_client_destroy(client);
}

void app_main(void)
{
    ESP_LOGI(TAG, "[APP] Startup..");
    ESP_LOGI(TAG, "[APP] Free memory: %" PRIu32 " bytes", esp_get_free_heap_size());
    ESP_LOGI(TAG, "[APP] IDF version: %s", esp_get_idf_version());
    esp_log_level_set("*", ESP_LOG_INFO);
    esp_log_level_set("websocket_client", ESP_LOG_DEBUG);
    esp_log_level_set("transport_ws", ESP_LOG_DEBUG);
    esp_log_level_set("trans_tcp", ESP_LOG_DEBUG);

    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());

    websocket_app_start();
}