乐鑫ESP32 https post请求

项目中遇到关于https的应用，例程中只有关于https的get，没有post，原以为只需要简单改动一下就能使用，但是实际调试过程中，发现不能用。 现在记录一下，防止忘记。
原例程是参照https_request_example_main.c文件中

https get

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(&https_get_task, "https_get_task", 8192, NULL, 5, NULL);
}

这个是主函数。其中的
ESP_ERROR_CHECK( nvs_flash_init() );
ESP_ERROR_CHECK(esp_netif_init());
ESP_ERROR_CHECK(esp_event_loop_create_default());
ESP_ERROR_CHECK(example_connect());
分别做了flash初始化，网络初始化，回调事件创建，以及网络连接。
如果已经建立了网络连接可以只调用ESP_ERROR_CHECK(esp_event_loop_create_default());
xTaskCreate(&https_get_task, “https_get_task”, 8192, NULL, 5, NULL);
这两个，就可以直接进行https的相关操作。

static void https_get_task(void *pvParameters)
{char buf[512];int ret, len;while(1) {esp_tls_cfg_t cfg = {.crt_bundle_attach = esp_crt_bundle_attach,};struct esp_tls *tls = esp_tls_conn_http_new(WEB_URL, &cfg);if(tls != NULL) {ESP_LOGI(TAG, "Connection established...");} else {ESP_LOGE(TAG, "Connection failed...");goto exit;}size_t written_bytes = 0;do {ret = esp_tls_conn_write(tls,REQUEST + written_bytes,strlen(REQUEST) - written_bytes);if (ret >= 0) {ESP_LOGI(TAG, "%d bytes written", ret);written_bytes += ret;} else if (ret != ESP_TLS_ERR_SSL_WANT_READ  && ret != ESP_TLS_ERR_SSL_WANT_WRITE) {ESP_LOGE(TAG, "esp_tls_conn_write  returned 0x%x", ret);goto exit;}} while(written_bytes < strlen(REQUEST));ESP_LOGI(TAG, "Reading HTTP response...");do{len = sizeof(buf) - 1;bzero(buf, sizeof(buf));ret = esp_tls_conn_read(tls, (char *)buf, len);if(ret == ESP_TLS_ERR_SSL_WANT_WRITE  || ret == ESP_TLS_ERR_SSL_WANT_READ)continue;if(ret < 0){ESP_LOGE(TAG, "esp_tls_conn_read  returned -0x%x", -ret);break;}if(ret == 0){ESP_LOGI(TAG, "connection closed");break;}len = ret;ESP_LOGD(TAG, "%d bytes read", len);/* Print response directly to stdout as it is read */for(int i = 0; i < len; i++) {putchar(buf[i]);}} while(1);exit:esp_tls_conn_delete(tls);putchar('\n'); // JSON output doesn't have a newline at endstatic int request_count;ESP_LOGI(TAG, "Completed %d requests", ++request_count);for(int countdown = 10; countdown >= 0; countdown--) {ESP_LOGI(TAG, "%d...", countdown);vTaskDelay(1000 / portTICK_PERIOD_MS);}ESP_LOGI(TAG, "Starting again!");}
}

https_get_task（）函数中，esp_tls_conn_http_new（）是通过url建立https的连接。esp_tls_conn_write（）完成传输，即通过TCP协议层传输https的header

例程中的协议头是这样的。

static const char *REQUEST = "GET " WEB_URL " HTTP/1.0\r\n""Host: "WEB_SERVER"\r\n""User-Agent: esp-idf/1.0 esp32\r\n""\r\n";

这里的WEB_SERVER，WEB_URL是用define定义的。（有一点需要注意的是，这种定义方式在Visual Studio中的C/C++会报错。）
下面的ret = esp_tls_conn_write(tls,
REQUEST + written_bytes,
strlen(REQUEST) - written_bytes);
是循环将header传输到对应的服务器上。
写完以后，开始等待http的回复。
后面进行回复读取：
bzero(buf, sizeof(buf));
ret = esp_tls_conn_read(tls, (char *)buf, len);
bzero（）类似于memset（），不过在http当中用的比较多。

https post

但是上面的例程是进行https get请求的，若进行post请求呢？
大多数情况下，post请求都是需要上传参数的。不管是text，xml，还是json。
body应该怎么填的？一开始我是这样做的。

const char *REQUEST = "POST " WEB_URL " HTTP/1.0\r\n""Host: " WEB_SERVER "\r\n""User-Agent: Mozilla/5.0\r\n""Content-Type:application/json\r\n""Accept-Encoding: gzip, deflate\r\n""Connection:keep-alive\r\n""Content-Length:360\r\n""Accept:*/*\r\n""\r\n";"{\r\n	\"appId\":	\"intelligent_cabinet\",\r\n	\"requestId\":	\"01831016-b18c-4a1e-a571\",\r\n	\"version\":	\"2.0\",\r\n	\"timestamp\":	\"1617325383000\",\r\n	\"sign\":	\"ZDJlNGJmZDQ4Y2MyOWNmOTU1ZDcyNTRkNzc3NDQwMzQwNzU1MGY2MQ==\"\r\n}";

格式是按照http的格式填充的，实际测试当中，发现body请求体并没有传到服务器。
后问了乐鑫的FAE，提示可以参考esp_http_client_example.c例程测试。
但是该例程当中也有不少的坑。
首先，这个例程当中包含多个请求方式，并且相当杂乱。

static void http_test_task(void *pvParameters)
{http_rest_with_url();http_rest_with_hostname_path();
#if CONFIG_ESP_HTTP_CLIENT_ENABLE_BASIC_AUTHhttp_auth_basic();http_auth_basic_redirect();
#endifhttp_auth_digest();http_relative_redirect();http_absolute_redirect();https_with_url();https_with_hostname_path();http_redirect_to_https();http_download_chunk();http_perform_as_stream_reader();https_async();https_with_invalid_url();http_native_request();ESP_LOGI(TAG, "Finish http example");vTaskDelete(NULL);
}

开始使用这个https_with_url();设置了一下，发现用不了，后面又调整了几次，终于发送成功了。
改的例程如下：

void https_with_url(void)
{char *outJson=NULL;char output_buffer[MAX_HTTP_OUTPUT_BUFFER] = {0};char request[512]={'\0'};outJson=rebuild_json();sprintf(request,"%s",outJson);free(outJson);esp_netif_init();esp_event_loop_create_default();esp_http_client_config_t config = {.url ="https://daily-robot.ele.me/bdi.robot_scheduler/v2/openapi/cater/order/prepared",.event_handler = http_event_handler,};esp_http_client_handle_t client = esp_http_client_init(&config);esp_http_client_set_method(client, HTTP_METHOD_POST);esp_http_client_set_header(client, "Content-Type", "application/json");esp_err_t err = esp_http_client_open(client, strlen(request));printf("https_with_url request =%s\n",request);if (err != ESP_OK) {ESP_LOGE(TAG, "Failed to open HTTP connection: %s", esp_err_to_name(err));} else {int wlen = esp_http_client_write(client, request, strlen(request));if (wlen < 0) {ESP_LOGE(TAG, "Write failed");}esp_err_t err = esp_http_client_perform(client);if (err == ESP_OK) {ESP_LOGI(TAG, "HTTPS Status = %d, content_length = %d",esp_http_client_get_status_code(client),esp_http_client_get_content_length(client));} else {ESP_LOGE(TAG, "Error perform http request %s", esp_err_to_name(err));}}esp_http_client_cleanup(client);
}

http回复的可以在http_event_handler（）函数中的
case HTTP_EVENT_ON_DATA:
后面打印一下：

case HTTP_EVENT_ON_DATA:ESP_LOGD(TAG, "HTTP_EVENT_ON_DATA, len=%d", evt->data_len);/**  Check for chunked encoding is added as the URL for chunked encoding used in this example returns binary data.*  However, event handler can also be used in case chunked encoding is used.*/if (!esp_http_client_is_chunked_response(evt->client)) {// If user_data buffer is configured, copy the response into the bufferif (evt->user_data) {memcpy(evt->user_data + output_len, evt->data, evt->data_len);} else {if (output_buffer == NULL) {output_buffer = (char *) malloc(esp_http_client_get_content_length(evt->client));output_len = 0;if (output_buffer == NULL) {ESP_LOGE(TAG, "Failed to allocate memory for output buffer");return ESP_FAIL;}}memcpy(output_buffer + output_len, evt->data, evt->data_len);}output_len += evt->data_len;}printf("output_buffer=%s\n",output_buffer);break;

跟postman上面的测试结果一致，后面就可以添加自己的数据处理拉，完成。
源码在这里：乐鑫ESP32 http post请求源码修改