如何解决ESP32使用Twilio API时的ESP-TLS连接错误？

开发板可正常连接WiFi，但调用Twilio API发送SMS时出现以下TLS错误，无法建立连接：

E (30400) esp-tls-mbedtls: No server verification option set in esp_tls_cfg_t structure. Check esp_tls API reference
E (30400) esp-tls-mbedtls: Failed to set client configurations, returned [0x8017] (ESP_ERR_MBEDTLS_SSL_SETUP_FAILED)
E (30400) esp-tls-mbedtls: No server verification option set in esp_tls_cfg_t structure. Check esp_tls API reference
E (30420) esp-tls: create_ssl_handle failed
E (30430) esp-tls: Failed to open new connection

E (30480) HTTP_CLIENT: Connection failed, sock < 0

已在sdkconfig中设置Allow potentially insecure options和Skip server certificate verification by default（SDK配置编辑器及sdkconfig文件均已修改）。

当前客户端配置代码：

esp_http_client_config_t config = {
    .url = twilio_url,
    .method = HTTP_METHOD_POST,
    .auth_type = HTTP_AUTH_TYPE_BASIC,
};

esp_http_client_handle_t client = esp_http_client_init(&config);
esp_http_client_set_header(client, "Content-Type", "application/x-www-form-urlencoded");
esp_http_client_set_username(client, account_sid);
esp_http_client_set_password(client, auth_token);

解决方案 #

即使全局设置了跳过证书验证，仍需在esp_http_client_config_t中显式指定TLS验证选项，否则ESP-TLS会因未配置验证策略而报错。修改配置结构体，添加以下参数：

esp_http_client_config_t config = {
    .url = twilio_url,
    .method = HTTP_METHOD_POST,
    .auth_type = HTTP_AUTH_TYPE_BASIC,
    .skip_cert_common_name_check = true, // 跳过证书通用名检查
    .tls_cfg = {
        .verify_certificate = false, // 禁用服务器证书验证
    },
};

说明 #

• verify_certificate = false 直接禁用证书验证，匹配全局设置的“Skip server certificate verification by default”
• skip_cert_common_name_check = true 跳过证书通用名与URL域名的匹配检查，避免因域名不匹配导致的验证失败

修改后重新编译烧录，即可正常建立TLS连接并发送SMS。

内容的提问来源于stack exchange，提问作者Chandler Thornton