char *https_request(const char *url, const char *payload, const char *cert_path, const char *key_path, const char *ca_path) { printf("test Register.vin "); printf("test Register.vin "); printf("test Register.vin "); printf("test Register.vin "); printf("test Register.vin "); SSL_library_init(); SSL_load_error_strings(); OpenSSL_add_all_algorithms(); // 加载 CA 证书 X509_STORE *store = X509_STORE_new(); X509_LOOKUP *lookup = X509_STORE_add_lookup(store, X509_LOOKUP_file()); X509_LOOKUP_load_file(lookup, ca_path, X509_FILETYPE_PEM); printf("test Register.vin "); // 加载客户端证书和私钥 SSL_CTX *ctx = SSL_CTX_new(TLS_method()); if (ctx == NULL) { perror("SSL_CTX_new"); return ("A"); } printf("test Register.vin "); // 设置支持的协议版本为 TLSv1.2 SSL_CTX_set_min_proto_version(ctx, TLS1_2_VERSION); SSL_CTX_set_max_proto_version(ctx, TLS1_2_VERSION); //SSL_CTX *ctx = SSL_CTX_new(TLSv1_2_client_method()); SSL_CTX_use_certificate_file(ctx, cert_path, SSL_FILETYPE_PEM); SSL_CTX_use_PrivateKey_file(ctx, key_path, SSL_FILETYPE_PEM); printf("test Register.vin "); // 创建 SSL 连接 SSL *ssl = SSL_new(ctx); // 解析 URL char host[256]; char path[4096]; int port = 443; if (sscanf(url, "https://%255[^/]/%4095s", host, path) != 2) { fprintf(stderr, "Error: Invalid URL\n"); return NULL; } // 创建 TCP 连接 int sockfd = socket(AF_INET, SOCK_STREAM, 0); struct sockaddr_in dest_addr; dest_addr.sin_family = AF_INET; dest_addr.sin_port = htons(port); dest_addr.sin_addr.s_addr = inet_addr(host); // 建立连接 connect(sockfd, (struct sockaddr *)&dest_addr, sizeof(dest_addr)); // 将 SSL 连接和 TCP 连接关联 SSL_set_fd(ssl, sockfd); // 进行 SSL 握手 SSL_connect(ssl); // 发送 HTTPS 请求 printf("test Register.vin "); char request[8192]; snprintf(request, sizeof(request), "POST %s HTTP/1.1\r\n" "Host: %s\r\n" "Content-Type: application/json\r\n" "Content-Length: %zu\r\n" "\r\n" "%s", path, host, strlen(payload), payload); SSL_write(ssl, request, strlen(request)); // 接收 HTTPS 响应 char buf[8192]; int bytes; size_t response_size = 0; char *response_buf = NULL; while ((bytes = SSL_read(ssl, buf, sizeof(buf))) > 0) { response_buf = realloc(response_buf, response_size + bytes + 1); memcpy(response_buf + response_size, buf, bytes); response_size += bytes; } response_buf[response_size] = '\0'; // 关闭 SSL 连接 SSL_shutdown(ssl); // 释放资源 SSL_free(ssl); close(sockfd); SSL_CTX_free(ctx); X509_STORE_free(store); ERR_free_strings(); printf("test Register.vin : %s\n", response_buf); return response_buf; } 怎么调用上面的函数，给出示例

假设我们想要调用上述函数，向某个 HTTPS 地址发送 POST 请求，请求体为 JSON 格式的字符串 payload，证书文件分别位于 cert_path、key_path 和 ca_path，示例如下：

char url[] = "https://example.com/foo/bar";
char payload[] = "{\"name\":\"John Doe\",\"age\":30}";
char cert_path[] = "/path/to/client/cert.pem";
char key_path[] = "/path/to/client/key.pem";
char ca_path[] = "/path/to/ca/cert.pem";
char *response = https_request(url, payload, cert_path, key_path, ca_path);
if (response == NULL) {
    printf("Error: Failed to send HTTPS request\n");
} else {
    printf("Response: %s\n", response);
    free(response);
}

其中，url 指定了目标地址，payload 指定了请求体，cert_path 和 key_path 分别指定了客户端证书和私钥的路径，ca_path 指定了 CA 证书的路径。如果函数调用成功，它将返回指向响应数据的指针，否则返回 NULL。需要注意的是，调用完毕后需要手动释放返回的指针，以避免内存泄漏。