c - libcurl:http 响应状态代码始终为 NULL？

Question

我正在使用 libcurl 7.29.0。

当服务器运行时，我所有的测试用例都工作正常，但当服务器不可访问时，我收到一个CURLE_HTTP_RETURNED_ERROR错误。

在这种情况下，我总是收到 CURLE_COULDNT_CONNECT curl 错误，并且 HTTP 响应代码为 0。

根据我的要求，我需要 HTTP 响应代码。请提出一些解决方案，在此先感谢。

下面附上了我用来发布数据的 API。

int http_curl_post_response(char *url, char *post_data, char *response,
                            long int *responseCode) {
    CURL *ps_curl;
    CURLcode curl_status = CURLE_OK;
    struct curl_slist *headers = NULL; /* http headers to send with request */

    /* get a curl handle */
    ps_curl = curl_easy_init();
    if (ps_curl) {
        /* set content type */
        headers = curl_slist_append(headers, "Accept: application/json");
        headers = curl_slist_append(headers, "Content-Type: application/json");
        headers = curl_slist_append(headers, "charsets: utf-8");

        /* This is to intialize respone from curl */
        http_curl_respone ps_response;

        curl_easy_setopt(ps_curl, CURLOPT_URL, url);

        curl_easy_setopt(ps_curl, CURLOPT_HTTPHEADER, headers);

        curl_easy_setopt(ps_curl, CURLOPT_POSTFIELDS, post_data);

        curl_easy_setopt(ps_curl, CURLOPT_POSTFIELDSIZE, -1L);

        curl_easy_setopt(ps_curl, CURLOPT_FOLLOWLOCATION, 1L);

        /* This is to read response from curl */
        curl_easy_setopt(ps_curl, CURLOPT_WRITEFUNCTION, write_response_json);

        init_response(&ps_response);
        if (ps_response.pi1_response == NULL) {
            i4_curl_status = MEM_ALLOC_ERROR;
            goto HTTP_CURL_ERROR;
        }

        curl_easy_setopt(ps_curl, CURLOPT_WRITEDATA, &ps_response);

        curl_easy_setopt(ps_curl, CURLOPT_FAILONERROR, 1L);

        /* Perform the request, i4_curl_status will get the return code */
        curl_status = curl_easy_perform(ps_curl);
        if (curl_status != CURLE_OK) {
            if (curl_status == CURLE_HTTP_RETURNED_ERROR) {
                curl_easy_getinfo(ps_curl, CURLINFO_RESPONSE_CODE,
                                  responseCode);
                /* always cleanup */
                curl_easy_cleanup(ps_curl);
            }
            goto HTTP_CURL_ERROR;
        } else {
            memcpy(response, ps_response.pi1_response, ps_response.s_len);
            response[ps_response.s_len] = '\0';
        }

        /* always cleanup */
        curl_easy_cleanup(ps_curl);
        /* free headers */
        curl_slist_free_all(headers);

    HTTP_MEM_ERROR:
        if (ps_response.pi1_response) free(ps_response.pi1_response);
    } else {
        curl_status = CURLE_FAILED_INIT;
    }

HTTP_CURL_ERROR:

    return curl_status;
}

Answer 1

... but when the server is not reachable I'm receiving a CURLE_HTTP_RETURNED_ERROR error.In this scenario I'm always getting a CURLE_COULDNT_CONNECT curl error and the HTTP response code is 0.

如果服务器不可访问且连接失败，检查响应代码甚至没有意义。 response code是 HTTP 响应的属性。它记录在 HTTP 服务器发回的部分 HTTP 响应(status line)中，以回复 libcurl 代表您发送的 HTTP 请求。如果没有连接，说明服务器没有收到你的请求，没有响应可言!

Based on my requirement I want the HTTP response code.

如果没有连接，则没有响应 - 因此没有响应代码。

在这种情况下，您可以将 local responseCode 变量设置为 -1 以指示连接失败:

*responseCode = -1;