当服务器不可访问时 curl_easy_perform 返回 -1

Question

当我尝试对无法访问的服务器执行一些 HTTP_POST、HTTP_DELETE 操作时，返回码有时会显示为 -1。因为我的应用程序正在崩溃。

这是我的示例代码。

我的应用程序代码在 c++ 中，我也在其中读取响应和响应标头。

  lCode = curl_easy_setopt(curlHandle, CURLOPT_HEADERFUNCTION,
                                      HttpClientImplCurl::recvFunctionHeader);

    if (lCode != CURLE_OK) {
        LOG(LOG_CRIT, "CURL failure: curl_easy_setopt CURLOPT_HEADERFUNCTION returned %d\n", lCode);
        curl_slist_free_all(lHeaders);
        errorBuff = curl_easy_strerror(lCode);
        return http_code;

    }


    lCode = curl_easy_setopt(curlHandle, CURLOPT_WRITEHEADER,
                                      &readResHeaderBuffer);

    if (lCode != CURLE_OK) {
        LOG(LOG_CRIT, "CURL failure: curl_easy_setopt CURLOPT_WRITEHEADER returned %d\n", lCode);
        curl_slist_free_all(lHeaders);
        errorBuff = curl_easy_strerror(lCode);
        return http_code;

    }

        lCode = curl_easy_setopt(curlHandle, CURLOPT_WRITEFUNCTION,
                             HttpClientImplCurl::recvFunction);

    if (lCode != CURLE_OK) {
        LOG(LOG_CRIT, "CURL failure: curl_easy_setopt WRITEFUNCTION returned %d\n", lCode);
        curl_slist_free_all(lHeaders);
        errorBuff = curl_easy_strerror(lCode);
        return http_code;

    }

    lCode = curl_easy_setopt(curlHandle, CURLOPT_WRITEDATA,
                             &readResBuffer);

    if (lCode != CURLE_OK) {
        LOG(LOG_CRIT, "CURL failure: curl_easy_setopt WRITEDATA returned %d\n", lCode);
        curl_slist_free_all(lHeaders);
        errorBuff = curl_easy_strerror(lCode);
        return http_code;

    }

    lCode = curl_easy_setopt(curlHandle, CURLOPT_CUSTOMREQUEST, "DELETE"); /* !!! */

    if (lCode != CURLE_OK) {
        LOG(LOG_CRIT, "CURL failure: curl_easy_setopt CURLOPT_CUSTOMREQUEST returned %d\n", lCode);
        curl_slist_free_all(lHeaders);
        errorBuff = curl_easy_strerror(lCode);
        return http_code;

    }

    lCode =  curl_easy_setopt(curlHandle, CURLOPT_POSTFIELDS, aInRemovedata.getBuffer()); /* data goes here */

    if (lCode != CURLE_OK) {
        LOG(LOG_CRIT, "CURL failure: curl_easy_setopt CURLOPT_POSTFIELDS  returned %d\n", lCode);
        curl_slist_free_all(lHeaders);
        errorBuff = curl_easy_strerror(lCode);
        return http_code;

    }

lCode = curl_easy_perform(curlHandle);


    if (lCode != CURLE_OK) {
        LOG(LOG_CRIT, "CURL failure: curl_easy_perform returned %d\n", lCode);
        curl_slist_free_all(lHeaders);
        errorBuff = curl_easy_strerror(lCode);---->my doubt is when i am geting "-1", this line is caused the crash.
        return http_code;
    }

而我的回调如下，

  size_t
HttpClientImplCurl::recvFunctionHeader(void *aInBuf, size_t aInSize,
                                size_t aInNmemb, void* aInUserp)
{
    fprintf(stderr, "curl error: too small buffer in recv2\n");
    ((std::string*)aInUserp)->append((char*)aInBuf, aInSize * aInNmemb);
    return aInSize * aInNmemb;
}


// Private static callback
size_t
HttpClientImplCurl::recvFunction(void *aInBuf, size_t aInSize,
                                size_t aInNmemb, void* aInUserp)
{
    fprintf(stderr, "curl error: too small buffer in recv1\n");
    ((std::string*)aInUserp)->append((char*)aInBuf, aInSize * aInNmemb);
    return aInSize * aInNmemb;
}

请帮助我，为什么我们偶尔会用“-1”代替“28”。

这是函数签名，errorBuf作为参数传入

 int
HttpClientImplCurl::put(const HttpClient& aInClient,const base::Buffer& aInPutdata,
                          base::Buffer& aOutRecvBuf,base::Buffer&  aOutRecvHeaderBuf,const char*& errorBuff)

Answer 1

您可以尝试设置 CURLOPT_ERRORBUFFER 和 CURLOPT_VERBOSE 以获取有关 curl_easy_perform 返回的值为何为 -1 的更多信息。