std::string Util::GetIMDSToken()

in cvm-securekey-release-app/AttestationUtil.cpp [218:287]
56 lines of code
8 McCabe index (conditional complexity)

std::string Util::GetIMDSToken(const std::string &KEKUrl)
{
    TRACE_OUT("Entering Util::GetIMDSToken()");

    CURL *curl = curl_easy_init();
    if (!curl)
    {
        TRACE_ERROR_EXIT("curl_easy_init() failed")
    }

    // AKV and mHSM has different audience need to be passed to IMDS.
    std::string resourceUrl = getResourceUrl(KEKUrl);
    CURLcode curlRet = curl_easy_setopt(curl, CURLOPT_URL, GetImdsTokenUrl(resourceUrl).c_str());
    if (curlRet != CURLE_OK)
    {
        TRACE_ERROR_EXIT("curl_easy_setopt() failed")
    }

    // ByPassing proxy for IMDS.
    // ref: https://learn.microsoft.com/en-us/azure/virtual-machines/instance-metadata-service?tabs=windows
    curlRet = curl_easy_setopt(curl, CURLOPT_PROXY, "");
    if (curlRet != CURLE_OK)
    {
        std::ostringstream oss;
        oss << "curl_easy_setopt() failed: " << curl_easy_strerror(curlRet);
        TRACE_ERROR_EXIT(oss.str().c_str())
    }

    struct curl_slist *headers = NULL;
    headers = curl_slist_append(headers, "Metadata: true");
    curlRet = curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
    if (curlRet != CURLE_OK)
    {
        TRACE_ERROR_EXIT("curl_easy_setopt() failed\n")
    }

    curlRet = curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, CurlWriteCallback);
    if (curlRet != CURLE_OK)
    {
        TRACE_ERROR_EXIT("curl_easy_setopt() failed")
    }

    std::string responseStr;
    curlRet = curl_easy_setopt(curl, CURLOPT_WRITEDATA, &responseStr);
    if (curlRet != CURLE_OK)
    {
        std::ostringstream oss;
        oss << "curl_easy_setopt() failed: " << curl_easy_strerror(curlRet);
        TRACE_ERROR_EXIT(oss.str().c_str())
    }

    curlRet = curl_easy_perform(curl);
    if (curlRet != CURLE_OK)
    {
        std::ostringstream oss;
        oss << "curl_easy_perform() failed: " << curl_easy_strerror(curlRet);
        TRACE_ERROR_EXIT(oss.str().c_str())
    }

    curl_easy_cleanup(curl);
    TRACE_OUT("Response: %s\n", Util::reduct_log(responseStr).c_str());
    json json_object = json::parse(responseStr.c_str());
    std::string access_token = json_object["access_token"].get<std::string>();

    TRACE_OUT("Access Token: %s\n", Util::reduct_log(access_token).c_str());

    TRACE_OUT("Exiting Util::GetIMDSToken()");

    return access_token;
}