static sgx_plat_error_t parse_svn_values()

in src/dcap_provider.cpp [777:831]

• 45 lines of code
• 6 McCabe index (conditional complexity)

static sgx_plat_error_t parse_svn_values(
    const curl_easy& curl,
    const nlohmann::json& json,
    sgx_ql_config_t* quote_config)
{
    sgx_plat_error_t result = SGX_PLAT_ERROR_OK;
    std::string tcb;
    result = extract_from_json(json, headers::TCB_INFO, &tcb);
    
    if (result != SGX_PLAT_ERROR_OK)
        return result;

    // string size == byte size * 2 (for hex-encoding)
    static constexpr size_t CPUSVN_SIZE =
        2 * sizeof(quote_config->cert_cpu_svn);
    static constexpr size_t PCESVN_SIZE =
        2 * sizeof(quote_config->cert_pce_isv_svn);

    if (tcb.size() != CPUSVN_SIZE + PCESVN_SIZE)
    {
        log(SGX_QL_LOG_ERROR, "TCB info header is malformed.");
        return SGX_PLAT_ERROR_UNEXPECTED_SERVER_RESPONSE;
    }

    const std::string cpu_svn_string = tcb.substr(0, CPUSVN_SIZE);
    log(SGX_QL_LOG_INFO, "CPU SVN: '%s", cpu_svn_string.c_str());
    if (const sgx_plat_error_t err =
            hex_decode(cpu_svn_string, &quote_config->cert_cpu_svn))
    {
        log(SGX_QL_LOG_ERROR, "CPU SVN is malformed.");
        return err;
    }

    const std::string pce_svn_string = tcb.substr(CPUSVN_SIZE, PCESVN_SIZE);
    log(SGX_QL_LOG_INFO, "PCE ISV SVN: '%s'.", pce_svn_string.c_str());
    if (const sgx_plat_error_t err =
            hex_decode(pce_svn_string, &quote_config->cert_pce_isv_svn))
    {
        log(SGX_QL_LOG_ERROR, "PCE ISV SVN is malformed.");
        return err;
    }

    if (is_little_endian()) // PCESVN is hosted in big-endian format for
                            // consistency with Intel
    {
        quote_config->cert_pce_isv_svn =
            byte_swap(quote_config->cert_pce_isv_svn);
    }

    log(SGX_QL_LOG_INFO,
        "PCE SVN parsed as '0x%04x'",
        quote_config->cert_pce_isv_svn);

    return SGX_PLAT_ERROR_OK;
}