NASHelperS1AP_DownlinkNasTransport.cpp

#include "NASHelperS1AP.hpp"

bool NASHelperS1AP::tryParseDownlinkNasTransportInformationElements(
    const std::uint8_t* const informationElements,
    const std::size_t informationElementOctetCount,
    DownlinkNasTransportInformationElementsParse& out) {
    out = DownlinkNasTransportInformationElementsParse{};

    if (informationElements == nullptr ||
        informationElementOctetCount < DownlinkNasTransportMandatoryFields::kNasMessageContainerLvMinTotalOctets) {
        return false;
    }

    const std::uint8_t valueLen = informationElements[0];
    const std::size_t totalLv = 1U + static_cast<std::size_t>(valueLen);
    if (totalLv < DownlinkNasTransportMandatoryFields::kNasMessageContainerLvMinTotalOctets ||
        totalLv > DownlinkNasTransportMandatoryFields::kNasMessageContainerLvMaxTotalOctets) {
        return false;
    }
    if (informationElementOctetCount < totalLv) {
        return false;
    }

    out.mandatory.nas_message_container_value = informationElements + 1U;
    out.mandatory.nas_message_container_value_octet_count = static_cast<std::size_t>(valueLen);
    out.mandatory.mandatory_total_octets = totalLv;
    out.unparsed_begin = informationElements + totalLv;
    out.unparsed_octet_count = informationElementOctetCount - totalLv;
    out.ok = true;
    return true;
}

bool NASHelperS1AP::tryParseUplinkNasTransportInformationElements(
    const std::uint8_t* const informationElements,
    const std::size_t informationElementOctetCount,
    UplinkNasTransportInformationElementsParse& out) {
    return tryParseDownlinkNasTransportInformationElements(informationElements, informationElementOctetCount, out);
}