[Bugs] NAS message format doesn't follow spec

[ss920386]

Describe the bug

According to 3GPP TS 24.502 section 8.2, NAS messages over control plane should be transported over TCP connection by encapsulating the NAS message into TCP packets. However, the non-3gpp UE here seems to use an UL NAS TRANSPORT message other than an ESP packet encapsulating NAS message.

Expected behavior

Use ESP packet encapsulating NAS message for Registration Complete and PDU Session Setup Request message.

Screenshots

Instead of using UL NAS TRANSPORT message (3GPP TS 24.501),

using ESP packet for TCP packet encapsulating NAS message is preferable according to 3GPP TS 24.502.

Trace File

my5G-non3GPP-access/ue_procedures/registration.go

Registration Complete

// send NAS Registration Complete Msg
pdu = nasTestpacket.GetRegistrationComplete(nil)
pdu, err = EncodeNasPduWithSecurity(ue, pdu, nas.SecurityHeaderTypeIntegrityProtectedAndCiphered, true, false)

PDU Session Setup Request

pdu = nasTestpacket.GetUlNasTransport_PduSessionEstablishmentRequest(10, nasMessage.ULNASTransportRequestTypeInitialRequest, "internet", &sNssai)`
pdu, err = EncodeNasPduWithSecurity(ue, pdu, nas.SecurityHeaderTypeIntegrityProtectedAndCiphered, true, false)