PNIOServiceReqPDU Layer doesn't compute length parameters

Brief description

The args_max, args_length, max_count and actual_count parameters of layer PNIOServiceReqPDU are not automatically computed when I try to sent a implicite Read Request.

Scapy version

2.5.0

Python version

3.11

Operating system

Windows Version 10.0.19045 Build 19045

Additional environment information

No response

How to reproduce

ReadPacket = scapy.all.Ether() / scapy.all.IP(dst=192.168.1.3) / scapy.all.UDP(dport=49152, sport=59832) / scapy.all.DceRpc4(
            rpc_vers=4, ptype=0, flags1=0x28, flags2=0x00, object=0xdea000006c9711d182710001fff1011e, endian=0, if_id=0xdea000016c9711d1827100a02442df7d, act_id=0x9bf6098164c5452fa410d885d4e300d1, opnum=5,  seqnum=rpc_seqnum
        )/scapy.contrib.pnio_rpc.PNIOServiceReqPDU()/scapy.contrib.pnio_rpc.IODReadReq(
            block_length=60, seqNum=1, slotNumber=0, subslotNumber=1, index=0xAFF1, recordDataLength=4096)
        ReadPacket.show() #ReadPacket.show2() doesn't show anything different
        scapy.all.sendp(ReadPacket, iface=interface)
#replace interface with your interface

Actual result

###[ PNIOServiceReqPDU ]###
              args_max  = None
              args_length= None
              max_count = None
              offset    = 0
              actual_count= None
              \blocks    \

Expected result

###[ PNIOServiceReqPDU ]###
              args_max  = 1392
              args_length= 64
              max_count = 1392
              offset    = 0
              actual_count= 64
              \blocks    \

Related resources

PNIO Bug Report.zip

Start by inspecting the PNIOServiceReqPDU and IODReadReq definitions, then run the supplied Python reproduction with the packet's show output. Trace how the request fields determine args_max, args_length, max_count, and actual_count; done means these values are computed as expected for the example request.