Issue about tvb_reported_length_remaining() and tvb_captured_length_remaining() of tvb passed from Lua

["qiangxiong.huang" <qiangxiong.huang () qq com>]

Hi, 

I reproduced this issue (https://gitlab.com/wireshark/wireshark/-/issues/17255) in windows. It report error like this:
 User Datagram Protocol, Src Port: 54046, Dst Port: 8129 Tutorial AddressBook Encapsulated With CRC     Magic: ADDR     
Data Length: 157     CRC: 2831742514 -- Actually, this field is after the tutorial.AddressBook field     Payload 
tutorial.AddressBook (real: 157 bytes, reported: 161 bytes, remaining:  161 bytes)     Protocol Buffers: 
tutorial.AddressBook -- 157 bytes [Packet size limited during capture: ProtoBuf truncated] --**actually, only 157 bytes 
in tvb, but reported_length(_remaining) is 161 bytes** 
Problem will disappear if I replace the tvb_reported_length_remaining in 
https://gitlab.com/wireshark/wireshark/-/blob/master/epan/dissectors/packet-protobuf.c#L1427 with 
tvb_captured_length_remaining.
 
But I'm not sure if the bug is in the code about Lua or packet-protobu.c. Because I think the captured_length of the 
sub tvb passed from lua to protobuf dissector should equal to reported_length if there's no truncate data in UDP packet.

The UDP data format of frame No.11 of 
https://gitlab.com/wireshark/wireshark/uploads/690b015d92e14b48a06591e298210eae/addrbook_simple.pcap is:
 |<- 4 bytes -&gt;|<--- 4 bytes ----&gt;|<------ 157 bytes ------&gt;|<- 4 bytes -&gt;|  
-------------------------------------------------------------------------- | Magic: ADDR | Data Length: 157 | Payload 
(Protobuf Data) |     CRC     | -------------------------------------------------------------------------- 
Lua call protobuf dissector by code:
     local req_len = tvb(4,4):uint()     -- req_len is 157     local payload = tvb(4+4,req_len)     local payload_tvb = 
payload:tvb()     pcall(Dissector.call, protobuf_dissector, payload_tvb, pinfo, subtree) 
Try to print in lua:
  
 payload_tvb:len() is 157 bytes
 
 payload_tvb:reported_len() is 161 bytes
 
 payload_tvb:reported_length_remaining() 161 bytes (**I think reported_len() and remaining reported length (from offset 
0) must equal to len() here**)
  
Try to print in protobuf:
  
 tvb_captured_length(tvb) is 157 bytes
 
 tvb_reported_length_remaining(tvb, 0) is 161 bytes (**that cause the parsing failure**).
  
Where is the bug? If it a bug belongs to packet-protobuf.c, I can submit a merge for it. But If it belongs to 
wslua_tvb.c, who familiar with the code&nbsp;wslua_tvb.c&nbsp;may help fix.

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