problem in adding message in wireshark tree

[Awadhesh Kumar <awadhesh.usa () gmail com>]

Hi,
I am writing LUA disectors for Wireshark packets. I am seeing that my
disectors are getting called multiple times for a packet. I am calculating
udp packet length as below

udp_len_f = Field.new("udp.length")

function InDirectmip_proto.dissector(buffer,pinfo,tree)

        print(udp_len_f ( ))

end

But in next call of disectors, udp length is coming "nil". I don't know for
what packet this is getting called?

Also I have created tree to add my own user defined information in wireshark
tree as

stmpsecuritytree = tree:add(InDirectmip_proto,buffer(),"STMP SECURITY
HEADER");
stmptree = tree:add(InDirectmip_proto,buffer(),"STMP DATA HEADER");
subtree = tree:add(InDirectmip_proto,buffer(),"ST DATA")

res, status = pcall (udp_len_f )

if( res) then

stmpsecuritytree:add(buffer(0,1)," STMP Message length: " .. udp_len_f());

else
print (" I got exception");

end

Here at call of pcall (udp_len_f ) , res is printing as false in second
call. It means function udp_len_f () has thrown exception in second call.
Due to this exception message "STMP Message length" is not added in the
wireshark tree.


I want to handle the exception in following if failed in lua when I am
calling above API.

                stmpsecuritytree:add(buffer(0,1)," STMP Message length: " ..
udp_len_f());


 How can I stop the wireshark/LUA library which restricts to
call dissectors multiple times?

Please help me in this regard.

Thanks in Advance
Awadhesh.

P.S. I asked this problem on LUA support group, they suggested me to post
this on wireshark group.

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