Hi,
I've been using Lua to create a dissector for a protocol that has IP encapsulated inside TCP with an additional header. Everything works fine until I try to create a new tvb off from a tvbsubrange. When I do this, Wireshark crashes. The new tvb appeared correct when I added debug statements (pointing at the correct data, and length are correct).
The Lua and Wireshark docs refered to the Tvb.new_subset function to create a new sub tvb for an encapsulated protocol. I couldn't get that to work and used something like buffer(4,n):tvb().
I've only been looking at the Wireshark and Lua code for a short time now, so I'm hoping I'm just coding something up wrong. Any pointers would be greatly appreciated.
Here's a sample of the code that was crashing. If I comment out the line that tries to pass the new sub tvb to the ip dissector, or just pass the original buffer to the ip dissector, wireshark doesn't crash (although it doesn't decode like I need it too)
Thanks.
-Scott
-- Define our protocol
my_proto = Proto("myproto", "MINE", "My Protocol")
-- Create a function to dissect my_proto
function my_proto.dissector( buffer, pinfo, tree )
local subtree = tree:add( my_proto, buffer, "My Proto Header" )
subtree:add( buffer(0,1), "Version: " .. buffer(0,1):uint() )
subtree:add( buffer(1,1), "Type: " .. buffer(1,1):uint() )
subtree:add( buffer(2,2), "Sequence: " .. buffer(2,2):uint() )
ip_dissector = Dissector.get("ip")
-- skip over the header in front of the encapsulated ip packet
sub_buf = buffer( 4, buffer:len() - 4 ):tvb()
ip_dissector:call( sub_buf, pinfo, tree )
end
-- load the tcp port table
tcp_table = DissectorTable.get("tcp.port")
-- register our protocol
tcp_table:add(7000, my_proto)