Hello! I'm creating a Lua dissector to dissect custom packets that
contain header data and then other message-type-specific data. I made
dissectors for the header data and message-type data in separate Lua
files, and then want to call those dissectors from inside this one.
However, after I call the header dissector, it seems like the original
buffer data doesn't exist anymore - I get a "tvb expired" error when I
try to access the original buffer after calling the header dissector.
In my code below, the "1" Header dissector is called and works
correctly, but the subtree:add_le() calls after that give a "tvb
expired" error on buffer(). Is Lua's garbage collection destroying this
dissector's "buffer" variable when I call the header dissector? Is this
a bug (shouldn't I be able to call different dissectors on separate
parts of packet data)? Or am I doing something wrong here?
Thanks,
Matt
------------------------------------------------------------
dofile("testHeader.lua")
dofile("test700.lua")
test_proto = Proto("Test","TEST Protocol")
local msg_type = ProtoField.int32("Test.type", "Message Type", base.DEC)
local msg_size = ProtoField.int32("Test.size", "Message Size (bytes)",
base.DEC)
test_proto.fields = {msg_type, msg_size}
TestTable = DissectorTable.new("Test")
TestTable:add(1, testHeader_proto)
TestTable:add(700, test700_proto)
function test_proto.dissector(buffer,pinfo,tree)
pinfo.cols.protocol = "TEST"
local subtree = tree:add(test_proto, buffer(), "TEST Protocol")
local test_header = TestTable:get_dissector(1)
if test_header ~= nil then
test_header:call(buffer(0,14):tvb(), pinfo, subtree)
end
subtree:add_le(msg_type, buffer(14,4))
subtree:add_le(msg_size, buffer(18,4))
local msgtype = buffer(14,4):le_uint()
TestTable:try(msgtype, buffer(22):tvb(), pinfo, subtree)
end
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