Lua dissector is not processing the full TCP payload.

edit

Code:

function acses_protocol.dissector(tvb, pinfo, tree)

    -- tvb is the data buffer that contains all of the message information. Reference the information with tvb(x, y) 
    -- where x is the starting position and y is the length to read (in bytes). Therefore, if the frame has no length, 
    -- then exit the dissector
    local frame_len = tvb:len()
    if frame_len == 0  then return end

    -- Create the GIU tab for ACSES information
    _G.subtree = tree:add(acses_protocol, tvb(), "ACSES Protocol Data")

    -- Add ACSES to the "Protocol" column in Wireshark
    pinfo.cols.protocol = acses_protocol.name ..":"

    --check for the weird split message
    if frame_len == 6 then 
        if (tvb(0, 4):uint() == 0xfff555ff) then 
            acsesHeader = tvb(0, 4):uint()
            acsesLength = tvb(4, 2):uint()
            subtree:add(f.isSplitMessage, true)
            pinfo.cols.protocol = tostring(pinfo.cols.protocol) .. " [SPLIT MESSAGE]" 
            return
        end
    end


    -- Process the payload from beginning to end looking for ACSES messages
    -- since there may be more than 1 in a message.
    local msg_cnt = 0

    for i = 0, frame_len - 4, 1 do
        -- Determine if the message is an ACSES Message
        if tvb(i, 4):uint() == 0xfff555ff or (acsesHeader == 0xfff555ff and tvb(i, 4):uint() ~= 0xfff555ff and i == 0) then
            -- Add a separator between messages when there is more than 1 
            -- submessage embedded in a larger message
            if (msg_cnt > 0) then
                subtree:add(f.test_s, "###", "**************************************************", " ")
            end

            -- get the message length from the buffer or get it from the previous message buffer
            if acsesLength ~= 0 and tvb(i, 4):uint() ~= 0xfff555ff and i == 0 then
                msg_len = acsesLength
                i = i-6
                --reset the previous message buffers
                acsesLength = 0
                acsesHeader = 0
                bufferFlag_ResetI = 1
                splitFlag = 1
            else
                msg_len = tvb(i + 4, 2):uint()
            end

            -- Determine if the message is a Maintience Train Alarm or Maintience Train Ack
            -- because they have the message label in a different location. For some unearthly reason.
            -- Also, check to see if the source address is 0, because if it is, that means it's a tsr response, but structured differently
            local msg_index = 0
            if ((msg_len == 36) or (msg_len == 58)) then
                msg_index = i + 27
            elseif tvb(i+8, 4):uint() == 0x00000a14 then
                msg_index = i + 20
            else
                msg_index = i + 25
            end

            -- It seems that the only defining feature of a self addressed message is its length
            -- otherwise, use the label. 
            if (msg_len == 15) then
                msg_lbl = 0
                msg_type = "Self_Addressed_Message"
                subtree:add(f.isSelfAddrMsg, true)
            else
                msg_lbl = tvb(msg_index, 2):uint()
                msg_type = label_msg_type(msg_lbl)
            end

            --Add the message type to the protocol column
            pinfo.cols.protocol = tostring(pinfo.cols.protocol) .. " " .. msg_type .. " (" .. msgtocode(msg_lbl) .. ")" 

            -- Output the message type to the top of the tree before dissecting the rest of the message
            subtree:append_text(" (" .. msg_type .. ") ")

            --[[Functions located in ixl.lua]]--
            if (msg_type == "IXL_Status_Request") then 
                ixl.ixl_request(tvb(i + 6, msg_len))

            --[[Functions located in wiu.lua]]--
            elseif (msg_type == "WIU_Response_w_LoMA") then
                wiu_resp_w_loma(tvb(i + 6, msg_len))
            elseif (msg_type == "WIU_Response_wo_LoMA") then
                wiu_resp_wo_loma(tvb(i + 6, msg_len))
            elseif (msg_type == "WIU_Error_Response") then
                wiu_error(tvb(i + 6, msg_len))

            --[[Functions located in tsr.lua]]--
            elseif tvb(i+8, 4):uint() == 0x00000a14 then
                tsr.tsr_answer_alt(tvb(i + 6, msg_len))
            elseif ...