Listening for a rednet message being sent

I'm attempting to display the in/out packets to a computer, just to monitor when things are connecting to it or if it's connecting to something. However, I've run into a problem monitoring packets being sent out. I've looked through several APIs and looked but there was nothing I could do with os.pullEvent to listen for the modem sending a message. So are there any events I could listen for to do this that I overlooked? Or would I have to implement it in every external program that sends rednet messages in the computer?

You'll indeed require your own listener, best I can make out.

I guess a really simple way to do this would be to implement a global function and a global variable in your monitoring program. Have your other programs call the function whenever they want to send something and let that send it, while incrementing the variable.

Bomb Bloke, on 28 May 2013 - 10:01 PM said:

I guess a really simple way to do this would be to implement a global function and a global variable in your monitoring program. Have your other programs call the function whenever they want to send something and let that send it, while incrementing the variable.

+1 I agree for this situation. You could override peripheral.wrap to check if the peripheral being wrapped is a modem and, from there, override the transmit function which is in the table returned by peripheral.wrap when wrapping a modem.

Here's a code example:

_G.lastTransmitCallData = {} -- All of the parameters to the last call to the wrapped transmit will be put here.
local oldWrap           = _G.peripheral.wrap -- The 'true' peripheral.wrap function.

_G.peripheral.wrap = function (side)
    -- If the peripheral being wrapped is a modem then make some changes
    -- to the modem handle before returning it.
    if peripheral.getType (side) == "modem" then
        local modemHandle = oldWrap (side)
        local oldTransmit = modemHandle.transmit

        -- Override the transmit function for the modem which has been wrapped.
        modemHandle.transmit = function ( ... )
            _G.lastTransmitCallData = { ... }
            oldTransmit ( ... )
        end

        -- Return the modified modem handle.
        return modemHandle
    end

    -- If the peripheral wasn't a modem then behave normally.
    return oldWrap (side)
end