Rednet Spam Monitor Node

local pos = {5275, 69, 2162}
local operatingChannel = 26743

local messageList = {}

local modem = nil
for k,v in pairs(rs.getSides()) do
    if peripheral.getType(v) == "modem" then
        modem = peripheral.wrap(v)
        break
    end
end

if not modem then
    print("No modem found!")
    return
end

modem.open(operatingChannel)
modem.open(rednet.CHANNEL_REPEAT)
modem.open(gps.CHANNEL_GPS)

local getDistance = function(id)
    for k,v in pairs(messageList) do
        if v.id == id then
            return v.dist
        end
    end
    return false
end

print("Running Rednet Spam Locator Node")
print("At position: "..pos[1]..", "..pos[2]..", "..pos[3])

while true do
    local event, side, channel, reply, message, dist = os.pullEvent()
    if event == "modem_message" and channel == rednet.CHANNEL_REPEAT and type(message) == "table" then
        if message.nMessageID and message.nRecipient and not getDistance(message.nMessageID) then
            table.insert(messageList, {dist = dist, id = message.nMessageID})
            if #messageList > 200 then
                table.remove(messageList, 1)
            end
        end
    elseif event == "modem_message" and type(message) == "table" and message.ddosMonitor then
        if message.ddosMonitor == "request" and message.messageID then
            local dist = getDistance(message.messageID)
            if dist then
                modem.transmit(operatingChannel, operatingChannel, {x = pos[1], y = pos[2], z = pos[3], dist = dist,
                id = message.messageID, ddosMonitor = "response"})
            end
        end
    elseif event == "modem_message" and channel == gps.CHANNEL_GPS and message == "PING" then
        modem.transmit(reply, gps.CHANNEL_GPS, {pos[1], pos[2], pos[3]})
    end
end