Rednet Relay

-- Variables
local turtleIDs = { ['3'] = true, ['6'] = true } -- table with all the turtle IDs that are in use for the program

function split(str, divider)
	local parts = {}
	for v in str:gmatch('[^'..divider..']+') do
		table.insert(parts, v)
	end
	return parts
end

local function receiveRednet()
	local sID, msg, temp
	repeat
		sID, msg = rednet.receive()
		temp = split( msg, '_' )
		-- what a client pc could send in a rednet message
		-- can be something like this for easy use:
		-- 'client_turtleid_message'
		-- temp[1] will be client
		-- temp[2] will be the id of the turtle
		-- temp[3] will be the message
	until turtleIDs[temp[2]] -- so it will keep doing it until a message is received that has a legit turtle ID
	-- okay, so legit turtle id detected, lets forward the message
	-- to the turtle
	-- but first return the variables
	return { client = temp[1], turtleid = temp[2], msg = temp[3] } -- returns a table with the correct details
end

while true do -- infinite loop
	term.clear()
	term.setCursorPos(1,1)
	print('Waiting for a rednet response...')
	local info = receiveRednet()
	-- If it got here, then there is a legit turtle id
	-- now let's send the message to the turtle
	local s = info[1] .. '_' .. info[3] -- string to send, separated with a _ for splitting, format: 'client_message'
	rednet.send(tonumber(info[2]), s) -- sends the string to the turtle
end

-- Variables
local turtleIDs = { ['3'] = true, ['6'] = true } -- table with all the turtle IDs that are in use for the program
local serverID = 1 -- the id of the server
-- you could just have the server to just respond success or failure,
-- but that means more rednet is involved ...

local function sWrite( str, x, y )
	term.setCursorPos( x, y )
	write( str )
end

local function getValue( x, y )
	term.setCursorPos( x, y )
	return read()
end

while true do
	term.clear()
	sWrite( '  Client: ', 1, 1 )
	sWrite( 'TurtleID: ', 1, 2 )
	sWrite( ' Message: ', 1, 3 )
	local client = getValue( 11, 1 ) .. '[' .. os.getComputerID() .. ']' -- name with the computer's ID in brackets at the end
	local turtleID = getValue( 11, 2 )
	local message = getValue( 11, 3 )
	if turtleIDs[turtleID] then -- check if it is a valid turtle id
		print( '\nSuccess!')
		local s = client .. '_' .. turtleID .. '_' .. message
		rednet.send( serverID, s )
	else
		print( '\nInvalid Turtle ID!')
	end
	sleep(1.3)
end