redProxy

CHANNEL_BROADCAST = 65535
CHANNEL_REPEAT = 65533
proxyid = 999
local tReceivedMessages = {}
local tReceivedMessageTimeouts = {}
local tHostnames = {}
function setID(id)
    proxyid = id
end

local function isOpen( sModem )
    if sModem then
        -- Check if a specific modem is open
        if type( sModem ) ~= "string" then
            error( "expected string", 2 )
        end
        if peripheral.getType( sModem ) == "modem" then
            return peripheral.call( sModem, "isOpen", os.getComputerID() ) and peripheral.call( sModem, "isOpen", CHANNEL_BROADCAST )
        end
    else
        -- Check if any modem is open
        for n,sModem in ipairs( peripheral.getNames() ) do
            if isOpen( sModem ) then
                return true
            end
        end
    end
    return false
end

function send( nRecipient, message, sProtocol )
    -- Generate a (probably) unique message ID
    -- We could do other things to guarantee uniqueness, but we really don't need to
    -- Store it to ensure we don't get our own messages back
    local nMessageID = math.random( 1, 2147483647 )
    tReceivedMessages[ nMessageID ] = true
    tReceivedMessageTimeouts[ os.startTimer( 30 ) ] = nMessageID

    -- Create the message
    local nReplyChannel = proxyid
    local tMessage = {
        nMessageID = nMessageID,
        nRecipient = nRecipient,
        message = message,
        sProtocol = sProtocol,
    }

    if nRecipient == os.getComputerID() then
        -- Loopback to ourselves
        os.queueEvent( "rednet_message", nReplyChannel, message, sProtocol )

    else
        -- Send on all open modems, to the target and to repeaters
        local sent = false
        for n,sModem in ipairs( peripheral.getNames() ) do
            if isOpen( sModem ) then
                peripheral.call( sModem, "transmit", nRecipient, nReplyChannel, tMessage );
                peripheral.call( sModem, "transmit", CHANNEL_REPEAT, nReplyChannel, tMessage );
                sent = true
            end
        end
    end
end

function broadcast( message, sProtocol )
    send( CHANNEL_BROADCAST, message, sProtocol )
end