-- I, 20kdc, release this into the public domain. -- No warranty is provided, implied or otherwise. -- 'Copper' networking - "The Routing Library". -- This is meant as a portable (even into OC) library for networking. -- This 'outer function' is the instantiator. -- Note that it is probably possible to cause this code to run out of -- memory in several hilarious ways. -- I've taken the approach that reduction of code . -- Interfaces have no meaning, since addresses are names. -- Which "side" a system is on is irrelevant. -- (Unless you're developing a hierarchial gateway, in which case this library isn't for you -- as it follows a default set of routing rules. Switch to cdlib for fine-grained control.) -- For sending, the following function is used: -- transmit(nodeId, message) -- The nodeId is a string or number that has been given via culib.input, -- or nil for broadcast. -- It's more of a suggestion than a requirement to check nodeId. -- The message is always a string. -- This mirrors the message format usable by sendPacket and onReceive. -- "onReceive" is a function which is called when a packet is decoded. -- onReceive(namefrom, nameto, data) -- "time" is a function which returns the real time, in seconds. -- It need not be precise. -- (This is used for caches.) local cdlib = require("cdlib") return function (hostname, transmit, onReceive, time) -- How many packets need to be stored in seenBefore's keyspace -- before 'panic' is the best response? local tuningMaxSeenBeforeCountBeforeEmergencyFlush = 0x100 -- Prevents OOM by LKR cache flooding - how many entries can the LKR have, max? -- (Though spamming packets from many sources is now a viable method for dropping LKR, -- it used to be a viable OOM method.) -- Note that setting this to 0 or less will effectively result in a value of 1. local tuningMaxLKREntries = 0x200 -- Expect another packet after this amount of time, -- or else clear the known receivers cache entry. -- Minimum should be less or equal to tuningAttempts * -- tuningAttemptTime in relib. local tuningExpectContinue = 15 + math.random(15) -- Flush the loop detector every so often. -- This is not a complete clear. local tuningFlushLoopDetector = 60 -- Do not change this value unless protocol has changed accordingly. local tuningAutorejectLen = 1507 local loopDetectorNext = time() + tuningFlushLoopDetector -- Packets that have been seen before. -- The values are the amount of times a packet has been seen. -- This is flushed every tuningFlushLoopDetector seconds - -- the flushing decrements the value until it reaches 0, -- so packets which have looped before get a longer timeout. local seenBefore = {} local seenBeforeCount = 0 -- [address] = { -- node, -- the node that a message was received from -- expiry -- } local lastKnownReceiver = {} -- How many LKR entries are there? local lkrCacheCount = 0 local function refresh() local t = time() if t >= loopDetectorNext then for k, v in pairs(seenBefore) do local n = v - 1 if n > 0 then seenBefore[k] = n else seenBefore[k] = nil seenBeforeCount = seenBeforeCount - 1 end end loopDetectorNext = t + tuningFlushLoopDetector end for k, v in pairs(lastKnownReceiver) do if t >= v[2] then --print("It was decided LKV[" .. k .. "] was out of date @ " .. v[2] .. " by " .. hostname) lastKnownReceiver[k] = nil end end end -- Used to clean up LKR entries to prevent OOM. local function removeOldestLKR() local lowest = nil local lowestExpiry = math.huge for k, v in pairs(lastKnownReceiver) do if v[2] < lowestExpiry then lowest = k end end if lowest then lastKnownReceiver[lowest] = nil lkrCacheCount = lkrCacheCount - 1 end end local culib = {} -- Can be changed. culib.hostname = hostname -- Stats. culib.lkrCacheMisses = 0 culib.lkrCacheHits = 0 culib.input = function (node, message) local t = time() -- Eliminate the hops value first of all. local hops = message:byte(1) message = message:sub(2) if seenBefore[message] then seenBefore[message] = seenBefore[message] + 1 return else seenBefore[message] = 2 seenBeforeCount = seenBeforeCount + 1 if seenBeforeCount > tuningMaxSeenBeforeCountBeforeEmergencyFlush then -- Panic seenBeforeCount = 0 seenBefore = {} end end -- Begin parsing. local fnam, tnam, data = cdlib.decodeNoHops(message) if not data then return end if data:len() > tuningAutorejectLen then return end if fnam ~= "*" then if not lastKnownReceiver[fnam] then -- if, not while, because if someone ignores my note above -- and sets the tuning to 0 it would crash otherwise. *sigh* if lkrCacheCount >= tuningMaxLKREntries then removeOldestLKR() end lkrCacheCount = lkrCacheCount + 1 end lastKnownReceiver[fnam] = {node, t + tuningExpectContinue} end onReceive(fnam, tnam, data) if culib.hostname == tnam then return end -- Redistribution of messages not aimed here if hops == 255 then -- Don't redistribute return else -- Prepend the hops byte that got removed earlier message = string.char(hops + 1) .. message end local lkr = lastKnownReceiver[tnam] if lkr then culib.lkrCacheHits = culib.lkrCacheHits + 1 transmit(lkr[1], message) else culib.lkrCacheMisses = culib.lkrCacheMisses + 1 transmit(nil, message) end end culib.refresh = refresh culib.output = function (fnam, tnam, message) if message:len() > tuningAutorejectLen then error("Attempted to send too long packet") end onReceive(fnam, tnam, message) if tnam == culib.hostname then return end local m = cdlib.encode(0, fnam, tnam, message) transmit(nil, m) end return culib end