Add incomplete workspace, for now.

.gitignore

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+netref.dot
+netref.png

LICENSE

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+I, 20kdc, release this into the public domain.

culib.lua

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+-- 'Copper' networking test implementation.
+-- 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.
+
+-- Interfaces have no meaning, since addresses are names.
+-- Which "side" a system is on is irrelevant.
+-- 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.)
+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
+
+	-- Expect a response by this many seconds,
+	-- or else clear the known receivers cache and resend.
+	local tuningExpectResponse = 20
+
+	-- Flush the loop detector every so often.
+	-- This is not a complete clear.
+	local tuningFlushLoopDetector = 120
+
+	-- Do not change this value. I mean it. Don't. Just. Don't.
+	local tuningAutorejectLen = 4000
+
+	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
+
+	-- Unacknowledged packets.
+	-- Can cause an earlier cache flush.
+	-- [address] = giveupTime
+	-- (These are just forgotten after a while)
+	--local sentBNR = {}--NYI
+
+	-- [address] = {
+	--      node,
+	--      expiry
+	-- }
+	--local lastKnownReceiver = {}--NYI
+
+	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 = time() + tuningFlushLoopDetector
+		end
+	end
+
+	local culib = {}
+
+	-- Can be changed.
+	culib.hostname = hostname
+	culib.input = function (node, message)
+		if message:len() > tuningAutorejectLen then
+			return
+		end
+		if seenBefore[message] then
+			seenBefore[message] = seenBefore[message] + 1
+			return
+		else
+			seenBefore[message] = 0
+			seenBeforeCount = seenBeforeCount + 1
+			if seenBeforeCount > tuningMaxSeenBeforeCountBeforeEmergencyFlush then
+				-- Panic
+				seenBeforeCount = 0
+				seenBefore = {}
+			end
+		end
+		if message:len() < 2 then return end
+		local nlen = message:byte(1) + 1
+		local fnam = message:sub(1, nlen)
+		message = message:sub(nlen + 1)
+		if message:len() < 2 then return end
+		local nlen = message:byte(1) + 1
+		local tnam = message:sub(1, nlen)
+		message = message:sub(nlen + 1)
+		if message:len() < 1 then return end
+		onReceive(fnam, tnam, message)
+		if culib.hostname == tnam then return end
+		-- Redistribution of messages not aimed here
+		transmit(nil, message)
+	end
+	culib.output = function (fnam, tnam, message)
+		onReceive(fnam, tnam, message)
+		if tnam == culib.hostname then return end
+		transmit(nil, encodeName(fnam) .. encodeName(tnam) .. message)
+	end
+	return culib
+end

gennet.lua

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+-- Generate connected network where all nodes are connected.
+-- Saves graph to "netref.dot", outputs lua tables to stdout.
+
+local nodes = {}
+local wordsA = {
+	"changing",
+	"ponderous",
+	"intriguing",
+	"bright",
+	"solitudial",
+	"nuanced"
+}
+local wordsB = {
+	"fontaine",
+	"marple",
+	"poirot",
+	"pinkie",
+	"sparks",
+	"twi"
+}
+for i = 1, #wordsA do
+	for j = 1, #wordsB do
+		table.insert(nodes, wordsA[i] .. "_" .. wordsB[j])
+	end
+end
+
+local connections = {}
+for i = 1, #nodes do
+	connections[i] = {}
+	connections[i][i] = true
+end
+
+-- Recursive algorithm.
+-- It will always come to the right answer, though.
+-- (But definitely wouldn't ever return the fastest route.)
+local function canRoute(i, j, avoid)
+	if i == j then return true end
+	if avoid[i] then return false end
+	avoid[i] = true
+	for p = 1, #nodes do
+		if connections[i][p] then
+			if canRoute(p, j, avoid) then
+				return true
+			end
+		end
+	end
+	return false
+end
+
+local function ensureRoute(i, j)
+	while not canRoute(i, j, {}) do
+		local a, b = math.random(#nodes), math.random(#nodes)
+		connections[a][b] = true
+		connections[b][a] = true
+	end
+end
+
+print("return function (declare, connect)")
+for i = 1, #nodes do
+	-- Perform declaration here so next pass can do connections
+	print(" declare(\"" .. nodes[i] .. "\")")
+	for j = i + 1, #nodes do
+		ensureRoute(i, j)
+	end
+end
+
+local dot = io.open("netref.dot", "w")
+dot:write("graph \"Test Network Reference Graph\" {\n")
+-- Notably this is a destructive process (to prevent backwards links)
+for i = 1, #nodes do
+	for p = 1, #nodes do
+		if (p ~= i) and connections[i][p] then
+			print(" connect(" .. i .. ", " .. p .. ")")
+			dot:write(" " .. nodes[i] .. " -- " .. nodes[p] .. ";\n")
+			connections[p][i] = false
+		end
+	end
+end
+dot:write("}")
+dot:close()
+print("end")

protocol.0

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+Copper Protocol
+ 20kdc, 2017
+
+Copper is a simple to implement networking protocol based on names.
+This is it's sole purpose.
+It can be used in various contexts, though it is not suitable as a 
+ secure peer-to-peer networking protocol where all actors are untrusted.
+
+Rather, Copper is better for the situation of the current internet -
+ hierarchial structures (operated by semi-trusted parties, with 
+ encryption used to hide information from them as appropriate),
+ with arbitary network structure at the fully-trusted-network level.
+
+Copper addresses are names.
+In the context of a system not implementing a hierarchial gateway,
+ this is as much about Copper addressing as matters.
+
+Copper base packets contain 3 fields.
+A name (as a length-minus-1-byte-prefixed-string),
+ another name (in the same format),
+ and the rest is data.
+
+Copper packets may be up to 4000 bytes long, including base.
+(It's assumed the additional 96 bytes will be useful for any additional 
+ framing, assuming a 4K packet limit.)
+
+Loop detection should performed by checking if a packet exactly the same has 
+ been seen recently - other rejection, alteration and routing measures 
+ are up to the implementer.
+
+Signalling is inadvisable - Copper is primarily meant to allow creating 
+ internally "partyline" OpenComputers in-game networks with named nodes
+ and some semblance of routing or structure.
+
+Should a situation be dire enough,
+ hierarchial networks (described in file 2, 'protocol.1'),
+ and custom routing software in general,
+ can be used to split networks however the system requires.
+Copper isn't very picky.

protocol.1

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+Copper Protocol :: Hierarchial Gateways
+ 20kdc, 2017
+
+"Hierarchial Gateways" are a system for ISP-like bodies to prevent their
+ users from causing havoc.
+They are simply base low-level Copper nodes with two interfaces and the
+ following rules:
+
+ For the FROM address:
+
+If it's on the parent side, reject if it's prefixed with hostname .. 
+"/",
+ otherwise prefix it with "<" and forward to child side.
+If it's on the child side, reject if it's prefixed with "<",
+ otherwise prefix it with hostname .. "/" and forward to parent side.
+
+ For the TO address:
+
+If it's on the parent side, reject unless prefixed with hostname .. "/",
+ otherwise remove that and forward to child side.
+If it's on the child side, reject unless prefixed with "<",
+ otherwise remove that and forward to parent side.
+
+This introduces a simple hierarchial structure that does not require any
+ support code apart from in the nodes supporting the hierarchy.
+There are only two downsides:
+ 1. Nodes connected to two gateways
+     could have multiple addresses but believe they only have one
+ 2. Nodes behind two nested gateways can address themselves in two ways
+
+However, this should all work out as long as people make a deliberate
+ effort not to notice the hierarchial structure system in their code.
+
+Specifically, problem 2 only causes an issue should some nodes not
+ directly involved in gateway activities be
+ attempting to parse hierarchial addresses.
+
+Possible uses of hierarchial gateways:
+1. A safe (untrusting of servers in it) inter-server networking hub,
+    following the same protocol as everything else in Copper,
+    unlike certain competitors
+2. ISPs within servers, perhaps those using the hubs

protocol.2

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+Copper Protocol :: Reliability/Fragmentation Layer
+ 20kdc, 2017
+
+The Copper Protocol as described in files 1 and 2 does not have any 
+ semblance of application multiplexing or failure recovery.
+
+This is intentional.
+Assuming that nobody is trying to make the fatal mistake of constructing 
+ a NAT, files 1 and 2 are enough for all routing-related purposes.
+
+For applications, however, a protocol must be layered on top.
+
+This document on the Reliability Layer describes how that should work.
+
+
+All implementations of Copper that synthesize their own packets SHOULD 
+ follow this protocol when doing so, unless they are a custom system 
+ that will not be connected to any global network.
+
+
+Firstly, note that, to the application, a Reliability Layer packet can 
+ be up to 59,895 bytes in size, though a fragment can only be up to 3993 bytes.
+
+Secondly, note that an application should be able to ask to be notified 
+ when a packet is received successfully or when the implementation gives up,
+ with a flag indicating which is which.
+
+Reliability Layer packets have a simple format.
+The first two bytes are the port number, in big-endian format.
+The next three bytes are a number to this application-side packet.
+They should be as random as possible.
+The next byte is the 'attempt number' - the amount of attempts by this 
+ side of the Reliability Layer "connection" to send a packet with this 
+ meaning.
+
+This can be achieved serially or otherwise, but should have a random base.
+Combined with correctly-forgetting packet caches, this should prevent 
+ any packets lost by data collision.
+The final header byte is the actual indicator of what is in the packet.
+
+The upper nibble indicates the amount of fragments in the packet - 0 
+ indicates an acknowledgement.
+The lower nibble indicates which fragment this is, or if this is an 
+ acknowledgement, which fragment was acknowledged.
+
+0x0F indicates that this is a *deliberately* unreliable packet.
+(These packets cannot be fragmented or acknowledged, and thus have the 
+  per-fragment limit of 3993 bytes.
+ The attempt number and primary packet number still have meaning.)
+
+Two example scenarioes will now be presented:
+
+1.
+
+ARCHWAYS sends a 0x10 'First fragment of a one fragment packet' to 
+ IWAKURA on port 8080, twice (the first attempt being dropped).
+ 1F 90 | F4 21 B9 | 00/01    | 10 | (...)
+ port    packetID   Attempt    CC   Data
+
+IWAKURA receives it successfully on the second time, and sends back a 
+ response, three times.
+ 1F 90 | F4 21 B9 | 00/01/02 | 00
+ port    packetID   Attempt    CC
+
+ARCHWAYS receives the response and does not send a third packet.
+
+2.
+
+IWAKURA, having parsed the packet, sends back a long response on the same port.
+The response is two packets long.
+ 1F 90 | 91 19 28 | 00 | 20 | (...)
+ 1F 90 | 91 19 28 | 00 | 21 | (...)
+
+ARCHWAYS receives both packets, in the wrong order
+ (but it reassembles it anyway), and ACKs three times...
+ ...but the packets are dropped due to a crow getting in the way of the 
+ satellite dish at the wrong point. Blasted crow.
+
+ 1F 90 | 91 19 28 | 00/01/02 | 21
+ 1F 90 | 91 19 28 | 00/01/02 | 20
+
+IWAKURA, waiting, say, 6 seconds
+ (assuming ACKs are sent a second and a half apart) sends a retransmission.
+
+ 1F 90 | 91 19 28 | 01 | 20 | (...)
+ 1F 90 | 91 19 28 | 01 | 21 | (...)
+
+ARCHWAYS ACKs the retransmission, just in case - this works.
+
+ 1F 90 | 91 19 28 | 00/01/02 | 21
+ 1F 90 | 91 19 28 | 00/01/02 | 20
+
+IWAKURA's application knows the message got through.

runtest.lua

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+-- Load testnet
+local nodes = {}
+local nodenames = {}
+loadfile("testnet.lua")(function (n)
+	table.insert(nodes, {})
+	table.insert(nodenames, n)
+end, function (a, b)
+	table.insert(nodes[a], b)
+	table.insert(nodes[b], a)
+end)
+
+-- Start testing
+require("culib")

testnet.lua

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+return function (declare, connect)
+ declare("changing_fontaine")
+ declare("changing_marple")
+ declare("changing_poirot")
+ declare("changing_pinkie")
+ declare("changing_sparks")
+ declare("changing_twi")
+ declare("ponderous_fontaine")
+ declare("ponderous_marple")
+ declare("ponderous_poirot")
+ declare("ponderous_pinkie")
+ declare("ponderous_sparks")
+ declare("ponderous_twi")
+ declare("intriguing_fontaine")
+ declare("intriguing_marple")
+ declare("intriguing_poirot")
+ declare("intriguing_pinkie")
+ declare("intriguing_sparks")
+ declare("intriguing_twi")
+ declare("bright_fontaine")
+ declare("bright_marple")
+ declare("bright_poirot")
+ declare("bright_pinkie")
+ declare("bright_sparks")
+ declare("bright_twi")
+ declare("solitudial_fontaine")
+ declare("solitudial_marple")
+ declare("solitudial_poirot")
+ declare("solitudial_pinkie")
+ declare("solitudial_sparks")
+ declare("solitudial_twi")
+ declare("nuanced_fontaine")
+ declare("nuanced_marple")
+ declare("nuanced_poirot")
+ declare("nuanced_pinkie")
+ declare("nuanced_sparks")
+ declare("nuanced_twi")
+ connect(1, 3)
+ connect(1, 9)
+ connect(2, 20)
+ connect(3, 17)
+ connect(3, 35)
+ connect(4, 5)
+ connect(4, 19)
+ connect(5, 29)
+ connect(6, 15)
+ connect(6, 22)
+ connect(6, 25)
+ connect(6, 32)
+ connect(7, 10)
+ connect(7, 24)
+ connect(8, 18)
+ connect(8, 33)
+ connect(8, 36)
+ connect(9, 17)
+ connect(9, 33)
+ connect(9, 35)
+ connect(10, 20)
+ connect(11, 13)
+ connect(11, 23)
+ connect(11, 27)
+ connect(11, 28)
+ connect(12, 29)
+ connect(12, 30)
+ connect(13, 24)
+ connect(13, 25)
+ connect(13, 28)
+ connect(13, 33)
+ connect(14, 19)
+ connect(14, 28)
+ connect(15, 21)
+ connect(15, 30)
+ connect(15, 31)
+ connect(15, 33)
+ connect(16, 24)
+ connect(16, 32)
+ connect(16, 34)
+ connect(18, 23)
+ connect(18, 36)
+ connect(19, 23)
+ connect(19, 25)
+ connect(19, 28)
+ connect(19, 31)
+ connect(22, 35)
+ connect(23, 26)
+ connect(24, 31)
+ connect(25, 33)
+ connect(26, 34)
+ connect(30, 34)
+ connect(31, 33)
+ connect(33, 35)
+ connect(34, 35)
+end