VirtualFSLayer - NFS Server

-- VirtualFSLayer - NFS Server

-- NFS sync method:
-- Step1 / C->S: Request to connect
-- Step2 / S->C: Send challenge
-- Step3 / C->S: Send response
-- Step4 / S->C: Get SHA1 hash of all files on local store,
-- Client: Check which versions differ,
-- Step5 / C->S: transmit newer versions if necessary and list of files to get
-- Client: Write their versions of files to cache if necessary.
-- Step6 / S->C: transmit newer versions if necessary.

-- Authentication is Client->Server only

local args = {...}

if (not base64) and (not os.loadAPI("base64")) then
    if http then
        local h = http.get("http://pastebin.com/raw.php?i=pp3kpb19")
        if h then
            local data = h.readAll()
            h.close()
            local f = fs.open("base64", "w")
            f.write(data)
            f.close()
            if not os.loadAPI("base64") then
                error("Could not load base64 API!")
            end
        else
            error("Could not load base64 API!")
        end
    else
        error("Could not load base64 API!")
    end
end

if args[1] then
    print("Running with password authentication enabled.")
    if not (SHA2 or os.loadAPI("SHA2")) then
        error("Could not load SHA2 library!")
    end
else
    print("Running with password authentication disabled.")
end

if not (SHA1 or os.loadAPI("SHA1")) then
    if http then
        local h = http.get("http://pastebin.com/raw.php?i=QvtjCy9h")
        if h then
            local data = h.readAll()
            h.close()
            local f = fs.open("SHA1", "w")
            f.write(data)
            f.close()
            if not os.loadAPI("SHA1") then
                error("Could not load SHA1 API!")
            end
        else
            error("Could not load SHA1 API!")
        end
    else
        error("Could not load SHA1 API!")
    end
end

local filestorePath = "server/"
local NFSChannel = 0xDA7A
local NFSIdent = "NetFS"

local syncAttempts = {}
local basePW = {}

local fileHashCache = {} -- SHA1 hashes of all files in the cache
local fileTimestamps = {} -- Time
-- Timestamps are: {os.day(), os.time()}

if not fs.exists(filestorePath) then
    fs.makeDir(filestorePath)
end

if args[1] then
    for i=1, #args[1] do
        basePW[i] = string.byte(args[1], i, i)
    end
end

local modem = false

for i=1, 6 do
    local side = rs.getSides()[i]
    if peripheral.isPresent(side) and (peripheral.getType(side) == "modem") then
        print("Found modem on "..side)
        modem = peripheral.wrap(side)
        modem.open(NFSChannel)
        break
    end
end

local function updateCache()
    print("Updating hash cache...")
    function recursiveTraverse(dir)
        local listing = fs.list(dir)
        local dirs = {}
        local files = {}
        for i=1, #listing do
            if fs.isDir(listing[i]) then
                table.insert(dirs, listing[i])
                local f2, d2 = recursiveTraverse(fs.combine(dir, listing[i]))
                for i2=1, #f2 do
                    table.insert(files, f2[i])
                end
                for i2=1, #d2 do
                    table.insert(dirs, d2[i])
                end
            else
                table.insert(files, fs.combine(dir, listing[i]))
            end
        end
        return files, dirs
    end
    local cacheListing, dirListing = recursiveTraverse(filestorePath)
    for i=1, #cacheListing do
        local subPath = string.sub(cacheListing[i], #filestorePath)
        subPath = string.gsub(subPath, "\\", "/")
        if string.sub(subPath, 1, 1) == "/" then subPath = string.sub(subPath, 2) end
        if string.sub(subPath, #subPath, #subPath) == "/" then subPath = string.sub(subPath, 1, #subPath-1) end
        local f = fs.open(cacheListing[i], "rb")
        local d = {}
        local lastPause = os.clock()
        while true do
            local byte = f.read()
            if byte then
                table.insert(d, byte)
            else
                break
            end
            if (os.clock() - lastPause) >= 2.90 then
                os.queueEvent("")
                os.pullEvent("")
                lastPause = os.clock()
            end
        end
        f.close()
        local currentHash = SHA1.digest2str(SHA1.digest(d))
        if fileHashCache[subPath] ~= currentHash then
            fileTimestamps[subPath] = {os.day(), os.time()}
            fileHashCache[subPath] = currentHash
        end
        os.sleep(0)
    end
    print("Finished updating hash cache.")
end

if modem then
    updateCache()
    while true do
        local _, side, sCh, rCh, msg = os.pullEvent("modem_message")
        msg = textutils.unserialize(msg)
        if type(msg) == "table" then
            --print("Got message, ident is "..msg[1].." from "..msg[2].." addressed to "..msg[3])
            if (msg[1] == NFSIdent) and (msg[3] == os.computerID()) then
                local id = msg[2]
                if msg[4] == "Step1" then -- Auth request
                    print("Got auth request from "..id)
                    if args[1] then
                        if not syncAttempts[id] then
                            syncAttempts[id] = {{}, {}}
                            local cResponse = {}
                            for i=1, #basePW do
                                table.insert(cResponse, basePW[i])
                            end
                            for i=1, 16 do
                                syncAttempts[id][1][i] = math.random(0, 255)
                                table.insert(cResponse, syncAttempts[id][1][i])
                            end
                            --print("Sending step 2 to "..id)
                            modem.transmit(NFSChannel, NFSChannel, textutils.serialize({NFSIdent, os.computerID(), id, "Step2", syncAttempts[id][1]}))
                            syncAttempts[id][2] = SHA2.digest(cResponse)
                            --print("Sent step 2.")
                        end
                    else -- Skip to step4:
                        --print("Sending step 4 to "..id)
                        modem.transmit(NFSChannel, NFSChannel, textutils.serialize({NFSIdent, os.computerID(), id, "Step4", fileHashCache, fileTimestamps}))
                    end
                elseif msg[4] == "Step3" then -- Get response
                    print("Got auth response from "..id)
                    if syncAttempts[id][2] then
                        local response = msg[5]
                        local ok = true
                        for i=1, #msg[5] do
                            if response[i] ~= msg[5][i] then
                                ok = false
                                break
                            end
                        end
                        syncAttempts[id] = nil
                        if ok then
                            --print("Sending step 4 to "..id)
                            modem.transmit(NFSChannel, NFSChannel, textutils.serialize({NFSIdent, os.computerID(), id, "Step4", fileHashCache, fileTimestamps}))
                            --print("Sent step 4.")
                        else
                            --print("Sending auth failure to "..id)
                            modem.transmit(NFSChannel, NFSChannel, textutils.serialize({NFSIdent, os.computerID(), id, "AuthFailed"}))
                            --print("Sent auth failure.")
                        end
                    end
                elseif msg[4] == "Step5" then -- Get newer files / file list
                    print("Got changed file listing from "..id)
                    local fSendList = msg[6] -- Files to send to the client
                    local newFileList = msg[5] -- New versions of files
                    local fSendData = {} -- File data to send to client
                    local nSendList = 0
                    local nFileList = 0
                    for i,v in pairs(newFileList) do
                        nFileList = nFileList+1
                    end
                    for i,v in pairs(fSendList) do
                        nSendList = nSendList+1
                    end
                    print(nSendList.." files to send to client, ")
                    print(nFileList.." files to locally overwrite.")
                    for i,v in pairs(newFileList) do
                        local fullPath = fs.combine(filestorePath, i)
                        local fullBaseDir = string.sub(fullPath, 1, (#fullPath-#fs.getName(fullPath)))
                        if not fs.exists(fullBaseDir) then
                            fs.makeDir(fullBaseDir)
                        end
                        if string.sub(v, 1, 7) == "BINARY:" then
                            local data = base64.decode(string.sub(v, 8))
                            local lastPause = os.clock()
                            local f = fs.open(fullPath, "wb")
                            for i=1, #data do
                                f.write(data[i])
                                if (os.clock() - lastPause) >= 2.90 then
                                    os.queueEvent("")
                                    os.pullEvent("")
                                    lastPause = os.clock()
                                end
                            end
                            f.close()
                        else
                            local f = fs.open(fullPath, "w")
                            f.write(v)
                            f.close()
                        end
                    end
                    for i,v in pairs(fSendList) do
                        local f = fs.open(fs.combine(filestorePath, i), "rb")
                        local text = true
                        local lastPause = os.clock()
                        local data = {}
                        local dataStr = ""
                        while true do
                            local byte = f.read()
                            if byte then
                                if (byte < 0x20) or (byte > 0x7E) then
                                    text = false
                                end
                                table.insert(data, byte)
                                if text then
                                    dataStr = dataStr..string.char(byte)
                                end
                            else
                                break
                            end
                            if (os.clock() - lastPause) >= 2.90 then
                                os.queueEvent("")
                                os.pullEvent("")
                                lastPause = os.clock()
                            end
                        end
                        f.close()
                        if not text then
                            dataStr = "BINARY:"..base64.encode(data)
                        end
                        fSendData[i] = dataStr
                    end
                    --print("Sending step 6 to "..id)
                    modem.transmit(NFSChannel, NFSChannel, textutils.serialize({NFSIdent, os.computerID(), id, "Step6", fSendData}))
                    --print("Sent step 6.")
                    updateCache()
                end
            end
        end
    end
end