[CC/cardauth] auth_server

--[[
    Serveur d'authentification. Réagit aux requêtes réseau
    d'identification, crée des badges.
    Système de protection : hachage sha-256.

    Dépendances :
    - slot_sig
    - sha256
--]]

os.loadAPI('/lib/slot_sig')
os.loadAPI('/lib/sha256')

------------- PARAMETERS --------------
ID_READER_SIDE='left'
ID_MAKER_SIDE='right'
MODEM_SIDE='back'
MAINTENANCE_STR='MAINTENANCE'
------------- END PARAMS --------------

local hashDb = {}
local groupsDb = {}
local id_maker_auth = {} -- set of authorized IDs to create IDs.

os.pullEvent = os.pullEventRaw -- No return to terminal.

function rednetSend(to, message)
    rednet.send(to, message)
end

function authRequest(senderId, data, distance)
    if (hashDb[data.hash] ~= nil) then
        rednetSend(senderId, { type='authreply',
            user = hashDb[data.hash],
            groups = groupsDb[hashDb[data.hash]] })
    else
        rednetSend(senderId, {type = 'authreply'})
    end
end

function onRednet(input)
    ---EVENT: rednet_message
    senderId = input[1]
    if (type(input[2]) == 'string') then
        data = textutils.unserialize(input[2])

        if (data.reqtype == 'auth') then
            authRequest(senderId, data, distance)
        end
    end
end

----------- LOCAL ID FUNCTIONS -----------

function checkAuth()
    if not disk.hasData(ID_READER_SIDE) then
        return false
    end

    loc = '/'..disk.getMountPath(ID_READER_SIDE)..'/key'
    fileHandle = fs.open(loc,'r')
    if fileHandle == nil then
        return false
    end
    key = fileHandle.readLine()
    fileHandle.close()

    if key==MAINTENANCE_STR then
        slot_sig.quit()
    end

    keyHash = sha256.sha256(key)
    keyId = hashDb[keyHash]

    if keyId == nil or id_maker_auth[keyId] ~= true then
        return false
    end
    return true
end

function createKey()
    key = ""
    for i=1,2048 do
        key = key..string.char(math.random(33,126))
    end
    return key
end

function createID(idName, isMaster)
    if not(disk.isPresent(ID_MAKER_SIDE)) then
        printError("ID removed.")
    end
    disk.setLabel(ID_MAKER_SIDE, 'ID: '..idName)
    mountpath = disk.getMountPath(ID_MAKER_SIDE)
    keyHandle = fs.open(mountpath..'/key', 'w')

    key = createKey()
    hash = sha256.sha256(key)

    hashDb[hash] = idName
    if(isMaster) then
        id_maker_auth[idName] = true
    end

    groupSplit = {}
    for grp in groups:gmatch("%S+") do
        groupSplit[#groupSplit+1] = grp
    end
    groupsDb[idName] = groupSplit

    keyHandle.writeLine(key)
    keyHandle.close()
    disk.eject(ID_MAKER_SIDE)
end

function onDiskInsert(data)
    --- SIGNAL: disk
    side = data[1]
    if(side == ID_READER_SIDE) then
        isAuth = checkAuth()
        authorizedId(isAuth)
    elseif(side == ID_MAKER_SIDE) then
        if(checkAuth()) then
            -- Logged in, and creating a new card
            newId = getInput("Please type in the new ID:")
            isMaster = (getInput("Register as master ID (yes/no)?") == 'yes')
            groups = getInput("Groups the user belongs to (space separated:")
            createID(newId, isMaster, groups)
            disk.eject(ID_READER_SIDE)
            writeDB('/auth/hashdb',hashDb)
            writeDB('/auth/groupsdb',groupsDb)
            if(isMaster) then
                writeDB('/auth/idmakerdb',id_maker_auth)
            end
        else
            printError("Please insert your ID.")
            disk.eject(ID_MAKER_SIDE)
        end
    end
end

function onDiskRemoved(data)
    -- SIGNAL: disk_eject
    side = data[1]
    if(side == ID_READER_SIDE) then
        authorizedId(false)
        disk.eject(ID_MAKER_SIDE)
    end
end

----------- GUI FUNCTIONS ----------------

function serverRunning(isRunning)
    term.setCursorPos(1,1)
    if(isRunning) then
        term.setBackgroundColor(colors.lime)
        term.write("Server running")
    else
        term.setBackgroundColor(colors.red)
        term.write("Server offline")
    end
    term.setBackgroundColor(colors.black)
end

function authorizedId(isAuth)
    term.setCursorPos(16,1)
    if isAuth then
        term.setBackgroundColor(colors.lime)
        term.write("Logged in ")
    else
        term.setBackgroundColor(colors.red)
        term.write("Not logged")
    end
    term.setBackgroundColor(colors.black)
end

function clearLine(lineId)
    term.setCursorPos(1,lineId)
    term.clearLine()
end

function printError(str)
    term.setCursorPos(1,3)
    term.clearLine()
    term.setTextColor(colors.red)
    term.write(str)
    term.setTextColor(colors.black)
end

function getInput(prompt)
    term.setCursorPos(1,5)
    term.write(prompt.." ")
    out = read()
    term.setCursorPos(1,5)
    term.clearLine()
    return out
end

function mainscreen()
    term.clear()
    serverRunning(true)
    authorizedId(checkAuth())
end

-------- FS FUNCTIONS ----------------

function loadDB(path)
    handle = fs.open(path, 'r')
    if(handle == nil) then
        return {}
    end
    var = textutils.unserialize(handle.readAll())
    handle.close()

    if var == nil then
        return {}
    end
    return var
end

function writeDB(path,var)
    handle = fs.open(path,'w')
    if(handle == nil) then
        return
    end
    handle.write(textutils.serialize(var))
    handle.close()
end

-------- MAIN FUNCTION ---------------

function main()
    hashDb = loadDB('/auth/hashdb')
    id_maker_auth = loadDB('/auth/idmakerdb')
    groupsDb = loadDB('/auth/groupsdb')

    rednet.open(MODEM_SIDE)
    rednet.host("auth", "server")

    mainscreen()

    slot_sig.connectSlot('rednet_message', onRednet)
    slot_sig.connectSlot('disk', onDiskInsert)
    slot_sig.connectSlot('disk_eject', onDiskRemoved)
    slot_sig.run()
end
main()