118 lines
4.0 KiB
Lua
118 lines
4.0 KiB
Lua
local fullPath = shell.getRunningProgram()
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local dir = fullPath:match("^(.*/)") or ""
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local config = dofile(dir..'taskguard.cfg')
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local clearances = { } -- { computer_id = 1, clearance_level = 1, time_granted = os.clock() }
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local function split(str, divider)
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local t = {}
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for part in string.gmatch(str, "([^" .. divider .. "]+)") do
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table.insert(t, part)
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end
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return t
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end
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local function hash(str)
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local hash = 0
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for i = 1, #str do
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hash = (hash * 31 + string.byte(str, i)) % 65536
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end
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return string.format("%04X", hash)
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end
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local function check_for_outdated_sessions()
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local expired = 0
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for i = #clearances, 1, -1 do
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if (os.clock() - clearances[i].time_granted) > config.clearance_expiry then
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table.remove(clearances, i)
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expired = expired + 1
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end
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end
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print("Removed " .. expired .. " expired clearance(s). " ..
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#clearances .. " active session(s) remain.")
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end
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local function validate_key(card_holder, card_clearance, random_chars)
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local card_hash = hash(card_holder..','..card_clearance..','..random_chars)
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local key_file = fs.open(dir..config.key_file, 'r')
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local card_authentic = false
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while true do
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local trusted_hash = key_file.readLine()
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if trusted_hash == card_hash then
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print("Valid card "..card_hash)
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card_authentic = true
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return true, card_hash
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end
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if not line then break end -- Stop when EOF reached
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end
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key_file.close()
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if card_authentic == false then
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print("Unknown card "..card_hash)
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return false
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end
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end
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rednet.open(config.modem_side)
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rednet.host('tg', config.name)
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print("Server started, waiting for requests...")
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while true do
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local id, msg, proto = rednet.receive('tg')
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check_for_outdated_sessions()
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msg_parts = split(msg, ',')
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if msg_parts[1] == 'validate_clearance' then
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print("Beginning transaction for clearance query with "..id)
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local target_id = tonumber(msg_parts[2])
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local requested_clearance = tonumber(msg_parts[3])
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local has_clearance = false
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for i, entry in ipairs(clearances) do
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if entry.computer_id == target_id and entry.clearance_level >= requested_clearance then
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-- Auth granted
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rednet.send(id, 'granted', 'tg')
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print('Finished transaction, granted')
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has_clearance = true
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end
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end
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if has_clearance == false then
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-- Auth not granted
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rednet.send(id, 'failed', 'tg')
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print('Finished transaction, failed')
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end
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print("EOP")
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elseif msg_parts[1] == 'authenticate' then
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print("Beginning transaction for authentication with "..id)
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local card_holder = msg_parts[2]
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local card_clearance = msg_parts[3]
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local is_authentic, card_hash = validate_key(card_holder, card_clearance, msg_parts[4])
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if is_authentic then
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table.insert(clearances, { computer_id = tonumber(id), clearance_level = tonumber(card_clearance), time_granted = os.clock() })
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rednet.send(id, "authentication successful", "tg")
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print("Granted card "..card_hash.." clearance level "..card_clearance)
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else
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print("Unknown card "..card_hash)
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rednet.send(id, "authentication failed", "tg")
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end
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print("Transaction finished")
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elseif msg_parts[1] == 'validate_key' then
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print("Beginning transaction for single-validation with "..id)
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local card_holder = msg_parts[2]
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local card_clearance = msg_parts[3]
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local minimum_clearance = msg_parts[5]
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if validate_key(card_holder, card_clearance, msg_parts[4]) and tonumber(card_clearance) >= tonumber(minimum_clearance) then
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rednet.send(id, "authentication successful", "tg")
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else
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rednet.send(id, "authentication failed", "tg")
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end
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print("Transaction finished")
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end
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end |