--------------------------------------------------------------------------------------- -- Copyright 2012 Rackspace (original), 2013 Thijs Schreijer (modifications) -- -- Licensed under the Apache License, Version 2.0 (the "License"); -- you may not use this file except in compliance with the License. -- You may obtain a copy of the License at -- -- http://www.apache.org/licenses/LICENSE-2.0 -- -- Unless required by applicable law or agreed to in writing, software -- distributed under the License is distributed on an "AS-IS" BASIS, -- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -- See the License for the specific language governing permissions and -- limitations under the License. -- -- see http://www.ietf.org/rfc/rfc4122.txt -- -- Note that this is not a true version 4 (random) UUID. Since `os.time()` precision is only 1 second, it would be hard -- to guarantee spacial uniqueness when two hosts generate a uuid after being seeded during the same second. This -- is solved by using the node field from a version 1 UUID. It represents the mac address. -- -- 28-apr-2013 modified by Thijs Schreijer from the original [Rackspace code](https://github.com/kans/zirgo/blob/807250b1af6725bad4776c931c89a784c1e34db2/util/uuid.lua) as a generic Lua module. -- Regarding the above mention on `os.time()`; the modifications use the `socket.gettime()` function from LuaSocket -- if available and hence reduce that problem (provided LuaSocket has been loaded before uuid). -- -- **6-nov-2015 Please take note of this issue**; [https://github.com/Mashape/kong/issues/478](https://github.com/Mashape/kong/issues/478) -- It demonstrates the problem of using time as a random seed. Specifically when used from multiple processes. -- So make sure to seed only once, application wide. And to not have multiple processes do that -- simultaneously (like nginx does for example). local M = {} local math = require('math') local os = require('os') local string = require('string') local bitsize = 32 -- bitsize assumed for Lua VM. See randomseed function below. local lua_version = tonumber(_VERSION:match("%d%.*%d*")) -- grab Lua version used local MATRIX_AND = {{0,0},{0,1} } local MATRIX_OR = {{0,1},{1,1}} local HEXES = '0123456789abcdef' local math_floor = math.floor local math_random = math.random local math_abs = math.abs local string_sub = string.sub local to_number = tonumber local assert = assert local type = type -- performs the bitwise operation specified by truth matrix on two numbers. local function BITWISE(x, y, matrix) local z = 0 local pow = 1 while x > 0 or y > 0 do z = z + (matrix[x%2+1][y%2+1] * pow) pow = pow * 2 x = math_floor(x/2) y = math_floor(y/2) end return z end local function INT2HEX(x) local s,base = '',16 local d while x > 0 do d = x % base + 1 x = math_floor(x/base) s = string_sub(HEXES, d, d)..s end while #s < 2 do s = "0" .. s end return s end ---------------------------------------------------------------------------- -- Creates a new uuid. Either provide a unique hex string, or make sure the -- random seed is properly set. The module table itself is a shortcut to this -- function, so `my_uuid = uuid.new()` equals `my_uuid = uuid()`. -- -- For proper use there are 3 options; -- -- 1. first require `luasocket`, then call `uuid.seed()`, and request a uuid using no -- parameter, eg. `my_uuid = uuid()` -- 2. use `uuid` without `luasocket`, set a random seed using `uuid.randomseed(some_good_seed)`, -- and request a uuid using no parameter, eg. `my_uuid = uuid()` -- 3. use `uuid` without `luasocket`, and request a uuid using an unique hex string, -- eg. `my_uuid = uuid(my_networkcard_macaddress)` -- -- @return a properly formatted uuid string -- @param hwaddr (optional) string containing a unique hex value (e.g.: `00:0c:29:69:41:c6`), to be used to compensate for the lesser `math_random()` function. Use a mac address for solid results. If omitted, a fully randomized uuid will be generated, but then you must ensure that the random seed is set properly! -- @usage -- local uuid = require("uuid") -- print("here's a new uuid: ",uuid()) function M.new(hwaddr) -- bytes are treated as 8bit unsigned bytes. local bytes = { math_random(0, 255), math_random(0, 255), math_random(0, 255), math_random(0, 255), math_random(0, 255), math_random(0, 255), math_random(0, 255), math_random(0, 255), math_random(0, 255), math_random(0, 255), math_random(0, 255), math_random(0, 255), math_random(0, 255), math_random(0, 255), math_random(0, 255), math_random(0, 255) } if hwaddr then assert(type(hwaddr)=="string", "Expected hex string, got "..type(hwaddr)) -- Cleanup provided string, assume mac address, so start from back and cleanup until we've got 12 characters local i,str = #hwaddr, hwaddr hwaddr = "" while i>0 and #hwaddr<12 do local c = str:sub(i,i):lower() if HEXES:find(c, 1, true) then -- valid HEX character, so append it hwaddr = c..hwaddr end i = i - 1 end assert(#hwaddr == 12, "Provided string did not contain at least 12 hex characters, retrieved '"..hwaddr.."' from '"..str.."'") -- no split() in lua. :( bytes[11] = to_number(hwaddr:sub(1, 2), 16) bytes[12] = to_number(hwaddr:sub(3, 4), 16) bytes[13] = to_number(hwaddr:sub(5, 6), 16) bytes[14] = to_number(hwaddr:sub(7, 8), 16) bytes[15] = to_number(hwaddr:sub(9, 10), 16) bytes[16] = to_number(hwaddr:sub(11, 12), 16) end -- set the version bytes[7] = BITWISE(bytes[7], 0x0f, MATRIX_AND) bytes[7] = BITWISE(bytes[7], 0x40, MATRIX_OR) -- set the variant bytes[9] = BITWISE(bytes[7], 0x3f, MATRIX_AND) bytes[9] = BITWISE(bytes[7], 0x80, MATRIX_OR) return INT2HEX(bytes[1])..INT2HEX(bytes[2])..INT2HEX(bytes[3])..INT2HEX(bytes[4]).."-".. INT2HEX(bytes[5])..INT2HEX(bytes[6]).."-".. INT2HEX(bytes[7])..INT2HEX(bytes[8]).."-".. INT2HEX(bytes[9])..INT2HEX(bytes[10]).."-".. INT2HEX(bytes[11])..INT2HEX(bytes[12])..INT2HEX(bytes[13])..INT2HEX(bytes[14])..INT2HEX(bytes[15])..INT2HEX(bytes[16]) end ---------------------------------------------------------------------------- -- Improved randomseed function. -- Lua 5.1 and 5.2 both truncate the seed given if it exceeds the integer -- range. If this happens, the seed will be 0 or 1 and all randomness will -- be gone (each application run will generate the same sequence of random -- numbers in that case). This improved version drops the most significant -- bits in those cases to get the seed within the proper range again. -- @param seed the random seed to set (integer from 0 - 2^32, negative values will be made positive) -- @return the (potentially modified) seed used -- @usage -- local socket = require("socket") -- gettime() has higher precision than os.time() -- local uuid = require("uuid") -- -- see also example at uuid.seed() -- uuid.randomseed(socket.gettime()*10000) -- print("here's a new uuid: ",uuid()) function M.randomseed(seed) seed = math_floor(math_abs(seed)) if seed >= (2^bitsize) then -- integer overflow, so reduce to prevent a bad seed seed = seed - math_floor(seed / 2^bitsize) * (2^bitsize) end if lua_version < 5.2 then -- 5.1 uses (incorrect) signed int math.randomseed(seed - 2^(bitsize-1)) else -- 5.2 uses (correct) unsigned int math.randomseed(seed) end return seed end ---------------------------------------------------------------------------- -- Seeds the random generator. -- It does so in 2 possible ways; -- -- 1. use `os.time()`: this only offers resolution to one second (used when -- LuaSocket hasn't been loaded yet -- 2. use luasocket `gettime()` function, but it only does so when LuaSocket -- has been required already. -- @usage -- local socket = require("socket") -- gettime() has higher precision than os.time() -- -- LuaSocket loaded, so below line does the same as the example from randomseed() -- uuid.seed() -- print("here's a new uuid: ",uuid()) function M.seed() if package.loaded["socket"] and package.loaded["socket"].gettime then return M.randomseed(package.loaded["socket"].gettime()*10000) else return M.randomseed(os.time()) end end return setmetatable( M, { __call = function(self, hwaddr) return self.new(hwaddr) end} )