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annotate util/id.lua @ 12591:494577d883ff

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util.table: Fix inaccurate comment Probably a duplicate of the comment next to Lmove, recorded by mistake Lpack can probably be removed at some point in the near future once we are confident it is not used anywhere.
author Kim Alvefur <zash@zash.se>
date Mon, 11 Jul 2022 20:02:10 +0200
parents f8d280215633
children d10957394a3c
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9546c629289b util.id: New util for producing random identifiers of varying sizes
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1 -- Prosody IM
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2 -- Copyright (C) 2008-2017 Matthew Wild
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3 -- Copyright (C) 2008-2017 Waqas Hussain
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4 -- Copyright (C) 2008-2017 Kim Alvefur
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5 --
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6 -- This project is MIT/X11 licensed. Please see the
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7 -- COPYING file in the source package for more information.
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8 --
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9
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10 local s_gsub = string.gsub;
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11 local random_bytes = require "util.random".bytes;
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12 local base64_encode = require "util.encodings".base64.encode;
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13
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14 local b64url = { ["+"] = "-", ["/"] = "_", ["="] = "" };
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15 local function b64url_random(len)
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16 return (s_gsub(base64_encode(random_bytes(len)), "[+/=]", b64url));
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17 end
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18
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19 return {
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20 -- sizes divisible by 3 fit nicely into base64 without padding==
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21
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f8d280215633 util.id: Add a 'tiny' variant
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22 -- for short lived things with low risk of collisions
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23 tiny = function() return b64url_random(3); end;
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24
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25 -- close to 8 bytes, should be good enough for relatively short lived or uses
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26 -- scoped by host or users, half the size of an uuid
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27 short = function() return b64url_random(9); end;
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28
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29 -- more entropy than uuid at 2/3 the size
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30 -- should be okay for globally scoped ids or security token
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31 medium = function() return b64url_random(18); end;
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32
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33 -- as long as an uuid but MOAR entropy
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34 long = function() return b64url_random(27); end;
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35
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36 -- pick your own adventure
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37 custom = function (size)
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38 return function () return b64url_random(size); end;
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39 end;
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40 }