120 lines
4.0 KiB
Lua
120 lines
4.0 KiB
Lua
-- This file originates from this repository: https://github.com/iskolbin/lbase64
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-- It was modified to translate between base64 strings and lists of bytes instead of base64 strings and strings.
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local base64 = {}
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local extract = _G.bit32 and _G.bit32.extract -- Lua 5.2/Lua 5.3 in compatibility mode
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if not extract then
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if _G._VERSION == "Lua 5.4" then
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extract = load[[return function( v, from, width )
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return ( v >> from ) & ((1 << width) - 1)
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end]]()
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elseif _G.bit then -- LuaJIT
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local shl, shr, band = _G.bit.lshift, _G.bit.rshift, _G.bit.band
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extract = function( v, from, width )
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return band( shr( v, from ), shl( 1, width ) - 1 )
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end
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elseif _G._VERSION == "Lua 5.1" then
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extract = function( v, from, width )
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local w = 0
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local flag = 2^from
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for i = 0, width-1 do
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local flag2 = flag + flag
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if v % flag2 >= flag then
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w = w + 2^i
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end
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flag = flag2
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end
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return w
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end
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end
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end
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function base64.makeencoder( s62, s63, spad )
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local encoder = {}
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for b64code, char in pairs{[0]='A','B','C','D','E','F','G','H','I','J',
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'K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y',
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'Z','a','b','c','d','e','f','g','h','i','j','k','l','m','n',
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'o','p','q','r','s','t','u','v','w','x','y','z','0','1','2',
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'3','4','5','6','7','8','9',s62 or '+',s63 or'/',spad or'='} do
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encoder[b64code] = char:byte()
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end
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return encoder
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end
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function base64.makedecoder( s62, s63, spad )
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local decoder = {}
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for b64code, charcode in pairs( base64.makeencoder( s62, s63, spad )) do
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decoder[charcode] = b64code
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end
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return decoder
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end
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local DEFAULT_ENCODER = base64.makeencoder()
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local DEFAULT_DECODER = base64.makedecoder()
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local char, concat = string.char, table.concat
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function base64.encode( arr, encoder )
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encoder = encoder or DEFAULT_ENCODER
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local t, k, n = {}, 1, #arr
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local lastn = n % 3
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for i = 1, n-lastn, 3 do
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local a, b, c = arr[i], arr[i + 1], arr[i + 2]
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local v = a*0x10000 + b*0x100 + c
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local s
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s = char(encoder[extract(v,18,6)], encoder[extract(v,12,6)], encoder[extract(v,6,6)], encoder[extract(v,0,6)])
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t[k] = s
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k = k + 1
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end
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if lastn == 2 then
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local a, b = arr[n-1], arr[n]
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local v = a*0x10000 + b*0x100
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t[k] = char(encoder[extract(v,18,6)], encoder[extract(v,12,6)], encoder[extract(v,6,6)], encoder[64])
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elseif lastn == 1 then
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local v = arr[n]*0x10000
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t[k] = char(encoder[extract(v,18,6)], encoder[extract(v,12,6)], encoder[64], encoder[64])
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end
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return concat( t )
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end
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function base64.decode( b64, decoder )
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decoder = decoder or DEFAULT_DECODER
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local pattern = '[^%w%+%/%=]'
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if decoder then
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local s62, s63
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for charcode, b64code in pairs( decoder ) do
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if b64code == 62 then s62 = charcode
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elseif b64code == 63 then s63 = charcode
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end
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end
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pattern = ('[^%%w%%%s%%%s%%=]'):format( char(s62), char(s63) )
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end
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b64 = b64:gsub( pattern, '' )
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local t, k = {}, 1
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local n = #b64
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local padding = b64:sub(-2) == '==' and 2 or b64:sub(-1) == '=' and 1 or 0
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for i = 1, padding > 0 and n-4 or n, 4 do
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local a, b, c, d = b64:byte( i, i+3 )
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local s
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local v = decoder[a]*0x40000 + decoder[b]*0x1000 + decoder[c]*0x40 + decoder[d]
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table.insert(t,extract(v,16,8))
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table.insert(t,extract(v,8,8))
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table.insert(t,extract(v,0,8))
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end
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if padding == 1 then
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local a, b, c = b64:byte( n-3, n-1 )
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local v = decoder[a]*0x40000 + decoder[b]*0x1000 + decoder[c]*0x40
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table.insert(t,extract(v,16,8))
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table.insert(t,extract(v,8,8))
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elseif padding == 2 then
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local a, b = b64:byte( n-3, n-2 )
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local v = decoder[a]*0x40000 + decoder[b]*0x1000
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table.insert(t,extract(v,16,8))
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end
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return t
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end
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return base64
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