155 lines
3.1 KiB
Lua
155 lines
3.1 KiB
Lua
-- Base64 Encoder / Decoder
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-- By KillaVanilla
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-- see: http://www.computercraft.info/forums2/index.php?/topic/12450-killavanillas-various-apis/
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local Base64 = { }
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local bit = _G.bit
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local _brshift = bit.brshift
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local _bor = bit.bor
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local _blshift = bit.blshift
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local _band = bit.band
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local _sub = string.sub
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local os = _G.os
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local alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
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local function sixBitToBase64(input)
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return _sub(alphabet, input+1, input+1)
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end
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local function base64ToSixBit(input)
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for i=1, 64 do
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if input == _sub(alphabet, i, i) then
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return i-1
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end
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end
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end
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local function octetToBase64(o1, o2, o3)
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local i1 = sixBitToBase64(_brshift(_band(o1, 0xFC), 2))
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local i2
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local i3 = "="
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local i4 = "="
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if o2 then
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i2 = sixBitToBase64(_bor( _blshift(_band(o1, 3), 4), _brshift(_band(o2, 0xF0), 4) ))
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if not o3 then
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i3 = sixBitToBase64(_blshift(_band(o2, 0x0F), 2))
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else
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i3 = sixBitToBase64(_bor( _blshift(_band(o2, 0x0F), 2), _brshift(_band(o3, 0xC0), 6) ))
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end
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else
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i2 = sixBitToBase64(_blshift(_band(o1, 3), 4))
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end
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if o3 then
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i4 = sixBitToBase64(_band(o3, 0x3F))
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end
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return i1..i2..i3..i4
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end
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-- octet 1 needs characters 1/2
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-- octet 2 needs characters 2/3
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-- octet 3 needs characters 3/4
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local function base64ToThreeOctet(s1)
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local c1 = base64ToSixBit(_sub(s1, 1, 1))
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local c2 = base64ToSixBit(_sub(s1, 2, 2))
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local c3
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local c4
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local o1
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local o2
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local o3
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if _sub(s1, 3, 3) == "=" then
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c3 = nil
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c4 = nil
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elseif _sub(s1, 4, 4) == "=" then
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c3 = base64ToSixBit(_sub(s1, 3, 3))
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c4 = nil
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else
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c3 = base64ToSixBit(_sub(s1, 3, 3))
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c4 = base64ToSixBit(_sub(s1, 4, 4))
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end
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o1 = _bor( _blshift(c1, 2), _brshift(_band( c2, 0x30 ), 4) )
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if c3 then
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o2 = _bor( _blshift(_band(c2, 0x0F), 4), _brshift(_band( c3, 0x3C ), 2) )
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else
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o2 = nil
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end
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if c4 then
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o3 = _bor( _blshift(_band(c3, 3), 6), c4 )
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else
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o3 = nil
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end
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return o1, o2, o3
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end
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local function splitIntoBlocks(bytes)
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local blockNum = 1
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local blocks = {}
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for i=1, #bytes, 3 do
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blocks[blockNum] = {bytes[i], bytes[i+1], bytes[i+2]}
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--[[
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if #blocks[blockNum] < 3 then
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for j=#blocks[blockNum]+1, 3 do
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table.insert(blocks[blockNum], 0)
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end
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end
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]]
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blockNum = blockNum+1
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end
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return blocks
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end
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function Base64.encode(bytes)
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local blocks = splitIntoBlocks(bytes)
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local output = ""
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for i=1, #blocks do
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output = output..octetToBase64( unpack(blocks[i]) )
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end
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return output
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end
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local function Throttle()
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local ts = os.clock()
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local timeout = .095
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return function()
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local nts = os.clock()
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if nts > ts + timeout then
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os.sleep(0)
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ts = os.clock()
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end
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end
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end
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function Base64.decode(str)
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local bytes = {}
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local blocks = {}
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local blockNum = 1
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local throttle = Throttle()
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for i=1, #str, 4 do
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blocks[blockNum] = _sub(str, i, i+3)
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blockNum = blockNum+1
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end
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for i=1, #blocks do
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local o1, o2, o3 = base64ToThreeOctet(blocks[i])
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table.insert(bytes, o1)
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table.insert(bytes, o2)
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table.insert(bytes, o3)
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throttle()
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end
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-- Remove padding:
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--[[
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for i=#bytes, 1, -1 do
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if bytes[i] ~= 0 then
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break
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else
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bytes[i] = nil
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end
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end
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]]
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return bytes
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end
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return Base64
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