From a37dfa7f3ee4944c89f389f21c68cb6aa4e2ed16 Mon Sep 17 00:00:00 2001
From: pgpickering <pgpickering@e0a8ed71-7df4-0310-8962-fdc924857419>
Date: Thu, 31 Jul 2008 22:49:39 +0000
Subject: [PATCH] added base64.lua

---
 nselib/base64.lua | 160 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 160 insertions(+)
 create mode 100644 nselib/base64.lua

diff --git a/nselib/base64.lua b/nselib/base64.lua
new file mode 100644
index 000000000..f42863d49
--- /dev/null
+++ b/nselib/base64.lua
@@ -0,0 +1,160 @@
+--- Base64 library
+--@copyright See nmaps COPYING for licence
+
+-- as in RFC4648
+-- author: Philip Pickering <pgpickering@gmail.com>
+-- thanks to Patrick Donnelly for some optimizations
+
+module(...,package.seeall)
+
+
+-- todo: make metatable/index --> '' for b64dctable
+
+
+local b64table = {
+	'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
+	'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
+	'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
+	'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
+	'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
+	'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
+	'w', 'x', 'y', 'z', '0', '1', '2', '3', 
+	'4', '5', '6', '7', '8', '9', '+', '/'
+	}
+	
+local b64dctable = {} -- efficency
+b64dctable['A'] = '000000'
+b64dctable['B'] = '000001'
+b64dctable['C'] = '000010'
+b64dctable['D'] = '000011'
+b64dctable['E'] = '000100'
+b64dctable['F'] = '000101'
+b64dctable['G'] = '000110'
+b64dctable['H'] = '000111'
+b64dctable['I'] = '001000'
+b64dctable['J'] = '001001'
+b64dctable['K'] = '001010'
+b64dctable['L'] = '001011'
+b64dctable['M'] = '001100'
+b64dctable['N'] = '001101'
+b64dctable['O'] = '001110'
+b64dctable['P'] = '001111'
+b64dctable['Q'] = '010000'
+b64dctable['R'] = '010001'
+b64dctable['S'] = '010010'
+b64dctable['T'] = '010011'
+b64dctable['U'] = '010100'
+b64dctable['V'] = '010101'
+b64dctable['W'] = '010110'
+b64dctable['X'] = '010111'
+b64dctable['Y'] = '011000'
+b64dctable['Z'] = '011001'
+b64dctable['a'] = '011010'
+b64dctable['b'] = '011011'
+b64dctable['c'] = '011100'
+b64dctable['d'] = '011101'
+b64dctable['e'] = '011110'
+b64dctable['f'] = '011111'
+b64dctable['g'] = '100000'
+b64dctable['h'] = '100001'
+b64dctable['i'] = '100010'
+b64dctable['j'] = '100011'
+b64dctable['k'] = '100100'
+b64dctable['l'] = '100101'
+b64dctable['m'] = '100110'
+b64dctable['n'] = '100111'
+b64dctable['o'] = '101000'
+b64dctable['p'] = '101001'
+b64dctable['q'] = '101010'
+b64dctable['r'] = '101011'
+b64dctable['s'] = '101100'
+b64dctable['t'] = '101101'
+b64dctable['u'] = '101110'
+b64dctable['v'] = '101111'
+b64dctable['w'] = '110000'
+b64dctable['x'] = '110001'
+b64dctable['y'] = '110010'
+b64dctable['z'] = '110011'
+b64dctable['0'] = '110100'
+b64dctable['1'] = '110101'
+b64dctable['2'] = '110110'
+b64dctable['3'] = '110111'
+b64dctable['4'] = '111000'
+b64dctable['5'] = '111001'
+b64dctable['6'] = '111010'
+b64dctable['7'] = '111011'
+b64dctable['8'] = '111100'
+b64dctable['9'] = '111101'
+b64dctable['+'] = '111110'
+b64dctable['/'] = '111111'
+
+
+local append = table.insert
+local substr = string.sub
+local bpack = bin.pack 
+local bunpack = bin.unpack
+local concat = table.concat
+
+
+local function b64enc6bit(bits)
+	-- local byte
+	-- local _, byte = bunpack("C", bpack("B", "00" .. bits))
+	--
+	
+	-- more efficient, does the same (nb: add one to byte moved up one line):
+	local byte = tonumber(bits, 2) + 1
+	return b64table[byte]
+end
+
+local function b64dec6bit(b64byte)
+	local bits = b64dctable[b64byte]
+	if bits then return bits end
+	return ''
+end
+
+function enc(bdata)
+	local pos = 1
+	local byte
+	local nbyte = ''
+	-- local nbuffer = {}
+	local b64dataBuf = {}
+	while pos <= #bdata  do
+		pos, byte = bunpack("B1", bdata, pos)
+		nbyte = nbyte .. byte
+		append(b64dataBuf, b64enc6bit(substr(nbyte, 1, 6)))
+		nbyte = substr(nbyte,7)
+		if (#nbyte == 6) then
+			append(b64dataBuf, b64enc6bit(nbyte))
+			nbyte = ''
+		end
+	end
+	if #nbyte == 2 then
+		append(b64dataBuf, b64enc6bit(nbyte)) 
+			-- relying on pack's 0-autopadding
+		append(b64dataBuf, "==")
+	elseif #nbyte == 4 then
+		append(b64dataBuf, b64enc6bit(nbyte))
+			-- relying on pack's 0-autopadding
+		append(b64dataBuf, '=')
+	end
+	return concat(b64dataBuf)
+end
+
+function dec(b64data)
+	local bdataBuf = {}
+	local pos = 1
+	local byte
+	local nbyte = ''
+	for pos = 1, #b64data do -- while pos <= string.len(b64data) do
+		byte = b64dec6bit(substr(b64data, pos, pos))
+		if not byte then return end
+		nbyte = nbyte .. byte
+		if #nbyte >= 8 then
+			append(bdataBuf, bpack("B", substr(nbyte, 1, 8)))
+			nbyte = substr(nbyte, 9)
+		end
+--		pos = pos + 1
+	end
+	return concat(bdataBuf)
+end
+