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Diffstat (limited to 'nselib/base64.lua')
| -rw-r--r-- | nselib/base64.lua | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/nselib/base64.lua b/nselib/base64.lua new file mode 100644 index 0000000..478e29b --- /dev/null +++ b/nselib/base64.lua @@ -0,0 +1,203 @@ +-- The MIT License (MIT) +-- Copyright (c) 2016 Patrick Joseph Donnelly (batrick@batbytes.com) +-- +-- Permission is hereby granted, free of charge, to any person obtaining a copy of +-- this software and associated documentation files (the "Software"), to deal in +-- the Software without restriction, including without limitation the rights to +-- use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies +-- of the Software, and to permit persons to whom the Software is furnished to do +-- so, subject to the following conditions: +-- +-- The above copyright notice and this permission notice shall be included in all +-- copies or substantial portions of the Software. +-- +-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +-- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +-- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +-- SOFTWARE. + +--- +-- Base64 encoding and decoding. Follows RFC 4648. +-- +-- @author Patrick Donnelly <batrick@batbytes.com> +-- @copyright The MIT License (MIT); Copyright (c) 2016 Patrick Joseph Donnelly (batrick@batbytes.com) + +local assert = assert +local error = error +local ipairs = ipairs +local setmetatable = setmetatable + +local open = require "io".open +local popen = require "io".popen + +local random = require "math".random + +local tmpname = require "os".tmpname +local remove = require "os".remove + + +local char = require "string".char + +local concat = require "table".concat + +local unittest = require "unittest" + +_ENV = require "stdnse".module("base64") + +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', '+', '/' +} + +--- +-- Encodes a string to Base64. +-- @param p Data to be encoded. +-- @return Base64-encoded string. +function enc (p) + local out = {} + local i = 1 + local m = #p % 3 + + while i+2 <= #p do + local a, b, c = p:byte(i, i+2) + local e1 = b64table[((a>>2)&0x3f)+1]; + local e2 = b64table[((((a<<4)&0x30)|((b>>4)&0xf))&0x3f)+1]; + local e3 = b64table[((((b<<2)&0x3c)|((c>>6)&0x3))&0x3f)+1]; + local e4 = b64table[(c&0x3f)+1]; + out[#out+1] = e1..e2..e3..e4 + i = i + 3 + end + + if m == 2 then + local a, b = p:byte(i, i+1) + local c = 0 + local e1 = b64table[((a>>2)&0x3f)+1]; + local e2 = b64table[((((a<<4)&0x30)|((b>>4)&0xf))&0x3f)+1]; + local e3 = b64table[((((b<<2)&0x3c)|((c>>6)&0x3))&0x3f)+1]; + out[#out+1] = e1..e2..e3.."=" + elseif m == 1 then + local a = p:byte(i) + local b = 0 + local e1 = b64table[((a>>2)&0x3f)+1]; + local e2 = b64table[((((a<<4)&0x30)|((b>>4)&0xf))&0x3f)+1]; + out[#out+1] = e1..e2.."==" + end + + return concat(out) +end + +local db64table = setmetatable({}, {__index = function (t, k) error "invalid encoding: invalid character" end}) +do + local r = {["="] = 0} + for i, v in ipairs(b64table) do + r[v] = i-1 + end + for i = 0, 255 do + db64table[i] = r[char(i)] + end +end + +--- +-- Decodes Base64-encoded data. +-- @param e Base64 encoded data. +-- @return Decoded data. +function dec (e) + local out = {} + local i = 1 + local done = false + + e = e:gsub("%s+", "") + + local m = #e % 4 + if m ~= 0 then + error "invalid encoding: input is not divisible by 4" + end + + while i+3 <= #e do + if done then + error "invalid encoding: trailing characters" + end + + local a, b, c, d = e:byte(i, i+3) + + local x = ((db64table[a]<<2)&0xfc) | ((db64table[b]>>4)&0x03) + local y = ((db64table[b]<<4)&0xf0) | ((db64table[c]>>2)&0x0f) + local z = ((db64table[c]<<6)&0xc0) | ((db64table[d])&0x3f) + + if c == 0x3d then + assert(d == 0x3d, "invalid encoding: invalid character") + out[#out+1] = char(x) + done = true + elseif d == 0x3d then + out[#out+1] = char(x, y) + done = true + else + out[#out+1] = char(x, y, z) + end + i = i + 4 + end + + return concat(out) +end + +if not unittest.testing() then + return _ENV +end + +test_suite = unittest.TestSuite:new() + +local equal = unittest.equal +for i, test in ipairs({ + {"", ""}, + {"\x01", "AQ=="}, + {"\x00", "AA=="}, + {"\x00\x01", "AAE="}, + {"\x00\x01\x02", "AAEC"}, + {"\x00\x01\x02\x03", "AAECAw=="}, + {"\x00\x01\x02\x03\x04", "AAECAwQ="}, + {"\x00\x01\x02\x03\x04\x05", "AAECAwQF"}, + {"\x00\x01\x02\x03\x04\x05\x06", "AAECAwQFBg=="}, + {"\x00\x01\x02\x03\x04\x05\x06\x07", "AAECAwQFBgc="}, + }) do + test_suite:add_test(equal(enc(test[1]), test[2]), ("encoding string %d"):format(i)) + test_suite:add_test(equal(dec(test[2]), test[1]), ("decoding string %d"):format(i)) +end +for i = 1, 255 do + test_suite:add_test(equal(dec(enc(char(i))), char(i)), ("en/decoding char %d"):format(i)) +end + +-- whitespace stripping +test_suite:add_test(equal(dec(" AAEC A\r\nw=="), "\x00\x01\x02\x03"), "whitespace stripping") + +-- extensive tests +if false then + local path = tmpname() + local file = open(path, "w") + local t = {} + for a = 0, 255, random(1, 7) do + for b = 0, 255, random(2, 7) do + for c = 0, 255, random(2, 7) do + t[#t+1] = char(a, b, c, 0xA) + file:write(t[#t]) + end + end + end + assert(file:close()) + local input = concat(t) + local output = enc(input) + local good = assert(popen("base64 < "..path, "r")):read("a"):gsub("%s", "") + remove(path) + assert(output == good) + assert(dec(output) == input) +end + +return _ENV |