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#
# Unpacker for Dean Edward's p.a.c.k.e.r, a part of javascript beautifier
# by Einar Lielmanis <einar@jsbeautifier.org>
#
# written by Stefano Sanfilippo <a.little.coder@gmail.com>
#
# usage:
#
# if detect(some_string):
# unpacked = unpack(some_string)
#
"""Unpacker for Dean Edward's p.a.c.k.e.r"""
import re
from . import UnpackingError
PRIORITY = 1
def detect(source):
"""Detects whether `source` is P.A.C.K.E.R. coded."""
return source.replace(' ', '').startswith('eval(function(p,a,c,k,e,r')
def unpack(source):
"""Unpacks P.A.C.K.E.R. packed js code."""
payload, symtab, radix, count = _filterargs(source)
if count != len(symtab):
raise UnpackingError('Malformed p.a.c.k.e.r. symtab.')
try:
unbase = Unbaser(radix)
except TypeError:
raise UnpackingError('Unknown p.a.c.k.e.r. encoding.')
def lookup(match):
"""Look up symbols in the synthetic symtab."""
word = match.group(0)
return symtab[unbase(word)] or word
source = re.sub(r'\b\w+\b', lookup, payload)
return _replacestrings(source)
def _filterargs(source):
"""Juice from a source file the four args needed by decoder."""
argsregex = (r"}\('(.*)', *(\d+), *(\d+), *'(.*)'\."
r"split\('\|'\), *(\d+), *(.*)\)\)")
args = re.search(argsregex, source, re.DOTALL).groups()
try:
return args[0], args[3].split('|'), int(args[1]), int(args[2])
except ValueError:
raise UnpackingError('Corrupted p.a.c.k.e.r. data.')
def _replacestrings(source):
"""Strip string lookup table (list) and replace values in source."""
match = re.search(r'var *(_\w+)\=\["(.*?)"\];', source, re.DOTALL)
if match:
varname, strings = match.groups()
startpoint = len(match.group(0))
lookup = strings.split('","')
variable = '%s[%%d]' % varname
for index, value in enumerate(lookup):
source = source.replace(variable % index, '"%s"' % value)
return source[startpoint:]
return source
class Unbaser(object):
"""Functor for a given base. Will efficiently convert
strings to natural numbers."""
ALPHABET = {
62 : '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ',
95 : (' !"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ'
'[\]^_`abcdefghijklmnopqrstuvwxyz{|}~')
}
def __init__(self, base):
self.base = base
# If base can be handled by int() builtin, let it do it for us
if 2 <= base <= 36:
self.unbase = lambda string: int(string, base)
else:
# Build conversion dictionary cache
try:
self.dictionary = dict((cipher, index) for
index, cipher in enumerate(self.ALPHABET[base]))
except KeyError:
raise TypeError('Unsupported base encoding.')
self.unbase = self._dictunbaser
def __call__(self, string):
return self.unbase(string)
def _dictunbaser(self, string):
"""Decodes a value to an integer."""
ret = 0
for index, cipher in enumerate(string[::-1]):
ret += (self.base ** index) * self.dictionary[cipher]
return ret
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