forked from thuxnder/dalvik-obfuscator
/
DexFileParser.py
349 lines (282 loc) · 14.5 KB
/
DexFileParser.py
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#!/usr/bin/env python
#
# Copyright (C) 2012 thuxnder@dexlabs.org
#
# Licensed under the Apache License, Version 2.0 (the 'License');
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an 'AS IS' BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
import sys
import struct
import zlib
import array
class ObjResolver:
def __init__(self, dexfile):
self._dex = dexfile
#TODO mutf8 translation
def getStringByIdx(self, idx):
return self._dex.stringdataitems[ self._dex.stringiditems[idx]['string_data_off'] ]['data']
def getClassByIdx(self, idx):
return self._dex.classdefitems[idx]
def getClassNameByIdx(self, idx):
return self.getClassByIdx( idx ).getName()
def getTypeByIdx(self, idx):
return self._dex.typeiditems[idx]
def getTypeNameByIdx(self, idx):
return self.getTypeByIdx( idx ).getName()
class DexFile:
def __init__(self, data):
self._data = data
self._resolver = ObjResolver( self )
self._parse( data )
#just preventing DoS attacks
assert( self.class_defs_size < 100000 )
assert( self.string_ids_size < 100000 )
assert( self.type_ids_size < 100000 )
self.classdefitems = { idx:class_def_item( self._resolver, data, offset ) for (idx,offset) in map(lambda idx: (idx,self.class_defs_off+(32*idx)), range( self.class_defs_size )) }
self.stringiditems = { idx:string_id_item( self._resolver, data, offset ) for (idx,offset) in map(lambda idx: (idx,self.string_ids_off+(4*idx)), range( self.string_ids_size )) }
self.stringdataitems = { offset:string_data_item( self._resolver, data, offset ) for offset in map(lambda iditem: iditem['string_data_off'], self.stringiditems.values()) }
self.typeiditems = { idx:type_id_item( self._resolver, data, offset ) for (idx,offset) in map(lambda idx: (idx,self.type_ids_off+(4*idx)), range( self.type_ids_size )) }
self.methoditems = { idx:method_id_item( self._resolver, data, offset ) for (idx,offset) in map(lambda idx: (idx,self.method_ids_off+(8*idx)), range( self.method_ids_size )) }
def _parse(self, data):
assert( 104 <= len( data ) )
(self.magic, self.checksum, self.signature) = struct.unpack_from( '8sI20s', data, 0 )
(self.string_ids_size, self.string_ids_off) = struct.unpack_from( 'II', data, 56 )
(self.type_ids_size, self.type_ids_off) = struct.unpack_from( 'II', data, 64 )
(self.class_defs_size, self.class_defs_off) = struct.unpack_from( 'II', data, 96 )
(self.method_ids_size, self.method_ids_off) = struct.unpack_from( 'II', data, 88 )
def fixChecksum(self):
struct.pack_into( 'I', self._data, 8, (zlib.adler32( self._data[12:],1 ) % (2**32)) )
def setSignature(self, signature):
assert( len(signature) == 40 )
sig = []
for i in range(20):
sig.append( int( signature[i*2:(i*2)+2], 16 ) )
struct.pack_into( 'B'*20, self._data, 12, *sig )
class DexHeaderObj(dict):
def __init__(self, resolver, data, offset):
dict.__init__(self)
self._resolver = resolver
self._offset = offset
self._data = data
self._fmt = []
def _easyParser(self, data, offset, layout):
pos = offset
for (key, fmt_str) in layout:
size = struct.Struct( fmt_str ).size
assert( pos+size <= len( data ) )
(self[key],) = struct.unpack_from( fmt_str, data, pos )
pos += size
def _parse( self, data, offset ):
self._easyParser( data, offset, self._fmt )
def _parseULEB128(self, data, offset):
def isHighBitSet(byte):
return (byte & 0x80) == 0x80
assert( offset+5 <= len(data) )
(byte0, byte1, byte2, byte3, byte4) = struct.unpack_from( 'BBBBB', data, offset )
value = (byte0 & 0x7f)
bytelen = 1
if isHighBitSet( byte0 ):
bytelen += 1
value = (value & 0xff) | ((byte1 & 0x7f)<<7)
if isHighBitSet( byte1 ):
bytelen += 1
value = (value & 0xffff) | ((byte2 & 0x7f)<<14)
if isHighBitSet( byte2 ):
bytelen += 1
value = (value & 0xffffff) | ((byte3 & 0x7f)<<21)
if isHighBitSet( byte3 ):
bytelen += 1
value = (value & 0xffffffff) | ((byte4 & 0x7f)<<28)
value = (value & 0xffffffff) #make sure it is only 32bit long
return (value, bytelen)
class class_def_item(DexHeaderObj):
def __init__(self, resolver, data, offset):
DexHeaderObj.__init__( self, resolver, data, offset )
self._fmt = [
('class_idx','I'),
('access_flags','I'),
('superclass_idx','I'),
('interfaces_off','I'),
('source_file_idx','I'),
('annotations_off','I'),
('class_data_off','I'),
('static_values_off','I'),
]
self._parse( data, offset )
def getFlags(self):
return self['access_flags']
def setFlags(self, value):
assert( int(value) >= 0 and int( value ) <= 0xffffffff )
self['access_flags'] = value
struct.pack_into( 'I', self._data, self._offset+4, value )
def getName(self):
return self._resolver.getTypeNameByIdx( self['class_idx'] )
def getClassData(self):
return class_data_item( self._resolver, self._data, self['class_data_off'] )
class class_data_item(DexHeaderObj):
def __init__(self, resolver, data, offset):
DexHeaderObj.__init__( self, resolver, data, offset )
self._fmt = []
self._parse( data )
def _parse(self, data):
pos = 0
(value, bytelen) = self._parseULEB128( data, self._offset+pos )
self['static_fields_size'] = value
pos += bytelen
(value, bytelen) = self._parseULEB128( data, self._offset+pos )
self['instance_fields_size'] = value
pos += bytelen
(value, bytelen) = self._parseULEB128( data, self._offset+pos )
self['direct_methods_size'] = value
pos += bytelen
(value, bytelen) = self._parseULEB128( data, self._offset+pos )
self['virtual_methods_size'] = value
pos += bytelen
offset = self._offset+pos
self['static_fields'] = {}
for idx in range( self['static_fields_size'] ):
self['static_fields'][idx] = encoded_field( self._resolver, data, offset )
offset += self['static_fields'][idx].getLen()
self['instance_fields'] = {}
for idx in range( self['instance_fields_size'] ):
self['instance_fields'][idx] = encoded_field( self._resolver, data, offset )
offset += self['instance_fields'][idx].getLen()
self['direct_methods'] = {}
for idx in range( self['direct_methods_size'] ):
self['direct_methods'][idx] = encoded_method( self._resolver, data, offset )
offset += self['direct_methods'][idx].getLen()
self['virtual_methods'] = {}
for idx in range( self['virtual_methods_size'] ):
self['virtual_methods'][idx] = encoded_method( self._resolver, data, offset )
offset += self['virtual_methods'][idx].getLen()
def getDirectEncodedMethod(self, wanted_idx):
cur = 0
for idx in range( self['direct_methods_size'] ):
method = self['direct_methods'][idx]
cur += method['method_idx_diff']
if cur > wanted_idx:
return None #no method in this class with this index
if cur == wanted_idx:
return method
return None
def getVirtualEncodedMethod(self, idx):
cur = 0
for idx in range( self['virtual_methods_size'] ):
method = self['virtual_methods'][idx]
cur += method['method_idx_diff']
if cur > wanted_idx:
return None #no method in this class with this index
if cur == wanted_idx:
return method
return None
class encoded_field(DexHeaderObj):
def __init__(self, resolver, data, offset):
DexHeaderObj.__init__( self, resolver, data, offset )
self._fmt = []
self._parse( data )
def _parse(self, data):
self.len = 0
(value, bytelen) = self._parseULEB128( data, self._offset+self.len )
self['field_idx_diff'] = value
self.len += bytelen
(value, bytelen) = self._parseULEB128( data, self._offset+self.len )
self['access_flags'] = value
self.len += bytelen
def getLen(self):
return self.len
class encoded_method(DexHeaderObj):
def __init__(self, resolver, data, offset):
DexHeaderObj.__init__( self, resolver, data, offset )
self._fmt = []
self._parse( data )
def _parse(self, data):
self.len = 0
(value, bytelen) = self._parseULEB128( data, self._offset+self.len )
self['method_idx_diff'] = value
self.len += bytelen
(value, bytelen) = self._parseULEB128( data, self._offset+self.len )
self['access_flags'] = value
self.len += bytelen
(value, bytelen) = self._parseULEB128( data, self._offset+self.len )
self['code_off'] = value
self.len += bytelen
def getLen(self):
return self.len
def getCodeItem(self):
return code_item( self._resolver, self._data, self['code_off'] )
class string_id_item(DexHeaderObj):
def __init__(self, resolver, data, offset):
DexHeaderObj.__init__( self, resolver, data, offset )
self._fmt = [
('string_data_off','I'),
]
self._parse( data, offset )
class string_data_item(DexHeaderObj):
def __init__(self, resolver, data, offset):
DexHeaderObj.__init__( self, resolver, data, offset )
self._parse( data )
def _parse(self, data):
(size, bytelen) = self._parseULEB128( data, self._offset )
self['utf16_size'] = size
assert( self._offset+bytelen+self['utf16_size'] <= len(data) )
self['data'] = ''.join( struct.unpack_from( 's'*self['utf16_size'], data, self._offset+bytelen ) )
class type_id_item(DexHeaderObj):
def __init__(self, resolver, data, offset):
DexHeaderObj.__init__( self, resolver, data, offset )
self._fmt = [
('descriptor_idx','I'),
]
self._parse( data, offset )
def getName(self):
return self._resolver.getStringByIdx(self['descriptor_idx'])
class method_id_item(DexHeaderObj):
def __init__(self, resolver, data, offset):
DexHeaderObj.__init__( self, resolver, data, offset )
self._fmt = [
('class_idx','H'),
('proto_idx','H'),
('name_idx','I'),
]
self._parse( data, offset )
def getName(self):
return self._resolver.getStringByIdx(self['name_idx'])
class code_item(DexHeaderObj):
def __init__(self, resolver, data, offset):
DexHeaderObj.__init__( self, resolver, data, offset )
self._fmt = [
('registers_size','H'),
('ins_size','H'),
('outs_size','H'),
('tries_size','H'),
('debug_info_off','I'),
('insns_size','I'),
]
self._parse( data, offset )
self._insOffset = offset + struct.calcsize(''.join(map(lambda x: x[1], self._fmt)))
self._parseCode()
#extend to padding, tries and handlers
def _parseCode(self):
self['insns'] = struct.unpack_from( 'B'*2*self['insns_size'], self._data, self._insOffset )
def getCode(self):
return self['insns']
def setCode(self, ins):
insout = map(ord, ins)
struct.pack_into( 'B'*min( self['insns_size']*2, len(ins) ), self._data, self._insOffset, *insout )
if __name__ == "__main__":
if not len(sys.argv) == 2:
print "USAGE: %s <dexfile>"%sys.argv[0]
exit(1)
filename = sys.argv[1]
data = array.array('c', open(filename, 'rb').read() )
dexfile = DexFile(data)
dexfile.fixChecksum()
file(filename, 'wb').write(dexfile._data)