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# Volatools Basic
# Copyright (C) 2007 Komoku, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or (at
# your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
"""
@author: AAron Walters and Nick Petroni
@license: GNU General Public License 2.0 or later
@contact: awalters@komoku.com, npetroni@komoku.com
@organization: Komoku, Inc.
"""
import struct
builtin_types = {
'int': (4, 'i'),
'long': (4, 'i'),
'unsigned long': (4, 'I'),
'unsigned int': (4, 'I'),
'address': (4, 'I'),
'char': (1, 'c'),
'unsigned char': (1, 'B'),
'unsigned short': (2, 'H'),
'short': (2, 'h'),
'long long': (8, 'q'),
'unsigned long long': (8, 'Q'),
'pointer': (4, 'I'),
}
def obj_size(types, objname):
if objname not in types:
raise Exception('Invalid type %s not in types' % objname)
return types[objname][0]
def builtin_size(builtin):
if builtin not in builtin_types:
raise Exception('Invalid built-in type %s' % builtin)
return builtin_types[builtin][0]
def read_value(addr_space, value_type, vaddr):
"""
Read the low-level value for a built-in type.
"""
if value_type not in builtin_types:
raise Exception('Invalid built-in type %s' % value_type)
type_unpack_char = builtin_types[value_type][1]
type_size = builtin_types[value_type][0]
buf = addr_space.read(vaddr, type_size)
if buf is None:
return None
try:
(val,) = struct.unpack(type_unpack_char, buf)
except Exception:
return None
return val
def read_unicode_string(addr_space, types, member_list, vaddr):
offset = 0
if len(member_list) > 1:
(offset, current_type) = get_obj_offset(types, member_list)
buf = read_obj(addr_space, types, ['_UNICODE_STRING', 'Buffer'], vaddr + offset)
length = read_obj(addr_space, types, ['_UNICODE_STRING', 'Length'], vaddr + offset)
if length == 0x0:
return ""
if buf is None or length is None:
return None
readBuf = read_string(addr_space, types, ['char'], buf, length)
if readBuf is None:
return None
try:
readBuf = readBuf.decode('UTF-16').encode('ascii')
except Exception:
return None
return readBuf
def read_string(addr_space, types, member_list, vaddr, max_length=256):
offset = 0
if len(member_list) > 1:
(offset, current_type) = get_obj_offset(types, member_list)
val = addr_space.read(vaddr + offset, max_length)
return val
def read_null_string(addr_space, types, member_list, vaddr, max_length=256):
string = read_string(addr_space, types, member_list, vaddr, max_length)
if string is None:
return None
if string.find('\0') == -1:
return string
(string, none) = string.split('\0', 1)
return string
def get_obj_offset(types, member_list):
"""
Returns the (offset, type) pair for a given list
"""
member_list.reverse()
current_type = member_list.pop()
offset = 0
current_member = 0
member_dict = None
while len(member_list) > 0:
if current_type == 'array':
if member_dict:
current_type = member_dict[current_member][1][2][0]
if current_type in builtin_types:
current_type_size = builtin_size(current_type)
else:
current_type_size = obj_size(types, current_type)
index = member_list.pop()
offset += index * current_type_size
continue
elif current_type not in types:
raise Exception('Invalid type ' + current_type)
member_dict = types[current_type][1]
current_member = member_list.pop()
if current_member not in member_dict:
raise Exception('Invalid member %s in type %s' % (current_member, current_type))
offset += member_dict[current_member][0]
current_type = member_dict[current_member][1][0]
return offset, current_type
def read_obj(addr_space, types, member_list, vaddr):
"""
Read the low-level value for some complex type's member.
The type must have members.
"""
if len(member_list) < 2:
raise Exception('Invalid type/member ' + str(member_list))
(offset, current_type) = get_obj_offset(types, member_list)
return read_value(addr_space, current_type, vaddr + offset)
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