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from sploit.arch import arch, itob
from sploit.mem import Symtbl
class Payload(Symtbl):
MAGIC = b'\xef'
def __init__(self, **kwargs):
super().__init__(**kwargs)
self = self._namesp
self.payload = b''
self.ctrs = {}
def __len__(self):
return len(self._namesp.payload)
def __call__(self, badbytes=b''):
self = self._namesp
found = [ hex(x) for x in set(self.payload).intersection(badbytes) ]
if len(found) > 0:
raise Exception(f'Payload: bad bytes in content: {found}')
return self.payload
def __name(self, kind):
self = self._namesp
try: ctr = self.ctrs[kind]
except: ctr = 0
self.ctrs[kind] = ctr + 1
return f'{kind}_{ctr}'
def __append(self, value, sym):
setattr(self, sym, len(self))
self._namesp.payload += value
return self
def __prepend(self, value, sym):
self.adjust(len(value))
setattr(self, sym, 0)
self._namesp.payload = value + self._namesp.payload
return self
def bin(self, *values, sym=None):
return self.__append(b''.join(values), sym or self.__name('bin'))
def str(self, *values, sym=None):
values = [ v.encode() + b'\x00' for v in values ]
return self.bin(*values, sym=(sym or self.__name('str')))
def int(self, *values, sym=None, signed=False):
values = [ itob(v, signed=signed) for v in values ]
return self.bin(*values, sym=(sym or self.__name('int')))
def ret(self, *values, sym=None):
return self.int(*values, sym=(sym or self.__name('ret')))
def sbp(self, *values, sym=None):
if len(values) == 0:
return self.rep(self.MAGIC, arch.wordsize, sym or self.__name('sbp'))
return self.int(*values, sym=(sym or self.__name('sbp')))
def rep(self, value, size, sym=None):
return self.bin(self.__rep_helper(value, size), sym=(sym or self.__name('rep')))
def pad(self, size, value=None, sym=None):
return self.bin(self.__pad_helper(size, value), sym=(sym or self.__name('pad')))
def pad_front(self, size, value=None, sym=None):
return self.__prepend(self.__pad_helper(size, value), sym or self.__name('pad'))
def __rep_helper(self, value, size, *, explain=''):
if size < 0:
raise Exception(f'Payload: {explain}rep: available space is negative')
if (size := size / len(value)) != int(size):
raise Exception(f'Payload: {explain}rep: element does not divide the space evenly')
return value * int(size)
def __pad_helper(self, size, value):
return self.__rep_helper(value or arch.nopcode, size - len(self), explain='pad: ')
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