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from sploit.arch import arch, itob
from sploit.symtbl import Symtbl
class Payload:
MAGIC = b'\xef'
def __init__(self, **kwargs):
self.payload = b''
self.sym = Symtbl(**kwargs)
self.ctrs = {}
def __len__(self):
return len(self.payload)
def __call__(self, badbytes=b''):
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, sym):
if sym is not None: return sym
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.map(0), sym, len(self))
self.payload += value
return self
def _prepend(self, value, sym):
self.sym.adjust(len(value))
setattr(self.sym.map(0), sym, 0)
self.payload = value + self.payload
return self
def bin(self, *values, sym=None):
return self._append(b''.join(values), sym=self._name('bin', sym))
def str(self, *values, sym=None):
values = [ v.encode() + b'\x00' for v in values ]
return self.bin(*values, sym=self._name('str', sym))
def int(self, *values, sym=None, signed=False):
values = [ itob(v, signed=signed) for v in values ]
return self.bin(*values, sym=self._name('int', sym))
def ret(self, *values, sym=None):
return self.int(*values, sym=self._name('ret', sym))
def sbp(self, *values, sym=None):
if len(values) == 0:
return self.rep(self.MAGIC, arch.wordsize, sym=self._name('sbp', sym))
return self.int(*values, sym=self._name('sbp', sym))
def rep(self, value, size, sym=None):
return self.bin(self._rep_helper(value, size), sym=self._name('rep', sym))
def pad(self, size, value=None, sym=None):
return self.bin(self._pad_helper(size, value), sym=self._name('pad', sym))
def pad_front(self, size, value=None, sym=None):
return self._prepend(self._pad_helper(size, value), sym=self._name('pad', sym))
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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