import pwnypack.target
import struct
__all__ = [
'pack',
'unpack',
'pack_size',
'P',
'p',
'U',
'u',
]
def pack(fmt, *args, **kwargs):
"""pack(fmt, v1, v2, ..., endian=None, target=None)
Return a string containing the values v1, v2, ... packed according to the
given format. The actual packing is performed by ``struct.pack`` but the
byte order will be set according to the given `endian`, `target` or
byte order of the global target.
Args:
fmt(str): The format string.
v1,v2,...: The values to pack.
endian(:class:`~pwnypack.target.Target.Endian`): Override the default
byte order. If ``None``, it will look at the byte order of
the ``target`` argument.
target(:class:`~pwnypack.target.Target`): Override the default byte
order. If ``None``, it will look at the byte order of
the global :data:`~pwnypack.target.target`.
Returns:
bytes: The provided values packed according to the format.
"""
endian, target = kwargs.get('endian'), kwargs.get('target')
endian = endian if endian is not None else target.endian if target is not None else pwnypack.target.target.endian
if fmt and fmt[0] not in '@=<>!':
if endian is pwnypack.target.Target.Endian.little:
fmt = '<' + fmt
elif endian is pwnypack.target.Target.Endian.big:
fmt = '>' + fmt
else:
raise NotImplementedError('Unsupported endianness: %s' % endian)
return struct.pack(fmt, *args)
def unpack(fmt, data, endian=None, target=None):
"""
Unpack the string (presumably packed by pack(fmt, ...)) according to the
given format. The actual unpacking is performed by ``struct.unpack``
but the byte order will be set according to the given `endian`, `target`
or byte order of the global target.
Args:
fmt(str): The format string.
data(bytes): The data to unpack.
endian(:class:`~pwnypack.target.Target.Endian`): Override the default
byte order. If ``None``, it will look at the byte order of
the ``target`` argument.
target(:class:`~pwnypack.target.Target`): Override the default byte
order. If ``None``, it will look at the byte order of
the global :data:`~pwnypack.target.target`.
Returns:
list: The unpacked values according to the format.
"""
endian = endian if endian is not None else target.endian if target is not None else pwnypack.target.target.endian
if fmt and fmt[0] not in '@=<>!':
if endian is pwnypack.target.Target.Endian.little:
fmt = '<' + fmt
elif endian is pwnypack.target.Target.Endian.big:
fmt = '>' + fmt
else:
raise NotImplementedError('Unsupported endianness: %s' % endian)
return struct.unpack(fmt, data)
def pack_size(fmt, endian=None, target=None):
endian = endian if endian is not None else target.endian if target is not None else pwnypack.target.target.endian
if fmt and fmt[0] not in '@=<>!':
if endian is pwnypack.target.Target.Endian.little:
fmt = '<' + fmt
elif endian is pwnypack.target.Target.Endian.big:
fmt = '>' + fmt
else:
raise NotImplementedError('Unsupported endianness: %s' % endian)
return struct.calcsize(fmt)
def _pack_closure(fmt):
return lambda value, endian=None, target=None: pack(fmt, value, endian=endian, target=target)
def _unpack_closure(fmt):
return lambda data, endian=None, target=None: unpack(fmt, data, endian=endian, target=target)[0]
for _w, _f in ((8, 'b'), (16, 'h'), (32, 'l'), (64, 'q')):
locals().update({
'p%d' % _w: _pack_closure(_f),
'P%d' % _w: _pack_closure(_f.upper()),
'u%d' % _w: _unpack_closure(_f),
'U%d' % _w: _unpack_closure(_f.upper()),
})
locals()['p%d' % _w].__doc__ = '''Pack signed %d bit integer. Alias for ``pack('%s', ...)``.''' % (_w, _f)
locals()['P%d' % _w].__doc__ = '''Pack unsigned %d bit integer. Alias for ``pack('%s', ...)``.''' % (_w, _f.upper())
locals()['u%d' % _w].__doc__ = '''Unpack signed %d bit integer. Alias for ``unpack('%s', ...)``.''' % (_w, _f)
locals()['U%d' % _w].__doc__ = '''Unpack unsigned %d bit integer. Alias for ``unpack('%s', ...)``.''' % \
(_w, _f.upper())
__all__.extend([
'p%d' % _w,
'P%d' % _w,
'u%d' % _w,
'U%d' % _w,
])
del _w, _f, _pack_closure, _unpack_closure
def _get_bits(bits=None, target=None):
"""
Determine the number of bits to pack/unpack.
"""
if bits is not None:
bits = int(bits)
if bits in (8, 16, 32, 64):
return bits
else:
raise ValueError('bits needs to be 8, 16, 32 or 64')
else:
return int((target if target is not None else pwnypack.target.target).bits)
def P(value, bits=None, endian=None, target=None):
"""
Pack an unsigned pointer for a given target.
Args:
value(int): The value to pack.
bits(:class:`~pwnypack.target.Target.Bits`): Override the default
word size. If ``None`` it will look at the word size of
``target``.
endian(:class:`~pwnypack.target.Target.Endian`): Override the default
byte order. If ``None``, it will look at the byte order of
the ``target`` argument.
target(:class:`~pwnypack.target.Target`): Override the default byte
order. If ``None``, it will look at the byte order of
the global :data:`~pwnypack.target.target`.
"""
return globals()['P%d' % _get_bits(bits, target)](value, endian=endian, target=target)
def p(value, bits=None, endian=None, target=None):
"""
Pack a signed pointer for a given target.
Args:
value(int): The value to pack.
bits(:class:`pwnypack.target.Target.Bits`): Override the default
word size. If ``None`` it will look at the word size of
``target``.
endian(:class:`~pwnypack.target.Target.Endian`): Override the default
byte order. If ``None``, it will look at the byte order of
the ``target`` argument.
target(:class:`~pwnypack.target.Target`): Override the default byte
order. If ``None``, it will look at the byte order of
the global :data:`~pwnypack.target.target`.
"""
return globals()['p%d' % _get_bits(bits, target)](value, endian=endian, target=target)
def U(data, bits=None, endian=None, target=None):
"""
Unpack an unsigned pointer for a given target.
Args:
data(bytes): The data to unpack.
bits(:class:`pwnypack.target.Target.Bits`): Override the default
word size. If ``None`` it will look at the word size of
``target``.
endian(:class:`~pwnypack.target.Target.Endian`): Override the default
byte order. If ``None``, it will look at the byte order of
the ``target`` argument.
target(:class:`~pwnypack.target.Target`): Override the default byte
order. If ``None``, it will look at the byte order of
the global :data:`~pwnypack.target.target`.
Returns:
int: The pointer value.
"""
return globals()['U%d' % _get_bits(bits, target)](data, endian=endian, target=target)
def u(data, bits=None, endian=None, target=None):
"""
Unpack a signed pointer for a given target.
Args:
data(bytes): The data to unpack.
bits(:class:`pwnypack.target.Target.Bits`): Override the default
word size. If ``None`` it will look at the word size of
``target``.
endian(:class:`~pwnypack.target.Target.Endian`): Override the default
byte order. If ``None``, it will look at the byte order of
the ``target`` argument.
target(:class:`~pwnypack.target.Target`): Override the default byte
order. If ``None``, it will look at the byte order of
the global :data:`~pwnypack.target.target`.
Returns:
int: The pointer value.
"""
return globals()['u%d' % _get_bits(bits, target)](data, endian=endian, target=target)
