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import builtins
import sys
import hashlib
from typing import Optional, Union, Callable, List
bytes_ = builtins.bytes # alias the stdlib type but ew
def unicode(text: Union[bytes_, str]) -> str:
if not isinstance(text, str):
return text.decode('utf-8')
else:
return text
def bytes(text: Optional[Union[str, bytes_]]) -> bytes_:
"""
Convert Unicode text to UTF-8 encoded bytes.
Since Python 2.6+ and Python 3+ have similar but incompatible
signatures, this function unifies the two to keep code sane.
:param text: Unicode text to convert to bytes
:rtype: bytes (Python3), str (Python2.6+)
"""
if text is None:
return b''
if isinstance(text, builtins.bytes):
# We already have bytes, so do nothing
return text
if isinstance(text, list):
# Convert a list of integers to bytes
return builtins.bytes(text)
else:
# Convert UTF-8 text to bytes
return builtins.bytes(text, encoding='utf-8')
def quote(text: Union[str, bytes_]) -> bytes_:
"""
Enclose in quotes and escape internal slashes and double quotes.
:param text: A Unicode or byte string.
"""
text = bytes(text)
return b'"' + text.replace(b'\\', b'\\\\').replace(b'"', b'\\"') + b'"'
def num_to_bytes(num: int) -> bytes_:
"""
Convert an integer into a four byte sequence.
:param integer num: An integer to convert to its byte representation.
"""
bval = b''
bval += bytes(chr(0xFF & (num >> 24)))
bval += bytes(chr(0xFF & (num >> 16)))
bval += bytes(chr(0xFF & (num >> 8)))
bval += bytes(chr(0xFF & (num >> 0)))
return bval
def bytes_to_num(bval: bytes_) -> int:
"""
Convert a four byte sequence to an integer.
:param bytes bval: A four byte sequence to turn into an integer.
"""
num = 0
num += (bval[0] << 24)
num += (bval[1] << 16)
num += (bval[2] << 8)
num += (bval[3])
return num
def XOR(x: bytes_, y: bytes_) -> bytes_:
"""
Return the results of an XOR operation on two equal length byte strings.
:param bytes x: A byte string
:param bytes y: A byte string
:rtype: bytes
"""
# This operation is faster with a list comprehension than with a
# generator, as of 2016 on python 3.5.
return builtins.bytes([a ^ b for a, b in zip(x, y)])
def hash(name: str) -> Optional[Callable]:
"""
Return a hash function implementing the given algorithm.
:param name: The name of the hashing algorithm to use.
:type name: string
:rtype: function
"""
name = name.lower()
if name.startswith('sha-'):
name = 'sha' + name[4:]
if name in dir(hashlib):
return getattr(hashlib, name)
return None
def hashes() -> List[str]:
"""
Return a list of available hashing algorithms.
:rtype: list of strings
"""
t = []
if 'md5' in dir(hashlib):
t = ['MD5']
if 'md2' in dir(hashlib):
t += ['MD2']
hashes = ['SHA-' + h[3:] for h in dir(hashlib) if h.startswith('sha')]
return t + hashes
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