Python 2 str.decode('hex') in Python 3?

Question

I want to send hex encoded data to another client via sockets in python. I managed to do everything some time ago in python 2. Now I want to port it to python 3.

Data looks like this:

""" 16 03 02 """

Then I used this function to get it into a string:

x.replace(' ', '').replace('\n', '').decode('hex')

It then looks like this (which is a type str by the way):

'\x16\x03\x02'

Now I managed to find this in python 3:

codecs.decode('160302', 'hex')

but it returns another type:

b'\x16\x03\x02'

And since everything I encode is not a proper language, i cannot use utf-8 or some decoders, as there are invalid bytes in it (e.g. \x00, \xFF). Any ideas on how I can get the string solution escaped again just like in python 2?

Thanks

Answer 1

'str' objects in python 3 are not sequences of bytes but sequences of unicode code points.

If by "send data" you mean calling send then bytes is the right type to use.

If you really want the string (not 3 bytes but 12 unicode code points):

>>> import codecs
>>> s = str(codecs.decode('16ff00', 'hex'))[2:-1]
>>> s
'\\x16\\xff\\x00'
>>> print(s)
\x16\xff\x00

Note that you need to double backslashes in order to represent them in code.

Answer 2

There is an standard solution for Python2 and Python3. No imports needed: hex_string = """ 16 03 02 """ some_bytes = bytearray.fromhex(hex_string)

In python3 you can treat it like an str (slicing it, iterate, etc) also you can add byte-strings: b'\x00', b'text' or bytes('text','utf8')

You also mentioned something about to encode "utf-8". So you can do it easily with: some_bytes.encode()

As you can see you don't need to clean it. This function is very effective. If you want to return to hexadecimal string: some_bytes.hex() will do it for you.

Answer 3

a = """ 16 03 02 """.encode("utf-8")
#Send things over socket
print(a.decode("utf-8"))

Why not encoding with UTF-8, sending with socket and decoding with UTF-8 again ?