python3 support for SaltCrypt

[slieberth]

Hi Istvan, Hi Christian

when using AVP 'Tunnel-Password' with python3 I get following error:

 File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pyrad/packet.py", line 254, in _EncodeKeyValues
    return (key, [tag + self._EncodeValue(attr, v) for v in values])
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pyrad/packet.py", line 254, in <listcomp>
    return (key, [tag + self._EncodeValue(attr, v) for v in values])
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pyrad/packet.py", line 235, in _EncodeValue
    result = self.SaltCrypt(result)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pyrad/packet.py", line 567, in SaltCrypt
    salt = chr(ord(salt[0]) | 1 << 7)+salt[1]
TypeError: ord() expected string of length 1, but int found

this is due to strict.pack behavior in python3, which returns bytes (instead of string in python 2)

potential fix, which I have tested:

    def SaltCrypt(self, value):
        """Salt Encryption

        :param value:    plaintext value
        :type password:  unicode string
        :return:         obfuscated version of the value
        :rtype:          binary string
        """

        if isinstance(value, six.text_type):
            value = value.encode('utf-8')

        if self.authenticator is None:
            # self.authenticator = self.CreateAuthenticator()
            self.authenticator = 16 * six.b('\x00')

        if six.PY3:
            random_value = 32768 + random_generator.randrange(0, 32767)
            salt_raw = struct.pack('!H', random_value )
            salt_str = chr(salt_raw[0]) + chr(salt_raw[0])
            salt = six.b(salt_str)
            result = salt
        else:
            random_value = random_generator.randrange(0, 65535)
            salt = struct.pack('!H', random_value )
            salt = chr(ord(salt[0]) | 1 << 7)+salt[1]
            result = six.b(salt)

        #salt = struct.pack('!H', random_generator.randrange(0, 65535))
        #salt = chr(ord(salt[0]) | 1 << 7)+salt[1]

        length = struct.pack("B", len(value))
        buf = length + value
        if len(buf) % 16 != 0:
            buf += six.b('\x00') * (16 - (len(buf) % 16))

        #result = six.b(salt)

        last = self.authenticator + salt
        while buf:
            hash = md5_constructor(self.secret + last).digest()
            if six.PY3:
                for i in range(16):
                    result += bytes((hash[i] ^ buf[i],))
            else:
                for i in range(16):
                    result += chr(ord(hash[i]) ^ ord(buf[i]))

            last = result[-16:]
            buf = buf[16:]

        return result

regards Stefan

[Istvan91]

Fixed in #128