first commit

librespot/util.py

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+from Cryptodome import Random
+import binascii
+import math
+
+
+def bytes_to_hex(buffer: bytes) -> str:
+    """
+    Convert bytes to hex
+    Args:
+        buffer: Bytes to convert
+    Returns:
+        hex
+    """
+    return binascii.hexlify(buffer).decode()
+
+
+def hex_to_bytes(s: str) -> bytes:
+    return binascii.unhexlify(s)
+
+
+def int_to_bytes(i: int):
+    """
+    Convert an integer to a byte(s)
+    Args:
+        i: Integer to convert
+    Returns:
+        bytes
+    """
+    width = i.bit_length()
+    width += 8 - ((width % 8) or 8)
+    fmt = '%%0%dx' % (width // 4)
+    return b"\x00" if i == 0 else binascii.unhexlify(fmt % i)
+
+
+def random_hex_string(length: int):
+    buffer = Random.get_random_bytes(int(length / 2))
+    return bytes_to_hex(buffer)
+
+
+class Base62:
+    standard_base = 256
+    target_base = 62
+    alphabet: bytes
+    lookup: bytearray
+
+    def __init__(self, alphabet: bytes):
+        self.alphabet = alphabet
+        self.create_lookup_table()
+
+    @staticmethod
+    def create_instance_with_inverted_character_set():
+        return Base62(Base62.CharacterSets.inverted)
+
+    def encode(self, message: bytes, length: int = -1):
+        indices = self.convert(message, self.standard_base, self.target_base,
+                               length)
+        return self.translate(indices, self.alphabet)
+
+    def decode(self, encoded: bytes, length: int = -1):
+        prepared = self.translate(encoded, self.lookup)
+        return self.convert(prepared, self.target_base, self.standard_base,
+                            length)
+
+    def translate(self, indices: bytes, dictionary: bytes):
+        translation = bytearray(len(indices))
+        for i in range(len(indices)):
+            translation[i] = dictionary[int.from_bytes(bytes([indices[i]]), "big")]
+        return translation
+
+    def convert(self, message: bytes, source_base: int, target_base: int,
+                length: int):
+        estimated_length = self.estimate_output_length(
+            len(message), source_base, target_base) if length == -1 else length
+        out = b""
+        source = message
+        while len(source) > 0:
+            quotient = b""
+            remainder = 0
+            for b in source:
+                accumulator = int(b & 0xff) + remainder * source_base
+                digit = int(
+                    (accumulator - (accumulator % target_base)) / target_base)
+                remainder = int(accumulator % target_base)
+                if len(quotient) > 0 or digit > 0:
+                    quotient += bytes([digit])
+            out += bytes([remainder])
+            source = quotient
+        if len(out) < estimated_length:
+            size = len(out)
+            for _ in range(estimated_length - size):
+                out += bytes([0])
+            return self.reverse(out)
+        if len(out) > estimated_length:
+            return self.reverse(out[:estimated_length])
+        return self.reverse(out)
+
+    def estimate_output_length(self, input_length: int, source_base: int,
+                               target_base: int):
+        return int(
+            math.ceil((math.log(source_base) / math.log(target_base)) *
+                      input_length))
+
+    def reverse(self, arr: bytes):
+        length = len(arr)
+        reversed_arr = bytearray(length)
+        for i in range(length):
+            reversed_arr[length - i - 1] = arr[i]
+        return bytes(reversed_arr)
+
+    def create_lookup_table(self):
+        self.lookup = bytearray(256)
+        for i in range(len(self.alphabet)):
+            self.lookup[self.alphabet[i]] = i & 0xff
+
+    class CharacterSets:
+        gmp = b'0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'
+        inverted = b'0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'