diff options
Diffstat (limited to 'Lib/base64.py')
| -rwxr-xr-x | Lib/base64.py | 370 |
1 files changed, 281 insertions, 89 deletions
diff --git a/Lib/base64.py b/Lib/base64.py index b6e82b6..640f787 100755 --- a/Lib/base64.py +++ b/Lib/base64.py @@ -1,6 +1,6 @@ #! /usr/bin/env python3 -"""RFC 3548: Base16, Base32, Base64 Data Encodings""" +"""Base16, Base32, Base64 (RFC 3548), Base85 and Ascii85 data encodings""" # Modified 04-Oct-1995 by Jack Jansen to use binascii module # Modified 30-Dec-2003 by Barry Warsaw to add full RFC 3548 support @@ -17,6 +17,8 @@ __all__ = [ # Generalized interface for other encodings 'b64encode', 'b64decode', 'b32encode', 'b32decode', 'b16encode', 'b16decode', + # Base85 and Ascii85 encodings + 'b85encode', 'b85decode', 'a85encode', 'a85decode', # Standard Base64 encoding 'standard_b64encode', 'standard_b64decode', # Some common Base64 alternatives. As referenced by RFC 3458, see thread @@ -35,11 +37,13 @@ def _bytes_from_decode_data(s): return s.encode('ascii') except UnicodeEncodeError: raise ValueError('string argument should contain only ASCII characters') - elif isinstance(s, bytes_types): + if isinstance(s, bytes_types): return s - else: - raise TypeError("argument should be bytes or ASCII string, not %s" % s.__class__.__name__) - + try: + return memoryview(s).tobytes() + except TypeError: + raise TypeError("argument should be a bytes-like object or ASCII " + "string, not %r" % s.__class__.__name__) from None # Base64 encoding/decoding uses binascii @@ -54,14 +58,9 @@ def b64encode(s, altchars=None): The encoded byte string is returned. """ - if not isinstance(s, bytes_types): - raise TypeError("expected bytes, not %s" % s.__class__.__name__) # Strip off the trailing newline encoded = binascii.b2a_base64(s)[:-1] if altchars is not None: - if not isinstance(altchars, bytes_types): - raise TypeError("expected bytes, not %s" - % altchars.__class__.__name__) assert len(altchars) == 2, repr(altchars) return encoded.translate(bytes.maketrans(b'+/', altchars)) return encoded @@ -138,53 +137,39 @@ def urlsafe_b64decode(s): # Base32 encoding/decoding must be done in Python -_b32alphabet = { - 0: b'A', 9: b'J', 18: b'S', 27: b'3', - 1: b'B', 10: b'K', 19: b'T', 28: b'4', - 2: b'C', 11: b'L', 20: b'U', 29: b'5', - 3: b'D', 12: b'M', 21: b'V', 30: b'6', - 4: b'E', 13: b'N', 22: b'W', 31: b'7', - 5: b'F', 14: b'O', 23: b'X', - 6: b'G', 15: b'P', 24: b'Y', - 7: b'H', 16: b'Q', 25: b'Z', - 8: b'I', 17: b'R', 26: b'2', - } - -_b32tab = [v[0] for k, v in sorted(_b32alphabet.items())] -_b32rev = dict([(v[0], k) for k, v in _b32alphabet.items()]) - +_b32alphabet = b'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567' +_b32tab2 = None +_b32rev = None def b32encode(s): """Encode a byte string using Base32. s is the byte string to encode. The encoded byte string is returned. """ + global _b32tab2 + # Delay the initialization of the table to not waste memory + # if the function is never called + if _b32tab2 is None: + b32tab = [bytes((i,)) for i in _b32alphabet] + _b32tab2 = [a + b for a in b32tab for b in b32tab] + b32tab = None + if not isinstance(s, bytes_types): - raise TypeError("expected bytes, not %s" % s.__class__.__name__) - quanta, leftover = divmod(len(s), 5) + s = memoryview(s).tobytes() + leftover = len(s) % 5 # Pad the last quantum with zero bits if necessary if leftover: s = s + bytes(5 - leftover) # Don't use += ! - quanta += 1 encoded = bytearray() - for i in range(quanta): - # c1 and c2 are 16 bits wide, c3 is 8 bits wide. The intent of this - # code is to process the 40 bits in units of 5 bits. So we take the 1 - # leftover bit of c1 and tack it onto c2. Then we take the 2 leftover - # bits of c2 and tack them onto c3. The shifts and masks are intended - # to give us values of exactly 5 bits in width. - c1, c2, c3 = struct.unpack('!HHB', s[i*5:(i+1)*5]) - c2 += (c1 & 1) << 16 # 17 bits wide - c3 += (c2 & 3) << 8 # 10 bits wide - encoded += bytes([_b32tab[c1 >> 11], # bits 1 - 5 - _b32tab[(c1 >> 6) & 0x1f], # bits 6 - 10 - _b32tab[(c1 >> 1) & 0x1f], # bits 11 - 15 - _b32tab[c2 >> 12], # bits 16 - 20 (1 - 5) - _b32tab[(c2 >> 7) & 0x1f], # bits 21 - 25 (6 - 10) - _b32tab[(c2 >> 2) & 0x1f], # bits 26 - 30 (11 - 15) - _b32tab[c3 >> 5], # bits 31 - 35 (1 - 5) - _b32tab[c3 & 0x1f], # bits 36 - 40 (1 - 5) - ]) + from_bytes = int.from_bytes + b32tab2 = _b32tab2 + for i in range(0, len(s), 5): + c = from_bytes(s[i: i + 5], 'big') + encoded += (b32tab2[c >> 30] + # bits 1 - 10 + b32tab2[(c >> 20) & 0x3ff] + # bits 11 - 20 + b32tab2[(c >> 10) & 0x3ff] + # bits 21 - 30 + b32tab2[c & 0x3ff] # bits 31 - 40 + ) # Adjust for any leftover partial quanta if leftover == 1: encoded[-6:] = b'======' @@ -196,7 +181,6 @@ def b32encode(s): encoded[-1:] = b'=' return bytes(encoded) - def b32decode(s, casefold=False, map01=None): """Decode a Base32 encoded byte string. @@ -216,9 +200,13 @@ def b32decode(s, casefold=False, map01=None): the input is incorrectly padded or if there are non-alphabet characters present in the input. """ + global _b32rev + # Delay the initialization of the table to not waste memory + # if the function is never called + if _b32rev is None: + _b32rev = {v: k for k, v in enumerate(_b32alphabet)} s = _bytes_from_decode_data(s) - quanta, leftover = divmod(len(s), 8) - if leftover: + if len(s) % 8: raise binascii.Error('Incorrect padding') # Handle section 2.4 zero and one mapping. The flag map01 will be either # False, or the character to map the digit 1 (one) to. It should be @@ -232,42 +220,36 @@ def b32decode(s, casefold=False, map01=None): # Strip off pad characters from the right. We need to count the pad # characters because this will tell us how many null bytes to remove from # the end of the decoded string. - padchars = 0 - mo = re.search(b'(?P<pad>[=]*)$', s) - if mo: - padchars = len(mo.group('pad')) - if padchars > 0: - s = s[:-padchars] + l = len(s) + s = s.rstrip(b'=') + padchars = l - len(s) # Now decode the full quanta - parts = [] - acc = 0 - shift = 35 - for c in s: - val = _b32rev.get(c) - if val is None: - raise binascii.Error('Non-base32 digit found') - acc += _b32rev[c] << shift - shift -= 5 - if shift < 0: - parts.append(binascii.unhexlify(bytes('%010x' % acc, "ascii"))) - acc = 0 - shift = 35 + decoded = bytearray() + b32rev = _b32rev + for i in range(0, len(s), 8): + quanta = s[i: i + 8] + acc = 0 + try: + for c in quanta: + acc = (acc << 5) + b32rev[c] + except KeyError: + raise binascii.Error('Non-base32 digit found') from None + decoded += acc.to_bytes(5, 'big') # Process the last, partial quanta - last = binascii.unhexlify(bytes('%010x' % acc, "ascii")) - if padchars == 0: - last = b'' # No characters - elif padchars == 1: - last = last[:-1] - elif padchars == 3: - last = last[:-2] - elif padchars == 4: - last = last[:-3] - elif padchars == 6: - last = last[:-4] - else: - raise binascii.Error('Incorrect padding') - parts.append(last) - return b''.join(parts) + if padchars: + acc <<= 5 * padchars + last = acc.to_bytes(5, 'big') + if padchars == 1: + decoded[-5:] = last[:-1] + elif padchars == 3: + decoded[-5:] = last[:-2] + elif padchars == 4: + decoded[-5:] = last[:-3] + elif padchars == 6: + decoded[-5:] = last[:-4] + else: + raise binascii.Error('Incorrect padding') + return bytes(decoded) @@ -279,8 +261,6 @@ def b16encode(s): s is the byte string to encode. The encoded byte string is returned. """ - if not isinstance(s, bytes_types): - raise TypeError("expected bytes, not %s" % s.__class__.__name__) return binascii.hexlify(s).upper() @@ -302,7 +282,206 @@ def b16decode(s, casefold=False): raise binascii.Error('Non-base16 digit found') return binascii.unhexlify(s) +# +# Ascii85 encoding/decoding +# + +_a85chars = None +_a85chars2 = None +_A85START = b"<~" +_A85END = b"~>" + +def _85encode(b, chars, chars2, pad=False, foldnuls=False, foldspaces=False): + # Helper function for a85encode and b85encode + if not isinstance(b, bytes_types): + b = memoryview(b).tobytes() + + padding = (-len(b)) % 4 + if padding: + b = b + b'\0' * padding + words = struct.Struct('!%dI' % (len(b) // 4)).unpack(b) + + chunks = [b'z' if foldnuls and not word else + b'y' if foldspaces and word == 0x20202020 else + (chars2[word // 614125] + + chars2[word // 85 % 7225] + + chars[word % 85]) + for word in words] + + if padding and not pad: + if chunks[-1] == b'z': + chunks[-1] = chars[0] * 5 + chunks[-1] = chunks[-1][:-padding] + + return b''.join(chunks) +def a85encode(b, *, foldspaces=False, wrapcol=0, pad=False, adobe=False): + """Encode a byte string using Ascii85. + + b is the byte string to encode. The encoded byte string is returned. + + foldspaces is an optional flag that uses the special short sequence 'y' + instead of 4 consecutive spaces (ASCII 0x20) as supported by 'btoa'. This + feature is not supported by the "standard" Adobe encoding. + + wrapcol controls whether the output should have newline ('\\n') characters + added to it. If this is non-zero, each output line will be at most this + many characters long. + + pad controls whether the input string is padded to a multiple of 4 before + encoding. Note that the btoa implementation always pads. + + adobe controls whether the encoded byte sequence is framed with <~ and ~>, + which is used by the Adobe implementation. + """ + global _a85chars, _a85chars2 + # Delay the initialization of tables to not waste memory + # if the function is never called + if _a85chars is None: + _a85chars = [bytes((i,)) for i in range(33, 118)] + _a85chars2 = [(a + b) for a in _a85chars for b in _a85chars] + + result = _85encode(b, _a85chars, _a85chars2, pad, True, foldspaces) + + if adobe: + result = _A85START + result + if wrapcol: + wrapcol = max(2 if adobe else 1, wrapcol) + chunks = [result[i: i + wrapcol] + for i in range(0, len(result), wrapcol)] + if adobe: + if len(chunks[-1]) + 2 > wrapcol: + chunks.append(b'') + result = b'\n'.join(chunks) + if adobe: + result += _A85END + + return result + +def a85decode(b, *, foldspaces=False, adobe=False, ignorechars=b' \t\n\r\v'): + """Decode an Ascii85 encoded byte string. + + s is the byte string to decode. + + foldspaces is a flag that specifies whether the 'y' short sequence should be + accepted as shorthand for 4 consecutive spaces (ASCII 0x20). This feature is + not supported by the "standard" Adobe encoding. + + adobe controls whether the input sequence is in Adobe Ascii85 format (i.e. + is framed with <~ and ~>). + + ignorechars should be a byte string containing characters to ignore from the + input. This should only contain whitespace characters, and by default + contains all whitespace characters in ASCII. + """ + b = _bytes_from_decode_data(b) + if adobe: + if not (b.startswith(_A85START) and b.endswith(_A85END)): + raise ValueError("Ascii85 encoded byte sequences must be bracketed " + "by {!r} and {!r}".format(_A85START, _A85END)) + b = b[2:-2] # Strip off start/end markers + # + # We have to go through this stepwise, so as to ignore spaces and handle + # special short sequences + # + packI = struct.Struct('!I').pack + decoded = [] + decoded_append = decoded.append + curr = [] + curr_append = curr.append + curr_clear = curr.clear + for x in b + b'u' * 4: + if b'!'[0] <= x <= b'u'[0]: + curr_append(x) + if len(curr) == 5: + acc = 0 + for x in curr: + acc = 85 * acc + (x - 33) + try: + decoded_append(packI(acc)) + except struct.error: + raise ValueError('Ascii85 overflow') from None + curr_clear() + elif x == b'z'[0]: + if curr: + raise ValueError('z inside Ascii85 5-tuple') + decoded_append(b'\0\0\0\0') + elif foldspaces and x == b'y'[0]: + if curr: + raise ValueError('y inside Ascii85 5-tuple') + decoded_append(b'\x20\x20\x20\x20') + elif x in ignorechars: + # Skip whitespace + continue + else: + raise ValueError('Non-Ascii85 digit found: %c' % x) + + result = b''.join(decoded) + padding = 4 - len(curr) + if padding: + # Throw away the extra padding + result = result[:-padding] + return result + +# The following code is originally taken (with permission) from Mercurial + +_b85alphabet = (b"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" + b"abcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~") +_b85chars = None +_b85chars2 = None +_b85dec = None + +def b85encode(b, pad=False): + """Encode an ASCII-encoded byte array in base85 format. + + If pad is true, the input is padded with "\\0" so its length is a multiple of + 4 characters before encoding. + """ + global _b85chars, _b85chars2 + # Delay the initialization of tables to not waste memory + # if the function is never called + if _b85chars is None: + _b85chars = [bytes((i,)) for i in _b85alphabet] + _b85chars2 = [(a + b) for a in _b85chars for b in _b85chars] + return _85encode(b, _b85chars, _b85chars2, pad) + +def b85decode(b): + """Decode base85-encoded byte array""" + global _b85dec + # Delay the initialization of tables to not waste memory + # if the function is never called + if _b85dec is None: + _b85dec = [None] * 256 + for i, c in enumerate(_b85alphabet): + _b85dec[c] = i + + b = _bytes_from_decode_data(b) + padding = (-len(b)) % 5 + b = b + b'~' * padding + out = [] + packI = struct.Struct('!I').pack + for i in range(0, len(b), 5): + chunk = b[i:i + 5] + acc = 0 + try: + for c in chunk: + acc = acc * 85 + _b85dec[c] + except TypeError: + for j, c in enumerate(chunk): + if _b85dec[c] is None: + raise ValueError('bad base85 character at position %d' + % (i + j)) from None + raise + try: + out.append(packI(acc)) + except struct.error: + raise ValueError('base85 overflow in hunk starting at byte %d' + % i) from None + + result = b''.join(out) + if padding: + result = result[:-padding] + return result # Legacy interface. This code could be cleaned up since I don't believe # binascii has any line length limitations. It just doesn't seem worth it @@ -335,12 +514,26 @@ def decode(input, output): s = binascii.a2b_base64(line) output.write(s) +def _input_type_check(s): + try: + m = memoryview(s) + except TypeError as err: + msg = "expected bytes-like object, not %s" % s.__class__.__name__ + raise TypeError(msg) from err + if m.format not in ('c', 'b', 'B'): + msg = ("expected single byte elements, not %r from %s" % + (m.format, s.__class__.__name__)) + raise TypeError(msg) + if m.ndim != 1: + msg = ("expected 1-D data, not %d-D data from %s" % + (m.ndim, s.__class__.__name__)) + raise TypeError(msg) + def encodebytes(s): """Encode a bytestring into a bytestring containing multiple lines of base-64 data.""" - if not isinstance(s, bytes_types): - raise TypeError("expected bytes, not %s" % s.__class__.__name__) + _input_type_check(s) pieces = [] for i in range(0, len(s), MAXBINSIZE): chunk = s[i : i + MAXBINSIZE] @@ -357,8 +550,7 @@ def encodestring(s): def decodebytes(s): """Decode a bytestring of base-64 data into a bytestring.""" - if not isinstance(s, bytes_types): - raise TypeError("expected bytes, not %s" % s.__class__.__name__) + _input_type_check(s) return binascii.a2b_base64(s) def decodestring(s): |