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Diffstat (limited to 'modules/language/python/module/base64.py')
| -rwxr-xr-x | modules/language/python/module/base64.py | 598 |
1 files changed, 598 insertions, 0 deletions
diff --git a/modules/language/python/module/base64.py b/modules/language/python/module/base64.py new file mode 100755 index 0000000..a61cdbe --- /dev/null +++ b/modules/language/python/module/base64.py @@ -0,0 +1,598 @@ +module(base64) + +"""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 +# Modified 22-May-2007 by Guido van Rossum to use bytes everywhere + +import re +import struct +import binascii + + +__all__ = [ + # Legacy interface exports traditional RFC 2045 Base64 encodings + 'encode', 'decode', 'encodebytes', 'decodebytes', + # 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 + # starting at: + # + # http://zgp.org/pipermail/p2p-hackers/2001-September/000316.html + 'urlsafe_b64encode', 'urlsafe_b64decode', + ] + + +bytes_types = (bytes, bytearray) # Types acceptable as binary data + +def _bytes_from_decode_data(s): + if isinstance(s, str): + try: + return s.encode('ascii') + except UnicodeEncodeError: + raise ValueError('string argument should contain only ASCII characters') + if isinstance(s, bytes_types): + return s + 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 + +def b64encode(s, altchars=None): + """Encode the bytes-like object s using Base64 and return a bytes object. + + Optional altchars should be a byte string of length 2 which specifies an + alternative alphabet for the '+' and '/' characters. This allows an + application to e.g. generate url or filesystem safe Base64 strings. + """ + encoded = binascii.b2a_base64(s, newline=False) + if altchars is not None: + assert len(altchars) == 2, repr(altchars) + return encoded.translate(bytes.maketrans(b'+/', altchars)) + return encoded + + +def b64decode(s, altchars=None, validate=False): + """Decode the Base64 encoded bytes-like object or ASCII string s. + + Optional altchars must be a bytes-like object or ASCII string of length 2 + which specifies the alternative alphabet used instead of the '+' and '/' + characters. + + The result is returned as a bytes object. A binascii.Error is raised if + s is incorrectly padded. + + If validate is False (the default), characters that are neither in the + normal base-64 alphabet nor the alternative alphabet are discarded prior + to the padding check. If validate is True, these non-alphabet characters + in the input result in a binascii.Error. + """ + s = _bytes_from_decode_data(s) + if altchars is not None: + altchars = _bytes_from_decode_data(altchars) + assert len(altchars) == 2, repr(altchars) + s = s.translate(bytes.maketrans(altchars, b'+/')) + if validate and not re.match(b'^[A-Za-z0-9+/]*={0,2}$', s): + raise binascii.Error('Non-base64 digit found') + return binascii.a2b_base64(s) + + +def standard_b64encode(s): + """Encode bytes-like object s using the standard Base64 alphabet. + + The result is returned as a bytes object. + """ + return b64encode(s) + +def standard_b64decode(s): + """Decode bytes encoded with the standard Base64 alphabet. + + Argument s is a bytes-like object or ASCII string to decode. The result + is returned as a bytes object. A binascii.Error is raised if the input + is incorrectly padded. Characters that are not in the standard alphabet + are discarded prior to the padding check. + """ + return b64decode(s) + + +_urlsafe_encode_translation = bytes.maketrans(b'+/', b'-_') +_urlsafe_decode_translation = bytes.maketrans(b'-_', b'+/') + +def urlsafe_b64encode(s): + """Encode bytes using the URL- and filesystem-safe Base64 alphabet. + + Argument s is a bytes-like object to encode. The result is returned as a + bytes object. The alphabet uses '-' instead of '+' and '_' instead of + '/'. + """ + return b64encode(s).translate(_urlsafe_encode_translation) + +def urlsafe_b64decode(s): + """Decode bytes using the URL- and filesystem-safe Base64 alphabet. + + Argument s is a bytes-like object or ASCII string to decode. The result + is returned as a bytes object. A binascii.Error is raised if the input + is incorrectly padded. Characters that are not in the URL-safe base-64 + alphabet, and are not a plus '+' or slash '/', are discarded prior to the + padding check. + + The alphabet uses '-' instead of '+' and '_' instead of '/'. + """ + s = _bytes_from_decode_data(s) + s = s.translate(_urlsafe_decode_translation) + return b64decode(s) + + + +# Base32 encoding/decoding must be done in Python +_b32alphabet = b'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567' +_b32tab2 = None +_b32rev = None + +def b32encode(s): + """Encode the bytes-like object s using Base32 and return a bytes object. + """ + 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): + s = memoryview(s).tobytes() + leftover = len(s) % 5 + # Pad the last quantum with zero bits if necessary + if leftover: + s = s + b'\0' * (5 - leftover) # Don't use += ! + encoded = bytearray() + 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'======' + elif leftover == 2: + encoded[-4:] = b'====' + elif leftover == 3: + encoded[-3:] = b'===' + elif leftover == 4: + encoded[-1:] = b'=' + return bytes(encoded) + +def b32decode(s, casefold=False, map01=None): + """Decode the Base32 encoded bytes-like object or ASCII string s. + + Optional casefold is a flag specifying whether a lowercase alphabet is + acceptable as input. For security purposes, the default is False. + + RFC 3548 allows for optional mapping of the digit 0 (zero) to the + letter O (oh), and for optional mapping of the digit 1 (one) to + either the letter I (eye) or letter L (el). The optional argument + map01 when not None, specifies which letter the digit 1 should be + mapped to (when map01 is not None, the digit 0 is always mapped to + the letter O). For security purposes the default is None, so that + 0 and 1 are not allowed in the input. + + The result is returned as a bytes object. A binascii.Error is raised if + 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) + 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 + # either L (el) or I (eye). + if map01 is not None: + map01 = _bytes_from_decode_data(map01) + assert len(map01) == 1, repr(map01) + s = s.translate(bytes.maketrans(b'01', b'O' + map01)) + if casefold: + s = s.upper() + # 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. + l = len(s) + s = s.rstrip(b'=') + padchars = l - len(s) + # Now decode the full quanta + 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 + 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) + + + +# RFC 3548, Base 16 Alphabet specifies uppercase, but hexlify() returns +# lowercase. The RFC also recommends against accepting input case +# insensitively. +def b16encode(s): + """Encode the bytes-like object s using Base16 and return a bytes object. + """ + return binascii.hexlify(s).upper() + + +def b16decode(s, casefold=False): + """Decode the Base16 encoded bytes-like object or ASCII string s. + + Optional casefold is a flag specifying whether a lowercase alphabet is + acceptable as input. For security purposes, the default is False. + + The result is returned as a bytes object. A binascii.Error is raised if + s is incorrectly padded or if there are non-alphabet characters present + in the input. + """ + s = _bytes_from_decode_data(s) + if casefold: + s = s.upper() + if re.search(b'[^0-9A-F]', s): + 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 bytes-like object b using Ascii85 and return a bytes object. + + 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 (b'\\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 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 the Ascii85 encoded bytes-like object or ASCII string b. + + 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. + + The result is returned as a bytes object. + """ + b = _bytes_from_decode_data(b) + if adobe: + if not b.endswith(_A85END): + raise ValueError( + "Ascii85 encoded byte sequences must end " + "with {!r}".format(_A85END) + ) + if b.startswith(_A85START): + b = b[2:-2] # Strip off start/end markers + else: + b = b[:-2] + # + # 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 bytes-like object b in base85 format and return a bytes object. + + If pad is true, the input is padded with b'\\0' so its length is a multiple of + 4 bytes 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 the base85-encoded bytes-like object or ASCII string b + + The result is returned as a bytes object. + """ + 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 +# though. The files should be opened in binary mode. + +MAXLINESIZE = 76 # Excluding the CRLF +MAXBINSIZE = (MAXLINESIZE//4)*3 + +def encode(input, output): + """Encode a file; input and output are binary files.""" + while True: + s = input.read(MAXBINSIZE) + if not s: + break + while len(s) < MAXBINSIZE: + ns = input.read(MAXBINSIZE-len(s)) + if not ns: + break + s += ns + line = binascii.b2a_base64(s) + output.write(line) + + +def decode(input, output): + """Decode a file; input and output are binary files.""" + while True: + line = input.readline() + if not line: + break + 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 bytes object containing multiple lines + of base-64 data.""" + _input_type_check(s) + pieces = [] + for i in range(0, len(s), MAXBINSIZE): + chunk = s[i : i + MAXBINSIZE] + pieces.append(binascii.b2a_base64(chunk)) + return b"".join(pieces) + +def encodestring(s): + """Legacy alias of encodebytes().""" + import warnings + warnings.warn("encodestring() is a deprecated alias since 3.1, " + "use encodebytes()", + DeprecationWarning, 2) + return encodebytes(s) + + +def decodebytes(s): + """Decode a bytestring of base-64 data into a bytes object.""" + _input_type_check(s) + return binascii.a2b_base64(s) + +def decodestring(s): + """Legacy alias of decodebytes().""" + import warnings + warnings.warn("decodestring() is a deprecated alias since Python 3.1, " + "use decodebytes()", + DeprecationWarning, 2) + return decodebytes(s) + + +# Usable as a script... +def main(): + """Small main program""" + import sys, getopt + try: + opts, args = getopt.getopt(sys.argv[1:], 'deut') + except getopt.error as msg: + sys.stdout = sys.stderr + print(msg) + print("""usage: %s [-d|-e|-u|-t] [file|-] + -d, -u: decode + -e: encode (default) + -t: encode and decode string 'Aladdin:open sesame'"""%sys.argv[0]) + sys.exit(2) + func = encode + for o, a in opts: + if o == '-e': func = encode + if o == '-d': func = decode + if o == '-u': func = decode + if o == '-t': test(); return + if args and args[0] != '-': + with open(args[0], 'rb') as f: + func(f, sys.stdout.buffer) + else: + func(sys.stdin.buffer, sys.stdout.buffer) + + +def test(): + s0 = b"Aladdin:open sesame" + print(repr(s0)) + s1 = encodebytes(s0) + print(repr(s1)) + s2 = decodebytes(s1) + print(repr(s2)) + assert s0 == s2 |