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Diffstat (limited to 'modules/language/python/module/email/quoprimime.py')
| -rw-r--r-- | modules/language/python/module/email/quoprimime.py | 300 |
1 files changed, 300 insertions, 0 deletions
diff --git a/modules/language/python/module/email/quoprimime.py b/modules/language/python/module/email/quoprimime.py new file mode 100644 index 0000000..21b6a6b --- /dev/null +++ b/modules/language/python/module/email/quoprimime.py @@ -0,0 +1,300 @@ +module(email,quoprimime) +# Copyright (C) 2001-2006 Python Software Foundation +# Author: Ben Gertzfield +# Contact: email-sig@python.org + +"""Quoted-printable content transfer encoding per RFCs 2045-2047. + +This module handles the content transfer encoding method defined in RFC 2045 +to encode US ASCII-like 8-bit data called `quoted-printable'. It is used to +safely encode text that is in a character set similar to the 7-bit US ASCII +character set, but that includes some 8-bit characters that are normally not +allowed in email bodies or headers. + +Quoted-printable is very space-inefficient for encoding binary files; use the +email.base64mime module for that instead. + +This module provides an interface to encode and decode both headers and bodies +with quoted-printable encoding. + +RFC 2045 defines a method for including character set information in an +`encoded-word' in a header. This method is commonly used for 8-bit real names +in To:/From:/Cc: etc. fields, as well as Subject: lines. + +This module does not do the line wrapping or end-of-line character +conversion necessary for proper internationalized headers; it only +does dumb encoding and decoding. To deal with the various line +wrapping issues, use the email.header module. +""" + +__all__ = [ + 'body_decode', + 'body_encode', + 'body_length', + 'decode', + 'decodestring', + 'header_decode', + 'header_encode', + 'header_length', + 'quote', + 'unquote', + ] + +import re + +from string import ascii_letters, digits, hexdigits + +CRLF = '\r\n' +NL = '\n' +EMPTYSTRING = '' + +# Build a mapping of octets to the expansion of that octet. Since we're only +# going to have 256 of these things, this isn't terribly inefficient +# space-wise. Remember that headers and bodies have different sets of safe +# characters. Initialize both maps with the full expansion, and then override +# the safe bytes with the more compact form. +_QUOPRI_MAP = ['=%02X' % c for c in range(256)] +_QUOPRI_HEADER_MAP = _QUOPRI_MAP[:] +_QUOPRI_BODY_MAP = _QUOPRI_MAP[:] + +# Safe header bytes which need no encoding. +for c in b'-!*+/' + ascii_letters.encode('ascii') + digits.encode('ascii'): + _QUOPRI_HEADER_MAP[c] = chr(c) +# Headers have one other special encoding; spaces become underscores. +_QUOPRI_HEADER_MAP[ord(' ')] = '_' + +# Safe body bytes which need no encoding. +for c in (b' !"#$%&\'()*+,-./0123456789:;<>' + b'?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`' + b'abcdefghijklmnopqrstuvwxyz{|}~\t'): + _QUOPRI_BODY_MAP[c] = chr(c) + + + +# Helpers +def header_check(octet): + """Return True if the octet should be escaped with header quopri.""" + return chr(octet) != _QUOPRI_HEADER_MAP[octet] + + +def body_check(octet): + """Return True if the octet should be escaped with body quopri.""" + return chr(octet) != _QUOPRI_BODY_MAP[octet] + + +def header_length(bytearray): + """Return a header quoted-printable encoding length. + + Note that this does not include any RFC 2047 chrome added by + `header_encode()`. + + :param bytearray: An array of bytes (a.k.a. octets). + :return: The length in bytes of the byte array when it is encoded with + quoted-printable for headers. + """ + return sum(len(_QUOPRI_HEADER_MAP[octet]) for octet in bytearray) + + +def body_length(bytearray): + """Return a body quoted-printable encoding length. + + :param bytearray: An array of bytes (a.k.a. octets). + :return: The length in bytes of the byte array when it is encoded with + quoted-printable for bodies. + """ + return sum(len(_QUOPRI_BODY_MAP[octet]) for octet in bytearray) + + +def _max_append(L, s, maxlen, extra=''): + if not isinstance(s, str): + s = chr(s) + if not L: + L.append(s.lstrip()) + elif len(L[-1]) + len(s) <= maxlen: + L[-1] += extra + s + else: + L.append(s.lstrip()) + + +def unquote(s): + """Turn a string in the form =AB to the ASCII character with value 0xab""" + return chr(int(s[1:3], 16)) + + +def quote(c): + return _QUOPRI_MAP[ord(c)] + + +def header_encode(header_bytes, charset='iso-8859-1'): + """Encode a single header line with quoted-printable (like) encoding. + + Defined in RFC 2045, this `Q' encoding is similar to quoted-printable, but + used specifically for email header fields to allow charsets with mostly 7 + bit characters (and some 8 bit) to remain more or less readable in non-RFC + 2045 aware mail clients. + + charset names the character set to use in the RFC 2046 header. It + defaults to iso-8859-1. + """ + # Return empty headers as an empty string. + if not header_bytes: + return '' + # Iterate over every byte, encoding if necessary. + encoded = header_bytes.decode('latin1').translate(_QUOPRI_HEADER_MAP) + # Now add the RFC chrome to each encoded chunk and glue the chunks + # together. + return '=?%s?q?%s?=' % (charset, encoded) + + +_QUOPRI_BODY_ENCODE_MAP = _QUOPRI_BODY_MAP[:] +for c in b'\r\n': + _QUOPRI_BODY_ENCODE_MAP[c] = chr(c) + +def body_encode(body, maxlinelen=76, eol=NL): + """Encode with quoted-printable, wrapping at maxlinelen characters. + + Each line of encoded text will end with eol, which defaults to "\\n". Set + this to "\\r\\n" if you will be using the result of this function directly + in an email. + + Each line will be wrapped at, at most, maxlinelen characters before the + eol string (maxlinelen defaults to 76 characters, the maximum value + permitted by RFC 2045). Long lines will have the 'soft line break' + quoted-printable character "=" appended to them, so the decoded text will + be identical to the original text. + + The minimum maxlinelen is 4 to have room for a quoted character ("=XX") + followed by a soft line break. Smaller values will generate a + ValueError. + + """ + + if maxlinelen < 4: + raise ValueError("maxlinelen must be at least 4") + if not body: + return body + + # quote special characters + body = body.translate(_QUOPRI_BODY_ENCODE_MAP) + + soft_break = '=' + eol + # leave space for the '=' at the end of a line + maxlinelen1 = maxlinelen - 1 + + encoded_body = [] + append = encoded_body.append + + for line in body.splitlines(): + # break up the line into pieces no longer than maxlinelen - 1 + start = 0 + laststart = len(line) - 1 - maxlinelen + while start <= laststart: + stop = start + maxlinelen1 + # make sure we don't break up an escape sequence + if line[stop - 2] == '=': + append(line[start:stop - 1]) + start = stop - 2 + elif line[stop - 1] == '=': + append(line[start:stop]) + start = stop - 1 + else: + append(line[start:stop] + '=') + start = stop + + # handle rest of line, special case if line ends in whitespace + if line and line[-1] in ' \t': + room = start - laststart + if room >= 3: + # It's a whitespace character at end-of-line, and we have room + # for the three-character quoted encoding. + q = quote(line[-1]) + elif room == 2: + # There's room for the whitespace character and a soft break. + q = line[-1] + soft_break + else: + # There's room only for a soft break. The quoted whitespace + # will be the only content on the subsequent line. + q = soft_break + quote(line[-1]) + append(line[start:-1] + q) + else: + append(line[start:]) + + # add back final newline if present + if body[-1] in CRLF: + append('') + + return eol.join(encoded_body) + + + +# BAW: I'm not sure if the intent was for the signature of this function to be +# the same as base64MIME.decode() or not... +def decode(encoded, eol=NL): + """Decode a quoted-printable string. + + Lines are separated with eol, which defaults to \\n. + """ + if not encoded: + return encoded + # BAW: see comment in encode() above. Again, we're building up the + # decoded string with string concatenation, which could be done much more + # efficiently. + decoded = '' + + for line in encoded.splitlines(): + line = line.rstrip() + if not line: + decoded += eol + continue + + i = 0 + n = len(line) + while i < n: + c = line[i] + if c != '=': + decoded += c + i += 1 + # Otherwise, c == "=". Are we at the end of the line? If so, add + # a soft line break. + elif i+1 == n: + i += 1 + continue + # Decode if in form =AB + elif i+2 < n and line[i+1] in hexdigits and line[i+2] in hexdigits: + decoded += unquote(line[i:i+3]) + i += 3 + # Otherwise, not in form =AB, pass literally + else: + decoded += c + i += 1 + + if i == n: + decoded += eol + # Special case if original string did not end with eol + if encoded[-1] not in '\r\n' and decoded.endswith(eol): + decoded = decoded[:-1] + return decoded + + +# For convenience and backwards compatibility w/ standard base64 module +body_decode = decode +decodestring = decode + + + +def _unquote_match(match): + """Turn a match in the form =AB to the ASCII character with value 0xab""" + s = match.group(0) + return unquote(s) + + +# Header decoding is done a bit differently +def header_decode(s): + """Decode a string encoded with RFC 2045 MIME header `Q' encoding. + + This function does not parse a full MIME header value encoded with + quoted-printable (like =?iso-8859-1?q?Hello_World?=) -- please use + the high level email.header class for that functionality. + """ + s = s.replace('_', ' ') + return re.sub(r'=[a-fA-F0-9]{2}', _unquote_match, s, flags=re.ASCII) |