mirror of https://github.com/morpheus65535/bazarr
327 lines
11 KiB
Python
327 lines
11 KiB
Python
# 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.
|
|
"""
|
|
from __future__ import unicode_literals
|
|
from __future__ import division
|
|
from __future__ import absolute_import
|
|
from future.builtins import bytes, chr, dict, int, range, super
|
|
|
|
__all__ = [
|
|
'body_decode',
|
|
'body_encode',
|
|
'body_length',
|
|
'decode',
|
|
'decodestring',
|
|
'header_decode',
|
|
'header_encode',
|
|
'header_length',
|
|
'quote',
|
|
'unquote',
|
|
]
|
|
|
|
import re
|
|
import io
|
|
|
|
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_HEADER_MAP = dict((c, '=%02X' % c) for c in range(256))
|
|
_QUOPRI_BODY_MAP = _QUOPRI_HEADER_MAP.copy()
|
|
|
|
# Safe header bytes which need no encoding.
|
|
for c in bytes(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 bytes(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 '=%02X' % 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 = []
|
|
for octet in header_bytes:
|
|
encoded.append(_QUOPRI_HEADER_MAP[octet])
|
|
# Now add the RFC chrome to each encoded chunk and glue the chunks
|
|
# together.
|
|
return '=?%s?q?%s?=' % (charset, EMPTYSTRING.join(encoded))
|
|
|
|
|
|
class _body_accumulator(io.StringIO):
|
|
|
|
def __init__(self, maxlinelen, eol, *args, **kw):
|
|
super().__init__(*args, **kw)
|
|
self.eol = eol
|
|
self.maxlinelen = self.room = maxlinelen
|
|
|
|
def write_str(self, s):
|
|
"""Add string s to the accumulated body."""
|
|
self.write(s)
|
|
self.room -= len(s)
|
|
|
|
def newline(self):
|
|
"""Write eol, then start new line."""
|
|
self.write_str(self.eol)
|
|
self.room = self.maxlinelen
|
|
|
|
def write_soft_break(self):
|
|
"""Write a soft break, then start a new line."""
|
|
self.write_str('=')
|
|
self.newline()
|
|
|
|
def write_wrapped(self, s, extra_room=0):
|
|
"""Add a soft line break if needed, then write s."""
|
|
if self.room < len(s) + extra_room:
|
|
self.write_soft_break()
|
|
self.write_str(s)
|
|
|
|
def write_char(self, c, is_last_char):
|
|
if not is_last_char:
|
|
# Another character follows on this line, so we must leave
|
|
# extra room, either for it or a soft break, and whitespace
|
|
# need not be quoted.
|
|
self.write_wrapped(c, extra_room=1)
|
|
elif c not in ' \t':
|
|
# For this and remaining cases, no more characters follow,
|
|
# so there is no need to reserve extra room (since a hard
|
|
# break will immediately follow).
|
|
self.write_wrapped(c)
|
|
elif self.room >= 3:
|
|
# It's a whitespace character at end-of-line, and we have room
|
|
# for the three-character quoted encoding.
|
|
self.write(quote(c))
|
|
elif self.room == 2:
|
|
# There's room for the whitespace character and a soft break.
|
|
self.write(c)
|
|
self.write_soft_break()
|
|
else:
|
|
# There's room only for a soft break. The quoted whitespace
|
|
# will be the only content on the subsequent line.
|
|
self.write_soft_break()
|
|
self.write(quote(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
|
|
|
|
# The last line may or may not end in eol, but all other lines do.
|
|
last_has_eol = (body[-1] in '\r\n')
|
|
|
|
# This accumulator will make it easier to build the encoded body.
|
|
encoded_body = _body_accumulator(maxlinelen, eol)
|
|
|
|
lines = body.splitlines()
|
|
last_line_no = len(lines) - 1
|
|
for line_no, line in enumerate(lines):
|
|
last_char_index = len(line) - 1
|
|
for i, c in enumerate(line):
|
|
if body_check(ord(c)):
|
|
c = quote(c)
|
|
encoded_body.write_char(c, i==last_char_index)
|
|
# Add an eol if input line had eol. All input lines have eol except
|
|
# possibly the last one.
|
|
if line_no < last_line_no or last_has_eol:
|
|
encoded_body.newline()
|
|
|
|
return encoded_body.getvalue()
|
|
|
|
|
|
|
|
# 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-8895-1?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, re.ASCII)
|