407 lines
17 KiB
Python
407 lines
17 KiB
Python
|
# Copyright (C) 2001-2007 Python Software Foundation
|
|||
|
|
# Author: Ben Gertzfield, Barry Warsaw
|
|||
|
|
# Contact: email-sig@python.org
|
|||
|
|
|
|||
|
|
__all__ = [
|
|||
|
|
'Charset',
|
|||
|
|
'add_alias',
|
|||
|
|
'add_charset',
|
|||
|
|
'add_codec',
|
|||
|
|
]
|
|||
|
|
|
|||
|
|
from functools import partial
|
|||
|
|
|
|||
|
|
import email.base64mime
|
|||
|
|
import email.quoprimime
|
|||
|
|
|
|||
|
|
from email import errors
|
|||
|
|
from email.encoders import encode_7or8bit
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
# Flags for types of header encodings
|
|||
|
|
QP = 1 # Quoted-Printable
|
|||
|
|
BASE64 = 2 # Base64
|
|||
|
|
SHORTEST = 3 # the shorter of QP and base64, but only for headers
|
|||
|
|
|
|||
|
|
# In "=?charset?q?hello_world?=", the =?, ?q?, and ?= add up to 7
|
|||
|
|
RFC2047_CHROME_LEN = 7
|
|||
|
|
|
|||
|
|
DEFAULT_CHARSET = 'us-ascii'
|
|||
|
|
UNKNOWN8BIT = 'unknown-8bit'
|
|||
|
|
EMPTYSTRING = ''
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
# Defaults
|
|||
|
|
CHARSETS = {
|
|||
|
|
# input header enc body enc output conv
|
|||
|
|
'iso-8859-1': (QP, QP, None),
|
|||
|
|
'iso-8859-2': (QP, QP, None),
|
|||
|
|
'iso-8859-3': (QP, QP, None),
|
|||
|
|
'iso-8859-4': (QP, QP, None),
|
|||
|
|
# iso-8859-5 is Cyrillic, and not especially used
|
|||
|
|
# iso-8859-6 is Arabic, also not particularly used
|
|||
|
|
# iso-8859-7 is Greek, QP will not make it readable
|
|||
|
|
# iso-8859-8 is Hebrew, QP will not make it readable
|
|||
|
|
'iso-8859-9': (QP, QP, None),
|
|||
|
|
'iso-8859-10': (QP, QP, None),
|
|||
|
|
# iso-8859-11 is Thai, QP will not make it readable
|
|||
|
|
'iso-8859-13': (QP, QP, None),
|
|||
|
|
'iso-8859-14': (QP, QP, None),
|
|||
|
|
'iso-8859-15': (QP, QP, None),
|
|||
|
|
'iso-8859-16': (QP, QP, None),
|
|||
|
|
'windows-1252':(QP, QP, None),
|
|||
|
|
'viscii': (QP, QP, None),
|
|||
|
|
'us-ascii': (None, None, None),
|
|||
|
|
'big5': (BASE64, BASE64, None),
|
|||
|
|
'gb2312': (BASE64, BASE64, None),
|
|||
|
|
'euc-jp': (BASE64, None, 'iso-2022-jp'),
|
|||
|
|
'shift_jis': (BASE64, None, 'iso-2022-jp'),
|
|||
|
|
'iso-2022-jp': (BASE64, None, None),
|
|||
|
|
'koi8-r': (BASE64, BASE64, None),
|
|||
|
|
'utf-8': (SHORTEST, BASE64, 'utf-8'),
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
# Aliases for other commonly-used names for character sets. Map
|
|||
|
|
# them to the real ones used in email.
|
|||
|
|
ALIASES = {
|
|||
|
|
'latin_1': 'iso-8859-1',
|
|||
|
|
'latin-1': 'iso-8859-1',
|
|||
|
|
'latin_2': 'iso-8859-2',
|
|||
|
|
'latin-2': 'iso-8859-2',
|
|||
|
|
'latin_3': 'iso-8859-3',
|
|||
|
|
'latin-3': 'iso-8859-3',
|
|||
|
|
'latin_4': 'iso-8859-4',
|
|||
|
|
'latin-4': 'iso-8859-4',
|
|||
|
|
'latin_5': 'iso-8859-9',
|
|||
|
|
'latin-5': 'iso-8859-9',
|
|||
|
|
'latin_6': 'iso-8859-10',
|
|||
|
|
'latin-6': 'iso-8859-10',
|
|||
|
|
'latin_7': 'iso-8859-13',
|
|||
|
|
'latin-7': 'iso-8859-13',
|
|||
|
|
'latin_8': 'iso-8859-14',
|
|||
|
|
'latin-8': 'iso-8859-14',
|
|||
|
|
'latin_9': 'iso-8859-15',
|
|||
|
|
'latin-9': 'iso-8859-15',
|
|||
|
|
'latin_10':'iso-8859-16',
|
|||
|
|
'latin-10':'iso-8859-16',
|
|||
|
|
'cp949': 'ks_c_5601-1987',
|
|||
|
|
'euc_jp': 'euc-jp',
|
|||
|
|
'euc_kr': 'euc-kr',
|
|||
|
|
'ascii': 'us-ascii',
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
|
|||
|
|
# Map charsets to their Unicode codec strings.
|
|||
|
|
CODEC_MAP = {
|
|||
|
|
'gb2312': 'eucgb2312_cn',
|
|||
|
|
'big5': 'big5_tw',
|
|||
|
|
# Hack: We don't want *any* conversion for stuff marked us-ascii, as all
|
|||
|
|
# sorts of garbage might be sent to us in the guise of 7-bit us-ascii.
|
|||
|
|
# Let that stuff pass through without conversion to/from Unicode.
|
|||
|
|
'us-ascii': None,
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
# Convenience functions for extending the above mappings
|
|||
|
|
def add_charset(charset, header_enc=None, body_enc=None, output_charset=None):
|
|||
|
|
"""Add character set properties to the global registry.
|
|||
|
|
|
|||
|
|
charset is the input character set, and must be the canonical name of a
|
|||
|
|
character set.
|
|||
|
|
|
|||
|
|
Optional header_enc and body_enc is either Charset.QP for
|
|||
|
|
quoted-printable, Charset.BASE64 for base64 encoding, Charset.SHORTEST for
|
|||
|
|
the shortest of qp or base64 encoding, or None for no encoding. SHORTEST
|
|||
|
|
is only valid for header_enc. It describes how message headers and
|
|||
|
|
message bodies in the input charset are to be encoded. Default is no
|
|||
|
|
encoding.
|
|||
|
|
|
|||
|
|
Optional output_charset is the character set that the output should be
|
|||
|
|
in. Conversions will proceed from input charset, to Unicode, to the
|
|||
|
|
output charset when the method Charset.convert() is called. The default
|
|||
|
|
is to output in the same character set as the input.
|
|||
|
|
|
|||
|
|
Both input_charset and output_charset must have Unicode codec entries in
|
|||
|
|
the module's charset-to-codec mapping; use add_codec(charset, codecname)
|
|||
|
|
to add codecs the module does not know about. See the codecs module's
|
|||
|
|
documentation for more information.
|
|||
|
|
"""
|
|||
|
|
if body_enc == SHORTEST:
|
|||
|
|
raise ValueError('SHORTEST not allowed for body_enc')
|
|||
|
|
CHARSETS[charset] = (header_enc, body_enc, output_charset)
|
|||
|
|
|
|||
|
|
|
|||
|
|
def add_alias(alias, canonical):
|
|||
|
|
"""Add a character set alias.
|
|||
|
|
|
|||
|
|
alias is the alias name, e.g. latin-1
|
|||
|
|
canonical is the character set's canonical name, e.g. iso-8859-1
|
|||
|
|
"""
|
|||
|
|
ALIASES[alias] = canonical
|
|||
|
|
|
|||
|
|
|
|||
|
|
def add_codec(charset, codecname):
|
|||
|
|
"""Add a codec that map characters in the given charset to/from Unicode.
|
|||
|
|
|
|||
|
|
charset is the canonical name of a character set. codecname is the name
|
|||
|
|
of a Python codec, as appropriate for the second argument to the unicode()
|
|||
|
|
built-in, or to the encode() method of a Unicode string.
|
|||
|
|
"""
|
|||
|
|
CODEC_MAP[charset] = codecname
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
# Convenience function for encoding strings, taking into account
|
|||
|
|
# that they might be unknown-8bit (ie: have surrogate-escaped bytes)
|
|||
|
|
def _encode(string, codec):
|
|||
|
|
if codec == UNKNOWN8BIT:
|
|||
|
|
return string.encode('ascii', 'surrogateescape')
|
|||
|
|
else:
|
|||
|
|
return string.encode(codec)
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
class Charset:
|
|||
|
|
"""Map character sets to their email properties.
|
|||
|
|
|
|||
|
|
This class provides information about the requirements imposed on email
|
|||
|
|
for a specific character set. It also provides convenience routines for
|
|||
|
|
converting between character sets, given the availability of the
|
|||
|
|
applicable codecs. Given a character set, it will do its best to provide
|
|||
|
|
information on how to use that character set in an email in an
|
|||
|
|
RFC-compliant way.
|
|||
|
|
|
|||
|
|
Certain character sets must be encoded with quoted-printable or base64
|
|||
|
|
when used in email headers or bodies. Certain character sets must be
|
|||
|
|
converted outright, and are not allowed in email. Instances of this
|
|||
|
|
module expose the following information about a character set:
|
|||
|
|
|
|||
|
|
input_charset: The initial character set specified. Common aliases
|
|||
|
|
are converted to their `official' email names (e.g. latin_1
|
|||
|
|
is converted to iso-8859-1). Defaults to 7-bit us-ascii.
|
|||
|
|
|
|||
|
|
header_encoding: If the character set must be encoded before it can be
|
|||
|
|
used in an email header, this attribute will be set to
|
|||
|
|
Charset.QP (for quoted-printable), Charset.BASE64 (for
|
|||
|
|
base64 encoding), or Charset.SHORTEST for the shortest of
|
|||
|
|
QP or BASE64 encoding. Otherwise, it will be None.
|
|||
|
|
|
|||
|
|
body_encoding: Same as header_encoding, but describes the encoding for the
|
|||
|
|
mail message's body, which indeed may be different than the
|
|||
|
|
header encoding. Charset.SHORTEST is not allowed for
|
|||
|
|
body_encoding.
|
|||
|
|
|
|||
|
|
output_charset: Some character sets must be converted before they can be
|
|||
|
|
used in email headers or bodies. If the input_charset is
|
|||
|
|
one of them, this attribute will contain the name of the
|
|||
|
|
charset output will be converted to. Otherwise, it will
|
|||
|
|
be None.
|
|||
|
|
|
|||
|
|
input_codec: The name of the Python codec used to convert the
|
|||
|
|
input_charset to Unicode. If no conversion codec is
|
|||
|
|
necessary, this attribute will be None.
|
|||
|
|
|
|||
|
|
output_codec: The name of the Python codec used to convert Unicode
|
|||
|
|
to the output_charset. If no conversion codec is necessary,
|
|||
|
|
this attribute will have the same value as the input_codec.
|
|||
|
|
"""
|
|||
|
|
def __init__(self, input_charset=DEFAULT_CHARSET):
|
|||
|
|
# RFC 2046, $4.1.2 says charsets are not case sensitive. We coerce to
|
|||
|
|
# unicode because its .lower() is locale insensitive. If the argument
|
|||
|
|
# is already a unicode, we leave it at that, but ensure that the
|
|||
|
|
# charset is ASCII, as the standard (RFC XXX) requires.
|
|||
|
|
try:
|
|||
|
|
if isinstance(input_charset, str):
|
|||
|
|
input_charset.encode('ascii')
|
|||
|
|
else:
|
|||
|
|
input_charset = str(input_charset, 'ascii')
|
|||
|
|
except UnicodeError:
|
|||
|
|
raise errors.CharsetError(input_charset)
|
|||
|
|
input_charset = input_charset.lower()
|
|||
|
|
# Set the input charset after filtering through the aliases
|
|||
|
|
self.input_charset = ALIASES.get(input_charset, input_charset)
|
|||
|
|
# We can try to guess which encoding and conversion to use by the
|
|||
|
|
# charset_map dictionary. Try that first, but let the user override
|
|||
|
|
# it.
|
|||
|
|
henc, benc, conv = CHARSETS.get(self.input_charset,
|
|||
|
|
(SHORTEST, BASE64, None))
|
|||
|
|
if not conv:
|
|||
|
|
conv = self.input_charset
|
|||
|
|
# Set the attributes, allowing the arguments to override the default.
|
|||
|
|
self.header_encoding = henc
|
|||
|
|
self.body_encoding = benc
|
|||
|
|
self.output_charset = ALIASES.get(conv, conv)
|
|||
|
|
# Now set the codecs. If one isn't defined for input_charset,
|
|||
|
|
# guess and try a Unicode codec with the same name as input_codec.
|
|||
|
|
self.input_codec = CODEC_MAP.get(self.input_charset,
|
|||
|
|
self.input_charset)
|
|||
|
|
self.output_codec = CODEC_MAP.get(self.output_charset,
|
|||
|
|
self.output_charset)
|
|||
|
|
|
|||
|
|
def __str__(self):
|
|||
|
|
return self.input_charset.lower()
|
|||
|
|
|
|||
|
|
__repr__ = __str__
|
|||
|
|
|
|||
|
|
def __eq__(self, other):
|
|||
|
|
return str(self) == str(other).lower()
|
|||
|
|
|
|||
|
|
def get_body_encoding(self):
|
|||
|
|
"""Return the content-transfer-encoding used for body encoding.
|
|||
|
|
|
|||
|
|
This is either the string `quoted-printable' or `base64' depending on
|
|||
|
|
the encoding used, or it is a function in which case you should call
|
|||
|
|
the function with a single argument, the Message object being
|
|||
|
|
encoded. The function should then set the Content-Transfer-Encoding
|
|||
|
|
header itself to whatever is appropriate.
|
|||
|
|
|
|||
|
|
Returns "quoted-printable" if self.body_encoding is QP.
|
|||
|
|
Returns "base64" if self.body_encoding is BASE64.
|
|||
|
|
Returns conversion function otherwise.
|
|||
|
|
"""
|
|||
|
|
assert self.body_encoding != SHORTEST
|
|||
|
|
if self.body_encoding == QP:
|
|||
|
|
return 'quoted-printable'
|
|||
|
|
elif self.body_encoding == BASE64:
|
|||
|
|
return 'base64'
|
|||
|
|
else:
|
|||
|
|
return encode_7or8bit
|
|||
|
|
|
|||
|
|
def get_output_charset(self):
|
|||
|
|
"""Return the output character set.
|
|||
|
|
|
|||
|
|
This is self.output_charset if that is not None, otherwise it is
|
|||
|
|
self.input_charset.
|
|||
|
|
"""
|
|||
|
|
return self.output_charset or self.input_charset
|
|||
|
|
|
|||
|
|
def header_encode(self, string):
|
|||
|
|
"""Header-encode a string by converting it first to bytes.
|
|||
|
|
|
|||
|
|
The type of encoding (base64 or quoted-printable) will be based on
|
|||
|
|
this charset's `header_encoding`.
|
|||
|
|
|
|||
|
|
:param string: A unicode string for the header. It must be possible
|
|||
|
|
to encode this string to bytes using the character set's
|
|||
|
|
output codec.
|
|||
|
|
:return: The encoded string, with RFC 2047 chrome.
|
|||
|
|
"""
|
|||
|
|
codec = self.output_codec or 'us-ascii'
|
|||
|
|
header_bytes = _encode(string, codec)
|
|||
|
|
# 7bit/8bit encodings return the string unchanged (modulo conversions)
|
|||
|
|
encoder_module = self._get_encoder(header_bytes)
|
|||
|
|
if encoder_module is None:
|
|||
|
|
return string
|
|||
|
|
return encoder_module.header_encode(header_bytes, codec)
|
|||
|
|
|
|||
|
|
def header_encode_lines(self, string, maxlengths):
|
|||
|
|
"""Header-encode a string by converting it first to bytes.
|
|||
|
|
|
|||
|
|
This is similar to `header_encode()` except that the string is fit
|
|||
|
|
into maximum line lengths as given by the argument.
|
|||
|
|
|
|||
|
|
:param string: A unicode string for the header. It must be possible
|
|||
|
|
to encode this string to bytes using the character set's
|
|||
|
|
output codec.
|
|||
|
|
:param maxlengths: Maximum line length iterator. Each element
|
|||
|
|
returned from this iterator will provide the next maximum line
|
|||
|
|
length. This parameter is used as an argument to built-in next()
|
|||
|
|
and should never be exhausted. The maximum line lengths should
|
|||
|
|
not count the RFC 2047 chrome. These line lengths are only a
|
|||
|
|
hint; the splitter does the best it can.
|
|||
|
|
:return: Lines of encoded strings, each with RFC 2047 chrome.
|
|||
|
|
"""
|
|||
|
|
# See which encoding we should use.
|
|||
|
|
codec = self.output_codec or 'us-ascii'
|
|||
|
|
header_bytes = _encode(string, codec)
|
|||
|
|
encoder_module = self._get_encoder(header_bytes)
|
|||
|
|
encoder = partial(encoder_module.header_encode, charset=codec)
|
|||
|
|
# Calculate the number of characters that the RFC 2047 chrome will
|
|||
|
|
# contribute to each line.
|
|||
|
|
charset = self.get_output_charset()
|
|||
|
|
extra = len(charset) + RFC2047_CHROME_LEN
|
|||
|
|
# Now comes the hard part. We must encode bytes but we can't split on
|
|||
|
|
# bytes because some character sets are variable length and each
|
|||
|
|
# encoded word must stand on its own. So the problem is you have to
|
|||
|
|
# encode to bytes to figure out this word's length, but you must split
|
|||
|
|
# on characters. This causes two problems: first, we don't know how
|
|||
|
|
# many octets a specific substring of unicode characters will get
|
|||
|
|
# encoded to, and second, we don't know how many ASCII characters
|
|||
|
|
# those octets will get encoded to. Unless we try it. Which seems
|
|||
|
|
# inefficient. In the interest of being correct rather than fast (and
|
|||
|
|
# in the hope that there will be few encoded headers in any such
|
|||
|
|
# message), brute force it. :(
|
|||
|
|
lines = []
|
|||
|
|
current_line = []
|
|||
|
|
maxlen = next(maxlengths) - extra
|
|||
|
|
for character in string:
|
|||
|
|
current_line.append(character)
|
|||
|
|
this_line = EMPTYSTRING.join(current_line)
|
|||
|
|
length = encoder_module.header_length(_encode(this_line, charset))
|
|||
|
|
if length > maxlen:
|
|||
|
|
# This last character doesn't fit so pop it off.
|
|||
|
|
current_line.pop()
|
|||
|
|
# Does nothing fit on the first line?
|
|||
|
|
if not lines and not current_line:
|
|||
|
|
lines.append(None)
|
|||
|
|
else:
|
|||
|
|
separator = (' ' if lines else '')
|
|||
|
|
joined_line = EMPTYSTRING.join(current_line)
|
|||
|
|
header_bytes = _encode(joined_line, codec)
|
|||
|
|
lines.append(encoder(header_bytes))
|
|||
|
|
current_line = [character]
|
|||
|
|
maxlen = next(maxlengths) - extra
|
|||
|
|
joined_line = EMPTYSTRING.join(current_line)
|
|||
|
|
header_bytes = _encode(joined_line, codec)
|
|||
|
|
lines.append(encoder(header_bytes))
|
|||
|
|
return lines
|
|||
|
|
|
|||
|
|
def _get_encoder(self, header_bytes):
|
|||
|
|
if self.header_encoding == BASE64:
|
|||
|
|
return email.base64mime
|
|||
|
|
elif self.header_encoding == QP:
|
|||
|
|
return email.quoprimime
|
|||
|
|
elif self.header_encoding == SHORTEST:
|
|||
|
|
len64 = email.base64mime.header_length(header_bytes)
|
|||
|
|
lenqp = email.quoprimime.header_length(header_bytes)
|
|||
|
|
if len64 < lenqp:
|
|||
|
|
return email.base64mime
|
|||
|
|
else:
|
|||
|
|
return email.quoprimime
|
|||
|
|
else:
|
|||
|
|
return None
|
|||
|
|
|
|||
|
|
def body_encode(self, string):
|
|||
|
|
"""Body-encode a string by converting it first to bytes.
|
|||
|
|
|
|||
|
|
The type of encoding (base64 or quoted-printable) will be based on
|
|||
|
|
self.body_encoding. If body_encoding is None, we assume the
|
|||
|
|
output charset is a 7bit encoding, so re-encoding the decoded
|
|||
|
|
string using the ascii codec produces the correct string version
|
|||
|
|
of the content.
|
|||
|
|
"""
|
|||
|
|
if not string:
|
|||
|
|
return string
|
|||
|
|
if self.body_encoding is BASE64:
|
|||
|
|
if isinstance(string, str):
|
|||
|
|
string = string.encode(self.output_charset)
|
|||
|
|
return email.base64mime.body_encode(string)
|
|||
|
|
elif self.body_encoding is QP:
|
|||
|
|
# quopromime.body_encode takes a string, but operates on it as if
|
|||
|
|
# it were a list of byte codes. For a (minimal) history on why
|
|||
|
|
# this is so, see changeset 0cf700464177. To correctly encode a
|
|||
|
|
# character set, then, we must turn it into pseudo bytes via the
|
|||
|
|
# latin1 charset, which will encode any byte as a single code point
|
|||
|
|
# between 0 and 255, which is what body_encode is expecting.
|
|||
|
|
if isinstance(string, str):
|
|||
|
|
string = string.encode(self.output_charset)
|
|||
|
|
string = string.decode('latin1')
|
|||
|
|
return email.quoprimime.body_encode(string)
|
|||
|
|
else:
|
|||
|
|
if isinstance(string, str):
|
|||
|
|
string = string.encode(self.output_charset).decode('ascii')
|
|||
|
|
return string
|