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planemo upload commit 2e9511a184a1ca667c7be0c6321a36dc4e3d116d
author jpayne
date Tue, 18 Mar 2025 17:55:14 -0400
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67:0e9998148a16 69:33d812a61356
1 # Copyright (C) 2001-2007 Python Software Foundation
2 # Author: Ben Gertzfield, Barry Warsaw
3 # Contact: email-sig@python.org
4
5 __all__ = [
6 'Charset',
7 'add_alias',
8 'add_charset',
9 'add_codec',
10 ]
11
12 from functools import partial
13
14 import email.base64mime
15 import email.quoprimime
16
17 from email import errors
18 from email.encoders import encode_7or8bit
19
20
21
22 # Flags for types of header encodings
23 QP = 1 # Quoted-Printable
24 BASE64 = 2 # Base64
25 SHORTEST = 3 # the shorter of QP and base64, but only for headers
26
27 # In "=?charset?q?hello_world?=", the =?, ?q?, and ?= add up to 7
28 RFC2047_CHROME_LEN = 7
29
30 DEFAULT_CHARSET = 'us-ascii'
31 UNKNOWN8BIT = 'unknown-8bit'
32 EMPTYSTRING = ''
33
34
35
36 # Defaults
37 CHARSETS = {
38 # input header enc body enc output conv
39 'iso-8859-1': (QP, QP, None),
40 'iso-8859-2': (QP, QP, None),
41 'iso-8859-3': (QP, QP, None),
42 'iso-8859-4': (QP, QP, None),
43 # iso-8859-5 is Cyrillic, and not especially used
44 # iso-8859-6 is Arabic, also not particularly used
45 # iso-8859-7 is Greek, QP will not make it readable
46 # iso-8859-8 is Hebrew, QP will not make it readable
47 'iso-8859-9': (QP, QP, None),
48 'iso-8859-10': (QP, QP, None),
49 # iso-8859-11 is Thai, QP will not make it readable
50 'iso-8859-13': (QP, QP, None),
51 'iso-8859-14': (QP, QP, None),
52 'iso-8859-15': (QP, QP, None),
53 'iso-8859-16': (QP, QP, None),
54 'windows-1252':(QP, QP, None),
55 'viscii': (QP, QP, None),
56 'us-ascii': (None, None, None),
57 'big5': (BASE64, BASE64, None),
58 'gb2312': (BASE64, BASE64, None),
59 'euc-jp': (BASE64, None, 'iso-2022-jp'),
60 'shift_jis': (BASE64, None, 'iso-2022-jp'),
61 'iso-2022-jp': (BASE64, None, None),
62 'koi8-r': (BASE64, BASE64, None),
63 'utf-8': (SHORTEST, BASE64, 'utf-8'),
64 }
65
66 # Aliases for other commonly-used names for character sets. Map
67 # them to the real ones used in email.
68 ALIASES = {
69 'latin_1': 'iso-8859-1',
70 'latin-1': 'iso-8859-1',
71 'latin_2': 'iso-8859-2',
72 'latin-2': 'iso-8859-2',
73 'latin_3': 'iso-8859-3',
74 'latin-3': 'iso-8859-3',
75 'latin_4': 'iso-8859-4',
76 'latin-4': 'iso-8859-4',
77 'latin_5': 'iso-8859-9',
78 'latin-5': 'iso-8859-9',
79 'latin_6': 'iso-8859-10',
80 'latin-6': 'iso-8859-10',
81 'latin_7': 'iso-8859-13',
82 'latin-7': 'iso-8859-13',
83 'latin_8': 'iso-8859-14',
84 'latin-8': 'iso-8859-14',
85 'latin_9': 'iso-8859-15',
86 'latin-9': 'iso-8859-15',
87 'latin_10':'iso-8859-16',
88 'latin-10':'iso-8859-16',
89 'cp949': 'ks_c_5601-1987',
90 'euc_jp': 'euc-jp',
91 'euc_kr': 'euc-kr',
92 'ascii': 'us-ascii',
93 }
94
95
96 # Map charsets to their Unicode codec strings.
97 CODEC_MAP = {
98 'gb2312': 'eucgb2312_cn',
99 'big5': 'big5_tw',
100 # Hack: We don't want *any* conversion for stuff marked us-ascii, as all
101 # sorts of garbage might be sent to us in the guise of 7-bit us-ascii.
102 # Let that stuff pass through without conversion to/from Unicode.
103 'us-ascii': None,
104 }
105
106
107
108 # Convenience functions for extending the above mappings
109 def add_charset(charset, header_enc=None, body_enc=None, output_charset=None):
110 """Add character set properties to the global registry.
111
112 charset is the input character set, and must be the canonical name of a
113 character set.
114
115 Optional header_enc and body_enc is either Charset.QP for
116 quoted-printable, Charset.BASE64 for base64 encoding, Charset.SHORTEST for
117 the shortest of qp or base64 encoding, or None for no encoding. SHORTEST
118 is only valid for header_enc. It describes how message headers and
119 message bodies in the input charset are to be encoded. Default is no
120 encoding.
121
122 Optional output_charset is the character set that the output should be
123 in. Conversions will proceed from input charset, to Unicode, to the
124 output charset when the method Charset.convert() is called. The default
125 is to output in the same character set as the input.
126
127 Both input_charset and output_charset must have Unicode codec entries in
128 the module's charset-to-codec mapping; use add_codec(charset, codecname)
129 to add codecs the module does not know about. See the codecs module's
130 documentation for more information.
131 """
132 if body_enc == SHORTEST:
133 raise ValueError('SHORTEST not allowed for body_enc')
134 CHARSETS[charset] = (header_enc, body_enc, output_charset)
135
136
137 def add_alias(alias, canonical):
138 """Add a character set alias.
139
140 alias is the alias name, e.g. latin-1
141 canonical is the character set's canonical name, e.g. iso-8859-1
142 """
143 ALIASES[alias] = canonical
144
145
146 def add_codec(charset, codecname):
147 """Add a codec that map characters in the given charset to/from Unicode.
148
149 charset is the canonical name of a character set. codecname is the name
150 of a Python codec, as appropriate for the second argument to the unicode()
151 built-in, or to the encode() method of a Unicode string.
152 """
153 CODEC_MAP[charset] = codecname
154
155
156
157 # Convenience function for encoding strings, taking into account
158 # that they might be unknown-8bit (ie: have surrogate-escaped bytes)
159 def _encode(string, codec):
160 if codec == UNKNOWN8BIT:
161 return string.encode('ascii', 'surrogateescape')
162 else:
163 return string.encode(codec)
164
165
166
167 class Charset:
168 """Map character sets to their email properties.
169
170 This class provides information about the requirements imposed on email
171 for a specific character set. It also provides convenience routines for
172 converting between character sets, given the availability of the
173 applicable codecs. Given a character set, it will do its best to provide
174 information on how to use that character set in an email in an
175 RFC-compliant way.
176
177 Certain character sets must be encoded with quoted-printable or base64
178 when used in email headers or bodies. Certain character sets must be
179 converted outright, and are not allowed in email. Instances of this
180 module expose the following information about a character set:
181
182 input_charset: The initial character set specified. Common aliases
183 are converted to their `official' email names (e.g. latin_1
184 is converted to iso-8859-1). Defaults to 7-bit us-ascii.
185
186 header_encoding: If the character set must be encoded before it can be
187 used in an email header, this attribute will be set to
188 Charset.QP (for quoted-printable), Charset.BASE64 (for
189 base64 encoding), or Charset.SHORTEST for the shortest of
190 QP or BASE64 encoding. Otherwise, it will be None.
191
192 body_encoding: Same as header_encoding, but describes the encoding for the
193 mail message's body, which indeed may be different than the
194 header encoding. Charset.SHORTEST is not allowed for
195 body_encoding.
196
197 output_charset: Some character sets must be converted before they can be
198 used in email headers or bodies. If the input_charset is
199 one of them, this attribute will contain the name of the
200 charset output will be converted to. Otherwise, it will
201 be None.
202
203 input_codec: The name of the Python codec used to convert the
204 input_charset to Unicode. If no conversion codec is
205 necessary, this attribute will be None.
206
207 output_codec: The name of the Python codec used to convert Unicode
208 to the output_charset. If no conversion codec is necessary,
209 this attribute will have the same value as the input_codec.
210 """
211 def __init__(self, input_charset=DEFAULT_CHARSET):
212 # RFC 2046, $4.1.2 says charsets are not case sensitive. We coerce to
213 # unicode because its .lower() is locale insensitive. If the argument
214 # is already a unicode, we leave it at that, but ensure that the
215 # charset is ASCII, as the standard (RFC XXX) requires.
216 try:
217 if isinstance(input_charset, str):
218 input_charset.encode('ascii')
219 else:
220 input_charset = str(input_charset, 'ascii')
221 except UnicodeError:
222 raise errors.CharsetError(input_charset)
223 input_charset = input_charset.lower()
224 # Set the input charset after filtering through the aliases
225 self.input_charset = ALIASES.get(input_charset, input_charset)
226 # We can try to guess which encoding and conversion to use by the
227 # charset_map dictionary. Try that first, but let the user override
228 # it.
229 henc, benc, conv = CHARSETS.get(self.input_charset,
230 (SHORTEST, BASE64, None))
231 if not conv:
232 conv = self.input_charset
233 # Set the attributes, allowing the arguments to override the default.
234 self.header_encoding = henc
235 self.body_encoding = benc
236 self.output_charset = ALIASES.get(conv, conv)
237 # Now set the codecs. If one isn't defined for input_charset,
238 # guess and try a Unicode codec with the same name as input_codec.
239 self.input_codec = CODEC_MAP.get(self.input_charset,
240 self.input_charset)
241 self.output_codec = CODEC_MAP.get(self.output_charset,
242 self.output_charset)
243
244 def __repr__(self):
245 return self.input_charset.lower()
246
247 def __eq__(self, other):
248 return str(self) == str(other).lower()
249
250 def get_body_encoding(self):
251 """Return the content-transfer-encoding used for body encoding.
252
253 This is either the string `quoted-printable' or `base64' depending on
254 the encoding used, or it is a function in which case you should call
255 the function with a single argument, the Message object being
256 encoded. The function should then set the Content-Transfer-Encoding
257 header itself to whatever is appropriate.
258
259 Returns "quoted-printable" if self.body_encoding is QP.
260 Returns "base64" if self.body_encoding is BASE64.
261 Returns conversion function otherwise.
262 """
263 assert self.body_encoding != SHORTEST
264 if self.body_encoding == QP:
265 return 'quoted-printable'
266 elif self.body_encoding == BASE64:
267 return 'base64'
268 else:
269 return encode_7or8bit
270
271 def get_output_charset(self):
272 """Return the output character set.
273
274 This is self.output_charset if that is not None, otherwise it is
275 self.input_charset.
276 """
277 return self.output_charset or self.input_charset
278
279 def header_encode(self, string):
280 """Header-encode a string by converting it first to bytes.
281
282 The type of encoding (base64 or quoted-printable) will be based on
283 this charset's `header_encoding`.
284
285 :param string: A unicode string for the header. It must be possible
286 to encode this string to bytes using the character set's
287 output codec.
288 :return: The encoded string, with RFC 2047 chrome.
289 """
290 codec = self.output_codec or 'us-ascii'
291 header_bytes = _encode(string, codec)
292 # 7bit/8bit encodings return the string unchanged (modulo conversions)
293 encoder_module = self._get_encoder(header_bytes)
294 if encoder_module is None:
295 return string
296 return encoder_module.header_encode(header_bytes, codec)
297
298 def header_encode_lines(self, string, maxlengths):
299 """Header-encode a string by converting it first to bytes.
300
301 This is similar to `header_encode()` except that the string is fit
302 into maximum line lengths as given by the argument.
303
304 :param string: A unicode string for the header. It must be possible
305 to encode this string to bytes using the character set's
306 output codec.
307 :param maxlengths: Maximum line length iterator. Each element
308 returned from this iterator will provide the next maximum line
309 length. This parameter is used as an argument to built-in next()
310 and should never be exhausted. The maximum line lengths should
311 not count the RFC 2047 chrome. These line lengths are only a
312 hint; the splitter does the best it can.
313 :return: Lines of encoded strings, each with RFC 2047 chrome.
314 """
315 # See which encoding we should use.
316 codec = self.output_codec or 'us-ascii'
317 header_bytes = _encode(string, codec)
318 encoder_module = self._get_encoder(header_bytes)
319 encoder = partial(encoder_module.header_encode, charset=codec)
320 # Calculate the number of characters that the RFC 2047 chrome will
321 # contribute to each line.
322 charset = self.get_output_charset()
323 extra = len(charset) + RFC2047_CHROME_LEN
324 # Now comes the hard part. We must encode bytes but we can't split on
325 # bytes because some character sets are variable length and each
326 # encoded word must stand on its own. So the problem is you have to
327 # encode to bytes to figure out this word's length, but you must split
328 # on characters. This causes two problems: first, we don't know how
329 # many octets a specific substring of unicode characters will get
330 # encoded to, and second, we don't know how many ASCII characters
331 # those octets will get encoded to. Unless we try it. Which seems
332 # inefficient. In the interest of being correct rather than fast (and
333 # in the hope that there will be few encoded headers in any such
334 # message), brute force it. :(
335 lines = []
336 current_line = []
337 maxlen = next(maxlengths) - extra
338 for character in string:
339 current_line.append(character)
340 this_line = EMPTYSTRING.join(current_line)
341 length = encoder_module.header_length(_encode(this_line, charset))
342 if length > maxlen:
343 # This last character doesn't fit so pop it off.
344 current_line.pop()
345 # Does nothing fit on the first line?
346 if not lines and not current_line:
347 lines.append(None)
348 else:
349 separator = (' ' if lines else '')
350 joined_line = EMPTYSTRING.join(current_line)
351 header_bytes = _encode(joined_line, codec)
352 lines.append(encoder(header_bytes))
353 current_line = [character]
354 maxlen = next(maxlengths) - extra
355 joined_line = EMPTYSTRING.join(current_line)
356 header_bytes = _encode(joined_line, codec)
357 lines.append(encoder(header_bytes))
358 return lines
359
360 def _get_encoder(self, header_bytes):
361 if self.header_encoding == BASE64:
362 return email.base64mime
363 elif self.header_encoding == QP:
364 return email.quoprimime
365 elif self.header_encoding == SHORTEST:
366 len64 = email.base64mime.header_length(header_bytes)
367 lenqp = email.quoprimime.header_length(header_bytes)
368 if len64 < lenqp:
369 return email.base64mime
370 else:
371 return email.quoprimime
372 else:
373 return None
374
375 def body_encode(self, string):
376 """Body-encode a string by converting it first to bytes.
377
378 The type of encoding (base64 or quoted-printable) will be based on
379 self.body_encoding. If body_encoding is None, we assume the
380 output charset is a 7bit encoding, so re-encoding the decoded
381 string using the ascii codec produces the correct string version
382 of the content.
383 """
384 if not string:
385 return string
386 if self.body_encoding is BASE64:
387 if isinstance(string, str):
388 string = string.encode(self.output_charset)
389 return email.base64mime.body_encode(string)
390 elif self.body_encoding is QP:
391 # quopromime.body_encode takes a string, but operates on it as if
392 # it were a list of byte codes. For a (minimal) history on why
393 # this is so, see changeset 0cf700464177. To correctly encode a
394 # character set, then, we must turn it into pseudo bytes via the
395 # latin1 charset, which will encode any byte as a single code point
396 # between 0 and 255, which is what body_encode is expecting.
397 if isinstance(string, str):
398 string = string.encode(self.output_charset)
399 string = string.decode('latin1')
400 return email.quoprimime.body_encode(string)
401 else:
402 if isinstance(string, str):
403 string = string.encode(self.output_charset).decode('ascii')
404 return string