1 # Copyright (C) 2001-2006 Python Software Foundation 2 # Author: Ben Gertzfield, Barry Warsaw 3 # Contact: email-sig (at] python.org 4 5 __all__ = [ 6 'Charset', 7 'add_alias', 8 'add_charset', 9 'add_codec', 10 ] 11 12 import codecs 13 import email.base64mime 14 import email.quoprimime 15 16 from email import errors 17 from email.encoders import encode_7or8bit 18 19 20 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 MISC_LEN = 7 29 30 DEFAULT_CHARSET = 'us-ascii' 31 32 33 35 # Defaults 36 CHARSETS = { 37 # input header enc body enc output conv 38 'iso-8859-1': (QP, QP, None), 39 'iso-8859-2': (QP, QP, None), 40 'iso-8859-3': (QP, QP, None), 41 'iso-8859-4': (QP, QP, None), 42 # iso-8859-5 is Cyrillic, and not especially used 43 # iso-8859-6 is Arabic, also not particularly used 44 # iso-8859-7 is Greek, QP will not make it readable 45 # iso-8859-8 is Hebrew, QP will not make it readable 46 'iso-8859-9': (QP, QP, None), 47 'iso-8859-10': (QP, QP, None), 48 # iso-8859-11 is Thai, QP will not make it readable 49 'iso-8859-13': (QP, QP, None), 50 'iso-8859-14': (QP, QP, None), 51 'iso-8859-15': (QP, QP, None), 52 'iso-8859-16': (QP, QP, None), 53 'windows-1252':(QP, QP, None), 54 'viscii': (QP, QP, None), 55 'us-ascii': (None, None, None), 56 'big5': (BASE64, BASE64, None), 57 'gb2312': (BASE64, BASE64, None), 58 'euc-jp': (BASE64, None, 'iso-2022-jp'), 59 'shift_jis': (BASE64, None, 'iso-2022-jp'), 60 'iso-2022-jp': (BASE64, None, None), 61 'koi8-r': (BASE64, BASE64, None), 62 'utf-8': (SHORTEST, BASE64, 'utf-8'), 63 # We're making this one up to represent raw unencoded 8-bit 64 '8bit': (None, BASE64, 'utf-8'), 65 } 66 67 # Aliases for other commonly-used names for character sets. Map 68 # them to the real ones used in email. 69 ALIASES = { 70 'latin_1': 'iso-8859-1', 71 'latin-1': 'iso-8859-1', 72 'latin_2': 'iso-8859-2', 73 'latin-2': 'iso-8859-2', 74 'latin_3': 'iso-8859-3', 75 'latin-3': 'iso-8859-3', 76 'latin_4': 'iso-8859-4', 77 'latin-4': 'iso-8859-4', 78 'latin_5': 'iso-8859-9', 79 'latin-5': 'iso-8859-9', 80 'latin_6': 'iso-8859-10', 81 'latin-6': 'iso-8859-10', 82 'latin_7': 'iso-8859-13', 83 'latin-7': 'iso-8859-13', 84 'latin_8': 'iso-8859-14', 85 'latin-8': 'iso-8859-14', 86 'latin_9': 'iso-8859-15', 87 'latin-9': 'iso-8859-15', 88 'latin_10':'iso-8859-16', 89 'latin-10':'iso-8859-16', 90 'cp949': 'ks_c_5601-1987', 91 'euc_jp': 'euc-jp', 92 'euc_kr': 'euc-kr', 93 'ascii': 'us-ascii', 94 } 95 96 97 # Map charsets to their Unicode codec strings. 98 CODEC_MAP = { 99 'gb2312': 'eucgb2312_cn', 100 'big5': 'big5_tw', 101 # Hack: We don't want *any* conversion for stuff marked us-ascii, as all 102 # sorts of garbage might be sent to us in the guise of 7-bit us-ascii. 103 # Let that stuff pass through without conversion to/from Unicode. 104 'us-ascii': None, 105 } 106 107 108 110 # Convenience functions for extending the above mappings 111 def add_charset(charset, header_enc=None, body_enc=None, output_charset=None): 112 """Add character set properties to the global registry. 113 114 charset is the input character set, and must be the canonical name of a 115 character set. 116 117 Optional header_enc and body_enc is either Charset.QP for 118 quoted-printable, Charset.BASE64 for base64 encoding, Charset.SHORTEST for 119 the shortest of qp or base64 encoding, or None for no encoding. SHORTEST 120 is only valid for header_enc. It describes how message headers and 121 message bodies in the input charset are to be encoded. Default is no 122 encoding. 123 124 Optional output_charset is the character set that the output should be 125 in. Conversions will proceed from input charset, to Unicode, to the 126 output charset when the method Charset.convert() is called. The default 127 is to output in the same character set as the input. 128 129 Both input_charset and output_charset must have Unicode codec entries in 130 the module's charset-to-codec mapping; use add_codec(charset, codecname) 131 to add codecs the module does not know about. See the codecs module's 132 documentation for more information. 133 """ 134 if body_enc == SHORTEST: 135 raise ValueError('SHORTEST not allowed for body_enc') 136 CHARSETS[charset] = (header_enc, body_enc, output_charset) 137 138 139 def add_alias(alias, canonical): 140 """Add a character set alias. 141 142 alias is the alias name, e.g. latin-1 143 canonical is the character set's canonical name, e.g. iso-8859-1 144 """ 145 ALIASES[alias] = canonical 146 147 148 def add_codec(charset, codecname): 149 """Add a codec that map characters in the given charset to/from Unicode. 150 151 charset is the canonical name of a character set. codecname is the name 152 of a Python codec, as appropriate for the second argument to the unicode() 153 built-in, or to the encode() method of a Unicode string. 154 """ 155 CODEC_MAP[charset] = codecname 156 157 158 160 class Charset: 161 """Map character sets to their email properties. 162 163 This class provides information about the requirements imposed on email 164 for a specific character set. It also provides convenience routines for 165 converting between character sets, given the availability of the 166 applicable codecs. Given a character set, it will do its best to provide 167 information on how to use that character set in an email in an 168 RFC-compliant way. 169 170 Certain character sets must be encoded with quoted-printable or base64 171 when used in email headers or bodies. Certain character sets must be 172 converted outright, and are not allowed in email. Instances of this 173 module expose the following information about a character set: 174 175 input_charset: The initial character set specified. Common aliases 176 are converted to their `official' email names (e.g. latin_1 177 is converted to iso-8859-1). Defaults to 7-bit us-ascii. 178 179 header_encoding: If the character set must be encoded before it can be 180 used in an email header, this attribute will be set to 181 Charset.QP (for quoted-printable), Charset.BASE64 (for 182 base64 encoding), or Charset.SHORTEST for the shortest of 183 QP or BASE64 encoding. Otherwise, it will be None. 184 185 body_encoding: Same as header_encoding, but describes the encoding for the 186 mail message's body, which indeed may be different than the 187 header encoding. Charset.SHORTEST is not allowed for 188 body_encoding. 189 190 output_charset: Some character sets must be converted before they can be 191 used in email headers or bodies. If the input_charset is 192 one of them, this attribute will contain the name of the 193 charset output will be converted to. Otherwise, it will 194 be None. 195 196 input_codec: The name of the Python codec used to convert the 197 input_charset to Unicode. If no conversion codec is 198 necessary, this attribute will be None. 199 200 output_codec: The name of the Python codec used to convert Unicode 201 to the output_charset. If no conversion codec is necessary, 202 this attribute will have the same value as the input_codec. 203 """ 204 def __init__(self, input_charset=DEFAULT_CHARSET): 205 # RFC 2046, $4.1.2 says charsets are not case sensitive. We coerce to 206 # unicode because its .lower() is locale insensitive. If the argument 207 # is already a unicode, we leave it at that, but ensure that the 208 # charset is ASCII, as the standard (RFC XXX) requires. 209 try: 210 if isinstance(input_charset, unicode): 211 input_charset.encode('ascii') 212 else: 213 input_charset = unicode(input_charset, 'ascii') 214 except UnicodeError: 215 raise errors.CharsetError(input_charset) 216 input_charset = input_charset.lower().encode('ascii') 217 # Set the input charset after filtering through the aliases and/or codecs 218 if not (input_charset in ALIASES or input_charset in CHARSETS): 219 try: 220 input_charset = codecs.lookup(input_charset).name 221 except LookupError: 222 pass 223 self.input_charset = ALIASES.get(input_charset, input_charset) 224 # We can try to guess which encoding and conversion to use by the 225 # charset_map dictionary. Try that first, but let the user override 226 # it. 227 henc, benc, conv = CHARSETS.get(self.input_charset, 228 (SHORTEST, BASE64, None)) 229 if not conv: 230 conv = self.input_charset 231 # Set the attributes, allowing the arguments to override the default. 232 self.header_encoding = henc 233 self.body_encoding = benc 234 self.output_charset = ALIASES.get(conv, conv) 235 # Now set the codecs. If one isn't defined for input_charset, 236 # guess and try a Unicode codec with the same name as input_codec. 237 self.input_codec = CODEC_MAP.get(self.input_charset, 238 self.input_charset) 239 self.output_codec = CODEC_MAP.get(self.output_charset, 240 self.output_charset) 241 242 def __str__(self): 243 return self.input_charset.lower() 244 245 __repr__ = __str__ 246 247 def __eq__(self, other): 248 return str(self) == str(other).lower() 249 250 def __ne__(self, other): 251 return not self.__eq__(other) 252 253 def get_body_encoding(self): 254 """Return the content-transfer-encoding used for body encoding. 255 256 This is either the string `quoted-printable' or `base64' depending on 257 the encoding used, or it is a function in which case you should call 258 the function with a single argument, the Message object being 259 encoded. The function should then set the Content-Transfer-Encoding 260 header itself to whatever is appropriate. 261 262 Returns "quoted-printable" if self.body_encoding is QP. 263 Returns "base64" if self.body_encoding is BASE64. 264 Returns "7bit" otherwise. 265 """ 266 assert self.body_encoding != SHORTEST 267 if self.body_encoding == QP: 268 return 'quoted-printable' 269 elif self.body_encoding == BASE64: 270 return 'base64' 271 else: 272 return encode_7or8bit 273 274 def convert(self, s): 275 """Convert a string from the input_codec to the output_codec.""" 276 if self.input_codec != self.output_codec: 277 return unicode(s, self.input_codec).encode(self.output_codec) 278 else: 279 return s 280 281 def to_splittable(self, s): 282 """Convert a possibly multibyte string to a safely splittable format. 283 284 Uses the input_codec to try and convert the string to Unicode, so it 285 can be safely split on character boundaries (even for multibyte 286 characters). 287 288 Returns the string as-is if it isn't known how to convert it to 289 Unicode with the input_charset. 290 291 Characters that could not be converted to Unicode will be replaced 292 with the Unicode replacement character U+FFFD. 293 """ 294 if isinstance(s, unicode) or self.input_codec is None: 295 return s 296 try: 297 return unicode(s, self.input_codec, 'replace') 298 except LookupError: 299 # Input codec not installed on system, so return the original 300 # string unchanged. 301 return s 302 303 def from_splittable(self, ustr, to_output=True): 304 """Convert a splittable string back into an encoded string. 305 306 Uses the proper codec to try and convert the string from Unicode back 307 into an encoded format. Return the string as-is if it is not Unicode, 308 or if it could not be converted from Unicode. 309 310 Characters that could not be converted from Unicode will be replaced 311 with an appropriate character (usually '?'). 312 313 If to_output is True (the default), uses output_codec to convert to an 314 encoded format. If to_output is False, uses input_codec. 315 """ 316 if to_output: 317 codec = self.output_codec 318 else: 319 codec = self.input_codec 320 if not isinstance(ustr, unicode) or codec is None: 321 return ustr 322 try: 323 return ustr.encode(codec, 'replace') 324 except LookupError: 325 # Output codec not installed 326 return ustr 327 328 def get_output_charset(self): 329 """Return the output character set. 330 331 This is self.output_charset if that is not None, otherwise it is 332 self.input_charset. 333 """ 334 return self.output_charset or self.input_charset 335 336 def encoded_header_len(self, s): 337 """Return the length of the encoded header string.""" 338 cset = self.get_output_charset() 339 # The len(s) of a 7bit encoding is len(s) 340 if self.header_encoding == BASE64: 341 return email.base64mime.base64_len(s) + len(cset) + MISC_LEN 342 elif self.header_encoding == QP: 343 return email.quoprimime.header_quopri_len(s) + len(cset) + MISC_LEN 344 elif self.header_encoding == SHORTEST: 345 lenb64 = email.base64mime.base64_len(s) 346 lenqp = email.quoprimime.header_quopri_len(s) 347 return min(lenb64, lenqp) + len(cset) + MISC_LEN 348 else: 349 return len(s) 350 351 def header_encode(self, s, convert=False): 352 """Header-encode a string, optionally converting it to output_charset. 353 354 If convert is True, the string will be converted from the input 355 charset to the output charset automatically. This is not useful for 356 multibyte character sets, which have line length issues (multibyte 357 characters must be split on a character, not a byte boundary); use the 358 high-level Header class to deal with these issues. convert defaults 359 to False. 360 361 The type of encoding (base64 or quoted-printable) will be based on 362 self.header_encoding. 363 """ 364 cset = self.get_output_charset() 365 if convert: 366 s = self.convert(s) 367 # 7bit/8bit encodings return the string unchanged (modulo conversions) 368 if self.header_encoding == BASE64: 369 return email.base64mime.header_encode(s, cset) 370 elif self.header_encoding == QP: 371 return email.quoprimime.header_encode(s, cset, maxlinelen=None) 372 elif self.header_encoding == SHORTEST: 373 lenb64 = email.base64mime.base64_len(s) 374 lenqp = email.quoprimime.header_quopri_len(s) 375 if lenb64 < lenqp: 376 return email.base64mime.header_encode(s, cset) 377 else: 378 return email.quoprimime.header_encode(s, cset, maxlinelen=None) 379 else: 380 return s 381 382 def body_encode(self, s, convert=True): 383 """Body-encode a string and convert it to output_charset. 384 385 If convert is True (the default), the string will be converted from 386 the input charset to output charset automatically. Unlike 387 header_encode(), there are no issues with byte boundaries and 388 multibyte charsets in email bodies, so this is usually pretty safe. 389 390 The type of encoding (base64 or quoted-printable) will be based on 391 self.body_encoding. 392 """ 393 if convert: 394 s = self.convert(s) 395 # 7bit/8bit encodings return the string unchanged (module conversions) 396 if self.body_encoding is BASE64: 397 return email.base64mime.body_encode(s) 398 elif self.body_encoding is QP: 399 return email.quoprimime.body_encode(s) 400 else: 401 return s 402
