| # Copyright (C) 2001-2006 Python Software Foundation |
| # Author: Ben Gertzfield, Barry Warsaw |
| # Contact: email-sig@python.org |
| |
| __all__ = [ |
| 'Charset', |
| 'add_alias', |
| 'add_charset', |
| 'add_codec', |
| ] |
| |
| import codecs |
| 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 |
| MISC_LEN = 7 |
| |
| DEFAULT_CHARSET = 'us-ascii' |
| |
| |
| |
| # 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'), |
| # We're making this one up to represent raw unencoded 8-bit |
| '8bit': (None, 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 |
| |
| |
| |
| 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 the 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, unicode): |
| input_charset.encode('ascii') |
| else: |
| input_charset = unicode(input_charset, 'ascii') |
| except UnicodeError: |
| raise errors.CharsetError(input_charset) |
| input_charset = input_charset.lower().encode('ascii') |
| # Set the input charset after filtering through the aliases and/or codecs |
| if not (input_charset in ALIASES or input_charset in CHARSETS): |
| try: |
| input_charset = codecs.lookup(input_charset).name |
| except LookupError: |
| pass |
| 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 __ne__(self, other): |
| return not self.__eq__(other) |
| |
| 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 "7bit" 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 convert(self, s): |
| """Convert a string from the input_codec to the output_codec.""" |
| if self.input_codec != self.output_codec: |
| return unicode(s, self.input_codec).encode(self.output_codec) |
| else: |
| return s |
| |
| def to_splittable(self, s): |
| """Convert a possibly multibyte string to a safely splittable format. |
| |
| Uses the input_codec to try and convert the string to Unicode, so it |
| can be safely split on character boundaries (even for multibyte |
| characters). |
| |
| Returns the string as-is if it isn't known how to convert it to |
| Unicode with the input_charset. |
| |
| Characters that could not be converted to Unicode will be replaced |
| with the Unicode replacement character U+FFFD. |
| """ |
| if isinstance(s, unicode) or self.input_codec is None: |
| return s |
| try: |
| return unicode(s, self.input_codec, 'replace') |
| except LookupError: |
| # Input codec not installed on system, so return the original |
| # string unchanged. |
| return s |
| |
| def from_splittable(self, ustr, to_output=True): |
| """Convert a splittable string back into an encoded string. |
| |
| Uses the proper codec to try and convert the string from Unicode back |
| into an encoded format. Return the string as-is if it is not Unicode, |
| or if it could not be converted from Unicode. |
| |
| Characters that could not be converted from Unicode will be replaced |
| with an appropriate character (usually '?'). |
| |
| If to_output is True (the default), uses output_codec to convert to an |
| encoded format. If to_output is False, uses input_codec. |
| """ |
| if to_output: |
| codec = self.output_codec |
| else: |
| codec = self.input_codec |
| if not isinstance(ustr, unicode) or codec is None: |
| return ustr |
| try: |
| return ustr.encode(codec, 'replace') |
| except LookupError: |
| # Output codec not installed |
| return ustr |
| |
| 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 encoded_header_len(self, s): |
| """Return the length of the encoded header string.""" |
| cset = self.get_output_charset() |
| # The len(s) of a 7bit encoding is len(s) |
| if self.header_encoding == BASE64: |
| return email.base64mime.base64_len(s) + len(cset) + MISC_LEN |
| elif self.header_encoding == QP: |
| return email.quoprimime.header_quopri_len(s) + len(cset) + MISC_LEN |
| elif self.header_encoding == SHORTEST: |
| lenb64 = email.base64mime.base64_len(s) |
| lenqp = email.quoprimime.header_quopri_len(s) |
| return min(lenb64, lenqp) + len(cset) + MISC_LEN |
| else: |
| return len(s) |
| |
| def header_encode(self, s, convert=False): |
| """Header-encode a string, optionally converting it to output_charset. |
| |
| If convert is True, the string will be converted from the input |
| charset to the output charset automatically. This is not useful for |
| multibyte character sets, which have line length issues (multibyte |
| characters must be split on a character, not a byte boundary); use the |
| high-level Header class to deal with these issues. convert defaults |
| to False. |
| |
| The type of encoding (base64 or quoted-printable) will be based on |
| self.header_encoding. |
| """ |
| cset = self.get_output_charset() |
| if convert: |
| s = self.convert(s) |
| # 7bit/8bit encodings return the string unchanged (modulo conversions) |
| if self.header_encoding == BASE64: |
| return email.base64mime.header_encode(s, cset) |
| elif self.header_encoding == QP: |
| return email.quoprimime.header_encode(s, cset, maxlinelen=None) |
| elif self.header_encoding == SHORTEST: |
| lenb64 = email.base64mime.base64_len(s) |
| lenqp = email.quoprimime.header_quopri_len(s) |
| if lenb64 < lenqp: |
| return email.base64mime.header_encode(s, cset) |
| else: |
| return email.quoprimime.header_encode(s, cset, maxlinelen=None) |
| else: |
| return s |
| |
| def body_encode(self, s, convert=True): |
| """Body-encode a string and convert it to output_charset. |
| |
| If convert is True (the default), the string will be converted from |
| the input charset to output charset automatically. Unlike |
| header_encode(), there are no issues with byte boundaries and |
| multibyte charsets in email bodies, so this is usually pretty safe. |
| |
| The type of encoding (base64 or quoted-printable) will be based on |
| self.body_encoding. |
| """ |
| if convert: |
| s = self.convert(s) |
| # 7bit/8bit encodings return the string unchanged (module conversions) |
| if self.body_encoding is BASE64: |
| return email.base64mime.body_encode(s) |
| elif self.body_encoding is QP: |
| return email.quoprimime.body_encode(s) |
| else: |
| return s |
