1 # Copyright (C) 2001-2006 Python Software Foundation

     2 # Author: Barry Warsaw

     3 # Contact: email-sig@python.org

     4 

     5 """Encodings and related functions."""

     6 

     7 __all__ = [

     8     'encode_7or8bit',

     9     'encode_base64',

    10     'encode_noop',

    11     'encode_quopri',

    12     ]

    13 

    14 import base64

    15 

    16 from quopri import encodestring as _encodestring

    17 

    18 

    19 

    20 def _qencode(s):

    21     enc = _encodestring(s, quotetabs=True)

    22     # Must encode spaces, which quopri.encodestring() doesn't do

    23     return enc.replace(' ', '=20')

    24 

    25 

    26 def _bencode(s):

    27     # We can't quite use base64.encodestring() since it tacks on a "courtesy

    28     # newline".  Blech!

    29     if not s:

    30         return s

    31     hasnewline = (s[-1] == '\n')

    32     value = base64.encodestring(s)

    33     if not hasnewline and value[-1] == '\n':

    34         return value[:-1]

    35     return value

    36 

    37 

    38 

    39 def encode_base64(msg):

    40     """Encode the message's payload in Base64.

    41 

    42     Also, add an appropriate Content-Transfer-Encoding header.

    43     """

    44     orig = msg.get_payload()

    45     encdata = _bencode(orig)

    46     msg.set_payload(encdata)

    47     msg['Content-Transfer-Encoding'] = 'base64'

    48 

    49 

    50 

    51 def encode_quopri(msg):

    52     """Encode the message's payload in quoted-printable.

    53 

    54     Also, add an appropriate Content-Transfer-Encoding header.

    55     """

    56     orig = msg.get_payload()

    57     encdata = _qencode(orig)

    58     msg.set_payload(encdata)

    59     msg['Content-Transfer-Encoding'] = 'quoted-printable'

    60 

    61 

    62 

    63 def encode_7or8bit(msg):

    64     """Set the Content-Transfer-Encoding header to 7bit or 8bit."""

    65     orig = msg.get_payload()

    66     if orig is None:

    67         # There's no payload.  For backwards compatibility we use 7bit

    68         msg['Content-Transfer-Encoding'] = '7bit'

    69         return

    70     # We play a trick to make this go fast.  If encoding to ASCII succeeds, we

    71     # know the data must be 7bit, otherwise treat it as 8bit.

    72     try:

    73         orig.encode('ascii')

    74     except UnicodeError:

    75         # iso-2022-* is non-ASCII but still 7-bit

    76         charset = msg.get_charset()

    77         output_cset = charset and charset.output_charset

    78         if output_cset and output_cset.lower().startswith('iso-2202-'):

    79             msg['Content-Transfer-Encoding'] = '7bit'

    80         else:

    81             msg['Content-Transfer-Encoding'] = '8bit'

    82     else:

    83         msg['Content-Transfer-Encoding'] = '7bit'

    84 

    85 

    86 

    87 def encode_noop(msg):

    88     """Do nothing."""