def safe_decode_hdr(msg=None, name=None, hdr=None, charset=None):
"""
This method stubbornly tries to decode header data and convert
to Pythonic unicode strings. The strings are guaranteed not to
contain tab, newline or carriage return characters.
If used with a message object, the header and the MIME charset
will be inferred from the message headers.
>>> msg = email.message.Message()
>>> msg['content-type'] = 'text/plain; charset=utf-8'
>>> msg['from'] = 'G\\xc3\\xadsli R \\xc3\\x93la <*****@*****.**>'
>>> safe_decode_hdr(msg, 'from')
u'G\\xedsli R \\xd3la <*****@*****.**>'
The =?...?= MIME header encoding is also recognized and processed.
>>> safe_decode_hdr(hdr='=?iso-8859-1?Q?G=EDsli_R_=D3la?=\\r\\n<*****@*****.**>')
u'G\\xedsli R \\xd3la <*****@*****.**>'
>>> safe_decode_hdr(hdr='"=?utf-8?Q?G=EDsli_R?= =?iso-8859-1?Q?=D3la?="')
u'G\\xedsli R \\xd3la'
And finally, guesses are made with raw binary data. This process
could be improved, it currently only attempts utf-8 and iso-8859-1.
>>> safe_decode_hdr(hdr='"G\\xedsli R \\xd3la"\\r\\t<*****@*****.**>')
u'"G\\xedsli R \\xd3la" <*****@*****.**>'
>>> safe_decode_hdr(hdr='"G\\xc3\\xadsli R \\xc3\\x93la"\\n <*****@*****.**>')
u'"G\\xedsli R \\xd3la" <*****@*****.**>'
# See https://bugs.python.org/issue1079
# encoded word enclosed in parenthesis (comment syntax)
>>> safe_decode_hdr(hdr='[email protected] (=?utf-8?Q?Ren=C3=A9?=)')
u'[email protected] ( Ren\\xe9 )'
# no space after encoded word
>>> safe_decode_hdr(hdr='=?UTF-8?Q?Direction?=<*****@*****.**>')
u'Direction <*****@*****.**>'
"""
if hdr is None:
value = msg and msg[name] or ''
charset = charset or msg.get_content_charset() or 'utf-8'
else:
value = hdr
charset = charset or 'utf-8'
if not isinstance(value, unicode):
# Already a str! Oh shit, might be nasty binary data.
value = try_decode(value, charset, replace='?')
# At this point we know we have a unicode string. Next we try
# to very stubbornly decode and discover character sets.
if '=?' in value and '?=' in value:
try:
# decode_header wants an unquoted str (not unicode)
value = value.encode('utf-8').replace('"', '')
# Decode!
pairs = decode_header(value)
value = ' '.join([try_decode(t, cs or charset)
for t, cs in pairs])
except email.errors.HeaderParseError:
pass
# Finally, return the unicode data, with white-space normalized
return value.replace('\r', ' ').replace('\t', ' ').replace('\n', ' ')
def test_decode_header_no_encoding(self):
res = decode_header("olmsted")
self.assertEqual(res, [('olmsted', None)])
