encoders.py

# Copyright (C) 2001-2006 Python Software Foundation
# Author: Barry Warsaw
# Contact: email-sig@python.org

"""Encodings and related functions."""

__all__= [
"encode_7or8bit",
"encode_base64",
"encode_noop",
"encode_quopri",
]


frombase64importencodebytesas_bencode
fromquopriimportencodestringas_encodestring


def_qencode(s):
enc=_encodestring(s, quotetabs=True)
# Must encode spaces, which quopri.encodestring() doesn't do
returnenc.replace(b" ", b"=20")


defencode_base64(msg):
"""Encode the message's payload in Base64.

 Also, add an appropriate Content-Transfer-Encoding header.
 """
orig=msg.get_payload(decode=True)
encdata=str(_bencode(orig), "ascii")
msg.set_payload(encdata)
msg["Content-Transfer-Encoding"] ="base64"


defencode_quopri(msg):
"""Encode the message's payload in quoted-printable.

 Also, add an appropriate Content-Transfer-Encoding header.
 """
orig=msg.get_payload(decode=True)
encdata=_qencode(orig)
msg.set_payload(encdata)
msg["Content-Transfer-Encoding"] ="quoted-printable"


defencode_7or8bit(msg):
"""Set the Content-Transfer-Encoding header to 7bit or 8bit."""
orig=msg.get_payload(decode=True)
iforigisNone:
# There's no payload. For backwards compatibility we use 7bit
msg["Content-Transfer-Encoding"] ="7bit"
return
# We play a trick to make this go fast. If encoding/decode to ASCII
# succeeds, we know the data must be 7bit, otherwise treat it as 8bit.
try:
ifisinstance(orig, str):
orig.encode("ascii")
else:
orig.decode("ascii")
exceptUnicodeError:
charset=msg.get_charset()
output_cset=charsetandcharset.output_charset
# iso-2022-* is non-ASCII but encodes to a 7-bit representation
ifoutput_csetandoutput_cset.lower().startswith("iso-2022-"):
msg["Content-Transfer-Encoding"] ="7bit"
else:
msg["Content-Transfer-Encoding"] ="8bit"
else:
msg["Content-Transfer-Encoding"] ="7bit"


defencode_noop(msg):
"""Do nothing."""