A mailgate for Postfix to encrypt incoming and outgoing email with S/MIME and/or OpenPGP and decrypting OpenPGP encrypted emails https://lacre.io
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
gpg-lacre/lacre/text.py

87 lines
2.5 KiB

"""Basic payload-processing routines."""
import sys
import re
import logging
from email.message import Message
# The standard way to encode line-ending in email:
EOL = "\r\n"
EOL_BYTES = b"\r\n"
PGP_INLINE_BEGIN = EOL_BYTES + b"-----BEGIN PGP MESSAGE-----" + EOL_BYTES
PGP_INLINE_END = EOL_BYTES + b"-----END PGP MESSAGE-----" + EOL_BYTES
LOG = logging.getLogger(__name__)
def parse_content_type(content_type: str):
"""Analyse Content-Type email header.
Return a pair: type and sub-type.
"""
parts = [p.strip() for p in content_type.split(';')]
if len(parts) == 1:
# No additional attributes provided. Use default encoding.
return (content_type, sys.getdefaultencoding())
# At least one attribute provided. Find out if any of them is named
# 'charset' and if so, use it.
ctype = parts[0]
encoding = [p for p in parts[1:] if p.startswith('charset=')]
if encoding:
eq_idx = encoding[0].index('=')
return (ctype, encoding[0][eq_idx+1:])
else:
return (ctype, sys.getdefaultencoding())
def parse_delimiter(address: str):
"""Parse an email with delimiter and topic.
Return destination emaili and topic as a tuple.
"""
withdelim = re.match('^([^\\+]+)\\+([^@]+)@(.*)$', address)
LOG.debug(f'Parsed email: {withdelim!r}')
if withdelim:
return (withdelim.group(1) + '@' + withdelim.group(3), withdelim.group(2))
else:
return (address, None)
def _lowercase_whole_address(address: str):
return address.lower()
def _lowercase_domain_only(address: str):
parts = address.split('@', maxsplit=2)
if len(parts) > 1:
return parts[0] + '@' + parts[1].lower()
else:
return address
def choose_sanitizer(mail_case_insensitive: bool):
"""Return a function to sanitize email case sense."""
if mail_case_insensitive:
return _lowercase_whole_address
else:
return _lowercase_domain_only
def is_payload_pgp_inline(payload: bytes) -> bool:
"""Find out if the payload (bytes) contains PGP/inline markers."""
return PGP_INLINE_BEGIN in payload and PGP_INLINE_END in payload
def is_message_pgp_inline(message: Message) -> bool:
"""Find out if a message is already PGP-Inline encrypted."""
if message.is_multipart() or isinstance(message.get_payload(), list):
# more than one payload, check each one of them
return any(is_message_pgp_inline(m.payload()) for m in message.iter_parts())
else:
# one payload, check it
return is_payload_pgp_inline(message.get_payload(decode=True))