from email import message_from_file as _message_from_file
from email.header import decode_header as _decode_header
from email.mime.text import MIMEText as _MIMEText
+from email.utils import parseaddr as _parseaddr
import mailbox as _mailbox
import re as _re
import sys as _sys
import pgp_mime as _pgp_mime
+import pgp_mime.key as _pgp_mime_key
from . import LOG as _LOG
from .email import construct_email as _construct_email
class WrongSignatureMessage (_InsecureMessage):
- def __init__(self, pgp_key=None, signatures=None, decrypted=None,
- **kwargs):
+ def __init__(self, pgp_key=None, signatures=None, fingerprints=None,
+ decrypted=None, **kwargs):
if 'error' not in kwargs:
kwargs['error'] = 'not signed by the expected key'
super(WrongSignatureMessage, self).__init__(**kwargs)
self.pgp_key = pgp_key
self.signatures = signatures
+ self.fingerprints = fingerprints
self.decrypted = decrypted
raise
return (original, message, person, subject, target)
-def _get_message_person(course, message):
- sender = message['Return-Path'] # RFC 822
+def _get_message_person(course, message, trust_admin_from=True):
+ """Get the `Person` that sent the message.
+
+ We use 'Return-Path' (envelope from) instead of the message's From
+ header, because it's more consistent and harder to fake. However,
+ there may be times when you *want* to send a message in somebody
+ elses name.
+
+ For example, if a student submitted an assignment from an
+ unexpected address, you might add that address to their entry in
+ your course config, and then bounce the message back into
+ pygrader. In this case, the From header will still be the
+ student, but the 'Return-Path' will be you. With
+ `trust_admin_from` (on by default), messages who's 'Return-Path'
+ matches a professor or TA will have their 'From' line used to find
+ the final person responsible for the message.
+
+ >>> from pygrader.model.course import Course
+ >>> from pygrader.model.person import Person
+ >>> from pgp_mime import encodedMIMEText
+
+ >>> course = Course(people=[
+ ... Person(
+ ... name='Gandalf', emails=['g@grey.edu'], groups=['professors']),
+ ... Person(name='Bilbo', emails=['bb@shire.org']),
+ ... ])
+ >>> message = encodedMIMEText('testing')
+ >>> message['Return-Path'] = '<g@grey.edu>'
+ >>> message['From'] = 'Bill <bb@shire.org>'
+ >>> message['Message-ID'] = '<123.456@home.net>'
+
+ >>> person = _get_message_person(course=course, message=message)
+ >>> print(person)
+ <Person Bilbo>
+
+ >>> person = _get_message_person(
+ ... course=course, message=message, trust_admin_from=False)
+ >>> print(person)
+ <Person Gandalf>
+ """
+ sender = message['return-path'] # RFC 822
if sender is None:
raise NoReturnPath(message)
sender = sender[1:-1] # strip wrapping '<' and '>'
raise UnregisteredAddress(message=message, address=sender)
if len(people) > 1:
raise AmbiguousAddress(message=message, address=sender, people=people)
- return people[0]
+ person = people[0]
+ if trust_admin_from and person.is_admin():
+ mid = message['message-id']
+ from_headers = message.get_all('from')
+ if len(from_headers) == 0:
+ _LOG.debug("no 'From' headers in {}".format(mid))
+ elif len(from_headers) > 1:
+ _LOG.debug("multiple 'From' headers in {}".format(mid))
+ else:
+ name,address = _parseaddr(from_headers[0])
+ people = list(course.find_people(email=address))
+ if len(people) == 0:
+ _LOG.debug("'From' address {} is unregistered".format(address))
+ if len(people) > 1:
+ _LOG.debug("'From' address {} is ambiguous".format(address))
+ _LOG.debug('message from {} treated as being from {}'.format(
+ person, people[0]))
+ person = people[0]
+ _LOG.debug('message from {}'.format(person))
+ return person
def _get_message_subject(message):
"""
for signature in signatures:
_LOG.debug(signature.dumps())
match = None
- matches = [s for s in signatures if s.fingerprint.endswith(pgp_key)]
+ fingerprints = dict((s.fingerprint, s) for s in signatures)
+ for s in signatures:
+ for key in _pgp_mime_key.lookup_keys([s.fingerprint]):
+ if key.subkeys[0].fingerprint != s.fingerprint:
+ # the signature was made with a subkey. Add the primary.
+ fingerprints[key.subkeys[0].fingerprint] = s
+ if pgp_key.startswith('0x'):
+ key_tail = pgp_key[len('0x'):]
+ else:
+ key_tail = pgp_key
+ matches = [fingerprints[f] for f in fingerprints.keys()
+ if f.endswith(key_tail)]
if len(matches) == 0:
raise WrongSignatureMessage(
message=message, pgp_key=pgp_key, signatures=signatures,
- decrypted=decrypted)
+ fingerprints=fingerprints, decrypted=decrypted)
signature = matches[0]
if not verified:
- if signature.get_summary() != 0:
+ problems = [k for k,v in signature.summary.items() if v]
+ for good in ['green', 'valid']:
+ if good in problems:
+ problems.remove(good)
+ if problems:
raise UnverifiedSignatureMessage(
message=message, signature=signature, decrypted=decrypted)
# otherwise, we may have an untrusted key. We'll count that
# prefer a submittable example assignment
assignments = [
a for a in error.course.assignments if a.submittable]
- assignments += course.assignments # but fall back to any one
+ assignments += error.course.assignments # but fall back to any one
hint = (
'Remember to use the full name for the assignment in the\n'
'subject. For example:\n'
elif isinstance(error, _UnsignedMessage):
subject = 'unsigned message {}'.format(error.message['Message-ID'])
text = (
- 'We received an email message from you without a valid\n'
- 'PGP signature.'
+ 'We received an email message from you without a PGP\n'
+ 'signature.'
)
+ elif isinstance(error, WrongSignatureMessage):
+ lines = [
+ 'We received an email message from you without a valid',
+ 'PGP signature. We were expecting a signature by',
+ '{}, but got signatures by:'.format(error.person.pgp_key),
+ ]
+ lines.extend([' {}'.format(s.fingerprint) for s in error.signatures])
+ text = '\n'.join(lines)
+ elif isinstance(error, UnverifiedSignatureMessage):
+ text = (
+ 'We received an email message from you with an unverified\n'
+ 'signature:\n\n'
+ '{}\n\n'
+ 'If this is the key you intended to use, contact your\n'
+ 'professor or TA.'
+ ).format(error.signature.dumps(prefix=' '))
elif isinstance(error, _PermissionViolationMessage):
text = (
'We received an email from you with the following subject:\n'
' * {}').format(
error.subject, '\n * '.join(error.allowed_groups))
elif isinstance(error, _InvalidMessage):
- text = subject
+ text = (
+ 'We received an email from you with the following subject:\n'
+ ' {!r}\n'
+ 'but the message was invalid:\n'
+ ' {}').format(error.subject, error)
else:
raise NotImplementedError((type(error), error))
if target is None:
projects / pygrader.git / blobdiff