def test_extract_first_part():
"""Test the function for extracting the first part of a multipart message."""
message = b"header----first_part\n----second_part\n"
assert utils.extract_first_part(message, b"----") == b"first_part"
message = b"header----first_part\r\n----second_part\r\n"
assert utils.extract_first_part(message, b"----") == b"first_part"
def test_extract_first_part():
"""Test the function for extracting the first part of a multipart message."""
message = b'header----first_part\n----second_part\n'
assert utils.extract_first_part(message, b'----') == b'first_part'
message = b'header----first_part\r\n----second_part\r\n'
assert utils.extract_first_part(message, b'----') == b'first_part'
def parse(self, raw_content, find_message_cb):
"""Function parses the RAW AS2 MDN, verifies it and extracts the
processing status of the orginal AS2 message.
:param raw_content:
A byte string of the received HTTP headers followed by the body.
:param find_message_cb:
A callback the must returns the original Message Object. The
original message-id and original recipient AS2 ID are passed
as arguments to it.
:returns:
A two element tuple containing (status, detailed_status). The
status is a string indicating the status of the transaction. The
optional detailed_status gives additional information about the
processing status.
"""
status, detailed_status = None, None
self.payload = parse_mime(raw_content)
self.orig_message_id, orig_recipient = self.detect_mdn()
# Call the find message callback which should return a Message instance
orig_message = find_message_cb(self.orig_message_id, orig_recipient)
# Extract the headers and save it
mdn_headers = {}
for k, v in self.payload.items():
k = k.lower()
if k == 'message-id':
self.message_id = v.lstrip('<').rstrip('>')
mdn_headers[k] = v
if orig_message.receiver.mdn_digest_alg \
and self.payload.get_content_type() != 'multipart/signed':
status = 'failed/Failure'
detailed_status = 'Expected signed MDN but unsigned MDN returned'
return status, detailed_status
if self.payload.get_content_type() == 'multipart/signed':
message_boundary = ('--' + self.payload.get_boundary()).\
encode('utf-8')
# Extract the signature and the signed payload
signature = None
signature_types = [
'application/pkcs7-signature', 'application/x-pkcs7-signature'
]
for part in self.payload.walk():
if part.get_content_type() in signature_types:
signature = part.get_payload(decode=True)
elif part.get_content_type() == 'multipart/report':
self.payload = part
# Verify the message, first using raw message and if it fails
# then convert to canonical form and try again
mic_content = extract_first_part(raw_content, message_boundary)
verify_cert = orig_message.receiver.load_verify_cert()
try:
self.digest_alg = verify_message(mic_content, signature,
verify_cert)
except IntegrityError:
mic_content = canonicalize(self.payload)
self.digest_alg = verify_message(mic_content, signature,
verify_cert)
for part in self.payload.walk():
if part.get_content_type() == 'message/disposition-notification':
logger.debug('Found MDN report for message %s:\n%s' %
(orig_message.message_id, part.as_string()))
mdn = part.get_payload()[-1]
mdn_status = mdn['Disposition'].split(';').\
pop().strip().split(':')
status = mdn_status[0]
if status == 'processed':
mdn_mic = mdn.get('Received-Content-MIC', '').\
split(',')[0]
# TODO: Check MIC for all cases
if mdn_mic and orig_message.mic \
and mdn_mic != orig_message.mic.decode():
status = 'processed/warning'
detailed_status = 'Message Integrity check failed.'
else:
detailed_status = ' '.join(mdn_status[1:]).strip()
return status, detailed_status
def parse(self, raw_content, find_message_cb):
"""Function parses the RAW AS2 MDN, verifies it and extracts the
processing status of the orginal AS2 message.
:param raw_content:
A byte string of the received HTTP headers followed by the body.
:param find_message_cb:
A callback the must returns the original Message Object. The
original message-id and original recipient AS2 ID are passed
as arguments to it.
:returns:
A two element tuple containing (status, detailed_status). The
status is a string indicating the status of the transaction. The
optional detailed_status gives additional information about the
processing status.
"""
status, detailed_status = None, None
try:
self.payload = parse_mime(raw_content)
self.orig_message_id, orig_recipient = self.detect_mdn()
# Call the find message callback which should return a Message instance
orig_message = find_message_cb(self.orig_message_id,
orig_recipient)
# Extract the headers and save it
mdn_headers = {}
for k, v in self.payload.items():
k = k.lower()
if k == "message-id":
self.message_id = v.lstrip("<").rstrip(">")
mdn_headers[k] = v
if (orig_message.receiver.mdn_digest_alg
and self.payload.get_content_type() != "multipart/signed"):
status = "failed/Failure"
detailed_status = "Expected signed MDN but unsigned MDN returned"
return status, detailed_status
if self.payload.get_content_type() == "multipart/signed":
logger.debug(
f"Verifying signed MDN: \n{mime_to_bytes(self.payload)}")
message_boundary = (
"--" + self.payload.get_boundary()).encode("utf-8")
# Extract the signature and the signed payload
signature = None
signature_types = [
"application/pkcs7-signature",
"application/x-pkcs7-signature",
]
for part in self.payload.walk():
if part.get_content_type() in signature_types:
signature = part.get_payload(decode=True)
elif part.get_content_type() == "multipart/report":
self.payload = part
# Verify the message, first using raw message and if it fails
# then convert to canonical form and try again
mic_content = extract_first_part(raw_content, message_boundary)
verify_cert = orig_message.receiver.load_verify_cert()
try:
self.digest_alg = verify_message(mic_content, signature,
verify_cert)
except IntegrityError:
mic_content = canonicalize(self.payload)
self.digest_alg = verify_message(mic_content, signature,
verify_cert)
for part in self.payload.walk():
if part.get_content_type(
) == "message/disposition-notification":
logger.debug(
f"MDN report for message {orig_message.message_id}:\n{part.as_string()}"
)
mdn = part.get_payload()[-1]
mdn_status = mdn["Disposition"].split(
";").pop().strip().split(":")
status = mdn_status[0]
if status == "processed":
# Compare the original mic with the received mic
mdn_mic = mdn.get("Received-Content-MIC",
"").split(",")[0]
if (mdn_mic and orig_message.mic
and mdn_mic != orig_message.mic.decode()):
status = "processed/warning"
detailed_status = "Message Integrity check failed."
else:
detailed_status = " ".join(mdn_status[1:]).strip()
except MDNNotFound:
status = "failed/Failure"
detailed_status = "mdn-not-found"
except Exception as e: # pylint: disable=W0703
status = "failed/Failure"
detailed_status = f"Failed to parse received MDN. {e}"
logger.error(
f"Failed to parse AS2 MDN\n: {traceback.format_exc()}")
return status, detailed_status