remail/mail: Handle dwmw2s magic evo plugin

dwmw2's evolution plugin which seems to workaround ms-exchange oddities has
another interesting format not handled by remail yet:

multipart/mixed with:
  - empty text/plain section
  - application/pgp-encrypted
  - application/octed-stream

Check for this with at least some sanity checks and morph it into a regular
multipart/encrypted message so decrypt can handle it without adding more
mess to that part.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner 2020-03-11 11:57:42 +01:00
parent 76c07f6d49
commit 7e4cace1e2

View file

@ -402,6 +402,56 @@ def msg_sanitize_outlook(msg):
# code. # code.
continue continue
def msg_handle_multimix(msg):
'''
Magic format used by dwmw2's devolution plugin to prevent
exchange from wreckaging mail. It's kinda valid, but sigh...
Multipart mixed message with:
- empty text/plain
- application/pgp-encrypted
- application/octed-stream
Make it look like a sane PGP application/encrypted mail
'''
ct = msg.get_content_type()
if ct != 'multipart/mixed':
return
fnames = ['msg.asc', 'encrypted.asc']
gpgpl = 0
otherpl = []
payloads = msg.get_payload()
for payload in payloads:
try:
ct = payload.get_content_type()
print(ct)
if ct == 'application/pgp-encrypted':
gpgpl += 1
continue
elif ct == 'application/octet-stream':
fname = payload.get_filename(None)
if gpgpl == 1 and fname in fnames:
gpgpl += 1
continue
# None of the above. Mark it as other
otherpl.append(payload)
except:
# Ignore fails here. This is all best effort
# guesswork.
pass
if gpgpl != 2:
return
# Remove the irrelevant payload parts
for pl in otherpl:
payloads.remove(pl)
# Fixup the message type so decrypt knows what to do with it
msg.set_type('multipart/encrypted')
msg.set_param('protocol', 'application/pgp-encrypted')
def decode_base64(msg): def decode_base64(msg):
# #
# Decode base64 encoded text/plain sections # Decode base64 encoded text/plain sections
@ -436,6 +486,9 @@ def msg_sanitize_incoming(msg):
# Strip html multipart first # Strip html multipart first
msg_strip_html(msg) msg_strip_html(msg)
# Handle multipart/mixed
msg_handle_multimix(msg)
# Sanitize outlook crappola # Sanitize outlook crappola
msg_sanitize_outlook(msg) msg_sanitize_outlook(msg)