Rework PGP-Inline verification/recognition

lacre/core.py

@@ -285,7 +285,7 @@ def _encrypt_all_payloads_inline(message, gpg_to_cmdline):
     return encrypted_payloads
 
 
-def _encrypt_all_payloads_mime(message, gpg_to_cmdline):
+def _encrypt_all_payloads_mime(message: email.message.Message, gpg_to_cmdline):
     # Convert a plain text email into PGP/MIME attachment style.  Modeled after enigmail.
     pgp_ver_part = email.message.Message()
     pgp_ver_part.set_payload("Version: 1"+text.EOL)
@@ -308,7 +308,7 @@ def _encrypt_all_payloads_mime(message, gpg_to_cmdline):
         encoding = sys.getdefaultencoding()
         if 'Content-Type' in message and not message['Content-Type'].startswith('multipart'):
             additionalSubHeader = "Content-Type: " + message['Content-Type'] + text.EOL
-            (base, encoding) = text.parse_content_type(message['Content-Type'])
+            encoding = message.get_content_charset(sys.getdefaultencoding())
             LOG.debug(f"Identified encoding as {encoding}")
         encrypted_part.set_payload(additionalSubHeader+text.EOL + message.get_payload(decode=True).decode(encoding))
         check_nested = True
@@ -335,7 +335,7 @@ def _encrypt_all_payloads_mime(message, gpg_to_cmdline):
 
 def _encrypt_payload(payload, gpg_to_cmdline, check_nested=True):
     raw_payload = payload.get_payload(decode=True)
-    if check_nested and text.is_pgp_inline(raw_payload):
+    if check_nested and text.is_payload_pgp_inline(raw_payload):
         LOG.debug("Message is already pgp encrypted. No nested encryption needed.")
         return payload
 
@@ -492,7 +492,7 @@ def send_msg(message: str, recipients, fromaddr=None):
         LOG.info("No recipient found")
 
 
-def _is_encrypted(raw_message):
+def _is_encrypted(raw_message: email.message.Message):
     if raw_message.get_content_type() == 'multipart/encrypted':
         return True
 
@@ -500,12 +500,14 @@ def _is_encrypted(raw_message):
     if first_part.get_content_type() == 'application/pkcs7-mime':
         return True
 
-    first_payload = first_part.get_payload(decode=True)
-    return text.is_pgp_inline(first_payload)
+    return text.is_message_pgp_inline(first_part)
 
 
-def delivery_plan(recipients, key_cache: kcache.KeyCache):
+def delivery_plan(recipients, message: email.message.Message, key_cache: kcache.KeyCache):
     """Generate a sequence of delivery strategies."""
+    if _is_encrypted(message):
+        return [KeepIntact(recipients)]
+
     gpg_to, ungpg_to = _identify_gpg_recipients(recipients, key_cache)
 
     gpg_mime_to, gpg_mime_cmd, gpg_inline_to, gpg_inline_cmd = \
@@ -531,7 +533,8 @@ def deliver_message(raw_message: email.message.Message, from_address, to_addrs):
     # Ugly workaround to keep the code working without too many changes.
     from_addr = from_address
 
-    recipients_left = [text.sanitize_case_sense(recipient) for recipient in to_addrs]
+    sanitize = text.choose_sanitizer(conf.get_item('default', 'mail_case_insensitive'))
+    recipients_left = [sanitize(recipient) for recipient in to_addrs]
 
     # There is no need for nested encryption
     LOG.debug("Seeing if it's already encrypted")

lacre/daemon.py

@@ -16,7 +16,6 @@ from watchdog.observers import Observer
 # These are the only values that our mail handler is allowed to return.
 RESULT_OK = '250 OK'
 RESULT_ERROR = '500 Could not process your message'
-RESULT_NOT_IMPLEMENTED = '500 Not implemented yet'
 
 # Load configuration and init logging, in this order.  Only then can we load
 # the last Lacre module, i.e. lacre.mailgate.
@@ -41,7 +40,7 @@ class MailEncryptionProxy:
         try:
             keys = await self._keyring.freeze_identities()
             message = email.message_from_bytes(envelope.content)
-            for operation in gate.delivery_plan(envelope.rcpt_tos, keys):
+            for operation in gate.delivery_plan(envelope.rcpt_tos, message, keys):
                 LOG.debug(f"Sending mail via {operation!r}")
                 new_message = operation.perform(message)
                 gate.send_msg(new_message, operation.recipients(), envelope.mail_from)

lacre/keyring.py

@@ -5,6 +5,7 @@ module.
 """
 
 import lacre.text as text
+import lacre.config as conf
 import logging
 from os import stat
 from watchdog.events import FileSystemEventHandler
@@ -17,7 +18,8 @@ LOG = logging.getLogger(__name__)
 
 
 def _sanitize(keys):
-    return {fingerprint: text.sanitize_case_sense(keys[fingerprint]) for fingerprint in keys}
+    sanitize = text.choose_sanitizer(conf.get_item('default', 'mail_case_insensitive'))
+    return {fingerprint: sanitize(keys[fingerprint]) for fingerprint in keys}
 
 
 class KeyCacheMisconfiguration(Exception):

lacre/text.py

@@ -1,8 +1,10 @@
+"""Basic payload-processing routines."""
+
 import sys
 import re
 import logging
+from email.message import Message
 
-import lacre.config as conf
 
 # The standard way to encode line-ending in email:
 EOL = "\r\n"
@@ -14,7 +16,7 @@ PGP_INLINE_END = b"-----END PGP MESSAGE-----"
 LOG = logging.getLogger(__name__)
 
 
-def parse_content_type(content_type):
+def parse_content_type(content_type: str):
     """Analyse Content-Type email header.
 
     Return a pair: type and sub-type.
@@ -49,19 +51,36 @@ def parse_delimiter(address: str):
         return (address, None)
 
 
-def sanitize_case_sense(address):
-    """Sanitize email case."""
-    # TODO: find a way to make it more unit-testable
-    if conf.flag_enabled('default', 'mail_case_insensitive'):
-        address = address.lower()
+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:
-        splitted_address = address.split('@')
-        if len(splitted_address) > 1:
-            address = splitted_address[0] + '@' + splitted_address[1].lower()
-
-    return address
+        return address
 
 
-def is_pgp_inline(payload) -> bool:
-    """Find out if the payload (bytes) contains PGP/INLINE markers."""
+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))