Rework encryption exception handling

Also: remove misleading comment about message.defects.

GnuPG/__init__.py

@@ -47,24 +47,22 @@ RX_CONFIRM = re.compile(br'key "([^"]+)" imported')
 class EncryptionException(Exception):
     """Represents a failure to encrypt a payload."""
 
-    def __init__(self, issue: str, recipient: str, cause: str):
-        """Initialise an exception."""
-        self._issue = issue
-        self._recipient = recipient
-        self._cause = cause
-
     def __str__(self):
         """Return human-readable string representation."""
+        recipient, issue, cause, key = self.args
         parts = []
 
-        if self._recipient:
-            parts.append('To: ' + self._recipient)
+        if recipient:
+            parts.append('To: ' + recipient)
 
-        if self._issue:
-            parts.append('Issue: ' + self._issue)
+        if issue:
+            parts.append('Issue: ' + issue)
 
-        if self._cause:
-            parts.append('Cause: ' + self._cause)
+        if key:
+            parts.append('Key: ' + key.decode())
+
+        if cause:
+            parts.append('Cause: ' + cause)
 
         return '; '.join(parts)
 
@@ -243,7 +241,7 @@ class GPGEncryptor:
         if p.returncode != 0:
             LOG.debug('Errors: %s', err)
             details = parse_status(err)
-            raise EncryptionException(details['issue'], details['recipient'], details['cause'])
+            raise EncryptionException(details['issue'], details['recipient'], details['cause'], details['key'])
         return (encdata, p.returncode)
 
     def _popen(self):

lacre/daemon.py

@@ -42,10 +42,6 @@ class MailEncryptionProxy:
                 LOG.debug('Parsed into %s: %s', type(message), repr(message))
 
                 if message.defects:
-                    # Sometimes a weird message cannot be encoded back and
-                    # delivered, so before bouncing such messages we at least
-                    # record information about the issues.  Defects are identified
-                    # by email.* package.
                     LOG.warning("Issues found: %d; %s", len(message.defects), repr(message.defects))
 
                 if conf.flag_enabled('daemon', 'log_headers'):
@@ -63,7 +59,8 @@ class MailEncryptionProxy:
                         if not isinstance(operation, KeepIntact):
                             self._send_unencrypted(operation, message, envelope, send)
                         else:
-                            LOG.error(f'Cannot perform {operation}')
+                            LOG.error('Cannot perform: %s', operation)
+                            raise e
 
             except:
                 LOG.exception('Unexpected exception caught, bouncing message')

test/modules/test_gnupg.py

@@ -65,6 +65,10 @@ class GnuPGUtilitiesTest(unittest.TestCase):
         uid = GnuPG._parse_uid_line(sample_in)
         self.assertEqual(uid, 'alice@disposlab')
 
+    def test_exception_formatting(self):
+        e = GnuPG.EncryptionException('alice@disposlab', 'key expired', None, b'DEADBEEF')
+        self.assertEqual(str(e), 'To: alice@disposlab; Issue: key expired; Key: DEADBEEF')
+
     def test_parse_statusfd_key_expired(self):
         key_expired = b"""
 [GNUPG:] KEYEXPIRED 1668272263
@@ -74,9 +78,9 @@ class GnuPGUtilitiesTest(unittest.TestCase):
 """
 
         result = GnuPG.parse_status(key_expired)
-        self.assertEqual(result['issue'], b'KEYEXPIRED')
+        self.assertEqual(result['issue'], 'key expired')
         self.assertEqual(result['recipient'], b'name@domain')
-        self.assertEqual(result['cause'], 'No specific reason given')
+        self.assertEqual(result['cause'], 'Unknown')
         self.assertEqual(result['key'], b'XXXXXXXXXXXXX')
 
     def test_parse_statusfd_key_absent(self):
@@ -88,7 +92,7 @@ class GnuPGUtilitiesTest(unittest.TestCase):
         result = GnuPG.parse_status(non_specific_errors)
         self.assertEqual(result['issue'], b'n/a')
         self.assertEqual(result['recipient'], b'name@domain')
-        self.assertEqual(result['cause'], 'No specific reason given')
+        self.assertEqual(result['cause'], 'Unknown')
         self.assertEqual(result['key'], b'n/a')