Check mandatory config early, add tests

Also: extend failover logging configuration with file-based handler to make
sure that the user gets _some_ logs even if they do not configure Lacre at
all.

gpg-mailgate.py

@@ -41,8 +41,12 @@ from email.mime.message import MIMEMessage
 
 import logging
 import lacre
+import lacre.text as text
 import lacre.config as conf
 
+# Exit code taken from <sysexits.h>:
+EX_CONFIG = 78
+
 def gpg_encrypt( raw_message, recipients ):
 	global LOG
 
@@ -198,7 +202,7 @@ 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']+"\n"
-			(base, encoding) = parse_content_type(message['Content-Type'])
+			(base, encoding) = text.parse_content_type(message['Content-Type'])
 			LOG.debug(f"Identified encoding as {encoding}")
 		encrypted_part.set_payload(additionalSubHeader+"\n" +message.get_payload(decode=True).decode(encoding))
 		check_nested = True
@@ -222,14 +226,6 @@ def encrypt_all_payloads_mime( message, gpg_to_cmdline ):
 
 	return [ pgp_ver_part, encrypt_payload(encrypted_part, gpg_to_cmdline, check_nested) ]
 
-def parse_content_type(content_type):
-	split_at = content_type.index(';')
-	second_part = content_type[split_at+1 : ].strip()
-	if second_part.startswith('charset'):
-		return (content_type[0 : split_at], second_part[second_part.index('=') + 1 : ].strip())
-	else:
-		return (content_type[0 : split_at], sys.getdefaultencoding())
-
 def encrypt_payload( payload, gpg_to_cmdline, check_nested = True ):
 	global LOG
 
@@ -380,9 +376,6 @@ def send_msg( message, recipients ):
 
 	recipients = [_f for _f in recipients if _f]
 	if recipients:
-		if not (conf.config_item_set('relay', 'host') and conf.config_item_set('relay', 'port')):
-			LOG.warning("Missing settings for relay. Sending email aborted.")
-			return None
 		LOG.info("Sending email to: <%s>" % '> <'.join( recipients ))
 		relay = (conf.get_item('relay', 'host'), int(conf.get_item('relay', 'port')))
 		smtp = smtplib.SMTP(relay[0], relay[1])
@@ -434,9 +427,13 @@ def sort_recipients( raw_message, from_addr, to_addrs ):
 conf.load_config()
 lacre.init_logging(conf.get_item('logging', 'config'))
 
-
 LOG = logging.getLogger(__name__)
 
+missing_params = conf.validate_config()
+if missing_params:
+    LOG.error(f"Aborting delivery! Following mandatory config parameters are missing: {missing_params!r}")
+    sys.exit(EX_CONFIG)
+
 # Read e-mail from stdin
 raw = sys.stdin.read()
 raw_message = email.message_from_string( raw )

lacre/__init__.py

@@ -20,11 +20,17 @@ FAIL_OVER_LOGGING_CONFIG = {
 			'class': 'logging.handlers.SysLogHandler',
 			'level': 'INFO',
 			'formatter': 'sysfmt'
+		},
+		'lacrelog': {
+			'class': 'logging.FileHandler',
+			'level': 'INFO',
+			'formatter': 'sysfmt',
+			'filename': 'lacre.log'
 		}
 	},
 	'root': {
 		'level': 'INFO',
-		'handlers': ['syslog']
+		'handlers': ['syslog', 'lacrelog']
 	}
 }
 

lacre/config.py

@@ -13,6 +13,11 @@ import os
 # testable.
 CONFIG_PATH_ENV = "GPG_MAILGATE_CONFIG"
 
+# List of mandatory configuration parameters.  Each item on this list should be
+# a pair: a section name and a parameter name.
+MANDATORY_CONFIG_ITEMS = [("relay", "host"),
+						  ("relay", "port")]
+
 # Global dict to keep configuration parameters.  It's hidden behind several
 # utility functions to make it easy to replace it with ConfigParser object in
 # the future.
@@ -68,3 +73,15 @@ def config_item_set(section, key) -> bool:
 def config_item_equals(section, key, value) -> bool:
 	global cfg
 	return section in cfg and key in cfg[section] and cfg[section][key] == value
+
+def validate_config():
+	"""Checks whether the configuration is complete.
+
+	Returns a list of missing parameters, so an empty list means
+	configuration is complete.
+	"""
+	missing = []
+	for (section, param) in MANDATORY_CONFIG_ITEMS:
+		if not config_item_set(section, param):
+			missing.append((section, param))
+	return missing

lacre/text.py

@@ -0,0 +1,11 @@
+import sys
+
+def parse_content_type(content_type):
+	split_at = content_type.find(';')
+	if split_at < 0:
+		return (content_type, sys.getdefaultencoding())
+	second_part = content_type[split_at+1 : ].strip()
+	if second_part.startswith('charset'):
+		return (content_type[0 : split_at], second_part[second_part.index('=') + 1 : ].strip())
+	else:
+		return (content_type[0 : split_at], sys.getdefaultencoding())

test/test_lacre_text.py

@@ -0,0 +1,18 @@
+import lacre.text
+import sys
+
+import unittest
+
+class LacreTextTest(unittest.TestCase):
+	def test_parse_content_type(self):
+		(mtype, mcharset) = lacre.text.parse_content_type('text/plain')
+		self.assertEqual(mtype, 'text/plain')
+		self.assertEqual(mcharset, sys.getdefaultencoding())
+
+		(mtype, mcharset) = lacre.text.parse_content_type('text/plain; charset="UTF-8"')
+		self.assertEqual(mtype, 'text/plain')
+		self.assertEqual(mcharset, '"UTF-8"')
+
+		(mtype, mcharset) = lacre.text.parse_content_type('text/plain; some-param="Some Value"')
+		self.assertEqual(mtype, 'text/plain')
+		self.assertEqual(mcharset, sys.getdefaultencoding())