Merge pull request 'Handle text data carefully' (#82) from 75-unify-types into master

Reviewed-on: #82

GnuPG/__init__.py

@@ -35,20 +35,6 @@ def build_command(key_home, *args, **kwargs):
 	cmd = ["gpg", '--homedir', key_home] + list(args)
 	return cmd
 
-def private_keys( keyhome ):
-	cmd = build_command(keyhome, '--list-secret-keys', '--with-colons')
-	p = subprocess.Popen( cmd, stdin=None, stdout=subprocess.PIPE, stderr=subprocess.PIPE )
-	p.wait()
-	keys = dict()
-	for line in p.stdout.readlines():
-		if line[0:3] == 'uid' or line[0:3] == 'sec':
-			if ('<' not in line or '>' not in line):
-				continue
-			email = line.split('<')[1].split('>')[0]
-			fingerprint = line.split(':')[4]
-			keys[fingerprint] = email
-	return keys
-
 def public_keys( keyhome ):
 	cmd = build_command(keyhome, '--list-keys', '--with-colons')
 	p = subprocess.Popen( cmd, stdin=None, stdout=subprocess.PIPE, stderr=subprocess.PIPE )
@@ -58,7 +44,7 @@ def public_keys( keyhome ):
 	fingerprint = None
 	email = None
 	for line in p.stdout.readlines():
-		line = line.decode('utf-8')
+		line = line.decode(sys.getdefaultencoding())
 		if line[0:3] == LINE_FINGERPRINT:
 			fingerprint = line.split(':')[POS_FINGERPRINT]
 		if line[0:3] == LINE_USER_ID:

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
 
@@ -113,7 +117,7 @@ def gpg_encrypt( raw_message, recipients ):
 			else:
 				# Log message only if an unknown style is defined
 				if conf.config_item_set('pgp_style', rcpt[0]):
-					LOG.info("Style %s for recipient %s is not known. Use default as fallback." % (conf.get_item("pgp_style", rcpt[0]), rcpt[0]))
+					LOG.debug("Style %s for recipient %s is not known. Use default as fallback." % (conf.get_item("pgp_style", rcpt[0]), rcpt[0]))
 
 				# If no style is in settings defined for recipient, use default from settings
 				if conf.config_item_equals('default', 'mime_conversion', 'yes'):
@@ -175,19 +179,18 @@ def encrypt_all_payloads_inline( message, gpg_to_cmdline ):
 	return encrypted_payloads
 
 def encrypt_all_payloads_mime( message, gpg_to_cmdline ):
-
 	# Convert a plain text email into PGP/MIME attachment style.  Modeled after enigmail.
-	submsg1 = email.message.Message()
-	submsg1.set_payload("Version: 1\n")
-	submsg1.set_type("application/pgp-encrypted")
-	submsg1.set_param('PGP/MIME version identification', "", 'Content-Description' )
+	pgp_ver_part = email.message.Message()
+	pgp_ver_part.set_payload("Version: 1\n")
+	pgp_ver_part.set_type("application/pgp-encrypted")
+	pgp_ver_part.set_param('PGP/MIME version identification', "", 'Content-Description' )
 
-	submsg2 = email.message.Message()
-	submsg2.set_type("application/octet-stream")
-	submsg2.set_param('name', "encrypted.asc")
-	submsg2.set_param('OpenPGP encrypted message', "", 'Content-Description' )
-	submsg2.set_param('inline', "",                'Content-Disposition' )
-	submsg2.set_param('filename', "encrypted.asc", 'Content-Disposition' )
+	encrypted_part = email.message.Message()
+	encrypted_part.set_type("application/octet-stream")
+	encrypted_part.set_param('name', "encrypted.asc")
+	encrypted_part.set_param('OpenPGP encrypted message', "", 'Content-Description' )
+	encrypted_part.set_param('inline', "",                'Content-Disposition' )
+	encrypted_part.set_param('filename', "encrypted.asc", 'Content-Disposition' )
 
 	if isinstance(message.get_payload(), str):
 		# WTF!  It seems to swallow the first line.  Not sure why.  Perhaps
@@ -195,13 +198,16 @@ def encrypt_all_payloads_mime( message, gpg_to_cmdline ):
 		# Workaround it here by prepending a blank line.
 		# This happens only on text only messages.
 		additionalSubHeader=""
+		encoding = sys.getdefaultencoding()
 		if 'Content-Type' in message and not message['Content-Type'].startswith('multipart'):
 			additionalSubHeader="Content-Type: "+message['Content-Type']+"\n"
-		submsg2.set_payload(additionalSubHeader+"\n" +message.get_payload(decode=True))
+			(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
 	else:
 		processed_payloads = generate_message_from_payloads(message)
-		submsg2.set_payload(processed_payloads.as_string())
+		encrypted_part.set_payload(processed_payloads.as_string())
 		check_nested = False
 
 	message.preamble = "This is an OpenPGP/MIME encrypted message (RFC 2440 and 3156)"
@@ -217,13 +223,13 @@ def encrypt_all_payloads_mime( message, gpg_to_cmdline ):
 	else:
 		message['Content-Type'] = "multipart/encrypted; protocol=\"application/pgp-encrypted\";\nboundary=\"%s\"\n" % boundary
 
-	return [ submsg1, encrypt_payload(submsg2, gpg_to_cmdline, check_nested) ]
+	return [ pgp_ver_part, encrypt_payload(encrypted_part, gpg_to_cmdline, check_nested) ]
 
 def encrypt_payload( payload, gpg_to_cmdline, check_nested = True ):
 	global LOG
 
 	raw_payload = payload.get_payload(decode=True)
-	if check_nested and b"-----BEGIN PGP MESSAGE-----" in raw_payload and b"-----END PGP MESSAGE-----" in raw_payload:
+	if check_nested and text.is_pgp_inline(raw_payload):
 		LOG.debug("Message is already pgp encrypted. No nested encryption needed.")
 		return payload
 
@@ -297,11 +303,11 @@ def smime_encrypt( raw_message, recipients ):
 
 		s.write(out, p7)
 
-		LOG.debug("Sending message from " + from_addr + " to " + str(smime_to))
+		LOG.debug(f"Sending message from {from_addr} to {smime_to}")
 
 		send_msg(out.read(), smime_to)
 	if unsmime_to:
-		LOG.debug("Unable to find valid S/MIME certificates for " + str(unsmime_to))
+		LOG.debug(f"Unable to find valid S/MIME certificates for {unsmime_to}")
 
 	return unsmime_to
 
@@ -330,22 +336,16 @@ def get_cert_for_email( to_addr, cert_path ):
 	return None
 
 def sanitize_case_sense( address ):
-
 	if conf.config_item_equals('default', 'mail_case_insensitive', 'yes'):
 		address = address.lower()
 	else:
-		if isinstance(address, str):
-			sep = '@'
-		else:
-			sep = b'@'
-		splitted_address = address.split(sep)
+		splitted_address = address.split('@')
 		if len(splitted_address) > 1:
-			address = splitted_address[0] + sep + splitted_address[1].lower()
+			address = splitted_address[0] + '@' + splitted_address[1].lower()
 
 	return address
 
 def generate_message_from_payloads( payloads, message = None ):
-
 	if message == None:
 		message = email.mime.multipart.MIMEMultipart(payloads.get_content_subtype())
 
@@ -358,7 +358,6 @@ def generate_message_from_payloads( payloads, message = None ):
 	return message
 
 def get_first_payload( payloads ):
-
 	if payloads.is_multipart():
 		return get_first_payload(payloads.get_payload(0))
 	else:
@@ -369,10 +368,7 @@ 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 ))
+		LOG.info(f"Sending email to: {recipients!r}")
 		relay = (conf.get_item('relay', 'host'), int(conf.get_item('relay', 'port')))
 		smtp = smtplib.SMTP(relay[0], relay[1])
 		if conf.config_item_equals('relay', 'starttls', 'yes'):
@@ -384,9 +380,7 @@ def send_msg( message, recipients ):
 def sort_recipients( raw_message, from_addr, to_addrs ):
 	global LOG
 
-	recipients_left = list()
-	for recipient in to_addrs:
-		recipients_left.append(sanitize_case_sense(recipient))
+	recipients_left = [sanitize_case_sense(recipient) for recipient in to_addrs]
 
 	# There is no need for nested encryption
 	first_payload = get_first_payload(raw_message)
@@ -396,7 +390,7 @@ def sort_recipients( raw_message, from_addr, to_addrs ):
 		return
 
 	first_payload = first_payload.get_payload(decode=True)
-	if b"-----BEGIN PGP MESSAGE-----" in first_payload and b"-----END PGP MESSAGE-----" in first_payload:
+	if text.is_pgp_inline(first_payload):
 		LOG.debug("Message is already encrypted as PGP/INLINE. Encryption aborted.")
 		send_msg(raw_message.as_string(), recipients_left)
 		return
@@ -423,9 +417,13 @@ 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 +1,24 @@
+import sys
+
+PGP_INLINE_BEGIN = b"-----BEGIN PGP MESSAGE-----"
+PGP_INLINE_END = b"-----END PGP MESSAGE-----"
+
+def parse_content_type(content_type):
+	parts = [p.strip() for p in content_type.split(';')]
+	if len(parts) == 1:
+		# No additional attributes provided.  Use default encoding.
+		return (content_type, sys.getdefaultencoding())
+
+	# At least one attribute provided.  Find out if any of them is named
+	# 'charset' and if so, use it.
+	ctype = parts[0]
+	encoding = [p for p in parts[1:] if p.startswith('charset=') ]
+	if encoding:
+		eq_idx = encoding[0].index('=')
+		return (ctype, encoding[0][eq_idx+1:])
+	else:
+		return (ctype, sys.getdefaultencoding())
+
+def is_pgp_inline(payload):
+	"""Finds out if the payload (bytes) contains PGP/INLINE markers."""
+	return PGP_INLINE_BEGIN in payload and PGP_INLINE_END in payload

test/e2e.ini

@@ -30,7 +30,7 @@ certs: test/certs
 
 [tests]
 # Number of "test-*" sections in this file, describing test cases.
-cases: 6
+cases: 7
 e2e_log: test/logs/e2e.log
 e2e_log_format: %(asctime)s %(pathname)s:%(lineno)d %(levelname)s [%(funcName)s] %(message)s
 e2e_log_datefmt: %Y-%m-%d %H:%M:%S
@@ -72,3 +72,9 @@ descr: Multipart encrypted message to a user with an Ed25519 key.
 to: bob@disposlab
 in: test/msgin/multipart2rsa.msg
 out: -----BEGIN PGP MESSAGE-----
+
+[case-7]
+descr: Clear text message to a user with an RSA key and PGP/MIME enabled in configuration
+to: evan@disposlab
+in: test/msgin/clear2rsa2.msg
+out: -----BEGIN PGP MESSAGE-----

test/e2e_test.py

@@ -51,6 +51,12 @@ def build_config(config):
     cp.add_section("enc_keymap")
     cp.set("enc_keymap", "alice@disposlab", "1CD245308F0963D038E88357973CF4D9387C44D7")
     cp.set("enc_keymap", "bob@disposlab", "19CF4B47ECC9C47AFA84D4BD96F39FDA0E31BB67")
+    cp.set("enc_keymap", "evan@disposlab", "530B1BB2D0CC7971648198BBA4774E507D3AF5BC")
+
+    cp.add_section("pgp_style")
+    # Default style is PGP/Inline, so to cover more branches, one test identity
+    # uses PGP/MIME.
+    cp.set("pgp_style", "evan@disposlab", "mime")
 
     logging.debug(f"Created config with keyhome={config['gpg_keyhome']}, cert_path={config['smime_certpath']} and relay at port {config['port']}")
     return cp

test/msgin/clear2rsa2.msg

@@ -0,0 +1,6 @@
+From: Dave <dave@disposlab
+To: Evan <evan@disposlab>
+Subject: Test
+Content-Type: text/plain; charset="utf-8"
+
+Body of the message.

test/sample.ini

@@ -0,0 +1,3 @@
+[foo]
+bar: quux
+baz: 14

test/test_contracts.py

@@ -0,0 +1,92 @@
+#
+#	gpg-mailgate
+#
+#	This file is part of the gpg-mailgate source code.
+#
+#	gpg-mailgate is free software: you can redistribute it and/or modify
+#	it under the terms of the GNU General Public License as published by
+#	the Free Software Foundation, either version 3 of the License, or
+#	(at your option) any later version.
+#
+#	gpg-mailgate source code is distributed in the hope that it will be useful,
+#	but WITHOUT ANY WARRANTY; without even the implied warranty of
+#	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+#	GNU General Public License for more details.
+#
+#	You should have received a copy of the GNU General Public License
+#	along with gpg-mailgate source code. If not, see <http://www.gnu.org/licenses/>.
+#
+
+"""Unit-tests as contracts for external dependencies.
+
+Unit tests defined here are our contracts for the dependencies used by Lacre.
+Since not all software is documented thoroughly, they are also a form of
+documentation.
+"""
+
+import email
+import unittest
+from configparser import RawConfigParser
+
+class EmailParsingTest(unittest.TestCase):
+	"""This test serves as a package contract and documentation of its behaviour."""
+
+	def test_message_from_bytes_produces_message_with_str_headers(self):
+		rawmsg = b"From: alice@lacre.io\r\n" \
+		  + b"To: bob@lacre.io\r\n" \
+		  + b"Subject: Test message\r\n" \
+		  + b"\r\n" \
+		  + b"Test message from Alice to Bob.\r\n"
+
+		parsed = email.message_from_bytes(rawmsg)
+
+		self.assertEqual(parsed["From"], "alice@lacre.io")
+		self.assertEqual(parsed["To"], "bob@lacre.io")
+		self.assertEqual(parsed["Subject"], "Test message")
+
+	def test_bytes_message_payload_decoded_produces_bytes(self):
+		rawmsg = b"From: alice@lacre.io\r\n" \
+		  + b"To: bob@lacre.io\r\n" \
+		  + b"Subject: Test message\r\n" \
+		  + b"\r\n" \
+		  + b"Test message from Alice to Bob.\r\n"
+
+		parsed = email.message_from_bytes(rawmsg)
+
+		self.assertEqual(parsed.get_payload(), "Test message from Alice to Bob.\r\n")
+		self.assertEqual(parsed.get_payload(decode=True), b"Test message from Alice to Bob.\r\n")
+
+	def test_message_from_string_produces_message_with_str_headers(self):
+		rawmsg = "From: alice@lacre.io\r\n" \
+		  + "To: bob@lacre.io\r\n" \
+		  + "Subject: Test message\r\n" \
+		  + "\r\n" \
+		  + "Test message from Alice to Bob.\r\n"
+
+		parsed = email.message_from_string(rawmsg)
+
+		self.assertEqual(parsed["From"], "alice@lacre.io")
+		self.assertEqual(parsed["To"], "bob@lacre.io")
+		self.assertEqual(parsed["Subject"], "Test message")
+
+	def test_str_message_payload_decoded_produces_bytes(self):
+		rawmsg = "From: alice@lacre.io\r\n" \
+		  + "To: bob@lacre.io\r\n" \
+		  + "Subject: Test message\r\n" \
+		  + "\r\n" \
+		  + "Test message from Alice to Bob.\r\n"
+
+		parsed = email.message_from_string(rawmsg)
+
+		self.assertEqual(parsed.get_payload(), "Test message from Alice to Bob.\r\n")
+		self.assertEqual(parsed.get_payload(decode=True), b"Test message from Alice to Bob.\r\n")
+
+class RawConfigParserTest(unittest.TestCase):
+	def test_config_parser_returns_str(self):
+		cp = RawConfigParser()
+		cp.read("test/sample.ini")
+		self.assertEqual(cp.get("foo", "bar"), "quux")
+		self.assertEqual(cp.get("foo", "baz"), "14")
+
+if __name__ == '__main__':
+	unittest.main()

test/test_lacre_text.py

@@ -0,0 +1,25 @@
+import lacre.text
+import sys
+
+import unittest
+
+class LacreTextTest(unittest.TestCase):
+	def test_parse_content_type_without_charset(self):
+		(mtype, mcharset) = lacre.text.parse_content_type('text/plain')
+		self.assertEqual(mtype, 'text/plain')
+		self.assertEqual(mcharset, sys.getdefaultencoding())
+
+	def test_parse_content_type_with_charset(self):
+		(mtype, mcharset) = lacre.text.parse_content_type('text/plain; charset="UTF-8"')
+		self.assertEqual(mtype, 'text/plain')
+		self.assertEqual(mcharset, '"UTF-8"')
+
+	def test_parse_content_type_with_other_attributes(self):
+		(mtype, mcharset) = lacre.text.parse_content_type('text/plain; some-param="Some Value"')
+		self.assertEqual(mtype, 'text/plain')
+		self.assertEqual(mcharset, sys.getdefaultencoding())
+
+	def test_parse_content_type_with_several_attributes(self):
+		(mtype, mcharset) = lacre.text.parse_content_type('text/plain; charset="UTF-8"; some-param="Some Value"')
+		self.assertEqual(mtype, 'text/plain')
+		self.assertEqual(mcharset, '"UTF-8"')