filtermail: only remove one linebreak

See
<https://docs.python.org/3/library/asyncio-eventloop.html#executing-code-in-thread-or-process-pools>
for the documentation.

This should avoid processing of large messages from hogging asyncio
thread and delaying async operations like accepting new connections.

CHANGELOG.md

@@ -2,6 +2,15 @@
 
 ## untagged
 
+- filtermail: run CPU-intensive handle_DATA in a thread pool executor
+  ([#676](https://github.com/chatmail/relay/pull/676))
+
+- don't use the complicated logging module in filtermail to exclude a potential source of errors. 
+  ([#674](https://github.com/chatmail/relay/pull/674))
+
+- Specify nginx.conf to only handle `mail_domain`, www, and mta-sts domains
+  ([#636](https://github.com/chatmail/relay/pull/636))
+
 - Setup TURN server
   ([#621](https://github.com/chatmail/relay/pull/621))
 

chatmaild/src/chatmaild/filtermail.py

@@ -2,7 +2,6 @@
 import asyncio
 import base64
 import binascii
-import logging
 import sys
 import time
 from email import policy
@@ -105,8 +104,8 @@ def check_armored_payload(payload: str, outgoing: bool):
     # Disallow comments in outgoing messages
     version_comment = "Version: "
     if payload.startswith(version_comment):
-        version_line = payload.splitlines()[0]
-        payload = payload.removeprefix(version_line)
+        splitindex = payload.find("\r\n") + 2
+        payload = payload[splitindex:]
         if outgoing:
             return False
 
@@ -229,7 +228,7 @@ class OutgoingBeforeQueueHandler:
         self.send_rate_limiter = SendRateLimiter()
 
     async def handle_MAIL(self, server, session, envelope, address, mail_options):
-        logging.info(f"handle_MAIL from {address}")
+        log_info(f"handle_MAIL from {address}")
         envelope.mail_from = address
         max_sent = self.config.max_user_send_per_minute
         if not self.send_rate_limiter.is_sending_allowed(address, max_sent):
@@ -242,11 +241,15 @@ class OutgoingBeforeQueueHandler:
         return "250 OK"
 
     async def handle_DATA(self, server, session, envelope):
-        logging.info("handle_DATA before-queue")
+        loop = asyncio.get_running_loop()
+        return await loop.run_in_executor(None, self.sync_handle_DATA, envelope)
+
+    def sync_handle_DATA(self, envelope):
+        log_info("handle_DATA before-queue")
         error = self.check_DATA(envelope)
         if error:
             return error
-        logging.info("re-injecting the mail that passed checks")
+        log_info("re-injecting the mail that passed checks")
         client = SMTPClient("localhost", self.config.postfix_reinject_port)
         client.sendmail(
             envelope.mail_from, envelope.rcpt_tos, envelope.original_content
@@ -255,7 +258,7 @@ class OutgoingBeforeQueueHandler:
 
     def check_DATA(self, envelope):
         """the central filtering function for e-mails."""
-        logging.info(f"Processing DATA message from {envelope.mail_from}")
+        log_info(f"Processing DATA message from {envelope.mail_from}")
 
         message = BytesParser(policy=policy.default).parsebytes(envelope.content)
         mail_encrypted = check_encrypted(message, outgoing=True)
@@ -295,11 +298,15 @@ class IncomingBeforeQueueHandler:
         self.config = config
 
     async def handle_DATA(self, server, session, envelope):
-        logging.info("handle_DATA before-queue")
+        loop = asyncio.get_running_loop()
+        return await loop.run_in_executor(None, self.sync_handle_DATA, envelope)
+
+    def sync_handle_DATA(self, envelope):
+        log_info("handle_DATA before-queue")
         error = self.check_DATA(envelope)
         if error:
             return error
-        logging.info("re-injecting the mail that passed checks")
+        log_info("re-injecting the mail that passed checks")
 
         # the smtp daemon on reinject_port_incoming gives it to dkim milter
         # which looks at source address to determine whether to verify or sign
@@ -315,7 +322,7 @@ class IncomingBeforeQueueHandler:
 
     def check_DATA(self, envelope):
         """the central filtering function for e-mails."""
-        logging.info(f"Processing DATA message from {envelope.mail_from}")
+        log_info(f"Processing DATA message from {envelope.mail_from}")
 
         message = BytesParser(policy=policy.default).parsebytes(envelope.content)
         mail_encrypted = check_encrypted(message, outgoing=False)
@@ -357,16 +364,19 @@ class SendRateLimiter:
         return False
 
 
+def log_info(msg):
+    print(msg, file=sys.stderr)
+
+
 def main():
     args = sys.argv[1:]
     assert len(args) == 2
     config = read_config(args[0])
     mode = args[1]
-    logging.basicConfig(level=logging.WARN)
     loop = asyncio.new_event_loop()
     asyncio.set_event_loop(loop)
     assert mode in ["incoming", "outgoing"]
     task = asyncmain_beforequeue(config, mode)
     loop.create_task(task)
-    logging.info("entering serving loop")
+    log_info("entering serving loop")
     loop.run_forever()

cmdeploy/src/cmdeploy/nginx/nginx.conf.j2

@@ -66,7 +66,7 @@ http {
 
 		index index.html index.htm;
 
-		server_name _;
+		server_name {{ config.domain_name }} www.{{ config.domain_name }} mta-sts.{{ config.domain_name }};
 
 		access_log syslog:server=unix:/dev/log,facility=local7;