[Web][Postfix] Add mail policies: per-recipient send/receive rules for mailboxes and groups

data/Dockerfiles/postfix/Dockerfile

@@ -26,6 +26,7 @@ RUN groupadd -g 102 postfix \
 	postfix \
 	postfix-mysql \
 	postfix-pcre \
+	python3 \
 	redis-tools \
 	sasl2-bin \
 	sudo \
@@ -46,6 +47,7 @@ COPY postfix.sh /opt/postfix.sh
 COPY rspamd-pipe-ham /usr/local/bin/rspamd-pipe-ham
 COPY rspamd-pipe-spam /usr/local/bin/rspamd-pipe-spam
 COPY whitelist_forwardinghosts.sh /usr/local/bin/whitelist_forwardinghosts.sh
+COPY mailcow-policy.py /usr/local/bin/mailcow-policy.py
 COPY stop-supervisor.sh /usr/local/sbin/stop-supervisor.sh
 COPY docker-entrypoint.sh /docker-entrypoint.sh
 
@@ -53,6 +55,7 @@ RUN chmod +x /opt/postfix.sh \
   /usr/local/bin/rspamd-pipe-ham \
   /usr/local/bin/rspamd-pipe-spam \
   /usr/local/bin/whitelist_forwardinghosts.sh \
+  /usr/local/bin/mailcow-policy.py \
   /usr/local/sbin/stop-supervisor.sh
 RUN rm -rf /tmp/* /var/tmp/*
 

data/Dockerfiles/postfix/mailcow-policy.py

@@ -0,0 +1,53 @@
+#!/usr/bin/python3
+# Policy service of the mail policies (mailcow-policy in master.cf, spawned by Postfix): reads the policy requests
+# of smtpd and asks the mailcow UI for the action (nginx:8081/mailpolicy.php). Without an answer the recipient is
+# deferred; smtpd only asks while policies or internal aliases exist (mysql_mail_policy_maps.cf).
+
+import http.client
+import re
+import socket
+import sys
+from urllib.parse import urlencode
+
+# one line: DUNNO or a rejection with code and text
+valid_action = re.compile(rb'DUNNO|[45]\d\d [45]\.\d{1,3}\.\d{1,3} [\x20-\x7e]{1,200}')
+unavailable = b'DEFER_IF_PERMIT Mail policy check temporarily unavailable'
+# address of nginx, resolved once per process (a lookup costs more than the check)
+nginx = None
+
+def check(request):
+  global nginx
+  body = urlencode(sorted(request.items())).encode()
+  try:
+    if nginx is None:
+      nginx = socket.gethostbyname('nginx')
+    # http.client sets TCP_NODELAY, so the body is not held back until the headers are acknowledged
+    conn = http.client.HTTPConnection(nginx, 8081, timeout=10)
+    try:
+      conn.request('POST', '/mailpolicy.php', body, {'Host': 'nginx', 'Content-Type': 'application/x-www-form-urlencoded'})
+      response = conn.getresponse()
+      action = response.read()
+    finally:
+      conn.close()
+  except (OSError, http.client.HTTPException):
+    # nginx may have a new address after a restart
+    nginx = None
+    return unavailable
+  return action if response.status == 200 and valid_action.fullmatch(action) else unavailable
+
+def main():
+  request = {}
+  # attributes as bytes: addresses may contain any 8-bit characters
+  for line in sys.stdin.buffer:
+    line = line.rstrip(b'\r\n')
+    if line:
+      name, separator, value = line.partition(b'=')
+      if separator:
+        request[name] = value
+      continue
+    sys.stdout.buffer.write(b'action=' + check(request) + b'\n\n')
+    sys.stdout.buffer.flush()
+    request = {}
+
+if __name__ == '__main__':
+  main()

data/Dockerfiles/postfix/postfix.sh

@@ -15,6 +15,21 @@ until dig +short mailcow.email > /dev/null; do
   sleep 1
 done
 
+# Wait for updated schema (DB_VERSION from docker-compose.yml), the maps read tables the init_db of php-fpm creates on updates
+DBV_NOW=$(mariadb --ssl=false --socket=/var/run/mysqld/mysqld.sock -u ${DBUSER} -p${DBPASS} ${DBNAME} -e "SELECT version FROM versions WHERE application = 'db_schema';" -BN 2>/dev/null)
+DBV_WAIT=0
+while [[ "${DBV_NOW}" != "${DB_VERSION}" ]] && [[ ${DBV_WAIT} -lt 60 ]]; do
+  echo "Waiting for schema update..."
+  sleep 5
+  DBV_WAIT=$((DBV_WAIT + 1))
+  DBV_NOW=$(mariadb --ssl=false --socket=/var/run/mysqld/mysqld.sock -u ${DBUSER} -p${DBPASS} ${DBNAME} -e "SELECT version FROM versions WHERE application = 'db_schema';" -BN 2>/dev/null)
+done
+if [[ "${DBV_NOW}" != "${DB_VERSION}" ]]; then
+  echo -e "\e[31mDB schema is ${DBV_NOW}, expected ${DB_VERSION} - starting anyway, check the php-fpm log (init_db)\e[0m"
+else
+  echo "DB schema is ${DBV_NOW}"
+fi
+
 cat <<EOF > /etc/aliases
 # Autogenerated by mailcow
 null: /dev/null
@@ -224,6 +239,20 @@ query = SELECT CONCAT_WS(':', username, password) AS auth_data FROM transports
   LIMIT 1;
 EOF
 
+# Mail policies: while policies or internal aliases exist, smtpd asks the policy service (mailcow_mail_policy in main.cf)
+cat <<EOF > /opt/postfix/conf/sql/mysql_mail_policy_maps.cf
+# Autogenerated by mailcow
+user = ${DBUSER}
+password = ${DBPASS}
+hosts = unix:/var/run/mysqld/mysqld.sock
+dbname = ${DBNAME}
+query = SELECT 'mailcow_mail_policy' FROM mail_policy_member
+  JOIN mail_policy ON mail_policy.id = mail_policy_member.policy_id
+  WHERE mail_policy.active = '1' AND '%s' != ''
+  UNION SELECT 'mailcow_mail_policy' FROM alias WHERE internal = '1' AND active = '1'
+  LIMIT 1;
+EOF
+
 cat <<EOF > /opt/postfix/conf/sql/mysql_virtual_alias_domain_maps.cf
 # Autogenerated by mailcow
 user = ${DBUSER}