postfix: wrap IPv6 CIDRs in square brackets for RELAYNETS

The RELAYNETS environment variable is used for configuring both postfix
`mynetworks` and rspamd `local_networks`. Postfix requires IPv6
addresses to be wrapped in square brackets (eg. [2001:db8::]/64).

core/postfix/start.py

@@ -6,6 +6,7 @@ import shutil
 import multiprocessing
 import logging as log
 import sys
+import re
 
 from podop import run_server
 from pwd import getpwnam
@@ -50,6 +51,10 @@ os.environ["LMTP_ADDRESS"] = system.get_host_address_from_environment("LMTP", "i
 os.environ["POSTFIX_LOG_SYSLOG"] = os.environ.get("POSTFIX_LOG_SYSLOG","local")
 os.environ["POSTFIX_LOG_FILE"] = os.environ.get("POSTFIX_LOG_FILE", "")
 
+# Postfix requires IPv6 addresses to be wrapped in square brackets
+if 'RELAYNETS' in os.environ:
+    os.environ["RELAYNETS"] = re.sub(r'([0-9a-fA-F]+:[0-9a-fA-F:]+)/', '[\\1]/', os.environ["RELAYNETS"])
+
 for postfix_file in glob.glob("/conf/*.cf"):
     conf.jinja(postfix_file, os.environ, os.path.join("/etc/postfix", os.path.basename(postfix_file)))
 

towncrier/newsfragments/2325.bugfix

@@ -0,0 +1 @@
+postfix: wrap IPv6 CIDRs in square brackets for RELAYNETS