ACME config cleanups (#4525)

* Handle listening for ACME requests on IPv6 addresses

the weird url-but-not-actually-a-url-string doesn't handle IPv6 addresses
without extra quoting. Building a string which you are about to parse again
seems like a weird choice. Let's just use listenTCP, which is consistent with
what we do elsewhere.

* Clean up the default ACME config

make it look a bit more consistent with everything else, and tweak the defaults
to listen on port 80.

* newsfile

1 files changed, 1 insertions, 21 deletions

diff --git a/synapse/app/_base.py b/synapse/app/_base.py
index 3840c663ab..5b97a54d45 100644
--- a/synapse/app/_base.py
+++ b/synapse/app/_base.py
@@ -22,6 +22,7 @@ from daemonize import Daemonize
 
 from twisted.internet import error, reactor
 
+from synapse.app import check_bind_error
 from synapse.util import PreserveLoggingContext
 from synapse.util.rlimit import change_resource_limit
 
@@ -188,24 +189,3 @@ def listen_ssl(
 
     logger.info("Synapse now listening on port %d (TLS)", port)
     return r
-
-
-def check_bind_error(e, address, bind_addresses):
-    """
-    This method checks an exception occurred while binding on 0.0.0.0.
-    If :: is specified in the bind addresses a warning is shown.
-    The exception is still raised otherwise.
-
-    Binding on both 0.0.0.0 and :: causes an exception on Linux and macOS
-    because :: binds on both IPv4 and IPv6 (as per RFC 3493).
-    When binding on 0.0.0.0 after :: this can safely be ignored.
-
-    Args:
-        e (Exception): Exception that was caught.
-        address (str): Address on which binding was attempted.
-        bind_addresses (list): Addresses on which the service listens.
-    """
-    if address == '0.0.0.0' and '::' in bind_addresses:
-        logger.warn('Failed to listen on 0.0.0.0, continuing because listening on [::]')
-    else:
-        raise e