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

2 files changed, 25 insertions, 22 deletions

diff --git a/synapse/app/__init__.py b/synapse/app/__init__.py
index b45adafdd3..f56f5fcc13 100644
--- a/synapse/app/__init__.py
+++ b/synapse/app/__init__.py
@@ -12,15 +12,38 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
+import logging
 import sys
 
 from synapse import python_dependencies  # noqa: E402
 
 sys.dont_write_bytecode = True
 
+logger = logging.getLogger(__name__)
+
 try:
     python_dependencies.check_requirements()
 except python_dependencies.DependencyException as e:
     sys.stderr.writelines(e.message)
     sys.exit(1)
+
+
+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
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