Add redis SSL configuration options (#15312)

* Add SSL options to redis config

* fix lint issues

* Add documentation and changelog file

* add missing . at the end of the changelog

* Move client context factory to new file

* Rename ssl to tls and fix typo

* fix lint issues

* Added when redis attributes were added

1 files changed, 34 insertions, 0 deletions

diff --git a/synapse/replication/tcp/context.py b/synapse/replication/tcp/context.py
new file mode 100644
index 0000000000..4688b2200b
--- /dev/null
+++ b/synapse/replication/tcp/context.py
@@ -0,0 +1,34 @@
+# Copyright 2023 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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.
+from OpenSSL.SSL import Context
+from twisted.internet import ssl
+
+from synapse.config.redis import RedisConfig
+
+
+class ClientContextFactory(ssl.ClientContextFactory):
+    def __init__(self, redis_config: RedisConfig):
+        self.redis_config = redis_config
+
+    def getContext(self) -> Context:
+        ctx = super().getContext()
+        if self.redis_config.redis_certificate:
+            ctx.use_certificate_file(self.redis_config.redis_certificate)
+        if self.redis_config.redis_private_key:
+            ctx.use_privatekey_file(self.redis_config.redis_private_key)
+        if self.redis_config.redis_ca_file:
+            ctx.load_verify_locations(cafile=self.redis_config.redis_ca_file)
+        elif self.redis_config.redis_ca_path:
+            ctx.load_verify_locations(capath=self.redis_config.redis_ca_path)
+        return ctx