Remove various bits of compatibility code for Python <3.6 (#9879)

I went through and removed a bunch of cruft that was lying around for compatibility with old Python versions. This PR also will now prevent Synapse from starting unless you're running Python 3.6+.

3 files changed, 4 insertions, 11 deletions

diff --git a/synapse/rest/admin/users.py b/synapse/rest/admin/users.py

index edda7861fa..8c9d21d3ea 100644
--- a/synapse/rest/admin/users.py
+++ b/synapse/rest/admin/users.py
@@ -14,6 +14,7 @@
 import hashlib
 import hmac
 import logging
+import secrets
 from http import HTTPStatus
 from typing import TYPE_CHECKING, Dict, List, Optional, Tuple
 
@@ -375,7 +376,7 @@ class UserRegisterServlet(RestServlet):
         """
         self._clear_old_nonces()
 
-        nonce = self.hs.get_secrets().token_hex(64)
+        nonce = secrets.token_hex(64)
         self.nonces[nonce] = int(self.reactor.seconds())
         return 200, {"nonce": nonce}
 
diff --git a/synapse/rest/consent/consent_resource.py b/synapse/rest/consent/consent_resource.py

index c4550d3cf0..b19cd8afc5 100644
--- a/synapse/rest/consent/consent_resource.py
+++ b/synapse/rest/consent/consent_resource.py
@@ -32,14 +32,6 @@ TEMPLATE_LANGUAGE = "en"
 
 logger = logging.getLogger(__name__)
 
-# use hmac.compare_digest if we have it (python 2.7.7), else just use equality
-if hasattr(hmac, "compare_digest"):
-    compare_digest = hmac.compare_digest
-else:
-
-    def compare_digest(a, b):
-        return a == b
-
 
 class ConsentResource(DirectServeHtmlResource):
     """A twisted Resource to display a privacy policy and gather consent to it
@@ -209,5 +201,5 @@ class ConsentResource(DirectServeHtmlResource):
             .encode("ascii")
         )
 
-        if not compare_digest(want_mac, userhmac):
+        if not hmac.compare_digest(want_mac, userhmac):
             raise SynapseError(HTTPStatus.FORBIDDEN, "HMAC incorrect")
diff --git a/synapse/rest/media/v1/filepath.py b/synapse/rest/media/v1/filepath.py

index 4088e7a059..09531ebf54 100644
--- a/synapse/rest/media/v1/filepath.py
+++ b/synapse/rest/media/v1/filepath.py
@@ -21,7 +21,7 @@ from typing import Callable, List
 NEW_FORMAT_ID_RE = re.compile(r"^\d\d\d\d-\d\d-\d\d")
 
 
-def _wrap_in_base_path(func: "Callable[..., str]") -> "Callable[..., str]":
+def _wrap_in_base_path(func: Callable[..., str]) -> Callable[..., str]:
     """Takes a function that returns a relative path and turns it into an
     absolute path based on the location of the primary media store
     """