From 1c41b05c8c98f0b9157c791b5b8ebf5f9fe85acf Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Wed, 21 Mar 2018 17:46:26 +0000
Subject: [PATCH] Add Cache-Control headers to all JSON APIs
It is especially important that sync requests don't get cached, as if a
sync returns the same token given then the client will call sync with
the same parameters again. If the previous response was cached it will
get reused, resulting in the client tight looping making the same
request and never making any progress.
In general, clients will expect to get up to date data when requesting
APIs, and so its safer to do a blanket no cache policy than only
whitelisting APIs that we know will break things if they get cached.
---
synapse/http/server.py | 1 +
1 file changed, 1 insertion(+)
diff --git a/synapse/http/server.py b/synapse/http/server.py
index 1551db239d..f19c068ef6 100644
--- a/synapse/http/server.py
+++ b/synapse/http/server.py
@@ -488,6 +488,7 @@ def respond_with_json_bytes(request, code, json_bytes, send_cors=False,
request.setHeader(b"Content-Type", b"application/json")
request.setHeader(b"Server", version_string)
request.setHeader(b"Content-Length", b"%d" % (len(json_bytes),))
+ request.setHeader(b"Cache-Control", b"no-cache, no-store, must-revalidate")
if send_cors:
set_cors_headers(request)
--
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