From 39f4b5af72f3aca0174476235f43915477f20adb Mon Sep 17 00:00:00 2001
From: menakite <29005531+menakite@users.noreply.github.com>
Date: Wed, 14 Aug 2024 19:36:54 +0200
Subject: [PATCH] cache: move setting EDE "Stale Answer" to the the serve_stale
 module.

It is not guaranteed yet that the request will finish in state DONE.
This prevents other EDE codes from being applied to the request and in
case the request ends in FAIL state it produces a SERVFAIL answer with
EDE "Stale Answer", which is a bit weird.
Move setting EDEs in answer_finalize in the serve_stale module, where
the proper EDE in case of NXDOMAIN is set too.
---
 lib/cache/api.c                     |  4 +---
 modules/serve_stale/serve_stale.lua | 18 +++++++++++++++++-
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/lib/cache/api.c b/lib/cache/api.c
index 0cd185346..046dae203 100644
--- a/lib/cache/api.c
+++ b/lib/cache/api.c
@@ -237,9 +237,7 @@ int32_t get_new_ttl(const struct entry_h *entry, const struct kr_query *qry,
 		int res_stale = qry->stale_cb(res, owner, type, qry);
 		if (res_stale >= 0) {
 			VERBOSE_MSG(qry, "responding with stale answer\n");
-			/* LATER: Perhaps we could use a more specific Stale
-			 * NXDOMAIN Answer code for applicable responses. */
-			kr_request_set_extended_error(qry->request, KNOT_EDNS_EDE_STALE, "6Q6X");
+			qry->request->stale_accounted = true;
 			return res_stale;
 		}
 	}
diff --git a/modules/serve_stale/serve_stale.lua b/modules/serve_stale/serve_stale.lua
index c1528e804..7aa2ee787 100644
--- a/modules/serve_stale/serve_stale.lua
+++ b/modules/serve_stale/serve_stale.lua
@@ -11,7 +11,6 @@ M.callback = ffi.cast("kr_stale_cb",
 	function (ttl, _, _, qry)
 		--log_debug(ffi.C.SRVSTALE, '   => called back with TTL: ' .. tostring(ttl))
 		if ttl + 3600 * 24 > 0 then -- at most one day stale
-			qry.request.stale_accounted = true
 			return 1
 		else
 			return -1
@@ -39,6 +38,23 @@ M.layer = {
 
 		return state
 	end,
+
+	answer_finalize = function (state, req)
+		local qry = req:resolved()
+		if state ~= kres.DONE or qry == nil then
+			return state
+		end
+
+		if req.stale_accounted and qry.stale_cb ~= nil then
+			if req.answer:rcode() == kres.rcode.NOERROR then
+				req:set_extended_error(kres.extended_error.STALE, 'WFAC')
+			elseif req.answer:rcode() == kres.rcode.NXDOMAIN then
+				req:set_extended_error(kres.extended_error.STALE_NXD, 'QSF6')
+			end
+		end
+
+		return state
+	end,
 }
 
 return M