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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 15:26:00 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 15:26:00 +0000
commit830407e88f9d40d954356c3754f2647f91d5c06a (patch)
treed6a0ece6feea91f3c656166dbaa884ef8a29740e /modules/serve_stale/serve_stale.lua
parentInitial commit. (diff)
downloadknot-resolver-830407e88f9d40d954356c3754f2647f91d5c06a.tar.xz
knot-resolver-830407e88f9d40d954356c3754f2647f91d5c06a.zip
Adding upstream version 5.6.0.upstream/5.6.0upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r--modules/serve_stale/serve_stale.lua42
1 files changed, 42 insertions, 0 deletions
diff --git a/modules/serve_stale/serve_stale.lua b/modules/serve_stale/serve_stale.lua
new file mode 100644
index 0000000..faf07fb
--- /dev/null
+++ b/modules/serve_stale/serve_stale.lua
@@ -0,0 +1,42 @@
+-- SPDX-License-Identifier: GPL-3.0-or-later
+local M = {} -- the module
+
+local ffi = require('ffi')
+
+-- Beware that the timeout is only considered at certain points in time;
+-- approximately at multiples of KR_CONN_RTT_MAX.
+M.timeout = 3*sec
+
+M.callback = ffi.cast("kr_stale_cb",
+ function (ttl) --, name, type, qry)
+ --log_debug(ffi.C.SRVSTALE, ' => called back with TTL: ' .. tostring(ttl))
+ if ttl + 3600 * 24 > 0 then -- at most one day stale
+ return 1
+ else
+ return -1
+ end
+ end)
+
+M.layer = {
+ produce = function (state, req)
+ local qry = req:current()
+ -- Don't do anything for priming, prefetching, etc.
+ -- TODO: not all cases detected ATM.
+ if qry.flags.NO_CACHE then return state end
+
+ local now = ffi.C.kr_now()
+ local deadline = qry.creation_time_mono + M.timeout
+ if now > deadline or qry.flags.NO_NS_FOUND then
+ log_debug(ffi.C.LOG_GRP_SRVSTALE, ' => no reachable NS, using stale data')
+ qry.stale_cb = M.callback
+ -- TODO: probably start the same request that doesn't stale-serve,
+ -- but first we need some detection of non-interactive / internal requests.
+ -- resolve(kres.dname2str(qry.sname), qry.stype, qry.sclass)
+ end
+
+ return state
+ end,
+}
+
+return M
+