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plugin/cache: configure stale TTL and failure recheck (#8411)

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* plugin/cache: configure stale response TTL

Signed-off-by: houyuwushang <liuluoqianqiu@outlook.com>

* plugin/cache: delay stale refresh retries

Signed-off-by: houyuwushang <liuluoqianqiu@outlook.com>

* plugin/cache: validate stale refresh responses

Signed-off-by: houyuwushang <liuluoqianqiu@outlook.com>

---------

Signed-off-by: houyuwushang <liuluoqianqiu@outlook.com>
This commit is contained in:
houyuwushang
2026-08-14 14:27:42 +08:00
committed by GitHub
parent 6199dc50a5
commit 9520d725d6
8 changed files with 757 additions and 72 deletions
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21
plugin/cache/cache.go vendored
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@@ -46,6 +46,8 @@ type Cache struct {
staleUpTo time.Duration
verifyStale bool
verifyStaleTimeout time.Duration // 0 means wait for upstream until its own timeout (current default).
staleTTL time.Duration // TTL returned with stale responses; 0 preserves the legacy behavior.
staleRecheck time.Duration // Delay after a failed refresh before another attempt; 0 preserves the legacy behavior.
// Positive/negative zone exceptions
pexcept []string
@@ -468,8 +470,8 @@ type verifyStaleResponseWriter struct {
}
// newVerifyStaleResponseWriter returns a ResponseWriter to be used when verifying stale cache
// entries. It only forward writes if an entry was successfully refreshed according to RFC8767,
// section 4 (response is NoError or NXDomain), and ignores any other response.
// entries. It only forwards matching, complete responses that successfully refresh the data
// according to RFC8767, section 4 (response is NoError or NXDomain), and ignores other responses.
func newVerifyStaleResponseWriter(w *ResponseWriter) *verifyStaleResponseWriter {
return &verifyStaleResponseWriter{
w,
@@ -480,11 +482,18 @@ func newVerifyStaleResponseWriter(w *ResponseWriter) *verifyStaleResponseWriter
// WriteMsg implements the dns.ResponseWriter interface.
func (w *verifyStaleResponseWriter) WriteMsg(res *dns.Msg) error {
w.refreshed = false
if res.Rcode == dns.RcodeSuccess || res.Rcode == dns.RcodeNameError {
w.refreshed = true
return w.ResponseWriter.WriteMsg(res) // stores to the cache and send to client
if res == nil || res.Truncated || !w.state.Match(res) {
return nil
}
return nil // else discard
responseType, _ := response.Typify(res, w.now().UTC())
if responseType == response.OtherError || responseType == response.Meta || responseType == response.Update {
return nil
}
if res.Rcode != dns.RcodeSuccess && res.Rcode != dns.RcodeNameError {
return nil
}
w.refreshed = true
return w.ResponseWriter.WriteMsg(res) // stores to the cache and sends to the client
}
const (