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plugin/cache: key cache on Checking Disabled (CD) bit (#6354)

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* plugin/cache: key cache on Checking Disabled (CD) bit

Key the cache on CD bit, which effectively separates the entries for
queries with CD disabled or enabled.

Signed-off-by: Grant Spence <gspence@redhat.com>
This commit is contained in:
Grant Spence 2023-11-10 07:00:47 -08:00 • committed by GitHub
parent 42d0c75d04
commit 997c7f9539
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GPG key ID: 4AEE18F83AFDEB23
5 changed files with 520 additions and 287 deletions
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16
plugin/cache/cache.go vendored
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@ -79,7 +79,7 @@ func New() *Cache {
// key returns key under which we store the item, -1 will be returned if we don't store the message.
// Currently we do not cache Truncated, errors zone transfers or dynamic update messages.
// qname holds the already lowercased qname.
func key(qname string, m *dns.Msg, t response.Type, do bool) (bool, uint64) {
func key(qname string, m *dns.Msg, t response.Type, do, cd bool) (bool, uint64) {
// We don't store truncated responses.
if m.Truncated {
return false, 0
@ -89,13 +89,13 @@ func key(qname string, m *dns.Msg, t response.Type, do bool) (bool, uint64) {
return false, 0
}
return true, hash(qname, m.Question[0].Qtype, do)
return true, hash(qname, m.Question[0].Qtype, do, cd)
}
var one = []byte("1")
var zero = []byte("0")
func hash(qname string, qtype uint16, do bool) uint64 {
func hash(qname string, qtype uint16, do, cd bool) uint64 {
h := fnv.New64()
if do {
@ -104,6 +104,12 @@ func hash(qname string, qtype uint16, do bool) uint64 {
h.Write(zero)
}
if cd {
h.Write(one)
} else {
h.Write(zero)
}
h.Write([]byte{byte(qtype >> 8)})
h.Write([]byte{byte(qtype)})
h.Write([]byte(qname))
@ -129,6 +135,7 @@ type ResponseWriter struct {
server string // Server handling the request.
do bool // When true the original request had the DO bit set.
cd bool // When true the original request had the CD bit set.
ad bool // When true the original request had the AD bit set.
prefetch bool // When true write nothing back to the client.
remoteAddr net.Addr
@ -159,6 +166,7 @@ func newPrefetchResponseWriter(server string, state request.Request, c *Cache) *
state: state,
server: server,
do: state.Do(),
cd: state.Req.CheckingDisabled,
prefetch: true,
remoteAddr: addr,
}
@ -177,7 +185,7 @@ func (w *ResponseWriter) WriteMsg(res *dns.Msg) error {
mt, _ := response.Typify(res, w.now().UTC())
// key returns empty string for anything we don't want to cache.
hasKey, key := key(w.state.Name(), res, mt, w.do)
hasKey, key := key(w.state.Name(), res, mt, w.do, w.cd)
msgTTL := dnsutil.MinimalTTL(res, mt)
var duration time.Duration