1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
|
package cache
import (
"github.com/miekg/coredns/middleware"
"github.com/miekg/coredns/request"
"github.com/miekg/dns"
"github.com/prometheus/client_golang/prometheus"
"golang.org/x/net/context"
)
// ServeDNS implements the middleware.Handler interface.
func (c Cache) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := request.Request{W: w, Req: r}
qname := state.Name()
qtype := state.QType()
zone := middleware.Zones(c.Zones).Matches(qname)
if zone == "" {
return c.Next.ServeDNS(ctx, w, r)
}
do := state.Do() // might need more from OPT record?
if i, ok := c.get(qname, qtype, do); ok {
resp := i.toMsg(r)
state.SizeAndDo(resp)
w.WriteMsg(resp)
cacheHitCount.WithLabelValues(zone).Inc()
return dns.RcodeSuccess, nil
}
cacheMissCount.WithLabelValues(zone).Inc()
crr := NewCachingResponseWriter(w, c.cache, c.cap)
return c.Next.ServeDNS(ctx, crr, r)
}
func (c Cache) get(qname string, qtype uint16, do bool) (*item, bool) {
nxdomain := nameErrorKey(qname, do)
if i, ok := c.cache.Get(nxdomain); ok {
return i.(*item), true
}
// TODO(miek): delegation was added double check
successOrNoData := successKey(qname, qtype, do)
if i, ok := c.cache.Get(successOrNoData); ok {
return i.(*item), true
}
return nil, false
}
var (
cacheHitCount = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: middleware.Namespace,
Subsystem: subsystem,
Name: "hit_count_total",
Help: "Counter of DNS requests that were found in the cache.",
}, []string{"zone"})
cacheMissCount = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: middleware.Namespace,
Subsystem: subsystem,
Name: "miss_count_total",
Help: "Counter of DNS requests that were not found in the cache.",
}, []string{"zone"})
)
const subsystem = "cache"
func init() {
prometheus.MustRegister(cacheHitCount)
prometheus.MustRegister(cacheMissCount)
}
|
