c4ab98c6e3
This checks if the next middleware to be called is nil, and if so returns ServerFailure and an error. This makes the next calling more robust and saves some lines of code. Also prefix the error with the name of the middleware to aid in debugging.
96 lines
2.4 KiB
Go
96 lines
2.4 KiB
Go
package cache
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import (
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"time"
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"github.com/miekg/coredns/middleware"
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"github.com/miekg/coredns/request"
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"github.com/miekg/dns"
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"github.com/prometheus/client_golang/prometheus"
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"golang.org/x/net/context"
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)
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// ServeDNS implements the middleware.Handler interface.
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func (c *Cache) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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state := request.Request{W: w, Req: r}
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qname := state.Name()
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qtype := state.QType()
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zone := middleware.Zones(c.Zones).Matches(qname)
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if zone == "" {
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return c.Next.ServeDNS(ctx, w, r)
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}
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do := state.Do() // TODO(): might need more from OPT record? Like the actual bufsize?
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if i, ok, expired := c.get(qname, qtype, do); ok && !expired {
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resp := i.toMsg(r)
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state.SizeAndDo(resp)
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w.WriteMsg(resp)
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return dns.RcodeSuccess, nil
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}
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crr := &ResponseWriter{w, c}
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return middleware.NextOrFailure(c.Name(), c.Next, ctx, crr, r)
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}
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// Name implements the Handler interface.
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func (c *Cache) Name() string { return "cache" }
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func (c *Cache) get(qname string, qtype uint16, do bool) (*item, bool, bool) {
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k := rawKey(qname, qtype, do)
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if i, ok := c.ncache.Get(k); ok {
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cacheHits.WithLabelValues(Denial).Inc()
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return i.(*item), ok, i.(*item).expired(time.Now())
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}
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if i, ok := c.pcache.Get(k); ok {
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cacheHits.WithLabelValues(Success).Inc()
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return i.(*item), ok, i.(*item).expired(time.Now())
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}
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cacheMisses.Inc()
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return nil, false, false
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}
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var (
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cacheSize = prometheus.NewGaugeVec(prometheus.GaugeOpts{
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Namespace: middleware.Namespace,
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Subsystem: subsystem,
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Name: "size",
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Help: "The number of elements in the cache.",
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}, []string{"type"})
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cacheCapacity = prometheus.NewGaugeVec(prometheus.GaugeOpts{
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Namespace: middleware.Namespace,
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Subsystem: subsystem,
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Name: "capacity",
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Help: "The cache's capacity.",
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}, []string{"type"})
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cacheHits = prometheus.NewCounterVec(prometheus.CounterOpts{
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Namespace: middleware.Namespace,
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Subsystem: subsystem,
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Name: "hits_total",
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Help: "The count of cache hits.",
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}, []string{"type"})
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cacheMisses = prometheus.NewCounter(prometheus.CounterOpts{
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Namespace: middleware.Namespace,
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Subsystem: subsystem,
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Name: "misses_total",
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Help: "The count of cache misses.",
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})
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)
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const subsystem = "cache"
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func init() {
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prometheus.MustRegister(cacheSize)
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prometheus.MustRegister(cacheCapacity)
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prometheus.MustRegister(cacheHits)
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prometheus.MustRegister(cacheMisses)
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}
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