Initial commit

coredns_plugin/refuseany/refuseany.go

@@ -0,0 +1,96 @@
+package refuseany
+
+import (
+	"fmt"
+	"log"
+	"sync"
+
+	"github.com/coredns/coredns/core/dnsserver"
+	"github.com/coredns/coredns/plugin"
+	"github.com/coredns/coredns/plugin/metrics"
+	"github.com/coredns/coredns/request"
+	"github.com/mholt/caddy"
+	"github.com/miekg/dns"
+	"github.com/prometheus/client_golang/prometheus"
+	"golang.org/x/net/context"
+)
+
+type Plugin struct {
+	Next plugin.Handler
+}
+
+func (p *Plugin) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
+	if len(r.Question) != 1 {
+		// google DNS, bind and others do the same
+		return dns.RcodeFormatError, fmt.Errorf("Got DNS request with != 1 questions")
+	}
+
+	q := r.Question[0]
+	if q.Qtype == dns.TypeANY {
+		log.Printf("Got request with type ANY, will respond with NOTIMP\n")
+
+		state := request.Request{W: w, Req: r, Context: ctx}
+		rcode := dns.RcodeNotImplemented
+
+		m := new(dns.Msg)
+		m.SetRcode(r, rcode)
+		state.SizeAndDo(m)
+		err := state.W.WriteMsg(m)
+		if err != nil {
+			log.Printf("Got error %s\n", err)
+			return dns.RcodeServerFailure, err
+		}
+		return rcode, nil
+	} else {
+		return plugin.NextOrFailure(p.Name(), p.Next, ctx, w, r)
+	}
+}
+
+func init() {
+	caddy.RegisterPlugin("refuseany", caddy.Plugin{
+		ServerType: "dns",
+		Action:     setup,
+	})
+}
+
+func setup(c *caddy.Controller) error {
+	p := &Plugin{}
+	config := dnsserver.GetConfig(c)
+
+	config.AddPlugin(func(next plugin.Handler) plugin.Handler {
+		p.Next = next
+		return p
+	})
+
+	c.OnStartup(func() error {
+		once.Do(func() {
+			m := dnsserver.GetConfig(c).Handler("prometheus")
+			if m == nil {
+				return
+			}
+			if x, ok := m.(*metrics.Metrics); ok {
+				x.MustRegister(ratelimited)
+			}
+		})
+		return nil
+	})
+
+	return nil
+}
+
+func newDnsCounter(name string, help string) prometheus.Counter {
+	return prometheus.NewCounter(prometheus.CounterOpts{
+		Namespace: plugin.Namespace,
+		Subsystem: "refuseany",
+		Name:      name,
+		Help:      help,
+	})
+}
+
+var (
+	ratelimited = newDnsCounter("refusedany_total", "Count of ANY requests that have been dropped")
+)
+
+func (d *Plugin) Name() string { return "refuseany" }
+
+var once sync.Once