AdGuardHome/coredns_plugin/refuseany/refuseany.go

94 lines
2.1 KiB
Go

package refuseany
import (
"fmt"
"log"
"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 plug struct {
Next plugin.Handler
}
// ServeDNS handles the DNS request and refuses if it's an ANY request
func (p *plug) 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
}
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 := &plug{}
config := dnsserver.GetConfig(c)
config.AddPlugin(func(next plugin.Handler) plugin.Handler {
p.Next = next
return p
})
c.OnStartup(func() error {
m := dnsserver.GetConfig(c).Handler("prometheus")
if m == nil {
return nil
}
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")
)
// Name returns name of the plugin as seen in Corefile and plugin.cfg
func (p *plug) Name() string { return "refuseany" }