mirror of
https://github.com/netbirdio/netbird.git
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e8d82c1bd3
Adding DNS server for client Updated the API with new fields Added custom zone object for peer's DNS resolution
68 lines
1.6 KiB
Go
68 lines
1.6 KiB
Go
package dns
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import (
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"context"
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"errors"
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"github.com/miekg/dns"
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log "github.com/sirupsen/logrus"
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"net"
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"time"
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)
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const defaultUpstreamTimeout = 15 * time.Second
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type upstreamResolver struct {
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parentCTX context.Context
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upstreamClient *dns.Client
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upstreamServers []string
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upstreamTimeout time.Duration
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}
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// ServeDNS handles a DNS request
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func (u *upstreamResolver) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
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log.Tracef("received an upstream question: %#v", r.Question[0])
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select {
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case <-u.parentCTX.Done():
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return
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default:
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}
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for _, upstream := range u.upstreamServers {
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ctx, cancel := context.WithTimeout(u.parentCTX, u.upstreamTimeout)
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rm, t, err := u.upstreamClient.ExchangeContext(ctx, r, upstream)
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cancel()
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if err != nil {
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if err == context.DeadlineExceeded || isTimeout(err) {
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log.Warnf("got an error while connecting to upstream %s, error: %v", upstream, err)
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continue
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}
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log.Errorf("got an error while querying the upstream %s, error: %v", upstream, err)
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return
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}
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log.Tracef("took %s to query the upstream %s", t, upstream)
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err = w.WriteMsg(rm)
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if err != nil {
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log.Errorf("got an error while writing the upstream resolver response, error: %v", err)
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}
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return
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}
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log.Errorf("all queries to the upstream nameservers failed with timeout")
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}
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// isTimeout returns true if the given error is a network timeout error.
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//
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// Copied from k8s.io/apimachinery/pkg/util/net.IsTimeout
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func isTimeout(err error) bool {
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var neterr net.Error
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if errors.As(err, &neterr) {
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return neterr != nil && neterr.Timeout()
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}
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return false
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}
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