63 lines
1.6 KiB
Go
63 lines
1.6 KiB
Go
package main
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import (
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"fmt"
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"github.com/holoplot/go-avahi"
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"github.com/miekg/dns"
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"github.com/sirupsen/logrus"
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)
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func createDNSReply(logger *logrus.Entry, aserver *avahi.Server, r *dns.Msg) *dns.Msg {
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m := new(dns.Msg)
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m.Compress = false
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switch r.Opcode {
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case dns.OpcodeQuery:
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for _, q := range r.Question {
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switch q.Qtype {
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case dns.TypeA:
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rr, err := avahiToRecord(logger, aserver, q.Name, avahi.ProtoInet, "A")
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if err != nil {
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logger.WithError(err).Error("avahi A lookup failed, skipping query...")
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continue
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}
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m.Answer = append(m.Answer, rr)
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case dns.TypeAAAA:
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rr, err := avahiToRecord(logger, aserver, q.Name, avahi.ProtoInet6, "AAAA")
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if err != nil {
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logger.WithError(err).Error("avahi AAAA lookup failed, skipping query...")
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continue
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}
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m.Answer = append(m.Answer, rr)
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default:
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logger.WithField("type", q.Qtype).Warning("unsupported question")
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}
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}
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default:
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logger.WithField("opcode", r.Opcode).Warning("unsupported opcode")
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}
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return m
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}
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func avahiToRecord(logger *logrus.Entry, aserver *avahi.Server, name string, proto int32, recordType string) (dns.RR, error) {
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logger.WithFields(logrus.Fields{
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"name": name,
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"type": recordType,
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"protocol": proto,
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}).Info("forwarding query to avahi")
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hn, err := aserver.ResolveHostName(avahi.InterfaceUnspec, proto, name, avahi.ProtoUnspec, 0)
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if err != nil {
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return nil, fmt.Errorf("avahi resolve failure: %w", err)
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}
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rr, err := dns.NewRR(fmt.Sprintf("%s %s %s", name, recordType, hn.Address))
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if err != nil {
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return nil, fmt.Errorf("failured to create record: %w", err)
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}
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return rr, err
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}
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