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package middleware
import "github.com/miekg/dns"
type MsgType int
const (
Success MsgType = iota
NameError // NXDOMAIN in header, SOA in auth.
NoData // NOERROR in header, SOA in auth.
Delegation // NOERROR in header, NS in auth, optionally fluff in additional (not checked).
OtherError // Don't cache these.
)
// Classify classifies a message, it returns the MessageType.
func Classify(m *dns.Msg) (MsgType, *dns.OPT) {
opt := m.IsEdns0()
if len(m.Answer) > 0 && m.Rcode == dns.RcodeSuccess {
return Success, opt
}
soa := false
ns := 0
for _, r := range m.Ns {
if r.Header().Rrtype == dns.TypeSOA {
soa = true
continue
}
if r.Header().Rrtype == dns.TypeNS {
ns++
}
}
// Check length of different sections, and drop stuff that is just to large? TODO(miek).
if soa && m.Rcode == dns.RcodeSuccess {
return NoData, opt
}
if soa && m.Rcode == dns.RcodeNameError {
return NameError, opt
}
if ns > 0 && ns == len(m.Ns) && m.Rcode == dns.RcodeSuccess {
return Delegation, opt
}
if m.Rcode == dns.RcodeSuccess {
return Success, opt
}
return OtherError, opt
}
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