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package file
import (
"github.com/miekg/coredns/middleware/file/tree"
"github.com/miekg/dns"
)
// Result is the result of a Lookup
type Result int
const (
Success Result = iota
NameError
NoData
ServerFailure
)
// Lookup looks up qname and qtype in the zone, when do is true DNSSEC are included as well.
// Three sets of records are returned, one for the answer, one for authority and one for the additional section.
func (z *Zone) Lookup(qname string, qtype uint16, do bool) ([]dns.RR, []dns.RR, []dns.RR, Result) {
var rr dns.RR
mk, known := dns.TypeToRR[qtype]
if !known {
return nil, nil, nil, ServerFailure
} else {
rr = mk()
}
if qtype == dns.TypeSOA {
return z.lookupSOA(do)
}
// Misuse rr to be a question.
rr.Header().Rrtype = qtype
rr.Header().Name = qname
elem := z.Tree.Get(rr)
if elem == nil {
if elem == nil {
return z.nameError(rr, do)
}
}
rrs := elem.Types(dns.TypeCNAME)
if len(rrs) > 0 { // should only ever be 1 actually; TODO(miek) check for this?
rr.Header().Name = rrs[0].(*dns.CNAME).Target
return z.lookupCNAME(rrs, rr, do)
}
rrs = elem.Types(qtype)
if len(rrs) == 0 {
return z.noData(elem, do)
}
if do {
sigs := elem.Types(dns.TypeRRSIG)
sigs = signatureForSubType(sigs, qtype)
rrs = append(rrs, sigs...)
}
return rrs, nil, nil, Success
}
func (z *Zone) noData(elem *tree.Elem, do bool) ([]dns.RR, []dns.RR, []dns.RR, Result) {
soa, _, _, _ := z.lookupSOA(do)
nsec := z.lookupNSEC(elem, do)
return nil, append(soa, nsec...), nil, Success
}
func (z *Zone) nameError(rr dns.RR, do bool) ([]dns.RR, []dns.RR, []dns.RR, Result) {
// Is there a wildcard?
rr1 := dns.Copy(rr)
rr1.Header().Name = rr.Header().Name
rr1.Header().Rrtype = rr.Header().Rrtype
ce := z.ClosestEncloser(rr1)
rr1.Header().Name = "*." + ce
elem := z.Tree.Get(rr1)
if elem != nil {
ret := elem.Types(rr1.Header().Rrtype) // there can only be one of these (or zero)
switch {
case ret != nil:
if do {
sigs := elem.Types(dns.TypeRRSIG)
sigs = signatureForSubType(sigs, rr.Header().Rrtype)
ret = append(ret, sigs...)
}
ret = wildcardReplace(rr, ce, ret)
return ret, nil, nil, Success
case ret == nil:
// nodata, nsec from the wildcard - type does not exist
// nsec proof that name does not exist
// TODO(miek)
}
}
// name error
ret := []dns.RR{z.SOA}
if do {
ret = append(ret, z.SIG...)
ret = append(ret, z.nameErrorProof(rr)...)
}
return nil, ret, nil, NameError
}
func (z *Zone) lookupSOA(do bool) ([]dns.RR, []dns.RR, []dns.RR, Result) {
if do {
ret := append([]dns.RR{z.SOA}, z.SIG...)
return ret, nil, nil, Success
}
return []dns.RR{z.SOA}, nil, nil, Success
}
// lookupNSEC looks up nsec and sigs.
func (z *Zone) lookupNSEC(elem *tree.Elem, do bool) []dns.RR {
if !do {
return nil
}
nsec := elem.Types(dns.TypeNSEC)
if do {
sigs := elem.Types(dns.TypeRRSIG)
sigs = signatureForSubType(sigs, dns.TypeNSEC)
if len(sigs) > 0 {
nsec = append(nsec, sigs...)
}
}
return nsec
}
func (z *Zone) lookupCNAME(rrs []dns.RR, rr dns.RR, do bool) ([]dns.RR, []dns.RR, []dns.RR, Result) {
elem := z.Tree.Get(rr)
if elem == nil {
return rrs, nil, nil, Success
}
extra := cnameForType(elem.All(), rr.Header().Rrtype)
if do {
sigs := elem.Types(dns.TypeRRSIG)
sigs = signatureForSubType(sigs, rr.Header().Rrtype)
if len(sigs) > 0 {
extra = append(extra, sigs...)
}
}
return rrs, nil, extra, Success
}
func cnameForType(targets []dns.RR, origQtype uint16) []dns.RR {
ret := []dns.RR{}
for _, target := range targets {
if target.Header().Rrtype == origQtype {
ret = append(ret, target)
}
}
return ret
}
// signatureForSubType range through the signature and return the correct
// ones for the subtype.
func signatureForSubType(rrs []dns.RR, subtype uint16) []dns.RR {
sigs := []dns.RR{}
for _, sig := range rrs {
if s, ok := sig.(*dns.RRSIG); ok {
if s.TypeCovered == subtype {
sigs = append(sigs, s)
}
}
}
return sigs
}
// wildcardReplace replaces the first wildcard with label.
func wildcardReplace(rr dns.RR, ce string, rrs []dns.RR) []dns.RR {
// Get how many labels the ce is off from the fullname, this is how much of the
// original rr's '*' we must replace.
labels := dns.CountLabel(rr.Header().Name) - dns.CountLabel(ce) // can not be 0, TODO(miek): check
indexes := dns.Split(rr.Header().Name)
if labels >= len(indexes) {
// TODO(miek): yes then what?
// Is the == right here?
return nil
}
replacement := rr.Header().Name[:indexes[labels]]
// need to copy here, otherwise we change in zone stuff
ret := make([]dns.RR, len(rrs))
for i, r := range rrs {
ret[i] = dns.Copy(r)
ret[i].Header().Name = replacement + r.Header().Name[2:]
}
return ret
}
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