forked from coredns/coredns
/
dnssec.go
128 lines (110 loc) · 3.32 KB
/
dnssec.go
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package dnssec
import (
"time"
"github.com/miekg/coredns/middleware"
"github.com/miekg/coredns/singleflight"
"github.com/miekg/dns"
gcache "github.com/patrickmn/go-cache"
)
type Dnssec struct {
Next middleware.Handler
zones []string
keys []*DNSKEY
inflight *singleflight.Group
cache *gcache.Cache
}
func New(zones []string, keys []*DNSKEY, next middleware.Handler) Dnssec {
return Dnssec{Next: next,
zones: zones,
keys: keys,
cache: gcache.New(defaultDuration, purgeDuration),
inflight: new(singleflight.Group),
}
}
// Sign signs the message m. it takes care of negative or nodata responses. It
// uses NSEC black lies for authenticated denial of existence. Signatures
// creates will be cached for a short while. By default we sign for 8 days,
// starting 3 hours ago.
func (d Dnssec) Sign(state middleware.State, zone string, now time.Time) *dns.Msg {
req := state.Req
mt, _ := middleware.Classify(req) // TODO(miek): need opt record here?
if mt == middleware.Delegation {
return req
}
incep, expir := incepExpir(now)
if mt == middleware.NameError {
if req.Ns[0].Header().Rrtype != dns.TypeSOA || len(req.Ns) > 1 {
return req
}
ttl := req.Ns[0].Header().Ttl
if sigs, err := d.sign(req.Ns, zone, ttl, incep, expir); err == nil {
req.Ns = append(req.Ns, sigs...)
}
if sigs, err := d.nsec(state.Name(), zone, ttl, incep, expir); err == nil {
req.Ns = append(req.Ns, sigs...)
}
if len(req.Ns) > 1 { // actually added nsec and sigs, reset the rcode
req.Rcode = dns.RcodeSuccess
}
return req
}
for _, r := range rrSets(req.Answer) {
ttl := r[0].Header().Ttl
if sigs, err := d.sign(r, zone, ttl, incep, expir); err == nil {
req.Answer = append(req.Answer, sigs...)
}
}
for _, r := range rrSets(req.Ns) {
ttl := r[0].Header().Ttl
if sigs, err := d.sign(r, zone, ttl, incep, expir); err == nil {
req.Ns = append(req.Ns, sigs...)
}
}
for _, r := range rrSets(req.Extra) {
ttl := r[0].Header().Ttl
if sigs, err := d.sign(r, zone, ttl, incep, expir); err == nil {
req.Extra = append(sigs, req.Extra...) // prepend to leave OPT alone
}
}
return req
}
func (d Dnssec) sign(rrs []dns.RR, signerName string, ttl, incep, expir uint32) ([]dns.RR, error) {
k := key(rrs)
sgs, ok := d.get(k)
if ok {
return sgs, nil
}
sigs, err := d.inflight.Do(k, func() (interface{}, error) {
sigs := make([]dns.RR, len(d.keys))
var e error
for i, k := range d.keys {
sig := k.NewRRSIG(signerName, ttl, incep, expir)
e = sig.Sign(k.s, rrs)
sigs[i] = sig
}
d.set(k, sigs)
return sigs, e
})
return sigs.([]dns.RR), err
}
func (d Dnssec) set(key string, sigs []dns.RR) {
// we insert the sigs with a duration that is 24 hours less then the expiration, as these
// sigs have *just* been made the duration is 7 days.
d.cache.Set(key, sigs, eightDays-24*time.Hour)
}
func (d Dnssec) get(key string) ([]dns.RR, bool) {
if s, ok := d.cache.Get(key); ok {
return s.([]dns.RR), true
}
return nil, false
}
func incepExpir(now time.Time) (uint32, uint32) {
incep := uint32(now.Add(-3 * time.Hour).Unix()) // -(2+1) hours, be sure to catch daylight saving time and such
expir := uint32(now.Add(eightDays).Unix()) // sign for 8 days
return incep, expir
}
const (
purgeDuration = 3 * time.Hour
defaultDuration = 24 * time.Hour
eightDays = 8 * 24 * time.Hour
)