90 lines
2.4 KiB
Go
90 lines
2.4 KiB
Go
package cache
|
|
|
|
import (
|
|
"time"
|
|
|
|
"github.com/coredns/coredns/plugin/cache/freq"
|
|
|
|
"github.com/miekg/dns"
|
|
)
|
|
|
|
type item struct {
|
|
Rcode int
|
|
AuthenticatedData bool
|
|
RecursionAvailable bool
|
|
Answer []dns.RR
|
|
Ns []dns.RR
|
|
Extra []dns.RR
|
|
|
|
origTTL uint32
|
|
stored time.Time
|
|
|
|
*freq.Freq
|
|
}
|
|
|
|
func newItem(m *dns.Msg, now time.Time, d time.Duration) *item {
|
|
i := new(item)
|
|
i.Rcode = m.Rcode
|
|
i.AuthenticatedData = m.AuthenticatedData
|
|
i.RecursionAvailable = m.RecursionAvailable
|
|
i.Answer = m.Answer
|
|
i.Ns = m.Ns
|
|
i.Extra = make([]dns.RR, len(m.Extra))
|
|
// Don't copy OPT records as these are hop-by-hop.
|
|
j := 0
|
|
for _, e := range m.Extra {
|
|
if e.Header().Rrtype == dns.TypeOPT {
|
|
continue
|
|
}
|
|
i.Extra[j] = e
|
|
j++
|
|
}
|
|
i.Extra = i.Extra[:j]
|
|
|
|
i.origTTL = uint32(d.Seconds())
|
|
i.stored = now.UTC()
|
|
|
|
i.Freq = new(freq.Freq)
|
|
|
|
return i
|
|
}
|
|
|
|
// toMsg turns i into a message, it tailors the reply to m.
|
|
// The Authoritative bit should be set to 0, but some client stub resolver implementations, most notably,
|
|
// on some legacy systems(e.g. ubuntu 14.04 with glib version 2.20), low-level glibc function `getaddrinfo`
|
|
// useb by Python/Ruby/etc.. will discard answers that do not have this bit set.
|
|
// So we're forced to always set this to 1; regardless if the answer came from the cache or not.
|
|
// On newer systems(e.g. ubuntu 16.04 with glib version 2.23), this issue is resolved.
|
|
// So we may set this bit back to 0 in the future ?
|
|
func (i *item) toMsg(m *dns.Msg, now time.Time, do bool) *dns.Msg {
|
|
m1 := new(dns.Msg)
|
|
m1.SetReply(m)
|
|
|
|
// Set this to true as some DNS clients discard the *entire* packet when it's non-authoritative.
|
|
// This is probably not according to spec, but the bit itself is not super useful as this point, so
|
|
// just set it to true.
|
|
m1.Authoritative = true
|
|
m1.AuthenticatedData = i.AuthenticatedData
|
|
if !do {
|
|
m1.AuthenticatedData = false // when DNSSEC was not wanted, it can't be authenticated data.
|
|
}
|
|
m1.RecursionAvailable = i.RecursionAvailable
|
|
m1.Rcode = i.Rcode
|
|
|
|
m1.Answer = make([]dns.RR, len(i.Answer))
|
|
m1.Ns = make([]dns.RR, len(i.Ns))
|
|
m1.Extra = make([]dns.RR, len(i.Extra))
|
|
|
|
ttl := uint32(i.ttl(now))
|
|
m1.Answer = filterRRSlice(i.Answer, ttl, do, true)
|
|
m1.Ns = filterRRSlice(i.Ns, ttl, do, true)
|
|
m1.Extra = filterRRSlice(i.Extra, ttl, do, true)
|
|
|
|
return m1
|
|
}
|
|
|
|
func (i *item) ttl(now time.Time) int {
|
|
ttl := int(i.origTTL) - int(now.UTC().Sub(i.stored).Seconds())
|
|
return ttl
|
|
}
|