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package reverse
import (
"net"
"github.com/coredns/coredns/plugin"
"github.com/coredns/coredns/plugin/pkg/dnsutil"
"github.com/coredns/coredns/request"
"github.com/miekg/dns"
"golang.org/x/net/context"
)
// Reverse provides dynamic reverse DNS and the related forward RR.
type Reverse struct {
Next plugin.Handler
Networks networks
Fallthrough bool
}
// ServeDNS implements the plugin.Handler interface.
func (re Reverse) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
var rr dns.RR
state := request.Request{W: w, Req: r}
m := new(dns.Msg)
m.SetReply(r)
m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
switch state.QType() {
case dns.TypePTR:
address := dnsutil.ExtractAddressFromReverse(state.Name())
if address == "" {
// Not an reverse lookup, but can still be an pointer for an domain
break
}
ip := net.ParseIP(address)
// loop through the configured networks
for _, n := range re.Networks {
if n.IPnet.Contains(ip) {
rr = &dns.PTR{
Hdr: dns.RR_Header{Name: state.QName(), Rrtype: dns.TypePTR, Class: dns.ClassINET, Ttl: n.TTL},
Ptr: n.ipToHostname(ip),
}
break
}
}
case dns.TypeA:
for _, n := range re.Networks {
if dns.IsSubDomain(n.Zone, state.Name()) {
// skip if requesting an v4 address and network is not v4
if n.IPnet.IP.To4() == nil {
continue
}
result := n.hostnameToIP(state.Name())
if result != nil {
rr = &dns.A{
Hdr: dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: n.TTL},
A: result,
}
break
}
}
}
case dns.TypeAAAA:
for _, n := range re.Networks {
if dns.IsSubDomain(n.Zone, state.Name()) {
// Do not use To16 which tries to make v4 in v6
if n.IPnet.IP.To4() != nil {
continue
}
result := n.hostnameToIP(state.Name())
if result != nil {
rr = &dns.AAAA{
Hdr: dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: n.TTL},
AAAA: result,
}
break
}
}
}
}
if rr != nil {
m.Answer = append(m.Answer, rr)
state.SizeAndDo(m)
w.WriteMsg(m)
return dns.RcodeSuccess, nil
}
if re.Fallthrough {
return plugin.NextOrFailure(re.Name(), re.Next, ctx, w, r)
}
return dns.RcodeServerFailure, nil
}
// Name implements the Handler interface.
func (re Reverse) Name() string { return "reverse" }
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