package hosts
import (
"context"
"net"
"github.com/coredns/coredns/plugin"
"github.com/coredns/coredns/plugin/pkg/dnsutil"
"github.com/coredns/coredns/plugin/pkg/fall"
"github.com/coredns/coredns/request"
"github.com/miekg/dns"
)
// Hosts is the plugin handler
type Hosts struct {
Next plugin.Handler
*Hostsfile
Fall fall.F
}
// ServeDNS implements the plugin.Handle interface.
func (h Hosts) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := request.Request{W: w, Req: r}
qname := state.Name()
answers := []dns.RR{}
zone := plugin.Zones(h.Origins).Matches(qname)
if zone == "" {
// PTR zones don't need to be specified in Origins.
if state.QType() != dns.TypePTR {
// if this doesn't match we need to fall through regardless of h.Fallthrough
return plugin.NextOrFailure(h.Name(), h.Next, ctx, w, r)
}
}
switch state.QType() {
case dns.TypePTR:
names := h.LookupStaticAddr(dnsutil.ExtractAddressFromReverse(qname))
if len(names) == 0 {
// If this doesn't match we need to fall through regardless of h.Fallthrough
return plugin.NextOrFailure(h.Name(), h.Next, ctx, w, r)
}
answers = h.ptr(qname, h.options.ttl, names)
case dns.TypeA:
ips := h.LookupStaticHostV4(qname)
answers = a(qname, h.options.ttl, ips)
case dns.TypeAAAA:
ips := h.LookupStaticHostV6(qname)
answers = aaaa(qname, h.options.ttl, ips)
}
// Only on NXDOMAIN we will fallthrough.
if len(answers) == 0 && !h.otherRecordsExist(qname) {
if h.Fall.Through(qname) {
return plugin.NextOrFailure(h.Name(), h.Next, ctx, w, r)
}
// We want to send an NXDOMAIN, but because of /etc/hosts' setup we don't have a SOA, so we make it SERVFAIL
// to at least give an answer back to signals we're having problems resolving this.
return dns.RcodeServerFailure, nil
}
m := new(dns.Msg)
m.SetReply(r)
m.Authoritative = true
m.Answer = answers
w.WriteMsg(m)
return dns.RcodeSuccess, nil
}
func (h Hosts) otherRecordsExist(qname string) bool {
if len(h.LookupStaticHostV4(qname)) > 0 {
return true
}
if len(h.LookupStaticHostV6(qname)) > 0 {
return true
}
return false
}
// Name implements the plugin.Handle interface.
func (h Hosts) Name() string { return "hosts" }
// a takes a slice of net.IPs and returns a slice of A RRs.
func a(zone string, ttl uint32, ips []net.IP) []dns.RR {
answers := make([]dns.RR, len(ips))
for i, ip := range ips {
r := new(dns.A)
r.Hdr = dns.RR_Header{Name: zone, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: ttl}
r.A = ip
answers[i] = r
}
return answers
}
// aaaa takes a slice of net.IPs and returns a slice of AAAA RRs.
func aaaa(zone string, ttl uint32, ips []net.IP) []dns.RR {
answers := make([]dns.RR, len(ips))
for i, ip := range ips {
r := new(dns.AAAA)
r.Hdr = dns.RR_Header{Name: zone, Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: ttl}
r.AAAA = ip
answers[i] = r
}
return answers
}
// ptr takes a slice of host names and filters out the ones that aren't in Origins, if specified, and returns a slice of PTR RRs.
func (h *Hosts) ptr(zone string, ttl uint32, names []string) []dns.RR {
answers := make([]dns.RR, len(names))
for i, n := range names {
r := new(dns.PTR)
r.Hdr = dns.RR_Header{Name: zone, Rrtype: dns.TypePTR, Class: dns.ClassINET, Ttl: ttl}
r.Ptr = dns.Fqdn(n)
answers[i] = r
}
return answers
}
option>
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