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handler.go
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/
handler.go
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package redis
import (
"fmt"
"strings"
"github.com/coredns/coredns/plugin"
"github.com/coredns/coredns/request"
"github.com/miekg/dns"
"golang.org/x/net/context"
)
// ServeDNS implements the plugin.Handler interface.
func (redis *Redis) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := request.Request{W: w, Req: r}
qname := state.Name()
qtype := state.Type()
zone := redis.findZone(qname)
if zone == "" {
return plugin.NextOrFailure(qname, redis.Next, ctx, w, r)
}
z := redis.load(zone)
if z == nil {
return redis.errorResponse(state, zone, dns.RcodeServerFailure, nil)
}
if qtype == "AXFR" {
records := redis.AXFR(z)
ch := make(chan *dns.Envelope)
tr := new(dns.Transfer)
tr.TsigSecret = nil
go func(ch chan *dns.Envelope) {
j, l := 0, 0
for i, r := range records {
l += dns.Len(r)
if l > transferLength {
ch <- &dns.Envelope{RR: records[j:i]}
l = 0
j = i
}
}
if j < len(records) {
ch <- &dns.Envelope{RR: records[j:]}
}
close(ch)
}(ch)
err := tr.Out(w, r, ch)
if err != nil {
fmt.Println(err)
}
w.Hijack()
return dns.RcodeSuccess, nil
}
location := redis.findLocation(qname, z)
if len(location) == 0 { // empty, no results
return plugin.NextOrFailure("forwarding to next", redis.Next, ctx, w, r)
// return redis.errorResponse(state, zone, dns.RcodeNameError, nil)
}
answers := make([]dns.RR, 0, 10)
extras := make([]dns.RR, 0, 10)
record := redis.get(location, z)
switch qtype {
case "A":
// Having a CNAME excludes A records, add cnames when querying for A records
if len(record.CNAME) > 0 {
//println("We have a cname in the record")
answers2 := make([]dns.RR, 0, 10)
extras2 := make([]dns.RR, 0, 10)
answers2, extras2 = redis.CNAME(qname, z, record)
answers = append(answers, answers2...)
extras = append(extras, extras2...)
} else {
answers, extras = redis.A(qname, z, record)
}
case "AAAA":
answers, extras = redis.AAAA(qname, z, record)
case "CNAME":
answers, extras = redis.CNAME(qname, z, record)
if len(answers) == 0 {
return plugin.NextOrFailure("forwarding to next", redis.Next, ctx, w, r)
}
case "TXT":
answers, extras = redis.TXT(qname, z, record)
case "NS":
answers, extras = redis.NS(qname, z, record)
case "MX":
answers, extras = redis.MX(qname, z, record)
case "SRV":
answers, extras = redis.SRV(qname, z, record)
case "SOA":
answers, extras = redis.SOA(qname, z, record)
case "CAA":
answers, extras = redis.CAA(qname, z, record)
default:
return plugin.NextOrFailure("forwarding to next", redis.Next, ctx, w, r)
}
m := new(dns.Msg)
m.SetReply(r)
m.Authoritative, m.RecursionAvailable, m.Compress = true, false, true
m.Answer = append(m.Answer, answers...)
m.Extra = append(m.Extra, extras...)
// If there is a CNAME RR in the answers, solve the alias
if record != nil {
for _, CNAMERecord := range record.CNAME {
var query = strings.TrimSuffix(CNAMERecord.Host, "."+z.Name)
var records *Record
if query == CNAMERecord.Host {
//this is not the correct zone lets load the correct one
qzone := redis.findZone(CNAMERecord.Host)
if qzone == "" {
continue
}
qz := redis.load(qzone)
query = strings.TrimSuffix(CNAMERecord.Host, "."+qz.Name)
records = redis.get(query, qz)
} else {
records = redis.get(query, z)
}
if records == nil {
continue
}
answersN := make([]dns.RR, 0, 10)
extrasN := make([]dns.RR, 0, 10)
answersN, extrasN = redis.A(CNAMERecord.Host, z, records)
m.Answer = append(m.Answer, answersN...)
m.Extra = append(m.Extra, extrasN...)
}
}
state.SizeAndDo(m)
m = state.Scrub(m)
_ = w.WriteMsg(m)
return dns.RcodeSuccess, nil
}
// Name implements the Handler interface.
func (redis *Redis) Name() string { return "redis" }
func (redis *Redis) errorResponse(state request.Request, zone string, rcode int, err error) (int, error) {
m := new(dns.Msg)
m.SetRcode(state.Req, rcode)
m.Authoritative, m.RecursionAvailable, m.Compress = true, false, true
state.SizeAndDo(m)
_ = state.W.WriteMsg(m)
// Return success as the rcode to signal we have written to the client.
return dns.RcodeSuccess, err
}