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Return all records for SRV queries

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Return all SRV records and assume the client is smart enough to make the
call.

Signed-off-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Miek Gieben
2020-01-19 08:30:13 +01:00
parent 1a4d55ab3a
commit 63ef6d3d55
5 changed files with 198 additions and 39 deletions
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93
plugin/traffic/traffic.go
View File

@@ -2,6 +2,8 @@ package traffic
import (
"context"
"fmt"
"strconv"
"strings"
"time"
@@ -34,11 +36,12 @@ func (t *Traffic) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
break
}
}
m := new(dns.Msg)
m.SetReply(r)
m.Authoritative = true
addr, port, ok := t.c.Select(cluster)
sockaddr, ok := t.c.Select(cluster)
if !ok {
// ok the cluster (which has potentially extra labels), doesn't exist, but we may have a query for endpoint-0.<cluster>.
// check if we have 2 labels and that the first equals endpoint-0.
@@ -49,25 +52,96 @@ func (t *Traffic) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
return 0, nil
}
labels := dns.SplitDomainName(cluster)
if strings.Compare(labels[0], "endpoint-0") == 0 {
if strings.HasPrefix(labels[0], "endpoint-") {
// recheck if the cluster exist.
addr, port, ok = t.c.Select(labels[1])
cluster = labels[1]
sockaddr, ok = t.c.Select(cluster)
if !ok {
m.Ns = soa(state.Zone)
m.Rcode = dns.RcodeNameError
w.WriteMsg(m)
return 0, nil
}
return t.ServeEndpoint(ctx, state, labels[0], cluster)
}
}
if addr == nil {
if sockaddr == nil {
log.Debugf("No (healthy) endpoints found for %q", cluster)
m.Ns = soa(state.Zone)
w.WriteMsg(m)
return 0, nil
}
switch state.QType() {
case dns.TypeA:
if sockaddr.Address().To4() == nil { // it's an IPv6 address, return nodata in that case.
m.Ns = soa(state.Zone)
break
}
m.Answer = []dns.RR{&dns.A{Hdr: dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 5}, A: sockaddr.Address()}}
case dns.TypeAAAA:
if sockaddr.Address().To4() != nil { // it's an IPv4 address, return nodata in that case.
m.Ns = soa(state.Zone)
break
}
m.Answer = []dns.RR{&dns.AAAA{Hdr: dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: 5}, AAAA: sockaddr.Address()}}
case dns.TypeSRV:
sockaddrs, _ := t.c.All(cluster)
for i, sa := range sockaddrs {
target := fmt.Sprintf("endpoint-%d.%s.%s", i, cluster, state.Zone)
m.Answer = append(m.Answer, &dns.SRV{
Hdr: dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 5},
Priority: 100, Weight: 100, Port: sa.Port(), Target: target})
if sa.Address().To4() == nil {
m.Extra = []dns.RR{&dns.AAAA{Hdr: dns.RR_Header{Name: target, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 5}, AAAA: sa.Address()}}
} else {
m.Extra = []dns.RR{&dns.A{Hdr: dns.RR_Header{Name: target, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 5}, A: sa.Address()}}
}
}
default:
m.Ns = soa(state.Zone)
}
w.WriteMsg(m)
return 0, nil
}
func (t *Traffic) ServeEndpoint(ctx context.Context, state request.Request, endpoint, cluster string) (int, error) {
m := new(dns.Msg)
m.SetReply(state.Req)
m.Authoritative = true
// get endpoint number
i := strings.Index(endpoint, "-")
if i == -1 || i == len(endpoint) {
m.Ns = soa(state.Zone)
m.Rcode = dns.RcodeNameError
state.W.WriteMsg(m)
return 0, nil
}
end := endpoint[i+1:] // +1 to remove '-'
nr, err := strconv.Atoi(end)
if err != nil {
m.Ns = soa(state.Zone)
m.Rcode = dns.RcodeNameError
state.W.WriteMsg(m)
return 0, nil
}
sockaddrs, _ := t.c.All(cluster)
if len(sockaddrs) < nr {
m.Ns = soa(state.Zone)
m.Rcode = dns.RcodeNameError
state.W.WriteMsg(m)
return 0, nil
}
addr := sockaddrs[nr].Address()
switch state.QType() {
case dns.TypeA:
if addr.To4() == nil { // it's an IPv6 address, return nodata in that case.
@@ -82,20 +156,11 @@ func (t *Traffic) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
break
}
m.Answer = []dns.RR{&dns.AAAA{Hdr: dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: 5}, AAAA: addr}}
case dns.TypeSRV:
target := dnsutil.Join("endpoint-0", cluster) + state.Zone
m.Answer = []dns.RR{&dns.SRV{Hdr: dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 5},
Priority: 100, Weight: 100, Port: port, Target: target}}
if addr.To4() == nil {
m.Extra = []dns.RR{&dns.AAAA{Hdr: dns.RR_Header{Name: target, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 5}, AAAA: addr}}
} else {
m.Extra = []dns.RR{&dns.A{Hdr: dns.RR_Header{Name: target, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 5}, A: addr}}
}
default:
m.Ns = soa(state.Zone)
}
w.WriteMsg(m)
state.W.WriteMsg(m)
return 0, nil
}