github
/
consul
mirror of https://github.com/hashicorp/consul
1
0
Fork 0
Code Issues Projects Releases Wiki Activity
Browse Source

agent: Fixing DNS CNAME recursion

pull/19/head
Armon Dadgar 11 years ago
parent
60b7fccf02
commit
78e28a84a1
2 changed files with 129 additions and 125 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 115
      command/agent/dns.go
  2. 139
      command/agent/dns_test.go

115
command/agent/dns.go
Unescape View File

@ -16,6 +16,7 @@ const (
testQuery = "_test.consul."
consulDomain = "consul."
maxServiceResponses = 3 // For UDP only
maxRecurseRecords = 3
)
// DNSServer is used to wrap an Agent and expose various
@ -175,7 +176,7 @@ func (d *DNSServer) handleQuery(resp dns.ResponseWriter, req *dns.Msg) {
m := new(dns.Msg)
m.SetReply(req)
m.Authoritative = true
m.RecursionAvailable = true
m.RecursionAvailable = (d.recursor != "")
// Only add the SOA if requested
if req.Question[0].Qtype == dns.TypeSOA {
@ -313,22 +314,14 @@ func (d *DNSServer) nodeLookup(network, datacenter, node string, req, resp *dns.
}
// Add the node record
record := formatNodeRecord(&out.NodeServices.Node, req.Question[0].Name, qType)
if record != nil {
resp.Answer = append(resp.Answer, record)
// Try to recursively resolve the CNAME
if cnRec, ok := record.(*dns.CNAME); ok {
aRecs := d.resolveCNAME(cnRec.Target)
if len(aRecs) > 0 {
resp.Extra = append(resp.Extra, aRecs[0])
}
}
records := d.formatNodeRecord(&out.NodeServices.Node, req.Question[0].Name, qType)
if records != nil {
resp.Answer = append(resp.Answer, records...)
}
}
// formatNodeRecord takes a Node and returns an A, AAAA, or CNAME record
func formatNodeRecord(node *structs.Node, qName string, qType uint16) dns.RR {
func (d *DNSServer) formatNodeRecord(node *structs.Node, qName string, qType uint16) (records []dns.RR) {
// Parse the IP
ip := net.ParseIP(node.Address)
var ipv4 net.IP
@ -337,7 +330,7 @@ func formatNodeRecord(node *structs.Node, qName string, qType uint16) dns.RR {
}
switch {
case ipv4 != nil && (qType == dns.TypeANY || qType == dns.TypeA):
return &dns.A{
return []dns.RR{&dns.A{
Hdr: dns.RR_Header{
Name: qName,
Rrtype: dns.TypeA,
@ -345,10 +338,10 @@ func formatNodeRecord(node *structs.Node, qName string, qType uint16) dns.RR {
Ttl: 0,
},
A: ip,
}
}}
case ip != nil && ipv4 == nil && (qType == dns.TypeANY || qType == dns.TypeAAAA):
return &dns.AAAA{
return []dns.RR{&dns.AAAA{
Hdr: dns.RR_Header{
Name: qName,
Rrtype: dns.TypeAAAA,
@ -356,10 +349,12 @@ func formatNodeRecord(node *structs.Node, qName string, qType uint16) dns.RR {
Ttl: 0,
},
AAAA: ip,
}
}}
case ip == nil && (qType == dns.TypeANY || qType == dns.TypeCNAME):
return &dns.CNAME{
case ip == nil && (qType == dns.TypeANY || qType == dns.TypeCNAME ||
qType == dns.TypeA || qType == dns.TypeAAAA):
// Get the CNAME
cnRec := &dns.CNAME{
Hdr: dns.RR_Header{
Name: qName,
Rrtype: dns.TypeCNAME,
@ -368,9 +363,26 @@ func formatNodeRecord(node *structs.Node, qName string, qType uint16) dns.RR {
},
Target: dns.Fqdn(node.Address),
}
default:
return nil
records = append(records, cnRec)
// Recurse
more := d.resolveCNAME(cnRec.Target)
extra := 0
MORE_REC:
for _, rr := range more {
switch rr.Header().Rrtype {
case dns.TypeA:
fallthrough
case dns.TypeAAAA:
records = append(records, rr)
extra++
if extra == maxRecurseRecords {
break MORE_REC
}
}
}
}
return records
}
// serviceLookup is used to handle a service query
@ -410,12 +422,9 @@ func (d *DNSServer) serviceLookup(network, datacenter, service, tag string, req,
qType := req.Question[0].Qtype
d.serviceNodeRecords(out.Nodes, req, resp)
if qType == dns.TypeANY || qType == dns.TypeSRV {
if qType == dns.TypeSRV {
d.serviceSRVRecords(datacenter, out.Nodes, req, resp)
}
// Cleanup duplicate extra entries
resp.Extra = removeDuplicates(resp.Extra)
}
// filterServiceNodes is used to filter out nodes that are failing
@ -460,17 +469,9 @@ func (d *DNSServer) serviceNodeRecords(nodes structs.CheckServiceNodes, req, res
handled[addr] = struct{}{}
// Add the node record
record := formatNodeRecord(&node.Node, qName, qType)
if record != nil {
resp.Answer = append(resp.Answer, record)
// Try to recursively resolve the CNAME
if cnRec, ok := record.(*dns.CNAME); ok {
aRecs := d.resolveCNAME(cnRec.Target)
if len(aRecs) > 0 {
resp.Extra = append(resp.Extra, aRecs[0])
}
}
records := d.formatNodeRecord(&node.Node, qName, qType)
if records != nil {
resp.Answer = append(resp.Answer, records...)
}
}
}
@ -502,26 +503,10 @@ func (d *DNSServer) serviceSRVRecords(dc string, nodes structs.CheckServiceNodes
}
resp.Answer = append(resp.Answer, srvRec)
// Avoid duplicate extra records, possible if a node has
// the same service on multiple ports, etc.
addr := node.Node.Address
if _, ok := handled[addr]; ok {
continue
}
handled[addr] = struct{}{}
// Add the extra record
record := formatNodeRecord(&node.Node, srvRec.Target, dns.TypeANY)
if record != nil {
resp.Extra = append(resp.Extra, record)
// Try to recursively resolve the CNAME
if cnRec, ok := record.(*dns.CNAME); ok {
aRecs := d.resolveCNAME(cnRec.Target)
if len(aRecs) > 0 {
resp.Extra = append(resp.Extra, aRecs[0])
}
}
records := d.formatNodeRecord(&node.Node, srvRec.Target, dns.TypeANY)
if records != nil {
resp.Extra = append(resp.Extra, records...)
}
}
}
@ -584,23 +569,3 @@ func (d *DNSServer) resolveCNAME(name string) []dns.RR {
// Return all the answers
return r.Answer
}
// removeDuplicates is used to remove the duplicate entries.
// This only deduplicates on the QName and QType
func removeDuplicates(rr []dns.RR) []dns.RR {
handled := make(map[string]struct{})
n := len(rr)
for i := 0; i < n; i++ {
rec := rr[i]
hdr := rec.Header()
key := fmt.Sprintf("%s:%d", hdr.Name, hdr.Rrtype)
if _, ok := handled[key]; ok {
// Remove duplicate
rr[i], rr[n-1] = rr[n-1], nil
n--
i--
}
handled[key] = struct{}{}
}
return rr[:n]
}

139
command/agent/dns_test.go
Unescape View File

@ -190,7 +190,8 @@ func TestDNS_NodeLookup_CNAME(t *testing.T) {
t.Fatalf("err: %v", err)
}
if len(in.Answer) != 1 {
// Should have the CNAME record + a few A records
if len(in.Answer) < 2 {
t.Fatalf("Bad: %#v", in)
}
@ -228,7 +229,7 @@ func TestDNS_ServiceLookup(t *testing.T) {
}
m := new(dns.Msg)
m.SetQuestion("db.service.consul.", dns.TypeANY)
m.SetQuestion("db.service.consul.", dns.TypeSRV)
c := new(dns.Client)
in, _, err := c.Exchange(m, srv.agent.config.DNSAddr)
@ -236,22 +237,14 @@ func TestDNS_ServiceLookup(t *testing.T) {
t.Fatalf("err: %v", err)
}
if len(in.Answer) != 2 {
if len(in.Answer) != 1 {
t.Fatalf("Bad: %#v", in)
}
aRec, ok := in.Answer[0].(*dns.A)
srvRec, ok := in.Answer[0].(*dns.SRV)
if !ok {
t.Fatalf("Bad: %#v", in.Answer[0])
}
if aRec.A.String() != "127.0.0.1" {
t.Fatalf("Bad: %#v", in.Answer[0])
}
srvRec, ok := in.Answer[1].(*dns.SRV)
if !ok {
t.Fatalf("Bad: %#v", in.Answer[1])
}
if srvRec.Port != 12345 {
t.Fatalf("Bad: %#v", srvRec)
}
@ -259,7 +252,7 @@ func TestDNS_ServiceLookup(t *testing.T) {
t.Fatalf("Bad: %#v", srvRec)
}
aRec, ok = in.Extra[0].(*dns.A)
aRec, ok := in.Extra[0].(*dns.A)
if !ok {
t.Fatalf("Bad: %#v", in.Extra[0])
}
@ -334,7 +327,7 @@ func TestDNS_ServiceLookup_Dedup(t *testing.T) {
t.Fatalf("err: %v", err)
}
if len(in.Answer) != 3 {
if len(in.Answer) != 1 {
t.Fatalf("Bad: %#v", in)
}
@ -345,10 +338,78 @@ func TestDNS_ServiceLookup_Dedup(t *testing.T) {
if aRec.A.String() != "127.0.0.1" {
t.Fatalf("Bad: %#v", in.Answer[0])
}
}
func TestDNS_ServiceLookup_Dedup_SRV(t *testing.T) {
dir, srv := makeDNSServer(t)
defer os.RemoveAll(dir)
defer srv.agent.Shutdown()
// Wait for leader
time.Sleep(100 * time.Millisecond)
// Register node
args := &structs.RegisterRequest{
Datacenter: "dc1",
Node: "foo",
Address: "127.0.0.1",
Service: &structs.NodeService{
Service: "db",
Tag: "master",
Port: 12345,
},
}
var out struct{}
if err := srv.agent.RPC("Catalog.Register", args, &out); err != nil {
t.Fatalf("err: %v", err)
}
args = &structs.RegisterRequest{
Datacenter: "dc1",
Node: "foo",
Address: "127.0.0.1",
Service: &structs.NodeService{
ID: "db2",
Service: "db",
Tag: "slave",
Port: 12345,
},
}
if err := srv.agent.RPC("Catalog.Register", args, &out); err != nil {
t.Fatalf("err: %v", err)
}
args = &structs.RegisterRequest{
Datacenter: "dc1",
Node: "foo",
Address: "127.0.0.1",
Service: &structs.NodeService{
ID: "db3",
Service: "db",
Tag: "slave",
Port: 12346,
},
}
if err := srv.agent.RPC("Catalog.Register", args, &out); err != nil {
t.Fatalf("err: %v", err)
}
m := new(dns.Msg)
m.SetQuestion("db.service.consul.", dns.TypeSRV)
c := new(dns.Client)
in, _, err := c.Exchange(m, srv.agent.config.DNSAddr)
if err != nil {
t.Fatalf("err: %v", err)
}
if len(in.Answer) != 2 {
t.Fatalf("Bad: %#v", in)
}
srvRec, ok := in.Answer[1].(*dns.SRV)
srvRec, ok := in.Answer[0].(*dns.SRV)
if !ok {
t.Fatalf("Bad: %#v", in.Answer[1])
t.Fatalf("Bad: %#v", in.Answer[0])
}
if srvRec.Port != 12345 && srvRec.Port != 12346 {
t.Fatalf("Bad: %#v", srvRec)
@ -357,21 +418,21 @@ func TestDNS_ServiceLookup_Dedup(t *testing.T) {
t.Fatalf("Bad: %#v", srvRec)
}
srvRec, ok = in.Answer[2].(*dns.SRV)
srvRec, ok = in.Answer[1].(*dns.SRV)
if !ok {
t.Fatalf("Bad: %#v", in.Answer[1])
}
if srvRec.Port != 12346 && srvRec.Port != 12345 {
t.Fatalf("Bad: %#v", srvRec)
}
if srvRec.Port == in.Answer[1].(*dns.SRV).Port {
if srvRec.Port == in.Answer[0].(*dns.SRV).Port {
t.Fatalf("should be a different port")
}
if srvRec.Target != "foo.node.dc1.consul." {
t.Fatalf("Bad: %#v", srvRec)
}
aRec, ok = in.Extra[0].(*dns.A)
aRec, ok := in.Extra[0].(*dns.A)
if !ok {
t.Fatalf("Bad: %#v", in.Extra[0])
}
@ -507,8 +568,8 @@ func TestDNS_ServiceLookup_Randomize(t *testing.T) {
}
// Response length should be truncated
// We should get an SRV + A record for each response (hence 2x)
if len(in.Answer) != 2*maxServiceResponses {
// We should get an A record for each response
if len(in.Answer) != maxServiceResponses {
t.Fatalf("Bad: %#v", len(in.Answer))
}
@ -564,10 +625,11 @@ func TestDNS_ServiceLookup_CNAME(t *testing.T) {
t.Fatalf("err: %v", err)
}
if len(in.Answer) != 2 {
if len(in.Answer) != 4 {
t.Fatalf("Bad: %#v", in)
}
// Should have google CNAME
cnRec, ok := in.Answer[0].(*dns.CNAME)
if !ok {
t.Fatalf("Bad: %#v", in.Answer[0])
@ -576,33 +638,10 @@ func TestDNS_ServiceLookup_CNAME(t *testing.T) {
t.Fatalf("Bad: %#v", in.Answer[0])
}
srvRec, ok := in.Answer[1].(*dns.SRV)
if !ok {
t.Fatalf("Bad: %#v", in.Answer[1])
}
if srvRec.Port != 80 {
t.Fatalf("Bad: %#v", srvRec)
}
if srvRec.Target != "google.node.dc1.consul." {
t.Fatalf("Bad: %#v", srvRec)
}
aRec, ok := in.Extra[0].(*dns.A)
if !ok {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.Hdr.Name != "www.google.com." {
t.Fatalf("Bad: %#v", in.Extra[0])
}
cnRec, ok = in.Extra[1].(*dns.CNAME)
if !ok {
t.Fatalf("Bad: %#v", in.Extra[1])
}
if cnRec.Hdr.Name != "google.node.dc1.consul." {
t.Fatalf("Bad: %#v", in.Extra[1])
}
if cnRec.Target != "www.google.com." {
t.Fatalf("Bad: %#v", in.Extra[1])
// Check we recursively resolve
for i := 1; i < 4; i++ {
if _, ok := in.Answer[i].(*dns.A); !ok {
t.Fatalf("Bad: %#v", in.Answer[i])
}
}
}

Write Preview
Loading…
Cancel
Save