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Simple RFC 2782 support with optional .service tag
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Add support for SRV queries of names matching:
_<service>._<protocol>.[.service][.datacenter]<.domain>
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@sodre
sodre committed Jan 31, 2017
1 parent a64dea8 commit c135c08
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Showing 3 changed files with 102 additions and 74 deletions.
10 changes: 9 additions & 1 deletion command/agent/dns.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -304,12 +304,20 @@ func (d *DNSServer) dispatch(network string, req, resp *dns.Msg) {
// Split into the label parts
labels := dns.SplitDomainName(qName)

// The last label is either "node", "service", "query", or a datacenter name
// The last label is either "node", "service", "query", "_<protocol>", or a datacenter name
PARSE:
n := len(labels)
if n == 0 {
goto INVALID
}

// If this is a SRV query the "service" label is optional, we add it back to use the
// existing code-path.
if req.Question[0].Qtype == dns.TypeSRV && strings.HasPrefix(labels[n-1], "_") {
labels = append(labels, "service")
n = n + 1
}

switch labels[n-1] {
case "service":
if n == 1 {
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164 changes: 92 additions & 72 deletions command/agent/dns_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3393,47 +3393,57 @@ func TestDNS_ServiceLookup_SRV_RFC(t *testing.T) {
t.Fatalf("err: %v", err)
}

m := new(dns.Msg)
m.SetQuestion("_db._master.service.consul.", dns.TypeSRV)

c := new(dns.Client)
addr, _ := srv.agent.config.ClientListener("", srv.agent.config.Ports.DNS)
in, _, err := c.Exchange(m, addr.String())
if err != nil {
t.Fatalf("err: %v", err)
questions := []string{
"_db._master.service.dc1.consul.",
"_db._master.service.consul.",
"_db._master.dc1.consul.",
"_db._master.consul.",
}

if len(in.Answer) != 1 {
t.Fatalf("Bad: %#v", in)
}
for _, question := range questions {
m := new(dns.Msg)
m.SetQuestion(question, dns.TypeSRV)

srvRec, ok := in.Answer[0].(*dns.SRV)
if !ok {
t.Fatalf("Bad: %#v", in.Answer[0])
}
if srvRec.Port != 12345 {
t.Fatalf("Bad: %#v", srvRec)
}
if srvRec.Target != "foo.node.dc1.consul." {
t.Fatalf("Bad: %#v", srvRec)
}
if srvRec.Hdr.Ttl != 0 {
t.Fatalf("Bad: %#v", in.Answer[0])
}
c := new(dns.Client)
addr, _ := srv.agent.config.ClientListener("", srv.agent.config.Ports.DNS)
in, _, err := c.Exchange(m, addr.String())
if err != nil {
t.Fatalf("err: %v", err)
}

aRec, ok := in.Extra[0].(*dns.A)
if !ok {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.Hdr.Name != "foo.node.dc1.consul." {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.A.String() != "127.0.0.1" {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.Hdr.Ttl != 0 {
t.Fatalf("Bad: %#v", in.Extra[0])
if len(in.Answer) != 1 {
t.Fatalf("Bad: %#v", in)
}

srvRec, ok := in.Answer[0].(*dns.SRV)
if !ok {
t.Fatalf("Bad: %#v", in.Answer[0])
}
if srvRec.Port != 12345 {
t.Fatalf("Bad: %#v", srvRec)
}
if srvRec.Target != "foo.node.dc1.consul." {
t.Fatalf("Bad: %#v", srvRec)
}
if srvRec.Hdr.Ttl != 0 {
t.Fatalf("Bad: %#v", in.Answer[0])
}

aRec, ok := in.Extra[0].(*dns.A)
if !ok {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.Hdr.Name != "foo.node.dc1.consul." {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.A.String() != "127.0.0.1" {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.Hdr.Ttl != 0 {
t.Fatalf("Bad: %#v", in.Extra[0])
}
}

}

func TestDNS_ServiceLookup_SRV_RFC_TCP_Default(t *testing.T) {
Expand All @@ -3460,47 +3470,57 @@ func TestDNS_ServiceLookup_SRV_RFC_TCP_Default(t *testing.T) {
t.Fatalf("err: %v", err)
}

m := new(dns.Msg)
m.SetQuestion("_db._tcp.service.consul.", dns.TypeSRV)

c := new(dns.Client)
addr, _ := srv.agent.config.ClientListener("", srv.agent.config.Ports.DNS)
in, _, err := c.Exchange(m, addr.String())
if err != nil {
t.Fatalf("err: %v", err)
questions := []string{
"_db._tcp.service.dc1.consul.",
"_db._tcp.service.consul.",
"_db._tcp.dc1.consul.",
"_db._tcp.consul.",
}

if len(in.Answer) != 1 {
t.Fatalf("Bad: %#v", in)
}
for _, question := range questions {
m := new(dns.Msg)
m.SetQuestion(question, dns.TypeSRV)

srvRec, ok := in.Answer[0].(*dns.SRV)
if !ok {
t.Fatalf("Bad: %#v", in.Answer[0])
}
if srvRec.Port != 12345 {
t.Fatalf("Bad: %#v", srvRec)
}
if srvRec.Target != "foo.node.dc1.consul." {
t.Fatalf("Bad: %#v", srvRec)
}
if srvRec.Hdr.Ttl != 0 {
t.Fatalf("Bad: %#v", in.Answer[0])
}
c := new(dns.Client)
addr, _ := srv.agent.config.ClientListener("", srv.agent.config.Ports.DNS)
in, _, err := c.Exchange(m, addr.String())
if err != nil {
t.Fatalf("err: %v", err)
}

aRec, ok := in.Extra[0].(*dns.A)
if !ok {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.Hdr.Name != "foo.node.dc1.consul." {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.A.String() != "127.0.0.1" {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.Hdr.Ttl != 0 {
t.Fatalf("Bad: %#v", in.Extra[0])
if len(in.Answer) != 1 {
t.Fatalf("Bad: %#v", in)
}

srvRec, ok := in.Answer[0].(*dns.SRV)
if !ok {
t.Fatalf("Bad: %#v", in.Answer[0])
}
if srvRec.Port != 12345 {
t.Fatalf("Bad: %#v", srvRec)
}
if srvRec.Target != "foo.node.dc1.consul." {
t.Fatalf("Bad: %#v", srvRec)
}
if srvRec.Hdr.Ttl != 0 {
t.Fatalf("Bad: %#v", in.Answer[0])
}

aRec, ok := in.Extra[0].(*dns.A)
if !ok {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.Hdr.Name != "foo.node.dc1.consul." {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.A.String() != "127.0.0.1" {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.Hdr.Ttl != 0 {
t.Fatalf("Bad: %#v", in.Extra[0])
}
}

}

func TestDNS_ServiceLookup_FilterACL(t *testing.T) {
Expand Down
2 changes: 1 addition & 1 deletion website/source/docs/agent/dns.html.markdown
View file
Original file line number Diff line number Diff line change
Expand Up @@ -138,7 +138,7 @@ foobar.node.dc1.consul. 0 IN A 10.1.10.12

The format for RFC 2782 SRV lookups is:

_<service>._<protocol>.service[.datacenter][.domain]
_<service>._<protocol>[.service][.datacenter][.domain]

Per [RFC 2782](https://tools.ietf.org/html/rfc2782), SRV queries should use
underscores, `_`, as a prefix to the `service` and `protocol` values in a query to
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