3 files changed, 236 insertions, 0 deletions
diff --git a/plugin/dnstap/msg/msg.go b/plugin/dnstap/msg/msg.go
new file mode 100644
index 000000000..07930929e
--- /dev/null
+++ b/plugin/dnstap/msg/msg.go
@@ -0,0 +1,168 @@
+// Package msg helps to build a dnstap Message.
+package msg
+
+import (
+	"errors"
+	"net"
+	"strconv"
+	"time"
+
+	tap "github.com/dnstap/golang-dnstap"
+	"github.com/miekg/dns"
+)
+
+// Builder helps to build Data by being aware of the dnstap plugin configuration.
+type Builder struct {
+	Full bool
+	Data
+}
+
+// AddrMsg parses the info of net.Addr and dns.Msg.
+func (b *Builder) AddrMsg(a net.Addr, m *dns.Msg) (err error) {
+	err = b.RemoteAddr(a)
+	if err != nil {
+		return
+	}
+	return b.Msg(m)
+}
+
+// Msg parses the info of dns.Msg.
+func (b *Builder) Msg(m *dns.Msg) (err error) {
+	if b.Full {
+		err = b.Pack(m)
+	}
+	return
+}
+
+// Data helps to build a dnstap Message.
+// It can be transformed into the actual Message using this package.
+type Data struct {
+	Packed      []byte
+	SocketProto tap.SocketProtocol
+	SocketFam   tap.SocketFamily
+	Address     []byte
+	Port        uint32
+	TimeSec     uint64
+}
+
+// HostPort decodes into Data any string returned by dnsutil.ParseHostPortOrFile.
+func (d *Data) HostPort(addr string) error {
+	ip, port, err := net.SplitHostPort(addr)
+	if err != nil {
+		return err
+	}
+	p, err := strconv.ParseUint(port, 10, 32)
+	if err != nil {
+		return err
+	}
+	d.Port = uint32(p)
+
+	if ip := net.ParseIP(ip); ip != nil {
+		d.Address = []byte(ip)
+		if ip := ip.To4(); ip != nil {
+			d.SocketFam = tap.SocketFamily_INET
+		} else {
+			d.SocketFam = tap.SocketFamily_INET6
+		}
+		return nil
+	}
+	return errors.New("not an ip address")
+}
+
+// RemoteAddr parses the information about the remote address into Data.
+func (d *Data) RemoteAddr(remote net.Addr) error {
+	switch addr := remote.(type) {
+	case *net.TCPAddr:
+		d.Address = addr.IP
+		d.Port = uint32(addr.Port)
+		d.SocketProto = tap.SocketProtocol_TCP
+	case *net.UDPAddr:
+		d.Address = addr.IP
+		d.Port = uint32(addr.Port)
+		d.SocketProto = tap.SocketProtocol_UDP
+	default:
+		return errors.New("unknown remote address type")
+	}
+
+	if a := net.IP(d.Address); a.To4() != nil {
+		d.SocketFam = tap.SocketFamily_INET
+	} else {
+		d.SocketFam = tap.SocketFamily_INET6
+	}
+
+	return nil
+}
+
+// Pack encodes the DNS message into Data.
+func (d *Data) Pack(m *dns.Msg) error {
+	packed, err := m.Pack()
+	if err != nil {
+		return err
+	}
+	d.Packed = packed
+	return nil
+}
+
+// Epoch returns the epoch time in seconds.
+func Epoch() uint64 {
+	return uint64(time.Now().Unix())
+}
+
+// Epoch sets the dnstap message epoch.
+func (d *Data) Epoch() {
+	d.TimeSec = Epoch()
+}
+
+// ToClientResponse transforms Data into a client response message.
+func (d *Data) ToClientResponse() *tap.Message {
+	t := tap.Message_CLIENT_RESPONSE
+	return &tap.Message{
+		Type:            &t,
+		SocketFamily:    &d.SocketFam,
+		SocketProtocol:  &d.SocketProto,
+		ResponseTimeSec: &d.TimeSec,
+		ResponseMessage: d.Packed,
+		QueryAddress:    d.Address,
+		QueryPort:       &d.Port,
+	}
+}
+
+// ToClientQuery transforms Data into a client query message.
+func (d *Data) ToClientQuery() *tap.Message {
+	t := tap.Message_CLIENT_QUERY
+	return &tap.Message{
+		Type:           &t,
+		SocketFamily:   &d.SocketFam,
+		SocketProtocol: &d.SocketProto,
+		QueryTimeSec:   &d.TimeSec,
+		QueryMessage:   d.Packed,
+		QueryAddress:   d.Address,
+		QueryPort:      &d.Port,
+	}
+}
+
+// ToOutsideQuery transforms the data into a forwarder or resolver query message.
+func (d *Data) ToOutsideQuery(t tap.Message_Type) *tap.Message {
+	return &tap.Message{
+		Type:            &t,
+		SocketFamily:    &d.SocketFam,
+		SocketProtocol:  &d.SocketProto,
+		QueryTimeSec:    &d.TimeSec,
+		QueryMessage:    d.Packed,
+		ResponseAddress: d.Address,
+		ResponsePort:    &d.Port,
+	}
+}
+
+// ToOutsideResponse transforms the data into a forwarder or resolver response message.
+func (d *Data) ToOutsideResponse(t tap.Message_Type) *tap.Message {
+	return &tap.Message{
+		Type:            &t,
+		SocketFamily:    &d.SocketFam,
+		SocketProtocol:  &d.SocketProto,
+		ResponseTimeSec: &d.TimeSec,
+		ResponseMessage: d.Packed,
+		ResponseAddress: d.Address,
+		ResponsePort:    &d.Port,
+	}
+}
diff --git a/plugin/dnstap/msg/msg_test.go b/plugin/dnstap/msg/msg_test.go
new file mode 100644
index 000000000..649659a80
--- /dev/null
+++ b/plugin/dnstap/msg/msg_test.go
@@ -0,0 +1,42 @@
+package msg
+
+import (
+	"net"
+	"reflect"
+	"testing"
+
+	"github.com/coredns/coredns/plugin/test"
+	"github.com/coredns/coredns/request"
+
+	tap "github.com/dnstap/golang-dnstap"
+	"github.com/miekg/dns"
+)
+
+func testRequest(t *testing.T, expected Data, r request.Request) {
+	d := Data{}
+	if err := d.RemoteAddr(r.W.RemoteAddr()); err != nil {
+		t.Fail()
+		return
+	}
+	if d.SocketProto != expected.SocketProto ||
+		d.SocketFam != expected.SocketFam ||
+		!reflect.DeepEqual(d.Address, expected.Address) ||
+		d.Port != expected.Port {
+		t.Fatalf("expected: %v, have: %v", expected, d)
+		return
+	}
+}
+func TestRequest(t *testing.T) {
+	testRequest(t, Data{
+		SocketProto: tap.SocketProtocol_UDP,
+		SocketFam:   tap.SocketFamily_INET,
+		Address:     net.ParseIP("10.240.0.1"),
+		Port:        40212,
+	}, testingRequest())
+}
+func testingRequest() request.Request {
+	m := new(dns.Msg)
+	m.SetQuestion("example.com.", dns.TypeA)
+	m.SetEdns0(4097, true)
+	return request.Request{W: &test.ResponseWriter{}, Req: m}
+}
diff --git a/plugin/dnstap/msg/wrapper.go b/plugin/dnstap/msg/wrapper.go
new file mode 100644
index 000000000..a74c604d8
--- /dev/null
+++ b/plugin/dnstap/msg/wrapper.go
@@ -0,0 +1,26 @@
+package msg
+
+import (
+	"fmt"
+
+	lib "github.com/dnstap/golang-dnstap"
+	"github.com/golang/protobuf/proto"
+)
+
+func wrap(m *lib.Message) *lib.Dnstap {
+	t := lib.Dnstap_MESSAGE
+	return &lib.Dnstap{
+		Type:    &t,
+		Message: m,
+	}
+}
+
+// Marshal encodes the message to a binary dnstap payload.
+func Marshal(m *lib.Message) (data []byte, err error) {
+	data, err = proto.Marshal(wrap(m))
+	if err != nil {
+		err = fmt.Errorf("proto: %s", err)
+		return
+	}
+	return
+}