Add Client Link-Layer Address option for RFC 6939 support.

Signed-off-by: Tom McPhail <tom.mcphail@icloud.com>

6 files changed, 122 insertions, 0 deletions

diff --git a/dhcpv6/dhcpv6relay.go b/dhcpv6/dhcpv6relay.go
index 9c08e00..26d6ed4 100644
--- a/dhcpv6/dhcpv6relay.go
+++ b/dhcpv6/dhcpv6relay.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net"
 
+	"github.com/insomniacslk/dhcp/iana"
 	"github.com/u-root/u-root/pkg/uio"
 )
 
@@ -54,6 +55,19 @@ func (ro RelayOptions) RemoteID() *OptRemoteID {
 	return nil
 }
 
+// ClientLinkLayerAddress returns the Hardware Type and
+// Link Layer Address of the requesting client in this relay message.
+func (ro RelayOptions) ClientLinkLayerAddress() (iana.HWType, net.HardwareAddr) {
+	opt := ro.Options.GetOne(OptionClientLinkLayerAddr)
+	if opt == nil {
+		return 0, nil
+	}
+	if lla, ok := opt.(*optClientLinkLayerAddress); ok {
+		return lla.LinkLayerType, lla.LinkLayerAddress
+	}
+	return 0, nil
+}
+
 // RelayMessage is a DHCPv6 relay agent message as defined by RFC 3315 Section
 // 7.
 type RelayMessage struct {
diff --git a/dhcpv6/modifiers.go b/dhcpv6/modifiers.go
index 96fbf4b..8099795 100644
--- a/dhcpv6/modifiers.go
+++ b/dhcpv6/modifiers.go
@@ -152,3 +152,9 @@ func WithIAPD(iaid [4]byte, prefixes ...*OptIAPrefix) Modifier {
 		}
 	}
 }
+
+// WithClientLinkLayerAddress adds or updates the ClientLinkLayerAddress
+// option with provided HWType and HWAddress on a DHCPv6 packet
+func WithClientLinkLayerAddress(ht iana.HWType, lla net.HardwareAddr) Modifier {
+	return WithOption(OptClientLinkLayerAddress(ht, lla))
+}
diff --git a/dhcpv6/modifiers_test.go b/dhcpv6/modifiers_test.go
index 2354bd0..3c3204d 100644
--- a/dhcpv6/modifiers_test.go
+++ b/dhcpv6/modifiers_test.go
@@ -121,3 +121,16 @@ func TestWithIAPD(t *testing.T) {
 	require.Equal(t, 1, len(opt))
 	require.Equal(t, OptionIAPD, opt[0].Code())
 }
+
+func TestWithClientLinkLayerAddress(t *testing.T) {
+	var d RelayMessage
+	mac, _ := net.ParseMAC("a4:83:e7:e3:df:88")
+	WithClientLinkLayerAddress(iana.HWTypeEthernet, mac)(&d)
+
+	opt := d.Options.GetOne(OptionClientLinkLayerAddr)
+	require.Equal(t, OptionClientLinkLayerAddr, opt.Code())
+
+	llt, lla := d.Options.ClientLinkLayerAddress()
+	require.Equal(t, iana.HWTypeEthernet, llt)
+	require.Equal(t, mac, lla)
+}
diff --git a/dhcpv6/option_clientlinklayeraddress.go b/dhcpv6/option_clientlinklayeraddress.go
new file mode 100644
index 0000000..91d8a23
--- /dev/null
+++ b/dhcpv6/option_clientlinklayeraddress.go
@@ -0,0 +1,47 @@
+package dhcpv6
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/insomniacslk/dhcp/iana"
+	"github.com/u-root/u-root/pkg/uio"
+)
+
+// OptClientLinkLayerAddress implements OptionClientLinkLayerAddr option.
+// https://tools.ietf.org/html/rfc6939
+func OptClientLinkLayerAddress(ht iana.HWType, lla net.HardwareAddr) *optClientLinkLayerAddress {
+	return &optClientLinkLayerAddress{LinkLayerType: ht, LinkLayerAddress: lla}
+}
+
+type optClientLinkLayerAddress struct {
+	LinkLayerType    iana.HWType
+	LinkLayerAddress net.HardwareAddr
+}
+
+// Code returns the option code.
+func (op *optClientLinkLayerAddress) Code() OptionCode {
+	return OptionClientLinkLayerAddr
+}
+
+// ToBytes serializes the option and returns it as a sequence of bytes
+func (op *optClientLinkLayerAddress) ToBytes() []byte {
+	buf := uio.NewBigEndianBuffer(nil)
+	buf.Write16(uint16(op.LinkLayerType))
+	buf.WriteBytes(op.LinkLayerAddress)
+	return buf.Data()
+}
+
+func (op *optClientLinkLayerAddress) String() string {
+	return fmt.Sprintf("ClientLinkLayerAddress: Type=%s LinkLayerAddress=%s", op.LinkLayerType, op.LinkLayerAddress)
+}
+
+// parseOptClientLinkLayerAddress deserializes from bytes
+// to build an optClientLinkLayerAddress structure.
+func parseOptClientLinkLayerAddress(data []byte) (*optClientLinkLayerAddress, error) {
+	var opt optClientLinkLayerAddress
+	buf := uio.NewBigEndianBuffer(data)
+	opt.LinkLayerType = iana.HWType(buf.Read16())
+	opt.LinkLayerAddress = buf.ReadAll()
+	return &opt, buf.FinError()
+}
diff --git a/dhcpv6/option_clientlinklayeraddress_test.go b/dhcpv6/option_clientlinklayeraddress_test.go
new file mode 100644
index 0000000..a25e882
--- /dev/null
+++ b/dhcpv6/option_clientlinklayeraddress_test.go
@@ -0,0 +1,40 @@
+package dhcpv6
+
+import (
+	"bytes"
+	"net"
+	"testing"
+
+	"github.com/insomniacslk/dhcp/iana"
+	"github.com/stretchr/testify/require"
+)
+
+func TestParseOptClientLinkLayerAddress(t *testing.T) {
+	data := []byte{
+		0, 1, // LinkLayerType
+		164, 131, 231, 227, 223, 136,
+	}
+	opt, err := parseOptClientLinkLayerAddress(data)
+
+	require.NoError(t, err)
+	require.Equal(t, OptionClientLinkLayerAddr, opt.Code())
+	require.Equal(t, iana.HWTypeEthernet, opt.LinkLayerType)
+	require.Equal(t, net.HardwareAddr(data[2:]), opt.LinkLayerAddress)
+	require.Equal(t, "ClientLinkLayerAddress: Type=Ethernet LinkLayerAddress=a4:83:e7:e3:df:88", opt.String())
+}
+
+func TestOptClientLinkLayerAddressToBytes(t *testing.T) {
+	mac, _ := net.ParseMAC("a4:83:e7:e3:df:88")
+	opt := optClientLinkLayerAddress{
+		LinkLayerType:    iana.HWTypeEthernet,
+		LinkLayerAddress: mac,
+	}
+	want := []byte{
+		0, 1, // LinkLayerType
+		164, 131, 231, 227, 223, 136,
+	}
+	b := opt.ToBytes()
+	if !bytes.Equal(b, want) {
+		t.Fatalf("opt.ToBytes()=%v, want %v", b, want)
+	}
+}
diff --git a/dhcpv6/options.go b/dhcpv6/options.go
index aefdfc8..a3afde0 100644
--- a/dhcpv6/options.go
+++ b/dhcpv6/options.go
@@ -87,6 +87,8 @@ func ParseOption(code OptionCode, optData []byte) (Option, error) {
 		var o OptNetworkInterfaceID
 		err = o.FromBytes(optData)
 		opt = &o
+	case OptionClientLinkLayerAddr:
+		opt, err = parseOptClientLinkLayerAddress(optData)
 	case OptionDHCPv4Msg:
 		opt, err = ParseOptDHCPv4Msg(optData)
 	case OptionDHCP4oDHCP6Server: