1 files changed, 100 insertions, 0 deletions
diff --git a/dhcpv6/option_duid.go b/dhcpv6/option_duid.go
new file mode 100644
index 0000000..1cb5fe6
--- /dev/null
+++ b/dhcpv6/option_duid.go
@@ -0,0 +1,100 @@
+package dhcpv6
+
+import (
+	"encoding/binary"
+	"fmt"
+	"github.com/insomniacslk/dhcp/iana"
+)
+
+type DuidType uint16
+
+const (
+	DUID_LL DuidType = iota
+	DUID_LLT
+	DUID_EN
+)
+
+var DuidTypeToString = map[DuidType]string{
+	DUID_LL:  "DUID-LL",
+	DUID_LLT: "DUID-LLT",
+	DUID_EN:  "DUID-EN",
+}
+
+type Duid struct {
+	Type                 DuidType
+	HwType               iana.HwTypeType // for DUID-LLT and DUID-LL. Ignored otherwise. RFC 826
+	Time                 uint32          // for DUID-LLT. Ignored otherwise
+	LinkLayerAddr        []byte
+	EnterpriseNumber     uint32 // for DUID-EN. Ignored otherwise
+	EnterpriseIdentifier []byte // for DUID-EN. Ignored otherwise
+}
+
+func (d *Duid) Length() int {
+	if d.Type == DUID_LLT || d.Type == DUID_LL {
+		return 8 + len(d.LinkLayerAddr)
+	}
+	if d.Type == DUID_EN {
+		return 6 + len(d.EnterpriseIdentifier)
+	}
+	return 0 // should never happen
+}
+
+func (d *Duid) ToBytes() []byte {
+	if d.Type == DUID_LLT || d.Type == DUID_LL {
+		buf := make([]byte, 8)
+		binary.BigEndian.PutUint16(buf[0:2], uint16(d.Type))
+		binary.BigEndian.PutUint16(buf[2:4], uint16(d.HwType))
+		binary.BigEndian.PutUint32(buf[4:8], d.Time)
+		return append(buf, d.LinkLayerAddr...)
+	} else if d.Type == DUID_EN {
+		buf := make([]byte, 6)
+		binary.BigEndian.PutUint16(buf[0:2], uint16(d.Type))
+		binary.BigEndian.PutUint32(buf[2:6], d.EnterpriseNumber)
+		return append(buf, d.EnterpriseIdentifier...)
+	}
+	return []byte{} // should never happen
+}
+
+func (d *Duid) String() string {
+	dtype := DuidTypeToString[d.Type]
+	if dtype == "" {
+		dtype = "Unknown"
+	}
+	hwtype := iana.HwTypeToString[d.HwType]
+	if hwtype == "" {
+		hwtype = "Unknown"
+	}
+	var hwaddr string
+	if d.HwType == iana.HwTypeEthernet {
+		for _, b := range d.LinkLayerAddr {
+			hwaddr += fmt.Sprintf("%02x:", b)
+		}
+		if len(hwaddr) > 0 && hwaddr[len(hwaddr)-1] == ':' {
+			hwaddr = hwaddr[:len(hwaddr)-1]
+		}
+	}
+	return fmt.Sprintf("DUID{type=%v hwtype=%v hwaddr=%v}", dtype, hwtype, hwaddr)
+}
+
+func DuidFromBytes(data []byte) (*Duid, error) {
+	if len(data) < 2 {
+		return nil, fmt.Errorf("Invalid DUID: shorter than 2 bytes")
+	}
+	d := Duid{}
+	d.Type = DuidType(binary.BigEndian.Uint16(data[0:2]))
+	if d.Type == DUID_LLT || d.Type == DUID_LL {
+		if len(data) < 8 {
+			return nil, fmt.Errorf("Invalid DUID-LL/LLT: shorter than 8 bytes")
+		}
+		d.HwType = iana.HwTypeType(binary.BigEndian.Uint16(data[2:4]))
+		d.Time = binary.BigEndian.Uint32(data[4:8])
+		d.LinkLayerAddr = data[8:]
+	} else if d.Type == DUID_EN {
+		if len(data) < 6 {
+			return nil, fmt.Errorf("Invalid DUID-EN: shorter than 6 bytes")
+		}
+		d.EnterpriseNumber = binary.BigEndian.Uint32(data[2:6])
+		d.EnterpriseIdentifier = data[6:]
+	}
+	return &d, nil
+}