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package options
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
}
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