Create & Init Project...
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244
uuid/g.go
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244
uuid/g.go
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package uuid
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import (
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"crypto/md5"
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"crypto/rand"
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"crypto/sha1"
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"encoding/binary"
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"fmt"
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"hash"
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"io"
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"net"
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"os"
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"sync"
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"time"
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)
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// Difference in 100-nanosecond intervals between
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// UUID epoch (October 15, 1582) and Unix epoch (January 1, 1970).
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const epochStart = 122192928000000000
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type epochFunc func() time.Time
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type hwAddrFunc func() (net.HardwareAddr, error)
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var (
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global = newRFC4122Generator()
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posixUID = uint32(os.Getuid())
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posixGID = uint32(os.Getgid())
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)
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// NewV1 returns UUID based on current timestamp and MAC address.
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func NewV1() (UUID, error) {
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return global.NewV1()
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}
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// NewV2 returns DCE Security UUID based on POSIX UID/GID.
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func NewV2(domain byte) (UUID, error) {
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return global.NewV2(domain)
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}
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// NewV3 returns UUID based on MD5 hash of namespace UUID and name.
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func NewV3(ns UUID, name string) UUID {
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return global.NewV3(ns, name)
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}
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// NewV4 returns random generated UUID.
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func NewV4() (UUID, error) {
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return global.NewV4()
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}
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// NewV5 returns UUID based on SHA-1 hash of namespace UUID and name.
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func NewV5(ns UUID, name string) UUID {
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return global.NewV5(ns, name)
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}
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// Generator provides interface for generating UUIDs.
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type Generator interface {
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NewV1() (UUID, error)
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NewV2(domain byte) (UUID, error)
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NewV3(ns UUID, name string) UUID
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NewV4() (UUID, error)
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NewV5(ns UUID, name string) UUID
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}
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// Default generator implementation.
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type rfc4122Generator struct {
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clockSequenceOnce sync.Once
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hardwareAddrOnce sync.Once
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storageMutex sync.Mutex
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rand io.Reader
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epochFunc epochFunc
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hwAddrFunc hwAddrFunc
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lastTime uint64
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clockSequence uint16
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hardwareAddr [6]byte
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}
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func newRFC4122Generator() Generator {
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return &rfc4122Generator{
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epochFunc: time.Now,
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hwAddrFunc: defaultHWAddrFunc,
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rand: rand.Reader,
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}
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}
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// NewV1 returns UUID based on current timestamp and MAC address.
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func (g *rfc4122Generator) NewV1() (UUID, error) {
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u := UUID{}
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timeNow, clockSeq, err := g.getClockSequence()
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if err != nil {
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return Nil, err
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}
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binary.BigEndian.PutUint32(u[0:], uint32(timeNow))
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binary.BigEndian.PutUint16(u[4:], uint16(timeNow>>32))
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binary.BigEndian.PutUint16(u[6:], uint16(timeNow>>48))
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binary.BigEndian.PutUint16(u[8:], clockSeq)
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hardwareAddr, err := g.getHardwareAddr()
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if err != nil {
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return Nil, err
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}
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copy(u[10:], hardwareAddr)
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u.SetVersion(V1)
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u.SetVariant(VariantRFC4122)
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return u, nil
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}
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// NewV2 returns DCE Security UUID based on POSIX UID/GID.
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func (g *rfc4122Generator) NewV2(domain byte) (UUID, error) {
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u, err := g.NewV1()
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if err != nil {
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return Nil, err
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}
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switch domain {
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case DomainPerson:
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binary.BigEndian.PutUint32(u[:], posixUID)
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case DomainGroup:
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binary.BigEndian.PutUint32(u[:], posixGID)
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}
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u[9] = domain
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u.SetVersion(V2)
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u.SetVariant(VariantRFC4122)
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return u, nil
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}
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// NewV3 returns UUID based on MD5 hash of namespace UUID and name.
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func (g *rfc4122Generator) NewV3(ns UUID, name string) UUID {
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u := newFromHash(md5.New(), ns, name)
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u.SetVersion(V3)
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u.SetVariant(VariantRFC4122)
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return u
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}
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// NewV4 returns random generated UUID.
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func (g *rfc4122Generator) NewV4() (UUID, error) {
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u := UUID{}
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if _, err := g.rand.Read(u[:]); err != nil {
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return Nil, err
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}
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u.SetVersion(V4)
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u.SetVariant(VariantRFC4122)
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return u, nil
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}
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// NewV5 returns UUID based on SHA-1 hash of namespace UUID and name.
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func (g *rfc4122Generator) NewV5(ns UUID, name string) UUID {
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u := newFromHash(sha1.New(), ns, name)
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u.SetVersion(V5)
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u.SetVariant(VariantRFC4122)
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return u
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}
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// Returns epoch and clock sequence.
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func (g *rfc4122Generator) getClockSequence() (uint64, uint16, error) {
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var err error
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g.clockSequenceOnce.Do(func() {
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buf := make([]byte, 2)
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if _, err = g.rand.Read(buf); err != nil {
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return
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}
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g.clockSequence = binary.BigEndian.Uint16(buf)
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})
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if err != nil {
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return 0, 0, err
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}
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g.storageMutex.Lock()
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defer g.storageMutex.Unlock()
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timeNow := g.getEpoch()
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// Clock didn't change since last UUID generation.
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// Should increase clock sequence.
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if timeNow <= g.lastTime {
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g.clockSequence++
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}
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g.lastTime = timeNow
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return timeNow, g.clockSequence, nil
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}
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// Returns hardware address.
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func (g *rfc4122Generator) getHardwareAddr() ([]byte, error) {
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var err error
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g.hardwareAddrOnce.Do(func() {
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if hwAddr, err := g.hwAddrFunc(); err == nil {
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copy(g.hardwareAddr[:], hwAddr)
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return
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}
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// Initialize hardwareAddr randomly in case
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// of real network interfaces absence.
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if _, err = g.rand.Read(g.hardwareAddr[:]); err != nil {
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return
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}
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// Set multicast bit as recommended by RFC 4122
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g.hardwareAddr[0] |= 0x01
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})
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if err != nil {
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return []byte{}, err
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}
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return g.hardwareAddr[:], nil
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}
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// Returns difference in 100-nanosecond intervals between
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// UUID epoch (October 15, 1582) and current time.
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func (g *rfc4122Generator) getEpoch() uint64 {
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return epochStart + uint64(g.epochFunc().UnixNano()/100)
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}
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// Returns UUID based on hashing of namespace UUID and name.
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func newFromHash(h hash.Hash, ns UUID, name string) UUID {
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u := UUID{}
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h.Write(ns[:])
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h.Write([]byte(name))
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copy(u[:], h.Sum(nil))
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return u
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}
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// Returns hardware address.
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func defaultHWAddrFunc() (net.HardwareAddr, error) {
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ifaces, err := net.Interfaces()
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if err != nil {
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return []byte{}, err
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}
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for _, iface := range ifaces {
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if len(iface.HardwareAddr) >= 6 {
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return iface.HardwareAddr, nil
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}
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}
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return []byte{}, fmt.Errorf("uuid: no HW address found")
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}
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129
uuid/uuid.go
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129
uuid/uuid.go
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@ -0,0 +1,129 @@
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package uuid
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import (
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"bytes"
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"encoding/hex"
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)
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// Size of a UUID in bytes.
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const Size = 16
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// UUID representation compliant with specification
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// described in RFC 4122.
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type UUID [Size]byte
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// UUID versions
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const (
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_ byte = iota
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V1
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V2
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V3
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V4
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V5
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)
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// UUID layout variants.
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const (
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VariantNCS byte = iota
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VariantRFC4122
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VariantMicrosoft
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VariantFuture
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)
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// UUID DCE domains.
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const (
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DomainPerson = iota
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DomainGroup
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DomainOrg
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)
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// String parse helpers.
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var (
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urnPrefix = []byte("urn:uuid:")
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byteGroups = []int{8, 4, 4, 4, 12}
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)
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// Nil is special form of UUID that is specified to have all
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// 128 bits set to zero.
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var Nil = UUID{}
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// Equal returns true if u1 and u2 equals, otherwise returns false.
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func Equal(u1 UUID, u2 UUID) bool {
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return bytes.Equal(u1[:], u2[:])
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}
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// Version returns algorithm version used to generate UUID.
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func (u UUID) Version() byte {
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return u[6] >> 4
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}
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// Variant returns UUID layout variant.
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func (u UUID) Variant() byte {
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switch {
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case (u[8] >> 7) == 0x00:
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return VariantNCS
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case (u[8] >> 6) == 0x02:
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return VariantRFC4122
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case (u[8] >> 5) == 0x06:
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return VariantMicrosoft
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case (u[8] >> 5) == 0x07:
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fallthrough
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default:
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return VariantFuture
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}
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}
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// Bytes returns bytes slice representation of UUID.
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func (u UUID) Bytes() []byte {
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return u[:]
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}
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// Returns canonical string representation of UUID:
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// xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
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func (u UUID) String() string {
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buf := make([]byte, 36)
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hex.Encode(buf[0:8], u[0:4])
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buf[8] = '-'
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hex.Encode(buf[9:13], u[4:6])
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buf[13] = '-'
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hex.Encode(buf[14:18], u[6:8])
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buf[18] = '-'
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hex.Encode(buf[19:23], u[8:10])
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buf[23] = '-'
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hex.Encode(buf[24:], u[10:])
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return string(buf)
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}
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// SetVersion sets version bits.
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func (u *UUID) SetVersion(v byte) {
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u[6] = (u[6] & 0x0f) | (v << 4)
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}
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// SetVariant sets variant bits.
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func (u *UUID) SetVariant(v byte) {
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switch v {
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case VariantNCS:
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u[8] = (u[8]&(0xff>>1) | (0x00 << 7))
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case VariantRFC4122:
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u[8] = (u[8]&(0xff>>2) | (0x02 << 6))
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case VariantMicrosoft:
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u[8] = (u[8]&(0xff>>3) | (0x06 << 5))
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case VariantFuture:
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fallthrough
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default:
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u[8] = (u[8]&(0xff>>3) | (0x07 << 5))
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}
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}
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// Must is a helper that wraps a call to a function returning (UUID, error)
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// and panics if the error is non-nil. It is intended for use in variable
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// initializations such as
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// var packageUUID = uuid.Must(uuid.FromString("123e4567-e89b-12d3-a456-426655440000"));
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func Must(u UUID, err error) UUID {
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if err != nil {
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panic(err)
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}
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return u
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}
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