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- // Copyright (C) 2013-2018 by Maxim Bublis <b@codemonkey.ru>
- //
- // Permission is hereby granted, free of charge, to any person obtaining
- // a copy of this software and associated documentation files (the
- // "Software"), to deal in the Software without restriction, including
- // without limitation the rights to use, copy, modify, merge, publish,
- // distribute, sublicense, and/or sell copies of the Software, and to
- // permit persons to whom the Software is furnished to do so, subject to
- // the following conditions:
- //
- // The above copyright notice and this permission notice shall be
- // included in all copies or substantial portions of the Software.
- //
- // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
- // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
- // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
- // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
- // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
- // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- package uuid
- import (
- "crypto/md5"
- "crypto/rand"
- "crypto/sha1"
- "encoding/binary"
- "fmt"
- "hash"
- "io"
- "net"
- "os"
- "sync"
- "time"
- )
- // Difference in 100-nanosecond intervals between
- // UUID epoch (October 15, 1582) and Unix epoch (January 1, 1970).
- const epochStart = 122192928000000000
- type epochFunc func() time.Time
- type hwAddrFunc func() (net.HardwareAddr, error)
- var (
- global = newRFC4122Generator()
- posixUID = uint32(os.Getuid())
- posixGID = uint32(os.Getgid())
- )
- // NewV1 returns UUID based on current timestamp and MAC address.
- func NewV1() (UUID, error) {
- return global.NewV1()
- }
- // NewV2 returns DCE Security UUID based on POSIX UID/GID.
- func NewV2(domain byte) (UUID, error) {
- return global.NewV2(domain)
- }
- // NewV3 returns UUID based on MD5 hash of namespace UUID and name.
- func NewV3(ns UUID, name string) UUID {
- return global.NewV3(ns, name)
- }
- // NewV4 returns random generated UUID.
- func NewV4() (UUID, error) {
- return global.NewV4()
- }
- // NewV5 returns UUID based on SHA-1 hash of namespace UUID and name.
- func NewV5(ns UUID, name string) UUID {
- return global.NewV5(ns, name)
- }
- // Generator provides interface for generating UUIDs.
- type Generator interface {
- NewV1() (UUID, error)
- NewV2(domain byte) (UUID, error)
- NewV3(ns UUID, name string) UUID
- NewV4() (UUID, error)
- NewV5(ns UUID, name string) UUID
- }
- // Default generator implementation.
- type rfc4122Generator struct {
- clockSequenceOnce sync.Once
- hardwareAddrOnce sync.Once
- storageMutex sync.Mutex
- rand io.Reader
- epochFunc epochFunc
- hwAddrFunc hwAddrFunc
- lastTime uint64
- clockSequence uint16
- hardwareAddr [6]byte
- }
- func newRFC4122Generator() Generator {
- return &rfc4122Generator{
- epochFunc: time.Now,
- hwAddrFunc: defaultHWAddrFunc,
- rand: rand.Reader,
- }
- }
- // NewV1 returns UUID based on current timestamp and MAC address.
- func (g *rfc4122Generator) NewV1() (UUID, error) {
- u := UUID{}
- timeNow, clockSeq, err := g.getClockSequence()
- if err != nil {
- return Nil, err
- }
- binary.BigEndian.PutUint32(u[0:], uint32(timeNow))
- binary.BigEndian.PutUint16(u[4:], uint16(timeNow>>32))
- binary.BigEndian.PutUint16(u[6:], uint16(timeNow>>48))
- binary.BigEndian.PutUint16(u[8:], clockSeq)
- hardwareAddr, err := g.getHardwareAddr()
- if err != nil {
- return Nil, err
- }
- copy(u[10:], hardwareAddr)
- u.SetVersion(V1)
- u.SetVariant(VariantRFC4122)
- return u, nil
- }
- // NewV2 returns DCE Security UUID based on POSIX UID/GID.
- func (g *rfc4122Generator) NewV2(domain byte) (UUID, error) {
- u, err := g.NewV1()
- if err != nil {
- return Nil, err
- }
- switch domain {
- case DomainPerson:
- binary.BigEndian.PutUint32(u[:], posixUID)
- case DomainGroup:
- binary.BigEndian.PutUint32(u[:], posixGID)
- }
- u[9] = domain
- u.SetVersion(V2)
- u.SetVariant(VariantRFC4122)
- return u, nil
- }
- // NewV3 returns UUID based on MD5 hash of namespace UUID and name.
- func (g *rfc4122Generator) NewV3(ns UUID, name string) UUID {
- u := newFromHash(md5.New(), ns, name)
- u.SetVersion(V3)
- u.SetVariant(VariantRFC4122)
- return u
- }
- // NewV4 returns random generated UUID.
- func (g *rfc4122Generator) NewV4() (UUID, error) {
- u := UUID{}
- if _, err := io.ReadFull(g.rand, u[:]); err != nil {
- return Nil, err
- }
- u.SetVersion(V4)
- u.SetVariant(VariantRFC4122)
- return u, nil
- }
- // NewV5 returns UUID based on SHA-1 hash of namespace UUID and name.
- func (g *rfc4122Generator) NewV5(ns UUID, name string) UUID {
- u := newFromHash(sha1.New(), ns, name)
- u.SetVersion(V5)
- u.SetVariant(VariantRFC4122)
- return u
- }
- // Returns epoch and clock sequence.
- func (g *rfc4122Generator) getClockSequence() (uint64, uint16, error) {
- var err error
- g.clockSequenceOnce.Do(func() {
- buf := make([]byte, 2)
- if _, err = io.ReadFull(g.rand, buf); err != nil {
- return
- }
- g.clockSequence = binary.BigEndian.Uint16(buf)
- })
- if err != nil {
- return 0, 0, err
- }
- g.storageMutex.Lock()
- defer g.storageMutex.Unlock()
- timeNow := g.getEpoch()
- // Clock didn't change since last UUID generation.
- // Should increase clock sequence.
- if timeNow <= g.lastTime {
- g.clockSequence++
- }
- g.lastTime = timeNow
- return timeNow, g.clockSequence, nil
- }
- // Returns hardware address.
- func (g *rfc4122Generator) getHardwareAddr() ([]byte, error) {
- var err error
- g.hardwareAddrOnce.Do(func() {
- if hwAddr, err := g.hwAddrFunc(); err == nil {
- copy(g.hardwareAddr[:], hwAddr)
- return
- }
- // Initialize hardwareAddr randomly in case
- // of real network interfaces absence.
- if _, err = io.ReadFull(g.rand, g.hardwareAddr[:]); err != nil {
- return
- }
- // Set multicast bit as recommended by RFC 4122
- g.hardwareAddr[0] |= 0x01
- })
- if err != nil {
- return []byte{}, err
- }
- return g.hardwareAddr[:], nil
- }
- // Returns difference in 100-nanosecond intervals between
- // UUID epoch (October 15, 1582) and current time.
- func (g *rfc4122Generator) getEpoch() uint64 {
- return epochStart + uint64(g.epochFunc().UnixNano()/100)
- }
- // Returns UUID based on hashing of namespace UUID and name.
- func newFromHash(h hash.Hash, ns UUID, name string) UUID {
- u := UUID{}
- h.Write(ns[:])
- h.Write([]byte(name))
- copy(u[:], h.Sum(nil))
- return u
- }
- // Returns hardware address.
- func defaultHWAddrFunc() (net.HardwareAddr, error) {
- ifaces, err := net.Interfaces()
- if err != nil {
- return []byte{}, err
- }
- for _, iface := range ifaces {
- if len(iface.HardwareAddr) >= 6 {
- return iface.HardwareAddr, nil
- }
- }
- return []byte{}, fmt.Errorf("uuid: no HW address found")
- }
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