fermentord/vendor/github.com/gofrs/uuid/generator.go

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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"
"sync"
"time"
)
// Difference in 100-nanosecond intervals between
// UUID epoch (October 15, 1582) and Unix epoch (January 1, 1970).
const epochStart = 122192928000000000
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// EpochFunc is the function type used to provide the current time.
type EpochFunc func() time.Time
// HWAddrFunc is the function type used to provide hardware (MAC) addresses.
type HWAddrFunc func() (net.HardwareAddr, error)
// DefaultGenerator is the default UUID Generator used by this package.
var DefaultGenerator Generator = NewGen()
// NewV1 returns a UUID based on the current timestamp and MAC address.
func NewV1() (UUID, error) {
return DefaultGenerator.NewV1()
}
// NewV3 returns a UUID based on the MD5 hash of the namespace UUID and name.
func NewV3(ns UUID, name string) UUID {
return DefaultGenerator.NewV3(ns, name)
}
// NewV4 returns a randomly generated UUID.
func NewV4() (UUID, error) {
return DefaultGenerator.NewV4()
}
// NewV5 returns a UUID based on SHA-1 hash of the namespace UUID and name.
func NewV5(ns UUID, name string) UUID {
return DefaultGenerator.NewV5(ns, name)
}
// NewV6 returns a k-sortable UUID based on a timestamp and 48 bits of
// pseudorandom data. The timestamp in a V6 UUID is the same as V1, with the bit
// order being adjusted to allow the UUID to be k-sortable.
//
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// This is implemented based on revision 03 of the Peabody UUID draft, and may
// be subject to change pending further revisions. Until the final specification
// revision is finished, changes required to implement updates to the spec will
// not be considered a breaking change. They will happen as a minor version
// releases until the spec is final.
func NewV6() (UUID, error) {
return DefaultGenerator.NewV6()
}
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// NewV7 returns a k-sortable UUID based on the current millisecond precision
// UNIX epoch and 74 bits of pseudorandom data. It supports single-node batch generation (multiple UUIDs in the same timestamp) with a Monotonic Random counter.
//
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// This is implemented based on revision 04 of the Peabody UUID draft, and may
// be subject to change pending further revisions. Until the final specification
// revision is finished, changes required to implement updates to the spec will
// not be considered a breaking change. They will happen as a minor version
// releases until the spec is final.
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func NewV7() (UUID, error) {
return DefaultGenerator.NewV7()
}
// Generator provides an interface for generating UUIDs.
type Generator interface {
NewV1() (UUID, error)
NewV3(ns UUID, name string) UUID
NewV4() (UUID, error)
NewV5(ns UUID, name string) UUID
NewV6() (UUID, error)
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NewV7() (UUID, error)
}
// Gen is a reference UUID generator based on the specifications laid out in
// RFC-4122 and DCE 1.1: Authentication and Security Services. This type
// satisfies the Generator interface as defined in this package.
//
// For consumers who are generating V1 UUIDs, but don't want to expose the MAC
// address of the node generating the UUIDs, the NewGenWithHWAF() function has been
// provided as a convenience. See the function's documentation for more info.
//
// The authors of this package do not feel that the majority of users will need
// to obfuscate their MAC address, and so we recommend using NewGen() to create
// a new generator.
type Gen struct {
clockSequenceOnce sync.Once
hardwareAddrOnce sync.Once
storageMutex sync.Mutex
rand io.Reader
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epochFunc EpochFunc
hwAddrFunc HWAddrFunc
lastTime uint64
clockSequence uint16
hardwareAddr [6]byte
}
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// GenOption is a function type that can be used to configure a Gen generator.
type GenOption func(*Gen)
// interface check -- build will fail if *Gen doesn't satisfy Generator
var _ Generator = (*Gen)(nil)
// NewGen returns a new instance of Gen with some default values set. Most
// people should use this.
func NewGen() *Gen {
return NewGenWithHWAF(defaultHWAddrFunc)
}
// NewGenWithHWAF builds a new UUID generator with the HWAddrFunc provided. Most
// consumers should use NewGen() instead.
//
// This is used so that consumers can generate their own MAC addresses, for use
// in the generated UUIDs, if there is some concern about exposing the physical
// address of the machine generating the UUID.
//
// The Gen generator will only invoke the HWAddrFunc once, and cache that MAC
// address for all the future UUIDs generated by it. If you'd like to switch the
// MAC address being used, you'll need to create a new generator using this
// function.
func NewGenWithHWAF(hwaf HWAddrFunc) *Gen {
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return NewGenWithOptions(WithHWAddrFunc(hwaf))
}
// NewGenWithOptions returns a new instance of Gen with the options provided.
// Most people should use NewGen() or NewGenWithHWAF() instead.
//
// To customize the generator, you can pass in one or more GenOption functions.
// For example:
//
// gen := NewGenWithOptions(
// WithHWAddrFunc(myHWAddrFunc),
// WithEpochFunc(myEpochFunc),
// WithRandomReader(myRandomReader),
// )
//
// NewGenWithOptions(WithHWAddrFunc(myHWAddrFunc)) is equivalent to calling
// NewGenWithHWAF(myHWAddrFunc)
// NewGenWithOptions() is equivalent to calling NewGen()
func NewGenWithOptions(opts ...GenOption) *Gen {
gen := &Gen{
epochFunc: time.Now,
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hwAddrFunc: defaultHWAddrFunc,
rand: rand.Reader,
}
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for _, opt := range opts {
opt(gen)
}
return gen
}
// WithHWAddrFunc is a GenOption that allows you to provide your own HWAddrFunc
// function.
// When this option is nil, the defaultHWAddrFunc is used.
func WithHWAddrFunc(hwaf HWAddrFunc) GenOption {
return func(gen *Gen) {
if hwaf == nil {
hwaf = defaultHWAddrFunc
}
gen.hwAddrFunc = hwaf
}
}
// WithEpochFunc is a GenOption that allows you to provide your own EpochFunc
// function.
// When this option is nil, time.Now is used.
func WithEpochFunc(epochf EpochFunc) GenOption {
return func(gen *Gen) {
if epochf == nil {
epochf = time.Now
}
gen.epochFunc = epochf
}
}
// WithRandomReader is a GenOption that allows you to provide your own random
// reader.
// When this option is nil, the default rand.Reader is used.
func WithRandomReader(reader io.Reader) GenOption {
return func(gen *Gen) {
if reader == nil {
reader = rand.Reader
}
gen.rand = reader
}
}
// NewV1 returns a UUID based on the current timestamp and MAC address.
func (g *Gen) NewV1() (UUID, error) {
u := UUID{}
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timeNow, clockSeq, err := g.getClockSequence(false)
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
}
// NewV3 returns a UUID based on the MD5 hash of the namespace UUID and name.
func (g *Gen) NewV3(ns UUID, name string) UUID {
u := newFromHash(md5.New(), ns, name)
u.SetVersion(V3)
u.SetVariant(VariantRFC4122)
return u
}
// NewV4 returns a randomly generated UUID.
func (g *Gen) 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 a UUID based on SHA-1 hash of the namespace UUID and name.
func (g *Gen) NewV5(ns UUID, name string) UUID {
u := newFromHash(sha1.New(), ns, name)
u.SetVersion(V5)
u.SetVariant(VariantRFC4122)
return u
}
// NewV6 returns a k-sortable UUID based on a timestamp and 48 bits of
// pseudorandom data. The timestamp in a V6 UUID is the same as V1, with the bit
// order being adjusted to allow the UUID to be k-sortable.
//
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// This is implemented based on revision 03 of the Peabody UUID draft, and may
// be subject to change pending further revisions. Until the final specification
// revision is finished, changes required to implement updates to the spec will
// not be considered a breaking change. They will happen as a minor version
// releases until the spec is final.
func (g *Gen) NewV6() (UUID, error) {
var u UUID
if _, err := io.ReadFull(g.rand, u[10:]); err != nil {
return Nil, err
}
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timeNow, clockSeq, err := g.getClockSequence(false)
if err != nil {
return Nil, err
}
binary.BigEndian.PutUint32(u[0:], uint32(timeNow>>28)) // set time_high
binary.BigEndian.PutUint16(u[4:], uint16(timeNow>>12)) // set time_mid
binary.BigEndian.PutUint16(u[6:], uint16(timeNow&0xfff)) // set time_low (minus four version bits)
binary.BigEndian.PutUint16(u[8:], clockSeq&0x3fff) // set clk_seq_hi_res (minus two variant bits)
u.SetVersion(V6)
u.SetVariant(VariantRFC4122)
return u, nil
}
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// getClockSequence returns the epoch and clock sequence for V1,V6 and V7 UUIDs.
//
// When useUnixTSMs is false, it uses the Coordinated Universal Time (UTC) as a count of 100-
//
// nanosecond intervals since 00:00:00.00, 15 October 1582 (the date of Gregorian reform to the Christian calendar).
func (g *Gen) getClockSequence(useUnixTSMs bool) (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()
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var timeNow uint64
if useUnixTSMs {
timeNow = uint64(g.epochFunc().UnixMilli())
} else {
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
}
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// NewV7 returns a k-sortable UUID based on the current millisecond precision
// UNIX epoch and 74 bits of pseudorandom data.
//
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// This is implemented based on revision 04 of the Peabody UUID draft, and may
// be subject to change pending further revisions. Until the final specification
// revision is finished, changes required to implement updates to the spec will
// not be considered a breaking change. They will happen as a minor version
// releases until the spec is final.
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func (g *Gen) NewV7() (UUID, error) {
var u UUID
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/* https://www.ietf.org/archive/id/draft-peabody-dispatch-new-uuid-format-04.html#name-uuid-version-7
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| unix_ts_ms |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| unix_ts_ms | ver | rand_a |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|var| rand_b |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| rand_b |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ */
ms, clockSeq, err := g.getClockSequence(true)
if err != nil {
return Nil, err
}
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//UUIDv7 features a 48 bit timestamp. First 32bit (4bytes) represents seconds since 1970, followed by 2 bytes for the ms granularity.
u[0] = byte(ms >> 40) //1-6 bytes: big-endian unsigned number of Unix epoch timestamp
u[1] = byte(ms >> 32)
u[2] = byte(ms >> 24)
u[3] = byte(ms >> 16)
u[4] = byte(ms >> 8)
u[5] = byte(ms)
//support batching by using a monotonic pseudo-random sequence
//The 6th byte contains the version and partially rand_a data.
//We will lose the most significant bites from the clockSeq (with SetVersion), but it is ok, we need the least significant that contains the counter to ensure the monotonic property
binary.BigEndian.PutUint16(u[6:8], clockSeq) // set rand_a with clock seq which is random and monotonic
//override first 4bits of u[6].
u.SetVersion(V7)
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//set rand_b 64bits of pseudo-random bits (first 2 will be overridden)
if _, err = io.ReadFull(g.rand, u[8:16]); err != nil {
return Nil, err
}
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//override first 2 bits of byte[8] for the variant
u.SetVariant(VariantRFC4122)
return u, nil
}
// Returns the hardware address.
func (g *Gen) getHardwareAddr() ([]byte, error) {
var err error
g.hardwareAddrOnce.Do(func() {
var hwAddr net.HardwareAddr
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 the difference between UUID epoch (October 15, 1582)
// and current time in 100-nanosecond intervals.
func (g *Gen) getEpoch() uint64 {
return epochStart + uint64(g.epochFunc().UnixNano()/100)
}
// Returns the UUID based on the hashing of the 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
}
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var netInterfaces = net.Interfaces
// Returns the hardware address.
func defaultHWAddrFunc() (net.HardwareAddr, error) {
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ifaces, err := netInterfaces()
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")
}