// Copyright (C) 2013-2015 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 provides implementation of Universally Unique Identifier (UUID).
// Supported versions are 1, 3, 4 and 5 (as specified in RFC 4122) and
// version 2 (as specified in DCE 1.1).
package uuid
import (
"bytes"
"crypto/md5"
"crypto/rand"
"crypto/sha1"
"database/sql/driver"
"encoding/binary"
"encoding/hex"
"fmt"
"hash"
"net"
"os"
"sync"
"time"
)
// UUID layout variants.
const (
VariantNCS = iota
VariantRFC4122
VariantMicrosoft
VariantFuture
)
// UUID DCE domains.
const (
DomainPerson = iota
DomainGroup
DomainOrg
)
// Difference in 100-nanosecond intervals between
// UUID epoch (October 15, 1582) and Unix epoch (January 1, 1970).
const epochStart = 122192928000000000
// Used in string method conversion
const dash byte = '-'
// UUID v1/v2 storage.
var (
storageMutex sync.Mutex
storageOnce sync.Once
epochFunc = unixTimeFunc
clockSequence uint16
lastTime uint64
hardwareAddr [6]byte
posixUID = uint32(os.Getuid())
posixGID = uint32(os.Getgid())
)
// String parse helpers.
var (
urnPrefix = []byte("urn:uuid:")
byteGroups = []int{8, 4, 4, 4, 12}
)
func initClockSequence() {
buf := make([]byte, 2)
safeRandom(buf)
clockSequence = binary.BigEndian.Uint16(buf)
}
func initHardwareAddr() {
interfaces, err := net.Interfaces()
if err == nil {
for _, iface := range interfaces {
if len(iface.HardwareAddr) >= 6 {
copy(hardwareAddr[:], iface.HardwareAddr)
return
}
}
}
// Initialize hardwareAddr randomly in case
// of real network interfaces absence
safeRandom(hardwareAddr[:])
// Set multicast bit as recommended in RFC 4122
hardwareAddr[0] |= 0x01
}
func initStorage() {
initClockSequence()
initHardwareAddr()
}
func safeRandom(dest []byte) {
if _, err := rand.Read(dest); err != nil {
panic(err)
}
}
// Returns difference in 100-nanosecond intervals between
// UUID epoch (October 15, 1582) and current time.
// This is default epoch calculation function.
func unixTimeFunc() uint64 {
return epochStart + uint64(time.Now().UnixNano()/100)
}
// UUID representation compliant with specification
// described in RFC 4122.
type UUID [16]byte
// NullUUID can be used with the standard sql package to represent a
// UUID value that can be NULL in the database
type NullUUID struct {
UUID UUID
Valid bool
}
// The nil UUID is special form of UUID that is specified to have all
// 128 bits set to zero.
var Nil = UUID{}
// Predefined namespace UUIDs.
var (
NamespaceDNS, _ = FromString("6ba7b810-9dad-11d1-80b4-00c04fd430c8")
NamespaceURL, _ = FromString("6ba7b811-9dad-11d1-80b4-00c04fd430c8")
NamespaceOID, _ = FromString("6ba7b812-9dad-11d1-80b4-00c04fd430c8")
NamespaceX500, _ = FromString("6ba7b814-9dad-11d1-80b4-00c04fd430c8")
)
// And returns result of binary AND of two UUIDs.
func And(u1 UUID, u2 UUID) UUID {
u := UUID{}
for i := 0; i < 16; i++ {
u[i] = u1[i] & u2[i]
}
return u
}
// Or returns result of binary OR of two UUIDs.
func Or(u1 UUID, u2 UUID) UUID {
u := UUID{}
for i := 0; i < 16; i++ {
u[i] = u1[i] | u2[i]
}
return u
}
// Equal returns true if u1 and u2 equals, otherwise returns false.
func Equal(u1 UUID, u2 UUID) bool {
return bytes.Equal(u1[:], u2[:])
}
// Version returns algorithm version used to generate UUID.
func (u UUID) Version() uint {
return uint(u[6] >> 4)
}
// Variant returns UUID layout variant.
func (u UUID) Variant() uint {
switch {
case (u[8] & 0x80) == 0x00:
return VariantNCS
case (u[8]&0xc0)|0x80 == 0x80:
return VariantRFC4122
case (u[8]&0xe0)|0xc0 == 0xc0:
return VariantMicrosoft
}
return VariantFuture
}
// Bytes returns bytes slice representation of UUID.
func (u UUID) Bytes() []byte {
return u[:]
}
// Returns canonical string representation of UUID:
// xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
func (u UUID) String() string {
buf := make([]byte, 36)
hex.Encode(buf[0:8], u[0:4])
buf[8] = dash
hex.Encode(buf[9:13], u[4:6])
buf[13] = dash
hex.Encode(buf[14:18], u[6:8])
buf[18] = dash
hex.Encode(buf[19:23], u[8:10])
buf[23] = dash
hex.Encode(buf[24:], u[10:])
return string(buf)
}
// SetVersion sets version bits.
func (u *UUID) SetVersion(v byte) {
u[6] = (u[6] & 0x0f) | (v << 4)
}
// SetVariant sets variant bits as described in RFC 4122.
func (u *UUID) SetVariant() {
u[8] = (u[8] & 0xbf) | 0x80
}
// MarshalText implements the encoding.TextMarshaler interface.
// The encoding is the same as returned by String.
func (u UUID) MarshalText() (text []byte, err error) {
text = []byte(u.String())
return
}
// UnmarshalText implements the encoding.TextUnmarshaler interface.
// Following formats are supported:
// "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
// "{6ba7b810-9dad-11d1-80b4-00c04fd430c8}",
// "urn:uuid:6ba7b810-9dad-11d1-80b4-00c04fd430c8"
func (u *UUID) UnmarshalText(text []byte) (err error) {
if len(text) < 32 {
err = fmt.Errorf("uuid: UUID string too short: %s", text)
return
}
t := text[:]
braced := false
if bytes.Equal(t[:9], urnPrefix) {
t = t[9:]
} else if t[0] == '{' {
braced = true
t = t[1:]
}
b := u[:]
for i, byteGroup := range byteGroups {
if i > 0 {
if t[0] != '-' {
err = fmt.Errorf("uuid: invalid string format")
return
}
t = t[1:]
}
if len(t) < byteGroup {
err = fmt.Errorf("uuid: UUID string too short: %s", text)
return
}
if i == 4 && len(t) > byteGroup &&
((braced && t[byteGroup] != '}') || len(t[byteGroup:]) > 1 || !braced) {
err = fmt.Errorf("uuid: UUID string too long: %s", text)
return
}
_, err = hex.Decode(b[:byteGroup/2], t[:byteGroup])
if err != nil {
return
}
t = t[byteGroup:]
b = b[byteGroup/2:]
}
return
}
// MarshalBinary implements the encoding.BinaryMarshaler interface.
func (u UUID) MarshalBinary() (data []byte, err error) {
data = u.Bytes()
return
}
// UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.
// It will return error if the slice isn't 16 bytes long.
func (u *UUID) UnmarshalBinary(data []byte) (err error) {
if len(data) != 16 {
err = fmt.Errorf("uuid: UUID must be exactly 16 bytes long, got %d bytes", len(data))
return
}
copy(u[:], data)
return
}
// Value implements the driver.Valuer interface.
func (u UUID) Value() (driver.Value, error) {
return u.String(), nil
}
// Scan implements the sql.Scanner interface.
// A 16-byte slice is handled by UnmarshalBinary, while
// a longer byte slice or a string is handled by UnmarshalText.
func (u *UUID) Scan(src interface{}) error {
switch src := src.(type) {
case []byte:
if len(src) == 16 {
return u.UnmarshalBinary(src)
}
return u.UnmarshalText(src)
case string:
return u.UnmarshalText([]byte(src))
}
return fmt.Errorf("uuid: cannot convert %T to UUID", src)
}
// Value implements the driver.Valuer interface.
func (u NullUUID) Value() (driver.Value, error) {
if !u.Valid {
return nil, nil
}
// Delegate to UUID Value function
return u.UUID.Value()
}
// Scan implements the sql.Scanner interface.
func (u *NullUUID) Scan(src interface{}) error {
if src == nil {
u.UUID, u.Valid = Nil, false
return nil
}
// Delegate to UUID Scan function
u.Valid = true
return u.UUID.Scan(src)
}
// FromBytes returns UUID converted from raw byte slice input.
// It will return error if the slice isn't 16 bytes long.
func FromBytes(input []byte) (u UUID, err error) {
err = u.UnmarshalBinary(input)
return
}
// FromBytesOrNil returns UUID converted from raw byte slice input.
// Same behavior as FromBytes, but returns a Nil UUID on error.
func FromBytesOrNil(input []byte) UUID {
uuid, err := FromBytes(input)
if err != nil {
return Nil
}
return uuid
}
// FromString returns UUID parsed from string input.
// Input is expected in a form accepted by UnmarshalText.
func FromString(input string) (u UUID, err error) {
err = u.UnmarshalText([]byte(input))
return
}
// FromStringOrNil returns UUID parsed from string input.
// Same behavior as FromString, but returns a Nil UUID on error.
func FromStringOrNil(input string) UUID {
uuid, err := FromString(input)
if err != nil {
return Nil
}
return uuid
}
// Returns UUID v1/v2 storage state.
// Returns epoch timestamp, clock sequence, and hardware address.
func getStorage() (uint64, uint16, []byte) {
storageOnce.Do(initStorage)
storageMutex.Lock()
defer storageMutex.Unlock()
timeNow := epochFunc()
// Clock changed backwards since last UUID generation.
// Should increase clock sequence.
if timeNow <= lastTime {
clockSequence++
}
lastTime = timeNow
return timeNow, clockSequence, hardwareAddr[:]
}
// NewV1 returns UUID based on current timestamp and MAC address.
func NewV1() UUID {
u := UUID{}
timeNow, clockSeq, hardwareAddr := getStorage()
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)
copy(u[10:], hardwareAddr)
u.SetVersion(1)
u.SetVariant()
return u
}
// NewV2 returns DCE Security UUID based on POSIX UID/GID.
func NewV2(domain byte) UUID {
u := UUID{}
timeNow, clockSeq, hardwareAddr := getStorage()
switch domain {
case DomainPerson:
binary.BigEndian.PutUint32(u[0:], posixUID)
case DomainGroup:
binary.BigEndian.PutUint32(u[0:], posixGID)
}
binary.BigEndian.PutUint16(u[4:], uint16(timeNow>>32))
binary.BigEndian.PutUint16(u[6:], uint16(timeNow>>48))
binary.BigEndian.PutUint16(u[8:], clockSeq)
u[9] = domain
copy(u[10:], hardwareAddr)
u.SetVersion(2)
u.SetVariant()
return u
}
// NewV3 returns UUID based on MD5 hash of namespace UUID and name.
func NewV3(ns UUID, name string) UUID {
u := newFromHash(md5.New(), ns, name)
u.SetVersion(3)
u.SetVariant()
return u
}
// NewV4 returns random generated UUID.
func NewV4() UUID {
u := UUID{}
safeRandom(u[:])
u.SetVersion(4)
u.SetVariant()
return u
}
// NewV5 returns UUID based on SHA-1 hash of namespace UUID and name.
func NewV5(ns UUID, name string) UUID {
u := newFromHash(sha1.New(), ns, name)
u.SetVersion(5)
u.SetVariant()
return u
}
// 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
}