1
// Copyright 2016 Google Inc.  All rights reserved.
2
// Use of this source code is governed by a BSD-style
3
// license that can be found in the LICENSE file.
4

5
package uuid
6

7
import (
8
	"encoding/binary"
9
)
10

11
// NewUUID returns a Version 1 UUID based on the current NodeID and clock
12
// sequence, and the current time.  If the NodeID has not been set by SetNodeID
13
// or SetNodeInterface then it will be set automatically.  If the NodeID cannot
14
// be set NewUUID returns nil.  If clock sequence has not been set by
15
// SetClockSequence then it will be set automatically.  If GetTime fails to
16
// return the current NewUUID returns nil and an error.
17
//
18
// In most cases, New should be used.
19
func NewUUID() (UUID, error) {
20
	var uuid UUID
21
	now, seq, err := GetTime()
22
	if err != nil {
23
		return uuid, err
24
	}
25

26
	timeLow := uint32(now & 0xffffffff)
27
	timeMid := uint16((now >> 32) & 0xffff)
28
	timeHi := uint16((now >> 48) & 0x0fff)
29
	timeHi |= 0x1000 // Version 1
30

31
	binary.BigEndian.PutUint32(uuid[0:], timeLow)
32
	binary.BigEndian.PutUint16(uuid[4:], timeMid)
33
	binary.BigEndian.PutUint16(uuid[6:], timeHi)
34
	binary.BigEndian.PutUint16(uuid[8:], seq)
35

36
	nodeMu.Lock()
37
	if nodeID == zeroID {
38
		setNodeInterface("")
39
	}
40
	copy(uuid[10:], nodeID[:])
41
	nodeMu.Unlock()
42

43
	return uuid, nil
44
}
45

46