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
 5package uuid
 6
 7import (
 8	"crypto/md5"
 9	"crypto/sha1"
10	"hash"
11)
12
13// Well known namespace IDs and UUIDs
14var (
15	NameSpaceDNS  = Must(Parse("6ba7b810-9dad-11d1-80b4-00c04fd430c8"))
16	NameSpaceURL  = Must(Parse("6ba7b811-9dad-11d1-80b4-00c04fd430c8"))
17	NameSpaceOID  = Must(Parse("6ba7b812-9dad-11d1-80b4-00c04fd430c8"))
18	NameSpaceX500 = Must(Parse("6ba7b814-9dad-11d1-80b4-00c04fd430c8"))
19	Nil           UUID // empty UUID, all zeros
20
21	// The Max UUID is special form of UUID that is specified to have all 128 bits set to 1.
22	Max = UUID{
23		0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
24		0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
25	}
26)
27
28// NewHash returns a new UUID derived from the hash of space concatenated with
29// data generated by h.  The hash should be at least 16 byte in length.  The
30// first 16 bytes of the hash are used to form the UUID.  The version of the
31// UUID will be the lower 4 bits of version.  NewHash is used to implement
32// NewMD5 and NewSHA1.
33func NewHash(h hash.Hash, space UUID, data []byte, version int) UUID {
34	h.Reset()
35	h.Write(space[:]) //nolint:errcheck
36	h.Write(data)     //nolint:errcheck
37	s := h.Sum(nil)
38	var uuid UUID
39	copy(uuid[:], s)
40	uuid[6] = (uuid[6] & 0x0f) | uint8((version&0xf)<<4)
41	uuid[8] = (uuid[8] & 0x3f) | 0x80 // RFC 4122 variant
42	return uuid
43}
44
45// NewMD5 returns a new MD5 (Version 3) UUID based on the
46// supplied name space and data.  It is the same as calling:
47//
48//  NewHash(md5.New(), space, data, 3)
49func NewMD5(space UUID, data []byte) UUID {
50	return NewHash(md5.New(), space, data, 3)
51}
52
53// NewSHA1 returns a new SHA1 (Version 5) UUID based on the
54// supplied name space and data.  It is the same as calling:
55//
56//  NewHash(sha1.New(), space, data, 5)
57func NewSHA1(space UUID, data []byte) UUID {
58	return NewHash(sha1.New(), space, data, 5)
59}