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onkarkundargi72cfd362020-02-27 12:34:37 +05301// 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
22// NewHash returns a new UUID derived from the hash of space concatenated with
23// data generated by h. The hash should be at least 16 byte in length. The
24// first 16 bytes of the hash are used to form the UUID. The version of the
25// UUID will be the lower 4 bits of version. NewHash is used to implement
26// NewMD5 and NewSHA1.
27func NewHash(h hash.Hash, space UUID, data []byte, version int) UUID {
28 h.Reset()
29 h.Write(space[:])
30 h.Write(data)
31 s := h.Sum(nil)
32 var uuid UUID
33 copy(uuid[:], s)
34 uuid[6] = (uuid[6] & 0x0f) | uint8((version&0xf)<<4)
35 uuid[8] = (uuid[8] & 0x3f) | 0x80 // RFC 4122 variant
36 return uuid
37}
38
39// NewMD5 returns a new MD5 (Version 3) UUID based on the
40// supplied name space and data. It is the same as calling:
41//
42// NewHash(md5.New(), space, data, 3)
43func NewMD5(space UUID, data []byte) UUID {
44 return NewHash(md5.New(), space, data, 3)
45}
46
47// NewSHA1 returns a new SHA1 (Version 5) UUID based on the
48// supplied name space and data. It is the same as calling:
49//
50// NewHash(sha1.New(), space, data, 5)
51func NewSHA1(space UUID, data []byte) UUID {
52 return NewHash(sha1.New(), space, data, 5)
53}