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
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}
54