1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "base/guid.h"
6
7 #include <stddef.h>
8 #include <stdint.h>
9
10 #include "base/rand_util.h"
11 #include "base/strings/string_util.h"
12 #include "base/strings/stringprintf.h"
13
14 namespace base {
15
16 namespace {
17
IsLowerHexDigit(char c)18 bool IsLowerHexDigit(char c) {
19 return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f');
20 }
21
IsValidGUIDInternal(const base::StringPiece & guid,bool strict)22 bool IsValidGUIDInternal(const base::StringPiece& guid, bool strict) {
23 const size_t kGUIDLength = 36U;
24 if (guid.length() != kGUIDLength)
25 return false;
26
27 for (size_t i = 0; i < guid.length(); ++i) {
28 char current = guid[i];
29 if (i == 8 || i == 13 || i == 18 || i == 23) {
30 if (current != '-')
31 return false;
32 } else {
33 if ((strict && !IsLowerHexDigit(current)) || !IsHexDigit(current))
34 return false;
35 }
36 }
37
38 return true;
39 }
40
41 } // namespace
42
GenerateGUID()43 std::string GenerateGUID() {
44 uint64_t sixteen_bytes[2];
45 // Use base::RandBytes instead of crypto::RandBytes, because crypto calls the
46 // base version directly, and to prevent the dependency from base/ to crypto/.
47 base::RandBytes(&sixteen_bytes, sizeof(sixteen_bytes));
48
49 // Set the GUID to version 4 as described in RFC 4122, section 4.4.
50 // The format of GUID version 4 must be xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx,
51 // where y is one of [8, 9, A, B].
52
53 // Clear the version bits and set the version to 4:
54 sixteen_bytes[0] &= 0xffffffff'ffff0fffULL;
55 sixteen_bytes[0] |= 0x00000000'00004000ULL;
56
57 // Set the two most significant bits (bits 6 and 7) of the
58 // clock_seq_hi_and_reserved to zero and one, respectively:
59 sixteen_bytes[1] &= 0x3fffffff'ffffffffULL;
60 sixteen_bytes[1] |= 0x80000000'00000000ULL;
61
62 return RandomDataToGUIDString(sixteen_bytes);
63 }
64
IsValidGUID(const base::StringPiece & guid)65 bool IsValidGUID(const base::StringPiece& guid) {
66 return IsValidGUIDInternal(guid, false /* strict */);
67 }
68
IsValidGUIDOutputString(const base::StringPiece & guid)69 bool IsValidGUIDOutputString(const base::StringPiece& guid) {
70 return IsValidGUIDInternal(guid, true /* strict */);
71 }
72
RandomDataToGUIDString(const uint64_t bytes[2])73 std::string RandomDataToGUIDString(const uint64_t bytes[2]) {
74 return StringPrintf("%08x-%04x-%04x-%04x-%012llx",
75 static_cast<unsigned int>(bytes[0] >> 32),
76 static_cast<unsigned int>((bytes[0] >> 16) & 0x0000ffff),
77 static_cast<unsigned int>(bytes[0] & 0x0000ffff),
78 static_cast<unsigned int>(bytes[1] >> 48),
79 bytes[1] & 0x0000ffff'ffffffffULL);
80 }
81
82 } // namespace base
83