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.
10 #include "base/rand_util.h"
11 #include "base/strings/string_util.h"
12 #include "base/strings/stringprintf.h"
18 template <typename Char>
19 bool IsLowerHexDigit(Char c) {
20 return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f');
23 template <typename StringPieceType>
24 bool IsValidGUIDInternal(StringPieceType guid, bool strict) {
25 using CharType = typename StringPieceType::value_type;
27 const size_t kGUIDLength = 36U;
28 if (guid.length() != kGUIDLength)
31 for (size_t i = 0; i < guid.length(); ++i) {
32 CharType current = guid[i];
33 if (i == 8 || i == 13 || i == 18 || i == 23) {
37 if (strict ? !IsLowerHexDigit(current) : !IsHexDigit(current))
47 std::string GenerateGUID() {
48 uint64_t sixteen_bytes[2];
49 // Use base::RandBytes instead of crypto::RandBytes, because crypto calls the
50 // base version directly, and to prevent the dependency from base/ to crypto/.
51 base::RandBytes(&sixteen_bytes, sizeof(sixteen_bytes));
53 // Set the GUID to version 4 as described in RFC 4122, section 4.4.
54 // The format of GUID version 4 must be xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx,
55 // where y is one of [8, 9, A, B].
57 // Clear the version bits and set the version to 4:
58 sixteen_bytes[0] &= 0xffffffff'ffff0fffULL;
59 sixteen_bytes[0] |= 0x00000000'00004000ULL;
61 // Set the two most significant bits (bits 6 and 7) of the
62 // clock_seq_hi_and_reserved to zero and one, respectively:
63 sixteen_bytes[1] &= 0x3fffffff'ffffffffULL;
64 sixteen_bytes[1] |= 0x80000000'00000000ULL;
66 return RandomDataToGUIDString(sixteen_bytes);
69 bool IsValidGUID(base::StringPiece guid) {
70 return IsValidGUIDInternal(guid, false /* strict */);
73 bool IsValidGUID(base::StringPiece16 guid) {
74 return IsValidGUIDInternal(guid, false /* strict */);
77 bool IsValidGUIDOutputString(base::StringPiece guid) {
78 return IsValidGUIDInternal(guid, true /* strict */);
81 std::string RandomDataToGUIDString(const uint64_t bytes[2]) {
82 return StringPrintf("%08x-%04x-%04x-%04x-%012llx",
83 static_cast<unsigned int>(bytes[0] >> 32),
84 static_cast<unsigned int>((bytes[0] >> 16) & 0x0000ffff),
85 static_cast<unsigned int>(bytes[0] & 0x0000ffff),
86 static_cast<unsigned int>(bytes[1] >> 48),
87 bytes[1] & 0x0000ffff'ffffffffULL);