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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