summaryrefslogtreecommitdiffstats
path: root/xpcom/base/nsUUIDGenerator.cpp
blob: 645b34b87efdc7411cd5e7ae417ee602ae9d460f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#if defined(XP_WIN)
#include <windows.h>
#include <objbase.h>
#elif defined(XP_MACOSX)
#include <CoreFoundation/CoreFoundation.h>
#else
#include <stdlib.h>
#include "prrng.h"
#endif

#include "nsUUIDGenerator.h"

using namespace mozilla;

NS_IMPL_ISUPPORTS(nsUUIDGenerator, nsIUUIDGenerator)

nsUUIDGenerator::nsUUIDGenerator()
  : mLock("nsUUIDGenerator.mLock")
{
}

nsUUIDGenerator::~nsUUIDGenerator()
{
}

nsresult
nsUUIDGenerator::Init()
{
  // We're a service, so we're guaranteed that Init() is not going
  // to be reentered while we're inside Init().

#if !defined(XP_WIN) && !defined(XP_MACOSX) && !defined(HAVE_ARC4RANDOM)
  /* initialize random number generator using NSPR random noise */
  unsigned int seed;

  size_t bytes = 0;
  while (bytes < sizeof(seed)) {
    size_t nbytes = PR_GetRandomNoise(((unsigned char*)&seed) + bytes,
                                      sizeof(seed) - bytes);
    if (nbytes == 0) {
      return NS_ERROR_FAILURE;
    }
    bytes += nbytes;
  }

  /* Initialize a new RNG state, and immediately switch
   * back to the previous one -- we want to use mState
   * only for our own calls to random().
   */
  mSavedState = initstate(seed, mState, sizeof(mState));
  setstate(mSavedState);

  mRBytes = 4;
#ifdef RAND_MAX
  if ((unsigned long)RAND_MAX < 0xffffffffUL) {
    mRBytes = 3;
  }
  if ((unsigned long)RAND_MAX < 0x00ffffffUL) {
    mRBytes = 2;
  }
  if ((unsigned long)RAND_MAX < 0x0000ffffUL) {
    mRBytes = 1;
  }
  if ((unsigned long)RAND_MAX < 0x000000ffUL) {
    return NS_ERROR_FAILURE;
  }
#endif

#endif /* non XP_WIN and non XP_MACOSX and non ARC4RANDOM */

  return NS_OK;
}

NS_IMETHODIMP
nsUUIDGenerator::GenerateUUID(nsID** aRet)
{
  nsID* id = static_cast<nsID*>(moz_xmalloc(sizeof(nsID)));
  if (!id) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  nsresult rv = GenerateUUIDInPlace(id);
  if (NS_FAILED(rv)) {
    free(id);
    return rv;
  }

  *aRet = id;
  return rv;
}

NS_IMETHODIMP
nsUUIDGenerator::GenerateUUIDInPlace(nsID* aId)
{
  // The various code in this method is probably not threadsafe, so lock
  // across the whole method.
  MutexAutoLock lock(mLock);

#if defined(XP_WIN)
  HRESULT hr = CoCreateGuid((GUID*)aId);
  if (FAILED(hr)) {
    return NS_ERROR_FAILURE;
  }
#elif defined(XP_MACOSX)
  CFUUIDRef uuid = CFUUIDCreate(kCFAllocatorDefault);
  if (!uuid) {
    return NS_ERROR_FAILURE;
  }

  CFUUIDBytes bytes = CFUUIDGetUUIDBytes(uuid);
  memcpy(aId, &bytes, sizeof(nsID));

  CFRelease(uuid);
#else /* not windows or OS X; generate randomness using random(). */
  /* XXX we should be saving the return of setstate here and switching
   * back to it; instead, we use the value returned when we called
   * initstate, since older glibc's have broken setstate() return values
   */
#ifndef HAVE_ARC4RANDOM
  setstate(mState);
#endif

#ifdef HAVE_ARC4RANDOM_BUF
  arc4random_buf(aId, sizeof(nsID));
#else /* HAVE_ARC4RANDOM_BUF */
  size_t bytesLeft = sizeof(nsID);
  while (bytesLeft > 0) {
#ifdef HAVE_ARC4RANDOM
    long rval = arc4random();
    const size_t mRBytes = 4;
#else
    long rval = random();
#endif


    uint8_t* src = (uint8_t*)&rval;
    // We want to grab the mRBytes least significant bytes of rval, since
    // mRBytes less than sizeof(rval) means the high bytes are 0.
#ifdef IS_BIG_ENDIAN
    src += sizeof(rval) - mRBytes;
#endif
    uint8_t* dst = ((uint8_t*)aId) + (sizeof(nsID) - bytesLeft);
    size_t toWrite = (bytesLeft < mRBytes ? bytesLeft : mRBytes);
    for (size_t i = 0; i < toWrite; i++) {
      dst[i] = src[i];
    }

    bytesLeft -= toWrite;
  }
#endif /* HAVE_ARC4RANDOM_BUF */

  /* Put in the version */
  aId->m2 &= 0x0fff;
  aId->m2 |= 0x4000;

  /* Put in the variant */
  aId->m3[0] &= 0x3f;
  aId->m3[0] |= 0x80;

#ifndef HAVE_ARC4RANDOM
  /* Restore the previous RNG state */
  setstate(mSavedState);
#endif
#endif

  return NS_OK;
}