summaryrefslogtreecommitdiff
path: root/netwerk/cache2/CacheHashUtils.cpp
blob: 3dd169c420ac5d22b021d144972e892f505a5f00 (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
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
/* 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/. */

#include "CacheHashUtils.h"

#include "mozilla/BasePrincipal.h"
#include "plstr.h"
#include "mozilla/SHA1.h"

namespace mozilla {
namespace net {

/**
 *  CacheHash::Hash(const char * key, uint32_t initval)
 *
 *  See http://burtleburtle.net/bob/hash/evahash.html for more information
 *  about this hash function.
 *
 *  This algorithm is used to check the data integrity.
 */

static inline void hashmix(uint32_t& a, uint32_t& b, uint32_t& c)
{
  a -= b; a -= c; a ^= (c>>13);
  b -= c; b -= a; b ^= (a<<8);
  c -= a; c -= b; c ^= (b>>13);
  a -= b; a -= c; a ^= (c>>12);
  b -= c; b -= a; b ^= (a<<16);
  c -= a; c -= b; c ^= (b>>5);
  a -= b; a -= c; a ^= (c>>3);
  b -= c; b -= a; b ^= (a<<10);
  c -= a; c -= b; c ^= (b>>15);
}

CacheHash::Hash32_t
CacheHash::Hash(const char *aData, uint32_t aSize, uint32_t aInitval)
{
  const uint8_t *k = reinterpret_cast<const uint8_t*>(aData);
  uint32_t a, b, c, len;

//  length = PL_strlen(key);
  /* Set up the internal state */
  len = aSize;
  a = b = 0x9e3779b9;  /* the golden ratio; an arbitrary value */
  c = aInitval;        /* variable initialization of internal state */

  /*---------------------------------------- handle most of the key */
  while (len >= 12)
  {
    a += k[0] + (uint32_t(k[1])<<8) + (uint32_t(k[2])<<16) + (uint32_t(k[3])<<24);
    b += k[4] + (uint32_t(k[5])<<8) + (uint32_t(k[6])<<16) + (uint32_t(k[7])<<24);
    c += k[8] + (uint32_t(k[9])<<8) + (uint32_t(k[10])<<16) + (uint32_t(k[11])<<24);
    hashmix(a, b, c);
    k += 12; len -= 12;
  }

  /*------------------------------------- handle the last 11 bytes */
  c += aSize;
  switch(len) {              /* all the case statements fall through */
    case 11: c += (uint32_t(k[10])<<24);  [[fallthrough]];
    case 10: c += (uint32_t(k[9])<<16);   [[fallthrough]];
    case 9 : c += (uint32_t(k[8])<<8);    [[fallthrough]];
    /* the low-order byte of c is reserved for the length */
    case 8 : b += (uint32_t(k[7])<<24);   [[fallthrough]];
    case 7 : b += (uint32_t(k[6])<<16);   [[fallthrough]];
    case 6 : b += (uint32_t(k[5])<<8);    [[fallthrough]];
    case 5 : b += k[4];                   [[fallthrough]];
    case 4 : a += (uint32_t(k[3])<<24);   [[fallthrough]];
    case 3 : a += (uint32_t(k[2])<<16);   [[fallthrough]];
    case 2 : a += (uint32_t(k[1])<<8);    [[fallthrough]];
    case 1 : a += k[0];
    /* case 0: nothing left to add */
  }
  hashmix(a, b, c);

  return c;
}

CacheHash::Hash16_t
CacheHash::Hash16(const char *aData, uint32_t aSize, uint32_t aInitval)
{
  Hash32_t hash = Hash(aData, aSize, aInitval);
  return (hash & 0xFFFF);
}

NS_IMPL_ISUPPORTS0(CacheHash)

CacheHash::CacheHash(uint32_t aInitval)
  : mA(0x9e3779b9)
  , mB(0x9e3779b9)
  , mC(aInitval)
  , mPos(0)
  , mBuf(0)
  , mBufPos(0)
  , mLength(0)
  , mFinalized(false)
{}

void
CacheHash::Feed(uint32_t aVal, uint8_t aLen)
{
  switch (mPos) {
  case 0:
    mA += aVal;
    mPos ++;
    break;

  case 1:
    mB += aVal;
    mPos ++;
    break;

  case 2:
    mPos = 0;
    if (aLen == 4) {
      mC += aVal;
      hashmix(mA, mB, mC);
    }
    else {
      mC += aVal << 8;
    }
  }

  mLength += aLen;
}

void
CacheHash::Update(const char *aData, uint32_t aLen)
{
  const uint8_t *data = reinterpret_cast<const uint8_t*>(aData);

  MOZ_ASSERT(!mFinalized);

  if (mBufPos) {
    while (mBufPos != 4 && aLen) {
      mBuf += uint32_t(*data) << 8*mBufPos;
      data++;
      mBufPos++;
      aLen--;
    }

    if (mBufPos == 4) {
      mBufPos = 0;
      Feed(mBuf);
      mBuf = 0;
    }
  }

  if (!aLen)
    return;

  while (aLen >= 4) {
    Feed(data[0] + (uint32_t(data[1]) << 8) + (uint32_t(data[2]) << 16) +
         (uint32_t(data[3]) << 24));
    data += 4;
    aLen -= 4;
  }

  switch (aLen) {
    case 3: mBuf += data[2] << 16;  [[fallthrough]];
    case 2: mBuf += data[1] << 8;   [[fallthrough]];
    case 1: mBuf += data[0];
  }

  mBufPos = aLen;
}

CacheHash::Hash32_t
CacheHash::GetHash()
{
  if (!mFinalized)
  {
    if (mBufPos) {
      Feed(mBuf, mBufPos);
    }
    mC += mLength;
    hashmix(mA, mB, mC);
    mFinalized = true;
  }

  return mC;
}

CacheHash::Hash16_t
CacheHash::GetHash16()
{
  Hash32_t hash = GetHash();
  return (hash & 0xFFFF);
}

OriginAttrsHash
GetOriginAttrsHash(const mozilla::OriginAttributes &aOA)
{
  nsAutoCString suffix;
  aOA.CreateSuffix(suffix);

  SHA1Sum sum;
  SHA1Sum::Hash hash;
  sum.update(suffix.BeginReading(), suffix.Length());
  sum.finish(hash);

  return BigEndian::readUint64(&hash);
}

} // namespace net
} // namespace mozilla