summaryrefslogtreecommitdiff
path: root/toolkit/components/url-classifier/LookupCacheV4.cpp
blob: a96e4931ac22b57d2ee4964e0c47ee1773cd5de2 (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
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
//* -*- 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/. */

#include "LookupCacheV4.h"
#include "HashStore.h"
#include "mozilla/Unused.h"
#include <string>

// MOZ_LOG=UrlClassifierDbService:5
extern mozilla::LazyLogModule gUrlClassifierDbServiceLog;
#define LOG(args) MOZ_LOG(gUrlClassifierDbServiceLog, mozilla::LogLevel::Debug, args)
#define LOG_ENABLED() MOZ_LOG_TEST(gUrlClassifierDbServiceLog, mozilla::LogLevel::Debug)

#define METADATA_SUFFIX NS_LITERAL_CSTRING(".metadata")

namespace mozilla {
namespace safebrowsing {

const int LookupCacheV4::VER = 4;

// Prefixes coming from updates and VLPrefixSet are both stored in the HashTable
// where the (key, value) pair is a prefix size and a lexicographic-sorted string.
// The difference is prefixes from updates use std:string(to avoid additional copies)
// and prefixes from VLPrefixSet use nsCString.
// This class provides a common interface for the partial update algorithm to make it
// easier to operate on two different kind prefix string map..
class VLPrefixSet
{
public:
  explicit VLPrefixSet(const PrefixStringMap& aMap);
  explicit VLPrefixSet(const TableUpdateV4::PrefixStdStringMap& aMap);

  // This function will merge the prefix map in VLPrefixSet to aPrefixMap.
  void Merge(PrefixStringMap& aPrefixMap);

  // Find the smallest string from the map in VLPrefixSet.
  bool GetSmallestPrefix(nsDependentCSubstring& aOutString);

  // Return the number of prefixes in the map
  uint32_t Count() const { return mCount; }

private:
  // PrefixString structure contains a lexicographic-sorted string with
  // a |pos| variable to indicate which substring we are pointing to right now.
  // |pos| increases each time GetSmallestPrefix finds the smallest string.
  struct PrefixString {
    PrefixString(const nsACString& aStr, uint32_t aSize)
     : pos(0)
     , size(aSize)
    {
      data.Rebind(aStr.BeginReading(), aStr.Length());
    }

    const char* get() {
      return pos < data.Length() ? data.BeginReading() + pos : nullptr;
    }
    void next() { pos += size; }
    uint32_t remaining() { return data.Length() - pos; }

    nsDependentCSubstring data;
    uint32_t pos;
    uint32_t size;
  };

  nsClassHashtable<nsUint32HashKey, PrefixString> mMap;
  uint32_t mCount;
};

nsresult
LookupCacheV4::Init()
{
  mVLPrefixSet = new VariableLengthPrefixSet();
  nsresult rv = mVLPrefixSet->Init(mTableName);
  NS_ENSURE_SUCCESS(rv, rv);

  return NS_OK;
}

nsresult
LookupCacheV4::Has(const Completion& aCompletion,
                   bool* aHas, bool* aComplete)
{
  *aHas = false;

  uint32_t length = 0;
  nsDependentCSubstring fullhash;
  fullhash.Rebind((const char *)aCompletion.buf, COMPLETE_SIZE);

  nsresult rv = mVLPrefixSet->Matches(fullhash, &length);
  NS_ENSURE_SUCCESS(rv, rv);

  *aHas = length >= PREFIX_SIZE;
  *aComplete = length == COMPLETE_SIZE;

  if (LOG_ENABLED()) {
    uint32_t prefix = aCompletion.ToUint32();
    LOG(("Probe in V4 %s: %X, found %d, complete %d", mTableName.get(),
          prefix, *aHas, *aComplete));
  }

  return NS_OK;
}

nsresult
LookupCacheV4::Build(PrefixStringMap& aPrefixMap)
{
  return mVLPrefixSet->SetPrefixes(aPrefixMap);
}

nsresult
LookupCacheV4::GetPrefixes(PrefixStringMap& aPrefixMap)
{
  return mVLPrefixSet->GetPrefixes(aPrefixMap);
}

nsresult
LookupCacheV4::ClearPrefixes()
{
  // Clear by seting a empty map
  PrefixStringMap map;
  return mVLPrefixSet->SetPrefixes(map);
}

nsresult
LookupCacheV4::StoreToFile(nsIFile* aFile)
{
  return mVLPrefixSet->StoreToFile(aFile);
}

nsresult
LookupCacheV4::LoadFromFile(nsIFile* aFile)
{
  nsresult rv = mVLPrefixSet->LoadFromFile(aFile);
  if (NS_FAILED(rv)) {
    return rv;
  }

  nsCString state, checksum;
  rv = LoadMetadata(state, checksum);
  if (NS_FAILED(rv)) {
    return rv;
  }

  rv = VerifyChecksum(checksum);
  return rv;
}

size_t
LookupCacheV4::SizeOfPrefixSet()
{
  return mVLPrefixSet->SizeOfIncludingThis(moz_malloc_size_of);
}

static void
AppendPrefixToMap(PrefixStringMap& prefixes, nsDependentCSubstring& prefix)
{
  if (!prefix.Length()) {
    return;
  }

  nsCString* prefixString = prefixes.LookupOrAdd(prefix.Length());
  prefixString->Append(prefix.BeginReading(), prefix.Length());
}

// Read prefix into a buffer and also update the hash which
// keeps track of the checksum
static void
UpdateChecksum(nsICryptoHash* aCrypto, const nsACString& aPrefix)
{
  MOZ_ASSERT(aCrypto);
  aCrypto->Update(reinterpret_cast<uint8_t*>(const_cast<char*>(
                  aPrefix.BeginReading())),
                  aPrefix.Length());
}

// Please see https://bug1287058.bmoattachments.org/attachment.cgi?id=8795366
// for detail about partial update algorithm.
nsresult
LookupCacheV4::ApplyUpdate(TableUpdateV4* aTableUpdate,
                           PrefixStringMap& aInputMap,
                           PrefixStringMap& aOutputMap)
{
  MOZ_ASSERT(aOutputMap.IsEmpty());

  nsCOMPtr<nsICryptoHash> crypto;
  nsresult rv = InitCrypto(crypto);
  if (NS_FAILED(rv)) {
    return rv;
  }

  // oldPSet contains prefixes we already have or we just merged last round.
  // addPSet contains prefixes stored in tableUpdate which should be merged with oldPSet.
  VLPrefixSet oldPSet(aInputMap);
  VLPrefixSet addPSet(aTableUpdate->Prefixes());

  // RemovalIndiceArray is a sorted integer array indicating the index of prefix we should
  // remove from the old prefix set(according to lexigraphic order).
  // |removalIndex| is the current index of RemovalIndiceArray.
  // |numOldPrefixPicked| is used to record how many prefixes we picked from the old map.
  TableUpdateV4::RemovalIndiceArray& removalArray = aTableUpdate->RemovalIndices();
  uint32_t removalIndex = 0;
  int32_t numOldPrefixPicked = -1;

  nsDependentCSubstring smallestOldPrefix;
  nsDependentCSubstring smallestAddPrefix;

  bool isOldMapEmpty = false, isAddMapEmpty = false;

  // This is used to avoid infinite loop for partial update algorithm.
  // The maximum loops will be the number of old prefixes plus the number of add prefixes.
  int32_t index = oldPSet.Count() + addPSet.Count() + 1;
  for(;index > 0; index--) {
    // Get smallest prefix from the old prefix set if we don't have one
    if (smallestOldPrefix.IsEmpty() && !isOldMapEmpty) {
      isOldMapEmpty = !oldPSet.GetSmallestPrefix(smallestOldPrefix);
    }

    // Get smallest prefix from add prefix set if we don't have one
    if (smallestAddPrefix.IsEmpty() && !isAddMapEmpty) {
      isAddMapEmpty = !addPSet.GetSmallestPrefix(smallestAddPrefix);
    }

    bool pickOld;

    // If both prefix sets are not empty, then compare to find the smaller one.
    if (!isOldMapEmpty && !isAddMapEmpty) {
      if (smallestOldPrefix == smallestAddPrefix) {
        LOG(("Add prefix should not exist in the original prefix set."));
        return NS_ERROR_FAILURE;
      }

      // Compare the smallest string in old prefix set and add prefix set,
      // merge the smaller one into new map to ensure merged string still
      // follows lexigraphic order.
      pickOld = smallestOldPrefix < smallestAddPrefix;
    } else if (!isOldMapEmpty && isAddMapEmpty) {
      pickOld = true;
    } else if (isOldMapEmpty && !isAddMapEmpty) {
      pickOld = false;
    // If both maps are empty, then partial update is complete.
    } else {
      break;
    }

    if (pickOld) {
      numOldPrefixPicked++;

      // If the number of picks from old map matches the removalIndex, then this prefix
      // will be removed by not merging it to new map.
      if (removalIndex < removalArray.Length() &&
          numOldPrefixPicked == removalArray[removalIndex]) {
        removalIndex++;
      } else {
        AppendPrefixToMap(aOutputMap, smallestOldPrefix);
        UpdateChecksum(crypto, smallestOldPrefix);
      }
      smallestOldPrefix.SetLength(0);
    } else {
      AppendPrefixToMap(aOutputMap, smallestAddPrefix);
      UpdateChecksum(crypto, smallestAddPrefix);

      smallestAddPrefix.SetLength(0);
    }
  }

  // We expect index will be greater to 0 because max number of runs will be
  // the number of original prefix plus add prefix.
  if (index <= 0) {
    LOG(("There are still prefixes remaining after reaching maximum runs."));
    return NS_ERROR_FAILURE;
  }

  if (removalIndex < removalArray.Length()) {
    LOG(("There are still prefixes to remove after exhausting the old PrefixSet."));
    return NS_ERROR_FAILURE;
  }

  nsAutoCString checksum;
  crypto->Finish(false, checksum);
  if (aTableUpdate->Checksum().IsEmpty()) {
    LOG(("Update checksum missing."));

    // Generate our own checksum to tableUpdate to ensure there is always
    // checksum in .metadata
    std::string stdChecksum(checksum.BeginReading(), checksum.Length());
    aTableUpdate->NewChecksum(stdChecksum);

  } else if (aTableUpdate->Checksum() != checksum){
    LOG(("Checksum mismatch after applying partial update"));
    return NS_ERROR_FAILURE;
  }

  return NS_OK;
}

nsresult
LookupCacheV4::InitCrypto(nsCOMPtr<nsICryptoHash>& aCrypto)
{
  nsresult rv;
  aCrypto = do_CreateInstance(NS_CRYPTO_HASH_CONTRACTID, &rv);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  rv = aCrypto->Init(nsICryptoHash::SHA256);
  NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "InitCrypto failed");

  return rv;
}

nsresult
LookupCacheV4::VerifyChecksum(const nsACString& aChecksum)
{
  nsCOMPtr<nsICryptoHash> crypto;
  nsresult rv = InitCrypto(crypto);
  if (NS_FAILED(rv)) {
    return rv;
  }

  PrefixStringMap map;
  mVLPrefixSet->GetPrefixes(map);

  VLPrefixSet loadPSet(map);
  uint32_t index = loadPSet.Count() + 1;
  for(;index > 0; index--) {
    nsDependentCSubstring prefix;
    if (!loadPSet.GetSmallestPrefix(prefix)) {
      break;
    }
    UpdateChecksum(crypto, prefix);
  }

  nsAutoCString checksum;
  crypto->Finish(false, checksum);

  if (checksum != aChecksum) {
    LOG(("Checksum mismatch when loading prefixes from file."));
    return NS_ERROR_FILE_CORRUPTED;
  }

  return NS_OK;
}

//////////////////////////////////////////////////////////////////////////
// A set of lightweight functions for reading/writing value from/to file.

namespace {

template<typename T>
struct ValueTraits
{
  static uint32_t Length(const T& aValue) { return sizeof(T); }
  static char* WritePtr(T& aValue, uint32_t aLength) { return (char*)&aValue; }
  static const char* ReadPtr(const T& aValue) { return (char*)&aValue; }
  static bool IsFixedLength() { return true; }
};

template<>
struct ValueTraits<nsACString>
{
  static bool IsFixedLength() { return false; }

  static uint32_t Length(const nsACString& aValue)
  {
    return aValue.Length();
  }

  static char* WritePtr(nsACString& aValue, uint32_t aLength)
  {
    aValue.SetLength(aLength);
    return aValue.BeginWriting();
  }

  static const char* ReadPtr(const nsACString& aValue)
  {
    return aValue.BeginReading();
  }
};

template<typename T> static nsresult
WriteValue(nsIOutputStream *aOutputStream, const T& aValue)
{
  uint32_t writeLength = ValueTraits<T>::Length(aValue);
  if (!ValueTraits<T>::IsFixedLength()) {
    // We need to write out the variable value length.
    nsresult rv = WriteValue(aOutputStream, writeLength);
    NS_ENSURE_SUCCESS(rv, rv);
  }

  // Write out the value.
  auto valueReadPtr = ValueTraits<T>::ReadPtr(aValue);
  uint32_t written;
  nsresult rv = aOutputStream->Write(valueReadPtr, writeLength, &written);
  if (NS_FAILED(rv) || written != writeLength) {
    LOG(("Failed to write the value."));
    return NS_FAILED(rv) ? rv : NS_ERROR_FAILURE;
  }

  return rv;
}

template<typename T> static nsresult
ReadValue(nsIInputStream* aInputStream, T& aValue)
{
  nsresult rv;

  uint32_t readLength;
  if (ValueTraits<T>::IsFixedLength()) {
    readLength = ValueTraits<T>::Length(aValue);
  } else {
    // Read the variable value length from file.
    nsresult rv = ReadValue(aInputStream, readLength);
    NS_ENSURE_SUCCESS(rv, rv);
  }

  // Read the value.
  uint32_t read;
  auto valueWritePtr = ValueTraits<T>::WritePtr(aValue, readLength);
  rv = aInputStream->Read(valueWritePtr, readLength, &read);
  if (NS_FAILED(rv) || read != readLength) {
    LOG(("Failed to read the value."));
    return NS_FAILED(rv) ? rv : NS_ERROR_FAILURE;
  }

  return rv;
}

} // end of unnamed namespace.
////////////////////////////////////////////////////////////////////////

nsresult
LookupCacheV4::WriteMetadata(TableUpdateV4* aTableUpdate)
{
  NS_ENSURE_ARG_POINTER(aTableUpdate);
  if (nsUrlClassifierDBService::ShutdownHasStarted()) {
    return NS_ERROR_ABORT;
  }

  nsCOMPtr<nsIFile> metaFile;
  nsresult rv = mStoreDirectory->Clone(getter_AddRefs(metaFile));
  NS_ENSURE_SUCCESS(rv, rv);

  rv = metaFile->AppendNative(mTableName + METADATA_SUFFIX);
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIOutputStream> outputStream;
  rv = NS_NewLocalFileOutputStream(getter_AddRefs(outputStream), metaFile,
                                   PR_WRONLY | PR_TRUNCATE | PR_CREATE_FILE);
  if (!NS_SUCCEEDED(rv)) {
    LOG(("Unable to create file to store metadata."));
    return rv;
  }

  // Write the state.
  rv = WriteValue(outputStream, aTableUpdate->ClientState());
  if (NS_FAILED(rv)) {
    LOG(("Failed to write the list state."));
    return rv;
  }

  // Write the checksum.
  rv = WriteValue(outputStream, aTableUpdate->Checksum());
  if (NS_FAILED(rv)) {
    LOG(("Failed to write the list checksum."));
    return rv;
  }

  return rv;
}

nsresult
LookupCacheV4::LoadMetadata(nsACString& aState, nsACString& aChecksum)
{
  nsCOMPtr<nsIFile> metaFile;
  nsresult rv = mStoreDirectory->Clone(getter_AddRefs(metaFile));
  NS_ENSURE_SUCCESS(rv, rv);

  rv = metaFile->AppendNative(mTableName + METADATA_SUFFIX);
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIInputStream> localInFile;
  rv = NS_NewLocalFileInputStream(getter_AddRefs(localInFile), metaFile,
                                  PR_RDONLY | nsIFile::OS_READAHEAD);
  if (NS_FAILED(rv)) {
    LOG(("Unable to open metadata file."));
    return rv;
  }

  // Read the list state.
  rv = ReadValue(localInFile, aState);
  if (NS_FAILED(rv)) {
    LOG(("Failed to read state."));
    return rv;
  }

  // Read the checksum.
  rv = ReadValue(localInFile, aChecksum);
  if (NS_FAILED(rv)) {
    LOG(("Failed to read checksum."));
    return rv;
  }

  return rv;
}

VLPrefixSet::VLPrefixSet(const PrefixStringMap& aMap)
  : mCount(0)
{
  for (auto iter = aMap.ConstIter(); !iter.Done(); iter.Next()) {
    uint32_t size = iter.Key();
    mMap.Put(size, new PrefixString(*iter.Data(), size));
    mCount += iter.Data()->Length() / size;
  }
}

VLPrefixSet::VLPrefixSet(const TableUpdateV4::PrefixStdStringMap& aMap)
  : mCount(0)
{
  for (auto iter = aMap.ConstIter(); !iter.Done(); iter.Next()) {
    uint32_t size = iter.Key();
    mMap.Put(size, new PrefixString(iter.Data()->GetPrefixString(), size));
    mCount += iter.Data()->GetPrefixString().Length() / size;
  }
}

void
VLPrefixSet::Merge(PrefixStringMap& aPrefixMap) {
  for (auto iter = mMap.ConstIter(); !iter.Done(); iter.Next()) {
    nsCString* prefixString = aPrefixMap.LookupOrAdd(iter.Key());
    PrefixString* str = iter.Data();

    if (str->get()) {
      prefixString->Append(str->get(), str->remaining());
    }
  }
}

bool
VLPrefixSet::GetSmallestPrefix(nsDependentCSubstring& aOutString) {
  PrefixString* pick = nullptr;
  for (auto iter = mMap.ConstIter(); !iter.Done(); iter.Next()) {
    PrefixString* str = iter.Data();

    if (!str->get()) {
      continue;
    }

    if (aOutString.IsEmpty()) {
      aOutString.Rebind(str->get(), iter.Key());
      pick = str;
      continue;
    }

    nsDependentCSubstring cur(str->get(), iter.Key());
    if (cur < aOutString) {
      aOutString.Rebind(str->get(), iter.Key());
      pick = str;
    }
  }

  if (pick) {
    pick->next();
  }

  return pick != nullptr;
}

} // namespace safebrowsing
} // namespace mozilla