src/extensions/browser/content_verify_job.cc

   1 // Copyright 2014 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 "extensions/browser/content_verify_job.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/metrics/histogram.h"
  10 #include "base/stl_util.h"
  11 #include "base/task_runner_util.h"
  12 #include "base/timer/elapsed_timer.h"
  13 #include "content/public/browser/browser_thread.h"
  14 #include "crypto/secure_hash.h"
  15 #include "crypto/sha2.h"
  16 #include "extensions/browser/content_hash_reader.h"
  17
  18 namespace extensions {
  19
  20 namespace {
  21
  22 ContentVerifyJob::TestDelegate* g_test_delegate = NULL;
  23
  24 class ScopedElapsedTimer {
  25  public:
  26   ScopedElapsedTimer(base::TimeDelta* total) : total_(total) { DCHECK(total_); }
  27
  28   ~ScopedElapsedTimer() { *total_ += timer.Elapsed(); }
  29
  30  private:
  31   // Some total amount of time we should add our elapsed time to at
  32   // destruction.
  33   base::TimeDelta* total_;
  34
  35   // A timer for how long this object has been alive.
  36   base::ElapsedTimer timer;
  37 };
  38
  39 }  // namespace
  40
  41 ContentVerifyJob::ContentVerifyJob(ContentHashReader* hash_reader,
  42                                    const FailureCallback& failure_callback)
  43     : done_reading_(false),
  44       hashes_ready_(false),
  45       total_bytes_read_(0),
  46       current_block_(0),
  47       current_hash_byte_count_(0),
  48       hash_reader_(hash_reader),
  49       failure_callback_(failure_callback),
  50       failed_(false) {
  51   // It's ok for this object to be constructed on a different thread from where
  52   // it's used.
  53   thread_checker_.DetachFromThread();
  54 }
  55
  56 ContentVerifyJob::~ContentVerifyJob() {
  57   UMA_HISTOGRAM_COUNTS("ExtensionContentVerifyJob.TimeSpentUS",
  58                        time_spent_.InMicroseconds());
  59 }
  60
  61 void ContentVerifyJob::Start() {
  62   DCHECK(thread_checker_.CalledOnValidThread());
  63   base::PostTaskAndReplyWithResult(
  64       content::BrowserThread::GetBlockingPool(),
  65       FROM_HERE,
  66       base::Bind(&ContentHashReader::Init, hash_reader_),
  67       base::Bind(&ContentVerifyJob::OnHashesReady, this));
  68 }
  69
  70 void ContentVerifyJob::BytesRead(int count, const char* data) {
  71   ScopedElapsedTimer timer(&time_spent_);
  72   DCHECK(thread_checker_.CalledOnValidThread());
  73   if (failed_)
  74     return;
  75   if (g_test_delegate) {
  76     FailureReason reason =
  77         g_test_delegate->BytesRead(hash_reader_->extension_id(), count, data);
  78     if (reason != NONE)
  79       return DispatchFailureCallback(reason);
  80   }
  81   if (!hashes_ready_) {
  82     queue_.append(data, count);
  83     return;
  84   }
  85   DCHECK_GE(count, 0);
  86   int bytes_added = 0;
  87
  88   while (bytes_added < count) {
  89     if (current_block_ >= hash_reader_->block_count())
  90       return DispatchFailureCallback(HASH_MISMATCH);
  91
  92     if (!current_hash_.get()) {
  93       current_hash_byte_count_ = 0;
  94       current_hash_.reset(
  95           crypto::SecureHash::Create(crypto::SecureHash::SHA256));
  96     }
  97     // Compute how many bytes we should hash, and add them to the current hash.
  98     int bytes_to_hash =
  99         std::min(hash_reader_->block_size() - current_hash_byte_count_,
 100                  count - bytes_added);
 101     DCHECK(bytes_to_hash > 0);
 102     current_hash_->Update(data + bytes_added, bytes_to_hash);
 103     bytes_added += bytes_to_hash;
 104     current_hash_byte_count_ += bytes_to_hash;
 105     total_bytes_read_ += bytes_to_hash;
 106
 107     // If we finished reading a block worth of data, finish computing the hash
 108     // for it and make sure the expected hash matches.
 109     if (current_hash_byte_count_ == hash_reader_->block_size() &&
 110         !FinishBlock()) {
 111       DispatchFailureCallback(HASH_MISMATCH);
 112       return;
 113     }
 114   }
 115 }
 116
 117 void ContentVerifyJob::DoneReading() {
 118   ScopedElapsedTimer timer(&time_spent_);
 119   DCHECK(thread_checker_.CalledOnValidThread());
 120   if (failed_)
 121     return;
 122   if (g_test_delegate) {
 123     FailureReason reason =
 124         g_test_delegate->DoneReading(hash_reader_->extension_id());
 125     if (reason != NONE) {
 126       DispatchFailureCallback(reason);
 127       return;
 128     }
 129   }
 130   done_reading_ = true;
 131   if (hashes_ready_ && !FinishBlock())
 132     DispatchFailureCallback(HASH_MISMATCH);
 133 }
 134
 135 bool ContentVerifyJob::FinishBlock() {
 136   if (current_hash_byte_count_ <= 0)
 137     return true;
 138   std::string final(crypto::kSHA256Length, 0);
 139   current_hash_->Finish(string_as_array(&final), final.size());
 140   current_hash_.reset();
 141   current_hash_byte_count_ = 0;
 142
 143   int block = current_block_++;
 144
 145   const std::string* expected_hash = NULL;
 146   if (!hash_reader_->GetHashForBlock(block, &expected_hash) ||
 147       *expected_hash != final)
 148     return false;
 149
 150   return true;
 151 }
 152
 153 void ContentVerifyJob::OnHashesReady(bool success) {
 154   if (!success && !g_test_delegate) {
 155     if (!hash_reader_->content_exists()) {
 156       // Ignore verification of non-existent resources.
 157       return;
 158     } else if (hash_reader_->have_verified_contents() &&
 159                hash_reader_->have_computed_hashes()) {
 160       DispatchFailureCallback(NO_HASHES_FOR_FILE);
 161     } else {
 162       DispatchFailureCallback(MISSING_ALL_HASHES);
 163     }
 164     return;
 165   }
 166
 167   hashes_ready_ = true;
 168   if (!queue_.empty()) {
 169     std::string tmp;
 170     queue_.swap(tmp);
 171     BytesRead(tmp.size(), string_as_array(&tmp));
 172   }
 173   if (done_reading_) {
 174     ScopedElapsedTimer timer(&time_spent_);
 175     if (!FinishBlock())
 176       DispatchFailureCallback(HASH_MISMATCH);
 177   }
 178 }
 179
 180 // static
 181 void ContentVerifyJob::SetDelegateForTests(TestDelegate* delegate) {
 182   g_test_delegate = delegate;
 183 }
 184
 185 void ContentVerifyJob::DispatchFailureCallback(FailureReason reason) {
 186   DCHECK(!failed_);
 187   failed_ = true;
 188   if (!failure_callback_.is_null()) {
 189     VLOG(1) << "job failed for " << hash_reader_->extension_id() << " "
 190             << hash_reader_->relative_path().MaybeAsASCII()
 191             << " reason:" << reason;
 192     failure_callback_.Run(reason);
 193     failure_callback_.Reset();
 194   }
 195 }
 196
 197 }  // namespace extensions