chrome/browser/safe_browsing/download_protection_service.cc

   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 "chrome/browser/safe_browsing/download_protection_service.h"
   6
   7 #include "base/bind.h"
   8 #include "base/compiler_specific.h"
   9 #include "base/format_macros.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/memory/weak_ptr.h"
  12 #include "base/metrics/field_trial.h"
  13 #include "base/metrics/histogram.h"
  14 #include "base/metrics/sparse_histogram.h"
  15 #include "base/sequenced_task_runner_helpers.h"
  16 #include "base/stl_util.h"
  17 #include "base/strings/string_number_conversions.h"
  18 #include "base/strings/string_util.h"
  19 #include "base/strings/stringprintf.h"
  20 #include "base/task/cancelable_task_tracker.h"
  21 #include "base/threading/sequenced_worker_pool.h"
  22 #include "base/time/time.h"
  23 #include "chrome/browser/browser_process.h"
  24 #include "chrome/browser/history/history_service.h"
  25 #include "chrome/browser/history/history_service_factory.h"
  26 #include "chrome/browser/profiles/profile.h"
  27 #include "chrome/browser/safe_browsing/binary_feature_extractor.h"
  28 #include "chrome/browser/safe_browsing/download_feedback_service.h"
  29 #include "chrome/browser/safe_browsing/safe_browsing_service.h"
  30 #include "chrome/browser/safe_browsing/sandboxed_zip_analyzer.h"
  31 #include "chrome/browser/ui/browser.h"
  32 #include "chrome/browser/ui/browser_list.h"
  33 #include "chrome/common/safe_browsing/csd.pb.h"
  34 #include "chrome/common/safe_browsing/download_protection_util.h"
  35 #include "chrome/common/safe_browsing/zip_analyzer.h"
  36 #include "chrome/common/url_constants.h"
  37 #include "components/google/core/browser/google_util.h"
  38 #include "content/public/browser/browser_thread.h"
  39 #include "content/public/browser/download_item.h"
  40 #include "content/public/browser/page_navigator.h"
  41 #include "crypto/sha2.h"
  42 #include "google_apis/google_api_keys.h"
  43 #include "net/base/escape.h"
  44 #include "net/base/load_flags.h"
  45 #include "net/cert/x509_cert_types.h"
  46 #include "net/cert/x509_certificate.h"
  47 #include "net/http/http_status_code.h"
  48 #include "net/url_request/url_fetcher.h"
  49 #include "net/url_request/url_fetcher_delegate.h"
  50 #include "net/url_request/url_request_context_getter.h"
  51 #include "net/url_request/url_request_status.h"
  52
  53 using content::BrowserThread;
  54
  55 namespace {
  56 static const int64 kDownloadRequestTimeoutMs = 7000;
  57 }  // namespace
  58
  59 namespace safe_browsing {
  60
  61 const char DownloadProtectionService::kDownloadRequestUrl[] =
  62     "https://sb-ssl.google.com/safebrowsing/clientreport/download";
  63
  64 namespace {
  65 // List of extensions for which we track some UMA stats.
  66 enum MaliciousExtensionType {
  67   EXTENSION_EXE,
  68   EXTENSION_MSI,
  69   EXTENSION_CAB,
  70   EXTENSION_SYS,
  71   EXTENSION_SCR,
  72   EXTENSION_DRV,
  73   EXTENSION_BAT,
  74   EXTENSION_ZIP,
  75   EXTENSION_RAR,
  76   EXTENSION_DLL,
  77   EXTENSION_PIF,
  78   EXTENSION_COM,
  79   EXTENSION_JAR,
  80   EXTENSION_CLASS,
  81   EXTENSION_PDF,
  82   EXTENSION_VB,
  83   EXTENSION_REG,
  84   EXTENSION_GRP,
  85   EXTENSION_OTHER,  // Groups all other extensions into one bucket.
  86   EXTENSION_CRX,
  87   EXTENSION_APK,
  88   EXTENSION_DMG,
  89   EXTENSION_PKG,
  90   EXTENSION_TORRENT,
  91   EXTENSION_MAX,
  92 };
  93
  94 MaliciousExtensionType GetExtensionType(const base::FilePath& f) {
  95   if (f.MatchesExtension(FILE_PATH_LITERAL(".exe"))) return EXTENSION_EXE;
  96   if (f.MatchesExtension(FILE_PATH_LITERAL(".msi"))) return EXTENSION_MSI;
  97   if (f.MatchesExtension(FILE_PATH_LITERAL(".cab"))) return EXTENSION_CAB;
  98   if (f.MatchesExtension(FILE_PATH_LITERAL(".sys"))) return EXTENSION_SYS;
  99   if (f.MatchesExtension(FILE_PATH_LITERAL(".scr"))) return EXTENSION_SCR;
 100   if (f.MatchesExtension(FILE_PATH_LITERAL(".drv"))) return EXTENSION_DRV;
 101   if (f.MatchesExtension(FILE_PATH_LITERAL(".bat"))) return EXTENSION_BAT;
 102   if (f.MatchesExtension(FILE_PATH_LITERAL(".zip"))) return EXTENSION_ZIP;
 103   if (f.MatchesExtension(FILE_PATH_LITERAL(".rar"))) return EXTENSION_RAR;
 104   if (f.MatchesExtension(FILE_PATH_LITERAL(".dll"))) return EXTENSION_DLL;
 105   if (f.MatchesExtension(FILE_PATH_LITERAL(".pif"))) return EXTENSION_PIF;
 106   if (f.MatchesExtension(FILE_PATH_LITERAL(".com"))) return EXTENSION_COM;
 107   if (f.MatchesExtension(FILE_PATH_LITERAL(".jar"))) return EXTENSION_JAR;
 108   if (f.MatchesExtension(FILE_PATH_LITERAL(".class"))) return EXTENSION_CLASS;
 109   if (f.MatchesExtension(FILE_PATH_LITERAL(".pdf"))) return EXTENSION_PDF;
 110   if (f.MatchesExtension(FILE_PATH_LITERAL(".vb"))) return EXTENSION_VB;
 111   if (f.MatchesExtension(FILE_PATH_LITERAL(".reg"))) return EXTENSION_REG;
 112   if (f.MatchesExtension(FILE_PATH_LITERAL(".grp"))) return EXTENSION_GRP;
 113   if (f.MatchesExtension(FILE_PATH_LITERAL(".crx"))) return EXTENSION_CRX;
 114   if (f.MatchesExtension(FILE_PATH_LITERAL(".apk"))) return EXTENSION_APK;
 115   if (f.MatchesExtension(FILE_PATH_LITERAL(".dmg"))) return EXTENSION_DMG;
 116   if (f.MatchesExtension(FILE_PATH_LITERAL(".pkg"))) return EXTENSION_PKG;
 117   if (f.MatchesExtension(FILE_PATH_LITERAL(".torrent")))
 118     return EXTENSION_TORRENT;
 119   return EXTENSION_OTHER;
 120 }
 121
 122 void RecordFileExtensionType(const base::FilePath& file) {
 123   UMA_HISTOGRAM_ENUMERATION("SBClientDownload.DownloadExtensions",
 124                             GetExtensionType(file),
 125                             EXTENSION_MAX);
 126 }
 127
 128 // Enumerate for histogramming purposes.
 129 // DO NOT CHANGE THE ORDERING OF THESE VALUES (different histogram data will
 130 // be mixed together based on their values).
 131 enum SBStatsType {
 132   DOWNLOAD_URL_CHECKS_TOTAL,
 133   DOWNLOAD_URL_CHECKS_CANCELED,
 134   DOWNLOAD_URL_CHECKS_MALWARE,
 135
 136   DOWNLOAD_HASH_CHECKS_TOTAL,
 137   DOWNLOAD_HASH_CHECKS_MALWARE,
 138
 139   // Memory space for histograms is determined by the max.
 140   // ALWAYS ADD NEW VALUES BEFORE THIS ONE.
 141   DOWNLOAD_CHECKS_MAX
 142 };
 143
 144 // Prepares URLs to be put into a ping message. Currently this just shortens
 145 // data: URIs, other URLs are included verbatim.
 146 std::string SanitizeUrl(const GURL& url) {
 147   std::string spec = url.spec();
 148   if (url.SchemeIs(url::kDataScheme)) {
 149     size_t comma_pos = spec.find(',');
 150     if (comma_pos != std::string::npos && comma_pos != spec.size() - 1) {
 151       std::string hash_value = crypto::SHA256HashString(spec);
 152       spec.erase(comma_pos + 1);
 153       spec += base::HexEncode(hash_value.data(), hash_value.size());
 154     }
 155   }
 156   return spec;
 157 }
 158
 159 }  // namespace
 160
 161 // Parent SafeBrowsing::Client class used to lookup the bad binary
 162 // URL and digest list.  There are two sub-classes (one for each list).
 163 class DownloadSBClient
 164     : public SafeBrowsingDatabaseManager::Client,
 165       public base::RefCountedThreadSafe<DownloadSBClient> {
 166  public:
 167   DownloadSBClient(
 168       const content::DownloadItem& item,
 169       const DownloadProtectionService::CheckDownloadCallback& callback,
 170       const scoped_refptr<SafeBrowsingUIManager>& ui_manager,
 171       SBStatsType total_type,
 172       SBStatsType dangerous_type)
 173       : sha256_hash_(item.GetHash()),
 174         url_chain_(item.GetUrlChain()),
 175         referrer_url_(item.GetReferrerUrl()),
 176         callback_(callback),
 177         ui_manager_(ui_manager),
 178         start_time_(base::TimeTicks::Now()),
 179         total_type_(total_type),
 180         dangerous_type_(dangerous_type) {}
 181
 182   virtual void StartCheck() = 0;
 183   virtual bool IsDangerous(SBThreatType threat_type) const = 0;
 184
 185  protected:
 186   friend class base::RefCountedThreadSafe<DownloadSBClient>;
 187   ~DownloadSBClient() override {}
 188
 189   void CheckDone(SBThreatType threat_type) {
 190     DownloadProtectionService::DownloadCheckResult result =
 191         IsDangerous(threat_type) ?
 192         DownloadProtectionService::DANGEROUS :
 193         DownloadProtectionService::SAFE;
 194     BrowserThread::PostTask(BrowserThread::UI,
 195                             FROM_HERE,
 196                             base::Bind(callback_, result));
 197     UpdateDownloadCheckStats(total_type_);
 198     if (threat_type != SB_THREAT_TYPE_SAFE) {
 199       UpdateDownloadCheckStats(dangerous_type_);
 200       BrowserThread::PostTask(
 201           BrowserThread::UI,
 202           FROM_HERE,
 203           base::Bind(&DownloadSBClient::ReportMalware,
 204                      this, threat_type));
 205     }
 206   }
 207
 208   void ReportMalware(SBThreatType threat_type) {
 209     std::string post_data;
 210     if (!sha256_hash_.empty())
 211       post_data += base::HexEncode(sha256_hash_.data(),
 212                                    sha256_hash_.size()) + "\n";
 213     for (size_t i = 0; i < url_chain_.size(); ++i) {
 214       post_data += url_chain_[i].spec() + "\n";
 215     }
 216     ui_manager_->ReportSafeBrowsingHit(
 217         url_chain_.back(),  // malicious_url
 218         url_chain_.front(), // page_url
 219         referrer_url_,
 220         true,  // is_subresource
 221         threat_type,
 222         post_data);
 223   }
 224
 225   void UpdateDownloadCheckStats(SBStatsType stat_type) {
 226     UMA_HISTOGRAM_ENUMERATION("SB2.DownloadChecks",
 227                               stat_type,
 228                               DOWNLOAD_CHECKS_MAX);
 229   }
 230
 231   std::string sha256_hash_;
 232   std::vector<GURL> url_chain_;
 233   GURL referrer_url_;
 234   DownloadProtectionService::CheckDownloadCallback callback_;
 235   scoped_refptr<SafeBrowsingUIManager> ui_manager_;
 236   base::TimeTicks start_time_;
 237
 238  private:
 239   const SBStatsType total_type_;
 240   const SBStatsType dangerous_type_;
 241
 242   DISALLOW_COPY_AND_ASSIGN(DownloadSBClient);
 243 };
 244
 245 class DownloadUrlSBClient : public DownloadSBClient {
 246  public:
 247   DownloadUrlSBClient(
 248       const content::DownloadItem& item,
 249       const DownloadProtectionService::CheckDownloadCallback& callback,
 250       const scoped_refptr<SafeBrowsingUIManager>& ui_manager,
 251       const scoped_refptr<SafeBrowsingDatabaseManager>& database_manager)
 252       : DownloadSBClient(item, callback, ui_manager,
 253                          DOWNLOAD_URL_CHECKS_TOTAL,
 254                          DOWNLOAD_URL_CHECKS_MALWARE),
 255         database_manager_(database_manager) { }
 256
 257   void StartCheck() override {
 258     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 259     if (!database_manager_.get() ||
 260         database_manager_->CheckDownloadUrl(url_chain_, this)) {
 261       CheckDone(SB_THREAT_TYPE_SAFE);
 262     } else {
 263       AddRef();  // SafeBrowsingService takes a pointer not a scoped_refptr.
 264     }
 265   }
 266
 267   bool IsDangerous(SBThreatType threat_type) const override {
 268     return threat_type == SB_THREAT_TYPE_BINARY_MALWARE_URL;
 269   }
 270
 271   void OnCheckDownloadUrlResult(const std::vector<GURL>& url_chain,
 272                                 SBThreatType threat_type) override {
 273     CheckDone(threat_type);
 274     UMA_HISTOGRAM_TIMES("SB2.DownloadUrlCheckDuration",
 275                         base::TimeTicks::Now() - start_time_);
 276     Release();
 277   }
 278
 279  protected:
 280   ~DownloadUrlSBClient() override {}
 281
 282  private:
 283   scoped_refptr<SafeBrowsingDatabaseManager> database_manager_;
 284
 285   DISALLOW_COPY_AND_ASSIGN(DownloadUrlSBClient);
 286 };
 287
 288 class DownloadProtectionService::CheckClientDownloadRequest
 289     : public base::RefCountedThreadSafe<
 290           DownloadProtectionService::CheckClientDownloadRequest,
 291           BrowserThread::DeleteOnUIThread>,
 292       public net::URLFetcherDelegate,
 293       public content::DownloadItem::Observer {
 294  public:
 295   CheckClientDownloadRequest(
 296       content::DownloadItem* item,
 297       const CheckDownloadCallback& callback,
 298       DownloadProtectionService* service,
 299       const scoped_refptr<SafeBrowsingDatabaseManager>& database_manager,
 300       BinaryFeatureExtractor* binary_feature_extractor)
 301       : item_(item),
 302         url_chain_(item->GetUrlChain()),
 303         referrer_url_(item->GetReferrerUrl()),
 304         tab_url_(item->GetTabUrl()),
 305         tab_referrer_url_(item->GetTabReferrerUrl()),
 306         zipped_executable_(false),
 307         callback_(callback),
 308         service_(service),
 309         binary_feature_extractor_(binary_feature_extractor),
 310         database_manager_(database_manager),
 311         pingback_enabled_(service_->enabled()),
 312         finished_(false),
 313         type_(ClientDownloadRequest::WIN_EXECUTABLE),
 314         start_time_(base::TimeTicks::Now()),
 315         weakptr_factory_(this) {
 316     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 317     item_->AddObserver(this);
 318   }
 319
 320   void Start() {
 321     DVLOG(2) << "Starting SafeBrowsing download check for: "
 322              << item_->DebugString(true);
 323     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 324     // TODO(noelutz): implement some cache to make sure we don't issue the same
 325     // request over and over again if a user downloads the same binary multiple
 326     // times.
 327     DownloadCheckResultReason reason = REASON_MAX;
 328     if (!IsSupportedDownload(
 329         *item_, item_->GetTargetFilePath(), &reason, &type_)) {
 330       switch (reason) {
 331         case REASON_EMPTY_URL_CHAIN:
 332         case REASON_INVALID_URL:
 333         case REASON_UNSUPPORTED_URL_SCHEME:
 334           PostFinishTask(UNKNOWN, reason);
 335           return;
 336
 337         case REASON_NOT_BINARY_FILE:
 338           RecordFileExtensionType(item_->GetTargetFilePath());
 339           PostFinishTask(UNKNOWN, reason);
 340           return;
 341
 342         default:
 343           // We only expect the reasons explicitly handled above.
 344           NOTREACHED();
 345       }
 346     }
 347     RecordFileExtensionType(item_->GetTargetFilePath());
 348
 349     // Compute features from the file contents. Note that we record histograms
 350     // based on the result, so this runs regardless of whether the pingbacks
 351     // are enabled.
 352     if (item_->GetTargetFilePath().MatchesExtension(
 353         FILE_PATH_LITERAL(".zip"))) {
 354       StartExtractZipFeatures();
 355     } else {
 356       DCHECK(!download_protection_util::IsArchiveFile(
 357           item_->GetTargetFilePath()));
 358       StartExtractFileFeatures();
 359     }
 360   }
 361
 362   // Start a timeout to cancel the request if it takes too long.
 363   // This should only be called after we have finished accessing the file.
 364   void StartTimeout() {
 365     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 366     if (!service_) {
 367       // Request has already been cancelled.
 368       return;
 369     }
 370     timeout_start_time_ = base::TimeTicks::Now();
 371     BrowserThread::PostDelayedTask(
 372         BrowserThread::UI,
 373         FROM_HERE,
 374         base::Bind(&CheckClientDownloadRequest::Cancel,
 375                    weakptr_factory_.GetWeakPtr()),
 376         base::TimeDelta::FromMilliseconds(
 377             service_->download_request_timeout_ms()));
 378   }
 379
 380   // Canceling a request will cause us to always report the result as UNKNOWN
 381   // unless a pending request is about to call FinishRequest.
 382   void Cancel() {
 383     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 384     if (fetcher_.get()) {
 385       // The DownloadProtectionService is going to release its reference, so we
 386       // might be destroyed before the URLFetcher completes.  Cancel the
 387       // fetcher so it does not try to invoke OnURLFetchComplete.
 388       fetcher_.reset();
 389     }
 390     // Note: If there is no fetcher, then some callback is still holding a
 391     // reference to this object.  We'll eventually wind up in some method on
 392     // the UI thread that will call FinishRequest() again.  If FinishRequest()
 393     // is called a second time, it will be a no-op.
 394     FinishRequest(UNKNOWN, REASON_REQUEST_CANCELED);
 395     // Calling FinishRequest might delete this object, we may be deleted by
 396     // this point.
 397   }
 398
 399   // content::DownloadItem::Observer implementation.
 400   void OnDownloadDestroyed(content::DownloadItem* download) override {
 401     Cancel();
 402     DCHECK(item_ == NULL);
 403   }
 404
 405   // From the net::URLFetcherDelegate interface.
 406   void OnURLFetchComplete(const net::URLFetcher* source) override {
 407     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 408     DCHECK_EQ(source, fetcher_.get());
 409     DVLOG(2) << "Received a response for URL: "
 410              << item_->GetUrlChain().back() << ": success="
 411              << source->GetStatus().is_success() << " response_code="
 412              << source->GetResponseCode();
 413     if (source->GetStatus().is_success()) {
 414       UMA_HISTOGRAM_SPARSE_SLOWLY(
 415           "SBClientDownload.DownloadRequestResponseCode",
 416           source->GetResponseCode());
 417     }
 418     UMA_HISTOGRAM_SPARSE_SLOWLY(
 419         "SBClientDownload.DownloadRequestNetError",
 420         -source->GetStatus().error());
 421     DownloadCheckResultReason reason = REASON_SERVER_PING_FAILED;
 422     DownloadCheckResult result = UNKNOWN;
 423     if (source->GetStatus().is_success() &&
 424         net::HTTP_OK == source->GetResponseCode()) {
 425       ClientDownloadResponse response;
 426       std::string data;
 427       bool got_data = source->GetResponseAsString(&data);
 428       DCHECK(got_data);
 429       if (!response.ParseFromString(data)) {
 430         reason = REASON_INVALID_RESPONSE_PROTO;
 431         result = UNKNOWN;
 432       } else if (response.verdict() == ClientDownloadResponse::SAFE) {
 433         reason = REASON_DOWNLOAD_SAFE;
 434         result = SAFE;
 435       } else if (service_ && !service_->IsSupportedDownload(
 436           *item_, item_->GetTargetFilePath())) {
 437         // The client of the download protection service assumes that we don't
 438         // support this download so we cannot return any other verdict than
 439         // UNKNOWN even if the server says it's dangerous to download this file.
 440         // Note: if service_ is NULL we already cancelled the request and
 441         // returned UNKNOWN.
 442         reason = REASON_DOWNLOAD_NOT_SUPPORTED;
 443         result = UNKNOWN;
 444       } else if (response.verdict() == ClientDownloadResponse::DANGEROUS) {
 445         reason = REASON_DOWNLOAD_DANGEROUS;
 446         result = DANGEROUS;
 447       } else if (response.verdict() == ClientDownloadResponse::UNCOMMON) {
 448         reason = REASON_DOWNLOAD_UNCOMMON;
 449         result = UNCOMMON;
 450       } else if (response.verdict() == ClientDownloadResponse::DANGEROUS_HOST) {
 451         reason = REASON_DOWNLOAD_DANGEROUS_HOST;
 452         result = DANGEROUS_HOST;
 453       } else if (
 454           response.verdict() == ClientDownloadResponse::POTENTIALLY_UNWANTED) {
 455         reason = REASON_DOWNLOAD_POTENTIALLY_UNWANTED;
 456         result = POTENTIALLY_UNWANTED;
 457       } else {
 458         LOG(DFATAL) << "Unknown download response verdict: "
 459                     << response.verdict();
 460         reason = REASON_INVALID_RESPONSE_VERDICT;
 461         result = UNKNOWN;
 462       }
 463       DownloadFeedbackService::MaybeStorePingsForDownload(
 464           result, item_, client_download_request_data_, data);
 465     }
 466     // We don't need the fetcher anymore.
 467     fetcher_.reset();
 468     UMA_HISTOGRAM_TIMES("SBClientDownload.DownloadRequestDuration",
 469                         base::TimeTicks::Now() - start_time_);
 470     UMA_HISTOGRAM_TIMES("SBClientDownload.DownloadRequestNetworkDuration",
 471                         base::TimeTicks::Now() - request_start_time_);
 472     FinishRequest(result, reason);
 473   }
 474
 475   static bool IsSupportedDownload(const content::DownloadItem& item,
 476                                   const base::FilePath& target_path,
 477                                   DownloadCheckResultReason* reason,
 478                                   ClientDownloadRequest::DownloadType* type) {
 479     if (item.GetUrlChain().empty()) {
 480       *reason = REASON_EMPTY_URL_CHAIN;
 481       return false;
 482     }
 483     const GURL& final_url = item.GetUrlChain().back();
 484     if (!final_url.is_valid() || final_url.is_empty()) {
 485       *reason = REASON_INVALID_URL;
 486       return false;
 487     }
 488     if (!download_protection_util::IsBinaryFile(target_path)) {
 489       *reason = REASON_NOT_BINARY_FILE;
 490       return false;
 491     }
 492     if ((!final_url.IsStandard() && !final_url.SchemeIsBlob() &&
 493          !final_url.SchemeIs(url::kDataScheme)) ||
 494         final_url.SchemeIsFile()) {
 495       *reason = REASON_UNSUPPORTED_URL_SCHEME;
 496       return false;
 497     }
 498     *type = download_protection_util::GetDownloadType(target_path);
 499     return true;
 500   }
 501
 502  private:
 503   friend struct BrowserThread::DeleteOnThread<BrowserThread::UI>;
 504   friend class base::DeleteHelper<CheckClientDownloadRequest>;
 505
 506   ~CheckClientDownloadRequest() override {
 507     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 508     DCHECK(item_ == NULL);
 509   }
 510
 511   void OnFileFeatureExtractionDone() {
 512     // This can run in any thread, since it just posts more messages.
 513
 514     // TODO(noelutz): DownloadInfo should also contain the IP address of
 515     // every URL in the redirect chain.  We also should check whether the
 516     // download URL is hosted on the internal network.
 517     BrowserThread::PostTask(
 518         BrowserThread::IO,
 519         FROM_HERE,
 520         base::Bind(&CheckClientDownloadRequest::CheckWhitelists, this));
 521
 522     // We wait until after the file checks finish to start the timeout, as
 523     // windows can cause permissions errors if the timeout fired while we were
 524     // checking the file signature and we tried to complete the download.
 525     BrowserThread::PostTask(
 526         BrowserThread::UI,
 527         FROM_HERE,
 528         base::Bind(&CheckClientDownloadRequest::StartTimeout, this));
 529   }
 530
 531   void StartExtractFileFeatures() {
 532     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 533     DCHECK(item_);  // Called directly from Start(), item should still exist.
 534     // Since we do blocking I/O, offload this to a worker thread.
 535     // The task does not need to block shutdown.
 536     BrowserThread::GetBlockingPool()->PostWorkerTaskWithShutdownBehavior(
 537         FROM_HERE,
 538         base::Bind(&CheckClientDownloadRequest::ExtractFileFeatures,
 539                    this, item_->GetFullPath()),
 540         base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
 541   }
 542
 543   void ExtractFileFeatures(const base::FilePath& file_path) {
 544     base::TimeTicks start_time = base::TimeTicks::Now();
 545     binary_feature_extractor_->CheckSignature(file_path, &signature_info_);
 546     bool is_signed = (signature_info_.certificate_chain_size() > 0);
 547     if (is_signed) {
 548       DVLOG(2) << "Downloaded a signed binary: " << file_path.value();
 549     } else {
 550       DVLOG(2) << "Downloaded an unsigned binary: "
 551                << file_path.value();
 552     }
 553     UMA_HISTOGRAM_BOOLEAN("SBClientDownload.SignedBinaryDownload", is_signed);
 554     UMA_HISTOGRAM_TIMES("SBClientDownload.ExtractSignatureFeaturesTime",
 555                         base::TimeTicks::Now() - start_time);
 556
 557     start_time = base::TimeTicks::Now();
 558     binary_feature_extractor_->ExtractImageHeaders(file_path, &image_headers_);
 559     UMA_HISTOGRAM_TIMES("SBClientDownload.ExtractImageHeadersTime",
 560                         base::TimeTicks::Now() - start_time);
 561
 562     OnFileFeatureExtractionDone();
 563   }
 564
 565   void StartExtractZipFeatures() {
 566     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 567     DCHECK(item_);  // Called directly from Start(), item should still exist.
 568     zip_analysis_start_time_ = base::TimeTicks::Now();
 569     // We give the zip analyzer a weak pointer to this object.  Since the
 570     // analyzer is refcounted, it might outlive the request.
 571     analyzer_ = new SandboxedZipAnalyzer(
 572         item_->GetFullPath(),
 573         base::Bind(&CheckClientDownloadRequest::OnZipAnalysisFinished,
 574                    weakptr_factory_.GetWeakPtr()));
 575     analyzer_->Start();
 576   }
 577
 578   void OnZipAnalysisFinished(const zip_analyzer::Results& results) {
 579     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 580     if (!service_)
 581       return;
 582     if (results.success) {
 583       zipped_executable_ = results.has_executable;
 584       DVLOG(1) << "Zip analysis finished for " << item_->GetFullPath().value()
 585                << ", has_executable=" << results.has_executable
 586                << " has_archive=" << results.has_archive;
 587     } else {
 588       DVLOG(1) << "Zip analysis failed for " << item_->GetFullPath().value();
 589     }
 590     UMA_HISTOGRAM_BOOLEAN("SBClientDownload.ZipFileHasExecutable",
 591                           zipped_executable_);
 592     UMA_HISTOGRAM_BOOLEAN("SBClientDownload.ZipFileHasArchiveButNoExecutable",
 593                           results.has_archive && !zipped_executable_);
 594     UMA_HISTOGRAM_TIMES("SBClientDownload.ExtractZipFeaturesTime",
 595                         base::TimeTicks::Now() - zip_analysis_start_time_);
 596
 597     if (!zipped_executable_) {
 598       PostFinishTask(UNKNOWN, REASON_ARCHIVE_WITHOUT_BINARIES);
 599       return;
 600     }
 601     OnFileFeatureExtractionDone();
 602   }
 603
 604   static void RecordCountOfSignedOrWhitelistedDownload() {
 605     UMA_HISTOGRAM_COUNTS("SBClientDownload.SignedOrWhitelistedDownload", 1);
 606   }
 607
 608   void CheckWhitelists() {
 609     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 610
 611     if (!database_manager_.get()) {
 612       PostFinishTask(UNKNOWN, REASON_SB_DISABLED);
 613       return;
 614     }
 615
 616     const GURL& url = url_chain_.back();
 617     if (url.is_valid() && database_manager_->MatchDownloadWhitelistUrl(url)) {
 618       DVLOG(2) << url << " is on the download whitelist.";
 619       RecordCountOfSignedOrWhitelistedDownload();
 620       // TODO(grt): Continue processing without uploading so that
 621       // ClientDownloadRequest callbacks can be run even for this type of safe
 622       // download.
 623       PostFinishTask(SAFE, REASON_WHITELISTED_URL);
 624       return;
 625     }
 626
 627     if (signature_info_.trusted()) {
 628       RecordCountOfSignedOrWhitelistedDownload();
 629       for (int i = 0; i < signature_info_.certificate_chain_size(); ++i) {
 630         if (CertificateChainIsWhitelisted(
 631                 signature_info_.certificate_chain(i))) {
 632           // TODO(grt): Continue processing without uploading so that
 633           // ClientDownloadRequest callbacks can be run even for this type of
 634           // safe download.
 635           PostFinishTask(SAFE, REASON_TRUSTED_EXECUTABLE);
 636           return;
 637         }
 638       }
 639     }
 640
 641     if (!pingback_enabled_) {
 642       PostFinishTask(UNKNOWN, REASON_PING_DISABLED);
 643       return;
 644     }
 645
 646     // Currently, the UI only works on Windows so we don't even bother with
 647     // pinging the server if we're not on Windows.
 648     // TODO(noelutz): change this code once the UI is done for Linux and Mac.
 649 #if defined(OS_MACOSX)
 650   // TODO(mattm): remove this (see crbug.com/414834).
 651   if (base::FieldTrialList::FindFullName("SafeBrowsingOSXClientDownloadPings")
 652       != "Enabled") {
 653     PostFinishTask(UNKNOWN, REASON_OS_NOT_SUPPORTED);
 654     return;
 655   }
 656 #endif
 657 #if defined(OS_WIN) || defined(OS_MACOSX)
 658     // The URLFetcher is owned by the UI thread, so post a message to
 659     // start the pingback.
 660     BrowserThread::PostTask(
 661         BrowserThread::UI,
 662         FROM_HERE,
 663         base::Bind(&CheckClientDownloadRequest::GetTabRedirects, this));
 664 #else
 665     PostFinishTask(UNKNOWN, REASON_OS_NOT_SUPPORTED);
 666 #endif
 667   }
 668
 669   void GetTabRedirects() {
 670     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 671     if (!service_)
 672       return;
 673
 674     if (!tab_url_.is_valid()) {
 675       SendRequest();
 676       return;
 677     }
 678
 679     Profile* profile = Profile::FromBrowserContext(item_->GetBrowserContext());
 680     HistoryService* history = HistoryServiceFactory::GetForProfile(
 681         profile, ServiceAccessType::EXPLICIT_ACCESS);
 682     if (!history) {
 683       SendRequest();
 684       return;
 685     }
 686
 687     history->QueryRedirectsTo(
 688         tab_url_,
 689         base::Bind(&CheckClientDownloadRequest::OnGotTabRedirects,
 690                    base::Unretained(this),
 691                    tab_url_),
 692         &request_tracker_);
 693   }
 694
 695   void OnGotTabRedirects(const GURL& url,
 696                          const history::RedirectList* redirect_list) {
 697     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 698     DCHECK_EQ(url, tab_url_);
 699     if (!service_)
 700       return;
 701
 702     if (!redirect_list->empty()) {
 703       tab_redirects_.insert(
 704           tab_redirects_.end(), redirect_list->rbegin(), redirect_list->rend());
 705     }
 706
 707     SendRequest();
 708   }
 709
 710   void SendRequest() {
 711     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 712
 713     // This is our last chance to check whether the request has been canceled
 714     // before sending it.
 715     if (!service_)
 716       return;
 717
 718     ClientDownloadRequest request;
 719     request.set_url(SanitizeUrl(item_->GetUrlChain().back()));
 720     request.mutable_digests()->set_sha256(item_->GetHash());
 721     request.set_length(item_->GetReceivedBytes());
 722     for (size_t i = 0; i < item_->GetUrlChain().size(); ++i) {
 723       ClientDownloadRequest::Resource* resource = request.add_resources();
 724       resource->set_url(SanitizeUrl(item_->GetUrlChain()[i]));
 725       if (i == item_->GetUrlChain().size() - 1) {
 726         // The last URL in the chain is the download URL.
 727         resource->set_type(ClientDownloadRequest::DOWNLOAD_URL);
 728         resource->set_referrer(SanitizeUrl(item_->GetReferrerUrl()));
 729         DVLOG(2) << "dl url " << resource->url();
 730         if (!item_->GetRemoteAddress().empty()) {
 731           resource->set_remote_ip(item_->GetRemoteAddress());
 732           DVLOG(2) << "  dl url remote addr: " << resource->remote_ip();
 733         }
 734         DVLOG(2) << "dl referrer " << resource->referrer();
 735       } else {
 736         DVLOG(2) << "dl redirect " << i << " " << resource->url();
 737         resource->set_type(ClientDownloadRequest::DOWNLOAD_REDIRECT);
 738       }
 739       // TODO(noelutz): fill out the remote IP addresses.
 740     }
 741     // TODO(mattm): fill out the remote IP addresses for tab resources.
 742     for (size_t i = 0; i < tab_redirects_.size(); ++i) {
 743       ClientDownloadRequest::Resource* resource = request.add_resources();
 744       DVLOG(2) << "tab redirect " << i << " " << tab_redirects_[i].spec();
 745       resource->set_url(SanitizeUrl(tab_redirects_[i]));
 746       resource->set_type(ClientDownloadRequest::TAB_REDIRECT);
 747     }
 748     if (tab_url_.is_valid()) {
 749       ClientDownloadRequest::Resource* resource = request.add_resources();
 750       resource->set_url(SanitizeUrl(tab_url_));
 751       DVLOG(2) << "tab url " << resource->url();
 752       resource->set_type(ClientDownloadRequest::TAB_URL);
 753       if (tab_referrer_url_.is_valid()) {
 754         resource->set_referrer(SanitizeUrl(tab_referrer_url_));
 755         DVLOG(2) << "tab referrer " << resource->referrer();
 756       }
 757     }
 758
 759     request.set_user_initiated(item_->HasUserGesture());
 760     request.set_file_basename(
 761         item_->GetTargetFilePath().BaseName().AsUTF8Unsafe());
 762     request.set_download_type(type_);
 763     request.mutable_signature()->CopyFrom(signature_info_);
 764     request.mutable_image_headers()->CopyFrom(image_headers_);
 765     if (!request.SerializeToString(&client_download_request_data_)) {
 766       FinishRequest(UNKNOWN, REASON_INVALID_REQUEST_PROTO);
 767       return;
 768     }
 769
 770     service_->client_download_request_callbacks_.Notify(item_, &request);
 771
 772     DVLOG(2) << "Sending a request for URL: "
 773              << item_->GetUrlChain().back();
 774     fetcher_.reset(net::URLFetcher::Create(0 /* ID used for testing */,
 775                                            GetDownloadRequestUrl(),
 776                                            net::URLFetcher::POST,
 777                                            this));
 778     fetcher_->SetLoadFlags(net::LOAD_DISABLE_CACHE);
 779     fetcher_->SetAutomaticallyRetryOn5xx(false);  // Don't retry on error.
 780     fetcher_->SetRequestContext(service_->request_context_getter_.get());
 781     fetcher_->SetUploadData("application/octet-stream",
 782                             client_download_request_data_);
 783     request_start_time_ = base::TimeTicks::Now();
 784     UMA_HISTOGRAM_COUNTS("SBClientDownload.DownloadRequestPayloadSize",
 785                          client_download_request_data_.size());
 786     fetcher_->Start();
 787   }
 788
 789   void PostFinishTask(DownloadCheckResult result,
 790                       DownloadCheckResultReason reason) {
 791     BrowserThread::PostTask(
 792         BrowserThread::UI,
 793         FROM_HERE,
 794         base::Bind(&CheckClientDownloadRequest::FinishRequest, this, result,
 795                    reason));
 796   }
 797
 798   void FinishRequest(DownloadCheckResult result,
 799                      DownloadCheckResultReason reason) {
 800     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 801     if (finished_) {
 802       return;
 803     }
 804     finished_ = true;
 805     // Ensure the timeout task is cancelled while we still have a non-zero
 806     // refcount. (crbug.com/240449)
 807     weakptr_factory_.InvalidateWeakPtrs();
 808     if (!request_start_time_.is_null()) {
 809       UMA_HISTOGRAM_ENUMERATION("SBClientDownload.DownloadRequestNetworkStats",
 810                                 reason,
 811                                 REASON_MAX);
 812     }
 813     if (!timeout_start_time_.is_null()) {
 814       UMA_HISTOGRAM_ENUMERATION("SBClientDownload.DownloadRequestTimeoutStats",
 815                                 reason,
 816                                 REASON_MAX);
 817       if (reason != REASON_REQUEST_CANCELED) {
 818         UMA_HISTOGRAM_TIMES("SBClientDownload.DownloadRequestTimeoutDuration",
 819                             base::TimeTicks::Now() - timeout_start_time_);
 820       }
 821     }
 822     if (result == SAFE && (reason == REASON_WHITELISTED_URL ||
 823                            reason == REASON_TRUSTED_EXECUTABLE)) {
 824       // Due to the short-circuit logic in CheckWhitelists (see TODOs there), a
 825       // ClientDownloadRequest was not generated for this download and callbacks
 826       // were not run. Run them now with null to indicate that a download has
 827       // taken place.
 828       // TODO(grt): persist metadata for these downloads as well.
 829       service_->client_download_request_callbacks_.Notify(item_, nullptr);
 830     }
 831     if (service_) {
 832       DVLOG(2) << "SafeBrowsing download verdict for: "
 833                << item_->DebugString(true) << " verdict:" << reason
 834                << " result:" << result;
 835       UMA_HISTOGRAM_ENUMERATION("SBClientDownload.CheckDownloadStats",
 836                                 reason,
 837                                 REASON_MAX);
 838 #if defined(OS_MACOSX)
 839       // OSX is currently sending pings only for evaluation purposes, ignore
 840       // the result for now.
 841       // TODO(mattm): remove this and update the ifdef in
 842       // DownloadItemImpl::IsDangerous (see crbug.com/413968).
 843       result = UNKNOWN;
 844 #endif
 845       callback_.Run(result);
 846       item_->RemoveObserver(this);
 847       item_ = NULL;
 848       DownloadProtectionService* service = service_;
 849       service_ = NULL;
 850       service->RequestFinished(this);
 851       // DownloadProtectionService::RequestFinished will decrement our refcount,
 852       // so we may be deleted now.
 853     } else {
 854       callback_.Run(UNKNOWN);
 855     }
 856   }
 857
 858   bool CertificateChainIsWhitelisted(
 859       const ClientDownloadRequest_CertificateChain& chain) {
 860     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 861     if (chain.element_size() < 2) {
 862       // We need to have both a signing certificate and its issuer certificate
 863       // present to construct a whitelist entry.
 864       return false;
 865     }
 866     scoped_refptr<net::X509Certificate> cert =
 867         net::X509Certificate::CreateFromBytes(
 868             chain.element(0).certificate().data(),
 869             chain.element(0).certificate().size());
 870     if (!cert.get()) {
 871       return false;
 872     }
 873
 874     for (int i = 1; i < chain.element_size(); ++i) {
 875       scoped_refptr<net::X509Certificate> issuer =
 876           net::X509Certificate::CreateFromBytes(
 877               chain.element(i).certificate().data(),
 878               chain.element(i).certificate().size());
 879       if (!issuer.get()) {
 880         return false;
 881       }
 882       std::vector<std::string> whitelist_strings;
 883       DownloadProtectionService::GetCertificateWhitelistStrings(
 884           *cert.get(), *issuer.get(), &whitelist_strings);
 885       for (size_t j = 0; j < whitelist_strings.size(); ++j) {
 886         if (database_manager_->MatchDownloadWhitelistString(
 887                 whitelist_strings[j])) {
 888           DVLOG(2) << "Certificate matched whitelist, cert="
 889                    << cert->subject().GetDisplayName()
 890                    << " issuer=" << issuer->subject().GetDisplayName();
 891           return true;
 892         }
 893       }
 894       cert = issuer;
 895     }
 896     return false;
 897   }
 898
 899   // The DownloadItem we are checking. Will be NULL if the request has been
 900   // canceled. Must be accessed only on UI thread.
 901   content::DownloadItem* item_;
 902   // Copies of data from |item_| for access on other threads.
 903   std::vector<GURL> url_chain_;
 904   GURL referrer_url_;
 905   // URL chain of redirects leading to (but not including) |tab_url|.
 906   std::vector<GURL> tab_redirects_;
 907   // URL and referrer of the window the download was started from.
 908   GURL tab_url_;
 909   GURL tab_referrer_url_;
 910
 911   bool zipped_executable_;
 912   ClientDownloadRequest_SignatureInfo signature_info_;
 913   ClientDownloadRequest_ImageHeaders image_headers_;
 914   CheckDownloadCallback callback_;
 915   // Will be NULL if the request has been canceled.
 916   DownloadProtectionService* service_;
 917   scoped_refptr<BinaryFeatureExtractor> binary_feature_extractor_;
 918   scoped_refptr<SafeBrowsingDatabaseManager> database_manager_;
 919   const bool pingback_enabled_;
 920   scoped_ptr<net::URLFetcher> fetcher_;
 921   scoped_refptr<SandboxedZipAnalyzer> analyzer_;
 922   base::TimeTicks zip_analysis_start_time_;
 923   bool finished_;
 924   ClientDownloadRequest::DownloadType type_;
 925   std::string client_download_request_data_;
 926   base::CancelableTaskTracker request_tracker_;  // For HistoryService lookup.
 927   base::TimeTicks start_time_;  // Used for stats.
 928   base::TimeTicks timeout_start_time_;
 929   base::TimeTicks request_start_time_;
 930   base::WeakPtrFactory<CheckClientDownloadRequest> weakptr_factory_;
 931
 932   DISALLOW_COPY_AND_ASSIGN(CheckClientDownloadRequest);
 933 };
 934
 935 DownloadProtectionService::DownloadProtectionService(
 936     SafeBrowsingService* sb_service,
 937     net::URLRequestContextGetter* request_context_getter)
 938     : request_context_getter_(request_context_getter),
 939       enabled_(false),
 940       binary_feature_extractor_(new BinaryFeatureExtractor()),
 941       download_request_timeout_ms_(kDownloadRequestTimeoutMs),
 942       feedback_service_(new DownloadFeedbackService(
 943           request_context_getter, BrowserThread::GetBlockingPool())) {
 944
 945   if (sb_service) {
 946     ui_manager_ = sb_service->ui_manager();
 947     database_manager_ = sb_service->database_manager();
 948   }
 949 }
 950
 951 DownloadProtectionService::~DownloadProtectionService() {
 952   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 953   CancelPendingRequests();
 954 }
 955
 956 void DownloadProtectionService::SetEnabled(bool enabled) {
 957   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 958   if (enabled == enabled_) {
 959     return;
 960   }
 961   enabled_ = enabled;
 962   if (!enabled_) {
 963     CancelPendingRequests();
 964   }
 965 }
 966
 967 void DownloadProtectionService::CheckClientDownload(
 968     content::DownloadItem* item,
 969     const CheckDownloadCallback& callback) {
 970   scoped_refptr<CheckClientDownloadRequest> request(
 971       new CheckClientDownloadRequest(item, callback, this,
 972                                      database_manager_,
 973                                      binary_feature_extractor_.get()));
 974   download_requests_.insert(request);
 975   request->Start();
 976 }
 977
 978 void DownloadProtectionService::CheckDownloadUrl(
 979     const content::DownloadItem& item,
 980     const CheckDownloadCallback& callback) {
 981   DCHECK(!item.GetUrlChain().empty());
 982   scoped_refptr<DownloadUrlSBClient> client(
 983       new DownloadUrlSBClient(item, callback, ui_manager_, database_manager_));
 984   // The client will release itself once it is done.
 985   BrowserThread::PostTask(
 986         BrowserThread::IO,
 987         FROM_HERE,
 988         base::Bind(&DownloadUrlSBClient::StartCheck, client));
 989 }
 990
 991 bool DownloadProtectionService::IsSupportedDownload(
 992     const content::DownloadItem& item,
 993     const base::FilePath& target_path) const {
 994   // Currently, the UI is only enabled on Windows.  On Mac we send the ping but
 995   // ignore the result (see ifdef in FinishRequest).  On Linux we still
 996   // want to show the dangerous file type warning if the file is possibly
 997   // dangerous which means we have to always return false here.
 998 #if defined(OS_WIN)
 999   DownloadCheckResultReason reason = REASON_MAX;
1000   ClientDownloadRequest::DownloadType type =
1001       ClientDownloadRequest::WIN_EXECUTABLE;
1002   return (CheckClientDownloadRequest::IsSupportedDownload(
1003               item, target_path, &reason, &type) &&
1004           (ClientDownloadRequest::CHROME_EXTENSION != type));
1005 #else
1006   return false;
1007 #endif
1008 }
1009
1010 DownloadProtectionService::ClientDownloadRequestSubscription
1011 DownloadProtectionService::RegisterClientDownloadRequestCallback(
1012     const ClientDownloadRequestCallback& callback) {
1013   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
1014   return client_download_request_callbacks_.Add(callback);
1015 }
1016
1017 void DownloadProtectionService::CancelPendingRequests() {
1018   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
1019   for (std::set<scoped_refptr<CheckClientDownloadRequest> >::iterator it =
1020            download_requests_.begin();
1021        it != download_requests_.end();) {
1022     // We need to advance the iterator before we cancel because canceling
1023     // the request will invalidate it when RequestFinished is called below.
1024     scoped_refptr<CheckClientDownloadRequest> tmp = *it++;
1025     tmp->Cancel();
1026   }
1027   DCHECK(download_requests_.empty());
1028 }
1029
1030 void DownloadProtectionService::RequestFinished(
1031     CheckClientDownloadRequest* request) {
1032   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
1033   std::set<scoped_refptr<CheckClientDownloadRequest> >::iterator it =
1034       download_requests_.find(request);
1035   DCHECK(it != download_requests_.end());
1036   download_requests_.erase(*it);
1037 }
1038
1039 void DownloadProtectionService::ShowDetailsForDownload(
1040     const content::DownloadItem& item,
1041     content::PageNavigator* navigator) {
1042   GURL learn_more_url(chrome::kDownloadScanningLearnMoreURL);
1043   learn_more_url = google_util::AppendGoogleLocaleParam(
1044       learn_more_url, g_browser_process->GetApplicationLocale());
1045   navigator->OpenURL(
1046       content::OpenURLParams(learn_more_url,
1047                              content::Referrer(),
1048                              NEW_FOREGROUND_TAB,
1049                              ui::PAGE_TRANSITION_LINK,
1050                              false));
1051 }
1052
1053 namespace {
1054 // Escapes a certificate attribute so that it can be used in a whitelist
1055 // entry.  Currently, we only escape slashes, since they are used as a
1056 // separator between attributes.
1057 std::string EscapeCertAttribute(const std::string& attribute) {
1058   std::string escaped;
1059   for (size_t i = 0; i < attribute.size(); ++i) {
1060     if (attribute[i] == '%') {
1061       escaped.append("%25");
1062     } else if (attribute[i] == '/') {
1063       escaped.append("%2F");
1064     } else {
1065       escaped.push_back(attribute[i]);
1066     }
1067   }
1068   return escaped;
1069 }
1070 }  // namespace
1071
1072 // static
1073 void DownloadProtectionService::GetCertificateWhitelistStrings(
1074     const net::X509Certificate& certificate,
1075     const net::X509Certificate& issuer,
1076     std::vector<std::string>* whitelist_strings) {
1077   // The whitelist paths are in the format:
1078   // cert/<ascii issuer fingerprint>[/CN=common_name][/O=org][/OU=unit]
1079   //
1080   // Any of CN, O, or OU may be omitted from the whitelist entry, in which
1081   // case they match anything.  However, the attributes that do appear will
1082   // always be in the order shown above.  At least one attribute will always
1083   // be present.
1084
1085   const net::CertPrincipal& subject = certificate.subject();
1086   std::vector<std::string> ou_tokens;
1087   for (size_t i = 0; i < subject.organization_unit_names.size(); ++i) {
1088     ou_tokens.push_back(
1089         "/OU=" + EscapeCertAttribute(subject.organization_unit_names[i]));
1090   }
1091
1092   std::vector<std::string> o_tokens;
1093   for (size_t i = 0; i < subject.organization_names.size(); ++i) {
1094     o_tokens.push_back(
1095         "/O=" + EscapeCertAttribute(subject.organization_names[i]));
1096   }
1097
1098   std::string cn_token;
1099   if (!subject.common_name.empty()) {
1100     cn_token = "/CN=" + EscapeCertAttribute(subject.common_name);
1101   }
1102
1103   std::set<std::string> paths_to_check;
1104   if (!cn_token.empty()) {
1105     paths_to_check.insert(cn_token);
1106   }
1107   for (size_t i = 0; i < o_tokens.size(); ++i) {
1108     paths_to_check.insert(cn_token + o_tokens[i]);
1109     paths_to_check.insert(o_tokens[i]);
1110     for (size_t j = 0; j < ou_tokens.size(); ++j) {
1111       paths_to_check.insert(cn_token + o_tokens[i] + ou_tokens[j]);
1112       paths_to_check.insert(o_tokens[i] + ou_tokens[j]);
1113     }
1114   }
1115   for (size_t i = 0; i < ou_tokens.size(); ++i) {
1116     paths_to_check.insert(cn_token + ou_tokens[i]);
1117     paths_to_check.insert(ou_tokens[i]);
1118   }
1119
1120   std::string issuer_fp = base::HexEncode(issuer.fingerprint().data,
1121                                           sizeof(issuer.fingerprint().data));
1122   for (std::set<std::string>::iterator it = paths_to_check.begin();
1123        it != paths_to_check.end(); ++it) {
1124     whitelist_strings->push_back("cert/" + issuer_fp + *it);
1125   }
1126 }
1127
1128 // static
1129 GURL DownloadProtectionService::GetDownloadRequestUrl() {
1130   GURL url(kDownloadRequestUrl);
1131   std::string api_key = google_apis::GetAPIKey();
1132   if (!api_key.empty())
1133     url = url.Resolve("?key=" + net::EscapeQueryParamValue(api_key, true));
1134
1135   return url;
1136 }
1137
1138 }  // namespace safe_browsing