src/content/browser/loader/buffered_resource_handler.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 "content/browser/loader/buffered_resource_handler.h"
   6
   7 #include <vector>
   8
   9 #include "base/bind.h"
  10 #include "base/logging.h"
  11 #include "base/metrics/histogram.h"
  12 #include "base/strings/string_util.h"
  13 #include "content/browser/download/download_resource_handler.h"
  14 #include "content/browser/download/download_stats.h"
  15 #include "content/browser/loader/certificate_resource_handler.h"
  16 #include "content/browser/loader/resource_dispatcher_host_impl.h"
  17 #include "content/browser/loader/resource_request_info_impl.h"
  18 #include "content/browser/plugin_service_impl.h"
  19 #include "content/public/browser/content_browser_client.h"
  20 #include "content/public/browser/download_item.h"
  21 #include "content/public/browser/download_save_info.h"
  22 #include "content/public/browser/download_url_parameters.h"
  23 #include "content/public/browser/resource_context.h"
  24 #include "content/public/browser/resource_dispatcher_host_delegate.h"
  25 #include "content/public/common/resource_response.h"
  26 #include "content/public/common/webplugininfo.h"
  27 #include "net/base/io_buffer.h"
  28 #include "net/base/mime_sniffer.h"
  29 #include "net/base/mime_util.h"
  30 #include "net/base/net_errors.h"
  31 #include "net/http/http_content_disposition.h"
  32 #include "net/http/http_response_headers.h"
  33
  34 namespace content {
  35
  36 namespace {
  37
  38 void RecordSnifferMetrics(bool sniffing_blocked,
  39                           bool we_would_like_to_sniff,
  40                           const std::string& mime_type) {
  41   static base::HistogramBase* nosniff_usage(NULL);
  42   if (!nosniff_usage)
  43     nosniff_usage = base::BooleanHistogram::FactoryGet(
  44         "nosniff.usage", base::HistogramBase::kUmaTargetedHistogramFlag);
  45   nosniff_usage->AddBoolean(sniffing_blocked);
  46
  47   if (sniffing_blocked) {
  48     static base::HistogramBase* nosniff_otherwise(NULL);
  49     if (!nosniff_otherwise)
  50       nosniff_otherwise = base::BooleanHistogram::FactoryGet(
  51           "nosniff.otherwise", base::HistogramBase::kUmaTargetedHistogramFlag);
  52     nosniff_otherwise->AddBoolean(we_would_like_to_sniff);
  53
  54     static base::HistogramBase* nosniff_empty_mime_type(NULL);
  55     if (!nosniff_empty_mime_type)
  56       nosniff_empty_mime_type = base::BooleanHistogram::FactoryGet(
  57           "nosniff.empty_mime_type",
  58           base::HistogramBase::kUmaTargetedHistogramFlag);
  59     nosniff_empty_mime_type->AddBoolean(mime_type.empty());
  60   }
  61 }
  62
  63 // Used to write into an existing IOBuffer at a given offset.
  64 class DependentIOBuffer : public net::WrappedIOBuffer {
  65  public:
  66   DependentIOBuffer(net::IOBuffer* buf, int offset)
  67       : net::WrappedIOBuffer(buf->data() + offset),
  68         buf_(buf) {
  69   }
  70
  71  private:
  72   virtual ~DependentIOBuffer() {}
  73
  74   scoped_refptr<net::IOBuffer> buf_;
  75 };
  76
  77 }  // namespace
  78
  79 BufferedResourceHandler::BufferedResourceHandler(
  80     scoped_ptr<ResourceHandler> next_handler,
  81     ResourceDispatcherHostImpl* host,
  82     net::URLRequest* request)
  83     : LayeredResourceHandler(request, next_handler.Pass()),
  84       state_(STATE_STARTING),
  85       host_(host),
  86       read_buffer_size_(0),
  87       bytes_read_(0),
  88       must_download_(false),
  89       must_download_is_set_(false),
  90       weak_ptr_factory_(this) {
  91 }
  92
  93 BufferedResourceHandler::~BufferedResourceHandler() {
  94 }
  95
  96 void BufferedResourceHandler::SetController(ResourceController* controller) {
  97   ResourceHandler::SetController(controller);
  98
  99   // Downstream handlers see us as their ResourceController, which allows us to
 100   // consume part or all of the resource response, and then later replay it to
 101   // downstream handler.
 102   DCHECK(next_handler_.get());
 103   next_handler_->SetController(this);
 104 }
 105
 106 bool BufferedResourceHandler::OnResponseStarted(
 107     int request_id,
 108     ResourceResponse* response,
 109     bool* defer) {
 110   response_ = response;
 111
 112   // TODO(darin): It is very odd to special-case 304 responses at this level.
 113   // We do so only because the code always has, see r24977 and r29355.  The
 114   // fact that 204 is no longer special-cased this way suggests that 304 need
 115   // not be special-cased either.
 116   //
 117   // The network stack only forwards 304 responses that were not received in
 118   // response to a conditional request (i.e., If-Modified-Since).  Other 304
 119   // responses end up being translated to 200 or whatever the cached response
 120   // code happens to be.  It should be very rare to see a 304 at this level.
 121
 122   if (!(response_->head.headers.get() &&
 123         response_->head.headers->response_code() == 304)) {
 124     if (ShouldSniffContent()) {
 125       state_ = STATE_BUFFERING;
 126       return true;
 127     }
 128
 129     if (response_->head.mime_type.empty()) {
 130       // Ugg.  The server told us not to sniff the content but didn't give us
 131       // a mime type.  What's a browser to do?  Turns out, we're supposed to
 132       // treat the response as "text/plain".  This is the most secure option.
 133       response_->head.mime_type.assign("text/plain");
 134     }
 135
 136     // Treat feed types as text/plain.
 137     if (response_->head.mime_type == "application/rss+xml" ||
 138         response_->head.mime_type == "application/atom+xml") {
 139       response_->head.mime_type.assign("text/plain");
 140     }
 141   }
 142
 143   state_ = STATE_PROCESSING;
 144   return ProcessResponse(defer);
 145 }
 146
 147 // We'll let the original event handler provide a buffer, and reuse it for
 148 // subsequent reads until we're done buffering.
 149 bool BufferedResourceHandler::OnWillRead(int request_id,
 150                                          scoped_refptr<net::IOBuffer>* buf,
 151                                          int* buf_size,
 152                                          int min_size) {
 153   if (state_ == STATE_STREAMING)
 154     return next_handler_->OnWillRead(request_id, buf, buf_size, min_size);
 155
 156   DCHECK_EQ(-1, min_size);
 157
 158   if (read_buffer_.get()) {
 159     CHECK_LT(bytes_read_, read_buffer_size_);
 160     *buf = new DependentIOBuffer(read_buffer_.get(), bytes_read_);
 161     *buf_size = read_buffer_size_ - bytes_read_;
 162   } else {
 163     if (!next_handler_->OnWillRead(request_id, buf, buf_size, min_size))
 164       return false;
 165
 166     read_buffer_ = *buf;
 167     read_buffer_size_ = *buf_size;
 168     DCHECK_GE(read_buffer_size_, net::kMaxBytesToSniff * 2);
 169   }
 170   return true;
 171 }
 172
 173 bool BufferedResourceHandler::OnReadCompleted(int request_id, int bytes_read,
 174                                               bool* defer) {
 175   if (state_ == STATE_STREAMING)
 176     return next_handler_->OnReadCompleted(request_id, bytes_read, defer);
 177
 178   DCHECK_EQ(state_, STATE_BUFFERING);
 179   bytes_read_ += bytes_read;
 180
 181   if (!DetermineMimeType() && (bytes_read > 0))
 182     return true;  // Needs more data, so keep buffering.
 183
 184   state_ = STATE_PROCESSING;
 185   return ProcessResponse(defer);
 186 }
 187
 188 bool BufferedResourceHandler::OnResponseCompleted(
 189     int request_id,
 190     const net::URLRequestStatus& status,
 191     const std::string& security_info) {
 192   // Upon completion, act like a pass-through handler in case the downstream
 193   // handler defers OnResponseCompleted.
 194   state_ = STATE_STREAMING;
 195
 196   return next_handler_->OnResponseCompleted(request_id, status, security_info);
 197 }
 198
 199 void BufferedResourceHandler::Resume() {
 200   switch (state_) {
 201     case STATE_BUFFERING:
 202     case STATE_PROCESSING:
 203       NOTREACHED();
 204       break;
 205     case STATE_REPLAYING:
 206       base::MessageLoop::current()->PostTask(
 207           FROM_HERE,
 208           base::Bind(&BufferedResourceHandler::CallReplayReadCompleted,
 209                      weak_ptr_factory_.GetWeakPtr()));
 210       break;
 211     case STATE_STARTING:
 212     case STATE_STREAMING:
 213       controller()->Resume();
 214       break;
 215   }
 216 }
 217
 218 void BufferedResourceHandler::Cancel() {
 219   controller()->Cancel();
 220 }
 221
 222 void BufferedResourceHandler::CancelAndIgnore() {
 223   controller()->CancelAndIgnore();
 224 }
 225
 226 void BufferedResourceHandler::CancelWithError(int error_code) {
 227   controller()->CancelWithError(error_code);
 228 }
 229
 230 bool BufferedResourceHandler::ProcessResponse(bool* defer) {
 231   DCHECK_EQ(STATE_PROCESSING, state_);
 232
 233   // TODO(darin): Stop special-casing 304 responses.
 234   if (!(response_->head.headers.get() &&
 235         response_->head.headers->response_code() == 304)) {
 236     if (!SelectNextHandler(defer))
 237       return false;
 238     if (*defer)
 239       return true;
 240   }
 241
 242   state_ = STATE_REPLAYING;
 243
 244   if (!next_handler_->OnResponseStarted(GetRequestID(), response_.get(), defer))
 245     return false;
 246
 247   if (!read_buffer_.get()) {
 248     state_ = STATE_STREAMING;
 249     return true;
 250   }
 251
 252   if (!*defer)
 253     return ReplayReadCompleted(defer);
 254
 255   return true;
 256 }
 257
 258 bool BufferedResourceHandler::ShouldSniffContent() {
 259   const std::string& mime_type = response_->head.mime_type;
 260
 261   std::string content_type_options;
 262   request()->GetResponseHeaderByName("x-content-type-options",
 263                                      &content_type_options);
 264
 265   bool sniffing_blocked =
 266       LowerCaseEqualsASCII(content_type_options, "nosniff");
 267   bool we_would_like_to_sniff =
 268       net::ShouldSniffMimeType(request()->url(), mime_type);
 269
 270   RecordSnifferMetrics(sniffing_blocked, we_would_like_to_sniff, mime_type);
 271
 272   if (!sniffing_blocked && we_would_like_to_sniff) {
 273     // We're going to look at the data before deciding what the content type
 274     // is.  That means we need to delay sending the ResponseStarted message
 275     // over the IPC channel.
 276     VLOG(1) << "To buffer: " << request()->url().spec();
 277     return true;
 278   }
 279
 280   return false;
 281 }
 282
 283 bool BufferedResourceHandler::DetermineMimeType() {
 284   DCHECK_EQ(STATE_BUFFERING, state_);
 285
 286   const std::string& type_hint = response_->head.mime_type;
 287
 288   std::string new_type;
 289   bool made_final_decision =
 290       net::SniffMimeType(read_buffer_->data(), bytes_read_, request()->url(),
 291                          type_hint, &new_type);
 292
 293   // SniffMimeType() returns false if there is not enough data to determine
 294   // the mime type. However, even if it returns false, it returns a new type
 295   // that is probably better than the current one.
 296   response_->head.mime_type.assign(new_type);
 297
 298   return made_final_decision;
 299 }
 300
 301 bool BufferedResourceHandler::SelectNextHandler(bool* defer) {
 302   DCHECK(!response_->head.mime_type.empty());
 303
 304   ResourceRequestInfoImpl* info = GetRequestInfo();
 305   const std::string& mime_type = response_->head.mime_type;
 306
 307   if (net::IsSupportedCertificateMimeType(mime_type)) {
 308     // Install certificate file.
 309     scoped_ptr<ResourceHandler> handler(
 310         new CertificateResourceHandler(request()));
 311     return UseAlternateNextHandler(handler.Pass());
 312   }
 313
 314   if (!info->allow_download())
 315     return true;
 316
 317   bool must_download = MustDownload();
 318   if (!must_download) {
 319     if (net::IsSupportedMimeType(mime_type))
 320       return true;
 321
 322     scoped_ptr<ResourceHandler> handler(
 323         host_->MaybeInterceptAsStream(request(), response_.get()));
 324     if (handler)
 325       return UseAlternateNextHandler(handler.Pass());
 326
 327 #if defined(ENABLE_PLUGINS)
 328     bool stale;
 329     bool has_plugin = HasSupportingPlugin(&stale);
 330     if (stale) {
 331       // Refresh the plugins asynchronously.
 332       PluginServiceImpl::GetInstance()->GetPlugins(
 333           base::Bind(&BufferedResourceHandler::OnPluginsLoaded,
 334                      weak_ptr_factory_.GetWeakPtr()));
 335       *defer = true;
 336       return true;
 337     }
 338     if (has_plugin)
 339       return true;
 340 #endif
 341   }
 342
 343   // Install download handler
 344   info->set_is_download(true);
 345   scoped_ptr<ResourceHandler> handler(
 346       host_->CreateResourceHandlerForDownload(
 347           request(),
 348           true,  // is_content_initiated
 349           must_download,
 350           content::DownloadItem::kInvalidId,
 351           scoped_ptr<DownloadSaveInfo>(new DownloadSaveInfo()),
 352           DownloadUrlParameters::OnStartedCallback()));
 353   return UseAlternateNextHandler(handler.Pass());
 354 }
 355
 356 bool BufferedResourceHandler::UseAlternateNextHandler(
 357     scoped_ptr<ResourceHandler> new_handler) {
 358   if (response_->head.headers.get() &&  // Can be NULL if FTP.
 359       response_->head.headers->response_code() / 100 != 2) {
 360     // The response code indicates that this is an error page, but we don't
 361     // know how to display the content.  We follow Firefox here and show our
 362     // own error page instead of triggering a download.
 363     // TODO(abarth): We should abstract the response_code test, but this kind
 364     //               of check is scattered throughout our codebase.
 365     request()->CancelWithError(net::ERR_FILE_NOT_FOUND);
 366     return false;
 367   }
 368
 369   int request_id = GetRequestID();
 370
 371   // Inform the original ResourceHandler that this will be handled entirely by
 372   // the new ResourceHandler.
 373   // TODO(darin): We should probably check the return values of these.
 374   bool defer_ignored = false;
 375   next_handler_->OnResponseStarted(request_id, response_.get(), &defer_ignored);
 376   DCHECK(!defer_ignored);
 377   net::URLRequestStatus status(net::URLRequestStatus::CANCELED,
 378                                net::ERR_ABORTED);
 379   next_handler_->OnResponseCompleted(request_id, status, std::string());
 380
 381   // This is handled entirely within the new ResourceHandler, so just reset the
 382   // original ResourceHandler.
 383   next_handler_ = new_handler.Pass();
 384   next_handler_->SetController(this);
 385
 386   return CopyReadBufferToNextHandler(request_id);
 387 }
 388
 389 bool BufferedResourceHandler::ReplayReadCompleted(bool* defer) {
 390   DCHECK(read_buffer_.get());
 391
 392   bool result = next_handler_->OnReadCompleted(GetRequestID(), bytes_read_,
 393                                                defer);
 394
 395   read_buffer_ = NULL;
 396   read_buffer_size_ = 0;
 397   bytes_read_ = 0;
 398
 399   state_ = STATE_STREAMING;
 400
 401   return result;
 402 }
 403
 404 void BufferedResourceHandler::CallReplayReadCompleted() {
 405   bool defer = false;
 406   if (!ReplayReadCompleted(&defer)) {
 407     controller()->Cancel();
 408   } else if (!defer) {
 409     state_ = STATE_STREAMING;
 410     controller()->Resume();
 411   }
 412 }
 413
 414 bool BufferedResourceHandler::MustDownload() {
 415   if (must_download_is_set_)
 416     return must_download_;
 417
 418   must_download_is_set_ = true;
 419
 420   std::string disposition;
 421   request()->GetResponseHeaderByName("content-disposition", &disposition);
 422   if (!disposition.empty() &&
 423       net::HttpContentDisposition(disposition, std::string()).is_attachment()) {
 424     must_download_ = true;
 425   } else if (host_->delegate() &&
 426              host_->delegate()->ShouldForceDownloadResource(
 427                  request()->url(), response_->head.mime_type)) {
 428     must_download_ = true;
 429   } else {
 430     must_download_ = false;
 431   }
 432
 433   return must_download_;
 434 }
 435
 436 bool BufferedResourceHandler::HasSupportingPlugin(bool* stale) {
 437   ResourceRequestInfoImpl* info = GetRequestInfo();
 438
 439   bool allow_wildcard = false;
 440   WebPluginInfo plugin;
 441   return PluginServiceImpl::GetInstance()->GetPluginInfo(
 442       info->GetChildID(), info->GetRouteID(), info->GetContext(),
 443       request()->url(), GURL(), response_->head.mime_type, allow_wildcard,
 444       stale, &plugin, NULL);
 445 }
 446
 447 bool BufferedResourceHandler::CopyReadBufferToNextHandler(int request_id) {
 448   if (!bytes_read_)
 449     return true;
 450
 451   scoped_refptr<net::IOBuffer> buf;
 452   int buf_len = 0;
 453   if (!next_handler_->OnWillRead(request_id, &buf, &buf_len, bytes_read_))
 454     return false;
 455
 456   CHECK((buf_len >= bytes_read_) && (bytes_read_ >= 0));
 457   memcpy(buf->data(), read_buffer_->data(), bytes_read_);
 458   return true;
 459 }
 460
 461 void BufferedResourceHandler::OnPluginsLoaded(
 462     const std::vector<WebPluginInfo>& plugins) {
 463   bool defer = false;
 464   if (!ProcessResponse(&defer)) {
 465     controller()->Cancel();
 466   } else if (!defer) {
 467     controller()->Resume();
 468   }
 469 }
 470
 471 }  // namespace content