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// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <memory>
#include <string>
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "content/browser/loader/layered_resource_handler.h"
#include "content/browser/loader/resource_controller.h"
#include "content/browser/loader/resource_handler.h"
#include "content/common/content_export.h"
#include "net/base/io_buffer.h"
#include "net/url_request/url_request_status.h"
namespace net {
class URLRequest;
namespace content {
class ResourceController;
// ResourceHandler that initiates special handling of the response if needed,
// based on the response's MIME type (starts downloads, sends data to some
// plugin types via a special channel).
// An InterceptingResourceHandler holds two handlers (|next_handler| and
// |new_handler|). It assumes the following:
// - OnResponseStarted on |next_handler| never sets |*defer|.
// - OnResponseCompleted on |next_handler| never sets |*defer|.
class CONTENT_EXPORT InterceptingResourceHandler
: public LayeredResourceHandler {
InterceptingResourceHandler(std::unique_ptr<ResourceHandler> next_handler,
net::URLRequest* request);
~InterceptingResourceHandler() override;
// ResourceHandler implementation:
void OnResponseStarted(
network::ResourceResponse* response,
std::unique_ptr<ResourceController> controller) override;
void OnWillRead(scoped_refptr<net::IOBuffer>* buf,
int* buf_size,
std::unique_ptr<ResourceController> controller) override;
void OnReadCompleted(int bytes_read,
std::unique_ptr<ResourceController> controller) override;
void OnResponseCompleted(
const net::URLRequestStatus& status,
std::unique_ptr<ResourceController> controller) override;
// Replaces the next handler with |new_handler|, sending
// |payload_for_old_handler| to the old handler. Must be called after
// OnWillStart and OnRequestRedirected and before OnResponseStarted. One
// OnWillRead call is permitted beforehand. |new_handler|'s OnWillStart and
// OnRequestRedirected methods will not be called.
void UseNewHandler(std::unique_ptr<ResourceHandler> new_handler,
const std::string& payload_for_old_handler);
// Used in tests.
ResourceHandler* new_handler_for_testing() const {
return new_handler_.get();
// ResourceController subclass that calls into the InterceptingResourceHandler
// on cancel/resume.
class Controller;
enum class State {
// The InterceptingResourceHandler is waiting for the mime type of the
// response to be identified, to check if the next handler should be
// replaced with an appropriate one.
// The InterceptingResourceHandler is starting the process of swapping
// handlers.
// States where the InterceptingResourceHandler passes the initial
// OnWillRead call to the old handler, and then waits for the resulting
// buffer read buffer.
// The InterceptingResourceHandler is sending the payload given via
// UseNewHandler to the old handler. The first state starts retrieving a
// buffer from the old handler, the second state copies as much of the data
// as possible to the received buffer and passes it to the old handler.
// The InterceptingResourcHandler is calling the new handler's
// OnResponseStarted method and waiting for its completion via Resume().
// After completion, the InterceptingResourceHandler will transition to
// The InterceptingResourcHandler is calling the new handler's
// OnResponseStarted method and waiting for its completion via Resume().
// After completion, the InterceptingResourceHandler will transition to
// The InterceptingResourcHandler is waiting for OnReadCompleted to be
// called.
// The two phases of uploading previously received data stored in
// |first_read_buffer_double_| to the new handler, which is now stored in
// |next_handler_|. The first state gets a buffer to write to, and the next
// copies all the data it can to that buffer.
// The InterceptingResourceHandler has replaced its next ResourceHandler if
// needed, and has ensured the buffered read data was properly transmitted
// to the new ResourceHandler. The InterceptingResourceHandler now acts as
// a pass-through ResourceHandler.
// Runs necessary operations depending on |state_|.
void DoLoop();
void ResumeInternal();
void SendOnWillReadToOldHandler();
void OnBufferReceived();
void SendOnResponseStartedToOldHandler();
void SendPayloadToOldHandler();
void ReceivedBufferFromOldHandler();
void SendFirstReadBufferToNewHandler();
void SendOnResponseStartedToNewHandler();
void ReceivedBufferFromNewHandler();
State state_ = State::STARTING;
std::unique_ptr<ResourceHandler> new_handler_;
std::string payload_for_old_handler_;
size_t payload_bytes_written_ = 0;
// Result of the first read, that may have to be passed to an alternate
// ResourceHandler instead of the original ResourceHandler.
scoped_refptr<net::IOBuffer> first_read_buffer_;
// Instead of |first_read_buffer_|, this handler creates an IOBuffer with
// the same size and return it to the client.
scoped_refptr<net::IOBuffer> first_read_buffer_double_;
int first_read_buffer_size_ = 0;
int first_read_buffer_bytes_read_ = 0;
int first_read_buffer_bytes_written_ = 0;
// Information about the new handler's buffer while copying data from
// |first_read_buffer_double_| to the new handler's buffer.
// Note that when these are used, the old handler has been destroyed, and
// |next_handler_| is now the new one.
scoped_refptr<net::IOBuffer> new_handler_read_buffer_;
int new_handler_read_buffer_size_ = 0;
// Pointers to parent-owned read buffer and its size. Only used for first
// OnWillRead call.
scoped_refptr<net::IOBuffer>* parent_read_buffer_ = nullptr;
int* parent_read_buffer_size_ = nullptr;
scoped_refptr<network::ResourceResponse> response_;
// Next two values are used to handle synchronous Resume calls without a
// PostTask.
// True if the code is currently within a DoLoop.
bool in_do_loop_ = false;
// True if the request was resumed while |in_do_loop_| was true;
bool advance_to_next_state_ = false;
base::WeakPtrFactory<InterceptingResourceHandler> weak_ptr_factory_;
} // namespace content