DevTools protocol interception, blocking & modification of requests

content/browser/devtools/devtools_url_interceptor_request_job.h

+// Copyright 2017 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.
+
+#ifndef CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_URL_INTERCEPTOR_REQUEST_JOB_H_
+#define CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_URL_INTERCEPTOR_REQUEST_JOB_H_
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/single_thread_task_runner.h"
+#include "content/browser/devtools/devtools_url_request_interceptor.h"
+#include "content/browser/devtools/protocol/network.h"
+#include "content/public/browser/browser_thread.h"
+#include "net/url_request/url_request.h"
+#include "net/url_request/url_request_job.h"
+
+namespace net {
+class UploadElementReader;
+}
+
+namespace content {
+
+// A URLRequestJob that allows programmatic request blocking / modification or
+// response mocking.  This class should only be accessed on the IO thread.
+class DevToolsURLInterceptorRequestJob : public net::URLRequestJob,
+                                         public net::URLRequest::Delegate {
+ public:
+  DevToolsURLInterceptorRequestJob(
+      base::WeakPtr<DevToolsURLRequestInterceptor::State>
+          devtools_url_request_interceptor_state,
+      const std::string& intercept_id,
+      net::URLRequest* original_request,
+      net::NetworkDelegate* original_network_delegate,
+      base::WeakPtr<protocol::NetworkHandler> network_handler,
+      bool is_redirect);
+
+  ~DevToolsURLInterceptorRequestJob() override;
+
+  // net::URLRequestJob implementation:
+  void SetExtraRequestHeaders(const net::HttpRequestHeaders& headers) override;
+  void Start() override;
+  void Kill() override;
+  int ReadRawData(net::IOBuffer* buf, int buf_size) override;
+  int GetResponseCode() const override;
+  void GetResponseInfo(net::HttpResponseInfo* info) override;
+  bool GetMimeType(std::string* mime_type) const override;
+  bool GetCharset(std::string* charset) override;
+  void GetLoadTimingInfo(net::LoadTimingInfo* load_timing_info) const override;
+
+  // net::URLRequest::Delegate methods:
+  void OnAuthRequired(net::URLRequest* request,
+                      net::AuthChallengeInfo* auth_info) override;
+  void OnSSLCertificateError(net::URLRequest* request,
+                             const net::SSLInfo& ssl_info,
+                             bool fatal) override;
+  void OnResponseStarted(net::URLRequest* request, int net_error) override;
+  void OnReadCompleted(net::URLRequest* request, int bytes_read) override;
+  void OnReceivedRedirect(net::URLRequest* request,
+                          const net::RedirectInfo& redirect_info,
+                          bool* defer_redirect) override;
+
+  DevToolsURLRequestInterceptor::CommandStatus AllowRequest();
+  DevToolsURLRequestInterceptor::CommandStatus BlockRequest(
+      net::Error error_reason);
+  DevToolsURLRequestInterceptor::CommandStatus ModifyRequest(
+      std::unique_ptr<DevToolsURLRequestInterceptor::Modifications>
+          modifications);
+  DevToolsURLRequestInterceptor::CommandStatus MockResponse(
+      std::string raw_response);

[Sami, 2017/05/19 17:15:43]

nit: const ref

[alex clarke (OOO till 29th), 2017/05/23 15:46:55]

Can't do that safely since this is called via posttask and the source would be
out of scope.

+
+ private:
+  class SubRequest;
+
+  // We keep a copy of the original request details to facilitate the
+  // Network.modifyRequest command which could potentially change any of these
+  // fields.
+  struct RequestDetails {
+    RequestDetails(const GURL& url,
+                   const std::string& method,
+                   std::unique_ptr<net::UploadElementReader> post_data,
+                   const net::HttpRequestHeaders& extra_request_headers,
+                   const net::RequestPriority& priority,
+                   const net::URLRequestContext* url_request_context);
+    ~RequestDetails();
+
+    GURL url;
+    std::string method;
+    std::unique_ptr<net::UploadElementReader> post_data;
+    net::HttpRequestHeaders extra_request_headers;
+    net::RequestPriority priority;
+    const net::URLRequestContext* url_request_context;
+  };
+
+  // If the request was either allowed or modified, a SubRequest will be used to
+  // perform the fetch and the results proxied to the original request.  This
+  // gives us the flexibility to pretend redirects didn't happen if the user
+  // chooses to mock the response.

[Sami, 2017/05/19 17:15:43]

Maybe also worth mentioning that the subrequest isn't visible to the interceptor
(or is it?)

[alex clarke (OOO till 29th), 2017/05/23 15:46:56]

Done.

+  class SubRequest {
+   public:
+    SubRequest(
+        DevToolsURLInterceptorRequestJob::RequestDetails& request_details,
+        DevToolsURLInterceptorRequestJob* devtools_interceptor_request_job);
+    ~SubRequest();
+
+    void Cancel();
+
+    net::URLRequest* request() const { return request_.get(); }
+
+   private:
+    std::unique_ptr<net::URLRequest> request_;
+
+    DevToolsURLInterceptorRequestJob*
+        devtools_interceptor_request_job_;  // NOT OWNED.
+
+    base::WeakPtr<DevToolsURLRequestInterceptor::State>
+        devtools_url_request_interceptor_state_;
+    bool fetch_in_progress_;
+  };
+
+  class MockResponseDetails {
+   public:
+    MockResponseDetails(std::string response_bytes,
+                        base::TimeTicks response_time);
+
+    MockResponseDetails(
+        const scoped_refptr<net::HttpResponseHeaders>& response_headers,
+        std::string response_bytes,
+        size_t read_offset,
+        base::TimeTicks response_time);
+
+    ~MockResponseDetails();
+
+    const scoped_refptr<net::HttpResponseHeaders>& response_headers() const {

[Sami, 2017/05/19 17:15:43]

nit: Maybe just return net::HttpResponseHeaders* since the caller isn't expected
to retain a reference

[alex clarke (OOO till 29th), 2017/05/23 15:46:55]

Actually that's exactly what DevToolsURLInterceptorRequestJob::GetResponseInfo
does.

+      return response_headers_;
+    }
+
+    base::TimeTicks response_time() const { return response_time_; }
+
+    int ReadRawData(net::IOBuffer* buf, int buf_size);
+
+   private:
+    scoped_refptr<net::HttpResponseHeaders> response_headers_;
+    std::string response_bytes_;
+    size_t read_offset_;
+    base::TimeTicks response_time_;
+  };
+
+  // Retrieves the response headers from either the |sub_request_| or the
+  // |mock_response_|.  In some cases (e.g. file access) this may be null.
+  const net::HttpResponseHeaders* GetHttpResponseHeaders() const;
+
+  void DispatchError(net::Error reason);
+  void SendInterceptedRequestEventOnUiThread();
+  void SendInterceptedRedirectEventOnUiThread(
+      protocol::DictionaryValue* headers_dict,
+      int http_status_code,
+      std::string redirect_url);

[Sami, 2017/05/19 17:15:43]

nit: const ref

[alex clarke (OOO till 29th), 2017/05/23 15:46:56]

Can't do that due to PostTask and the source going out of scope.

+
+  base::WeakPtr<DevToolsURLRequestInterceptor::State>
+      devtools_url_request_interceptor_state_;
+  RequestDetails request_details_;
+  std::unique_ptr<SubRequest> sub_request_;
+  std::unique_ptr<MockResponseDetails> mock_response_details_;
+  std::unique_ptr<net::RedirectInfo> redirect_;
+  bool waiting_for_user_response_;

[Sami, 2017/05/19 17:15:43]

Uninitialized?

[alex clarke (OOO till 29th), 2017/05/23 15:46:56]

Done.

+
+  const std::string intercept_id_;
+  base::WeakPtr<protocol::NetworkHandler> network_handler_;
+  const scoped_refptr<base::SingleThreadTaskRunner> io_thread_task_runner_;
+  const bool is_redirect_;
+  base::WeakPtrFactory<DevToolsURLInterceptorRequestJob> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(DevToolsURLInterceptorRequestJob);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_URL_INTERCEPTOR_REQUEST_JOB_H_