Initial implementation for CertNetFetcher.

net/cert/cert_net_fetcher.h

+// Copyright 2015 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 NET_CERT_CERT_NET_FETCHER_H_
+#define NET_CERT_CERT_NET_FETCHER_H_
+
+#include <set>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "net/base/net_errors.h"
+#include "net/base/net_export.h"
+#include "url/gurl.h"

[Ryan Sleevi, 2015/03/25 06:16:37]

Can forward declare

[eroman, 2015/03/26 03:50:49]

Done.

+
+namespace net {
+
+class URLRequestContext;
+
+// CertNetFetcher is a helper for fetching AIA URLs and CRL URLs.
+//
+// It manages the outstanding requests, and applies policies specific to
+// certificate network fetches. For instance:
+//   * Enforces a maximum timeout on responses
+//   * Enforces a maximum size on responses
+//   * Restricts URLs to http://
+//
+// The CertNetFetcher is initialized by giving it a URLRequestContext for the
+// network dependencies. Note that it does not maintain its own in-memory cache
+// for responses. Instead it is reliant on the URLRequestContext providing an
+// HTTP cache if this is desired.
+//
+// -------------------------
+// Cancellation of requests
+// -------------------------
+//
+//  * Network requests started by the CertNetFetcher can be cancelled using
+//    CancelRequest(). Cancellation means the callback will not be invoked.
+//
+//  * If the CertNetFetcher is deleted then any outstanding
+//    requests are automatically cancelled.
+//
+//  * Cancelling a request more than once is an error (and may result in a
+//    use-after-free).
+//
+//  * Cancelling a request within the execution of a callback is allowed.
+//
+//  * Deleting the CertNetFetcher from within the execution of a callback is
+//    allowed.
+//
+// -------------------------
+// Threading
+// -------------------------
+//
+// The CertNetFetcher is expected to be operated from a single thread, which has
+// an IO message loop. The URLRequestContext will be accessed from this same
+// thread, and callbacks will be posted to this message loop.
+//
+// For more details see the early design document:
+//   https://docs.google.com/a/chromium.org/document/d/1CdS9YOnPdAyVZBJqHY7ZJ6tUlU71OCvX8kHnaVhf144/edit
+class NET_EXPORT CertNetFetcher {
+ private:
+  struct Request;
+
+ public:
+  using FetchCallback =
+      base::Callback<void(Error, const std::vector<uint8_t>&)>;
+  using RequestId = Request*;
+
+  // This value can be used in place of timeout or max size limits.
+  static const int DEFAULT = -1;

[Ryan Sleevi, 2015/03/25 06:16:37]

So this syntax is super sketch (there's some old chromium-dev threads that
explain why; TL;DR - static storage needs to be filled in the .cc for MSVC, but
that can make gcc/clang grumpy)

You could use an enum of int type here, since the enum will promote.

[eroman, 2015/03/26 03:50:49]

Interesting, I have gotten the opposite feedback from other developers, asking
me to turn my enum hack into static const on reviews, claiming that the compiler
issues are no more.

(Will see if I can find that review. I think it was blink side from abarth, but
could be wrong)

OK, I will go ahead and enumify it, its all the same to me.

+
+  // Initializes CertNetFetcher using the specified URLRequestContext for
+  // issuing requests. |context| must remain valid for the entire lifetime of
+  // the CertNetFetcher.
+  explicit CertNetFetcher(URLRequestContext* context);
+
+  // Deletion implicitly cancels any outstanding requests.
+  ~CertNetFetcher();
+
+  // Cancels the indicated request. It is an error to call this function on a
+  // request which has already completed (including one that was already
+  // cancelled).
+  void CancelRequest(RequestId request);
+
+  // The Fetch*() methods start an asynchronous request which can be cancelled
+  // using RequestId. Here is the meaning of the common parameters:
+  //
+  //   * url -- The http:// URL to fetch.
+  //   * timeout_seconds -- The maximum allowed duration for the fetch job. If
+  //         this delay is exceeded then the request will fail. To use a default
+  //         timeout pass DEFAULT.
+  //   * max_response_bytes -- The maximum size of the response body. If this
+  //     size is exceeded then the request will fail. To use a default timeout
+  //     pass DEFAULT.
+  //   * callback -- The callback that will be invoked on completion of the job.
+
+  RequestId FetchCaIssuers(const GURL& url,
+                           int timeout_milliseconds,
+                           int max_response_bytes,
+                           const FetchCallback& callback);
+
+  RequestId FetchCrl(const GURL& url,
+                     int timeout_milliseconds,
+                     int max_response_bytes,
+                     const FetchCallback& callback);
+
+  RequestId FetchOcsp(const GURL& url,
+                      int timeout_milliseconds,
+                      int max_response_bytes,
+                      const FetchCallback& callback);
+
+ private:
+  class Job;
+  struct JobToRequestParamsComparator;
+  struct RequestParams;
+
+  struct JobComparator {
+    bool operator()(const Job* job1, const Job* job2) const;
+  };
+
+  using JobSet = std::set<Job*, JobComparator>;
+
+  // Starts an asynchronous request to fetch the given URL. On completion
+  // |callback| will be invoked.
+  //
+  // Completion of the request will never occur synchronously. In other words it
+  // is guaranteed that |callback| will only be invoked once the Fetch*() method
+  // has returned.
+  RequestId Fetch(scoped_ptr<RequestParams> request_params,
+                  const FetchCallback& callback);
+
+  // Finds a job with a matching RequestPararms or returns NULL if there was no
+  // match.
+  Job* FindJob(const RequestParams& params);
+
+  // Removes |job| from the in progress jobs and transfers ownership to the
+  // caller.
+  scoped_ptr<Job> RemoveJob(Job* job);
+
+  // Indicates which Job is currently executing inside of OnJobCompleted().
+  void SetCurrentlyCompletingJob(Job* job);
+
+  // The in-progress jobs. This set does not contain the job which is actively
+  // invoking callbacks (OnJobCompleted). Instead that is tracked by
+  // |currently_completing_job_|.
+  JobSet jobs_;
+
+  // The Job that is currently executing OnJobCompleted(). There can be at most
+  // one such job. This pointer is not owned.
+  Job* currently_completing_job_;
+
+  // Not owned. CertNetFetcher must outlive the URLRequestContext.
+  URLRequestContext* context_;
+
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(CertNetFetcher);
+};
+
+}  // namespace net
+
+#endif  // NET_CERT_CERT_NET_FETCHER_H_