Disk Based Certificate Cache Implementation

net/cert_cache/disk_based_cert_cache.h

+// Copyright (c) 2014 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_CACHE_DISK_BASED_CERT_CACHE_H
+#define NET_CERT_CACHE_DISK_BASED_CERT_CACHE_H
+
+#include <string>
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "net/base/completion_callback.h"
+#include "net/base/net_export.h"
+#include "net/cert/x509_certificate.h"
+#include "net/disk_cache/disk_cache.h"
+
+namespace net {
+
+class NET_EXPORT_PRIVATE DiskBasedCertCache {
+ public:
+  explicit DiskBasedCertCache(disk_cache::Backend* backend);
+  ~DiskBasedCertCache();
+
+  // Fetches the certificate associated with |key|. If the certificate is
+  // found within the cache, |cb| will be called with the certificate.
+  // Otherwise, |cb| will be called with NULL.
+  void Get(std::string& key,
+           base::Callback<void(X509Certificate::OSCertHandle cert_handle)> cb);

[Ryan Sleevi, 2014/06/11 22:00:09]

Crap, I just realized a problem with this Callback API.

If the Callback doesn't run (eg: because it's bound to a WeakPtr), then we'd end
up leaking a reference to the |cert_handle|.

This doesn't change the API we need to expose, just requires a little trickery
with how we call the callback.

+
+  // Stores |handle| in the cache. If |handle| is successfully stored, |cb|
+  // will be called with the key. If |cb| is called with an empty std::string,
+  // then |handle| was not stored.
+  void Set(const X509Certificate::OSCertHandle cert_handle,
+           base::Callback<void(const std::string&)> cb);
+
+ private:
+  // State for the current operation, NONE indicates no pending operation.
+  // Will have to be updated to accomodate multiple simultaneous operations.
+  enum State { START_WRITE, FINISH_WRITE, START_READ, FINISH_READ, NONE };
+
+  std::string Key();
+  std::string Serialize();
+  void OnIOComplete(int rv);
+  void DoStartWrite();
+  void DoFinishWrite();
+  void DoStartRead();
+  void DoFinishRead();
+
+  void reset_state();
+
+  // Most of these data members will have to be changed in the near future
+  // to accommodate for simultaneous operation.
+  disk_cache::Backend* backend_;
+  disk_cache::Entry* active_entry_;
+  base::WeakPtrFactory<DiskBasedCertCache> weak_factory_;

[Ryan Sleevi, 2014/06/11 22:00:09]

WeakPtrFactory should always be the last member of the class. See
https://code.google.com/p/chromium/issues/detail?id=303818

+  CompletionCallback io_callback_;
+  State state_;
+
+  X509Certificate::OSCertHandle active_cert_handle_;
+  int active_entry_size_;
+  scoped_refptr<IOBuffer> buffer;
+  base::Callback<void(const std::string&)> user_write_callback_;
+  base::Callback<void(X509Certificate::OSCertHandle cert_handle)>
+      user_read_callback_;
+};
+
+}  // namespace
+
+#endif  // NET_CERT_CACHE_DISK_BASED_CERT_CACHE_H