Certificate Transparency: Add STH Fetching capability.

components/certificate_transparency/log_proof_fetcher.h

Index: components/certificate_transparency/log_proof_fetcher.h
diff --git a/components/certificate_transparency/log_proof_fetcher.h b/components/certificate_transparency/log_proof_fetcher.h
new file mode 100644
index 0000000000000000000000000000000000000000..8603b31aec388531d2879073f622edff9d460d0a
--- /dev/null
+++ b/components/certificate_transparency/log_proof_fetcher.h
@@ -0,0 +1,86 @@
+// 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 COMPONENTS_CERTIFICATE_TRANSPARENCY_LOG_PROOF_FETCHER_H_
+#define COMPONENTS_CERTIFICATE_TRANSPARENCY_LOG_PROOF_FETCHER_H_
+
+#include <map>
+#include <string>
+
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "net/url_request/url_request.h"
+#include "url/gurl.h"
+
+namespace base {
+class Value;
+}  // namespace base
+
+namespace net {

[davidben, 2015/07/16 21:53:39]

Nit: Probably put a newline after this to mirror line 26.

[Eran Messeri, 2015/07/17 15:40:23]

Done.

+class URLRequestContext;
+
+namespace ct {
+struct SignedTreeHead;
+}  // namespace ct
+
+}  // namespace net
+
+namespace certificate_transparency {
+
+// Fetches STHs and consistency proofs from Certificate Transparency logs
+// using the URLRequestContext provided during the instance construction.
+class LogProofFetcher : public net::URLRequest::Delegate {
+ public:
+  typedef base::Callback<void(const std::string&,
+                              const net::ct::SignedTreeHead&)> FetchSTHCallback;
+  typedef base::Callback<void(const std::string&, const std::string&)>

[davidben, 2015/07/16 21:53:39]

Nit:
  using FetchSTHCallback = base::Callback<..>;
(as well as the other)

[Eran Messeri, 2015/07/17 15:40:23]

Done.

+      FetchFailedCallback;
+  explicit LogProofFetcher(net::URLRequestContext* request_context);
+  ~LogProofFetcher() override;
+
+  // Fetch the latest Signed Tree Head from the log identified by |log_id|
+  // from |log_url|.
+  void FetchSTH(const GURL& log_url,
+                const std::string& log_id,
+                FetchSTHCallback fetched_cb,
+                FetchFailedCallback failed_cb);
+
+  // net::URLRequest::Delegate
+  void OnResponseStarted(net::URLRequest* request) override;
+  void OnReadCompleted(net::URLRequest* request, int bytes_read) override;
+
+ private:
+  struct FetchParams;
+
+  bool CheckReadStatus(net::URLRequest* request, FetchParams* params);
+  void KickOffARead(net::URLRequest* request, FetchParams* params);
+
+  // Performs post-report cleanup.
+  void RequestComplete(net::URLRequest* request);
+  // Returns the FetchParams associated with the request. The caller takes
+  // ownership of the returned value in case the params should be used before
+  // being deleted.
+  scoped_ptr<FetchParams> CleanupRequest(net::URLRequest* request);
+
+  // Actually create the request
+  scoped_ptr<net::URLRequest> CreateURLRequest(const GURL& fetch_sth_url);
+
+  // Callbacks for parsing the STH's JSON by the SafeJsonParser
+  void OnSTHJsonParseSuccess(FetchParams params,
+                             scoped_ptr<base::Value> parsed_json);
+  void OnSTHJsonParseError(FetchParams params, const std::string& error);
+
+  net::URLRequestContext* const request_context_;
+
+  // Owns the contained requests.

[davidben, 2015/07/16 21:53:39]

This also owns the FetchParams, right? So probably mention both.

[Eran Messeri, 2015/07/17 15:40:23]

Done.

+  std::map<net::URLRequest*, FetchParams*> inflight_requests_;
+
+  base::WeakPtrFactory<LogProofFetcher> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(LogProofFetcher);
+};
+
+}  // namespace certificate_transparency
+
+#endif  // COMPONENTS_CERTIFICATE_TRANSPARENCY_LOG_PROOF_FETCHER_H_