Certificate Transparency: Fetching of Signed Tree Heads (DRAFT)

components/certificate_transparency/log_proof_fetcher.cc

Index: components/certificate_transparency/log_proof_fetcher.cc
diff --git a/components/certificate_transparency/log_proof_fetcher.cc b/components/certificate_transparency/log_proof_fetcher.cc
new file mode 100644
index 0000000000000000000000000000000000000000..9e70f1414fd1b2e29ce1e45fc1af4dacb3a5b119
--- /dev/null
+++ b/components/certificate_transparency/log_proof_fetcher.cc
@@ -0,0 +1,185 @@
+// 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.
+
+#include "components/certificate_transparency/log_proof_fetcher.h"
+
+#include "base/logging.h"
+#include "base/stl_util.h"
+#include "base/strings/string_piece.h"
+#include "base/values.h"
+#include "components/certificate_transparency/log_response_parser.h"
+#include "components/safe_json_parser/safe_json_parser.h"
+#include "net/base/load_flags.h"
+#include "net/base/request_priority.h"
+#include "net/cert/ct_log_verifier.h"
+#include "net/cert/signed_tree_head.h"
+#include "net/url_request/url_request_context.h"
+
+const int kMaxSTHSizeInBytes = 600;
+
+namespace certificate_transparency {
+
+struct LogProofFetcher::FetchParams {
+  explicit FetchParams(const std::string& id, FetchSTHCallback callback);
+  ~FetchParams();
+
+  std::string log_id;
+  FetchSTHCallback fetched_callback;
+  scoped_refptr<net::IOBufferWithSize> sth_buffer;
+  int read_bytes;
+};
+
+LogProofFetcher::LogProofFetcher(net::URLRequestContext* request_context)
+    : request_context_(request_context), weak_factory_(this) {
+  DCHECK(request_context);
+}
+
+LogProofFetcher::~LogProofFetcher() {
+  for (auto it = inflight_requests_.begin(); it != inflight_requests_.end();

[Ryan Sleevi, 2015/06/29 11:58:13]

const auto& ||

for (inflight_request : inflight_requests_) {
  inflight_request.first->cancel();
}

+       ++it)
+    it->first->Cancel();
+  STLDeleteContainerPairPointers(inflight_requests_.begin(),
+                                 inflight_requests_.end());
+}
+
+scoped_ptr<net::URLRequest> LogProofFetcher::CreateURLRequest(
+    const GURL& fetch_sth_url) {
+  DCHECK(request_context_);
+
+  scoped_ptr<net::URLRequest> request = request_context_->CreateRequest(
+      fetch_sth_url, net::DEFAULT_PRIORITY, this);
+  request->SetLoadFlags(net::LOAD_DO_NOT_SEND_COOKIES |

[Ryan Sleevi, 2015/06/29 11:58:13]

TBD: Whether or not we should send AUTH_DATA or any of the other load flags

+                        net::LOAD_DO_NOT_SAVE_COOKIES);
+  return request.Pass();
+}
+
+void LogProofFetcher::FetchSTH(const GURL& log_url,
+                               const std::string& log_id,
+                               FetchSTHCallback fetched_cb) {
+  GURL fetch_url(log_url.Resolve("ct/v1/get-sth"));
+  VLOG(1) << "About to fetch STH from " << fetch_url;
+  scoped_ptr<net::URLRequest> request = CreateURLRequest(fetch_url);
+
+  request->set_method("GET");
+
+  net::URLRequest* raw_request = request.get();
+  FetchParams* params = new FetchParams(log_id, fetched_cb);
+  inflight_requests_.insert(std::make_pair(request.release(), params));
+  raw_request->Start();
+}
+
+void LogProofFetcher::OnResponseStarted(net::URLRequest* request) {
+  const net::URLRequestStatus& status(request->status());
+  VLOG(1) << "Response started for fetch-sth from " << request->original_url();
+  if (!status.is_success()) {
+    LOG(WARNING) << "Fetching STH from " << request->original_url()
+                 << " failed. status:" << status.status()
+                 << " error:" << status.error();
+    CleanupRequest(request);
+  } else if (request->GetResponseCode() != 200) {
+    LOG(WARNING) << "Fetch STH HTTP status: " << request->GetResponseCode();
+    CleanupRequest(request);
+    return;
+  }
+
+  auto it(inflight_requests_.find(request));
+  DCHECK(it != inflight_requests_.end());
+  scoped_refptr<net::IOBufferWithSize> buffer(it->second->sth_buffer);
+  VLOG(1) << "Kicking off read.";
+  request->Read(buffer.get(), buffer->size(), &(it->second->read_bytes));
+  if (request->status().is_io_pending()) {
+    VLOG(1) << "IO Pending: Will wait.";
+    return;
+  } else {
+    VLOG(1) << "Data available: Invoking OnReadComplete.";
+    OnReadCompleted(request, it->second->read_bytes);
+  }
+}
+
+void LogProofFetcher::OnReadCompleted(net::URLRequest* request,
+                                      int bytes_read) {
+  VLOG(1) << "Read complete, got " << bytes_read << " bytes.";
+  RequestComplete(request, bytes_read);
+}
+
+void LogProofFetcher::RequestComplete(net::URLRequest* request,
+                                      int bytes_read) {
+  auto it(inflight_requests_.find(request));
+  DCHECK(it != inflight_requests_.end());
+  if (it->first != request) {
+    NOTREACHED();
+    return;
+  }
+
+  FetchParams* params(it->second);
+  VLOG(1) << "Got " << bytes_read << " bytes.";
+
+  // Extract STH json an parse it
+  std::string json_sth(params->sth_buffer->data(), bytes_read);
+  VLOG(1) << "STH data: " << json_sth;
+
+  FetchParams request_params(*params);
+  // Get rid of the buffer as it really isn't necessary.
+  request_params.sth_buffer = nullptr;
+  scoped_refptr<safe_json_parser::SafeJsonParser> parser =

[Ryan Sleevi, 2015/06/29 11:58:13]

nit: s/parser = /parser(/

+      new safe_json_parser::SafeJsonParser(
+          json_sth,
+          base::Bind(&LogProofFetcher::OnSTHJsonParseSuccess,
+                     weak_factory_.GetWeakPtr(),
+                     request_params),
+          base::Bind(&LogProofFetcher::OnSTHJsonParseError,
+                     weak_factory_.GetWeakPtr(),
+                     request_params));
+  // The parser will call us back via one of the callbacks.
+  parser->Start();
+
+  CleanupRequest(request);
+}
+
+void LogProofFetcher::CleanupRequest(net::URLRequest* request) {
+  VLOG(1) << "Cleaning up request to " << request->original_url();
+  auto it(inflight_requests_.find(request));
+  DCHECK(it != inflight_requests_.end());
+
+  scoped_ptr<FetchParams> params(it->second);
+  // Delete the request, remove from map.
+  scoped_ptr<net::URLRequest> url_request(it->first);
+  // Both pointers will be deleted when exiting the method.
+  VLOG(1) << "Erasing iterator.";
+  inflight_requests_.erase(it);
+}
+
+
+void LogProofFetcher::OnSTHJsonParseSuccess(
+    FetchParams params,
+    scoped_ptr<base::Value> parsed_json) {
+  VLOG(1) << "Successfully parsed STH JSON.";
+  net::ct::SignedTreeHead sth;
+  if (!CTLogResponseParser::FillSignedTreeHead(parsed_json.Pass(), &sth)) {
+    LOG(ERROR) << "Invalid STH.";
+    return;
+  }
+
+  VLOG(1) << "Parsed STH successfully.";
+  params.fetched_callback.Run(params.log_id, sth);
+  VLOG(1) << "Invoked callback.";
+}
+
+void LogProofFetcher::OnSTHJsonParseError(
+    FetchParams params,
+    const std::string& error) {
+  VLOG(1) << "Parsing of STH JSON failed.";
+}
+
+LogProofFetcher::FetchParams::FetchParams(const std::string& id,
+                                          FetchSTHCallback callback)
+    : log_id(id),
+      fetched_callback(callback),
+      sth_buffer(new net::IOBufferWithSize(kMaxSTHSizeInBytes)) {
+}
+
+LogProofFetcher::FetchParams::~FetchParams() {
+}
+
+}  // namespace certificate_transparency