Display DNS probe results.

chrome/browser/net/dns_probe_runner.cc

+// Copyright (c) 2013 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 "chrome/browser/net/dns_probe_runner.h"
+
+#include "base/bind.h"
+#include "content/public/browser/browser_thread.h"
+#include "net/base/address_list.h"
+#include "net/base/ip_endpoint.h"
+#include "net/base/net_errors.h"
+#include "net/base/net_log.h"
+#include "net/base/net_util.h"
+#include "net/base/network_change_notifier.h"
+#include "net/dns/dns_client.h"
+#include "net/dns/dns_protocol.h"
+#include "net/dns/dns_response.h"
+#include "net/dns/dns_transaction.h"
+
+using base::TimeDelta;
+using content::BrowserThread;
+using net::AddressList;
+using net::BoundNetLog;
+using net::DnsClient;
+using net::DnsResponse;
+using net::DnsTransaction;
+using net::IPAddressNumber;
+using net::IPEndPoint;
+using net::NetLog;
+using net::NetworkChangeNotifier;
+using net::ParseIPLiteralToNumber;
+
+namespace chrome_browser_net {
+
+namespace {
+
+const char* kKnownGoodHostname = "google.com";
+
+DnsProbeRunner::Result EvaluateResponse(
+    int net_error,
+    const DnsResponse* response) {
+  switch (net_error) {
+    case net::OK:
+      break;
+
+    // ERR_NAME_NOT_RESOLVED maps to NXDOMAIN, which means the server is working
+    // but gave us a wrong answer.
+    case net::ERR_NAME_NOT_RESOLVED:
+      return DnsProbeRunner::INCORRECT;
+
+    // These results mean we heard *something* from the DNS server, but it was
+    // unsuccessful (SERVFAIL) or malformed.
+    case net::ERR_DNS_MALFORMED_RESPONSE:
+    case net::ERR_DNS_SERVER_REQUIRES_TCP:  // Shouldn't happen; DnsTransaction
+                                            // will retry with TCP.
+    case net::ERR_DNS_SERVER_FAILED:
+    case net::ERR_DNS_SORT_ERROR:  // Can only happen if the server responds.
+      return DnsProbeRunner::FAILING;
+
+    // Any other error means we never reached the DNS server in the first place.
+    case net::ERR_DNS_TIMED_OUT:
+    default:
+      // Something else happened, probably at a network level.
+      return DnsProbeRunner::UNREACHABLE;
+  }
+
+  AddressList addr_list;
+  TimeDelta ttl;
+  DnsResponse::Result result = response->ParseToAddressList(&addr_list, &ttl);
+
+  if (result != DnsResponse::DNS_PARSE_OK) {
+    return DnsProbeRunner::FAILING;
+  }
+
+  if (addr_list.empty()) {
+    return DnsProbeRunner::INCORRECT;
+  }
+
+  return DnsProbeRunner::CORRECT;
+}
+
+}  // namespace
+
+DnsProbeRunner::DnsProbeRunner() : weak_factory_(this), result_(UNKNOWN) {}
+
+DnsProbeRunner::~DnsProbeRunner() {}
+
+void DnsProbeRunner::RunProbe(const base::Closure& callback) {
+  DCHECK(!callback.is_null());
+  DCHECK(client_.get());
+  DCHECK(callback_.is_null());
+  DCHECK(!transaction_.get());
+
+  callback_ = callback;
+  transaction_ = client_->GetTransactionFactory()->CreateTransaction(
+      kKnownGoodHostname,
+      net::dns_protocol::kTypeA,
+      base::Bind(&DnsProbeRunner::OnTransactionComplete,
+                 weak_factory_.GetWeakPtr()),
+      BoundNetLog());
+
+  int rv = transaction_->Start();
+  if (rv != net::ERR_IO_PENDING)
+    OnTransactionComplete(transaction_.get(), rv, NULL);
+}
+
+void DnsProbeRunner::SetClient(scoped_ptr<net::DnsClient> client) {
+  client_ = client.Pass();
+}
+
+bool DnsProbeRunner::IsRunning() const {
+  return !callback_.is_null();
+}
+
+void DnsProbeRunner::OnTransactionComplete(
+    DnsTransaction* transaction,
+    int net_error,
+    const DnsResponse* response) {
+  DCHECK(!callback_.is_null());
+  DCHECK(transaction_.get());
+  DCHECK_EQ(transaction_.get(), transaction);
+
+  result_ = EvaluateResponse(net_error, response);
+  transaction_.reset();
+
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&DnsProbeRunner::CallCallback,
+                 weak_factory_.GetWeakPtr()));
+}
+
+void DnsProbeRunner::CallCallback() {
+  DCHECK(!callback_.is_null());
+  DCHECK(!transaction_.get());
+
+  // Clear callback in case it starts a new probe immediately.
+  const base::Closure callback = callback_;
+  callback_.Reset();
+  callback.Run();
+}
+
+}  // namespace chrome_browser_net