Create a barebones DNS prober

This will eventually be able to give us some idea whether a DNS configuration
is correct (servers respond) and working (responses are valid and useful).

(Also, I needed to add a constructor to MockDnsClientRule; I modified
HostResolverImplUnittest to use it.)

BUG=156415
TEST=DnsProberUnittest
TBR=jhawkins@chromium.org

Review URL: https://chromiumcodereview.appspot.com/11098062

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@163119 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 77 insertions, 0 deletions

diff --git a/chrome/browser/net/dns_probe_job.h b/chrome/browser/net/dns_probe_job.h
new file mode 100644
index 0000000..b2412e2
--- /dev/null
+++ b/chrome/browser/net/dns_probe_job.h
@@ -0,0 +1,77 @@
+// Copyright (c) 2012 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 CHROME_BROWSER_NET_DNS_PROBE_JOB_H_
+#define CHROME_BROWSER_NET_DNS_PROBE_JOB_H_
+
+#include "base/basictypes.h"
+#include "base/bind.h"
+#include "base/memory/scoped_ptr.h"
+#include "net/base/net_log.h"
+#include "net/dns/dns_transaction.h"
+
+namespace net {
+class DnsClient;
+struct DnsConfig;
+};
+
+namespace chrome_browser_net {
+
+// A job to probe the health of a DNS configuration.
+class DnsProbeJob {
+ public:
+  enum Result {
+    DNS_UNKNOWN,
+    DNS_WORKING,  // Server responds with correct answers.
+    // TODO(ttuttle): Do we want an "unreliable" result, for e.g. servers that
+    // lie about NXDOMAIN?
+    DNS_BROKEN,  // Server responds with errors.
+    DNS_UNREACHABLE,  // Server doesn't respond (or never got our packets)
+  };
+  typedef base::Callback<void(DnsProbeJob* job, Result result)> CallbackType;
+
+  // Creates and starts a probe job.
+  //
+  // |dns_client| should be a DnsClient with the DnsConfig alreay set.
+  // |callback| will be called when the probe finishes, which may happen
+  // before the constructor returns (for example, if we can't create the DNS
+  // transactions).
+  DnsProbeJob(scoped_ptr<net::DnsClient> dns_client,
+              const CallbackType& callback,
+              net::NetLog* net_log);
+  ~DnsProbeJob();
+
+ private:
+  enum QueryStatus {
+    QUERY_UNKNOWN,
+    QUERY_CORRECT,
+    QUERY_INCORRECT,
+    QUERY_ERROR,
+    QUERY_RUNNING,
+  };
+
+  void MaybeFinishProbe();
+  scoped_ptr<net::DnsTransaction> CreateTransaction(
+      const std::string& hostname);
+  void StartTransaction(net::DnsTransaction* transaction);
+  void OnTransactionComplete(net::DnsTransaction* transaction,
+                             int net_error,
+                             const net::DnsResponse* response);
+  void RunCallback(Result result);
+
+  net::BoundNetLog bound_net_log_;
+  scoped_ptr<net::DnsClient> dns_client_;
+  const CallbackType callback_;
+  bool probe_running_;
+  scoped_ptr<net::DnsTransaction> good_transaction_;
+  scoped_ptr<net::DnsTransaction> bad_transaction_;
+  QueryStatus good_status_;
+  QueryStatus bad_status_;
+
+  DISALLOW_COPY_AND_ASSIGN(DnsProbeJob);
+};
+
+}  // namespace chrome_browser_net
+
+#endif  // CHROME_BROWSER_NET_DNS_PROBE_JOB_H_