shill: Refactor DNS server testing code
Implement the DNSServerTester class for performing DNS server test
in shill. This class will be used for performing DNS test for fallback
DNS servers and configured DNS servers.
BUG=chromium:377056
TEST=unit tests, manual test
Manual Test:
1. Connect a chrome device to "GoogleGuest", set the DNS servers
for the network to an unknown IP address "192.168.1.1".
2. Browse to "chrome://histograms", and verify there is a histogram
for "Network.Shill.Wifi.FallbackDNSTestResult".
Change-Id: Iaf9c0322501ae273f4635f1d865d41f8f51b114f
Reviewed-on: https://chromium-review.googlesource.com/207136
Reviewed-by: Paul Stewart <pstew@chromium.org>
Commit-Queue: Peter Qiu <zqiu@chromium.org>
Tested-by: Peter Qiu <zqiu@chromium.org>
diff --git a/dns_server_tester.h b/dns_server_tester.h
new file mode 100644
index 0000000..64f4a36
--- /dev/null
+++ b/dns_server_tester.h
@@ -0,0 +1,93 @@
+// Copyright (c) 2014 The Chromium OS 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 SHILL_DNS_SERVER_TESTER_H_
+#define SHILL_DNS_SERVER_TESTER_H_
+
+#include <string>
+#include <vector>
+
+#include <base/callback.h>
+#include <base/cancelable_callback.h>
+#include <base/memory/ref_counted.h>
+#include <base/memory/scoped_ptr.h>
+#include <base/memory/weak_ptr.h>
+#include <gtest/gtest_prod.h> // for FRIEND_TEST
+
+#include "shill/ip_address.h"
+#include "shill/refptr_types.h"
+
+namespace shill {
+
+class DNSClient;
+class Error;
+class EventDispatcher;
+
+// The DNSServerTester class implements the DNS health check
+// facility in shill, which is responsible for checking to see
+// if the given DNS servers are working or not.
+//
+// The tester support two modes of operation, continuous and
+// non-continuous mode. With continuous mode (retry_until_success_ flag is set),
+// the tester will continue to perform DNS test until the DNS test succeed or
+// the DNS client failed to start. The callback is only invoke when the test
+// succeed or we failed to start the DNS client. With non-continuous mode,
+// only one DNS test is performed. And the callback is invoked regardless of
+// the result of the test.
+class DNSServerTester {
+ public:
+ enum Status {
+ kStatusFailure,
+ kStatusSuccess,
+ };
+
+ DNSServerTester(ConnectionRefPtr connection,
+ EventDispatcher *dispatcher,
+ const std::vector<std::string> &dns_servers,
+ const bool retry_until_success,
+ const base::Callback<void(const Status)> &callback);
+ virtual ~DNSServerTester();
+
+ // Start the test.
+ virtual void Start();
+
+ // End the current DNS test process if one exist, and do not call
+ // the callback.
+ virtual void Stop();
+
+ private:
+ friend class DNSServerTesterTest;
+ FRIEND_TEST(DNSServerTesterTest, StartAttempt);
+ FRIEND_TEST(DNSServerTesterTest, StartAttemptTask);
+ FRIEND_TEST(DNSServerTesterTest, AttemptCompleted);
+ FRIEND_TEST(DNSServerTesterTest, StopAttempt);
+
+ static const char kDNSTestHostname[];
+ static const int kDNSTestRetryIntervalMilliseconds;
+ static const int kDNSTimeoutMilliseconds;
+
+ void StartAttempt(int delay_ms);
+ void StartAttemptTask();
+ void StopAttempt();
+ void CompleteAttempt(Status status);
+ void DNSClientCallback(const Error &error, const IPAddress &ip);
+
+ ConnectionRefPtr connection_;
+ EventDispatcher *dispatcher_;
+ // Flag indicating to continuously probing the DNS servers until it succeed.
+ // The callback is only invoke when the test succeed or test failed to start.
+ bool retry_until_success_;
+ base::WeakPtrFactory<DNSServerTester> weak_ptr_factory_;
+ base::CancelableClosure start_attempt_;
+ base::Callback<void(const Status)> dns_result_callback_;
+ base::Callback<void(const Error &, const IPAddress &)>
+ dns_client_callback_;
+ scoped_ptr<DNSClient> dns_test_client_;
+
+ DISALLOW_COPY_AND_ASSIGN(DNSServerTester);
+};
+
+} // namespace shill
+
+#endif // SHILL_DNS_SERVER_TESTER_H_