DO NOT MERGE NetworkMonitor: send one DNS probe per web probe

am: eb5e9aa2ce

Change-Id: I2e3d9794e56d434f838ead9f12ee4edc74a3d6f2

services/core/java/com/android/server/connectivity/NetworkMonitor.java

@@ -707,48 +707,13 @@ public class NetworkMonitor extends StateMachine {
 
         long startTime = SystemClock.elapsedRealtime();
 
-        // Pre-resolve the captive portal server host so we can log it.
+        final CaptivePortalProbeResult result;
-        // Only do this if HttpURLConnection is about to, to avoid any potentially
-        // unnecessary resolution.
-        String hostToResolve = null;
         if (pacUrl != null) {
-            hostToResolve = pacUrl.getHost();
+            result = sendDnsAndHttpProbes(null, pacUrl, ValidationProbeEvent.PROBE_PAC);
-        } else if (proxyInfo != null) {
-            hostToResolve = proxyInfo.getHost();
-        } else {
-            hostToResolve = httpUrl.getHost();
-        }
-
-        if (!TextUtils.isEmpty(hostToResolve)) {
-            String probeName = ValidationProbeEvent.getProbeName(ValidationProbeEvent.PROBE_DNS);
-            final Stopwatch dnsTimer = new Stopwatch().start();
-            int dnsResult;
-            long dnsLatency;
-            try {
-                InetAddress[] addresses = mNetworkAgentInfo.network.getAllByName(hostToResolve);
-                dnsResult = ValidationProbeEvent.DNS_SUCCESS;
-                dnsLatency = dnsTimer.stop();
-                final StringBuffer connectInfo = new StringBuffer(", " + hostToResolve + "=");
-                for (InetAddress address : addresses) {
-                    connectInfo.append(address.getHostAddress());
-                    if (address != addresses[addresses.length-1]) connectInfo.append(",");
-                }
-                validationLog(probeName + " OK " + dnsLatency + "ms" + connectInfo);
-            } catch (UnknownHostException e) {
-                dnsResult = ValidationProbeEvent.DNS_FAILURE;
-                dnsLatency = dnsTimer.stop();
-                validationLog(probeName + " FAIL " + dnsLatency + "ms, " + hostToResolve);
-            }
-            logValidationProbe(dnsLatency, ValidationProbeEvent.PROBE_DNS, dnsResult);
-        }
-
-        CaptivePortalProbeResult result;
-        if (pacUrl != null) {
-            result = sendHttpProbe(pacUrl, ValidationProbeEvent.PROBE_PAC);
         } else if (mUseHttps) {
-            result = sendParallelHttpProbes(httpsUrl, httpUrl, fallbackUrl);
+            result = sendParallelHttpProbes(proxyInfo, httpsUrl, httpUrl, fallbackUrl);
         } else {
-            result = sendHttpProbe(httpUrl, ValidationProbeEvent.PROBE_HTTP);
+            result = sendDnsAndHttpProbes(proxyInfo, httpUrl, ValidationProbeEvent.PROBE_HTTP);
         }
 
         long endTime = SystemClock.elapsedRealtime();
@@ -761,8 +726,50 @@ public class NetworkMonitor extends StateMachine {
     }
 
     /**
-     * Do a URL fetch on a known server to see if we get the data we expect.
+     * Do a DNS resolution and URL fetch on a known web server to see if we get the data we expect.
-     * Returns HTTP response code.
+     * @return a CaptivePortalProbeResult inferred from the HTTP response.
+     */
+    private CaptivePortalProbeResult sendDnsAndHttpProbes(ProxyInfo proxy, URL url, int probeType) {
+        // Pre-resolve the captive portal server host so we can log it.
+        // Only do this if HttpURLConnection is about to, to avoid any potentially
+        // unnecessary resolution.
+        final String host = (proxy != null) ? proxy.getHost() : url.getHost();
+        sendDnsProbe(host);
+        return sendHttpProbe(url, probeType);
+    }
+
+    /** Do a DNS resolution of the given server. */
+    private void sendDnsProbe(String host) {
+        if (TextUtils.isEmpty(host)) {
+            return;
+        }
+
+        final String name = ValidationProbeEvent.getProbeName(ValidationProbeEvent.PROBE_DNS);
+        final Stopwatch watch = new Stopwatch().start();
+        int result;
+        String connectInfo;
+        try {
+            InetAddress[] addresses = mNetworkAgentInfo.network.getAllByName(host);
+            result = ValidationProbeEvent.DNS_SUCCESS;
+            StringBuffer buffer = new StringBuffer(host).append("=");
+            for (InetAddress address : addresses) {
+                buffer.append(address.getHostAddress());
+                if (address != addresses[addresses.length-1]) buffer.append(",");
+            }
+            connectInfo = buffer.toString();
+        } catch (UnknownHostException e) {
+            result = ValidationProbeEvent.DNS_FAILURE;
+            connectInfo = host;
+        }
+        final long latency = watch.stop();
+        String resultString = (ValidationProbeEvent.DNS_SUCCESS == result) ? "OK" : "FAIL";
+        validationLog(String.format("%s %s %dms, %s", name, resultString, latency, connectInfo));
+        logValidationProbe(latency, ValidationProbeEvent.PROBE_DNS, result);
+    }
+
+    /**
+     * Do a URL fetch on a known web server to see if we get the data we expect.
+     * @return a CaptivePortalProbeResult inferred from the HTTP response.
      */
     @VisibleForTesting
     protected CaptivePortalProbeResult sendHttpProbe(URL url, int probeType) {
@@ -829,7 +836,7 @@ public class NetworkMonitor extends StateMachine {
     }
 
     private CaptivePortalProbeResult sendParallelHttpProbes(
-            URL httpsUrl, URL httpUrl, URL fallbackUrl) {
+            ProxyInfo proxy, URL httpsUrl, URL httpUrl, URL fallbackUrl) {
         // Number of probes to wait for. If a probe completes with a conclusive answer
         // it shortcuts the latch immediately by forcing the count to 0.
         final CountDownLatch latch = new CountDownLatch(2);
@@ -849,9 +856,10 @@ public class NetworkMonitor extends StateMachine {
             @Override
             public void run() {
                 if (mIsHttps) {
-                    mResult = sendHttpProbe(httpsUrl, ValidationProbeEvent.PROBE_HTTPS);
+                    mResult =
+                            sendDnsAndHttpProbes(proxy, httpsUrl, ValidationProbeEvent.PROBE_HTTPS);
                 } else {
-                    mResult = sendHttpProbe(httpUrl, ValidationProbeEvent.PROBE_HTTP);
+                    mResult = sendDnsAndHttpProbes(proxy, httpUrl, ValidationProbeEvent.PROBE_HTTP);
                 }
                 if ((mIsHttps && mResult.isSuccessful()) || (!mIsHttps && mResult.isPortal())) {
                     // Stop waiting immediately if https succeeds or if http finds a portal.