Add tether offload traffic to interface stats as well.

Currently, we only count add tethering traffic to per-UID
stats, but not to total data usage (i.e., dev and XT stats). This
is correct for software tethering, because all software forwarded
packets are already included in interface counters, but it is
incorrect for hardware offload, because such packets do not
increment interface counters.

To fix this:
1. Add an argument to ITetheringStatsProvider#getTetherStats to
   indicate whether per-UID stats are requested. For clarity,
   define integer constants STATS_PER_IFACE and STATS_PER_UID
   to represent these operations.
2. Make NetdTetheringStatsProvider return stats only if per-UID
   stats are requested. (Otherwise tethering traffic would be
   double-counted).
3. Make OffloadController's stats provider return the same
   stats regardless of whether per-UID stats were requested or
   not.
4. Make NetworkStatsService add non-per-UID tethering stats to
   the dev and XT snapshots. The per-UID snapshots were already
   correctly adding in per-UID stats.

Bug: 29337859
Bug: 32163131
Test: runtest frameworks-net
Test: runtest frameworks-telephony
Change-Id: I7a4d04ab47694d754874136179f8edad71099638

tests/net/java/com/android/server/net/NetworkStatsServiceTest.java

@@ -31,6 +31,8 @@ import static android.net.NetworkStats.ROAMING_YES;
 import static android.net.NetworkStats.SET_ALL;
 import static android.net.NetworkStats.SET_DEFAULT;
 import static android.net.NetworkStats.SET_FOREGROUND;
+import static android.net.NetworkStats.STATS_PER_IFACE;
+import static android.net.NetworkStats.STATS_PER_UID;
 import static android.net.NetworkStats.TAG_NONE;
 import static android.net.NetworkStats.UID_ALL;
 import static android.net.NetworkStatsHistory.FIELD_ALL;
@@ -823,17 +825,24 @@ public class NetworkStatsServiceTest {
         incrementCurrentTime(HOUR_IN_MILLIS);
         expectCurrentTime();
         expectDefaultSettings();
-        expectNetworkStatsSummary(new NetworkStats(getElapsedRealtime(), 1)
-                .addIfaceValues(TEST_IFACE, 2048L, 16L, 512L, 4L));
 
+        // Traffic seen by kernel counters (includes software tethering).
+        final NetworkStats ifaceStats = new NetworkStats(getElapsedRealtime(), 1)
+                .addIfaceValues(TEST_IFACE, 1536L, 12L, 384L, 3L);
+        // Hardware tethering traffic, not seen by kernel counters.
+        final NetworkStats tetherStatsHardware = new NetworkStats(getElapsedRealtime(), 1)
+                .addIfaceValues(TEST_IFACE, 512L, 4L, 128L, 1L);
+
+        // Traffic for UID_RED.
         final NetworkStats uidStats = new NetworkStats(getElapsedRealtime(), 1)
                 .addValues(TEST_IFACE, UID_RED, SET_DEFAULT, TAG_NONE, 128L, 2L, 128L, 2L, 0L);
-        final String[] tetherIfacePairs = new String[] { TEST_IFACE, "wlan0" };
+        // All tethering traffic, both hardware and software.
         final NetworkStats tetherStats = new NetworkStats(getElapsedRealtime(), 1)
                 .addValues(TEST_IFACE, UID_TETHERING, SET_DEFAULT, TAG_NONE, 1920L, 14L, 384L, 2L,
                         0L);
 
-        expectNetworkStatsUidDetail(uidStats, tetherIfacePairs, tetherStats);
+        expectNetworkStatsSummary(ifaceStats, tetherStatsHardware);
+        expectNetworkStatsUidDetail(uidStats, tetherStats);
         forcePollAndWaitForIdle();
 
         // verify service recorded history
@@ -1013,10 +1022,16 @@ public class NetworkStatsServiceTest {
     }
 
     private void expectNetworkStatsSummary(NetworkStats summary) throws Exception {
+        expectNetworkStatsSummary(summary, new NetworkStats(0L, 0));
+    }
+
+    private void expectNetworkStatsSummary(NetworkStats summary, NetworkStats tetherStats)
+            throws Exception {
         when(mConnManager.getAllVpnInfo()).thenReturn(new VpnInfo[0]);
 
-        expectNetworkStatsSummaryDev(summary);
+        expectNetworkStatsTethering(STATS_PER_IFACE, tetherStats);
-        expectNetworkStatsSummaryXt(summary);
+        expectNetworkStatsSummaryDev(summary.clone());
+        expectNetworkStatsSummaryXt(summary.clone());
     }
 
     private void expectNetworkStatsSummaryDev(NetworkStats summary) throws Exception {
@@ -1027,17 +1042,21 @@ public class NetworkStatsServiceTest {
         when(mNetManager.getNetworkStatsSummaryXt()).thenReturn(summary);
     }
 
-    private void expectNetworkStatsUidDetail(NetworkStats detail) throws Exception {
+    private void expectNetworkStatsTethering(int how, NetworkStats stats)
-        expectNetworkStatsUidDetail(detail, new String[0], new NetworkStats(0L, 0));
+            throws Exception {
+        when(mNetManager.getNetworkStatsTethering(how)).thenReturn(stats);
     }
 
-    private void expectNetworkStatsUidDetail(
+    private void expectNetworkStatsUidDetail(NetworkStats detail) throws Exception {
-            NetworkStats detail, String[] tetherIfacePairs, NetworkStats tetherStats)
+        expectNetworkStatsUidDetail(detail, new NetworkStats(0L, 0));
+    }
+
+    private void expectNetworkStatsUidDetail(NetworkStats detail, NetworkStats tetherStats)
             throws Exception {
         when(mNetManager.getNetworkStatsUidDetail(UID_ALL)).thenReturn(detail);
 
         // also include tethering details, since they are folded into UID
-        when(mNetManager.getNetworkStatsTethering()).thenReturn(tetherStats);
+        when(mNetManager.getNetworkStatsTethering(STATS_PER_UID)).thenReturn(tetherStats);
     }
 
     private void expectDefaultSettings() throws Exception {