Keep debug information in NetworkStats files

Create two special SETs.

SET_DBG_VPN_IN is used by individual applications to know
how much traffic of the NetworkIdentity was actually moved
from a VPN app.
SET_DBG_VPN_OUT is used by the VPN app to know how much
traffic of the NetworkIdentity was deducted.

A debug application can restore the raw stats by these
entries.
  raw_traffic = recorded_entry (TAG_NONE, SET_ALL)
              + recorded_entry (TAG_NONE, SET_DBF_VPN_OUT)
              - recorded_entry (TAG_NONE, SET_DBF_VPN_IN)

The two debug SETs are not returned by
NetworkStatsService.openSession(). These debug entries are
retrieved by NetworkStatsCollection.dump().

Bug: 19536273
Change-Id: I03ef9f7667f5f2f48cbe3f6b11447fe7ead8ad3b

core/java/android/net/NetworkStats.java

@@ -50,12 +50,19 @@ public class NetworkStats implements Parcelable {
     public static final int UID_ALL = -1;
     /** {@link #tag} value matching any tag. */
     public static final int TAG_ALL = -1;
-    /** {@link #set} value when all sets combined. */
+    /** {@link #set} value when all sets combined, not including debug sets. */
     public static final int SET_ALL = -1;
     /** {@link #set} value where background data is accounted. */
     public static final int SET_DEFAULT = 0;
     /** {@link #set} value where foreground data is accounted. */
     public static final int SET_FOREGROUND = 1;
+    /** All {@link #set} value greater than SET_DEBUG_START are debug {@link #set} values. */
+    public static final int SET_DEBUG_START = 1000;
+    /** Debug {@link #set} value when the VPN stats are moved in. */
+    public static final int SET_DBG_VPN_IN = 1001;
+    /** Debug {@link #set} value when the VPN stats are moved out of a vpn UID. */
+    public static final int SET_DBG_VPN_OUT = 1002;
+
     /** {@link #tag} value for total data across all tags. */
     public static final int TAG_NONE = 0;
 
@@ -729,6 +736,10 @@ public class NetworkStats implements Parcelable {
                 return "DEFAULT";
             case SET_FOREGROUND:
                 return "FOREGROUND";
+            case SET_DBG_VPN_IN:
+                return "DBG_VPN_IN";
+            case SET_DBG_VPN_OUT:
+                return "DBG_VPN_OUT";
             default:
                 return "UNKNOWN";
         }
@@ -745,11 +756,26 @@ public class NetworkStats implements Parcelable {
                 return "def";
             case SET_FOREGROUND:
                 return "fg";
+            case SET_DBG_VPN_IN:
+                return "vpnin";
+            case SET_DBG_VPN_OUT:
+                return "vpnout";
             default:
                 return "unk";
         }
     }
 
+    /**
+     * @return true if the querySet matches the dataSet.
+     */
+    public static boolean setMatches(int querySet, int dataSet) {
+        if (querySet == dataSet) {
+            return true;
+        }
+        // SET_ALL matches all non-debugging sets.
+        return querySet == SET_ALL && dataSet < SET_DEBUG_START;
+    }
+
     /**
      * Return text description of {@link #tag} value.
      */
@@ -843,6 +869,9 @@ public class NetworkStats implements Parcelable {
             if (recycle.uid == UID_ALL) {
                 throw new IllegalStateException(
                         "Cannot adjust VPN accounting on an iface aggregated NetworkStats.");
+            } if (recycle.set == SET_DBG_VPN_IN || recycle.set == SET_DBG_VPN_OUT) {
+                throw new IllegalStateException(
+                        "Cannot adjust VPN accounting on a NetworkStats containing SET_DBG_VPN_*");
             }
 
             if (recycle.uid == tunUid && recycle.tag == TAG_NONE
@@ -906,6 +935,9 @@ public class NetworkStats implements Parcelable {
                 combineValues(tmpEntry);
                 if (tag[i] == TAG_NONE) {
                     moved.add(tmpEntry);
+                    // Add debug info
+                    tmpEntry.set = SET_DBG_VPN_IN;
+                    combineValues(tmpEntry);
                 }
             }
         }
@@ -913,6 +945,13 @@ public class NetworkStats implements Parcelable {
     }
 
     private void deductTrafficFromVpnApp(int tunUid, String underlyingIface, Entry moved) {
+        // Add debug info
+        moved.uid = tunUid;
+        moved.set = SET_DBG_VPN_OUT;
+        moved.tag = TAG_NONE;
+        moved.iface = underlyingIface;
+        combineValues(moved);
+
         // Caveat: if the vpn software uses tag, the total tagged traffic may be greater than
         // the TAG_NONE traffic.
         int idxVpnBackground = findIndex(underlyingIface, tunUid, SET_DEFAULT, TAG_NONE);

services/core/java/com/android/server/net/NetworkStatsCollection.java

@@ -182,8 +182,7 @@ public class NetworkStatsCollection implements FileRotator.Reader {
 
         for (int i = 0; i < mStats.size(); i++) {
             final Key key = mStats.keyAt(i);
-            final boolean setMatches = set == SET_ALL || key.set == set;
+            if (key.uid == uid && NetworkStats.setMatches(set, key.set) && key.tag == tag
-            if (key.uid == uid && setMatches && key.tag == tag
                     && templateMatches(template, key.ident)) {
                 final NetworkStatsHistory value = mStats.valueAt(i);
                 combined.recordHistory(value, start, end);
@@ -209,7 +208,8 @@ public class NetworkStatsCollection implements FileRotator.Reader {
         final int callerUid = Binder.getCallingUid();
         for (int i = 0; i < mStats.size(); i++) {
             final Key key = mStats.keyAt(i);
-            if (templateMatches(template, key.ident) && isAccessibleToUser(key.uid, callerUid)) {
+            if (templateMatches(template, key.ident) && isAccessibleToUser(key.uid, callerUid)
+                    && key.set < NetworkStats.SET_DEBUG_START) {
                 final NetworkStatsHistory value = mStats.valueAt(i);
                 historyEntry = value.getValues(start, end, now, historyEntry);
 
@@ -542,6 +542,7 @@ public class NetworkStatsCollection implements FileRotator.Reader {
             final NetworkStatsHistory value = mStats.valueAt(i);
 
             if (!templateMatches(groupTemplate, key.ident)) continue;
+            if (key.set >= NetworkStats.SET_DEBUG_START) continue;
 
             final Key groupKey = new Key(null, key.uid, key.set, key.tag);
             NetworkStatsHistory groupHistory = grouped.get(groupKey);