[BR01.1] Support BpfNetMapsReader

A helper class to *read* java BpfMaps. This is designed to
provide direct bpf access in the caller process through
ConnectivityManager APIs.

The change also removes any statical link to
net-utils-device-common-struct from service-connectivity.
This is because net-utils-device-common-struct is already
included in framework-connectivity. Including it again in
service-connectivity would create a r8 build fail by circular
dependency.

Test: atest FrameworksNetTests:android.net.connectivity.com.android.server.BpfNetMapsTest
Test: atest ConnectivityCoverageTests:android.net.connectivity.com.android.net.module.util.StructTest
Test: atest FrameworksNetTests:android.net.connectivity.android.net.BpfNetMapsReaderTest
Bug: 297836825
Change-Id: I7a6d2eb816d0dc7343167bddd672806b199f44fe
diff --git a/service/src/com/android/server/BpfNetMaps.java b/service/src/com/android/server/BpfNetMaps.java
index 6a34a24..671c4ac 100644
--- a/service/src/com/android/server/BpfNetMaps.java
+++ b/service/src/com/android/server/BpfNetMaps.java
@@ -26,6 +26,7 @@
 import static android.net.BpfNetMapsConstants.UID_OWNER_MAP_PATH;
 import static android.net.BpfNetMapsConstants.UID_PERMISSION_MAP_PATH;
 import static android.net.BpfNetMapsConstants.UID_RULES_CONFIGURATION_KEY;
+import static android.net.BpfNetMapsUtils.PRE_T;
 import static android.net.BpfNetMapsUtils.getMatchByFirewallChain;
 import static android.net.BpfNetMapsUtils.matchToString;
 import static android.net.ConnectivityManager.FIREWALL_CHAIN_DOZABLE;
@@ -51,7 +52,9 @@
 
 import android.app.StatsManager;
 import android.content.Context;
+import android.net.BpfNetMapsReader;
 import android.net.INetd;
+import android.net.UidOwnerValue;
 import android.os.Build;
 import android.os.RemoteException;
 import android.os.ServiceSpecificException;
@@ -92,7 +95,6 @@
  * {@hide}
  */
 public class BpfNetMaps {
-    private static final boolean PRE_T = !SdkLevel.isAtLeastT();
     static {
         if (!PRE_T) {
             System.loadLibrary("service-connectivity");
@@ -298,6 +300,7 @@
     }
 
     /** Constructor used after T that doesn't need to use netd anymore. */
+    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
     public BpfNetMaps(final Context context) {
         this(context, null);
 
@@ -420,6 +423,7 @@
      * @throws ServiceSpecificException in case of failure, with an error code indicating the
      *                                  cause of the failure.
      */
+    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
     public void addNaughtyApp(final int uid) {
         throwIfPreT("addNaughtyApp is not available on pre-T devices");
 
@@ -438,6 +442,7 @@
      * @throws ServiceSpecificException in case of failure, with an error code indicating the
      *                                  cause of the failure.
      */
+    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
     public void removeNaughtyApp(final int uid) {
         throwIfPreT("removeNaughtyApp is not available on pre-T devices");
 
@@ -456,6 +461,7 @@
      * @throws ServiceSpecificException in case of failure, with an error code indicating the
      *                                  cause of the failure.
      */
+    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
     public void addNiceApp(final int uid) {
         throwIfPreT("addNiceApp is not available on pre-T devices");
 
@@ -474,6 +480,7 @@
      * @throws ServiceSpecificException in case of failure, with an error code indicating the
      *                                  cause of the failure.
      */
+    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
     public void removeNiceApp(final int uid) {
         throwIfPreT("removeNiceApp is not available on pre-T devices");
 
@@ -494,6 +501,7 @@
      * @throws ServiceSpecificException in case of failure, with an error code indicating the
      *                                  cause of the failure.
      */
+    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
     public void setChildChain(final int childChain, final boolean enable) {
         throwIfPreT("setChildChain is not available on pre-T devices");
 
@@ -523,18 +531,14 @@
      * @throws UnsupportedOperationException if called on pre-T devices.
      * @throws ServiceSpecificException in case of failure, with an error code indicating the
      *                                  cause of the failure.
+     *
+     * @deprecated Use {@link BpfNetMapsReader#isChainEnabled} instead.
      */
+    // TODO: Migrate the callers to use {@link BpfNetMapsReader#isChainEnabled} instead.
+    @Deprecated
+    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
     public boolean isChainEnabled(final int childChain) {
-        throwIfPreT("isChainEnabled is not available on pre-T devices");
-
-        final long match = getMatchByFirewallChain(childChain);
-        try {
-            final U32 config = sConfigurationMap.getValue(UID_RULES_CONFIGURATION_KEY);
-            return (config.val & match) != 0;
-        } catch (ErrnoException e) {
-            throw new ServiceSpecificException(e.errno,
-                    "Unable to get firewall chain status: " + Os.strerror(e.errno));
-        }
+        return BpfNetMapsReader.isChainEnabled(sConfigurationMap, childChain);
     }
 
     private Set<Integer> asSet(final int[] uids) {
@@ -554,6 +558,7 @@
      * @throws UnsupportedOperationException if called on pre-T devices.
      * @throws IllegalArgumentException if {@code chain} is not a valid chain.
      */
+    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
     public void replaceUidChain(final int chain, final int[] uids) {
         throwIfPreT("replaceUidChain is not available on pre-T devices");
 
@@ -638,6 +643,7 @@
      * @throws ServiceSpecificException in case of failure, with an error code indicating the
      *                                  cause of the failure.
      */
+    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
     public void setUidRule(final int childChain, final int uid, final int firewallRule) {
         throwIfPreT("setUidRule is not available on pre-T devices");
 
@@ -667,20 +673,12 @@
      * @throws UnsupportedOperationException if called on pre-T devices.
      * @throws ServiceSpecificException in case of failure, with an error code indicating the
      *                                  cause of the failure.
+     *
+     * @deprecated use {@link BpfNetMapsReader#getUidRule} instead.
      */
+    // TODO: Migrate the callers to use {@link BpfNetMapsReader#getUidRule} instead.
     public int getUidRule(final int childChain, final int uid) {
-        throwIfPreT("isUidChainEnabled is not available on pre-T devices");
-
-        final long match = getMatchByFirewallChain(childChain);
-        final boolean isAllowList = isFirewallAllowList(childChain);
-        try {
-            final UidOwnerValue uidMatch = sUidOwnerMap.getValue(new S32(uid));
-            final boolean isMatchEnabled = uidMatch != null && (uidMatch.rule & match) != 0;
-            return isMatchEnabled == isAllowList ? FIREWALL_RULE_ALLOW : FIREWALL_RULE_DENY;
-        } catch (ErrnoException e) {
-            throw new ServiceSpecificException(e.errno,
-                    "Unable to get uid rule status: " + Os.strerror(e.errno));
-        }
+        return BpfNetMapsReader.getUidRule(sUidOwnerMap, childChain, uid);
     }
 
     private Set<Integer> getUidsMatchEnabled(final int childChain) throws ErrnoException {
@@ -830,6 +828,7 @@
      * @throws ServiceSpecificException in case of failure, with an error code indicating the
      *                                  cause of the failure.
      */
+    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
     public void updateUidLockdownRule(final int uid, final boolean add) {
         throwIfPreT("updateUidLockdownRule is not available on pre-T devices");
 
@@ -852,6 +851,7 @@
      * @throws ServiceSpecificException in case of failure, with an error code indicating the
      *                                  cause of the failure.
      */
+    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
     public void swapActiveStatsMap() {
         throwIfPreT("swapActiveStatsMap is not available on pre-T devices");
 
@@ -927,6 +927,7 @@
     }
 
     /** Register callback for statsd to pull atom. */
+    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
     public void setPullAtomCallback(final Context context) {
         throwIfPreT("setPullAtomCallback is not available on pre-T devices");
 
@@ -1016,6 +1017,7 @@
      * @throws IOException when file descriptor is invalid.
      * @throws ServiceSpecificException when the method is called on an unsupported device.
      */
+    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
     public void dump(final IndentingPrintWriter pw, final FileDescriptor fd, boolean verbose)
             throws IOException, ServiceSpecificException {
         if (PRE_T) {