Add dump for Vpn

Adding additional logging and dump information to help VPN debug.

Sample dump result(adb shell dumpsys vpn_management)

VPNs:
  0: com.vpn.test
    Active package name: com.vpn.test
    Active vpn type: 2
    NetworkCapabilities: [ Transports: VPN Capabilities: NOT_METERED&INTERNET&NOT_RESTRICTED&TRUSTED&NOT_VCN_MANAGED TransportInfo: <VpnTransportInfo{type=2, sessionId=null}> Uids: <{0-99999}> OwnerUid: 10106 AdminUids: [10106] UnderlyingNetworks: [107]]
    Token: 8876c2c4-df5f-46b8-82c7-8f124178254a
    MOBIKE enabled
    mUnderlyNetworkChanges (most recent first):
      2022-10-31T17:42:31.039068 - Switch to 107
      2022-10-31T17:42:29.510574 - Agent connect. Switch to 105
      2022-10-31T17:41:57.590691 - Agent connect. Switch to 103
      2022-10-31T17:41:31.269923 - Switch to 103
      2022-10-31T17:41:20.145050 - Switch to 102
      2022-10-31T17:41:14.480618 - Agent connect. Switch to 100
    mVpnManagerEvent (most recent first):
      2022-10-31T17:42:11.641201 - Event class=ERROR_CLASS_RECOVERABLE, err=ERROR_CODE_NETWORK_LOST for com.vpn.test on session 8876c2c4-df5f-46b8-82c7-8f124178254a
      2022-10-31T17:41:34.921219 - com.vpn.test stopped

Test: atest FrameworksNetTests
Test: adb shell dumpsys vpn_management
Bug: 238696406
Change-Id: I05b66ddb4a2b7a73707db39c6b89bf497aed1266

services/core/java/com/android/server/VpnManagerService.java

@@ -186,6 +186,10 @@ public class VpnManagerService extends IVpnManager.Stub {
         synchronized (mVpns) {
             for (int i = 0; i < mVpns.size(); i++) {
                 pw.println(mVpns.keyAt(i) + ": " + mVpns.valueAt(i).getPackage());
+                pw.increaseIndent();
+                mVpns.valueAt(i).dump(pw);
+                pw.decreaseIndent();
+                pw.println();
             }
             pw.decreaseIndent();
         }

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

@@ -124,6 +124,8 @@ import android.system.keystore2.KeyDescriptor;
 import android.system.keystore2.KeyPermission;
 import android.text.TextUtils;
 import android.util.ArraySet;
+import android.util.IndentingPrintWriter;
+import android.util.LocalLog;
 import android.util.Log;
 import android.util.Range;
 
@@ -289,6 +291,10 @@ public class Vpn {
         return mVpnProfileStore;
     }
 
+    private static final int MAX_EVENTS_LOGS = 20;
+    private final LocalLog mUnderlyNetworkChanges = new LocalLog(MAX_EVENTS_LOGS);
+    private final LocalLog mVpnManagerEvents = new LocalLog(MAX_EVENTS_LOGS);
+
     /**
      * Whether to keep the connection active after rebooting, or upgrading or reinstalling. This
      * only applies to {@link VpnService} connections.
@@ -816,6 +822,9 @@ public class Vpn {
             int errorCode, @NonNull final String packageName, @Nullable final String sessionKey,
             @NonNull final VpnProfileState profileState, @Nullable final Network underlyingNetwork,
             @Nullable final NetworkCapabilities nc, @Nullable final LinkProperties lp) {
+        mVpnManagerEvents.log("Event class=" + getVpnManagerEventClassName(errorClass)
+                + ", err=" + getVpnManagerEventErrorName(errorCode) + " for " + packageName
+                + " on session " + sessionKey);
         final Intent intent = buildVpnManagerEventIntent(category, errorClass, errorCode,
                 packageName, sessionKey, profileState, underlyingNetwork, nc, lp);
         return sendEventToVpnManagerApp(intent, packageName);
@@ -1539,6 +1548,7 @@ public class Vpn {
                 ? Arrays.asList(mConfig.underlyingNetworks) : null);
 
         mNetworkCapabilities = capsBuilder.build();
+        logUnderlyNetworkChanges(mNetworkCapabilities.getUnderlyingNetworks());
         mNetworkAgent = mDeps.newNetworkAgent(mContext, mLooper, NETWORKTYPE /* logtag */,
                 mNetworkCapabilities, lp,
                 new NetworkScore.Builder().setLegacyInt(VPN_DEFAULT_SCORE).build(),
@@ -1566,6 +1576,11 @@ public class Vpn {
         }
     }
 
+    private void logUnderlyNetworkChanges(List<Network> networks) {
+        mUnderlyNetworkChanges.log("Switch to "
+                + ((networks != null) ? TextUtils.join(", ", networks) : "null"));
+    }
+
     private void agentDisconnect(NetworkAgent networkAgent) {
         if (networkAgent != null) {
             networkAgent.unregister();
@@ -4231,6 +4246,7 @@ public class Vpn {
         // TODO(b/230548427): Remove SDK check once VPN related stuff are decoupled from
         //  ConnectivityServiceTest.
         if (SdkLevel.isAtLeastT()) {
+            mVpnManagerEvents.log(packageName + " stopped");
             sendEventToVpnManagerApp(intent, packageName);
         }
     }
@@ -4398,8 +4414,10 @@ public class Vpn {
     /** Proxy to allow different testing setups */
     // TODO: b/240492694 Remove VpnNetworkAgentWrapper and this method when
     // NetworkAgent#setUnderlyingNetworks can be un-finalized.
-    private static void doSetUnderlyingNetworks(
+    private void doSetUnderlyingNetworks(
             @NonNull NetworkAgent agent, @NonNull List<Network> networks) {
+        logUnderlyNetworkChanges(networks);
+
         if (agent instanceof VpnNetworkAgentWrapper) {
             ((VpnNetworkAgentWrapper) agent).doSetUnderlyingNetworks(networks);
         } else {
@@ -4518,4 +4536,57 @@ public class Vpn {
     static Range<Integer> createUidRangeForUser(int userId) {
         return new Range<Integer>(userId * PER_USER_RANGE, (userId + 1) * PER_USER_RANGE - 1);
     }
+
+    private String getVpnManagerEventClassName(int code) {
+        switch (code) {
+            case VpnManager.ERROR_CLASS_NOT_RECOVERABLE:
+                return "ERROR_CLASS_NOT_RECOVERABLE";
+            case VpnManager.ERROR_CLASS_RECOVERABLE:
+                return "ERROR_CLASS_RECOVERABLE";
+            default:
+                return "UNKNOWN_CLASS";
+        }
+    }
+
+    private String getVpnManagerEventErrorName(int code) {
+        switch (code) {
+            case VpnManager.ERROR_CODE_NETWORK_UNKNOWN_HOST:
+                return "ERROR_CODE_NETWORK_UNKNOWN_HOST";
+            case VpnManager.ERROR_CODE_NETWORK_PROTOCOL_TIMEOUT:
+                return "ERROR_CODE_NETWORK_PROTOCOL_TIMEOUT";
+            case VpnManager.ERROR_CODE_NETWORK_IO:
+                return "ERROR_CODE_NETWORK_IO";
+            case VpnManager.ERROR_CODE_NETWORK_LOST:
+                return "ERROR_CODE_NETWORK_LOST";
+            default:
+                return "UNKNOWN_ERROR";
+        }
+    }
+
+    /** Dumps VPN state. */
+    public void dump(IndentingPrintWriter pw) {
+        synchronized (Vpn.this) {
+            pw.println("Active package name: " + mPackage);
+            pw.println("Active vpn type: " + getActiveVpnType());
+            pw.println("NetworkCapabilities: " + mNetworkCapabilities);
+            if (isIkev2VpnRunner()) {
+                final IkeV2VpnRunner runner = ((IkeV2VpnRunner) mVpnRunner);
+                pw.println("Token: " + runner.mSessionKey);
+                pw.println("MOBIKE " + (runner.mMobikeEnabled ? "enabled" : "disabled"));
+                if (mDataStallSuspected) pw.println("Data stall suspected");
+                if (runner.mScheduledHandleDataStallFuture != null) {
+                    pw.println("Reset session scheduled");
+                }
+            }
+            pw.println("mUnderlyNetworkChanges (most recent first):");
+            pw.increaseIndent();
+            mUnderlyNetworkChanges.reverseDump(pw);
+            pw.decreaseIndent();
+
+            pw.println("mVpnManagerEvent (most recent first):");
+            pw.increaseIndent();
+            mVpnManagerEvents.reverseDump(pw);
+            pw.decreaseIndent();
+        }
+    }
 }