From d9695aced3cb2c6c1cad646bd06d83af4d89357c Mon Sep 17 00:00:00 2001
From: Benedict Wong <benedictwong@google.com>
Date: Fri, 14 May 2021 15:01:16 -0700
Subject: [PATCH] Make VcnTransportInfo unparcel to null if no data contained

When VcnTransportInfo is redacted, it contains no useful information. In
order to preserve the abstraction, the VcnTransportInfo should be
unparcelled to null


Bug: 8675309
Test: atest VcnTransportInfoTest
Change-Id: Ia9dbb9f259027acc74004eb1207e0a13cea56088
---
 .../android/net/vcn/VcnTransportInfo.java     | 24 +++++++++++--
 .../android/net/vcn/VcnTransportInfoTest.java | 36 +++++++++++++++----
 2 files changed, 52 insertions(+), 8 deletions(-)

diff --git a/core/java/android/net/vcn/VcnTransportInfo.java b/core/java/android/net/vcn/VcnTransportInfo.java
index 1f1818420b561..25a257423ce2a 100644
--- a/core/java/android/net/vcn/VcnTransportInfo.java
+++ b/core/java/android/net/vcn/VcnTransportInfo.java
@@ -16,11 +16,12 @@
 
 package android.net.vcn;
 
-import static android.net.NetworkCapabilities.REDACT_NONE;
+import static android.net.NetworkCapabilities.REDACT_FOR_NETWORK_SETTINGS;
 import static android.telephony.SubscriptionManager.INVALID_SUBSCRIPTION_ID;
 
 import android.annotation.NonNull;
 import android.annotation.Nullable;
+import android.net.NetworkCapabilities;
 import android.net.TransportInfo;
 import android.net.wifi.WifiInfo;
 import android.os.Parcel;
@@ -108,13 +109,24 @@ public class VcnTransportInfo implements TransportInfo, Parcelable {
     @Override
     @NonNull
     public TransportInfo makeCopy(long redactions) {
+        if ((redactions & NetworkCapabilities.REDACT_FOR_NETWORK_SETTINGS) != 0) {
+            return new VcnTransportInfo(null, INVALID_SUBSCRIPTION_ID);
+        }
+
         return new VcnTransportInfo(
                 (mWifiInfo == null) ? null : mWifiInfo.makeCopy(redactions), mSubId);
     }
 
     @Override
     public long getApplicableRedactions() {
-        return (mWifiInfo == null) ? REDACT_NONE : mWifiInfo.getApplicableRedactions();
+        long redactions = REDACT_FOR_NETWORK_SETTINGS;
+
+        // Add additional wifi redactions if necessary
+        if (mWifiInfo != null) {
+            redactions |= mWifiInfo.getApplicableRedactions();
+        }
+
+        return redactions;
     }
 
     /** {@inheritDoc} */
@@ -135,6 +147,14 @@ public class VcnTransportInfo implements TransportInfo, Parcelable {
                 public VcnTransportInfo createFromParcel(Parcel in) {
                     final int subId = in.readInt();
                     final WifiInfo wifiInfo = in.readParcelable(null);
+
+                    // If all fields are their null values, return null TransportInfo to avoid
+                    // leaking information about this being a VCN Network (instead of macro
+                    // cellular, etc)
+                    if (wifiInfo == null && subId == INVALID_SUBSCRIPTION_ID) {
+                        return null;
+                    }
+
                     return new VcnTransportInfo(wifiInfo, subId);
                 }
 
diff --git a/tests/vcn/java/android/net/vcn/VcnTransportInfoTest.java b/tests/vcn/java/android/net/vcn/VcnTransportInfoTest.java
index 00a0bffa15c57..19df3c75266c5 100644
--- a/tests/vcn/java/android/net/vcn/VcnTransportInfoTest.java
+++ b/tests/vcn/java/android/net/vcn/VcnTransportInfoTest.java
@@ -17,7 +17,6 @@
 package android.net.vcn;
 
 import static android.net.NetworkCapabilities.REDACT_FOR_ACCESS_FINE_LOCATION;
-import static android.net.NetworkCapabilities.REDACT_FOR_LOCAL_MAC_ADDRESS;
 import static android.net.NetworkCapabilities.REDACT_FOR_NETWORK_SETTINGS;
 import static android.net.NetworkCapabilities.REDACT_NONE;
 import static android.telephony.SubscriptionManager.INVALID_SUBSCRIPTION_ID;
@@ -26,12 +25,15 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNull;
 
+import android.net.NetworkCapabilities;
 import android.net.wifi.WifiConfiguration;
 import android.net.wifi.WifiInfo;
 import android.os.Parcel;
 
 import org.junit.Test;
 
+import java.util.Arrays;
+
 public class VcnTransportInfoTest {
     private static final int SUB_ID = 1;
     private static final int NETWORK_ID = 5;
@@ -55,6 +57,19 @@ public class VcnTransportInfoTest {
         assertEquals(INVALID_SUBSCRIPTION_ID, WIFI_UNDERLYING_INFO.getSubId());
     }
 
+    @Test
+    public void testMakeCopyRedactForNetworkSettings() {
+        for (VcnTransportInfo info : Arrays.asList(CELL_UNDERLYING_INFO, WIFI_UNDERLYING_INFO)) {
+            assertEquals(
+                    INVALID_SUBSCRIPTION_ID,
+                    ((VcnTransportInfo) info.makeCopy(REDACT_FOR_NETWORK_SETTINGS))
+                            .getSubId());
+            assertNull(
+                    ((VcnTransportInfo) info.makeCopy(REDACT_FOR_NETWORK_SETTINGS))
+                            .getWifiInfo());
+        }
+    }
+
     @Test
     public void testMakeCopyRedactForAccessFineLocation() {
         assertEquals(
@@ -75,11 +90,20 @@ public class VcnTransportInfoTest {
     }
 
     @Test
-    public void testApplicableRedactions() {
-        assertEquals(REDACT_NONE, CELL_UNDERLYING_INFO.getApplicableRedactions());
-        assertEquals(REDACT_FOR_ACCESS_FINE_LOCATION | REDACT_FOR_LOCAL_MAC_ADDRESS
-                        | REDACT_FOR_NETWORK_SETTINGS,
-                WIFI_UNDERLYING_INFO.getApplicableRedactions());
+    public void testParcelUnparcel() {
+        verifyParcelingIsNull(CELL_UNDERLYING_INFO);
+        verifyParcelingIsNull(WIFI_UNDERLYING_INFO);
+    }
+
+    private void verifyParcelingIsNull(VcnTransportInfo vcnTransportInfo) {
+        VcnTransportInfo redacted = (VcnTransportInfo) vcnTransportInfo.makeCopy(
+                NetworkCapabilities.REDACT_FOR_NETWORK_SETTINGS);
+
+        Parcel parcel = Parcel.obtain();
+        redacted.writeToParcel(parcel, 0 /* flags */);
+        parcel.setDataPosition(0);
+
+        assertNull(VcnTransportInfo.CREATOR.createFromParcel(parcel));
     }
 
     @Test