From 1bce54f2872d4806de0ecea75c8d74c0c1f9b0ed Mon Sep 17 00:00:00 2001
From: Remi NGUYEN VAN <reminv@google.com>
Date: Tue, 11 Jan 2022 11:47:12 +0900
Subject: [PATCH] Allow test+other networks to have specifiers

Allow adding a network specifier to networks that have two transports,
if one of them is TRANSPORT_TEST.

This allows creating test ethernet networks that have a network
specifier.

Bug: 175199512
Test: atest NetworkCapabilitiesTest
Change-Id: I2ced91926dff21fbe143258f33f3d42004a954c7
---
 .../src/android/net/NetworkCapabilities.java  |  9 ++--
 .../android/net/NetworkCapabilitiesTest.java  | 46 ++++++++++++-------
 2 files changed, 36 insertions(+), 19 deletions(-)

diff --git a/framework/src/android/net/NetworkCapabilities.java b/framework/src/android/net/NetworkCapabilities.java
index 84f7cbbd62..3afae670da 100644
--- a/framework/src/android/net/NetworkCapabilities.java
+++ b/framework/src/android/net/NetworkCapabilities.java
@@ -1500,9 +1500,12 @@ public final class NetworkCapabilities implements Parcelable {
      */
     public @NonNull NetworkCapabilities setNetworkSpecifier(
             @NonNull NetworkSpecifier networkSpecifier) {
-        if (networkSpecifier != null && Long.bitCount(mTransportTypes) != 1) {
-            throw new IllegalStateException("Must have a single transport specified to use " +
-                    "setNetworkSpecifier");
+        if (networkSpecifier != null
+                // Transport can be test, or test + a single other transport
+                && mTransportTypes != (1L << TRANSPORT_TEST)
+                && Long.bitCount(mTransportTypes & ~(1L << TRANSPORT_TEST)) != 1) {
+            throw new IllegalStateException("Must have a single non-test transport specified to "
+                    + "use setNetworkSpecifier");
         }
 
         mNetworkSpecifier = networkSpecifier;
diff --git a/tests/common/java/android/net/NetworkCapabilitiesTest.java b/tests/common/java/android/net/NetworkCapabilitiesTest.java
index 2a4df7adea..a44f543198 100644
--- a/tests/common/java/android/net/NetworkCapabilitiesTest.java
+++ b/tests/common/java/android/net/NetworkCapabilitiesTest.java
@@ -47,6 +47,7 @@ import static android.net.NetworkCapabilities.REDACT_FOR_LOCAL_MAC_ADDRESS;
 import static android.net.NetworkCapabilities.REDACT_FOR_NETWORK_SETTINGS;
 import static android.net.NetworkCapabilities.SIGNAL_STRENGTH_UNSPECIFIED;
 import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
+import static android.net.NetworkCapabilities.TRANSPORT_ETHERNET;
 import static android.net.NetworkCapabilities.TRANSPORT_TEST;
 import static android.net.NetworkCapabilities.TRANSPORT_USB;
 import static android.net.NetworkCapabilities.TRANSPORT_VPN;
@@ -668,25 +669,38 @@ public class NetworkCapabilitiesTest {
     @Test
     public void testSetNetworkSpecifierOnMultiTransportNc() {
         // Sequence 1: Transport + Transport + NetworkSpecifier
-        NetworkCapabilities nc1 = new NetworkCapabilities();
+        NetworkCapabilities.Builder nc1 = new NetworkCapabilities.Builder();
         nc1.addTransportType(TRANSPORT_CELLULAR).addTransportType(TRANSPORT_WIFI);
-        try {
-            nc1.setNetworkSpecifier(CompatUtil.makeEthernetNetworkSpecifier("eth0"));
-            fail("Cannot set NetworkSpecifier on a NetworkCapability with multiple transports!");
-        } catch (IllegalStateException expected) {
-            // empty
-        }
+        final NetworkSpecifier specifier = CompatUtil.makeEthernetNetworkSpecifier("eth0");
+        assertThrows("Cannot set NetworkSpecifier on a NetworkCapability with multiple transports!",
+                IllegalStateException.class,
+                () -> nc1.build().setNetworkSpecifier(specifier));
+        assertThrows("Cannot set NetworkSpecifier on a NetworkCapability with multiple transports!",
+                IllegalStateException.class,
+                () -> nc1.setNetworkSpecifier(specifier));
 
         // Sequence 2: Transport + NetworkSpecifier + Transport
-        NetworkCapabilities nc2 = new NetworkCapabilities();
-        nc2.addTransportType(TRANSPORT_CELLULAR).setNetworkSpecifier(
-                CompatUtil.makeEthernetNetworkSpecifier("testtap3"));
-        try {
-            nc2.addTransportType(TRANSPORT_WIFI);
-            fail("Cannot set a second TransportType of a network which has a NetworkSpecifier!");
-        } catch (IllegalStateException expected) {
-            // empty
-        }
+        NetworkCapabilities.Builder nc2 = new NetworkCapabilities.Builder();
+        nc2.addTransportType(TRANSPORT_CELLULAR).setNetworkSpecifier(specifier);
+
+        assertThrows("Cannot set a second TransportType of a network which has a NetworkSpecifier!",
+                IllegalStateException.class,
+                () -> nc2.build().addTransportType(TRANSPORT_WIFI));
+        assertThrows("Cannot set a second TransportType of a network which has a NetworkSpecifier!",
+                IllegalStateException.class,
+                () -> nc2.addTransportType(TRANSPORT_WIFI));
+    }
+
+    @Test @IgnoreUpTo(Build.VERSION_CODES.R) // New behavior in updatable NetworkCapabilities (S+)
+    public void testSetNetworkSpecifierOnTestMultiTransportNc() {
+        final NetworkSpecifier specifier = CompatUtil.makeEthernetNetworkSpecifier("eth0");
+        NetworkCapabilities nc = new NetworkCapabilities.Builder()
+                .addTransportType(TRANSPORT_TEST)
+                .addTransportType(TRANSPORT_ETHERNET)
+                .setNetworkSpecifier(specifier)
+                .build();
+        // Adding a specifier did not crash with 2 transports if one is TEST
+        assertEquals(specifier, nc.getNetworkSpecifier());
     }
 
     @Test