Skip adding ingress discard rule to legacy VPN

Some legacy VPNs need to receive packets to VPN address via
non-VPN interface.

Bug: 352424251
Test: CsIngressDiscardRuleTest
Change-Id: Iad06dc69c5bf5ccda476e89ed9b0fc1bc63d2ebe
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 953fd76..0a97028 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -9400,8 +9400,10 @@
      * interfaces.
      * Ingress discard rule is added to the address iff
      *   1. The address is not a link local address
-     *   2. The address is used by a single VPN interface and not used by any other
+     *   2. The address is used by a single non-Legacy VPN interface and not used by any other
      *      interfaces even non-VPN ones
+     * Ingress discard rule is not be added to Legacy VPN since some Legacy VPNs need to receive
+     * packet to VPN address via non-VPN interface.
      * This method can be called during network disconnects, when nai has already been removed from
      * mNetworkAgentInfos.
      *
@@ -9436,7 +9438,8 @@
         // for different network.
         final Set<Pair<InetAddress, String>> ingressDiscardRules = new ArraySet<>();
         for (final NetworkAgentInfo agent : nais) {
-            if (!agent.isVPN() || agent.isDestroyed()) {
+            if (!agent.isVPN() || agent.isDestroyed()
+                    || getVpnType(agent) == VpnManager.TYPE_VPN_LEGACY) {
                 continue;
             }
             final LinkProperties agentLp = (nai == agent) ? lp : agent.linkProperties;
diff --git a/tests/unit/java/com/android/server/connectivityservice/CSIngressDiscardRuleTests.kt b/tests/unit/java/com/android/server/connectivityservice/CSIngressDiscardRuleTests.kt
index 93f6e81..1ae77e5 100644
--- a/tests/unit/java/com/android/server/connectivityservice/CSIngressDiscardRuleTests.kt
+++ b/tests/unit/java/com/android/server/connectivityservice/CSIngressDiscardRuleTests.kt
@@ -27,6 +27,7 @@
 import android.net.NetworkCapabilities.TRANSPORT_WIFI
 import android.net.NetworkRequest
 import android.net.VpnManager.TYPE_VPN_SERVICE
+import android.net.VpnManager.TYPE_VPN_LEGACY
 import android.net.VpnTransportInfo
 import android.os.Build
 import androidx.test.filters.SmallTest
@@ -49,19 +50,20 @@
 private const val TIMEOUT_MS = 1_000L
 private const val LONG_TIMEOUT_MS = 5_000
 
-private fun vpnNc() = NetworkCapabilities.Builder()
-        .addTransportType(TRANSPORT_VPN)
-        .removeCapability(NET_CAPABILITY_NOT_VPN)
-        .addCapability(NET_CAPABILITY_NOT_VCN_MANAGED)
-        .setTransportInfo(
-                VpnTransportInfo(
-                        TYPE_VPN_SERVICE,
-                        "MySession12345",
-                        false /* bypassable */,
-                        false /* longLivedTcpConnectionsExpensive */
-                )
-        )
-        .build()
+private fun vpnNc(legacyVpn: Boolean = false) = NetworkCapabilities.Builder().apply {
+    addTransportType(TRANSPORT_VPN)
+    removeCapability(NET_CAPABILITY_NOT_VPN)
+    addCapability(NET_CAPABILITY_NOT_VCN_MANAGED)
+    val vpnType = if (legacyVpn) { TYPE_VPN_LEGACY } else { TYPE_VPN_SERVICE }
+    setTransportInfo(
+            VpnTransportInfo(
+                    vpnType,
+                    "MySession12345",
+                    false /* bypassable */,
+                    false /* longLivedTcpConnectionsExpensive */
+            )
+    )
+}.build()
 
 private fun wifiNc() = NetworkCapabilities.Builder()
         .addTransportType(TRANSPORT_WIFI)
@@ -310,4 +312,19 @@
         // IngressDiscardRule should not be added since feature is disabled
         verify(bpfNetMaps, never()).setIngressDiscardRule(any(), any())
     }
+
+    @Test
+    fun testVpnIngressDiscardRule_LegacyVpn() {
+        val nr = nr(TRANSPORT_VPN)
+        val cb = TestableNetworkCallback()
+        cm.registerNetworkCallback(nr, cb)
+        val nc = vpnNc(legacyVpn = true)
+        val lp = lp(VPN_IFNAME, IPV6_LINK_ADDRESS, LOCAL_IPV6_LINK_ADDRRESS)
+        val agent = Agent(nc = nc, lp = lp)
+        agent.connect()
+        cb.expectAvailableCallbacks(agent.network, validated = false)
+
+        // IngressDiscardRule should not be added to Legacy VPN
+        verify(bpfNetMaps, never()).setIngressDiscardRule(any(), any())
+    }
 }