Create RouterAdvertisementResponder

This is useful for tests that need a provisioned tap interface.

Test: TH
Change-Id: I9a2eb3d8697bbcbfdb65563da609534b929a0715

1 files changed, 123 insertions, 0 deletions

diff --git a/common/testutils/devicetests/com/android/testutils/RouterAdvertisementResponder.java b/common/testutils/devicetests/com/android/testutils/RouterAdvertisementResponder.java
new file mode 100644
index 00000000..4ad93d85
--- /dev/null
+++ b/common/testutils/devicetests/com/android/testutils/RouterAdvertisementResponder.java
@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.testutils;
+
+import static android.system.OsConstants.IPPROTO_ICMPV6;
+
+import static com.android.net.module.util.NetworkStackConstants.ETHER_ADDR_LEN;
+import static com.android.net.module.util.NetworkStackConstants.ETHER_SRC_ADDR_OFFSET;
+import static com.android.net.module.util.NetworkStackConstants.ETHER_TYPE_IPV6;
+import static com.android.net.module.util.NetworkStackConstants.ICMPV6_ROUTER_SOLICITATION;
+import static com.android.net.module.util.NetworkStackConstants.IPV6_ADDR_ALL_NODES_MULTICAST;
+import static com.android.net.module.util.NetworkStackConstants.IPV6_ADDR_ALL_ROUTERS_MULTICAST;
+import static com.android.net.module.util.NetworkStackConstants.PIO_FLAG_AUTONOMOUS;
+import static com.android.net.module.util.NetworkStackConstants.PIO_FLAG_ON_LINK;
+
+import android.net.InetAddresses;
+import android.net.IpPrefix;
+import android.net.LinkAddress;
+import android.net.MacAddress;
+import android.util.Pair;
+
+import com.android.net.module.util.Ipv6Utils;
+import com.android.net.module.util.Struct;
+import com.android.net.module.util.structs.EthernetHeader;
+import com.android.net.module.util.structs.Icmpv6Header;
+import com.android.net.module.util.structs.Ipv6Header;
+import com.android.net.module.util.structs.PrefixInformationOption;
+import com.android.net.module.util.structs.RdnssOption;
+
+import java.io.IOException;
+import java.net.Inet6Address;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * RA responder class useful for tests that require a provisioned interface.
+ */
+public class RouterAdvertisementResponder extends PacketResponder {
+    private static final String TAG = "RouterAdvertisementResponder";
+    private static final LinkAddress SLAAC_PREFIX = new LinkAddress("2001:db8::/64");
+    private static final Inet6Address DNS_SERVER =
+            (Inet6Address) InetAddresses.parseNumericAddress("2001:4860:4860::64");
+    private final TapPacketReader mPacketReader;
+    private final List<Pair<MacAddress, Inet6Address>> mRouterList = new ArrayList<>();
+
+    public RouterAdvertisementResponder(TapPacketReader packetReader) {
+        super(packetReader, RouterAdvertisementResponder::isRouterSolicitation, TAG);
+        mPacketReader = packetReader;
+    }
+
+    private static boolean isRouterSolicitation(byte[] packet) {
+        final ByteBuffer buffer = ByteBuffer.wrap(packet);
+        final EthernetHeader ethHeader = Struct.parse(EthernetHeader.class, buffer);
+        if (ethHeader.etherType != ETHER_TYPE_IPV6) {
+            return false;
+        }
+        final Ipv6Header ipv6Header = Struct.parse(Ipv6Header.class, buffer);
+        if (ipv6Header.nextHeader != IPPROTO_ICMPV6
+                || !ipv6Header.dstIp.equals(IPV6_ADDR_ALL_ROUTERS_MULTICAST)) {
+            return false;
+        }
+        final Icmpv6Header icmpv6Header = Struct.parse(Icmpv6Header.class, buffer);
+        return icmpv6Header.type == ICMPV6_ROUTER_SOLICITATION;
+    }
+
+    /**
+     * Adds a new router to be advertised.
+     * @param mac the mac address of the router.
+     * @param ip the link-local address of the router.
+     */
+    public void addRouterEntry(MacAddress mac, Inet6Address ip) {
+        mRouterList.add(new Pair<>(mac, ip));
+    }
+
+    private ByteBuffer buildPrefixOption() {
+        return PrefixInformationOption.build(
+                new IpPrefix(SLAAC_PREFIX.getAddress(), SLAAC_PREFIX.getPrefixLength()),
+                (byte) (PIO_FLAG_ON_LINK | PIO_FLAG_AUTONOMOUS), 3600/*valid lifetime*/,
+                3600/*preferred lifetime*/);
+    }
+
+    private ByteBuffer buildRdnssOption() {
+        return RdnssOption.build(3600/*lifetime, must be at least 120*/, DNS_SERVER);
+    }
+
+    private ByteBuffer buildRaPacket(MacAddress srcMac, MacAddress dstMac, Inet6Address srcIp) {
+        return Ipv6Utils.buildRaPacket(srcMac, dstMac, srcIp, IPV6_ADDR_ALL_NODES_MULTICAST,
+                (byte) 0 /*M=0, O=0*/, 3600 /*lifetime*/, 0 /*reachableTime, unspecified*/,
+                0/*retransTimer, unspecified*/, buildPrefixOption(), buildRdnssOption());
+    }
+
+    @Override
+    protected void replyToPacket(byte[] packet, TapPacketReader reader) {
+        final MacAddress srcMac = MacAddress.fromBytes(
+                Arrays.copyOfRange(packet, ETHER_SRC_ADDR_OFFSET,
+                        ETHER_SRC_ADDR_OFFSET + ETHER_ADDR_LEN));
+
+        for (Pair<MacAddress, Inet6Address> it : mRouterList) {
+            final ByteBuffer raResponse = buildRaPacket(it.first, srcMac, it.second);
+            try {
+                reader.sendResponse(raResponse);
+            } catch (IOException e) {
+                throw new RuntimeException("Failed to send RA");
+            }
+        }
+    }
+}