[TestOnly] Replace isRouterAdvertisement with isIcmpv6Type

Test: atest EthernetTetheringTest
Change-Id: I5dca7a05a982139d8fc6f8272c8b829b74a34722
diff --git a/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java b/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java
index ad2cbbc..97c1401 100644
--- a/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java
+++ b/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java
@@ -28,7 +28,6 @@
 import static android.net.TetheringManager.TETHERING_ETHERNET;
 import static android.net.TetheringTester.RemoteResponder;
 import static android.net.TetheringTester.isIcmpv6Type;
-import static android.system.OsConstants.IPPROTO_ICMPV6;
 import static android.system.OsConstants.IPPROTO_IP;
 import static android.system.OsConstants.IPPROTO_IPV6;
 import static android.system.OsConstants.IPPROTO_UDP;
@@ -85,7 +84,6 @@
 import com.android.net.module.util.bpf.TetherStatsKey;
 import com.android.net.module.util.bpf.TetherStatsValue;
 import com.android.net.module.util.structs.EthernetHeader;
-import com.android.net.module.util.structs.Icmpv6Header;
 import com.android.net.module.util.structs.Ipv4Header;
 import com.android.net.module.util.structs.Ipv6Header;
 import com.android.net.module.util.structs.UdpHeader;
@@ -146,6 +144,7 @@
     // Per TX UDP packet size: ethhdr (14) + iphdr (20) + udphdr (8) + payload (2) = 44 bytes.
     private static final int TX_UDP_PACKET_SIZE = 44;
     private static final int TX_UDP_PACKET_COUNT = 123;
+    private static final long WAIT_RA_TIMEOUT_MS = 2000;
 
     private static final LinkAddress TEST_IP4_ADDR = new LinkAddress("10.0.0.1/8");
     private static final LinkAddress TEST_IP6_ADDR = new LinkAddress("2001:db8:1::101/64");
@@ -329,27 +328,13 @@
 
     }
 
-    private static boolean isRouterAdvertisement(byte[] pkt) {
-        if (pkt == null) return false;
-
-        ByteBuffer buf = ByteBuffer.wrap(pkt);
-
-        final EthernetHeader ethHdr = Struct.parse(EthernetHeader.class, buf);
-        if (ethHdr.etherType != ETHER_TYPE_IPV6) return false;
-
-        final Ipv6Header ipv6Hdr = Struct.parse(Ipv6Header.class, buf);
-        if (ipv6Hdr.nextHeader != (byte) IPPROTO_ICMPV6) return false;
-
-        final Icmpv6Header icmpv6Hdr = Struct.parse(Icmpv6Header.class, buf);
-        return icmpv6Hdr.type == (short) ICMPV6_ROUTER_ADVERTISEMENT;
-    }
-
-    private static void expectRouterAdvertisement(TapPacketReader reader, String iface,
+    private static void waitForRouterAdvertisement(TapPacketReader reader, String iface,
             long timeoutMs) {
         final long deadline = SystemClock.uptimeMillis() + timeoutMs;
         do {
             byte[] pkt = reader.popPacket(timeoutMs);
-            if (isRouterAdvertisement(pkt)) return;
+            if (isIcmpv6Type(pkt, true /* hasEth */, ICMPV6_ROUTER_ADVERTISEMENT)) return;
+
             timeoutMs = deadline - SystemClock.uptimeMillis();
         } while (timeoutMs > 0);
         fail("Did not receive router advertisement on " + iface + " after "
@@ -401,7 +386,7 @@
         // before the reader is started.
         mDownstreamReader = makePacketReader(mDownstreamIface);
 
-        expectRouterAdvertisement(mDownstreamReader, iface, 2000 /* timeoutMs */);
+        waitForRouterAdvertisement(mDownstreamReader, iface, WAIT_RA_TIMEOUT_MS);
         expectLocalOnlyAddresses(iface);
     }