Support decoding the new PREF64 RA option. (d6cc960f) · Commits · e / os / android_packages_modules_NetworkStack

common/netlinkclient/src/android/net/netlink/StructNdOptPref64.java

0 → 100644

+121 −0

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		/*
		* Copyright (C) 2020 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 android.net.netlink;

		import android.net.IpPrefix;
		import android.util.Log;

		import androidx.annotation.NonNull;

		import java.net.InetAddress;
		import java.net.UnknownHostException;
		import java.nio.ByteBuffer;

		/**
		* The PREF64 router advertisement option. RFC 8781.
		*
		* 0 1 2 3
		* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
		* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
		* \| Type \| Length \| Scaled Lifetime \| PLC \|
		* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
		* \| \|
		* + +
		* \| Highest 96 bits of the Prefix \|
		* + +
		* \| \|
		* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
		*
		*/
		public class StructNdOptPref64 {
		public static final int STRUCT_SIZE = 16;
		public static final int TYPE = 38;

		private static final String TAG = StructNdOptPref64.class.getSimpleName();

		/** The option type. Always ICMPV6_ND_OPTION_PREF64. */
		public final byte type;
		/** The length of the option in 8-byte units. Actually an unsigned 8-bit integer. */
		public final int length;
		/**
		* How many seconds the prefix is expected to remain valid.
		* Valid values are from 0 to 65528 in multiples of 8.
		*/
		public final int lifetime;
		/** The NAT64 prefix. */
		public final IpPrefix prefix;

		int plcToPrefixLength(int plc) {
		switch (plc) {
		case 0: return 96;
		case 1: return 64;
		case 2: return 56;
		case 3: return 48;
		case 4: return 40;
		case 5: return 32;
		default:
		throw new IllegalArgumentException("Invalid prefix length code " + plc);
		}
		}

		StructNdOptPref64(@NonNull ByteBuffer buf) {
		type = buf.get();
		length = buf.get();
		if (type != TYPE) throw new IllegalArgumentException("Invalid type " + type);
		if (length != 2) throw new IllegalArgumentException("Invalid length " + length);

		int scaledLifetimePlc = Short.toUnsignedInt(buf.getShort());
		lifetime = scaledLifetimePlc & 0xfff8;

		byte[] addressBytes = new byte[16];
		buf.get(addressBytes, 0, 12);
		InetAddress addr;
		try {
		addr = InetAddress.getByAddress(addressBytes);
		} catch (UnknownHostException e) {
		throw new AssertionError("16-byte array not valid InetAddress?");
		}
		prefix = new IpPrefix(addr, plcToPrefixLength(scaledLifetimePlc & 7));
		}

		/**
		* Parses an option from a {@link ByteBuffer}.
		*
		* @param buf The buffer from which to parse the option. The buffer's byte order must be
		* {@link java.nio.ByteOrder#BIG_ENDIAN}.
		* @return the parsed option, or {@code null} if the option could not be parsed successfully
		* (for example, if it was truncated, or if the prefix length code was wrong).
		*/
		public static StructNdOptPref64 parse(@NonNull ByteBuffer buf) {
		if (buf == null \|\| buf.remaining() < STRUCT_SIZE) return null;
		try {
		return new StructNdOptPref64(buf);
		} catch (IllegalArgumentException e) {
		// Not great, but better than throwing an exception that might crash the caller.
		// Convention in this package is that null indicates that the option was truncated, so
		// callers must already handle it.
		Log.d(TAG, "Invalid PREF64 option: " + e);
		return null;
		}
		}

		@Override
		@NonNull
		public String toString() {
		return String.format("NdOptPref64(%s, %d)", prefix, lifetime);
		}
		}

src/com/android/server/util/NetworkStackConstants.java

+1 −0

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		@@ -126,6 +126,7 @@ public final class NetworkStackConstants {
		public static final int ICMPV6_ND_OPTION_PIO = 3;
		public static final int ICMPV6_ND_OPTION_MTU = 5;
		public static final int ICMPV6_ND_OPTION_RDNSS = 25;
		public static final int ICMPV6_ND_OPTION_PREF64 = 38;


		public static final int ICMPV6_RA_HEADER_LEN = 16;

tests/unit/src/android/net/netlink/StructNdOptPref64Test.java

0 → 100644

+155 −0

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		/*
		* Copyright (C) 2019 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 android.net.netlink;

		import static org.junit.Assert.assertEquals;
		import static org.junit.Assert.assertNull;

		import android.net.IpPrefix;

		import androidx.test.filters.SmallTest;
		import androidx.test.runner.AndroidJUnit4;

		import libcore.util.HexEncoding;

		import org.junit.Test;
		import org.junit.runner.RunWith;

		import java.net.InetAddress;
		import java.nio.ByteBuffer;

		@RunWith(AndroidJUnit4.class)
		@SmallTest
		public class StructNdOptPref64Test {

		private static final String PREFIX1 = "64:ff9b::";
		private static final String PREFIX2 = "2001:db8:1:2:3:64::";

		private static byte[] prefixBytes(String addrString) throws Exception {
		InetAddress addr = InetAddress.getByName(addrString);
		byte[] prefixBytes = new byte[12];
		System.arraycopy(addr.getAddress(), 0, prefixBytes, 0, 12);
		return prefixBytes;
		}

		private static IpPrefix prefix(String addrString, int prefixLength) throws Exception {
		return new IpPrefix(InetAddress.getByName(addrString), prefixLength);
		}

		private void assertPref64OptMatches(int lifetime, IpPrefix prefix, StructNdOptPref64 opt) {
		assertEquals(StructNdOptPref64.TYPE, opt.type);
		assertEquals(2, opt.length);
		assertEquals(lifetime, opt.lifetime);
		assertEquals(prefix, opt.prefix);
		}

		/**
		* Returns the 2-byte "scaled lifetime and prefix length code" field: 13-bit lifetime, 3-bit PLC
		*/
		private short getPref64ScaledLifetimePlc(int lifetime, int prefixLengthCode) {
		return (short) ((lifetime & 0xfff8) \| (prefixLengthCode & 0x7));
		}

		private ByteBuffer makeNdOptPref64(int lifetime, byte[] prefix, int prefixLengthCode) {
		if (prefix.length != 12) throw new IllegalArgumentException("Prefix must be 12 bytes");

		ByteBuffer buf = ByteBuffer.allocate(16)
		.put((byte) StructNdOptPref64.TYPE)
		.put((byte) 2) // len=2 (16 bytes)
		.putShort(getPref64ScaledLifetimePlc(lifetime, prefixLengthCode))
		.put(prefix, 0, 12);

		buf.flip();
		return buf;
		}

		@Test
		public void testParseCannedOption() throws Exception {
		String hexBytes = "2602" // type=38, len=2 (16 bytes)
		+ "0088" // lifetime=136, PLC=0 (/96)
		+ "20010db80003000400050006"; // 2001:db8:3:4:5:6/96
		byte[] rawBytes = HexEncoding.decode(hexBytes);
		StructNdOptPref64 opt = StructNdOptPref64.parse(ByteBuffer.wrap(rawBytes));
		assertPref64OptMatches(136, prefix("2001:db8:3:4:5:6::", 96), opt);

		hexBytes = "2602" // type=38, len=2 (16 bytes)
		+ "2752" // lifetime=10064, PLC=2 (/56)
		+ "0064ff9b0000000000000000"; // 64:ff9b::/56
		rawBytes = HexEncoding.decode(hexBytes);
		opt = StructNdOptPref64.parse(ByteBuffer.wrap(rawBytes));
		assertPref64OptMatches(10064, prefix("64:ff9b::", 56), opt);
		}

		@Test
		public void testParsing() throws Exception {
		// Valid.
		ByteBuffer buf = makeNdOptPref64(600, prefixBytes(PREFIX1), 0);
		StructNdOptPref64 opt = StructNdOptPref64.parse(buf);
		assertPref64OptMatches(600, prefix(PREFIX1, 96), opt);

		// Valid, zero lifetime, /64.
		buf = makeNdOptPref64(0, prefixBytes(PREFIX1), 1);
		opt = StructNdOptPref64.parse(buf);
		assertPref64OptMatches(0, prefix(PREFIX1, 64), opt);

		// Valid, low lifetime, /56.
		buf = makeNdOptPref64(8, prefixBytes(PREFIX2), 2);
		opt = StructNdOptPref64.parse(buf);
		assertPref64OptMatches(8, prefix(PREFIX2, 56), opt);
		assertEquals(new IpPrefix("2001:db8:1::/56"), opt.prefix); // Prefix is truncated.

		// Valid, maximum lifetime, /32.
		buf = makeNdOptPref64(65528, prefixBytes(PREFIX2), 5);
		opt = StructNdOptPref64.parse(buf);
		assertPref64OptMatches(65528, prefix(PREFIX2, 32), opt);
		assertEquals(new IpPrefix("2001:db8::/32"), opt.prefix); // Prefix is truncated.

		// Lifetime not divisible by 8.
		buf = makeNdOptPref64(300, prefixBytes(PREFIX2), 0);
		opt = StructNdOptPref64.parse(buf);
		assertPref64OptMatches(296, prefix(PREFIX2, 96), opt);

		// Invalid prefix length codes.
		buf = makeNdOptPref64(600, prefixBytes(PREFIX1), 6);
		assertNull(StructNdOptPref64.parse(buf));
		buf = makeNdOptPref64(600, prefixBytes(PREFIX1), 7);
		assertNull(StructNdOptPref64.parse(buf));

		// Truncated to varying lengths...
		buf = makeNdOptPref64(600, prefixBytes(PREFIX1), 3);
		final int len = buf.limit();
		for (int i = 0; i < buf.limit() - 1; i++) {
		buf.flip();
		buf.limit(i);
		assertNull("Option truncated to " + i + " bytes, should have returned null",
		StructNdOptPref64.parse(buf));
		}
		buf.flip();
		buf.limit(len);
		// ... but otherwise OK.
		opt = StructNdOptPref64.parse(buf);
		assertPref64OptMatches(600, prefix(PREFIX1, 48), opt);
		}

		@Test
		public void testToString() throws Exception {
		ByteBuffer buf = makeNdOptPref64(600, prefixBytes(PREFIX1), 4);
		StructNdOptPref64 opt = StructNdOptPref64.parse(buf);
		assertPref64OptMatches(600, prefix(PREFIX1, 40), opt);
		assertEquals("NdOptPref64(64:ff9b::/40, 600)", opt.toString());
		}
		}