Merge "Support parsing ND option messages." (9115abd5) · Commits · e / os / android_packages_modules_NetworkStack

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

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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 java.nio.ByteBuffer;

		/**
		* Base class for IPv6 neighbour discovery options.
		*/
		public class NdOption {
		public static final int STRUCT_SIZE = 2;

		/** The option type. */
		public final byte type;
		/** The length of the option in 8-byte units. Actually an unsigned 8-bit integer */
		public final int length;

		/** Constructs a new NdOption. */
		public NdOption(byte type, int length) {
		this.type = type;
		this.length = length;
		}

		/**
		* Parses a neighbour discovery option.
		*
		* Parses (and consumes) the option if it is of a known type. If the option is of an unknown
		* type, advances the buffer (so the caller can continue parsing if desired) and returns
		* {@link #UNKNOWN}. If the option claims a length of 0, returns null because parsing cannot
		* continue.
		*
		* No checks are performed on the length other than ensuring it is not 0, so if a caller wants
		* to deal with options that might overflow the structure that contains them, it must explicitly
		* set the buffer's limit to the position at which that structure ends.
		*
		* @param buf the buffer to parse.
		* @return a subclass of {@link NdOption}, or {@code null} for an unknown or malformed option.
		*/
		public static NdOption parse(ByteBuffer buf) {
		if (buf == null \|\| buf.remaining() < STRUCT_SIZE) return null;

		// Peek the type without advancing the buffer.
		byte type = buf.get(buf.position());
		int length = Byte.toUnsignedInt(buf.get(buf.position() + 1));
		if (length == 0) return null;

		switch (type) {
		case StructNdOptPref64.TYPE:
		return StructNdOptPref64.parse(buf);

		default:
		int newPosition = Math.min(buf.limit(), buf.position() + length * 8);
		buf.position(newPosition);
		return UNKNOWN;
		}
		}

		@Override
		public String toString() {
		return String.format("NdOption(%d, %d)", Byte.toUnsignedInt(type), length);
		}

		public static final NdOption UNKNOWN = new NdOption((byte) 0, 0);
		}

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

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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 static android.system.OsConstants.AF_INET6;

		import androidx.annotation.NonNull;

		import java.net.Inet6Address;
		import java.net.InetAddress;
		import java.net.UnknownHostException;
		import java.nio.BufferUnderflowException;
		import java.nio.ByteBuffer;
		import java.nio.ByteOrder;

		/**
		* A NetlinkMessage subclass for RTM_NEWNDUSEROPT messages.
		*/
		public class NduseroptMessage extends NetlinkMessage {
		public static final int STRUCT_SIZE = 16;

		static final int NDUSEROPT_SRCADDR = 1;

		/** The address family. Presumably always AF_INET6. */
		public final byte family;
		/**
		* The total length in bytes of the options that follow this structure.
		* Actually a 16-bit unsigned integer.
		*/
		public final int opts_len;
		/** The interface index on which the options were received. */
		public final int ifindex;
		/** The ICMP type of the packet that contained the options. */
		public final byte icmp_type;
		/** The ICMP code of the packet that contained the options. */
		public final byte icmp_code;

		/**
		* ND option that was in this message.
		* Even though the length field is called "opts_len", the kernel only ever sends one option per
		* message. It is unlikely that this will ever change as it would break existing userspace code.
		* But if it does, we can simply update this code, since userspace is typically newer than the
		* kernel.
		*/
		public final NdOption option;

		/** The IP address that sent the packet containing the option. */
		public final InetAddress srcaddr;

		NduseroptMessage(@NonNull StructNlMsgHdr header, @NonNull ByteBuffer buf)
		throws UnknownHostException {
		super(header);

		// The structure itself.
		buf.order(ByteOrder.nativeOrder());
		family = buf.get();
		buf.get(); // Skip 1 byte of padding.
		opts_len = Short.toUnsignedInt(buf.getShort());
		ifindex = buf.getInt();
		icmp_type = buf.get();
		icmp_code = buf.get();
		buf.order(ByteOrder.BIG_ENDIAN);
		buf.position(buf.position() + 6); // Skip 6 bytes of padding.

		// The ND option.
		// Ensure we don't read past opts_len even if the option length is invalid.
		// Note that this check is not really necessary since if the option length is not valid,
		// this struct won't be very useful to the caller.
		int oldLimit = buf.limit();
		buf.limit(STRUCT_SIZE + opts_len);
		try {
		option = NdOption.parse(buf);
		} finally {
		buf.limit(oldLimit);
		}

		// The source address.
		int newPosition = STRUCT_SIZE + opts_len;
		if (newPosition >= buf.limit()) {
		throw new IllegalArgumentException("ND options extend past end of buffer");
		}
		buf.position(newPosition);

		StructNlAttr nla = StructNlAttr.parse(buf);
		if (nla == null \|\| nla.nla_type != NDUSEROPT_SRCADDR \|\| nla.nla_value == null) {
		throw new IllegalArgumentException("Invalid source address in ND useropt");
		}
		if (family == AF_INET6) {
		// InetAddress.getByAddress only looks at the ifindex if the address type needs one.
		srcaddr = Inet6Address.getByAddress(null /* hostname */, nla.nla_value, ifindex);
		} else {
		srcaddr = InetAddress.getByAddress(nla.nla_value);
		}
		}

		/**
		* Parses a StructNduseroptmsg from a {@link ByteBuffer}.
		*
		* @param header the netlink message header.
		* @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 NduseroptMessage parse(@NonNull StructNlMsgHdr header, @NonNull ByteBuffer buf) {
		if (buf == null \|\| buf.remaining() < STRUCT_SIZE) return null;
		try {
		return new NduseroptMessage(header, buf);
		} catch (IllegalArgumentException \| UnknownHostException \| BufferUnderflowException 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.
		return null;
		}
		}

		@Override
		public String toString() {
		return String.format("Nduseroptmsg(%d, %d, %d, %d, %d, %s)",
		family, opts_len, ifindex, Byte.toUnsignedInt(icmp_type),
		Byte.toUnsignedInt(icmp_code), srcaddr.getHostAddress());
		}
		}

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

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		@@ -64,6 +64,8 @@ public class NetlinkMessage {
		return (NetlinkMessage) RtNetlinkNeighborMessage.parse(nlmsghdr, byteBuffer);
		case NetlinkConstants.SOCK_DIAG_BY_FAMILY:
		return (NetlinkMessage) InetDiagMessage.parse(nlmsghdr, byteBuffer);
		case NetlinkConstants.RTM_NEWNDUSEROPT:
		return (NetlinkMessage) NduseroptMessage.parse(nlmsghdr, byteBuffer);
		default:
		if (nlmsghdr.nlmsg_type <= NetlinkConstants.NLMSG_MAX_RESERVED) {
		// Netlink control message. Just parse the header for now,

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

+3 −8

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		@@ -41,16 +41,12 @@ import java.nio.ByteBuffer;
		* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
		*
		*/
		public class StructNdOptPref64 {
		public class StructNdOptPref64 extends NdOption {
		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.
		@@ -72,9 +68,8 @@ public class StructNdOptPref64 {
		}
		}

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

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

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

		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.nio.ByteBuffer;

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

		// Pick ifindices that are high enough that they will "never" be an existing interface index,
		// and always be represented numerically in the address. That way, the test will never need to
		// determine the interface names corresponding to these indices. That simplifies the code and
		// makes the test more useful because determining interface names might require permissions.
		private static final int IFINDEX1 = 15715755;
		private static final int IFINDEX2 = 1431655765;

		// IPv6, 0 bytes of options, interface index 15715755, type 134 (RA), code 0, padding.
		private static final String HDR_EMPTY = "0a00" + "0000" + "abcdef00" + "8600000000000000";

		// IPv6, 16 bytes of options, interface index 1431655765, type 134 (RA), code 0, padding.
		private static final String HDR_16BYTE = "0a00" + "1000" + "55555555" + "8600000000000000";

		// IPv6, 32 bytes of options, interface index 1431655765, type 134 (RA), code 0, padding.
		private static final String HDR_32BYTE = "0a00" + "2000" + "55555555" + "8600000000000000";

		// PREF64 option, 2001:db8:3:4:5:6::/96, lifetime=10064
		private static final String OPT_PREF64 = "2602" + "2750" + "20010db80003000400050006";

		// Length 20, NDUSEROPT_SRCADDR, fe80:2:3:4:5:6:7:8
		private static final String NLA_SRCADDR = "1400" + "0100" + "fe800002000300040005000600070008";

		private static final String SRCADDR1 = "fe80:2:3:4:5:6:7:8%" + IFINDEX1;
		private static final String SRCADDR2 = "fe80:2:3:4:5:6:7:8%" + IFINDEX2;

		private static final String MSG_EMPTY = HDR_EMPTY + NLA_SRCADDR;
		private static final String MSG_PREF64 = HDR_16BYTE + OPT_PREF64 + NLA_SRCADDR;

		@Test
		public void testParsing() {
		NduseroptMessage msg = parseNduseroptMessage(toBuffer(MSG_EMPTY));
		assertMatches((byte) 10, 0, IFINDEX1, (byte) 134, (byte) 0, SRCADDR1, msg);
		assertNull(msg.option);

		msg = parseNduseroptMessage(toBuffer(MSG_PREF64));
		assertMatches((byte) 10, 16, IFINDEX2, (byte) 134, (byte) 0, SRCADDR2, msg);
		assertPref64Option("2001:db8:3:4:5:6::/96", msg.option);
		}

		@Test
		public void testUnknownOption() {
		ByteBuffer buf = toBuffer(MSG_PREF64);
		// Replace the PREF64 option type (38) with an unknown option number.
		final int optionStart = NduseroptMessage.STRUCT_SIZE;
		assertEquals(38, buf.get(optionStart));
		buf.put(optionStart, (byte) 42);

		NduseroptMessage msg = parseNduseroptMessage(buf);
		assertMatches((byte) 10, 16, IFINDEX2, (byte) 134, (byte) 0, SRCADDR2, msg);
		assertEquals(NdOption.UNKNOWN, msg.option);

		buf.flip();
		assertEquals(42, buf.get(optionStart));
		buf.put(optionStart, (byte) 38);

		msg = parseNduseroptMessage(buf);
		assertMatches((byte) 10, 16, IFINDEX2, (byte) 134, (byte) 0, SRCADDR2, msg);
		assertPref64Option("2001:db8:3:4:5:6::/96", msg.option);
		}

		@Test
		public void testZeroLengthOption() {
		// Make sure an unknown option with a 0-byte length is ignored and parsing continues with
		// the address, which comes after it.
		final String hexString = HDR_16BYTE + "00000000000000000000000000000000" + NLA_SRCADDR;
		ByteBuffer buf = toBuffer(hexString);
		assertEquals(52, buf.limit());
		NduseroptMessage msg = parseNduseroptMessage(buf);
		assertMatches((byte) 10, 16, IFINDEX2, (byte) 134, (byte) 0, SRCADDR2, msg);
		assertNull(msg.option);
		}

		@Test
		public void testTooLongOption() {
		// Make sure that if an option's length is too long, it's ignored and parsing continues with
		// the address, which comes after it.
		final String hexString = HDR_16BYTE + "26030000000000000000000000000000" + NLA_SRCADDR;
		ByteBuffer buf = toBuffer(hexString);
		assertEquals(52, buf.limit());
		NduseroptMessage msg = parseNduseroptMessage(buf);
		assertMatches((byte) 10, 16, IFINDEX2, (byte) 134, (byte) 0, SRCADDR2, msg);
		assertNull(msg.option);
		}

		@Test
		public void testOptionsTooLong() {
		// Header claims 32 bytes of options. Buffer ends before options end.
		String hexString = HDR_32BYTE + OPT_PREF64;
		ByteBuffer buf = toBuffer(hexString);
		assertEquals(32, buf.limit());
		assertNull(NduseroptMessage.parse(toBuffer(hexString)));

		// Header claims 32 bytes of options. Buffer ends at end of options with no source address.
		hexString = HDR_32BYTE + OPT_PREF64 + OPT_PREF64;
		buf = toBuffer(hexString);
		assertEquals(48, buf.limit());
		assertNull(NduseroptMessage.parse(toBuffer(hexString)));
		}

		@Test
		public void testTruncation() {
		final int optLen = MSG_PREF64.length() / 2; // 1 byte = 2 hex chars
		for (int len = 0; len < optLen; len++) {
		ByteBuffer buf = toBuffer(MSG_PREF64.substring(0, len * 2));
		NduseroptMessage msg = parseNduseroptMessage(buf);
		if (len < optLen) {
		assertNull(msg);
		} else {
		assertNotNull(msg);
		assertPref64Option("2001:db8:3:4:5:6::/96", msg.option);
		}
		}
		}

		@Test
		public void testToString() {
		NduseroptMessage msg = parseNduseroptMessage(toBuffer(MSG_PREF64));
		assertNotNull(msg);
		assertEquals("Nduseroptmsg(10, 16, 1431655765, 134, 0, fe80:2:3:4:5:6:7:8%1431655765)",
		msg.toString());
		}

		// Convenience method to parse a NduseroptMessage that's not part of a netlink message.
		private NduseroptMessage parseNduseroptMessage(ByteBuffer buf) {
		return NduseroptMessage.parse(null, buf);
		}

		private ByteBuffer toBuffer(String hexString) {
		return ByteBuffer.wrap(HexEncoding.decode(hexString));
		}

		private void assertMatches(byte family, int optsLen, int ifindex, byte icmpType,
		byte icmpCode, String srcaddr, NduseroptMessage msg) {
		assertNotNull(msg);
		assertEquals(family, msg.family);
		assertEquals(ifindex, msg.ifindex);
		assertEquals(optsLen, msg.opts_len);
		assertEquals(icmpType, msg.icmp_type);
		assertEquals(icmpCode, msg.icmp_code);
		assertEquals(srcaddr, msg.srcaddr.getHostAddress());
		}

		private void assertPref64Option(String prefix, NdOption opt) {
		assertNotNull(opt);
		assertTrue(opt instanceof StructNdOptPref64);
		StructNdOptPref64 pref64Opt = (StructNdOptPref64) opt;
		assertEquals(new IpPrefix(prefix), pref64Opt.prefix);
		}
		}