Merge "Introduce RoughtimeClient" (5448cd6e) · Commits · e / os / android_frameworks_base

core/java/android/net/RoughtimeClient.java

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		/*
		* Copyright (C) 2016 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;

		import android.os.SystemClock;
		import android.util.Log;

		import java.io.IOException;
		import java.net.DatagramPacket;
		import java.net.DatagramSocket;
		import java.net.InetAddress;
		import java.nio.ByteBuffer;
		import java.nio.ByteOrder;
		import java.security.MessageDigest;
		import java.security.SecureRandom;
		import java.util.ArrayList;
		import java.util.Arrays;
		import java.util.Collections;
		import java.util.HashMap;

		/**
		* {@hide}
		*
		* Simple Roughtime client class for retrieving network time.
		*/
		public class RoughtimeClient
		{
		private static final String TAG = "RoughtimeClient";
		private static final boolean ENABLE_DEBUG = true;

		private static final int ROUGHTIME_PORT = 5333;

		private static final int MIN_REQUEST_SIZE = 1024;

		private static final int NONCE_SIZE = 64;

		private static final int MAX_DATAGRAM_SIZE = 65507;

		private final SecureRandom random = new SecureRandom();

		/**
		* Tag values. Exposed for use in tests only.
		*/
		protected static enum Tag {
		/**
		* Nonce used to initiate a transaction.
		*/
		NONC(0x434e4f4e),

		/**
		* Signed portion of a response.
		**/
		SREP(0x50455253),

		/**
		* Pad data. Always the largest tag lexicographically.
		*/
		PAD(0xff444150),

		/**
		* A signature for a neighboring SREP.
		*/
		SIG(0x474953),

		/**
		* Server certificate.
		*/
		CERT(0x54524543),

		/**
		* Position in the Merkle tree.
		*/
		INDX(0x58444e49),

		/**
		* Upward path in the Merkle tree.
		*/
		PATH(0x48544150),

		/**
		* Midpoint of the time interval in the response.
		*/
		MIDP(0x5044494d),

		/**
		* Radius of the time interval in the response.
		*/
		RADI(0x49444152),

		/**
		* Root of the Merkle tree.
		*/
		ROOT(0x544f4f52),

		/**
		* Delegation from the long term key to an online key.
		*/
		DELE(0x454c4544),

		/**
		* Online public key.
		*/
		PUBK(0x4b425550),

		/**
		* Earliest midpoint time the given PUBK can authenticate.
		*/
		MINT(0x544e494d),

		/**
		* Latest midpoint time the given PUBK can authenticate.
		*/
		MAXT(0x5458414d);

		private final int value;

		Tag(int value) {
		this.value = value;
		}

		private int value() {
		return value;
		}
		}

		/**
		* A result retrieved from a roughtime server.
		*/
		private static class Result {
		public long midpoint;
		public int radius;
		public long collectionTime;
		}

		/**
		* A Roughtime protocol message. Functionally a serializable map from Tags
		* to byte arrays.
		*/
		protected static class Message {
		private HashMap<Integer,byte[]> items = new HashMap<Integer,byte[]>();
		public int padSize = 0;

		public Message() {}

		/**
		* Set the given data for the given tag.
		*/
		public void put(Tag tag, byte[] data) {
		put(tag.value(), data);
		}

		private void put(int tag, byte[] data) {
		items.put(tag, data);
		}

		/**
		* Get the data associated with the given tag.
		*/
		public byte[] get(Tag tag) {
		return items.get(tag.value());
		}

		/**
		* Get the data associated with the given tag and decode it as a 64-bit
		* integer.
		*/
		public long getLong(Tag tag) {
		ByteBuffer b = ByteBuffer.wrap(get(tag));
		return b.getLong();
		}

		/**
		* Get the data associated with the given tag and decode it as a 32-bit
		* integer.
		*/
		public int getInt(Tag tag) {
		ByteBuffer b = ByteBuffer.wrap(get(tag));
		return b.getInt();
		}

		/**
		* Encode the given long value as a 64-bit little-endian value and
		* associate it with the given tag.
		*/
		public void putLong(Tag tag, long l) {
		ByteBuffer b = ByteBuffer.allocate(8);
		b.putLong(l);
		put(tag, b.array());
		}

		/**
		* Encode the given int value as a 32-bit little-endian value and
		* associate it with the given tag.
		*/
		public void putInt(Tag tag, int l) {
		ByteBuffer b = ByteBuffer.allocate(4);
		b.putInt(l);
		put(tag, b.array());
		}

		/**
		* Get a packed representation of this message suitable for the wire.
		*/
		public byte[] serialize() {
		if (items.size() == 0) {
		if (padSize > 4)
		return new byte[padSize];
		else
		return new byte[4];
		}

		int size = 0;

		ArrayList<Integer> offsets = new ArrayList<Integer>();
		ArrayList<Integer> tagList = new ArrayList<Integer>(items.keySet());
		Collections.sort(tagList);

		boolean first = true;
		for (int tag : tagList) {
		if (! first) {
		offsets.add(size);
		}

		first = false;
		size += items.get(tag).length;
		}

		ByteBuffer dataBuf = ByteBuffer.allocate(size);
		dataBuf.order(ByteOrder.LITTLE_ENDIAN);

		int valueDataSize = size;
		size += 4 + offsets.size() * 4 + tagList.size() * 4;

		int tagCount = items.size();

		if (size < padSize) {
		offsets.add(valueDataSize);
		tagList.add(Tag.PAD.value());

		if (size + 8 > padSize) {
		size = size + 8;
		} else {
		size = padSize;
		}

		tagCount += 1;
		}

		ByteBuffer buf = ByteBuffer.allocate(size);
		buf.order(ByteOrder.LITTLE_ENDIAN);
		buf.putInt(tagCount);

		for (int offset : offsets) {
		buf.putInt(offset);
		}

		for (int tag : tagList) {
		buf.putInt(tag);

		if (tag != Tag.PAD.value()) {
		dataBuf.put(items.get(tag));
		}
		}

		buf.put(dataBuf.array());

		return buf.array();
		}

		/**
		* Given a byte stream from the wire, unpack it into a Message object.
		*/
		public static Message deserialize(byte[] data) {
		ByteBuffer buf = ByteBuffer.wrap(data);
		buf.order(ByteOrder.LITTLE_ENDIAN);

		Message msg = new Message();

		int count = buf.getInt();

		if (count == 0) {
		return msg;
		}

		ArrayList<Integer> offsets = new ArrayList<Integer>();
		offsets.add(0);

		for (int i = 1; i < count; i++) {
		offsets.add(buf.getInt());
		}

		ArrayList<Integer> tags = new ArrayList<Integer>();
		for (int i = 0; i < count; i++) {
		int tag = buf.getInt();
		tags.add(tag);
		}

		offsets.add(buf.remaining());

		for (int i = 0; i < count; i++) {
		int tag = tags.get(i);
		int start = offsets.get(i);
		int end = offsets.get(i+1);
		byte[] content = new byte[end - start];

		buf.get(content);
		if (tag != Tag.PAD.value()) {
		msg.put(tag, content);
		}
		}

		return msg;
		}

		/**
		* Send this message over the given socket to the given address and port.
		*/
		public void send(DatagramSocket socket, InetAddress address, int port)
		throws IOException {
		byte[] buffer = serialize();
		DatagramPacket message = new DatagramPacket(buffer, buffer.length,
		address, port);
		socket.send(message);
		}

		/**
		* Receive a Message object from the given socket.
		*/
		public static Message receive(DatagramSocket socket)
		throws IOException {
		byte[] buffer = new byte[MAX_DATAGRAM_SIZE];
		DatagramPacket packet = new DatagramPacket(buffer, buffer.length);

		socket.receive(packet);

		return deserialize(Arrays.copyOf(buffer, packet.getLength()));
		}
		}

		private MessageDigest messageDigest = null;

		private final ArrayList<Result> results = new ArrayList<Result>();
		private long lastRequest = 0;

		private Message createRequestMessage() {
		byte[] nonce = new byte[NONCE_SIZE];
		random.nextBytes(nonce); // TODO: Chain nonces

		assert nonce.length == NONCE_SIZE :
		"Nonce must be " + NONCE_SIZE + " bytes.";

		Message msg = new Message();

		msg.put(Tag.NONC, nonce);
		msg.padSize = MIN_REQUEST_SIZE;

		return msg;
		}

		/**
		* Contact the Roughtime server at the given address and port and collect a
		* result time to add to our collection.
		*
		* @param host host name of the server.
		* @param timeout network timeout in milliseconds.
		* @return true if the transaction was successful.
		*/
		public boolean requestTime(String host, int timeout) {
		InetAddress address = null;
		try {
		address = InetAddress.getByName(host);
		} catch (Exception e) {
		if (ENABLE_DEBUG) {
		Log.d(TAG, "request time failed", e);
		}

		return false;
		}
		return requestTime(address, ROUGHTIME_PORT, timeout);
		}

		/**
		* Contact the Roughtime server at the given address and port and collect a
		* result time to add to our collection.
		*
		* @param address address for the server.
		* @param port port to talk to the server on.
		* @param timeout network timeout in milliseconds.
		* @return true if the transaction was successful.
		*/
		public boolean requestTime(InetAddress address, int port, int timeout) {

		final long rightNow = SystemClock.elapsedRealtime();

		if ((rightNow - lastRequest) > timeout) {
		results.clear();
		}

		lastRequest = rightNow;

		DatagramSocket socket = null;
		try {
		if (messageDigest == null) {
		messageDigest = MessageDigest.getInstance("SHA-512");
		}

		socket = new DatagramSocket();
		socket.setSoTimeout(timeout);
		final long startTime = SystemClock.elapsedRealtime();
		Message request = createRequestMessage();
		request.send(socket, address, port);
		final long endTime = SystemClock.elapsedRealtime();
		Message response = Message.receive(socket);
		byte[] signedData = response.get(Tag.SREP);
		Message signedResponse = Message.deserialize(signedData);

		final Result result = new Result();
		result.midpoint = signedResponse.getLong(Tag.MIDP);
		result.radius = signedResponse.getInt(Tag.RADI);
		result.collectionTime = (startTime + endTime) / 2;

		final byte[] root = signedResponse.get(Tag.ROOT);
		final byte[] path = response.get(Tag.PATH);
		final byte[] nonce = request.get(Tag.NONC);
		final int index = response.getInt(Tag.INDX);

		if (! verifyNonce(root, path, nonce, index)) {
		Log.w(TAG, "failed to authenticate roughtime response.");
		return false;
		}

		results.add(result);
		} catch (Exception e) {
		if (ENABLE_DEBUG) {
		Log.d(TAG, "request time failed", e);
		}

		return false;
		} finally {
		if (socket != null) {
		socket.close();
		}
		}

		return true;
		}

		/**
		* Verify that a reply message corresponds to the nonce sent in the request.
		*
		* @param root Root of the Merkle tree used to sign the nonce. Received in
		* the ROOT tag of the reply.
		* @param path Sibling hashes along the path to the root of the Merkle tree.
		* Received in the PATH tag of the reply.
		* @param nonce The nonce we sent in the request.
		* @param index Bitfield indicating whether chunks of the path are left or
		* right children.
		* @return true if the verification is successful.
		*/
		private boolean verifyNonce(byte[] root, byte[] path, byte[] nonce,
		int index) {
		messageDigest.update(new byte[]{ 0 });
		byte[] hash = messageDigest.digest(nonce);
		int pos = 0;
		byte[] one = new byte[]{ 1 };

		while (pos < path.length) {
		messageDigest.update(one);

		if ((index&1) != 0) {
		messageDigest.update(path, pos, 64);
		hash = messageDigest.digest(hash);
		} else {
		messageDigest.update(hash);
		messageDigest.update(path, pos, 64);
		hash = messageDigest.digest();
		}

		pos += 64;
		index >>>= 1;
		}

		return Arrays.equals(root, hash);
		}
		}

core/tests/coretests/src/android/net/RoughtimeClientTest.java

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		/*
		* Copyright (C) 2016 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;

		import android.net.RoughtimeClient;
		import android.util.Log;
		import libcore.util.HexEncoding;

		import java.io.IOException;
		import java.net.DatagramPacket;
		import java.net.DatagramSocket;
		import java.net.InetAddress;
		import java.net.SocketException;
		import java.security.MessageDigest;
		import java.util.Arrays;
		import junit.framework.TestCase;


		public class RoughtimeClientTest extends TestCase {
		private static final String TAG = "RoughtimeClientTest";

		private static final long TEST_TIME = 8675309;
		private static final int TEST_RADIUS = 42;

		private final RoughtimeTestServer mServer = new RoughtimeTestServer();
		private final RoughtimeClient mClient = new RoughtimeClient();

		public void testBasicWorkingRoughtimeClientQuery() throws Exception {
		mServer.shouldRespond(true);
		assertTrue(mClient.requestTime(mServer.getAddress(), mServer.getPort(), 500));
		assertEquals(1, mServer.numRequestsReceived());
		assertEquals(1, mServer.numRepliesSent());
		}

		public void testDnsResolutionFailure() throws Exception {
		mServer.shouldRespond(true);
		assertFalse(mClient.requestTime("roughtime.server.doesnotexist.example", 5000));
		}

		public void testTimeoutFailure() throws Exception {
		mServer.shouldRespond(false);
		assertFalse(mClient.requestTime(mServer.getAddress(), mServer.getPort(), 500));
		assertEquals(1, mServer.numRequestsReceived());
		assertEquals(0, mServer.numRepliesSent());
		}

		private static MessageDigest md = null;

		private static byte[] signedResponse(byte[] nonce) {
		RoughtimeClient.Message signed = new RoughtimeClient.Message();

		try {
		if (md == null) {
		md = MessageDigest.getInstance("SHA-512");
		}
		} catch(Exception e) {
		return null;
		}

		md.update(new byte[]{0});
		byte[] hash = md.digest(nonce);
		signed.put(RoughtimeClient.Tag.ROOT, hash);
		signed.putLong(RoughtimeClient.Tag.MIDP, TEST_TIME);
		signed.putInt(RoughtimeClient.Tag.RADI, TEST_RADIUS);

		return signed.serialize();
		}

		private static byte[] response(byte[] nonce) {
		RoughtimeClient.Message msg = new RoughtimeClient.Message();

		msg.put(RoughtimeClient.Tag.SREP, signedResponse(nonce));
		msg.putInt(RoughtimeClient.Tag.INDX, 0);
		msg.put(RoughtimeClient.Tag.PATH, new byte[0]);

		return msg.serialize();
		}

		private static class RoughtimeTestServer {
		private final Object mLock = new Object();
		private final DatagramSocket mSocket;
		private final InetAddress mAddress;
		private final int mPort;
		private int mRcvd;
		private int mSent;
		private Thread mListeningThread;
		private boolean mShouldRespond = true;

		public RoughtimeTestServer() {
		mSocket = makeSocket();
		mAddress = mSocket.getLocalAddress();
		mPort = mSocket.getLocalPort();
		Log.d(TAG, "testing server listening on (" + mAddress + ", " + mPort + ")");

		mListeningThread = new Thread() {
		public void run() {
		while (true) {
		byte[] buffer = new byte[2048];
		DatagramPacket request = new DatagramPacket(buffer, buffer.length);
		try {
		mSocket.receive(request);
		} catch (IOException e) {
		Log.e(TAG, "datagram receive error: " + e);
		break;
		}
		synchronized (mLock) {
		mRcvd++;

		if (! mShouldRespond) {
		continue;
		}

		RoughtimeClient.Message msg =
		RoughtimeClient.Message.deserialize(
		Arrays.copyOf(buffer, request.getLength()));

		byte[] nonce = msg.get(RoughtimeClient.Tag.NONC);
		if (nonce.length != 64) {
		Log.e(TAG, "Nonce is wrong length.");
		}

		try {
		request.setData(response(nonce));
		mSocket.send(request);
		} catch (IOException e) {
		Log.e(TAG, "datagram send error: " + e);
		break;
		}
		mSent++;
		}
		}
		mSocket.close();
		}
		};
		mListeningThread.start();
		}

		private DatagramSocket makeSocket() {
		DatagramSocket socket;
		try {
		socket = new DatagramSocket(0, InetAddress.getLoopbackAddress());
		} catch (SocketException e) {
		Log.e(TAG, "Failed to create test server socket: " + e);
		return null;
		}
		return socket;
		}

		public void shouldRespond(boolean value) { mShouldRespond = value; }

		public InetAddress getAddress() { return mAddress; }
		public int getPort() { return mPort; }
		public int numRequestsReceived() { synchronized (mLock) { return mRcvd; } }
		public int numRepliesSent() { synchronized (mLock) { return mSent; } }
		}
		}