Add utilities to filter packet am: c416cfb452 am: 1a5686e0c9 am: 146e210009 am: 7add194994 (6a37c0b4) · Commits · e / os / android_packages_modules_NetworkStack

tests/lib/multivariant/com/android/testutils/PacketFilter.kt

0 → 100644

+87 −0

Original line number	Original line	Diff line number	Diff line
			/*
			* 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 com.android.testutils

			import java.util.function.Predicate

			const val ETHER_TYPE_OFFSET = 12
			const val ETHER_HEADER_LENGTH = 14
			const val IPV4_PROTOCOL_OFFSET = ETHER_HEADER_LENGTH + 9
			const val IPV4_CHECKSUM_OFFSET = ETHER_HEADER_LENGTH + 10
			const val IPV4_HEADER_LENGTH = 20
			const val IPV4_UDP_OFFSET = ETHER_HEADER_LENGTH + IPV4_HEADER_LENGTH
			const val BOOTP_OFFSET = IPV4_UDP_OFFSET + 8
			const val BOOTP_TID_OFFSET = BOOTP_OFFSET + 4
			const val BOOTP_CLIENT_MAC_OFFSET = BOOTP_OFFSET + 28
			const val DHCP_OPTIONS_OFFSET = BOOTP_OFFSET + 240

			/**
			* A [Predicate] that matches a [ByteArray] if it contains the specified [bytes] at the specified
			* [offset].
			*/
			class OffsetFilter(val offset: Int, vararg val bytes: Byte) : Predicate<ByteArray> {
			override fun test(packet: ByteArray) =
			bytes.withIndex().all { it.value == packet[offset + it.index] }
			}

			/**
			* A [Predicate] that matches ethernet-encapped packets that contain an UDP over IPv4 datagram.
			*/
			class IPv4UdpFilter : Predicate<ByteArray> {
			private val impl = OffsetFilter(ETHER_TYPE_OFFSET, 0x08, 0x00 /* IPv4 */).and(
			OffsetFilter(IPV4_PROTOCOL_OFFSET, 17 /* UDP */))
			override fun test(t: ByteArray) = impl.test(t)
			}

			/**
			* A [Predicate] that matches ethernet-encapped DHCP packets sent from a DHCP client.
			*/
			class DhcpClientPacketFilter : Predicate<ByteArray> {
			private val impl = IPv4UdpFilter()
			.and(OffsetFilter(IPV4_UDP_OFFSET /* source port /, 0x00, 0x44 / 68 */))
			.and(OffsetFilter(IPV4_UDP_OFFSET + 2 /* dest port /, 0x00, 0x43 / 67 */))
			override fun test(t: ByteArray) = impl.test(t)
			}

			/**
			* A [Predicate] that matches a [ByteArray] if it contains a ethernet-encapped DHCP packet that
			* contains the specified option with the specified [bytes] as value.
			*/
			class DhcpOptionFilter(val option: Byte, vararg val bytes: Byte) : Predicate<ByteArray> {
			override fun test(packet: ByteArray): Boolean {
			val option = findDhcpOption(packet, option) ?: return false
			return option.contentEquals(bytes)
			}
			}

			/**
			* Find a DHCP option in a packet and return its value, if found.
			*/
			fun findDhcpOption(packet: ByteArray, option: Byte): ByteArray? =
			findOptionOffset(packet, option, DHCP_OPTIONS_OFFSET)?.let {
			val optionLen = packet[it + 1]
			return packet.copyOfRange(it + 2 /* type, length bytes */, it + 2 + optionLen)
			}

			private tailrec fun findOptionOffset(packet: ByteArray, option: Byte, searchOffset: Int): Int? {
			if (packet.size <= searchOffset + 2 /* type, length bytes */) return null

			return if (packet[searchOffset] == option) searchOffset else {
			val optionLen = packet[searchOffset + 1]
			findOptionOffset(packet, option, searchOffset + 2 + optionLen)
			}
			}

tests/lib/src/com/android/testutils/TapPacketReader.java

+18 −11

Original line number	Original line	Diff line number	Diff line
	@@ -19,6 +19,7 @@ package com.android.testutils;
	import android.net.util.PacketReader;		import android.net.util.PacketReader;
	import android.os.Handler;		import android.os.Handler;

			import androidx.annotation.NonNull;
	import androidx.annotation.Nullable;		import androidx.annotation.Nullable;

	import java.io.FileDescriptor;		import java.io.FileDescriptor;
	@@ -26,12 +27,16 @@ import java.io.FileOutputStream;
	import java.io.IOException;		import java.io.IOException;
	import java.nio.ByteBuffer;		import java.nio.ByteBuffer;
	import java.util.Arrays;		import java.util.Arrays;
	import java.util.concurrent.LinkedBlockingQueue;		import java.util.function.Predicate;
	import java.util.concurrent.TimeUnit;
			import kotlin.Lazy;
			import kotlin.LazyKt;

	public class TapPacketReader extends PacketReader {		public class TapPacketReader extends PacketReader {
	private final FileDescriptor mTapFd;		private final FileDescriptor mTapFd;
	private final LinkedBlockingQueue<byte[]> mReceivedPackets = new LinkedBlockingQueue<byte[]>();		private final ArrayTrackRecord<byte[]> mReceivedPackets = new ArrayTrackRecord<>();
			private final Lazy<ArrayTrackRecord<byte[]>.ReadHead> mReadHead =
			LazyKt.lazy(mReceivedPackets::newReadHead);

	public TapPacketReader(Handler h, FileDescriptor tapFd, int maxPacketSize) {		public TapPacketReader(Handler h, FileDescriptor tapFd, int maxPacketSize) {
	super(h, maxPacketSize);		super(h, maxPacketSize);
	@@ -46,23 +51,25 @@ public class TapPacketReader extends PacketReader {
	@Override		@Override
	protected void handlePacket(byte[] recvbuf, int length) {		protected void handlePacket(byte[] recvbuf, int length) {
	final byte[] newPacket = Arrays.copyOf(recvbuf, length);		final byte[] newPacket = Arrays.copyOf(recvbuf, length);
	if (!mReceivedPackets.offer(newPacket)) {		if (!mReceivedPackets.add(newPacket)) {
	throw new AssertionError("More than " + Integer.MAX_VALUE + " packets outstanding!");		throw new AssertionError("More than " + Integer.MAX_VALUE + " packets outstanding!");
	}		}
	}		}

	/**		/**
	* Get the next packet that was received on the interface.		* Get the next packet that was received on the interface.
	*
	*/		*/
	@Nullable		@Nullable
	public byte[] popPacket(long timeoutMs) {		public byte[] popPacket(long timeoutMs) {
	try {		return mReadHead.getValue().poll(timeoutMs, packet -> true);
	return mReceivedPackets.poll(timeoutMs, TimeUnit.MILLISECONDS);
	} catch (InterruptedException e) {
	// Fall through
	}		}
	return null;
			/**
			* Get the next packet that was received on the interface and matches the specified filter.
			*/
			@Nullable
			public byte[] popPacket(long timeoutMs, @NonNull Predicate<byte[]> filter) {
			return mReadHead.getValue().poll(timeoutMs, filter::test);
	}		}

	public void sendResponse(final ByteBuffer packet) throws IOException {		public void sendResponse(final ByteBuffer packet) throws IOException {