/* * Copyright (C) 2015 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.util; import android.net.util.IpUtils; import android.test.suitebuilder.annotation.SmallTest; import java.nio.ByteBuffer; import junit.framework.TestCase; public class IpUtilsTest extends TestCase { private static final int IPV4_HEADER_LENGTH = 20; private static final int IPV6_HEADER_LENGTH = 40; private static final int TCP_HEADER_LENGTH = 20; private static final int UDP_HEADER_LENGTH = 8; private static final int IP_CHECKSUM_OFFSET = 10; private static final int TCP_CHECKSUM_OFFSET = 16; private static final int UDP_CHECKSUM_OFFSET = 6; private int getUnsignedByte(ByteBuffer buf, int offset) { return buf.get(offset) & 0xff; } private int getChecksum(ByteBuffer buf, int offset) { return getUnsignedByte(buf, offset) * 256 + getUnsignedByte(buf, offset + 1); } private void assertChecksumEquals(int expected, short actual) { assertEquals(Integer.toHexString(expected), Integer.toHexString(actual & 0xffff)); } // Generate test packets using Python code like this:: // // from scapy import all as scapy // // def JavaPacketDefinition(bytes): // out = " ByteBuffer packet = ByteBuffer.wrap(new byte[] {\n " // for i in xrange(len(bytes)): // out += "(byte) 0x%02x" % ord(bytes[i]) // if i < len(bytes) - 1: // if i % 4 == 3: // out += ",\n " // else: // out += ", " // out += "\n });" // return out // // packet = (scapy.IPv6(src="2001:db8::1", dst="2001:db8::2") / // scapy.UDP(sport=12345, dport=7) / // "hello") // print JavaPacketDefinition(str(packet)) @SmallTest public void testIpv6TcpChecksum() throws Exception { // packet = (scapy.IPv6(src="2001:db8::1", dst="2001:db8::2", tc=0x80) / // scapy.TCP(sport=12345, dport=7, // seq=1692871236, ack=128376451, flags=16, // window=32768) / // "hello, world") ByteBuffer packet = ByteBuffer.wrap(new byte[] { (byte) 0x68, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x20, (byte) 0x06, (byte) 0x40, (byte) 0x20, (byte) 0x01, (byte) 0x0d, (byte) 0xb8, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x01, (byte) 0x20, (byte) 0x01, (byte) 0x0d, (byte) 0xb8, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x02, (byte) 0x30, (byte) 0x39, (byte) 0x00, (byte) 0x07, (byte) 0x64, (byte) 0xe7, (byte) 0x2a, (byte) 0x44, (byte) 0x07, (byte) 0xa6, (byte) 0xde, (byte) 0x83, (byte) 0x50, (byte) 0x10, (byte) 0x80, (byte) 0x00, (byte) 0xee, (byte) 0x71, (byte) 0x00, (byte) 0x00, (byte) 0x68, (byte) 0x65, (byte) 0x6c, (byte) 0x6c, (byte) 0x6f, (byte) 0x2c, (byte) 0x20, (byte) 0x77, (byte) 0x6f, (byte) 0x72, (byte) 0x6c, (byte) 0x64 }); // Check that a valid packet has checksum 0. int transportLen = packet.limit() - IPV6_HEADER_LENGTH; assertEquals(0, IpUtils.tcpChecksum(packet, 0, IPV6_HEADER_LENGTH, transportLen)); // Check that we can calculate the checksum from scratch. int sumOffset = IPV6_HEADER_LENGTH + TCP_CHECKSUM_OFFSET; int sum = getUnsignedByte(packet, sumOffset) * 256 + getUnsignedByte(packet, sumOffset + 1); assertEquals(0xee71, sum); packet.put(sumOffset, (byte) 0); packet.put(sumOffset + 1, (byte) 0); assertChecksumEquals(sum, IpUtils.tcpChecksum(packet, 0, IPV6_HEADER_LENGTH, transportLen)); // Check that writing the checksum back into the packet results in a valid packet. packet.putShort( sumOffset, IpUtils.tcpChecksum(packet, 0, IPV6_HEADER_LENGTH, transportLen)); assertEquals(0, IpUtils.tcpChecksum(packet, 0, IPV6_HEADER_LENGTH, transportLen)); } @SmallTest public void testIpv4UdpChecksum() { // packet = (scapy.IP(src="192.0.2.1", dst="192.0.2.2", tos=0x40) / // scapy.UDP(sport=32012, dport=4500) / // "\xff") ByteBuffer packet = ByteBuffer.wrap(new byte[] { (byte) 0x45, (byte) 0x40, (byte) 0x00, (byte) 0x1d, (byte) 0x00, (byte) 0x01, (byte) 0x00, (byte) 0x00, (byte) 0x40, (byte) 0x11, (byte) 0xf6, (byte) 0x8b, (byte) 0xc0, (byte) 0x00, (byte) 0x02, (byte) 0x01, (byte) 0xc0, (byte) 0x00, (byte) 0x02, (byte) 0x02, (byte) 0x7d, (byte) 0x0c, (byte) 0x11, (byte) 0x94, (byte) 0x00, (byte) 0x09, (byte) 0xee, (byte) 0x36, (byte) 0xff }); // Check that a valid packet has IP checksum 0 and UDP checksum 0xffff (0 is not a valid // UDP checksum, so the udpChecksum rewrites 0 to 0xffff). assertEquals(0, IpUtils.ipChecksum(packet, 0)); assertEquals((short) 0xffff, IpUtils.udpChecksum(packet, 0, IPV4_HEADER_LENGTH)); // Check that we can calculate the checksums from scratch. final int ipSumOffset = IP_CHECKSUM_OFFSET; final int ipSum = getChecksum(packet, ipSumOffset); assertEquals(0xf68b, ipSum); packet.put(ipSumOffset, (byte) 0); packet.put(ipSumOffset + 1, (byte) 0); assertChecksumEquals(ipSum, IpUtils.ipChecksum(packet, 0)); final int udpSumOffset = IPV4_HEADER_LENGTH + UDP_CHECKSUM_OFFSET; final int udpSum = getChecksum(packet, udpSumOffset); assertEquals(0xee36, udpSum); packet.put(udpSumOffset, (byte) 0); packet.put(udpSumOffset + 1, (byte) 0); assertChecksumEquals(udpSum, IpUtils.udpChecksum(packet, 0, IPV4_HEADER_LENGTH)); // Check that writing the checksums back into the packet results in a valid packet. packet.putShort(ipSumOffset, IpUtils.ipChecksum(packet, 0)); packet.putShort(udpSumOffset, IpUtils.udpChecksum(packet, 0, IPV4_HEADER_LENGTH)); assertEquals(0, IpUtils.ipChecksum(packet, 0)); assertEquals((short) 0xffff, IpUtils.udpChecksum(packet, 0, IPV4_HEADER_LENGTH)); } }