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/*
* Copyright (C) 2021 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.net.module.util;
import static android.system.OsConstants.IPPROTO_ICMPV6;
import static com.android.net.module.util.IpUtils.icmpv6Checksum;
import static com.android.net.module.util.NetworkStackConstants.ETHER_TYPE_IPV6;
import static com.android.net.module.util.NetworkStackConstants.ICMPV6_ECHO_REPLY_TYPE;
import static com.android.net.module.util.NetworkStackConstants.ICMPV6_ECHO_REQUEST_TYPE;
import static com.android.net.module.util.NetworkStackConstants.ICMPV6_NEIGHBOR_ADVERTISEMENT;
import static com.android.net.module.util.NetworkStackConstants.ICMPV6_NEIGHBOR_SOLICITATION;
import static com.android.net.module.util.NetworkStackConstants.ICMPV6_ROUTER_ADVERTISEMENT;
import static com.android.net.module.util.NetworkStackConstants.ICMPV6_ROUTER_SOLICITATION;
import android.net.MacAddress;
import com.android.net.module.util.structs.EthernetHeader;
import com.android.net.module.util.structs.Icmpv6Header;
import com.android.net.module.util.structs.Ipv6Header;
import com.android.net.module.util.structs.NaHeader;
import com.android.net.module.util.structs.NsHeader;
import com.android.net.module.util.structs.RaHeader;
import com.android.net.module.util.structs.RsHeader;
import java.net.Inet6Address;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
/**
* Utilities for IPv6 packets.
*/
public class Ipv6Utils {
/**
* Build a generic ICMPv6 packet without Ethernet header.
*/
public static ByteBuffer buildIcmpv6Packet(final Inet6Address srcIp, final Inet6Address dstIp,
short type, short code, final ByteBuffer... options) {
final int ipv6HeaderLen = Struct.getSize(Ipv6Header.class);
final int icmpv6HeaderLen = Struct.getSize(Icmpv6Header.class);
int payloadLen = 0;
for (ByteBuffer option: options) {
payloadLen += option.limit();
}
final ByteBuffer packet = ByteBuffer.allocate(ipv6HeaderLen + icmpv6HeaderLen + payloadLen);
final Ipv6Header ipv6Header =
new Ipv6Header((int) 0x60000000 /* version, traffic class, flowlabel */,
icmpv6HeaderLen + payloadLen /* payload length */,
(byte) IPPROTO_ICMPV6 /* next header */, (byte) 0xff /* hop limit */, srcIp, dstIp);
final Icmpv6Header icmpv6Header = new Icmpv6Header(type, code, (short) 0 /* checksum */);
ipv6Header.writeToByteBuffer(packet);
icmpv6Header.writeToByteBuffer(packet);
for (ByteBuffer option : options) {
packet.put(option);
// in case option might be reused by caller, restore the position and
// limit of bytebuffer.
option.clear();
}
packet.flip();
// Populate the ICMPv6 checksum field.
packet.putShort(ipv6HeaderLen + 2, icmpv6Checksum(packet, 0 /* ipOffset */,
ipv6HeaderLen /* transportOffset */,
(short) (icmpv6HeaderLen + payloadLen) /* transportLen */));
return packet;
}
/**
* Build a generic ICMPv6 packet(e.g., packet used in the neighbor discovery protocol).
*/
public static ByteBuffer buildIcmpv6Packet(final MacAddress srcMac, final MacAddress dstMac,
final Inet6Address srcIp, final Inet6Address dstIp, short type, short code,
final ByteBuffer... options) {
final ByteBuffer payload = buildIcmpv6Packet(srcIp, dstIp, type, code, options);
final int etherHeaderLen = Struct.getSize(EthernetHeader.class);
final ByteBuffer packet = ByteBuffer.allocate(etherHeaderLen + payload.limit());
final EthernetHeader ethHeader =
new EthernetHeader(dstMac, srcMac, (short) ETHER_TYPE_IPV6);
ethHeader.writeToByteBuffer(packet);
packet.put(payload);
packet.flip();
return packet;
}
/**
* Build the ICMPv6 packet payload including payload header and specific options.
*/
private static ByteBuffer[] buildIcmpv6Payload(final ByteBuffer payloadHeader,
final ByteBuffer... options) {
final ByteBuffer[] payload = new ByteBuffer[options.length + 1];
payload[0] = payloadHeader;
System.arraycopy(options, 0, payload, 1, options.length);
return payload;
}
/**
* Build an ICMPv6 Router Advertisement packet from the required specified parameters.
*/
public static ByteBuffer buildRaPacket(final MacAddress srcMac, final MacAddress dstMac,
final Inet6Address srcIp, final Inet6Address dstIp, final byte flags,
final int lifetime, final long reachableTime, final long retransTimer,
final ByteBuffer... options) {
final RaHeader raHeader = new RaHeader((byte) 0 /* hopLimit, unspecified */,
flags, lifetime, reachableTime, retransTimer);
final ByteBuffer[] payload = buildIcmpv6Payload(
ByteBuffer.wrap(raHeader.writeToBytes(ByteOrder.BIG_ENDIAN)), options);
return buildIcmpv6Packet(srcMac, dstMac, srcIp, dstIp,
(byte) ICMPV6_ROUTER_ADVERTISEMENT /* type */, (byte) 0 /* code */, payload);
}
/**
* Build an ICMPv6 Neighbor Advertisement packet from the required specified parameters.
*/
public static ByteBuffer buildNaPacket(final MacAddress srcMac, final MacAddress dstMac,
final Inet6Address srcIp, final Inet6Address dstIp, final int flags,
final Inet6Address target, final ByteBuffer... options) {
final NaHeader naHeader = new NaHeader(flags, target);
final ByteBuffer[] payload = buildIcmpv6Payload(
ByteBuffer.wrap(naHeader.writeToBytes(ByteOrder.BIG_ENDIAN)), options);
return buildIcmpv6Packet(srcMac, dstMac, srcIp, dstIp,
(byte) ICMPV6_NEIGHBOR_ADVERTISEMENT /* type */, (byte) 0 /* code */, payload);
}
/**
* Build an ICMPv6 Neighbor Solicitation packet from the required specified parameters.
*/
public static ByteBuffer buildNsPacket(final MacAddress srcMac, final MacAddress dstMac,
final Inet6Address srcIp, final Inet6Address dstIp,
final Inet6Address target, final ByteBuffer... options) {
final NsHeader nsHeader = new NsHeader(target);
final ByteBuffer[] payload = buildIcmpv6Payload(
ByteBuffer.wrap(nsHeader.writeToBytes(ByteOrder.BIG_ENDIAN)), options);
return buildIcmpv6Packet(srcMac, dstMac, srcIp, dstIp,
(byte) ICMPV6_NEIGHBOR_SOLICITATION /* type */, (byte) 0 /* code */, payload);
}
/**
* Build an ICMPv6 Router Solicitation packet from the required specified parameters.
*/
public static ByteBuffer buildRsPacket(final MacAddress srcMac, final MacAddress dstMac,
final Inet6Address srcIp, final Inet6Address dstIp, final ByteBuffer... options) {
final RsHeader rsHeader = new RsHeader((int) 0 /* reserved */);
final ByteBuffer[] payload = buildIcmpv6Payload(
ByteBuffer.wrap(rsHeader.writeToBytes(ByteOrder.BIG_ENDIAN)), options);
return buildIcmpv6Packet(srcMac, dstMac, srcIp, dstIp,
(byte) ICMPV6_ROUTER_SOLICITATION /* type */, (byte) 0 /* code */, payload);
}
/**
* Build an ICMPv6 Echo Request packet from the required specified parameters.
*/
public static ByteBuffer buildEchoRequestPacket(final MacAddress srcMac,
final MacAddress dstMac, final Inet6Address srcIp, final Inet6Address dstIp) {
final ByteBuffer payload = ByteBuffer.allocate(4); // ID and Sequence number may be zero.
return buildIcmpv6Packet(srcMac, dstMac, srcIp, dstIp,
(byte) ICMPV6_ECHO_REQUEST_TYPE /* type */, (byte) 0 /* code */, payload);
}
/**
* Build an ICMPv6 Echo Reply packet without ethernet header.
*/
public static ByteBuffer buildEchoReplyPacket(final Inet6Address srcIp,
final Inet6Address dstIp) {
final ByteBuffer payload = ByteBuffer.allocate(4); // ID and Sequence number may be zero.
return buildIcmpv6Packet(srcIp, dstIp, (byte) ICMPV6_ECHO_REPLY_TYPE /* type */,
(byte) 0 /* code */, payload);
}
}
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