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/*
* Copyright (C) 2023 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.structs;
import static com.android.net.module.util.NetworkStackConstants.ICMPV6_ND_OPTION_RIO;
import android.net.IpPrefix;
import androidx.annotation.NonNull;
import com.android.net.module.util.Struct;
import com.android.net.module.util.Struct.Field;
import com.android.net.module.util.Struct.Type;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
/**
* ICMPv6 route information option, as per https://tools.ietf.org/html/rfc4191.
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Type | Length | Prefix Length |Resvd|Prf|Resvd|
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Route Lifetime |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Prefix (Variable Length) |
* . .
* . .
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
public class RouteInformationOption extends Struct {
public enum Preference {
HIGH((byte) 0x1),
MEDIUM((byte) 0x0),
LOW((byte) 0x3),
RESERVED((byte) 0x2);
final byte mValue;
Preference(byte value) {
this.mValue = value;
}
}
@Field(order = 0, type = Type.S8)
public final byte type;
@Field(order = 1, type = Type.S8)
public final byte length; // Length in 8-byte octets
@Field(order = 2, type = Type.U8)
public final short prefixLen;
@Field(order = 3, type = Type.S8)
public final byte prf;
@Field(order = 4, type = Type.U32)
public final long routeLifetime;
@Field(order = 5, type = Type.ByteArray, arraysize = 16)
public final byte[] prefix;
RouteInformationOption(final byte type, final byte length, final short prefixLen,
final byte prf, final long routeLifetime, @NonNull final byte[] prefix) {
this.type = type;
this.length = length;
this.prefixLen = prefixLen;
this.prf = prf;
this.routeLifetime = routeLifetime;
this.prefix = prefix;
}
/**
* Build a Route Information option from the required specified parameters.
*/
public static ByteBuffer build(final IpPrefix prefix, final Preference prf,
final long routeLifetime) {
// The prefix field is always assumed to have 16 bytes, but the number of leading
// bits in this prefix depends on IpPrefix#prefixLength, then we can simply set the
// option length to 3.
final RouteInformationOption option = new RouteInformationOption(
(byte) ICMPV6_ND_OPTION_RIO, (byte) 3 /* option length */,
(short) prefix.getPrefixLength(), (byte) (prf.mValue << 3), routeLifetime,
prefix.getRawAddress());
return ByteBuffer.wrap(option.writeToBytes(ByteOrder.BIG_ENDIAN));
}
}
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