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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.structs;
import static com.android.net.module.util.NetworkStackConstants.ICMPV6_ND_OPTION_RDNSS;
import android.net.InetAddresses;
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.net.Inet6Address;
import java.nio.ByteBuffer;
/**
* IPv6 RA recursive DNS server option, as per https://tools.ietf.org/html/rfc8106.
* This should be followed by a series of DNSv6 server addresses.
*
* 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 | Reserved |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Lifetime |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* : Addresses of IPv6 Recursive DNS Servers :
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
public class RdnssOption extends Struct {
@Field(order = 0, type = Type.S8)
public final byte type;
@Field(order = 1, type = Type.S8)
public final byte length; // Length in 8-byte units
@Field(order = 2, type = Type.S16)
public final short reserved;
@Field(order = 3, type = Type.U32)
public final long lifetime;
public RdnssOption(final byte type, final byte length, final short reserved,
final long lifetime) {
this.type = type;
this.length = length;
this.reserved = reserved;
this.lifetime = lifetime;
}
/**
* Build a RDNSS option from the required specified Inet6Address parameters.
*/
public static ByteBuffer build(final long lifetime, final Inet6Address... servers) {
final byte length = (byte) (1 + 2 * servers.length);
final RdnssOption option = new RdnssOption((byte) ICMPV6_ND_OPTION_RDNSS,
length, (short) 0, lifetime);
final ByteBuffer buffer = ByteBuffer.allocate(length * 8);
option.writeToByteBuffer(buffer);
for (Inet6Address server : servers) {
buffer.put(server.getAddress());
}
buffer.flip();
return buffer;
}
/**
* Build a RDNSS option from the required specified String parameters.
*
* @throws IllegalArgumentException if {@code servers} does not contain only numeric addresses.
*/
public static ByteBuffer build(final long lifetime, final String... servers) {
final Inet6Address[] serverArray = new Inet6Address[servers.length];
for (int i = 0; i < servers.length; i++) {
serverArray[i] = (Inet6Address) InetAddresses.parseNumericAddress(servers[i]);
}
return build(lifetime, serverArray);
}
}
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