/*
 * Copyright (C) 2018 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.server.util;

import static com.android.net.module.util.Inet4AddressUtils.intToInet4AddressHTH;

import java.net.Inet4Address;

/**
 * Network constants used by the network stack.
 */
public final class NetworkStackConstants {

    /**
     * Ethernet constants.
     *
     * See also:
     *     - https://tools.ietf.org/html/rfc894
     *     - https://tools.ietf.org/html/rfc2464
     *     - https://tools.ietf.org/html/rfc7042
     *     - http://www.iana.org/assignments/ethernet-numbers/ethernet-numbers.xhtml
     *     - http://www.iana.org/assignments/ieee-802-numbers/ieee-802-numbers.xhtml
     */
    public static final int ETHER_DST_ADDR_OFFSET = 0;
    public static final int ETHER_SRC_ADDR_OFFSET = 6;
    public static final int ETHER_ADDR_LEN = 6;
    public static final int ETHER_TYPE_OFFSET = 12;
    public static final int ETHER_TYPE_LENGTH = 2;
    public static final int ETHER_TYPE_ARP  = 0x0806;
    public static final int ETHER_TYPE_IPV4 = 0x0800;
    public static final int ETHER_TYPE_IPV6 = 0x86dd;
    public static final int ETHER_HEADER_LEN = 14;
    public static final int ETHER_MTU = 1500;

    /**
     * ARP constants.
     *
     * See also:
     *     - https://tools.ietf.org/html/rfc826
     *     - http://www.iana.org/assignments/arp-parameters/arp-parameters.xhtml
     */
    public static final int ARP_PAYLOAD_LEN = 28;  // For Ethernet+IPv4.
    public static final int ARP_ETHER_IPV4_LEN = ARP_PAYLOAD_LEN + ETHER_HEADER_LEN;
    public static final int ARP_REQUEST = 1;
    public static final int ARP_REPLY   = 2;
    public static final int ARP_HWTYPE_RESERVED_LO = 0;
    public static final int ARP_HWTYPE_ETHER       = 1;
    public static final int ARP_HWTYPE_RESERVED_HI = 0xffff;

    /**
     * IPv4 Address Conflict Detection constants.
     *
     * See also:
     *     - https://tools.ietf.org/html/rfc5227
     */
    public static final int IPV4_CONFLICT_PROBE_NUM = 3;
    public static final int IPV4_CONFLICT_ANNOUNCE_NUM = 2;

    /**
     * IPv4 constants.
     *
     * See also:
     *     - https://tools.ietf.org/html/rfc791
     */
    public static final int IPV4_ADDR_BITS = 32;
    public static final int IPV4_MIN_MTU = 68;
    public static final int IPV4_MAX_MTU = 65_535;
    public static final int IPV4_HEADER_MIN_LEN = 20;
    public static final int IPV4_IHL_MASK = 0xf;
    public static final int IPV4_FLAGS_OFFSET = 6;
    public static final int IPV4_FRAGMENT_MASK = 0x1fff;
    public static final int IPV4_PROTOCOL_OFFSET = 9;
    public static final int IPV4_SRC_ADDR_OFFSET = 12;
    public static final int IPV4_DST_ADDR_OFFSET = 16;
    public static final int IPV4_ADDR_LEN = 4;
    public static final Inet4Address IPV4_ADDR_ALL = intToInet4AddressHTH(0xffffffff);
    public static final Inet4Address IPV4_ADDR_ANY = intToInet4AddressHTH(0x0);

    /**
     * IPv6 constants.
     *
     * See also:
     *     - https://tools.ietf.org/html/rfc2460
     */
    public static final int IPV6_ADDR_LEN = 16;
    public static final int IPV6_HEADER_LEN = 40;
    public static final int IPV6_LEN_OFFSET = 4;
    public static final int IPV6_PROTOCOL_OFFSET = 6;
    public static final int IPV6_SRC_ADDR_OFFSET = 8;
    public static final int IPV6_DST_ADDR_OFFSET = 24;
    public static final int IPV6_MIN_MTU = 1280;

    /**
     * ICMPv6 constants.
     *
     * See also:
     *     - https://tools.ietf.org/html/rfc4443
     *     - https://tools.ietf.org/html/rfc4861
     */
    public static final int ICMPV6_HEADER_MIN_LEN = 4;
    public static final int ICMPV6_CHECKSUM_OFFSET = 2;
    public static final int ICMPV6_ECHO_REPLY_TYPE = 129;
    public static final int ICMPV6_ECHO_REQUEST_TYPE = 128;
    public static final int ICMPV6_ROUTER_SOLICITATION    = 133;
    public static final int ICMPV6_ROUTER_ADVERTISEMENT   = 134;
    public static final int ICMPV6_NEIGHBOR_SOLICITATION  = 135;
    public static final int ICMPV6_NEIGHBOR_ADVERTISEMENT = 136;
    public static final int ICMPV6_ND_OPTION_MIN_LENGTH = 8;
    public static final int ICMPV6_ND_OPTION_LENGTH_SCALING_FACTOR = 8;
    public static final int ICMPV6_ND_OPTION_SLLA  = 1;
    public static final int ICMPV6_ND_OPTION_TLLA  = 2;
    public static final int ICMPV6_ND_OPTION_PIO   = 3;
    public static final int ICMPV6_ND_OPTION_MTU   = 5;
    public static final int ICMPV6_ND_OPTION_RDNSS = 25;
    public static final int ICMPV6_ND_OPTION_PREF64 = 38;


    public static final int ICMPV6_RA_HEADER_LEN = 16;

    /**
     * UDP constants.
     *
     * See also:
     *     - https://tools.ietf.org/html/rfc768
     */
    public static final int UDP_HEADER_LEN = 8;


    /**
     * DHCP constants.
     *
     * See also:
     *     - https://tools.ietf.org/html/rfc2131
     */
    public static final int INFINITE_LEASE = 0xffffffff;
    public static final int DHCP4_CLIENT_PORT = 68;

    /**
     * IEEE802.11 standard constants.
     *
     * See also:
     *     - https://ieeexplore.ieee.org/document/7786995
     */
    public static final int VENDOR_SPECIFIC_IE_ID = 0xdd;

    private NetworkStackConstants() {
        throw new UnsupportedOperationException("This class is not to be instantiated");
    }
}