package org.dynmap.utils;
/*
 * Copyright 2002-2019 the original author or authors.
 *
 * 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
 *
 *      https://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.
 */

import java.net.InetAddress;
import java.net.UnknownHostException;

/**
 * Matches a request based on IP Address or subnet mask matching against the remote
 * address.
 * <p>
 * Both IPv6 and IPv4 addresses are supported, but a matcher which is configured with an
 * IPv4 address will never match a request which returns an IPv6 address, and vice-versa.
 *
 * @author Luke Taylor
 * @since 3.0.2
 * 
 * Slightly modified by omidzk to have zero dependency to any frameworks other than the JRE.
 */
public final class IpAddressMatcher {
    private final int nMaskBits;
    private final InetAddress requiredAddress;

    /**
     * Takes a specific IP address or a range specified using the IP/Netmask (e.g.
     * 192.168.1.0/24 or 202.24.0.0/14).
     *
     * @param ipAddress the address or range of addresses from which the request must
     * come.
     */
    public IpAddressMatcher(String ipAddress) {

        if (ipAddress.indexOf('/') > 0) {
            String[] addressAndMask = ipAddress.split("/");
            ipAddress = addressAndMask[0];
            nMaskBits = Integer.parseInt(addressAndMask[1]);
        }
        else {
            nMaskBits = -1;
        }
        requiredAddress = parseAddress(ipAddress);
        assert  (requiredAddress.getAddress().length * 8 >= nMaskBits) :
                String.format("IP address %s is too short for bitmask of length %d",
                        ipAddress, nMaskBits);
    }

    public boolean matches(String address) {
        InetAddress remoteAddress = parseAddress(address);

        if (!requiredAddress.getClass().equals(remoteAddress.getClass())) {
            return false;
        }

        if (nMaskBits < 0) {
            return remoteAddress.equals(requiredAddress);
        }

        byte[] remAddr = remoteAddress.getAddress();
        byte[] reqAddr = requiredAddress.getAddress();

        int nMaskFullBytes = nMaskBits / 8;
        byte finalByte = (byte) (0xFF00 >> (nMaskBits & 0x07));

        // System.out.println("Mask is " + new sun.misc.HexDumpEncoder().encode(mask));

        for (int i = 0; i < nMaskFullBytes; i++) {
            if (remAddr[i] != reqAddr[i]) {
                return false;
            }
        }

        if (finalByte != 0) {
            return (remAddr[nMaskFullBytes] & finalByte) == (reqAddr[nMaskFullBytes] & finalByte);
        }

        return true;
    }

    private InetAddress parseAddress(String address) {
        try {
            return InetAddress.getByName(address);
        }
        catch (UnknownHostException e) {
            throw new IllegalArgumentException("Failed to parse address" + address, e);
        }
    }
}
