/*
 * Copyright (C) 2015 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 android.security.net.config;

import android.annotation.Nullable;
import android.net.InetAddresses;

import java.net.InetAddress;
import java.util.Locale;
import java.util.Set;


/** @hide */
public final class Domain {
    private static final Set<String> LOCALHOSTS = Set.of("localhost", "ip6-localhost");

    /**
     * Lower case hostname for this domain rule.
     */
    public final String hostname;

    /**
     * Whether this domain includes subdomains.
     */
    public final boolean subdomainsIncluded;

    public Domain(String hostname, boolean subdomainsIncluded) {
        if (hostname == null) {
            throw new NullPointerException("Hostname must not be null");
        }
        this.hostname = hostname.toLowerCase(Locale.US);
        this.subdomainsIncluded = subdomainsIncluded;
    }

    @Override
    public int hashCode() {
        return hostname.hashCode() ^ (subdomainsIncluded ? 1231 : 1237);
    }

    @Override
    public boolean equals(@Nullable Object other) {
        if (other == this) {
            return true;
        }
        if (!(other instanceof Domain)) {
            return false;
        }
        Domain otherDomain = (Domain) other;
        return otherDomain.subdomainsIncluded == this.subdomainsIncluded &&
                otherDomain.hostname.equals(this.hostname);
    }

    public boolean isLocalhost() {
        return isLocalhost(this.hostname);
    }

    /**
     * Whether the hostname is considered to be localhost or not.
     */
    public static boolean isLocalhost(String hostname) {
        if (LOCALHOSTS.contains(hostname)) {
            return true;
        }
        // RFC 2732: To use a literal IPv6 address in a URL, the literal
        // address should be enclosed in "[" and "]" characters.
        if (hostname.charAt(0) == '[' && hostname.charAt(hostname.length() - 1) == ']') {
            hostname = hostname.substring(1, hostname.length() - 1);
        }
        // parseNumericAddress raises an exception if the address is not valid.
        // We could use isNumericAddress beforehand to avoid the exception, but
        // this would imply parsing the address twice. Simply ignore
        // IllegalArgumentException.
        try {
            InetAddress addr = InetAddresses.parseNumericAddress(hostname);
            return addr.isLoopbackAddress();
        } catch (IllegalArgumentException e) { }
        return false;
    }
}