org.springframework.vault.authentication.MacAddressUserId.java Source code

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Here is the source code for org.springframework.vault.authentication.MacAddressUserId.java

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/*
 * Copyright 2016 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
 *
 *      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 org.springframework.vault.authentication;

import java.io.IOException;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.util.Collections;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

/**
 * Mechanism to generate a UserId based on the Mac address. {@link MacAddressUserId}
 * creates a hex-encoded representation of the Mac address without any separators
 * (0123456789AB). A network interface hint can be specified optionally to select a
 * network interface (index/name).
 *
 * @author Mark Paluch
 * @see AppIdUserIdMechanism
 */
public class MacAddressUserId implements AppIdUserIdMechanism {

    private final Log log = LogFactory.getLog(MacAddressUserId.class);

    private final String networkInterfaceHint;

    /**
     * Creates a new {@link MacAddressUserId} using the {@link NetworkInterface} from the
     * {@link InetAddress#getLocalHost()}.
     */
    public MacAddressUserId() {
        this("");
    }

    /**
     * Creates a new {@link MacAddressUserId} using a {@code networkInterfaceIndex}. The
     * index is applied to {@link NetworkInterface#getNetworkInterfaces()} to obtain the
     * desired network interface.
     * 
     * @param networkInterfaceIndex must be greater or equal to zero.
     */
    public MacAddressUserId(int networkInterfaceIndex) {

        Assert.isTrue(networkInterfaceIndex >= 0, "NetworkInterfaceIndex must be greater or equal to 0");

        this.networkInterfaceHint = "" + networkInterfaceIndex;
    }

    /**
     * Creates a new {@link MacAddressUserId} using a {@code networkInterfaceName}. This
     * name is compared with {@link NetworkInterface#getName()} and
     * {@link NetworkInterface#getDisplayName()} to obtain the desired network interface.
     *
     * @param networkInterfaceName must not be {@literal null}.
     */
    public MacAddressUserId(String networkInterfaceName) {

        Assert.notNull(networkInterfaceName, "NetworkInterfaceName must not be null");

        this.networkInterfaceHint = networkInterfaceName;
    }

    @Override
    public String createUserId() {

        try {

            NetworkInterface networkInterface = null;
            List<NetworkInterface> interfaces = Collections.list(NetworkInterface.getNetworkInterfaces());

            if (StringUtils.hasText(networkInterfaceHint)) {

                try {
                    networkInterface = getNetworkInterface(Integer.parseInt(networkInterfaceHint), interfaces);
                } catch (NumberFormatException e) {
                    networkInterface = getNetworkInterface((networkInterfaceHint), interfaces);
                }
            }

            if (networkInterface == null) {

                if (StringUtils.hasText(networkInterfaceHint)) {
                    log.warn(String.format("Did not find a NetworkInterface applying hint %s",
                            networkInterfaceHint));
                }

                InetAddress localHost = InetAddress.getLocalHost();
                networkInterface = NetworkInterface.getByInetAddress(localHost);

                if (networkInterface == null) {
                    throw new IllegalStateException(
                            String.format("Cannot determine NetworkInterface for %s", localHost));
                }
            }

            byte[] mac = networkInterface.getHardwareAddress();
            if (mac == null) {
                throw new IllegalStateException(
                        String.format("Network interface %s has no hardware address", networkInterface.getName()));
            }

            return Sha256.toSha256(Sha256.toHexString(mac));
        } catch (IOException e) {
            throw new IllegalStateException(e);
        }
    }

    private NetworkInterface getNetworkInterface(Number hint, List<NetworkInterface> interfaces) {

        if (interfaces.size() > hint.intValue() && hint.intValue() >= 0) {
            return interfaces.get(hint.intValue());
        }

        return null;
    }

    private NetworkInterface getNetworkInterface(String hint, List<NetworkInterface> interfaces) {

        for (NetworkInterface anInterface : interfaces) {
            if (hint.equals(anInterface.getDisplayName()) || hint.equals(anInterface.getName())) {
                return anInterface;
            }
        }

        return null;
    }
}