de.is24.aws.instancemetadataserver.RemoteHostRoleNameProducer.java Source code

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Here is the source code for de.is24.aws.instancemetadataserver.RemoteHostRoleNameProducer.java

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/**
 * AWS Instance Metadata Server
 * Copyright 2015 Immobilien Scout GmbH
 *
 * 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 de.is24.aws.instancemetadataserver;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Service;

import javax.servlet.http.HttpServletRequest;
import java.util.Optional;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

@Service
public class RemoteHostRoleNameProducer implements RoleNameProducer {
    private static final Logger LOG = LoggerFactory.getLogger(RemoteHostRoleNameProducer.class);

    @Override
    public Optional<String> getRoleName(HttpServletRequest request) {
        String hostName = request.getRemoteHost();
        Optional<String> roleName = toRoleName(hostName);
        if (!roleName.isPresent()) {
            LOG.info("Unable to generate a role name for host {}.", hostName);
        }
        return roleName;
    }

    private Optional<String> toRoleName(String hostName) {
        return Optional.of(hostName).flatMap(this::getHostPart).flatMap(this::stripHostNr)
                .flatMap(this::unifyHamAndBerToPro).map(this::addRzPrefix);
    }

    private String addRzPrefix(String rawLocTyp) {
        return "rz_" + rawLocTyp;
    }

    private Optional<String> unifyHamAndBerToPro(String rawLocTyp) {
        Matcher matcher = Pattern.compile("^((ber)|(ham))(.+)$").matcher(rawLocTyp);

        if (!matcher.find()) {
            return Optional.of(rawLocTyp);
        }

        return Optional.ofNullable(matcher.group(4)).map((typ) -> "pro" + typ);
    }

    private Optional<String> stripHostNr(String rawHostName) {
        Matcher matcher = Pattern.compile("^([a-zA-Z]+)[0-9]+$").matcher(rawHostName);

        if (!matcher.find()) {
            return Optional.empty();
        }

        return Optional.ofNullable(matcher.group(1));

    }

    private Optional<String> getHostPart(String rawFqdn) {
        Matcher matcher = Pattern.compile("^([a-zA-Z0-9]+)(\\.d)?\\.rz\\.is$").matcher(rawFqdn);

        if (!matcher.find()) {
            return Optional.empty();
        }

        return Optional.ofNullable(matcher.group(1));
    }
}