resolver/src/main/java/org/apache/james/jspf/executor/SynchronousSPFExecutor.java

/****************************************************************
 * Licensed to the Apache Software Foundation (ASF) under one   *
 * or more contributor license agreements.  See the NOTICE file *
 * distributed with this work for additional information        *
 * regarding copyright ownership.  The ASF licenses this file   *
 * to you 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.apache.james.jspf.executor;

import org.apache.james.jspf.core.DNSLookupContinuation;
import org.apache.james.jspf.core.DNSResponse;
import org.apache.james.jspf.core.DNSService;
import org.apache.james.jspf.core.SPFChecker;
import org.apache.james.jspf.core.SPFCheckerExceptionCatcher;
import org.apache.james.jspf.core.SPFSession;
import org.apache.james.jspf.core.exceptions.SPFResultException;
import org.apache.james.jspf.core.exceptions.TimeoutException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Synchronous implementation of SPFExecuter. All queries will get executed synchronously
 */
public class SynchronousSPFExecutor implements SPFExecutor {
    private static final Logger LOGGER = LoggerFactory.getLogger(SynchronousSPFExecutor.class);

    private DNSService dnsProbe;

    public SynchronousSPFExecutor(DNSService service) {
        this.dnsProbe = service;
    }

    /**
     * @see org.apache.james.jspf.executor.SPFExecutor#execute(org.apache.james.jspf.core.SPFSession, org.apache.james.jspf.executor.FutureSPFResult)
     */
    public void execute(SPFSession session, FutureSPFResult result) {
        SPFChecker checker;
        while ((checker = session.popChecker()) != null) {
            // only execute checkers we added (better recursivity)
            LOGGER.debug("Executing checker: {}", checker);
            try {
                DNSLookupContinuation cont = checker.checkSPF(session);
                // if the checker returns a continuation we return it
                while (cont != null) {
                    DNSResponse response;
                    try {
                        response = new DNSResponse(dnsProbe.getRecords(cont
                                .getRequest()));
                    } catch (TimeoutException e) {
                        response = new DNSResponse(e);
                    }
                    cont = cont.getListener().onDNSResponse(response, session);
                }
            } catch (Exception e) {
                while (e != null) {
                    while (checker == null || !(checker instanceof SPFCheckerExceptionCatcher)) {
                        checker = session.popChecker();
                    }
                    try {
                        ((SPFCheckerExceptionCatcher) checker).onException(e, session);
                        e = null;
                    } catch (SPFResultException ex) {
                        e = ex;
                    } finally {
                        checker = null;
                    }
                }
            }
        }
        result.setSPFResult(session);
    }

}