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

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 * 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   *
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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.NeutralException;
import org.apache.james.jspf.core.exceptions.NoneException;
import org.apache.james.jspf.core.exceptions.PermErrorException;
import org.apache.james.jspf.core.exceptions.SPFResultException;
import org.apache.james.jspf.core.exceptions.TempErrorException;
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 AsynchronousSPFExecutor implements SPFExecutor {
    private static final Logger LOGGER = LoggerFactory.getLogger(AsynchronousSPFExecutor.class);

    private DNSService dnsProbe;

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

    /**
     * @see SPFExecutor#execute(SPFSession, 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);
            final SPFChecker finalChecker = checker;
            try {
                final DNSLookupContinuation cont = checker.checkSPF(session);
                // if the checker returns a continuation we return it
                dnsProbe.getRecordsAsync(cont.getRequest())
                    .thenAccept(results -> {
                        try {
                            cont.getListener().onDNSResponse(new DNSResponse(results), session);
                        } catch (PermErrorException | NoneException | TempErrorException | NeutralException e) {
                            handleError(session, finalChecker, e);
                        }
                    })
                    .exceptionally(e -> {
                        if (e instanceof TimeoutException) {
                            try {
                                cont.getListener().onDNSResponse(new DNSResponse((TimeoutException) e), session);
                            } catch (PermErrorException | NoneException | TempErrorException | NeutralException ex2) {
                                handleError(session, finalChecker, ex2);
                            }
                        }
                        return null;
                    });
            } catch (Exception e) {
                handleError(session, checker, e);
            }
        }
        result.setSPFResult(session);
    }

    private void handleError(SPFSession session, SPFChecker checker, 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;
            }
        }
    }
}