com.spotify.dns.XBillDnsSrvResolver.java Source code

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Here is the source code for com.spotify.dns.XBillDnsSrvResolver.java

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/*
 * Copyright (c) 2015 Spotify AB
 *
 * 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 com.spotify.dns;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.xbill.DNS.Lookup;
import org.xbill.DNS.Record;
import org.xbill.DNS.SRVRecord;

import java.util.List;

/**
 * A DnsSrvResolver implementation that uses the dnsjava implementation from xbill.org:
 * http://www.xbill.org/dnsjava/
 */
class XBillDnsSrvResolver implements DnsSrvResolver {
    private static final Logger LOG = LoggerFactory.getLogger(XBillDnsSrvResolver.class);

    private final LookupFactory lookupFactory;

    XBillDnsSrvResolver(LookupFactory lookupFactory) {
        this.lookupFactory = Preconditions.checkNotNull(lookupFactory, "lookupFactory");
    }

    @Override
    public List<LookupResult> resolve(final String fqdn) {
        Lookup lookup = lookupFactory.forName(fqdn);
        Record[] queryResult = lookup.run();

        switch (lookup.getResult()) {
        case Lookup.SUCCESSFUL:
            return toLookupResults(queryResult);
        case Lookup.HOST_NOT_FOUND:
            // fallthrough
        case Lookup.TYPE_NOT_FOUND:
            LOG.warn("No results returned for query '{}'; result from XBill: {} - {}", fqdn, lookup.getResult(),
                    lookup.getErrorString());
            return ImmutableList.of();
        default:
            throw new DnsException(String.format("Lookup of '%s' failed with code: %d - %s ", fqdn,
                    lookup.getResult(), lookup.getErrorString()));
        }
    }

    private static List<LookupResult> toLookupResults(Record[] queryResult) {
        ImmutableList.Builder<LookupResult> builder = ImmutableList.builder();

        if (queryResult != null) {
            for (Record record : queryResult) {
                if (record instanceof SRVRecord) {
                    SRVRecord srvRecord = (SRVRecord) record;
                    builder.add(LookupResult.create(srvRecord.getTarget().toString(), srvRecord.getPort(),
                            srvRecord.getPriority(), srvRecord.getWeight(), srvRecord.getTTL()));
                }
            }
        }

        return builder.build();
    }
}