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cc636fff21
This is a complete redesign of what was previously XmppNioTcpConnection. The new architecture allows to extend an XMPP client to server (c2s) connection with new transport bindings and other extensions.
124 lines
5.1 KiB
Java
124 lines
5.1 KiB
Java
/**
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*
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* Copyright 2013-2020 Florian Schmaus
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.jivesoftware.smack.util.dns;
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import java.net.InetAddress;
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import java.net.UnknownHostException;
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import java.util.Arrays;
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import java.util.Collection;
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import java.util.List;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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import org.jivesoftware.smack.ConnectionConfiguration.DnssecMode;
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import org.jivesoftware.smack.util.rce.RemoteConnectionEndpointLookupFailure;
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import org.minidns.dnsname.DnsName;
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import org.minidns.record.SRV;
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/**
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* Implementations of this interface define a class that is capable of resolving DNS addresses.
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*
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*/
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public abstract class DNSResolver {
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protected static final Logger LOGGER = Logger.getLogger(DNSResolver.class.getName());
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private final boolean supportsDnssec;
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protected DNSResolver(boolean supportsDnssec) {
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this.supportsDnssec = supportsDnssec;
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}
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/**
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* Gets a list of service records for the specified service.
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*
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* @param name The symbolic name of the service.
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* @param lookupFailures list of exceptions that occurred during lookup.
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* @param dnssecMode security mode.
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* @return The list of SRV records mapped to the service name.
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*/
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public final Collection<SRV> lookupSrvRecords(DnsName name,
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List<RemoteConnectionEndpointLookupFailure> lookupFailures, DnssecMode dnssecMode) {
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checkIfDnssecRequestedAndSupported(dnssecMode);
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return lookupSrvRecords0(name, lookupFailures, dnssecMode);
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}
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protected abstract Collection<SRV> lookupSrvRecords0(DnsName name,
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List<RemoteConnectionEndpointLookupFailure> lookupFailures, DnssecMode dnssecMode);
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public final List<InetAddress> lookupHostAddress(DnsName name,
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List<RemoteConnectionEndpointLookupFailure> lookupFailures, DnssecMode dnssecMode) {
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checkIfDnssecRequestedAndSupported(dnssecMode);
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return lookupHostAddress0(name, lookupFailures, dnssecMode);
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}
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/**
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* Lookup the IP addresses of a given host name. Returns <code>null</code> if there was an error, in which the error
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* reason will be added in form of a <code>HostAddress</code> to <code>failedAddresses</code>. Returns a empty list
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* in case the DNS name exists but has no associated A or AAAA resource records. Otherwise, if the resolution was
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* successful <em>and</em> there is at least one A or AAAA resource record, then a non-empty list will be returned.
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* <p>
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* Concrete DNS resolver implementations are free to overwrite this, but have to stick to the interface contract.
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* </p>
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*
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* @param name the DNS name to lookup
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* @param lookupFailures list of exceptions that occurred during lookup.
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* @param dnssecMode the selected DNSSEC mode
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* @return A list, either empty or non-empty, or <code>null</code>
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*/
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protected List<InetAddress> lookupHostAddress0(DnsName name, List<RemoteConnectionEndpointLookupFailure> lookupFailures, DnssecMode dnssecMode) {
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// Default implementation of a DNS name lookup for A/AAAA records. It is assumed that this method does never
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// support DNSSEC. Subclasses are free to override this method.
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if (dnssecMode != DnssecMode.disabled) {
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throw new UnsupportedOperationException("This resolver does not support DNSSEC");
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}
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InetAddress[] inetAddressArray;
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try {
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inetAddressArray = InetAddress.getAllByName(name.toString());
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} catch (UnknownHostException e) {
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lookupFailures.add(new RemoteConnectionEndpointLookupFailure.DnsLookupFailure(name, e));
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return null;
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}
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return Arrays.asList(inetAddressArray);
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}
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protected static boolean shouldContinue(CharSequence name, CharSequence hostname, List<InetAddress> hostAddresses) {
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if (hostAddresses == null) {
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return true;
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}
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// If hostAddresses is not null but empty, then the DNS resolution was successful but the domain did not
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// have any A or AAAA resource records.
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if (hostAddresses.isEmpty()) {
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LOGGER.log(Level.INFO, "The DNS name " + name + ", points to a hostname (" + hostname
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+ ") which has neither A or AAAA resource records. This is an indication of a broken DNS setup.");
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return true;
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}
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return false;
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}
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private void checkIfDnssecRequestedAndSupported(DnssecMode dnssecMode) {
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if (dnssecMode != DnssecMode.disabled && !supportsDnssec) {
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throw new UnsupportedOperationException("This resolver does not support DNSSEC");
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}
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}
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}
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