RemoteXmppTcpConnectionEndpoints.java
/**
*
* Copyright 2015-2020 Florian Schmaus.
*
* 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 org.jivesoftware.smack.tcp.rce;
import java.net.InetAddress;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.jivesoftware.smack.ConnectionConfiguration;
import org.jivesoftware.smack.ConnectionConfiguration.DnssecMode;
import org.jivesoftware.smack.datatypes.UInt16;
import org.jivesoftware.smack.util.DNSUtil;
import org.jivesoftware.smack.util.dns.DNSResolver;
import org.jivesoftware.smack.util.rce.RemoteConnectionEndpoint;
import org.jivesoftware.smack.util.rce.RemoteConnectionEndpointLookupFailure;
import org.minidns.dnsname.DnsName;
import org.minidns.record.InternetAddressRR;
import org.minidns.record.SRV;
import org.minidns.util.SrvUtil;
public class RemoteXmppTcpConnectionEndpoints {
private static final Logger LOGGER = Logger.getLogger(RemoteXmppTcpConnectionEndpoints.class.getName());
public static final String XMPP_CLIENT_DNS_SRV_PREFIX = "_xmpp-client._tcp";
public static final String XMPP_SERVER_DNS_SRV_PREFIX = "_xmpp-server._tcp";
/**
* Lookups remote connection endpoints on the server for XMPP connections over TCP taking A, AAAA and SRV resource
* records into account. If no host address was configured and all lookups failed, for example with NX_DOMAIN, then
* result will be populated with the empty list.
*
* @param config the connection configuration to lookup the endpoints for.
* @return a lookup result.
*/
public static Result<Rfc6120TcpRemoteConnectionEndpoint> lookup(ConnectionConfiguration config) {
List<Rfc6120TcpRemoteConnectionEndpoint> discoveredRemoteConnectionEndpoints;
List<RemoteConnectionEndpointLookupFailure> lookupFailures;
final InetAddress hostAddress = config.getHostAddress();
final DnsName host = config.getHost();
if (hostAddress != null) {
lookupFailures = Collections.emptyList();
IpTcpRemoteConnectionEndpoint<InternetAddressRR<?>> connectionEndpoint = IpTcpRemoteConnectionEndpoint.from(
hostAddress.toString(), config.getPort(), hostAddress);
discoveredRemoteConnectionEndpoints = Collections.singletonList(connectionEndpoint);
} else if (host != null) {
lookupFailures = new ArrayList<>(1);
List<InetAddress> hostAddresses = DNSUtil.getDNSResolver().lookupHostAddress(host,
lookupFailures, config.getDnssecMode());
if (hostAddresses != null) {
discoveredRemoteConnectionEndpoints = new ArrayList<>(hostAddresses.size());
UInt16 port = config.getPort();
for (InetAddress inetAddress : hostAddresses) {
IpTcpRemoteConnectionEndpoint<InternetAddressRR<?>> connectionEndpoint = IpTcpRemoteConnectionEndpoint.from(
host, port, inetAddress);
discoveredRemoteConnectionEndpoints.add(connectionEndpoint);
}
} else {
discoveredRemoteConnectionEndpoints = Collections.emptyList();
}
} else {
lookupFailures = new ArrayList<>();
// N.B.: Important to use config.serviceName and not AbstractXMPPConnection.serviceName
DnsName dnsName = config.getXmppServiceDomainAsDnsNameIfPossible();
if (dnsName == null) {
// TODO: ConnectionConfiguration should check on construction time that either the given XMPP service
// name is also a valid DNS name, or that a host is explicitly configured.
throw new IllegalStateException();
}
discoveredRemoteConnectionEndpoints = resolveXmppServiceDomain(dnsName, lookupFailures, config.getDnssecMode());
}
// Either the populated host addresses are not empty *or* there must be at least one failed address.
assert !discoveredRemoteConnectionEndpoints.isEmpty() || !lookupFailures.isEmpty();
return new Result<>(discoveredRemoteConnectionEndpoints, lookupFailures);
}
public static final class Result<RCE extends RemoteConnectionEndpoint> {
public final List<RCE> discoveredRemoteConnectionEndpoints;
public final List<RemoteConnectionEndpointLookupFailure> lookupFailures;
private Result(List<RCE> discoveredRemoteConnectionEndpoints, List<RemoteConnectionEndpointLookupFailure> lookupFailures) {
this.discoveredRemoteConnectionEndpoints = discoveredRemoteConnectionEndpoints;
this.lookupFailures = lookupFailures;
}
}
@SuppressWarnings("ImmutableEnumChecker")
enum DomainType {
server(XMPP_SERVER_DNS_SRV_PREFIX),
client(XMPP_CLIENT_DNS_SRV_PREFIX),
;
public final DnsName srvPrefix;
DomainType(String srvPrefixString) {
srvPrefix = DnsName.from(srvPrefixString);
}
}
/**
* Returns a list of HostAddresses under which the specified XMPP server can be reached at for client-to-server
* communication. A DNS lookup for a SRV record in the form "_xmpp-client._tcp.example.com" is attempted, according
* to section 3.2.1 of RFC 6120. If that lookup fails, it's assumed that the XMPP server lives at the host resolved
* by a DNS lookup at the specified domain on the default port of 5222.
* <p>
* As an example, a lookup for "example.com" may return "im.example.com:5269".
* </p>
*
* @param domain the domain.
* @param lookupFailures on optional list that will be populated with host addresses that failed to resolve.
* @param dnssecMode DNSSec mode.
* @return List of HostAddress, which encompasses the hostname and port that the
* XMPP server can be reached at for the specified domain.
*/
public static List<Rfc6120TcpRemoteConnectionEndpoint> resolveXmppServiceDomain(DnsName domain,
List<RemoteConnectionEndpointLookupFailure> lookupFailures, DnssecMode dnssecMode) {
DNSResolver dnsResolver = getDnsResolverOrThrow();
return resolveDomain(domain, DomainType.client, lookupFailures, dnssecMode, dnsResolver);
}
/**
* Returns a list of HostAddresses under which the specified XMPP server can be reached at for server-to-server
* communication. A DNS lookup for a SRV record in the form "_xmpp-server._tcp.example.com" is attempted, according
* to section 3.2.1 of RFC 6120. If that lookup fails , it's assumed that the XMPP server lives at the host resolved
* by a DNS lookup at the specified domain on the default port of 5269.
* <p>
* As an example, a lookup for "example.com" may return "im.example.com:5269".
* </p>
*
* @param domain the domain.
* @param lookupFailures a list that will be populated with host addresses that failed to resolve.
* @param dnssecMode DNSSec mode.
* @return List of HostAddress, which encompasses the hostname and port that the
* XMPP server can be reached at for the specified domain.
*/
public static List<Rfc6120TcpRemoteConnectionEndpoint> resolveXmppServerDomain(DnsName domain,
List<RemoteConnectionEndpointLookupFailure> lookupFailures, DnssecMode dnssecMode) {
DNSResolver dnsResolver = getDnsResolverOrThrow();
return resolveDomain(domain, DomainType.server, lookupFailures, dnssecMode, dnsResolver);
}
/**
*
* @param domain the domain.
* @param domainType the XMPP domain type, server or client.
* @param failedAddresses a list that will be populated with host addresses that failed to resolve.
* @return a list of resolver host addresses for this domain.
*/
private static List<Rfc6120TcpRemoteConnectionEndpoint> resolveDomain(DnsName domain, DomainType domainType,
List<RemoteConnectionEndpointLookupFailure> lookupFailures, DnssecMode dnssecMode, DNSResolver dnsResolver) {
List<Rfc6120TcpRemoteConnectionEndpoint> endpoints = new ArrayList<>();
// Step one: Do SRV lookups
DnsName srvDomain = DnsName.from(domainType.srvPrefix, domain);
Collection<SRV> srvRecords = dnsResolver.lookupSrvRecords(srvDomain, lookupFailures, dnssecMode);
if (srvRecords != null && !srvRecords.isEmpty()) {
if (LOGGER.isLoggable(Level.FINE)) {
String logMessage = "Resolved SRV RR for " + srvDomain + ":";
for (SRV r : srvRecords)
logMessage += " " + r;
LOGGER.fine(logMessage);
}
List<SRV> sortedSrvRecords = SrvUtil.sortSrvRecords(srvRecords);
for (SRV srv : sortedSrvRecords) {
List<InetAddress> targetInetAddresses = dnsResolver.lookupHostAddress(srv.target, lookupFailures, dnssecMode);
SrvXmppRemoteConnectionEndpoint endpoint = new SrvXmppRemoteConnectionEndpoint(srv, targetInetAddresses);
endpoints.add(endpoint);
}
} else {
LOGGER.info("Could not resolve DNS SRV resource records for " + srvDomain + ". Consider adding those.");
}
UInt16 defaultPort;
switch (domainType) {
case client:
defaultPort = UInt16.from(5222);
break;
case server:
defaultPort = UInt16.from(5269);
break;
default:
throw new AssertionError();
}
// Step two: Add the hostname to the end of the list
List<InetAddress> hostAddresses = dnsResolver.lookupHostAddress(domain, lookupFailures, dnssecMode);
if (hostAddresses != null) {
for (InetAddress inetAddress : hostAddresses) {
IpTcpRemoteConnectionEndpoint<InternetAddressRR<?>> endpoint = IpTcpRemoteConnectionEndpoint.from(domain, defaultPort, inetAddress);
endpoints.add(endpoint);
}
}
return endpoints;
}
private static DNSResolver getDnsResolverOrThrow() {
final DNSResolver dnsResolver = DNSUtil.getDNSResolver();
if (dnsResolver == null) {
throw new IllegalStateException("No DNS resolver configured in Smack");
}
return dnsResolver;
}
}