291 lines
11 KiB
Java
291 lines
11 KiB
Java
/**
|
|
*
|
|
* Copyright 2003-2005 Jive Software, 2016 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.util;
|
|
|
|
import java.util.ArrayList;
|
|
import java.util.Collections;
|
|
import java.util.LinkedList;
|
|
import java.util.List;
|
|
import java.util.SortedMap;
|
|
import java.util.TreeMap;
|
|
import java.util.logging.Level;
|
|
import java.util.logging.Logger;
|
|
|
|
import org.jivesoftware.smack.ConnectionConfiguration.DnssecMode;
|
|
import org.jivesoftware.smack.util.dns.DNSResolver;
|
|
import org.jivesoftware.smack.util.dns.SmackDaneProvider;
|
|
import org.jivesoftware.smack.util.dns.HostAddress;
|
|
import org.jivesoftware.smack.util.dns.SRVRecord;
|
|
|
|
/**
|
|
* Utility class to perform DNS lookups for XMPP services.
|
|
*
|
|
* @author Matt Tucker
|
|
* @author Florian Schmaus
|
|
*/
|
|
public class DNSUtil {
|
|
|
|
private static final Logger LOGGER = Logger.getLogger(DNSUtil.class.getName());
|
|
private static DNSResolver dnsResolver = null;
|
|
private static SmackDaneProvider daneProvider;
|
|
|
|
/**
|
|
* International Domain Name transformer.
|
|
* <p>
|
|
* Used to transform Unicode representations of the Domain Name to ASCII in
|
|
* order to perform a DNS request with the ASCII representation.
|
|
* 'java.net.IDN' is available since Android API 9, but as long as Smack
|
|
* requires API 8, we are going to need this. This part is going to get
|
|
* removed once Smack depends on Android API 9 or higher.
|
|
* </p>
|
|
*/
|
|
private static StringTransformer idnaTransformer = new StringTransformer() {
|
|
@Override
|
|
public String transform(String string) {
|
|
return string;
|
|
}
|
|
};
|
|
|
|
/**
|
|
* Set the DNS resolver that should be used to perform DNS lookups.
|
|
*
|
|
* @param resolver
|
|
*/
|
|
public static void setDNSResolver(DNSResolver resolver) {
|
|
dnsResolver = Objects.requireNonNull(resolver);
|
|
}
|
|
|
|
/**
|
|
* Returns the current DNS resolved used to perform DNS lookups.
|
|
*
|
|
* @return the active DNSResolver
|
|
*/
|
|
public static DNSResolver getDNSResolver() {
|
|
return dnsResolver;
|
|
}
|
|
|
|
/**
|
|
* Set the DANE provider that should be used when DANE is enabled.
|
|
*
|
|
* @param daneProvider
|
|
*/
|
|
public static void setDaneProvider(SmackDaneProvider daneProvider) {
|
|
daneProvider = Objects.requireNonNull(daneProvider);
|
|
}
|
|
|
|
/**
|
|
* Returns the currently active DANE provider used when DANE is enabled.
|
|
*
|
|
* @return the active DANE provider
|
|
*/
|
|
public static SmackDaneProvider getDaneProvider() {
|
|
return daneProvider;
|
|
}
|
|
|
|
/**
|
|
* Set the IDNA (Internationalizing Domain Names in Applications, RFC 3490) transformer.
|
|
* <p>
|
|
* You usually want to wrap 'java.net.IDN.toASCII()' into a StringTransformer here.
|
|
* </p>
|
|
* @param idnaTransformer
|
|
*/
|
|
public static void setIdnaTransformer(StringTransformer idnaTransformer) {
|
|
if (idnaTransformer == null) {
|
|
throw new NullPointerException();
|
|
}
|
|
DNSUtil.idnaTransformer = idnaTransformer;
|
|
}
|
|
|
|
private static enum DomainType {
|
|
Server,
|
|
Client,
|
|
;
|
|
}
|
|
|
|
/**
|
|
* 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 failedAddresses on optional list that will be populated with host addresses that failed to resolve.
|
|
* @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<HostAddress> resolveXMPPServiceDomain(String domain, List<HostAddress> failedAddresses, DnssecMode dnssecMode) {
|
|
domain = idnaTransformer.transform(domain);
|
|
|
|
return resolveDomain(domain, DomainType.Client, failedAddresses, dnssecMode);
|
|
}
|
|
|
|
/**
|
|
* 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 failedAddresses on optional list that will be populated with host addresses that failed to resolve.
|
|
* @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<HostAddress> resolveXMPPServerDomain(String domain, List<HostAddress> failedAddresses, DnssecMode dnssecMode) {
|
|
domain = idnaTransformer.transform(domain);
|
|
|
|
return resolveDomain(domain, DomainType.Server, failedAddresses, dnssecMode);
|
|
}
|
|
|
|
/**
|
|
*
|
|
* @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<HostAddress> resolveDomain(String domain, DomainType domainType,
|
|
List<HostAddress> failedAddresses, DnssecMode dnssecMode) {
|
|
if (dnsResolver == null) {
|
|
throw new IllegalStateException("No DNS Resolver active in Smack");
|
|
}
|
|
|
|
List<HostAddress> addresses = new ArrayList<HostAddress>();
|
|
|
|
// Step one: Do SRV lookups
|
|
String srvDomain;
|
|
switch (domainType) {
|
|
case Server:
|
|
srvDomain = "_xmpp-server._tcp." + domain;
|
|
break;
|
|
case Client:
|
|
srvDomain = "_xmpp-client._tcp." + domain;
|
|
break;
|
|
default:
|
|
throw new AssertionError();
|
|
}
|
|
|
|
List<SRVRecord> srvRecords = dnsResolver.lookupSRVRecords(srvDomain, failedAddresses, dnssecMode);
|
|
if (srvRecords != null) {
|
|
if (LOGGER.isLoggable(Level.FINE)) {
|
|
String logMessage = "Resolved SRV RR for " + srvDomain + ":";
|
|
for (SRVRecord r : srvRecords)
|
|
logMessage += " " + r;
|
|
LOGGER.fine(logMessage);
|
|
}
|
|
List<HostAddress> sortedRecords = sortSRVRecords(srvRecords);
|
|
addresses.addAll(sortedRecords);
|
|
}
|
|
|
|
// Step two: Add the hostname to the end of the list
|
|
HostAddress hostAddress = dnsResolver.lookupHostAddress(domain, failedAddresses, dnssecMode);
|
|
if (hostAddress != null) {
|
|
addresses.add(hostAddress);
|
|
}
|
|
|
|
return addresses;
|
|
}
|
|
|
|
/**
|
|
* Sort a given list of SRVRecords as described in RFC 2782
|
|
* Note that we follow the RFC with one exception. In a group of the same priority, only the first entry
|
|
* is calculated by random. The others are ore simply ordered by their priority.
|
|
*
|
|
* @param records
|
|
* @return the list of resolved HostAddresses
|
|
*/
|
|
private static List<HostAddress> sortSRVRecords(List<SRVRecord> records) {
|
|
// RFC 2782, Usage rules: "If there is precisely one SRV RR, and its Target is "."
|
|
// (the root domain), abort."
|
|
if (records.size() == 1 && records.get(0).getFQDN().equals("."))
|
|
return Collections.emptyList();
|
|
|
|
// sorting the records improves the performance of the bisection later
|
|
Collections.sort(records);
|
|
|
|
// create the priority buckets
|
|
SortedMap<Integer, List<SRVRecord>> buckets = new TreeMap<Integer, List<SRVRecord>>();
|
|
for (SRVRecord r : records) {
|
|
Integer priority = r.getPriority();
|
|
List<SRVRecord> bucket = buckets.get(priority);
|
|
// create the list of SRVRecords if it doesn't exist
|
|
if (bucket == null) {
|
|
bucket = new LinkedList<SRVRecord>();
|
|
buckets.put(priority, bucket);
|
|
}
|
|
bucket.add(r);
|
|
}
|
|
|
|
List<HostAddress> res = new ArrayList<HostAddress>(records.size());
|
|
|
|
for (Integer priority : buckets.keySet()) {
|
|
List<SRVRecord> bucket = buckets.get(priority);
|
|
int bucketSize;
|
|
while ((bucketSize = bucket.size()) > 0) {
|
|
int[] totals = new int[bucket.size()];
|
|
int running_total = 0;
|
|
int count = 0;
|
|
int zeroWeight = 1;
|
|
|
|
for (SRVRecord r : bucket) {
|
|
if (r.getWeight() > 0)
|
|
zeroWeight = 0;
|
|
}
|
|
|
|
for (SRVRecord r : bucket) {
|
|
running_total += (r.getWeight() + zeroWeight);
|
|
totals[count] = running_total;
|
|
count++;
|
|
}
|
|
int selectedPos;
|
|
if (running_total == 0) {
|
|
// If running total is 0, then all weights in this priority
|
|
// group are 0. So we simply select one of the weights randomly
|
|
// as the other 'normal' algorithm is unable to handle this case
|
|
selectedPos = (int) (Math.random() * bucketSize);
|
|
} else {
|
|
double rnd = Math.random() * running_total;
|
|
selectedPos = bisect(totals, rnd);
|
|
}
|
|
// add the SRVRecord that was randomly chosen on it's weight
|
|
// to the start of the result list
|
|
SRVRecord chosenSRVRecord = bucket.remove(selectedPos);
|
|
res.add(chosenSRVRecord);
|
|
}
|
|
}
|
|
|
|
return res;
|
|
}
|
|
|
|
// TODO this is not yet really bisection just a stupid linear search
|
|
private static int bisect(int[] array, double value) {
|
|
int pos = 0;
|
|
for (int element : array) {
|
|
if (value < element)
|
|
break;
|
|
pos++;
|
|
}
|
|
return pos;
|
|
}
|
|
|
|
}
|