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Code Issues Releases Wiki Activity

Fix Smack-225

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git-svn-id: http://svn.igniterealtime.org/svn/repos/smack/trunk@10961 b35dd754-fafc-0310-a699-88a17e54d16e
This commit is contained in:
Jeff Williams 2009-02-24 00:24:06 +00:00 committed by jeff.williams
parent ac2c9b09dc
commit fdca9b339d
1 changed files with 49 additions and 13 deletions
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62
source/org/jivesoftware/smack/util/DNSUtil.java
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@ -19,11 +19,14 @@
package org.jivesoftware.smack.util;
import java.util.Hashtable;
import java.util.Map;
import javax.naming.NamingEnumeration;
import javax.naming.directory.Attribute;
import javax.naming.directory.Attributes;
import javax.naming.directory.DirContext;
import javax.naming.directory.InitialDirContext;
import java.util.Hashtable;
import java.util.Map;
/**
* Utilty class to perform DNS lookups for XMPP services.
@ -63,6 +66,13 @@ public class DNSUtil {
* of 5222.<p>
*
* As an example, a lookup for "example.com" may return "im.example.com:5269".
*
* Note on SRV record selection.
* We now check priority and weight, but we still don't do this correctly.
* The missing behavior is this: if we fail to reach a host based on its SRV
* record then we need to select another host from the other SRV records.
* In Smack 3.1.1 we're not going to be able to do the major system redesign to
* correct this.
*
* @param domain the domain.
* @return a HostAddress, which encompasses the hostname and port that the XMPP
@ -80,24 +90,50 @@ public class DNSUtil {
return address;
}
}
String host = domain;
int port = 5222;
String bestHost = domain;
int bestPort = 5222;
int bestPriority = 0;
int bestWeight = 0;
try {
Attributes dnsLookup =
context.getAttributes("_xmpp-client._tcp." + domain, new String[]{"SRV"});
String srvRecord = (String)dnsLookup.get("SRV").get();
String [] srvRecordEntries = srvRecord.split(" ");
port = Integer.parseInt(srvRecordEntries[srvRecordEntries.length-2]);
host = srvRecordEntries[srvRecordEntries.length-1];
Attributes dnsLookup = context.getAttributes("_xmpp-client._tcp." + domain, new String[]{"SRV"});
Attribute srvAttribute = dnsLookup.get("SRV");
NamingEnumeration srvRecords = srvAttribute.getAll();
while(srvRecords.hasMore()) {
String srvRecord = (String) srvRecords.next();
String [] srvRecordEntries = srvRecord.split(" ");
int priority = Integer.parseInt(srvRecordEntries[srvRecordEntries.length - 4]);
int port = Integer.parseInt(srvRecordEntries[srvRecordEntries.length-2]);
int weight = Integer.parseInt(srvRecordEntries[srvRecordEntries.length - 3]);
String host = srvRecordEntries[srvRecordEntries.length-1];
// Randomize the weight.
weight *= Math.random() * weight;
if ((bestPriority == 0) || (priority < bestPriority)) {
// Choose a server with the lowest priority.
bestPriority = priority;
bestWeight = weight;
bestHost = host;
bestPort = port;
} else if (priority == bestPriority) {
// When we have like priorities then randomly choose a server based on its weight
// The weights were randomized above.
if (weight > bestWeight) {
bestWeight = weight;
bestHost = host;
bestPort = port;
}
}
}
}
catch (Exception e) {
// Ignore.
}
// Host entries in DNS should end with a ".".
if (host.endsWith(".")) {
host = host.substring(0, host.length()-1);
if (bestHost.endsWith(".")) {
bestHost = bestHost.substring(0, bestHost.length()-1);
}
HostAddress address = new HostAddress(host, port);
HostAddress address = new HostAddress(bestHost, bestPort);
// Add item to cache.
cache.put(key, address);
return address;