SMACK-225 Fixed DNS SRV handling, as per RFC 2782. Added support for multiple DNS SRV resolvers namely javax and org.xbill.dns (aka dnsjava).

git-svn-id: http://svn.igniterealtime.org/svn/repos/smack/branches/smack_3_3_0@13561 b35dd754-fafc-0310-a699-88a17e54d16e

source/org/jivesoftware/smack/util/dns/DNSJavaResolver.java

@@ -0,0 +1,72 @@
+/**
+ * Copyright 2013 Florian Schmaus
+ *
+ * All rights reserved. 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.dns;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.xbill.DNS.Lookup;
+import org.xbill.DNS.Record;
+import org.xbill.DNS.Type;
+
+public class DNSJavaResolver extends DNSResolver {
+    
+    private static DNSJavaResolver instance;
+    
+    private DNSJavaResolver() {
+        
+    }
+    
+    public static DNSResolver getInstance() {
+        if (instance == null) {
+            instance = new DNSJavaResolver();
+        }
+        return instance;
+    }
+
+    @Override
+    public List<SRVRecord> lookupSRVRecords(String name) {
+        List<SRVRecord> res = new ArrayList<SRVRecord>();
+
+        try {
+            Lookup lookup = new Lookup(name, Type.SRV);
+            Record recs[] = lookup.run();
+            if (recs == null)
+                return res;
+
+            for (Record record : recs) {
+                org.xbill.DNS.SRVRecord srvRecord = (org.xbill.DNS.SRVRecord) record;
+                if (srvRecord != null && srvRecord.getTarget() != null) {
+                    String host = srvRecord.getTarget().toString();
+                    int port = srvRecord.getPort();
+                    int priority = srvRecord.getPriority();
+                    int weight = srvRecord.getWeight();
+
+                    SRVRecord r;
+                    try {
+                        r = new SRVRecord(host, port, priority, weight);
+                    } catch (Exception e) {
+                        continue;
+                    }
+                    res.add(r);
+                }
+            }
+
+        } catch (Exception e) {
+        }
+        return res;
+    }
+}