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;
+    }
+}

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

@@ -0,0 +1,24 @@
+/**
+ * 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.List;
+
+public abstract class DNSResolver {
+
+    public abstract List<SRVRecord> lookupSRVRecords(String name);
+
+}

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

@@ -0,0 +1,93 @@
+/**
+ * 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;
+
+public class HostAddress {
+    private String fqdn;
+    private int port;
+    private Exception exception;
+
+    /**
+     * Creates a new HostAddress with the given FQDN. The port will be set to the default XMPP client port: 5222
+     * 
+     * @param fqdn
+     * @throws IllegalArgumentException
+     */
+    public HostAddress(String fqdn) throws IllegalArgumentException {
+        if (fqdn == null)
+            throw new IllegalArgumentException("FQDN is null");
+        if (fqdn.charAt(fqdn.length() - 1) == '.') {
+            this.fqdn = fqdn.substring(0, fqdn.length() - 1);
+        }
+        else {
+            this.fqdn = fqdn;
+        }
+        // Set port to the default port for XMPP client communication
+        this.port = 5222;
+    }
+
+    public HostAddress(String fqdn, int port) throws IllegalArgumentException {
+        this(fqdn);
+        if (port < 0 || port > 65535)
+            throw new IllegalArgumentException(
+                    "DNS SRV records weight must be a 16-bit unsiged integer (i.e. between 0-65535. Port was: " + port);
+
+        this.port = port;
+    }
+
+    public String getFQDN() {
+        return fqdn;
+    }
+
+    public int getPort() {
+        return port;
+    }
+
+    public void setException(Exception e) {
+        this.exception = e;
+    }
+
+    public String toString() {
+        return fqdn + ":" + port;
+    }
+
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (!(o instanceof HostAddress)) {
+            return false;
+        }
+
+        final HostAddress address = (HostAddress) o;
+
+        if (!fqdn.equals(address.fqdn)) {
+            return false;
+        }
+        return port == address.port;
+    }
+
+    public String getErrorMessage() {
+        String error;
+        if (exception == null) {
+            error = "No error logged";
+        }
+        else {
+            error = exception.getMessage();
+        }
+        return toString() + " Exception: " + error;
+    }
+}

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

@@ -0,0 +1,99 @@
+/**
+ * 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.Hashtable;
+import java.util.List;
+
+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 org.jivesoftware.smack.util.DNSUtil;
+
+/**
+ * A DNS resolver (mostly for SRV records), which makes use of the API provided in the javax.* namepsace.
+ * 
+ * @author Florian Schmaus
+ *
+ */
+public class JavaxResolver extends DNSResolver {
+    
+    private static JavaxResolver instance;
+    private static DirContext dirContext;
+    
+    static {
+        try {
+            Hashtable<String, String> env = new Hashtable<String, String>();
+            env.put("java.naming.factory.initial", "com.sun.jndi.dns.DnsContextFactory");
+            dirContext = new InitialDirContext(env);
+        } catch (Exception e) {
+            // Ignore.
+        }
+
+        // Try to set this DNS resolver as primary one
+        DNSUtil.setDNSResolver(maybeGetInstance());
+    }
+    
+    private JavaxResolver() {
+        
+    }
+    
+    public static DNSResolver maybeGetInstance() {
+        if (instance == null && isSupported()) {
+            instance = new JavaxResolver();
+        }
+        return instance;
+    }
+    
+    public static boolean isSupported() {
+        return dirContext != null;
+    }
+
+    @Override
+    public List<SRVRecord> lookupSRVRecords(String name) {
+        List<SRVRecord> res = new ArrayList<SRVRecord>();
+        
+        try {
+            Attributes dnsLookup = dirContext.getAttributes(name, new String[]{"SRV"});
+            Attribute srvAttribute = dnsLookup.get("SRV");
+            @SuppressWarnings("unchecked")
+            NamingEnumeration<String> srvRecords = (NamingEnumeration<String>) srvAttribute.getAll();
+            while (srvRecords.hasMore()) {
+                String srvRecordString = srvRecords.next();
+                String[] srvRecordEntries = srvRecordString.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];
+
+                SRVRecord srvRecord;
+                try {
+                    srvRecord = new SRVRecord(host, port, priority, weight);
+                } catch (Exception e) {
+                    continue;
+                }
+                res.add(srvRecord);
+            }
+        } catch (Exception e) {
+            
+        }
+        return res;
+    }
+}

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

@@ -0,0 +1,77 @@
+/**
+ * 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;
+
+/**
+ * @see <a href="http://tools.ietf.org/html/rfc2782>RFC 2782: A DNS RR for specifying the location of services (DNS
+ * SRV)<a>
+ * @author Florian Schmaus
+ * 
+ */
+public class SRVRecord extends HostAddress implements Comparable<SRVRecord> {
+    
+    private int weight;
+    private int priority;
+    
+    /**
+     * Create a new SRVRecord
+     * 
+     * @param fqdn
+     * @param port
+     * @param priority
+     * @param weight
+     * @throws IllegalArgumentException
+     */
+    public SRVRecord(String fqdn, int port, int priority, int weight) throws IllegalArgumentException {
+        super(fqdn, port);
+        if (weight < 0 || weight > 65535)
+            throw new IllegalArgumentException(
+                    "DNS SRV records weight must be a 16-bit unsiged integer (i.e. between 0-65535. Weight was: "
+                            + weight);
+
+        if (priority < 0 || priority > 65535)
+            throw new IllegalArgumentException(
+                    "DNS SRV records priority must be a 16-bit unsiged integer (i.e. between 0-65535. Priority was: "
+                            + priority);
+
+        this.priority = priority;
+        this.weight = weight;
+
+    }
+    
+    public int getPriority() {
+        return priority;
+    }
+    
+    public int getWeight() {
+        return weight;
+    }
+
+    public int compareTo(SRVRecord other) {
+        // According to RFC2782,
+        // "[a] client MUST attempt to contact the target host with the lowest-numbered priority it can reach".
+        // This means that a SRV record with a higher priority is 'less' then one with a lower.
+        int res = other.priority - this.priority;
+        if (res == 0) {
+            res = this.weight - other.weight;
+        }
+        return res;
+    }
+
+    public String toString() {
+        return super.toString() + " prio:" + priority + ":w:" + weight;
+    }
+}