pgoldstein 2002/08/15 14:14:53
Modified: src/java/org/apache/james/dnsserver DNSServer.java
Added: src/java/org/apache/james/dnsserver package.html
Log:
Added extensive commenting.
Corrected a minor bug that hardcoded the type of an internal lookup to MX.
Renamed local variable to differ in name from an instance variable to avoid
confusion.
Revision Changes Path
1.8 +87 -14 jakarta-james/src/java/org/apache/james/dnsserver/DNSServer.java
Index: DNSServer.java
===================================================================
RCS file:
/home/cvs/jakarta-james/src/java/org/apache/james/dnsserver/DNSServer.java,v
retrieving revision 1.7
retrieving revision 1.8
diff -u -r1.7 -r1.8
--- DNSServer.java 7 Aug 2002 23:30:35 -0000 1.7
+++ DNSServer.java 15 Aug 2002 21:14:53 -0000 1.8
@@ -19,6 +19,9 @@
import java.util.*;
/**
+ * Provides DNS client functionality to components running
+ * inside James
+ *
* @version 1.0.0, 18/06/2000
* @author Serge Knystautas <[EMAIL PROTECTED]>
*/
@@ -27,22 +30,44 @@
implements Configurable, Initializable,
org.apache.james.services.DNSServer {
+ /**
+ * A resolver instance used to retrieve DNS records. This
+ * is a reference to a third party library object.
+ */
private Resolver resolver;
+
+ /**
+ * A TTL cache of results received from the DNS server. This
+ * is a reference to a third party library object.
+ */
private Cache cache;
+
+ /**
+ * Whether the DNS response is required to be authoritative
+ */
private byte dnsCredibility;
- private Collection servers = new Vector();
+ /**
+ * The DNS servers to be used by this component
+ */
+ private Collection dnsServers = new Vector();
+
+ /**
+ * Pass the <code>Configuration</code> to the instance.
+ *
+ * @param configuration the class configurations.
+ * @throws ConfigurationException if an error occurs
+ */
public void configure( final Configuration configuration )
throws ConfigurationException {
- // Get this servers that this service will use for lookups
+ // Get the DNS servers that this service will use for lookups
final Configuration serversConfiguration = configuration.getChild(
"servers" );
final Configuration[] serverConfigurations =
serversConfiguration.getChildren( "server" );
- for ( int i = 0; i < serverConfigurations.length; i++ )
- {
- servers.add( serverConfigurations[ i ].getValue() );
+ for ( int i = 0; i < serverConfigurations.length; i++ ) {
+ dnsServers.add( serverConfigurations[ i ].getValue() );
}
final boolean authoritative =
@@ -50,38 +75,64 @@
dnsCredibility = authoritative ? Credibility.AUTH_ANSWER :
Credibility.NONAUTH_ANSWER;
}
+ /**
+ * Initialize the component. Initialization includes
+ * allocating any resources required throughout the
+ * components lifecycle.
+ *
+ * @throws Exception if an error occurs
+ */
public void initialize()
throws Exception {
getLogger().info("DNSServer init...");
- if (servers.isEmpty()) {
+ // If no DNS servers were configured, default to local host
+ if (dnsServers.isEmpty()) {
try {
- servers.add( InetAddress.getLocalHost().getHostName() );
+ dnsServers.add( InetAddress.getLocalHost().getHostName() );
} catch ( UnknownHostException ue ) {
- servers.add( "127.0.0.1" );
+ dnsServers.add( "127.0.0.1" );
}
}
if (getLogger().isInfoEnabled()) {
- for (Iterator i = servers.iterator(); i.hasNext(); ) {
- getLogger().info("DNS Servers is: " + i.next());
+ for (Iterator i = dnsServers.iterator(); i.hasNext(); ) {
+ getLogger().info("DNS Server is: " + i.next());
}
}
//Create the extended resolver...
- final String serversArray[] = (String[])servers.toArray(new String[0]);
- resolver = new ExtendedResolver( serversArray );
+ final String serversArray[] = (String[])dnsServers.toArray(new String[0]);
+ try {
+ resolver = new ExtendedResolver( serversArray );
+ } catch (UnknownHostException uhe) {
+ getLogger().fatalError("DNS service could not be initialized. The DNS
servers specified are not recognized hosts.", uhe);
+ throw uhe;
+ }
cache = new Cache (DClass.IN);
getLogger().info("DNSServer ...init end");
}
+ /**
+ * <p>Return a prioritized list of MX records
+ * obtained from the server.</p>
+ *
+ * <p>TODO: This should actually return a List, not
+ * a Collection.</p>
+ *
+ * @param the domain name to look up
+ *
+ * @return a list of MX records corresponding to
+ * this mail domain name
+ */
public Collection findMXRecords(String hostname) {
Record answers[] = lookup(hostname, Type.MX);
- Collection servers = new Vector ();
+ // TODO: Determine why this collection is synchronized
+ Collection servers = new Vector();
try {
if (answers == null) {
return servers;
@@ -92,6 +143,9 @@
mxAnswers[i] = (MXRecord)answers[i];
}
+ // TODO: Convert this to a static class instance
+ // No need to pay the object creation cost
+ // on each call
Comparator prioritySort = new Comparator () {
public int compare (Object a, Object b) {
MXRecord ma = (MXRecord)a;
@@ -114,15 +168,34 @@
InetAddress.getByName(hostname);
servers.add(hostname);
} catch (UnknownHostException uhe) {
+ // The original domain name is not a valid host,
+ // so we can't add it to the server list. In this
+ // case we return an empty list of servers
}
}
}
}
+ /**
+ * Looks up DNS records of the specified type for the specified name.
+ *
+ * This method is a public wrapper for the private implementation
+ * method
+ *
+ * @param name the name of the host to be looked up
+ * @param type the type of record desired
+ */
public Record[] lookup(String name, short type) {
return rawDNSLookup(name,false,type);
}
+ /**
+ * Looks up DNS records of the specified type for the specified name
+ *
+ * @param name the name of the host to be looked up
+ * @param querysent whether the query has already been sent to the DNS servers
+ * @param type the type of record desired
+ */
private Record[] rawDNSLookup(String namestr, boolean querysent, short type) {
Name name = new Name(namestr);
short dclass = DClass.IN;
@@ -176,7 +249,7 @@
return null;
}
- return rawDNSLookup(namestr, true, Type.MX);
+ return rawDNSLookup(namestr, true, type);
}
return answers;
1.1 jakarta-james/src/java/org/apache/james/dnsserver/package.html
Index: package.html
===================================================================
<body>
Provides classes implementing simple DNS facilities for James
</body>
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