nbtaddress.java

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/* jcifs smb client library in Java
 * Copyright (C) 2000  "Michael B. Allen" <jcifs at samba dot org>
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package jcifs.netbios;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.net.SocketException;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.HashMap;
import jcifs.Config;
import jcifs.util.Hexdump;

/**
 * This class represents a NetBIOS over TCP/IP address. Under normal
 * conditions, users of jCIFS need not be concerned with this class as
 * name resolution and session services are handled internally by the smb package.
 * 
 * <p> Applications can use the methods <code>getLocalHost</code>,
 * <code>getByName</code>, and
 * <code>getAllByAddress</code> to create a new NbtAddress instance. This
 * class is symmetric with {@link java.net.InetAddress}.
 *
 * <p><b>About NetBIOS:</b> The NetBIOS name
 * service is a dynamic distributed service that allows hosts to resolve
 * names by broadcasting a query, directing queries to a server such as
 * Samba or WINS. NetBIOS is currently the primary networking layer for
 * providing name service, datagram service, and session service to the
 * Microsoft Windows platform. A NetBIOS name can be 15 characters long
 * and hosts usually registers several names on the network. From a
 * Windows command prompt you can see
 * what names a host registers with the nbtstat command.
 * <p><blockquote><pre>
 * C:\>nbtstat -a 192.168.1.15
 * 
 *        NetBIOS Remote Machine Name Table
 * 
 *    Name               Type         Status
 * ---------------------------------------------
 * JMORRIS2        <00>  UNIQUE      Registered
 * BILLING-NY      <00>  GROUP       Registered
 * JMORRIS2        <03>  UNIQUE      Registered
 * JMORRIS2        <20>  UNIQUE      Registered
 * BILLING-NY      <1E>  GROUP       Registered
 * JMORRIS         <03>  UNIQUE      Registered
 * 
 * MAC Address = 00-B0-34-21-FA-3B
 * </blockquote></pre>
 * <p> The hostname of this machine is <code>JMORRIS2</code>. It is
 * a member of the group(a.k.a workgroup and domain) <code>BILLING-NY</code>. To
 * obtain an {@link java.net.InetAddress} for a host one might do:
 *
 * <pre>
 *   InetAddress addr = NbtAddress.getByName( "jmorris2" ).getInetAddress();
 * </pre>
 * <p>From a UNIX platform with Samba installed you can perform similar
 * diagnostics using the <code>nmblookup</code> utility.
 *
 * @author    Michael B. Allen
 * @see       java.net.InetAddress
 * @since     jcifs-0.1
 */ 

public final class NbtAddress {

/*
 * This is a special name that means all hosts. If you wish to find all hosts
 * on a network querying a workgroup group name is the preferred method.
 */ 

    static final String ANY_HOSTS_NAME = "*\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000";

/** 
 * This is a special name for querying the master browser that serves the
 * list of hosts found in "Network Neighborhood".
 */ 

    public static final String MASTER_BROWSER_NAME = "\u0001\u0002__MSBROWSE__\u0002";

/**
 * A special generic name specified when connecting to a host for which
 * a name is not known. Not all servers respond to this name.
 */

    public static final String SMBSERVER_NAME = "*SMBSERVER     ";

/** 
 * A B node only broadcasts name queries. This is the default if a
 * nameserver such as WINS or Samba is not specified.
 */ 

    public static final int B_NODE = 0;

/**
 * A Point-to-Point node, or P node, unicasts queries to a nameserver
 * only. Natrually the <code>jcifs.netbios.nameserver</code> property must
 * be set.
 */

    public static final int P_NODE = 1;

/** 
 * Try Broadcast queries first, then try to resolve the name using the
 * nameserver.
 */

    public static final int M_NODE = 2;

/** 
 * A Hybrid node tries to resolve a name using the nameserver first. If
 * that fails use the broadcast address. This is the default if a nameserver
 * is provided. This is the behavior of Microsoft Windows machines.
 */ 

    public static final int H_NODE = 3;

    static final InetAddress[] NBNS = Config.getInetAddressArray( "jcifs.netbios.wins", ",", new InetAddress[0] );

    /* Construct the shared static client object that will
     * conduct all encoding and decoding of NetBIOS name service
     * messages as well as socket IO in a synchronized fashon.
     */

    private static final NameServiceClient CLIENT = new NameServiceClient();

    private static final int DEFAULT_CACHE_POLICY = 30;
    private static final int CACHE_POLICY = Config.getInt( "jcifs.netbios.cachePolicy", DEFAULT_CACHE_POLICY );
    private static final int FOREVER = -1;
    private static int nbnsIndex = 0;

    private static final HashMap ADDRESS_CACHE = new HashMap();
    private static final HashMap LOOKUP_TABLE = new HashMap();

    static final Name UNKNOWN_NAME = new Name( "0.0.0.0", 0x00, null );
    static final NbtAddress UNKNOWN_ADDRESS = new NbtAddress( UNKNOWN_NAME, 0, false, B_NODE );
    static final byte[] UNKNOWN_MAC_ADDRESS = new byte[] {
        (byte)0x00, (byte)0x00, (byte)0x00,
        (byte)0x00, (byte)0x00, (byte)0x00
    };

    static final class CacheEntry {
        Name hostName;
        NbtAddress address;
        long expiration;

        CacheEntry( Name hostName, NbtAddress address, long expiration ) {
            this.hostName = hostName;
            this.address = address;
            this.expiration = expiration;
        }
    }

    static NbtAddress localhost;

    static {
        InetAddress localInetAddress;
        String localHostname;
        Name localName;

        /* Create an address to represent failed lookups and cache forever.
         */

        ADDRESS_CACHE.put( UNKNOWN_NAME, new CacheEntry( UNKNOWN_NAME, UNKNOWN_ADDRESS, FOREVER ));

        /* Determine the InetAddress of the local interface
         * if one was not specified.
         */
        localInetAddress = CLIENT.laddr;
        if( localInetAddress == null ) {
            try {
                localInetAddress = InetAddress.getLocalHost();
            } catch( UnknownHostException uhe ) {
            }
        }

        /* If a local hostname was not provided a name like
         * JCIFS34_172_A6 will be dynamically generated for the
         * client. This is primarily (exclusively?) used as a
         * CallingName during session establishment.
         */
        localHostname = Config.getProperty( "jcifs.netbios.hostname", null );
        if( localHostname == null || localHostname.length() == 0 ) {
            byte[] addr = localInetAddress.getAddress();
            localHostname = "JCIFS" +
                    ( addr[2] & 0xFF ) + "_" +
                    ( addr[3] & 0xFF ) + "_" +
                    Hexdump.toHexString( (int)( Math.random() * (double)0xFF ), 2 );
        }

        /* Create an NbtAddress for the local interface with
         * the name deduced above possibly with scope applied and
         * cache it forever.
         */
        localName = new Name( localHostname, 0x00,
                            Config.getProperty( "jcifs.netbios.scope", null ));
        localhost = new NbtAddress( localName,
                                    localInetAddress.hashCode(),
                                    false,
                                    B_NODE,
                                    false, false, true, false,
                                    UNKNOWN_MAC_ADDRESS );
        cacheAddress( localName, localhost, FOREVER );
    }

    static void cacheAddress( Name hostName, NbtAddress addr ) {
        if( CACHE_POLICY == 0 ) {
            return;
        }
        long expiration = -1;
        if( CACHE_POLICY != FOREVER ) {
            expiration = System.currentTimeMillis() + CACHE_POLICY * 1000;
        }
        cacheAddress( hostName, addr, expiration );
    }
    static void cacheAddress( Name hostName, NbtAddress addr, long expiration ) {
        if( CACHE_POLICY == 0 ) {
            return;
        }
        synchronized( ADDRESS_CACHE ) {
            CacheEntry entry = (CacheEntry)ADDRESS_CACHE.get( hostName );
            if( entry == null ) {
                entry = new CacheEntry( hostName, addr, expiration );
                ADDRESS_CACHE.put( hostName, entry );
            } else {
                entry.address = addr;
                entry.expiration = expiration;
            }
        }
    }
    static void cacheAddressArray( NbtAddress[] addrs ) {
        if( CACHE_POLICY == 0 ) {
            return;
        }
        long expiration = -1;
        if( CACHE_POLICY != FOREVER ) {
            expiration = System.currentTimeMillis() + CACHE_POLICY * 1000;
        }
        synchronized( ADDRESS_CACHE ) {
            for( int i = 0; i < addrs.length; i++ ) {
                CacheEntry entry = (CacheEntry)ADDRESS_CACHE.get( addrs[i].hostName );
                if( entry == null ) {
                    entry = new CacheEntry( addrs[i].hostName, addrs[i], expiration );
                    ADDRESS_CACHE.put( addrs[i].hostName, entry );
                } else {
                    entry.address = addrs[i];
                    entry.expiration = expiration;
                }
            }
        }
    }
    static NbtAddress getCachedAddress( Name hostName ) {
        if( CACHE_POLICY == 0 ) {
            return null;
        }
        synchronized( ADDRESS_CACHE ) {
            CacheEntry entry = (CacheEntry)ADDRESS_CACHE.get( hostName );
            if( entry != null && entry.expiration < System.currentTimeMillis() &&
                                                entry.expiration >= 0 ) {
                entry = null;
            }
            return entry != null ? entry.address : null;
        }
    }

    static NbtAddress doNameQuery( Name name, InetAddress svr )
                                                    throws UnknownHostException {
        NbtAddress addr;

        if( name.hexCode == 0x1d && svr == null ) {
            svr = CLIENT.baddr; // bit of a hack but saves a lookup
        }
        name.srcHashCode = svr != null ? svr.hashCode() : 0;
        addr = getCachedAddress( name );