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/*
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* Copyright 2000-2004 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Sun designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Sun in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*/
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package com.sun.jndi.dns;
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import java.io.IOException;
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import java.net.DatagramSocket;
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import java.net.DatagramPacket;
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import java.net.InetAddress;
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import java.net.Socket;
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import javax.naming.*;
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import java.util.Collections;
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import java.util.Map;
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import java.util.HashMap;
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import java.util.Set;
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import java.util.HashSet;
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// Some of this code began life as part of sun.javaos.net.DnsClient
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// originally by sritchie@eng 1/96. It was first hacked up for JNDI
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// use by caveh@eng 6/97.
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/**
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* The DnsClient class performs DNS client operations in support of DnsContext.
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*
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*/
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public class DnsClient {
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// DNS packet header field offsets
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private static final int IDENT_OFFSET = 0;
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private static final int FLAGS_OFFSET = 2;
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private static final int NUMQ_OFFSET = 4;
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private static final int NUMANS_OFFSET = 6;
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private static final int NUMAUTH_OFFSET = 8;
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private static final int NUMADD_OFFSET = 10;
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private static final int DNS_HDR_SIZE = 12;
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// DNS response codes
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private static final int NO_ERROR = 0;
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private static final int FORMAT_ERROR = 1;
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private static final int SERVER_FAILURE = 2;
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private static final int NAME_ERROR = 3;
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private static final int NOT_IMPL = 4;
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private static final int REFUSED = 5;
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private static final String[] rcodeDescription = {
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"No error",
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"DNS format error",
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"DNS server failure",
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"DNS name not found",
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"DNS operation not supported",
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"DNS service refused"
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};
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private static final int DEFAULT_PORT = 53;
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private InetAddress[] servers;
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private int[] serverPorts;
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private int timeout; // initial timeout on UDP queries in ms
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private int retries; // number of UDP retries
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private DatagramSocket udpSocket;
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// Requests sent
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private Set<Integer> reqs;
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// Responses received
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private Map<Integer, byte[]> resps;
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//-------------------------------------------------------------------------
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/*
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* Each server is of the form "server[:port]". IPv6 literal host names
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* include delimiting brackets.
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* "timeout" is the initial timeout interval (in ms) for UDP queries,
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* and "retries" gives the number of retries per server.
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*/
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public DnsClient(String[] servers, int timeout, int retries)
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throws NamingException {
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this.timeout = timeout;
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this.retries = retries;
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try {
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udpSocket = new DatagramSocket();
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} catch (java.net.SocketException e) {
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NamingException ne = new ConfigurationException();
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ne.setRootCause(e);
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throw ne;
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}
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this.servers = new InetAddress[servers.length];
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serverPorts = new int[servers.length];
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for (int i = 0; i < servers.length; i++) {
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// Is optional port given?
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int colon = servers[i].indexOf(':',
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servers[i].indexOf(']') + 1);
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serverPorts[i] = (colon < 0)
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? DEFAULT_PORT
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: Integer.parseInt(servers[i].substring(colon + 1));
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String server = (colon < 0)
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? servers[i]
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: servers[i].substring(0, colon);
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try {
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this.servers[i] = InetAddress.getByName(server);
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} catch (java.net.UnknownHostException e) {
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NamingException ne = new ConfigurationException(
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"Unknown DNS server: " + server);
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ne.setRootCause(e);
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throw ne;
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}
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}
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reqs = Collections.synchronizedSet(new HashSet<Integer>());
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resps = Collections.synchronizedMap(new HashMap<Integer, byte[]>());
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}
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protected void finalize() {
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close();
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}
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// A lock to access the request and response queues in tandem.
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private Object queuesLock = new Object();
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public void close() {
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udpSocket.close();
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synchronized (queuesLock) {
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reqs.clear();
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resps.clear();
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}
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}
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private int ident = 0; // used to set the msg ID field
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private Object identLock = new Object();
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/*
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* If recursion is true, recursion is requested on the query.
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* If auth is true, only authoritative responses are accepted; other
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* responses throw NameNotFoundException.
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*/
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ResourceRecords query(DnsName fqdn, int qclass, int qtype,
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boolean recursion, boolean auth)
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throws NamingException {
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int xid;
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synchronized (identLock) {
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ident = 0xFFFF & (ident + 1);
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xid = ident;
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}
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// enqueue the outstanding request
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reqs.add(xid);
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Packet pkt = makeQueryPacket(fqdn, xid, qclass, qtype, recursion);
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Exception caughtException = null;
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boolean[] doNotRetry = new boolean[servers.length];
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//
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// The UDP retry strategy is to try the 1st server, and then
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// each server in order. If no answer, double the timeout
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// and try each server again.
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//
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for (int retry = 0; retry < retries; retry++) {
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// Try each name server.
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for (int i = 0; i < servers.length; i++) {
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if (doNotRetry[i]) {
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continue;
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}
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// send the request packet and wait for a response.
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try {
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if (debug) {
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dprint("SEND ID (" + (retry + 1) + "): " + xid);
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}
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byte[] msg = null;
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msg = doUdpQuery(pkt, servers[i], serverPorts[i],
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retry, xid);
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//
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// If the matching response is not got within the
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// given timeout, check if the response was enqueued
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// by some other thread, if not proceed with the next
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// server or retry.
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//
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if (msg == null) {
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if (resps.size() > 0) {
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msg = lookupResponse(xid);
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}
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if (msg == null) { // try next server or retry
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continue;
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}
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}
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Header hdr = new Header(msg, msg.length);
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if (auth && !hdr.authoritative) {
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caughtException = new NameNotFoundException(
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"DNS response not authoritative");
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doNotRetry[i] = true;
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continue;
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}
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if (hdr.truncated) { // message is truncated -- try TCP
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// Try each server, starting with the one that just
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// provided the truncated message.
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for (int j = 0; j < servers.length; j++) {
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int ij = (i + j) % servers.length;
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if (doNotRetry[ij]) {
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continue;
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}
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try {
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Tcp tcp =
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new Tcp(servers[ij], serverPorts[ij]);
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byte[] msg2;
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try {
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msg2 = doTcpQuery(tcp, pkt);
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} finally {
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tcp.close();
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}
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Header hdr2 = new Header(msg2, msg2.length);
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if (hdr2.query) {
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throw new CommunicationException(
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"DNS error: expecting response");
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}
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checkResponseCode(hdr2);
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if (!auth || hdr2.authoritative) {
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// Got a valid response
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hdr = hdr2;
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msg = msg2;
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break;
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} else {
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doNotRetry[ij] = true;
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}
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} catch (Exception e) {
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// Try next server, or use UDP response
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}
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} // servers
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}
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return new ResourceRecords(msg, msg.length, hdr, false);
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} catch (IOException e) {
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if (debug) {
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dprint("Caught IOException:" + e);
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}
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if (caughtException == null) {
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caughtException = e;
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}
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// Use reflection to allow pre-1.4 compilation.
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// This won't be needed much longer.
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if (e.getClass().getName().equals(
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"java.net.PortUnreachableException")) {
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doNotRetry[i] = true;
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}
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} catch (NameNotFoundException e) {
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throw e;
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} catch (CommunicationException e) {
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if (caughtException == null) {
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caughtException = e;
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}
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} catch (NamingException e) {
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if (caughtException == null) {
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caughtException = e;
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}
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doNotRetry[i] = true;
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}
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} // servers
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} // retries
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reqs.remove(xid);
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if (caughtException instanceof NamingException) {
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throw (NamingException) caughtException;
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}
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// A network timeout or other error occurred.
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NamingException ne = new CommunicationException("DNS error");
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ne.setRootCause(caughtException);
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throw ne;
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}
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ResourceRecords queryZone(DnsName zone, int qclass, boolean recursion)
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throws NamingException {
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int xid;
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synchronized (identLock) {
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ident = 0xFFFF & (ident + 1);
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xid = ident;
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}
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Packet pkt = makeQueryPacket(zone, xid, qclass,
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ResourceRecord.QTYPE_AXFR, recursion);
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Exception caughtException = null;
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// Try each name server.
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for (int i = 0; i < servers.length; i++) {
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try {
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Tcp tcp = new Tcp(servers[i], serverPorts[i]);
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byte[] msg;
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try {
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msg = doTcpQuery(tcp, pkt);
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Header hdr = new Header(msg, msg.length);
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// Check only rcode as per
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// draft-ietf-dnsext-axfr-clarify-04
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checkResponseCode(hdr);
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ResourceRecords rrs =
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new ResourceRecords(msg, msg.length, hdr, true);
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if (rrs.getFirstAnsType() != ResourceRecord.TYPE_SOA) {
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throw new CommunicationException(
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"DNS error: zone xfer doesn't begin with SOA");
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}
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if (rrs.answer.size() == 1 ||
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rrs.getLastAnsType() != ResourceRecord.TYPE_SOA) {
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// The response is split into multiple DNS messages.
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do {
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msg = continueTcpQuery(tcp);
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if (msg == null) {
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throw new CommunicationException(
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"DNS error: incomplete zone transfer");
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}
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hdr = new Header(msg, msg.length);
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checkResponseCode(hdr);
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rrs.add(msg, msg.length, hdr);
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} while (rrs.getLastAnsType() !=
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ResourceRecord.TYPE_SOA);
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}
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// Delete the duplicate SOA record.
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rrs.answer.removeElementAt(rrs.answer.size() - 1);
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return rrs;
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} finally {
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tcp.close();
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}
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} catch (IOException e) {
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caughtException = e;
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} catch (NameNotFoundException e) {
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throw e;
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} catch (NamingException e) {
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caughtException = e;
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}
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}
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if (caughtException instanceof NamingException) {
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throw (NamingException) caughtException;
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}
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NamingException ne = new CommunicationException(
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"DNS error during zone transfer");
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ne.setRootCause(caughtException);
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throw ne;
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}
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/**
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* Tries to retreive an UDP packet matching the given xid
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* received within the timeout.
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* If a packet with different xid is received, the received packet
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* is enqueued with the corresponding xid in 'resps'.
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*/
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private byte[] doUdpQuery(Packet pkt, InetAddress server,
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int port, int retry, int xid)
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385 |
throws IOException, NamingException {
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386 |
|
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int minTimeout = 50; // msec after which there are no retries.
|
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388 |
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389 |
synchronized (udpSocket) {
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390 |
DatagramPacket opkt = new DatagramPacket(
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391 |
pkt.getData(), pkt.length(), server, port);
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|
392 |
DatagramPacket ipkt = new DatagramPacket(new byte[8000], 8000);
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393 |
udpSocket.connect(server, port);
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394 |
int pktTimeout = (timeout * (1 << retry));
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395 |
try {
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396 |
udpSocket.send(opkt);
|
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397 |
|
|
398 |
// timeout remaining after successive 'receive()'
|
|
399 |
int timeoutLeft = pktTimeout;
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400 |
int cnt = 0;
|
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401 |
do {
|
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402 |
if (debug) {
|
|
403 |
cnt++;
|
|
404 |
dprint("Trying RECEIVE(" +
|
|
405 |
cnt + ") retry(" + (retry + 1) +
|
|
406 |
") for:" + xid + " sock-timeout:" +
|
|
407 |
timeoutLeft + " ms.");
|
|
408 |
}
|
|
409 |
udpSocket.setSoTimeout(timeoutLeft);
|
|
410 |
long start = System.currentTimeMillis();
|
|
411 |
udpSocket.receive(ipkt);
|
|
412 |
long end = System.currentTimeMillis();
|
|
413 |
|
|
414 |
byte[] data = new byte[ipkt.getLength()];
|
|
415 |
data = ipkt.getData();
|
|
416 |
if (isMatchResponse(data, xid)) {
|
|
417 |
return data;
|
|
418 |
}
|
|
419 |
timeoutLeft = pktTimeout - ((int) (end - start));
|
|
420 |
} while (timeoutLeft > minTimeout);
|
|
421 |
|
|
422 |
} finally {
|
|
423 |
udpSocket.disconnect();
|
|
424 |
}
|
|
425 |
return null; // no matching packet received within the timeout
|
|
426 |
}
|
|
427 |
}
|
|
428 |
|
|
429 |
/*
|
|
430 |
* Sends a TCP query, and returns the first DNS message in the response.
|
|
431 |
*/
|
|
432 |
private byte[] doTcpQuery(Tcp tcp, Packet pkt) throws IOException {
|
|
433 |
|
|
434 |
int len = pkt.length();
|
|
435 |
// Send 2-byte message length, then send message.
|
|
436 |
tcp.out.write(len >> 8);
|
|
437 |
tcp.out.write(len);
|
|
438 |
tcp.out.write(pkt.getData(), 0, len);
|
|
439 |
tcp.out.flush();
|
|
440 |
|
|
441 |
byte[] msg = continueTcpQuery(tcp);
|
|
442 |
if (msg == null) {
|
|
443 |
throw new IOException("DNS error: no response");
|
|
444 |
}
|
|
445 |
return msg;
|
|
446 |
}
|
|
447 |
|
|
448 |
/*
|
|
449 |
* Returns the next DNS message from the TCP socket, or null on EOF.
|
|
450 |
*/
|
|
451 |
private byte[] continueTcpQuery(Tcp tcp) throws IOException {
|
|
452 |
|
|
453 |
int lenHi = tcp.in.read(); // high-order byte of response length
|
|
454 |
if (lenHi == -1) {
|
|
455 |
return null; // EOF
|
|
456 |
}
|
|
457 |
int lenLo = tcp.in.read(); // low-order byte of response length
|
|
458 |
if (lenLo == -1) {
|
|
459 |
throw new IOException("Corrupted DNS response: bad length");
|
|
460 |
}
|
|
461 |
int len = (lenHi << 8) | lenLo;
|
|
462 |
byte[] msg = new byte[len];
|
|
463 |
int pos = 0; // next unfilled position in msg
|
|
464 |
while (len > 0) {
|
|
465 |
int n = tcp.in.read(msg, pos, len);
|
|
466 |
if (n == -1) {
|
|
467 |
throw new IOException(
|
|
468 |
"Corrupted DNS response: too little data");
|
|
469 |
}
|
|
470 |
len -= n;
|
|
471 |
pos += n;
|
|
472 |
}
|
|
473 |
return msg;
|
|
474 |
}
|
|
475 |
|
|
476 |
private Packet makeQueryPacket(DnsName fqdn, int xid,
|
|
477 |
int qclass, int qtype, boolean recursion) {
|
|
478 |
int qnameLen = fqdn.getOctets();
|
|
479 |
int pktLen = DNS_HDR_SIZE + qnameLen + 4;
|
|
480 |
Packet pkt = new Packet(pktLen);
|
|
481 |
|
|
482 |
short flags = recursion ? Header.RD_BIT : 0;
|
|
483 |
|
|
484 |
pkt.putShort(xid, IDENT_OFFSET);
|
|
485 |
pkt.putShort(flags, FLAGS_OFFSET);
|
|
486 |
pkt.putShort(1, NUMQ_OFFSET);
|
|
487 |
pkt.putShort(0, NUMANS_OFFSET);
|
|
488 |
pkt.putInt(0, NUMAUTH_OFFSET);
|
|
489 |
|
|
490 |
makeQueryName(fqdn, pkt, DNS_HDR_SIZE);
|
|
491 |
pkt.putShort(qtype, DNS_HDR_SIZE + qnameLen);
|
|
492 |
pkt.putShort(qclass, DNS_HDR_SIZE + qnameLen + 2);
|
|
493 |
|
|
494 |
return pkt;
|
|
495 |
}
|
|
496 |
|
|
497 |
// Builds a query name in pkt according to the RFC spec.
|
|
498 |
private void makeQueryName(DnsName fqdn, Packet pkt, int off) {
|
|
499 |
|
|
500 |
// Loop through labels, least-significant first.
|
|
501 |
for (int i = fqdn.size() - 1; i >= 0; i--) {
|
|
502 |
String label = fqdn.get(i);
|
|
503 |
int len = label.length();
|
|
504 |
|
|
505 |
pkt.putByte(len, off++);
|
|
506 |
for (int j = 0; j < len; j++) {
|
|
507 |
pkt.putByte(label.charAt(j), off++);
|
|
508 |
}
|
|
509 |
}
|
|
510 |
if (!fqdn.hasRootLabel()) {
|
|
511 |
pkt.putByte(0, off);
|
|
512 |
}
|
|
513 |
}
|
|
514 |
|
|
515 |
//-------------------------------------------------------------------------
|
|
516 |
|
|
517 |
private byte[] lookupResponse(Integer xid) throws NamingException {
|
|
518 |
//
|
|
519 |
// Check the queued responses: some other thread in between
|
|
520 |
// received the response for this request.
|
|
521 |
//
|
|
522 |
if (debug) {
|
|
523 |
dprint("LOOKUP for: " + xid +
|
|
524 |
"\tResponse Q:" + resps);
|
|
525 |
}
|
|
526 |
byte[] pkt;
|
|
527 |
if ((pkt = (byte[]) resps.get(xid)) != null) {
|
|
528 |
synchronized (queuesLock) {
|
|
529 |
resps.remove(xid);
|
|
530 |
reqs.remove(xid);
|
|
531 |
}
|
|
532 |
checkResponseCode(new Header(pkt, pkt.length));
|
|
533 |
|
|
534 |
if (debug) {
|
|
535 |
dprint("FOUND (" + Thread.currentThread() +
|
|
536 |
") for:" + xid);
|
|
537 |
}
|
|
538 |
}
|
|
539 |
return pkt;
|
|
540 |
}
|
|
541 |
|
|
542 |
/*
|
|
543 |
* Checks the header of an incoming DNS response.
|
|
544 |
* Returns true if it matches the given xid and throws a naming
|
|
545 |
* exception, if appropriate, based on the response code.
|
|
546 |
*/
|
|
547 |
private boolean isMatchResponse(byte[] pkt, int xid)
|
|
548 |
throws NamingException {
|
|
549 |
|
|
550 |
Header hdr = new Header(pkt, pkt.length);
|
|
551 |
if (hdr.query) {
|
|
552 |
throw new CommunicationException("DNS error: expecting response");
|
|
553 |
}
|
|
554 |
|
|
555 |
if (!reqs.contains(xid)) { // already received, ignore the response
|
|
556 |
return false;
|
|
557 |
}
|
|
558 |
|
|
559 |
// common case- the request sent matches the subsequent response read
|
|
560 |
if (hdr.xid == xid) {
|
|
561 |
if (debug) {
|
|
562 |
dprint("XID MATCH:" + xid);
|
|
563 |
}
|
|
564 |
|
|
565 |
// remove the response for the xid if received by some other thread.
|
|
566 |
synchronized (queuesLock) {
|
|
567 |
resps.remove(xid);
|
|
568 |
reqs.remove(xid);
|
|
569 |
}
|
|
570 |
checkResponseCode(hdr);
|
|
571 |
return true;
|
|
572 |
}
|
|
573 |
|
|
574 |
//
|
|
575 |
// xid mis-match: enqueue the response, it may belong to some other
|
|
576 |
// thread that has not yet had a chance to read its response.
|
|
577 |
// enqueue only the first response, responses for retries are ignored.
|
|
578 |
//
|
|
579 |
synchronized (queuesLock) {
|
|
580 |
if (reqs.contains(xid)) { // enqueue only the first response
|
|
581 |
resps.put(xid, pkt);
|
|
582 |
}
|
|
583 |
}
|
|
584 |
|
|
585 |
if (debug) {
|
|
586 |
dprint("NO-MATCH SEND ID:" +
|
|
587 |
xid + " RECVD ID:" + hdr.xid +
|
|
588 |
" Response Q:" + resps +
|
|
589 |
" Reqs size:" + reqs.size());
|
|
590 |
}
|
|
591 |
return false;
|
|
592 |
}
|
|
593 |
|
|
594 |
/*
|
|
595 |
* Throws an exception if appropriate for the response code of a
|
|
596 |
* given header.
|
|
597 |
*/
|
|
598 |
private void checkResponseCode(Header hdr) throws NamingException {
|
|
599 |
|
|
600 |
int rcode = hdr.rcode;
|
|
601 |
if (rcode == NO_ERROR) {
|
|
602 |
return;
|
|
603 |
}
|
|
604 |
String msg = (rcode < rcodeDescription.length)
|
|
605 |
? rcodeDescription[rcode]
|
|
606 |
: "DNS error";
|
|
607 |
msg += " [response code " + rcode + "]";
|
|
608 |
|
|
609 |
switch (rcode) {
|
|
610 |
case SERVER_FAILURE:
|
|
611 |
throw new ServiceUnavailableException(msg);
|
|
612 |
case NAME_ERROR:
|
|
613 |
throw new NameNotFoundException(msg);
|
|
614 |
case NOT_IMPL:
|
|
615 |
case REFUSED:
|
|
616 |
throw new OperationNotSupportedException(msg);
|
|
617 |
case FORMAT_ERROR:
|
|
618 |
default:
|
|
619 |
throw new NamingException(msg);
|
|
620 |
}
|
|
621 |
}
|
|
622 |
|
|
623 |
//-------------------------------------------------------------------------
|
|
624 |
|
|
625 |
private static boolean debug = false;
|
|
626 |
|
|
627 |
public static void setDebug(boolean flag) {
|
|
628 |
debug = flag;
|
|
629 |
}
|
|
630 |
|
|
631 |
private static void dprint(String mess) {
|
|
632 |
if (debug) {
|
|
633 |
System.err.println("DNS: " + mess);
|
|
634 |
}
|
|
635 |
}
|
|
636 |
|
|
637 |
}
|
|
638 |
|
|
639 |
class Tcp {
|
|
640 |
|
|
641 |
private Socket sock;
|
|
642 |
java.io.InputStream in;
|
|
643 |
java.io.OutputStream out;
|
|
644 |
|
|
645 |
Tcp(InetAddress server, int port) throws IOException {
|
|
646 |
sock = new Socket(server, port);
|
|
647 |
sock.setTcpNoDelay(true);
|
|
648 |
out = new java.io.BufferedOutputStream(sock.getOutputStream());
|
|
649 |
in = new java.io.BufferedInputStream(sock.getInputStream());
|
|
650 |
}
|
|
651 |
|
|
652 |
void close() throws IOException {
|
|
653 |
sock.close();
|
|
654 |
}
|
|
655 |
}
|
|
656 |
|
|
657 |
/*
|
|
658 |
* javaos emulation -cj
|
|
659 |
*/
|
|
660 |
class Packet {
|
|
661 |
byte buf[];
|
|
662 |
|
|
663 |
Packet(int len) {
|
|
664 |
buf = new byte[len];
|
|
665 |
}
|
|
666 |
|
|
667 |
Packet(byte data[], int len) {
|
|
668 |
buf = new byte[len];
|
|
669 |
System.arraycopy(data, 0, buf, 0, len);
|
|
670 |
}
|
|
671 |
|
|
672 |
void putInt(int x, int off) {
|
|
673 |
buf[off + 0] = (byte)(x >> 24);
|
|
674 |
buf[off + 1] = (byte)(x >> 16);
|
|
675 |
buf[off + 2] = (byte)(x >> 8);
|
|
676 |
buf[off + 3] = (byte)x;
|
|
677 |
}
|
|
678 |
|
|
679 |
void putShort(int x, int off) {
|
|
680 |
buf[off + 0] = (byte)(x >> 8);
|
|
681 |
buf[off + 1] = (byte)x;
|
|
682 |
}
|
|
683 |
|
|
684 |
void putByte(int x, int off) {
|
|
685 |
buf[off] = (byte)x;
|
|
686 |
}
|
|
687 |
|
|
688 |
void putBytes(byte src[], int src_offset, int dst_offset, int len) {
|
|
689 |
System.arraycopy(src, src_offset, buf, dst_offset, len);
|
|
690 |
}
|
|
691 |
|
|
692 |
int length() {
|
|
693 |
return buf.length;
|
|
694 |
}
|
|
695 |
|
|
696 |
byte[] getData() {
|
|
697 |
return buf;
|
|
698 |
}
|
|
699 |
}
|