506 lines
18 KiB
Java
506 lines
18 KiB
Java
/*
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* Copyright (c) 2000, 2022, Oracle and/or its affiliates. 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. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package sun.net.spi.nameservice.dns;
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import java.lang.ref.SoftReference;
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import java.net.InetAddress;
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import java.net.UnknownHostException;
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import javax.naming.*;
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import javax.naming.directory.*;
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import javax.naming.spi.NamingManager;
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import java.util.*;
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import sun.net.util.IPAddressUtil;
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import sun.net.dns.ResolverConfiguration;
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import sun.net.spi.nameservice.*;
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import java.security.AccessController;
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import sun.security.action.*;
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/*
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* A name service provider based on JNDI-DNS.
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*/
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public final class DNSNameService implements NameService {
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// List of domains specified by property
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private LinkedList<String> domainList = null;
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// JNDI-DNS URL for name servers specified via property
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private String nameProviderUrl = null;
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// Per-thread soft cache of the last temporary context
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private static ThreadLocal<SoftReference<ThreadContext>> contextRef =
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new ThreadLocal<>();
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// Simple class to encapsulate the temporary context
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private static class ThreadContext {
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private DirContext dirCtxt;
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private List<String> nsList;
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public ThreadContext(DirContext dirCtxt, List<String> nsList) {
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this.dirCtxt = dirCtxt;
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this.nsList = nsList;
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}
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public DirContext dirContext() {
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return dirCtxt;
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}
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public List<String> nameservers() {
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return nsList;
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}
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}
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// Returns a per-thread DirContext
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private DirContext getTemporaryContext() throws NamingException {
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SoftReference<ThreadContext> ref = contextRef.get();
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ThreadContext thrCtxt = null;
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List<String> nsList = null;
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// if no property specified we need to obtain the list of servers
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//
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if (nameProviderUrl == null)
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nsList = ResolverConfiguration.open().nameservers();
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// if soft reference hasn't been gc'ed no property has been
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// specified then we need to check if the DNS configuration
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// has changed.
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//
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if ((ref != null) && ((thrCtxt = ref.get()) != null)) {
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if (nameProviderUrl == null) {
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if (!thrCtxt.nameservers().equals(nsList)) {
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// DNS configuration has changed
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thrCtxt = null;
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}
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}
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}
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// new thread context needs to be created
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if (thrCtxt == null) {
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final Hashtable<String,Object> env = new Hashtable<>();
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env.put("java.naming.factory.initial",
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"com.sun.jndi.dns.DnsContextFactory");
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// If no nameservers property specified we create provider URL
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// based on system configured name servers
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//
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String provUrl = nameProviderUrl;
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if (provUrl == null) {
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provUrl = createProviderURL(nsList);
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if (provUrl.length() == 0) {
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throw new RuntimeException("bad nameserver configuration");
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}
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}
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env.put("java.naming.provider.url", provUrl);
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// Need to create directory context in privileged block
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// as JNDI-DNS needs to resolve the name servers.
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//
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DirContext dirCtxt;
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try {
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dirCtxt = java.security.AccessController.doPrivileged(
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new java.security.PrivilegedExceptionAction<DirContext>() {
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public DirContext run() throws NamingException {
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// Create the DNS context using NamingManager rather than using
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// the initial context constructor. This avoids having the initial
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// context constructor call itself.
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Context ctx = NamingManager.getInitialContext(env);
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if (!(ctx instanceof DirContext)) {
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return null; // cannot create a DNS context
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}
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return (DirContext)ctx;
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}
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});
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} catch (java.security.PrivilegedActionException pae) {
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throw (NamingException)pae.getException();
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}
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// create new soft reference to our thread context
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//
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thrCtxt = new ThreadContext(dirCtxt, nsList);
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contextRef.set(new SoftReference<ThreadContext>(thrCtxt));
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}
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return thrCtxt.dirContext();
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}
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/**
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* Resolves the specified entry in DNS.
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*
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* Canonical name records are recursively resolved (to a maximum
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* of 5 to avoid performance hit and potential CNAME loops).
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*
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* @param ctx JNDI directory context
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* @param name name to resolve
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* @param ids record types to search
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* @param depth call depth - pass as 0.
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*
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* @return array list with results (will have at least on entry)
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*
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* @throws UnknownHostException if lookup fails or other error.
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*/
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private ArrayList<String> resolve(final DirContext ctx, final String name,
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final String[] ids, int depth)
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throws UnknownHostException
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{
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ArrayList<String> results = new ArrayList<>();
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Attributes attrs;
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// do the query
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try {
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attrs = java.security.AccessController.doPrivileged(
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new java.security.PrivilegedExceptionAction<Attributes>() {
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public Attributes run() throws NamingException {
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return ctx.getAttributes(name, ids);
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}
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});
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} catch (java.security.PrivilegedActionException pae) {
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throw new UnknownHostException(pae.getException().getMessage());
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}
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// non-requested type returned so enumeration is empty
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NamingEnumeration<? extends Attribute> ne = attrs.getAll();
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if (!ne.hasMoreElements()) {
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throw new UnknownHostException("DNS record not found");
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}
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// iterate through the returned attributes
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UnknownHostException uhe = null;
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try {
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while (ne.hasMoreElements()) {
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Attribute attr = ne.next();
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String attrID = attr.getID();
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for (NamingEnumeration<?> e = attr.getAll(); e.hasMoreElements();) {
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String addr = (String)e.next();
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// for canoncical name records do recursive lookup
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// - also check for CNAME loops to avoid stack overflow
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if (attrID.equals("CNAME")) {
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if (depth > 4) {
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throw new UnknownHostException(name + ": possible CNAME loop");
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}
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try {
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results.addAll(resolve(ctx, addr, ids, depth+1));
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} catch (UnknownHostException x) {
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// canonical name can't be resolved.
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if (uhe == null)
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uhe = x;
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}
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} else {
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results.add(addr);
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}
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}
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}
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} catch (NamingException nx) {
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throw new UnknownHostException(nx.getMessage());
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}
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// pending exception as canonical name could not be resolved.
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if (results.isEmpty() && uhe != null) {
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throw uhe;
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}
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return results;
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}
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public DNSNameService() throws Exception {
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// default domain
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String domain = AccessController.doPrivileged(
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new GetPropertyAction("sun.net.spi.nameservice.domain"));
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if (domain != null && domain.length() > 0) {
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domainList = new LinkedList<String>();
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domainList.add(domain);
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}
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// name servers
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String nameservers = AccessController.doPrivileged(
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new GetPropertyAction("sun.net.spi.nameservice.nameservers"));
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if (nameservers != null && nameservers.length() > 0) {
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nameProviderUrl = createProviderURL(nameservers);
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if (nameProviderUrl.length() == 0) {
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throw new RuntimeException("malformed nameservers property");
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}
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} else {
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// no property specified so check host DNS resolver configured
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// with at least one nameserver in dotted notation.
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//
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List<String> nsList = ResolverConfiguration.open().nameservers();
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if (nsList.isEmpty()) {
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throw new RuntimeException("no nameservers provided");
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}
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boolean found = false;
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for (String addr: nsList) {
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if (IPAddressUtil.isIPv4LiteralAddress(addr) ||
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IPAddressUtil.isIPv6LiteralAddress(addr)) {
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found = true;
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break;
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}
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}
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if (!found) {
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throw new RuntimeException("bad nameserver configuration");
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}
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}
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}
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public InetAddress[] lookupAllHostAddr(String host) throws UnknownHostException {
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// DNS records that we search for
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String[] ids = {"A", "AAAA", "CNAME"};
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// first get directory context
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DirContext ctx;
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try {
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ctx = getTemporaryContext();
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} catch (NamingException nx) {
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throw new Error(nx);
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}
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ArrayList<String> results = null;
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UnknownHostException uhe = null;
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// If host already contains a domain name then just look it up
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if (host.indexOf('.') >= 0) {
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try {
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results = resolve(ctx, host, ids, 0);
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} catch (UnknownHostException x) {
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uhe = x;
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}
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}
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// Here we try to resolve the host using the domain suffix or
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// the domain suffix search list. If the host cannot be resolved
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// using the domain suffix then we attempt devolution of
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// the suffix - eg: if we are searching for "foo" and our
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// domain suffix is "eng.sun.com" we will try to resolve
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// "foo.eng.sun.com" and "foo.sun.com".
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// It's not normal to attempt devolation with domains on the
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// domain suffix search list - however as ResolverConfiguration
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// doesn't distinguish domain or search list in the list it
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// returns we approximate by doing devolution on the domain
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// suffix if the list has one entry.
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if (results == null) {
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List<String> searchList = null;
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Iterator<String> i;
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boolean usingSearchList = false;
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if (domainList != null) {
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i = domainList.iterator();
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} else {
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searchList = ResolverConfiguration.open().searchlist();
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if (searchList.size() > 1) {
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usingSearchList = true;
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}
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i = searchList.iterator();
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}
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// iterator through each domain suffix
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while (i.hasNext()) {
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String parentDomain = i.next();
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int start = 0;
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while ((start = parentDomain.indexOf(".")) != -1
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&& start < parentDomain.length() -1) {
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try {
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results = resolve(ctx, host+"."+parentDomain, ids, 0);
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break;
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} catch (UnknownHostException x) {
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uhe = x;
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if (usingSearchList) {
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break;
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}
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// devolve
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parentDomain = parentDomain.substring(start+1);
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}
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}
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if (results != null) {
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break;
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}
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}
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}
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// finally try the host if it doesn't have a domain name
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if (results == null && (host.indexOf('.') < 0)) {
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results = resolve(ctx, host, ids, 0);
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}
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// if not found then throw the (last) exception thrown.
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if (results == null) {
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assert uhe != null;
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throw uhe;
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}
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/**
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* Convert the array list into a byte aray list - this
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* filters out any invalid IPv4/IPv6 addresses.
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*/
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assert results.size() > 0;
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InetAddress[] addrs = new InetAddress[results.size()];
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int count = 0;
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for (int i=0; i<results.size(); i++) {
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String addrString = results.get(i);
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byte[] addr = null;
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try {
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addr = IPAddressUtil.validateNumericFormatV4(addrString);
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} catch (IllegalArgumentException ignored) {
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}
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if (addr == null) {
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addr = IPAddressUtil.textToNumericFormatV6(addrString);
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}
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if (addr != null) {
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addrs[count++] = InetAddress.getByAddress(host, addr);
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}
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}
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/**
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* If addresses are filtered then we need to resize the
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* array. Additionally if all addresses are filtered then
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* we throw an exception.
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*/
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if (count == 0) {
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throw new UnknownHostException(host + ": no valid DNS records");
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}
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if (count < results.size()) {
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InetAddress[] tmp = new InetAddress[count];
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for (int i=0; i<count; i++) {
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tmp[i] = addrs[i];
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}
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addrs = tmp;
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}
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return addrs;
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}
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/**
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* Reverse lookup code. I.E: find a host name from an IP address.
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* IPv4 addresses are mapped in the IN-ADDR.ARPA. top domain, while
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* IPv6 addresses can be in IP6.ARPA or IP6.INT.
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* In both cases the address has to be converted into a dotted form.
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*/
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public String getHostByAddr(byte[] addr) throws UnknownHostException {
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String host = null;
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try {
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String literalip = "";
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String[] ids = { "PTR" };
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DirContext ctx;
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ArrayList<String> results = null;
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try {
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ctx = getTemporaryContext();
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} catch (NamingException nx) {
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throw new Error(nx);
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}
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if (addr.length == 4) { // IPv4 Address
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for (int i = addr.length-1; i >= 0; i--) {
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literalip += (addr[i] & 0xff) +".";
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}
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literalip += "IN-ADDR.ARPA.";
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results = resolve(ctx, literalip, ids, 0);
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host = results.get(0);
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} else if (addr.length == 16) { // IPv6 Address
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/**
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* Because RFC 3152 changed the root domain name for reverse
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* lookups from IP6.INT. to IP6.ARPA., we need to check
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* both. I.E. first the new one, IP6.ARPA, then if it fails
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* the older one, IP6.INT
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*/
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for (int i = addr.length-1; i >= 0; i--) {
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literalip += Integer.toHexString((addr[i] & 0x0f)) +"."
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+Integer.toHexString((addr[i] & 0xf0) >> 4) +".";
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}
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String ip6lit = literalip + "IP6.ARPA.";
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try {
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results = resolve(ctx, ip6lit, ids, 0);
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host = results.get(0);
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} catch (UnknownHostException e) {
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host = null;
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}
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if (host == null) {
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// IP6.ARPA lookup failed, let's try the older IP6.INT
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ip6lit = literalip + "IP6.INT.";
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results = resolve(ctx, ip6lit, ids, 0);
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host = results.get(0);
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}
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}
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} catch (Exception e) {
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throw new UnknownHostException(e.getMessage());
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}
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// Either we couldn't find it or the address was neither IPv4 or IPv6
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if (host == null)
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throw new UnknownHostException();
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// remove trailing dot
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if (host.endsWith(".")) {
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host = host.substring(0, host.length() - 1);
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}
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return host;
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}
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// ---------
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private static void appendIfLiteralAddress(String addr, StringBuffer sb) {
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if (IPAddressUtil.isIPv4LiteralAddress(addr)) {
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sb.append("dns://" + addr + " ");
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} else {
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if (IPAddressUtil.isIPv6LiteralAddress(addr)) {
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sb.append("dns://[" + addr + "] ");
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}
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}
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}
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/*
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* @return String containing the JNDI-DNS provider URL
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* corresponding to the supplied List of nameservers.
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*/
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private static String createProviderURL(List<String> nsList) {
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StringBuffer sb = new StringBuffer();
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for (String s: nsList) {
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appendIfLiteralAddress(s, sb);
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}
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return sb.toString();
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}
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/*
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* @return String containing the JNDI-DNS provider URL
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* corresponding to the list of nameservers
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* contained in the provided str.
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*/
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private static String createProviderURL(String str) {
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StringBuffer sb = new StringBuffer();
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StringTokenizer st = new StringTokenizer(str, ",");
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while (st.hasMoreTokens()) {
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appendIfLiteralAddress(st.nextToken(), sb);
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}
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return sb.toString();
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}
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}
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