--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.dns.client/unix/classes/jdk/dns/conf/DnsResolverConfiguration.java Thu Oct 31 16:16:21 2019 +0000
@@ -0,0 +1,286 @@
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code 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 General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.dns.conf;
+
+import jdk.dns.client.internal.util.ReloadTracker;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+import java.nio.file.Paths;
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+import java.security.PrivilegedExceptionAction;
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.StringTokenizer;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+/*
+ * An implementation of DnsResolverConfiguration for Solaris
+ * and Linux.
+ */
+
+public class DnsResolverConfiguration {
+ // Lock held whilst loading configuration or checking
+ private static final ReadWriteLock LOCK = new ReentrantReadWriteLock();
+
+ //
+ private static String RESOLV_CONF_LOCATION = java.security.AccessController.doPrivileged(
+ (PrivilegedAction<String>) () -> System.getProperty("jdk.dns.client.resolv.conf", "/etc/resolv.conf"));
+ private static final ReloadTracker RESOLVE_CONF_TRACKER;
+
+
+ // Cache timeout (300 seconds) - should be converted into property
+ // or configured as preference in the future.
+ private static final int TIMEOUT = 300_000;
+
+ // Parse /etc/resolv.conf to get the values for a particular
+ // keyword.
+ //
+ private List<String> resolvconf(String keyword,
+ int maxperkeyword,
+ int maxkeywords) {
+ LinkedList<String> ll = new LinkedList<>();
+
+ try {
+ BufferedReader in =
+ new BufferedReader(new FileReader(RESOLV_CONF_LOCATION));
+ String line;
+ while ((line = in.readLine()) != null) {
+ int maxvalues = maxperkeyword;
+ if (line.isEmpty())
+ continue;
+ if (line.charAt(0) == '#' || line.charAt(0) == ';')
+ continue;
+ if (!line.startsWith(keyword))
+ continue;
+ String value = line.substring(keyword.length());
+ if (value.isEmpty())
+ continue;
+ if (value.charAt(0) != ' ' && value.charAt(0) != '\t')
+ continue;
+ StringTokenizer st = new StringTokenizer(value, " \t");
+ while (st.hasMoreTokens()) {
+ String val = st.nextToken();
+ if (val.charAt(0) == '#' || val.charAt(0) == ';') {
+ break;
+ }
+ if ("nameserver".equals(keyword)) {
+ if (val.indexOf(':') >= 0 &&
+ val.indexOf('.') < 0 && // skip for IPv4 literals with port
+ val.indexOf('[') < 0 &&
+ val.indexOf(']') < 0) {
+ // IPv6 literal, in non-BSD-style.
+ val = "[" + val + "]";
+ }
+ }
+ ll.add(val);
+ if (--maxvalues == 0) {
+ break;
+ }
+ }
+ if (--maxkeywords == 0) {
+ break;
+ }
+ }
+ in.close();
+ } catch (IOException ioe) {
+ // problem reading value
+ }
+
+ return Collections.unmodifiableList(ll);
+ }
+
+ private volatile List<String> searchlist = Collections.emptyList();
+ private volatile List<String> nameservers = Collections.emptyList();
+ private volatile String domain = "";
+
+
+ // Load DNS configuration from OS
+ private void loadConfig() {
+ LOCK.readLock().lock();
+ try {
+ var rs = RESOLVE_CONF_TRACKER.getReloadStatus();
+ if (!rs.isReloadNeeded() || !rs.isFileExists()) {
+ return;
+ }
+ } finally {
+ LOCK.readLock().unlock();
+ }
+
+ LOCK.writeLock().lock();
+ try {
+ var rs = RESOLVE_CONF_TRACKER.getReloadStatus();
+ // Check if reload is needed again
+ if (rs.isReloadNeeded()) {
+ if (rs.isFileExists()) {
+ // get the name servers from /etc/resolv.conf
+ nameservers =
+ java.security.AccessController.doPrivileged(
+ (PrivilegedAction<List<String>>) () -> {
+ // typically MAXNS is 3 but we've picked 5 here
+ // to allow for additional servers if required.
+ return resolvconf("nameserver", 1, 5);
+ });
+
+ // get the search list (or domain)
+ searchlist = getSearchList();
+
+ // update the timestamp on the configuration
+ RESOLVE_CONF_TRACKER.updateTimestamps(rs);
+ } else {
+ nameservers = Collections.emptyList();
+ searchlist = Collections.emptyList();
+ }
+ }
+ } finally {
+ LOCK.writeLock().unlock();
+ }
+ }
+
+ // obtain search list or local domain
+ private List<String> getSearchList() {
+
+ List<String> sl;
+
+ // first try the search keyword in /etc/resolv.conf
+
+ /* run */
+ sl = java.security.AccessController.doPrivileged(
+ (PrivilegedAction<List<String>>) () -> {
+ List<String> ll;
+
+ // first try search keyword (max 6 domains)
+ ll = resolvconf("search", 6, 1);
+ if (ll.size() > 0) {
+ domain = ll.get(0);
+ return ll;
+ }
+
+ return null;
+
+ });
+ if (sl != null) {
+ return sl;
+ }
+
+ // No search keyword so use local domain
+
+
+ // LOCALDOMAIN has absolute priority on Solaris
+
+ String localDomain = localDomain0();
+ if (localDomain != null && !localDomain.isEmpty()) {
+ sl = new LinkedList<>();
+ sl.add(localDomain);
+ return Collections.unmodifiableList(sl);
+ }
+
+ // try domain keyword in /etc/resolv.conf
+
+ /* run */
+ sl = java.security.AccessController.doPrivileged(
+ (PrivilegedAction<List<String>>) () -> {
+ List<String> ll;
+
+ ll = resolvconf("domain", 1, 1);
+ if (ll.size() > 0) {
+ domain = ll.get(0);
+ return ll;
+ }
+ return null;
+
+ });
+ if (sl != null) {
+ // sl is already UnmodifiableList
+ return sl;
+ }
+
+ // no local domain so try fallback (RPC) domain or
+ // hostName
+
+ sl = new LinkedList<>();
+ String domain = fallbackDomain0();
+ if (domain != null && !domain.isEmpty()) {
+ sl.add(domain);
+ }
+
+ return Collections.unmodifiableList(sl);
+ }
+
+
+ // ----
+
+ public DnsResolverConfiguration() {
+ }
+
+ @SuppressWarnings("unchecked")
+ public List<String> searchlist() {
+ loadConfig();
+ // List is unmodifiable
+ return searchlist;
+ }
+
+ @SuppressWarnings("unchecked")
+ public List<String> nameservers() {
+ loadConfig();
+ // List is unmodifiable
+ return nameservers;
+ }
+
+ public String domain() {
+ loadConfig();
+ return domain;
+ }
+
+ // --- Native methods --
+
+ static native String localDomain0();
+
+ static native String fallbackDomain0();
+
+ static {
+ var pa = (PrivilegedAction<Void>) () -> {System.loadLibrary("resolver"); return null;};
+ if (System.getSecurityManager() == null) {
+ pa.run();
+ } else {
+ AccessController.doPrivileged(pa);
+ }
+ var pea = (PrivilegedExceptionAction<ReloadTracker>) () ->
+ ReloadTracker.newInstance(Paths.get(RESOLV_CONF_LOCATION), TIMEOUT);
+ // TODO: Revisit
+ try {
+ RESOLVE_CONF_TRACKER = System.getSecurityManager() == null ? pea.run()
+ : AccessController.doPrivileged(pea);
+ } catch (Exception e) {
+ throw new RuntimeException("Can't instantiate resolver configuration file tracker", e);
+ }
+ }
+
+}