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NoClassDefFoundError on Android platform when try to use DefaultDnsServerAddressStreamProvider. (#8656) 

Motivation:

Andoid does not contain javax.naming.* so we should not try to use it to prevent a NoClassDefFoundError on init.

Modifications:

Only try to use javax.naming.* to retrieve nameservers when not using Android.

Result:

Fixes https://github.com/netty/netty/issues/8654.
This commit is contained in:
Norman Maurer 2018-12-14 21:31:21 +01:00 committed by GitHub
parent 29d185b796
commit a3844da10b
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 82 additions and 42 deletions
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47
resolver-dns/src/main/java/io/netty/resolver/dns/DefaultDnsServerAddressStreamProvider.java
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@ -16,23 +16,17 @@
package io.netty.resolver.dns;
import io.netty.util.NetUtil;
import io.netty.util.internal.PlatformDependent;
import io.netty.util.internal.SocketUtils;
import io.netty.util.internal.UnstableApi;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;
import javax.naming.Context;
import javax.naming.NamingException;
import javax.naming.directory.DirContext;
import javax.naming.directory.InitialDirContext;
import java.lang.reflect.Method;
import java.net.Inet6Address;
import java.net.InetSocketAddress;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Hashtable;
import java.util.List;
import static io.netty.resolver.dns.DnsServerAddresses.sequential;
@ -55,41 +49,10 @@ public final class DefaultDnsServerAddressStreamProvider implements DnsServerAdd
static {
final List<InetSocketAddress> defaultNameServers = new ArrayList<InetSocketAddress>(2);
// Using jndi-dns to obtain the default name servers.
//
// See:
// - http://docs.oracle.com/javase/8/docs/technotes/guides/jndi/jndi-dns.html
// - http://mail.openjdk.java.net/pipermail/net-dev/2017-March/010695.html
Hashtable<String, String> env = new Hashtable<String, String>();
env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.dns.DnsContextFactory");
env.put("java.naming.provider.url", "dns://");
try {
DirContext ctx = new InitialDirContext(env);
String dnsUrls = (String) ctx.getEnvironment().get("java.naming.provider.url");
// Only try if not empty as otherwise we will produce an exception
if (dnsUrls != null && !dnsUrls.isEmpty()) {
String[] servers = dnsUrls.split(" ");
for (String server : servers) {
try {
URI uri = new URI(server);
String host = new URI(server).getHost();
if (host == null || host.isEmpty()) {
logger.debug(
"Skipping a nameserver URI as host portion could not be extracted: {}", server);
// If the host portion can not be parsed we should just skip this entry.
continue;
}
int port = uri.getPort();
defaultNameServers.add(SocketUtils.socketAddress(uri.getHost(), port == -1 ? DNS_PORT : port));
} catch (URISyntaxException e) {
logger.debug("Skipping a malformed nameserver URI: {}", server, e);
}
}
}
} catch (NamingException ignore) {
// Will try reflection if this fails.
if (!PlatformDependent.isAndroid()) {
// Only try to use when not on Android as the classes not exists there:
// See https://github.com/netty/netty/issues/8654
DirContextUtils.addNameServers(defaultNameServers, DNS_PORT);
}
if (defaultNameServers.isEmpty()) {

77
resolver-dns/src/main/java/io/netty/resolver/dns/DirContextUtils.java Normal file
View File

@ -0,0 +1,77 @@
/*
* Copyright 2018 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.resolver.dns;
import io.netty.util.internal.SocketUtils;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;
import javax.naming.Context;
import javax.naming.NamingException;
import javax.naming.directory.DirContext;
import javax.naming.directory.InitialDirContext;
import java.net.InetSocketAddress;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Hashtable;
import java.util.List;
final class DirContextUtils {
private static final InternalLogger logger =
InternalLoggerFactory.getInstance(DirContextUtils.class);
private DirContextUtils() { }
static void addNameServers(List<InetSocketAddress> defaultNameServers, int defaultPort) {
// Using jndi-dns to obtain the default name servers.
//
// See:
// - http://docs.oracle.com/javase/8/docs/technotes/guides/jndi/jndi-dns.html
// - http://mail.openjdk.java.net/pipermail/net-dev/2017-March/010695.html
Hashtable<String, String> env = new Hashtable<String, String>();
env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.dns.DnsContextFactory");
env.put("java.naming.provider.url", "dns://");
try {
DirContext ctx = new InitialDirContext(env);
String dnsUrls = (String) ctx.getEnvironment().get("java.naming.provider.url");
// Only try if not empty as otherwise we will produce an exception
if (dnsUrls != null && !dnsUrls.isEmpty()) {
String[] servers = dnsUrls.split(" ");
for (String server : servers) {
try {
URI uri = new URI(server);
String host = new URI(server).getHost();
if (host == null || host.isEmpty()) {
logger.debug(
"Skipping a nameserver URI as host portion could not be extracted: {}", server);
// If the host portion can not be parsed we should just skip this entry.
continue;
}
int port = uri.getPort();
defaultNameServers.add(SocketUtils.socketAddress(uri.getHost(), port == -1 ?
defaultPort : port));
} catch (URISyntaxException e) {
logger.debug("Skipping a malformed nameserver URI: {}", server, e);
}
}
}
} catch (NamingException ignore) {
// Will try reflection if this fails.
}
}
}