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NetworkInterface.getByInetAddress() may return null on Android platform (#10056)

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Motivation:

NetworkInterface.getByInetAddress() may return null on Android. This is incorrect by the API but still happens. To help our users we should provide a workaround

Modifications:

Just return an empty Enumeration when null is returned.

Result:

Fixes https://github.com/netty/netty/issues/10045
This commit is contained in:
Norman Maurer 2020-02-25 09:34:38 +01:00 committed by GitHub
parent 914b433a8d
commit 880e1239c5
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1 changed files with 17 additions and 1 deletions
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18
common/src/main/java/io/netty/util/internal/SocketUtils.java
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@ -32,6 +32,7 @@ import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.Collections;
import java.util.Enumeration;
/**
@ -42,9 +43,16 @@ import java.util.Enumeration;
*/
public final class SocketUtils {
private static final Enumeration<Object> EMPTY = Collections.enumeration(Collections.emptyList());
private SocketUtils() {
}
@SuppressWarnings("unchecked")
private static <T> Enumeration<T> empty() {
return (Enumeration<T>) EMPTY;
}
public static void connect(final Socket socket, final SocketAddress remoteAddress, final int timeout)
throws IOException {
try {
@ -176,12 +184,20 @@ public final class SocketUtils {
}
public static Enumeration<InetAddress> addressesFromNetworkInterface(final NetworkInterface intf) {
return AccessController.doPrivileged(new PrivilegedAction<Enumeration<InetAddress>>() {
Enumeration<InetAddress> addresses =
AccessController.doPrivileged(new PrivilegedAction<Enumeration<InetAddress>>() {
@Override
public Enumeration<InetAddress> run() {
return intf.getInetAddresses();
}
});
// Android seems to sometimes return null even if this is not a valid return value by the api docs.
// Just return an empty Enumeration in this case.
// See https://github.com/netty/netty/issues/10045
if (addresses == null) {
return empty();
}
return addresses;
}
@SuppressJava6Requirement(reason = "Usage guarded by java version check")