| /* |
| * Copyright (c) 2011, 2013, 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 java.net; |
| |
| /** |
| * Choose a network interface to be the default for |
| * outgoing IPv6 traffic that does not specify a scope_id (and which needs one). |
| * We choose the first interface that is up and is (in order of preference): |
| * 1. neither loopback nor point to point |
| * 2. point to point |
| * 3. loopback |
| * 4. none. |
| * Platforms that do not require a default interface implement a dummy |
| * that returns null. |
| */ |
| |
| import java.util.Enumeration; |
| import java.io.IOException; |
| |
| class DefaultInterface { |
| |
| private final static NetworkInterface defaultInterface = |
| chooseDefaultInterface(); |
| |
| static NetworkInterface getDefault() { |
| return defaultInterface; |
| } |
| |
| /** |
| * Choose a default interface. This method returns an interface that is |
| * both "up" and supports multicast. This method choses an interface in |
| * order of preference: |
| * 1. neither loopback nor point to point |
| * 2. point to point |
| * 3. loopback |
| * |
| * @return the chosen interface or {@code null} if there isn't a suitable |
| * default |
| */ |
| private static NetworkInterface chooseDefaultInterface() { |
| Enumeration<NetworkInterface> nifs; |
| |
| try { |
| nifs = NetworkInterface.getNetworkInterfaces(); |
| } catch (IOException ignore) { |
| // unable to enumate network interfaces |
| return null; |
| } |
| |
| NetworkInterface ppp = null; |
| NetworkInterface loopback = null; |
| |
| while (nifs.hasMoreElements()) { |
| NetworkInterface ni = nifs.nextElement(); |
| try { |
| if (ni.isUp() && ni.supportsMulticast()) { |
| boolean isLoopback = ni.isLoopback(); |
| boolean isPPP = ni.isPointToPoint(); |
| if (!isLoopback && !isPPP) { |
| // found an interface that is not the loopback or a |
| // point-to-point interface |
| return ni; |
| } |
| if (ppp == null && isPPP) |
| ppp = ni; |
| if (loopback == null && isLoopback) |
| loopback = ni; |
| } |
| } catch (IOException skip) { } |
| } |
| |
| return (ppp != null) ? ppp : loopback; |
| } |
| } |