1 /* 2 * Copyright (C) 2019 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.net.util; 18 19 import android.net.MacAddress; 20 import android.text.TextUtils; 21 22 import java.net.NetworkInterface; 23 import java.net.SocketException; 24 25 26 /** 27 * Encapsulate the interface parameters common to IpClient/IpServer components. 28 * 29 * Basically all java.net.NetworkInterface methods throw Exceptions. IpClient 30 * and IpServer (sub)components need most or all of this information at some 31 * point during their lifecycles, so pass only this simplified object around 32 * which can be created once when IpClient/IpServer are told to start. 33 * 34 * @hide 35 */ 36 public class InterfaceParams { 37 public final String name; 38 public final int index; 39 public final boolean hasMacAddress; 40 public final MacAddress macAddr; 41 public final int defaultMtu; 42 43 // TODO: move the below to NetworkStackConstants when this class is moved to the NetworkStack. 44 private static final int ETHER_MTU = 1500; 45 private static final int IPV6_MIN_MTU = 1280; 46 47 getByName(String name)48 public static InterfaceParams getByName(String name) { 49 final NetworkInterface netif = getNetworkInterfaceByName(name); 50 if (netif == null) return null; 51 52 // Not all interfaces have MAC addresses, e.g. rmnet_data0. 53 final MacAddress macAddr = getMacAddress(netif); 54 55 try { 56 return new InterfaceParams(name, netif.getIndex(), macAddr, netif.getMTU()); 57 } catch (IllegalArgumentException|SocketException e) { 58 return null; 59 } 60 } 61 InterfaceParams(String name, int index, MacAddress macAddr)62 public InterfaceParams(String name, int index, MacAddress macAddr) { 63 this(name, index, macAddr, ETHER_MTU); 64 } 65 InterfaceParams(String name, int index, MacAddress macAddr, int defaultMtu)66 public InterfaceParams(String name, int index, MacAddress macAddr, int defaultMtu) { 67 if (TextUtils.isEmpty(name)) { 68 throw new IllegalArgumentException("impossible interface name"); 69 } 70 71 if (index <= 0) throw new IllegalArgumentException("invalid interface index"); 72 73 this.name = name; 74 this.index = index; 75 this.hasMacAddress = (macAddr != null); 76 this.macAddr = hasMacAddress ? macAddr : MacAddress.fromBytes(new byte[] { 77 0x02, 0x00, 0x00, 0x00, 0x00, 0x00 }); 78 this.defaultMtu = (defaultMtu > IPV6_MIN_MTU) ? defaultMtu : IPV6_MIN_MTU; 79 } 80 81 @Override toString()82 public String toString() { 83 return String.format("%s/%d/%s/%d", name, index, macAddr, defaultMtu); 84 } 85 getNetworkInterfaceByName(String name)86 private static NetworkInterface getNetworkInterfaceByName(String name) { 87 try { 88 return NetworkInterface.getByName(name); 89 } catch (NullPointerException|SocketException e) { 90 return null; 91 } 92 } 93 getMacAddress(NetworkInterface netif)94 private static MacAddress getMacAddress(NetworkInterface netif) { 95 try { 96 return MacAddress.fromBytes(netif.getHardwareAddress()); 97 } catch (IllegalArgumentException|NullPointerException|SocketException e) { 98 return null; 99 } 100 } 101 } 102