| /* |
| * Copyright 2019 The Android Open Source Project |
| * |
| * Licensed 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 com.android.net.module.util; |
| |
| import android.annotation.NonNull; |
| import android.annotation.Nullable; |
| import android.net.RouteInfo; |
| |
| import java.net.Inet4Address; |
| import java.net.Inet6Address; |
| import java.net.InetAddress; |
| import java.net.UnknownHostException; |
| import java.util.Collection; |
| |
| /** |
| * Collection of network common utilities. |
| * @hide |
| */ |
| public final class NetUtils { |
| |
| /** |
| * Check if IP address type is consistent between two InetAddress. |
| * @return true if both are the same type. False otherwise. |
| */ |
| public static boolean addressTypeMatches(@NonNull InetAddress left, |
| @NonNull InetAddress right) { |
| return (((left instanceof Inet4Address) && (right instanceof Inet4Address)) |
| || ((left instanceof Inet6Address) && (right instanceof Inet6Address))); |
| } |
| |
| /** |
| * Find the route from a Collection of routes that best matches a given address. |
| * May return null if no routes are applicable. |
| * @param routes a Collection of RouteInfos to chose from |
| * @param dest the InetAddress your trying to get to |
| * @return the RouteInfo from the Collection that best fits the given address |
| */ |
| @Nullable |
| public static RouteInfo selectBestRoute(@Nullable Collection<RouteInfo> routes, |
| @Nullable InetAddress dest) { |
| if ((routes == null) || (dest == null)) return null; |
| |
| RouteInfo bestRoute = null; |
| // pick a longest prefix match under same address type |
| for (RouteInfo route : routes) { |
| if (addressTypeMatches(route.getDestination().getAddress(), dest)) { |
| if ((bestRoute != null) |
| && (bestRoute.getDestination().getPrefixLength() |
| >= route.getDestination().getPrefixLength())) { |
| continue; |
| } |
| if (route.matches(dest)) bestRoute = route; |
| } |
| } |
| return bestRoute; |
| } |
| |
| /** |
| * Get InetAddress masked with prefixLength. Will never return null. |
| * @param address the IP address to mask with |
| * @param prefixLength the prefixLength used to mask the IP |
| */ |
| public static InetAddress getNetworkPart(InetAddress address, int prefixLength) { |
| byte[] array = address.getAddress(); |
| maskRawAddress(array, prefixLength); |
| |
| InetAddress netPart = null; |
| try { |
| netPart = InetAddress.getByAddress(array); |
| } catch (UnknownHostException e) { |
| throw new RuntimeException("getNetworkPart error - " + e.toString()); |
| } |
| return netPart; |
| } |
| |
| /** |
| * Masks a raw IP address byte array with the specified prefix length. |
| */ |
| public static void maskRawAddress(byte[] array, int prefixLength) { |
| if (prefixLength < 0 || prefixLength > array.length * 8) { |
| throw new RuntimeException("IP address with " + array.length |
| + " bytes has invalid prefix length " + prefixLength); |
| } |
| |
| int offset = prefixLength / 8; |
| int remainder = prefixLength % 8; |
| byte mask = (byte) (0xFF << (8 - remainder)); |
| |
| if (offset < array.length) array[offset] = (byte) (array[offset] & mask); |
| |
| offset++; |
| |
| for (; offset < array.length; offset++) { |
| array[offset] = 0; |
| } |
| } |
| } |