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      1 /*
      2  * Copyright (C) 2017 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.IpPrefix;
     20 import android.net.LinkAddress;
     21 import android.net.LinkProperties;
     22 
     23 import java.net.Inet4Address;
     24 import java.net.InetAddress;
     25 import java.util.Collections;
     26 import java.util.HashSet;
     27 import java.util.Set;
     28 
     29 
     30 /**
     31  * @hide
     32  */
     33 public class PrefixUtils {
     34     private static final IpPrefix[] MIN_NON_FORWARDABLE_PREFIXES = {
     35             pfx("127.0.0.0/8"),     // IPv4 loopback
     36             pfx("169.254.0.0/16"),  // IPv4 link-local, RFC3927#section-8
     37             pfx("::/3"),
     38             pfx("fe80::/64"),       // IPv6 link-local
     39             pfx("fc00::/7"),        // IPv6 ULA
     40             pfx("ff02::/8"),        // IPv6 link-local multicast
     41     };
     42 
     43     public static final IpPrefix DEFAULT_WIFI_P2P_PREFIX = pfx("192.168.49.0/24");
     44 
     45     public static Set<IpPrefix> getNonForwardablePrefixes() {
     46         final HashSet<IpPrefix> prefixes = new HashSet<>();
     47         addNonForwardablePrefixes(prefixes);
     48         return prefixes;
     49     }
     50 
     51     public static void addNonForwardablePrefixes(Set<IpPrefix> prefixes) {
     52         Collections.addAll(prefixes, MIN_NON_FORWARDABLE_PREFIXES);
     53     }
     54 
     55     public static Set<IpPrefix> localPrefixesFrom(LinkProperties lp) {
     56         final HashSet<IpPrefix> localPrefixes = new HashSet<>();
     57         if (lp == null) return localPrefixes;
     58 
     59         for (LinkAddress addr : lp.getAllLinkAddresses()) {
     60             if (addr.getAddress().isLinkLocalAddress()) continue;
     61             localPrefixes.add(asIpPrefix(addr));
     62         }
     63         // TODO: Add directly-connected routes as well (ones from which we did
     64         // not also form a LinkAddress)?
     65 
     66         return localPrefixes;
     67     }
     68 
     69     public static IpPrefix asIpPrefix(LinkAddress addr) {
     70         return new IpPrefix(addr.getAddress(), addr.getPrefixLength());
     71     }
     72 
     73     public static IpPrefix ipAddressAsPrefix(InetAddress ip) {
     74         final int bitLength = (ip instanceof Inet4Address)
     75                 ? NetworkConstants.IPV4_ADDR_BITS
     76                 : NetworkConstants.IPV6_ADDR_BITS;
     77         return new IpPrefix(ip, bitLength);
     78     }
     79 
     80     private static IpPrefix pfx(String prefixStr) {
     81         return new IpPrefix(prefixStr);
     82     }
     83 }
     84