content: /*
   * Copyright (C) 2017 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 android.net.util;
  
  import android.net.IpPrefix;
  import android.net.LinkAddress;
  import android.net.LinkProperties;
  
  import java.net.Inet4Address;
  import java.net.InetAddress;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.Set;
  
  
  /**
   * @hide
   */
  public class PrefixUtils {
      private static final IpPrefix[] MIN_NON_FORWARDABLE_PREFIXES = {
              pfx("127.0.0.0/8"),     // IPv4 loopback
              pfx("169.254.0.0/16"),  // IPv4 link-local, RFC3927#section-8
              pfx("::/3"),
              pfx("fe80::/64"),       // IPv6 link-local
              pfx("fc00::/7"),        // IPv6 ULA
              pfx("ff02::/8"),        // IPv6 link-local multicast
      };
  
      public static final IpPrefix DEFAULT_WIFI_P2P_PREFIX = pfx("192.168.49.0/24");
  
      public static Set<IpPrefix> getNonForwardablePrefixes() {
          final HashSet<IpPrefix> prefixes = new HashSet<>();
          addNonForwardablePrefixes(prefixes);
          return prefixes;
      }
  
      public static void addNonForwardablePrefixes(Set<IpPrefix> prefixes) {
          Collections.addAll(prefixes, MIN_NON_FORWARDABLE_PREFIXES);
      }
  
      public static Set<IpPrefix> localPrefixesFrom(LinkProperties lp) {
          final HashSet<IpPrefix> localPrefixes = new HashSet<>();
          if (lp == null) return localPrefixes;
  
          for (LinkAddress addr : lp.getAllLinkAddresses()) {
              if (addr.getAddress().isLinkLocalAddress()) continue;
              localPrefixes.add(asIpPrefix(addr));
          }
          // TODO: Add directly-connected routes as well (ones from which we did
          // not also form a LinkAddress)?
  
          return localPrefixes;
      }
  
      public static IpPrefix asIpPrefix(LinkAddress addr) {
          return new IpPrefix(addr.getAddress(), addr.getPrefixLength());
      }
  
      public static IpPrefix ipAddressAsPrefix(InetAddress ip) {
          final int bitLength = (ip instanceof Inet4Address)
                  ? NetworkConstants.IPV4_ADDR_BITS
                  : NetworkConstants.IPV6_ADDR_BITS;
          return new IpPrefix(ip, bitLength);
      }
  
      private static IpPrefix pfx(String prefixStr) {
          return new IpPrefix(prefixStr);
      }
  }
  