android-35/android/net/RouteInfo.java - platform/prebuilts/fullsdk/sources - Git at Google

 /*
  * Copyright (C) 2011 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;

 import android.annotation.IntDef;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.annotation.SystemApi;
 import android.compat.annotation.UnsupportedAppUsage;
 import android.os.Build;
 import android.os.Parcel;
 import android.os.Parcelable;

 import com.android.net.module.util.NetUtils;
 import com.android.net.module.util.NetworkStackConstants;

 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.net.Inet4Address;
 import java.net.Inet6Address;
 import java.net.InetAddress;
 import java.net.UnknownHostException;
 import java.util.Collection;
 import java.util.Objects;

 /**
  * Represents a network route.
  * <p>
  * This is used both to describe static network configuration and live network
  * configuration information.
  *
  * A route contains three pieces of information:
  * <ul>
  * <li>a destination {@link IpPrefix} specifying the network destinations covered by this route.
  *     If this is {@code null} it indicates a default route of the address family (IPv4 or IPv6)
  *     implied by the gateway IP address.
  * <li>a gateway {@link InetAddress} indicating the next hop to use.  If this is {@code null} it
  *     indicates a directly-connected route.
  * <li>an interface (which may be unspecified).
  * </ul>
  * Either the destination or the gateway may be {@code null}, but not both.  If the
  * destination and gateway are both specified, they must be of the same address family
  * (IPv4 or IPv6).
  */
 public final class RouteInfo implements Parcelable {
     /** @hide */
     @IntDef(value = {
             RTN_UNICAST,
             RTN_UNREACHABLE,
             RTN_THROW,
     })
     @Retention(RetentionPolicy.SOURCE)
     public @interface RouteType {}

     /**
      * The IP destination address for this route.
      */
     @NonNull
     private final IpPrefix mDestination;

     /**
      * The gateway address for this route.
      */
     @UnsupportedAppUsage
     @Nullable
     private final InetAddress mGateway;

     /**
      * The interface for this route.
      */
     @Nullable
     private final String mInterface;


     /**
      * Unicast route.
      *
      * Indicates that destination is reachable directly or via gateway.
      **/
     public static final int RTN_UNICAST = 1;

     /**
      * Unreachable route.
      *
      * Indicates that destination is unreachable.
      **/
     public static final int RTN_UNREACHABLE = 7;

     /**
      * Throw route.
      *
      * Indicates that routing information about this destination is not in this table.
      * Routing lookup should continue in another table.
      **/
     public static final int RTN_THROW = 9;

     /**
      * The type of this route; one of the RTN_xxx constants above.
      */
     private final int mType;

     /**
      * The maximum transmission unit size for this route.
      */
     private final int mMtu;

     // Derived data members.
     // TODO: remove these.
     @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023)
     private final boolean mIsHost;
     private final boolean mHasGateway;

     /**
      * Constructs a RouteInfo object.
      *
      * If destination is null, then gateway must be specified and the
      * constructed route is either the IPv4 default route <code>0.0.0.0</code>
      * if the gateway is an instance of {@link Inet4Address}, or the IPv6 default
      * route <code>::/0</code> if gateway is an instance of
      * {@link Inet6Address}.
      * <p>
      * destination and gateway may not both be null.
      *
      * @param destination the destination prefix
      * @param gateway the IP address to route packets through
      * @param iface the interface name to send packets on
      * @param type the type of this route
      *
      * @hide
      */
     @SystemApi
     public RouteInfo(@Nullable IpPrefix destination, @Nullable InetAddress gateway,
             @Nullable String iface, @RouteType int type) {
         this(destination, gateway, iface, type, 0);
     }

     /**
      * Constructs a RouteInfo object.
      *
      * If destination is null, then gateway must be specified and the
      * constructed route is either the IPv4 default route <code>0.0.0.0</code>
      * if the gateway is an instance of {@link Inet4Address}, or the IPv6 default
      * route <code>::/0</code> if gateway is an instance of
      * {@link Inet6Address}.
      * <p>
      * destination and gateway may not both be null.
      *
      * @param destination the destination prefix
      * @param gateway the IP address to route packets through
      * @param iface the interface name to send packets on
      * @param type the type of this route
      * @param mtu the maximum transmission unit size for this route
      *
      * @hide
      */
     @SystemApi
     public RouteInfo(@Nullable IpPrefix destination, @Nullable InetAddress gateway,
             @Nullable String iface, @RouteType int type, int mtu) {
         switch (type) {
             case RTN_UNICAST:
             case RTN_UNREACHABLE:
             case RTN_THROW:
                 // TODO: It would be nice to ensure that route types that don't have nexthops or
                 // interfaces, such as unreachable or throw, can't be created if an interface or
                 // a gateway is specified. This is a bit too complicated to do at the moment
                 // because:
                 //
                 // - LinkProperties sets the interface on routes added to it, and modifies the
                 //   interfaces of all the routes when its interface name changes.
                 // - Even when the gateway is null, we store a non-null gateway here.
                 //
                 // For now, we just rely on the code that sets routes to do things properly.
                 break;
             default:
                 throw new IllegalArgumentException("Unknown route type " + type);
         }

         if (destination == null) {
             if (gateway != null) {
                 if (gateway instanceof Inet4Address) {
                     destination = new IpPrefix(NetworkStackConstants.IPV4_ADDR_ANY, 0);
                 } else {
                     destination = new IpPrefix(NetworkStackConstants.IPV6_ADDR_ANY, 0);
                 }
             } else {
                 // no destination, no gateway. invalid.
                 throw new IllegalArgumentException("Invalid arguments passed in: " + gateway + "," +
                         destination);
             }
         }
         // TODO: set mGateway to null if there is no gateway. This is more correct, saves space, and
         // matches the documented behaviour. Before we can do this we need to fix all callers (e.g.,
         // ConnectivityService) to stop doing things like r.getGateway().equals(), ... .
         if (gateway == null) {
             if (destination.getAddress() instanceof Inet4Address) {
                 gateway = NetworkStackConstants.IPV4_ADDR_ANY;
             } else {
                 gateway = NetworkStackConstants.IPV6_ADDR_ANY;
             }
         }
         mHasGateway = (!gateway.isAnyLocalAddress());

         if ((destination.getAddress() instanceof Inet4Address
                 && !(gateway instanceof Inet4Address))
                 || (destination.getAddress() instanceof Inet6Address
                 && !(gateway instanceof Inet6Address))) {
             throw new IllegalArgumentException("address family mismatch in RouteInfo constructor");
         }
         mDestination = destination;  // IpPrefix objects are immutable.
         mGateway = gateway;          // InetAddress objects are immutable.
         mInterface = iface;          // Strings are immutable.
         mType = type;
         mIsHost = isHost();
         mMtu = mtu;
     }

     /**
      * Constructs a {@code RouteInfo} object.
      *
      * If destination is null, then gateway must be specified and the
      * constructed route is either the IPv4 default route <code>0.0.0.0</code>
      * if the gateway is an instance of {@link Inet4Address}, or the IPv6 default
      * route <code>::/0</code> if gateway is an instance of {@link Inet6Address}.
      * <p>
      * Destination and gateway may not both be null.
      *
      * @param destination the destination address and prefix in an {@link IpPrefix}
      * @param gateway the {@link InetAddress} to route packets through
      * @param iface the interface name to send packets on
      *
      * @hide
      */
     @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
     public RouteInfo(@Nullable IpPrefix destination, @Nullable InetAddress gateway,
             @Nullable String iface) {
         this(destination, gateway, iface, RTN_UNICAST);
     }

     /**
      * @hide
      */
     @UnsupportedAppUsage
     public RouteInfo(@Nullable LinkAddress destination, @Nullable InetAddress gateway,
             @Nullable String iface) {
         this(destination == null ? null :
                 new IpPrefix(destination.getAddress(), destination.getPrefixLength()),
                 gateway, iface);
     }

     /**
      * Constructs a {@code RouteInfo} object.
      *
      * If destination is null, then gateway must be specified and the
      * constructed route is either the IPv4 default route <code>0.0.0.0</code>
      * if the gateway is an instance of {@link Inet4Address}, or the IPv6 default
      * route <code>::/0</code> if gateway is an instance of {@link Inet6Address}.
      * <p>
      * Destination and gateway may not both be null.
      *
      * @param destination the destination address and prefix in an {@link IpPrefix}
      * @param gateway the {@link InetAddress} to route packets through
      *
      * @hide
      */
     public RouteInfo(@Nullable IpPrefix destination, @Nullable InetAddress gateway) {
         this(destination, gateway, null);
     }

     /**
      * @hide
      *
      * TODO: Remove this.
      */
     @UnsupportedAppUsage
     public RouteInfo(@Nullable LinkAddress destination, @Nullable InetAddress gateway) {
         this(destination, gateway, null);
     }

     /**
      * Constructs a default {@code RouteInfo} object.
      *
      * @param gateway the {@link InetAddress} to route packets through
      *
      * @hide
      */
     @UnsupportedAppUsage
     public RouteInfo(@NonNull InetAddress gateway) {
         this((IpPrefix) null, gateway, null);
     }

     /**
      * Constructs a {@code RouteInfo} object representing a direct connected subnet.
      *
      * @param destination the {@link IpPrefix} describing the address and prefix
      *                    length of the subnet.
      *
      * @hide
      */
     public RouteInfo(@NonNull IpPrefix destination) {
         this(destination, null, null);
     }

     /**
      * @hide
      */
     public RouteInfo(@NonNull LinkAddress destination) {
         this(destination, null, null);
     }

     /**
      * @hide
      */
     public RouteInfo(@NonNull IpPrefix destination, @RouteType int type) {
         this(destination, null, null, type);
     }

     /**
      * @hide
      */
     public static RouteInfo makeHostRoute(@NonNull InetAddress host, @Nullable String iface) {
         return makeHostRoute(host, null, iface);
     }

     /**
      * @hide
      */
     public static RouteInfo makeHostRoute(@Nullable InetAddress host, @Nullable InetAddress gateway,
             @Nullable String iface) {
         if (host == null) return null;

         if (host instanceof Inet4Address) {
             return new RouteInfo(new IpPrefix(host, 32), gateway, iface);
         } else {
             return new RouteInfo(new IpPrefix(host, 128), gateway, iface);
         }
     }

     @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023)
     private boolean isHost() {
         return (mDestination.getAddress() instanceof Inet4Address &&
                 mDestination.getPrefixLength() == 32) ||
                (mDestination.getAddress() instanceof Inet6Address &&
                 mDestination.getPrefixLength() == 128);
     }

     /**
      * Retrieves the destination address and prefix length in the form of an {@link IpPrefix}.
      *
      * @return {@link IpPrefix} specifying the destination.  This is never {@code null}.
      */
     @NonNull
     public IpPrefix getDestination() {
         return mDestination;
     }

     /**
      * TODO: Convert callers to use IpPrefix and then remove.
      * @hide
      */
     @NonNull
     public LinkAddress getDestinationLinkAddress() {
         return new LinkAddress(mDestination.getAddress(), mDestination.getPrefixLength());
     }

     /**
      * Retrieves the gateway or next hop {@link InetAddress} for this route.
      *
      * @return {@link InetAddress} specifying the gateway or next hop.  This may be
      *                             {@code null} for a directly-connected route."
      */
     @Nullable
     public InetAddress getGateway() {
         return mGateway;
     }

     /**
      * Retrieves the interface used for this route if specified, else {@code null}.
      *
      * @return The name of the interface used for this route.
      */
     @Nullable
     public String getInterface() {
         return mInterface;
     }

     /**
      * Retrieves the type of this route.
      *
      * @return The type of this route; one of the {@code RTN_xxx} constants defined in this class.
      */
     @RouteType
     public int getType() {
         return mType;
     }

     /**
      * Retrieves the MTU size for this route.
      *
      * @return The MTU size, or 0 if it has not been set.
      * @hide
      */
     @SystemApi
     public int getMtu() {
         return mMtu;
     }

     /**
      * Indicates if this route is a default route (ie, has no destination specified).
      *
      * @return {@code true} if the destination has a prefix length of 0.
      */
     public boolean isDefaultRoute() {
         return mType == RTN_UNICAST && mDestination.getPrefixLength() == 0;
     }

     /**
      * Indicates if this route is an unreachable default route.
      *
      * @return {@code true} if it's an unreachable route with prefix length of 0.
      * @hide
      */
     private boolean isUnreachableDefaultRoute() {
         return mType == RTN_UNREACHABLE && mDestination.getPrefixLength() == 0;
     }

     /**
      * Indicates if this route is an IPv4 default route.
      * @hide
      */
     public boolean isIPv4Default() {
         return isDefaultRoute() && mDestination.getAddress() instanceof Inet4Address;
     }

     /**
      * Indicates if this route is an IPv4 unreachable default route.
      * @hide
      */
     public boolean isIPv4UnreachableDefault() {
         return isUnreachableDefaultRoute() && mDestination.getAddress() instanceof Inet4Address;
     }

     /**
      * Indicates if this route is an IPv6 default route.
      * @hide
      */
     public boolean isIPv6Default() {
         return isDefaultRoute() && mDestination.getAddress() instanceof Inet6Address;
     }

     /**
      * Indicates if this route is an IPv6 unreachable default route.
      * @hide
      */
     public boolean isIPv6UnreachableDefault() {
         return isUnreachableDefaultRoute() && mDestination.getAddress() instanceof Inet6Address;
     }

     /**
      * Indicates if this route is a host route (ie, matches only a single host address).
      *
      * @return {@code true} if the destination has a prefix length of 32 or 128 for IPv4 or IPv6,
      * respectively.
      * @hide
      */
     public boolean isHostRoute() {
         return mIsHost;
     }

     /**
      * Indicates if this route has a next hop ({@code true}) or is directly-connected
      * ({@code false}).
      *
      * @return {@code true} if a gateway is specified
      */
     public boolean hasGateway() {
         return mHasGateway;
     }

     /**
      * Determines whether the destination and prefix of this route includes the specified
      * address.
      *
      * @param destination A {@link InetAddress} to test to see if it would match this route.
      * @return {@code true} if the destination and prefix length cover the given address.
      */
     public boolean matches(InetAddress destination) {
         return mDestination.contains(destination);
     }

     /**
      * 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
      *
      * @hide
      */
     @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
     @Nullable
     public static RouteInfo selectBestRoute(Collection<RouteInfo> routes, InetAddress dest) {
         return NetUtils.selectBestRoute(routes, dest);
     }

     /**
      * Returns a human-readable description of this object.
      */
     public String toString() {
         String val = "";
         if (mDestination != null) val = mDestination.toString();
         if (mType == RTN_UNREACHABLE) {
             val += " unreachable";
         } else if (mType == RTN_THROW) {
             val += " throw";
         } else {
             val += " ->";
             if (mGateway != null) val += " " + mGateway.getHostAddress();
             if (mInterface != null) val += " " + mInterface;
             if (mType != RTN_UNICAST) {
                 val += " unknown type " + mType;
             }
         }
         val += " mtu " + mMtu;
         return val;
     }

     /**
      * Compares this RouteInfo object against the specified object and indicates if they are equal.
      * @return {@code true} if the objects are equal, {@code false} otherwise.
      */
     public boolean equals(@Nullable Object obj) {
         if (this == obj) return true;

         if (!(obj instanceof RouteInfo)) return false;

         RouteInfo target = (RouteInfo) obj;

         return Objects.equals(mDestination, target.getDestination()) &&
                 Objects.equals(mGateway, target.getGateway()) &&
                 Objects.equals(mInterface, target.getInterface()) &&
                 mType == target.getType() && mMtu == target.getMtu();
     }

     /**
      * A helper class that contains the destination, the gateway and the interface in a
      * {@code RouteInfo}, used by {@link ConnectivityService#updateRoutes} or
      * {@link LinkProperties#addRoute} to calculate the list to be updated.
      * {@code RouteInfo} objects with different interfaces are treated as different routes because
      * *usually* on Android different interfaces use different routing tables, and moving a route
      * to a new routing table never constitutes an update, but is always a remove and an add.
      *
      * @hide
      */
     public static class RouteKey {
         @NonNull private final IpPrefix mDestination;
         @Nullable private final InetAddress mGateway;
         @Nullable private final String mInterface;

         RouteKey(@NonNull IpPrefix destination, @Nullable InetAddress gateway,
                 @Nullable String iface) {
             mDestination = destination;
             mGateway = gateway;
             mInterface = iface;
         }

         @Override
         public boolean equals(@Nullable Object o) {
             if (!(o instanceof RouteKey)) {
                 return false;
             }
             RouteKey p = (RouteKey) o;
             // No need to do anything special for scoped addresses. Inet6Address#equals does not
             // consider the scope ID, but the route IPCs (e.g., RoutingCoordinatorManager#addRoute)
             // and the kernel ignore scoped addresses both in the prefix and in the nexthop and only
             // look at RTA_OIF.
             return Objects.equals(p.mDestination, mDestination)
                     && Objects.equals(p.mGateway, mGateway)
                     && Objects.equals(p.mInterface, mInterface);
         }

         @Override
         public int hashCode() {
             return Objects.hash(mDestination, mGateway, mInterface);
         }
     }

     /**
      * Get {@code RouteKey} of this {@code RouteInfo}.
      * @return a {@code RouteKey} object.
      *
      * @hide
      */
     @NonNull
     public RouteKey getRouteKey() {
         return new RouteKey(mDestination, mGateway, mInterface);
     }

     /**
      *  Returns a hashcode for this <code>RouteInfo</code> object.
      */
     public int hashCode() {
         return (mDestination.hashCode() * 41)
                 + (mGateway == null ? 0 :mGateway.hashCode() * 47)
                 + (mInterface == null ? 0 :mInterface.hashCode() * 67)
                 + (mType * 71) + (mMtu * 89);
     }

     /**
      * Implement the Parcelable interface
      */
     public int describeContents() {
         return 0;
     }

     /**
      * Implement the Parcelable interface
      */
     public void writeToParcel(Parcel dest, int flags) {
         dest.writeParcelable(mDestination, flags);
         byte[] gatewayBytes = (mGateway == null) ? null : mGateway.getAddress();
         dest.writeByteArray(gatewayBytes);
         dest.writeString(mInterface);
         dest.writeInt(mType);
         dest.writeInt(mMtu);
     }

     /**
      * Implement the Parcelable interface.
      */
     public static final @android.annotation.NonNull Creator<RouteInfo> CREATOR =
         new Creator<RouteInfo>() {
         public RouteInfo createFromParcel(Parcel in) {
             IpPrefix dest = in.readParcelable(null);

             InetAddress gateway = null;
             byte[] addr = in.createByteArray();
             try {
                 gateway = InetAddress.getByAddress(addr);
             } catch (UnknownHostException e) {}

             String iface = in.readString();
             int type = in.readInt();
             int mtu = in.readInt();

             return new RouteInfo(dest, gateway, iface, type, mtu);
         }

         public RouteInfo[] newArray(int size) {
             return new RouteInfo[size];
         }
     };
 }
	/*
	* Copyright (C) 2011 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;

	import android.annotation.IntDef;
	import android.annotation.NonNull;
	import android.annotation.Nullable;
	import android.annotation.SystemApi;
	import android.compat.annotation.UnsupportedAppUsage;
	import android.os.Build;
	import android.os.Parcel;
	import android.os.Parcelable;

	import com.android.net.module.util.NetUtils;
	import com.android.net.module.util.NetworkStackConstants;

	import java.lang.annotation.Retention;
	import java.lang.annotation.RetentionPolicy;
	import java.net.Inet4Address;
	import java.net.Inet6Address;
	import java.net.InetAddress;
	import java.net.UnknownHostException;
	import java.util.Collection;
	import java.util.Objects;

	/**
	* Represents a network route.
	* <p>
	* This is used both to describe static network configuration and live network
	* configuration information.
	*
	* A route contains three pieces of information:
	* <ul>
	* <li>a destination {@link IpPrefix} specifying the network destinations covered by this route.
	* If this is {@code null} it indicates a default route of the address family (IPv4 or IPv6)
	* implied by the gateway IP address.
	* <li>a gateway {@link InetAddress} indicating the next hop to use. If this is {@code null} it
	* indicates a directly-connected route.
	* <li>an interface (which may be unspecified).
	* </ul>
	* Either the destination or the gateway may be {@code null}, but not both. If the
	* destination and gateway are both specified, they must be of the same address family
	* (IPv4 or IPv6).
	*/
	public final class RouteInfo implements Parcelable {
	/** @hide */
	@IntDef(value = {
	RTN_UNICAST,
	RTN_UNREACHABLE,
	RTN_THROW,
	})
	@Retention(RetentionPolicy.SOURCE)
	public @interface RouteType {}

	/**
	* The IP destination address for this route.
	*/
	@NonNull
	private final IpPrefix mDestination;

	/**
	* The gateway address for this route.
	*/
	@UnsupportedAppUsage
	@Nullable
	private final InetAddress mGateway;

	/**
	* The interface for this route.
	*/
	@Nullable
	private final String mInterface;


	/**
	* Unicast route.
	*
	* Indicates that destination is reachable directly or via gateway.
	**/
	public static final int RTN_UNICAST = 1;

	/**
	* Unreachable route.
	*
	* Indicates that destination is unreachable.
	**/
	public static final int RTN_UNREACHABLE = 7;

	/**
	* Throw route.
	*
	* Indicates that routing information about this destination is not in this table.
	* Routing lookup should continue in another table.
	**/
	public static final int RTN_THROW = 9;

	/**
	* The type of this route; one of the RTN_xxx constants above.
	*/
	private final int mType;

	/**
	* The maximum transmission unit size for this route.
	*/
	private final int mMtu;

	// Derived data members.
	// TODO: remove these.
	@UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023)
	private final boolean mIsHost;
	private final boolean mHasGateway;

	/**
	* Constructs a RouteInfo object.
	*
	* If destination is null, then gateway must be specified and the
	* constructed route is either the IPv4 default route <code>0.0.0.0</code>
	* if the gateway is an instance of {@link Inet4Address}, or the IPv6 default
	* route <code>::/0</code> if gateway is an instance of
	* {@link Inet6Address}.
	* <p>
	* destination and gateway may not both be null.
	*
	* @param destination the destination prefix
	* @param gateway the IP address to route packets through
	* @param iface the interface name to send packets on
	* @param type the type of this route
	*
	* @hide
	*/
	@SystemApi
	public RouteInfo(@Nullable IpPrefix destination, @Nullable InetAddress gateway,
	@Nullable String iface, @RouteType int type) {
	this(destination, gateway, iface, type, 0);
	}

	/**
	* Constructs a RouteInfo object.
	*
	* If destination is null, then gateway must be specified and the
	* constructed route is either the IPv4 default route <code>0.0.0.0</code>
	* if the gateway is an instance of {@link Inet4Address}, or the IPv6 default
	* route <code>::/0</code> if gateway is an instance of
	* {@link Inet6Address}.
	* <p>
	* destination and gateway may not both be null.
	*
	* @param destination the destination prefix
	* @param gateway the IP address to route packets through
	* @param iface the interface name to send packets on
	* @param type the type of this route
	* @param mtu the maximum transmission unit size for this route
	*
	* @hide
	*/
	@SystemApi
	public RouteInfo(@Nullable IpPrefix destination, @Nullable InetAddress gateway,
	@Nullable String iface, @RouteType int type, int mtu) {
	switch (type) {
	case RTN_UNICAST:
	case RTN_UNREACHABLE:
	case RTN_THROW:
	// TODO: It would be nice to ensure that route types that don't have nexthops or
	// interfaces, such as unreachable or throw, can't be created if an interface or
	// a gateway is specified. This is a bit too complicated to do at the moment
	// because:
	//
	// - LinkProperties sets the interface on routes added to it, and modifies the
	// interfaces of all the routes when its interface name changes.
	// - Even when the gateway is null, we store a non-null gateway here.
	//
	// For now, we just rely on the code that sets routes to do things properly.
	break;
	default:
	throw new IllegalArgumentException("Unknown route type " + type);
	}

	if (destination == null) {
	if (gateway != null) {
	if (gateway instanceof Inet4Address) {
	destination = new IpPrefix(NetworkStackConstants.IPV4_ADDR_ANY, 0);
	} else {
	destination = new IpPrefix(NetworkStackConstants.IPV6_ADDR_ANY, 0);
	}
	} else {
	// no destination, no gateway. invalid.
	throw new IllegalArgumentException("Invalid arguments passed in: " + gateway + "," +
	destination);
	}
	}
	// TODO: set mGateway to null if there is no gateway. This is more correct, saves space, and
	// matches the documented behaviour. Before we can do this we need to fix all callers (e.g.,
	// ConnectivityService) to stop doing things like r.getGateway().equals(), ... .
	if (gateway == null) {
	if (destination.getAddress() instanceof Inet4Address) {
	gateway = NetworkStackConstants.IPV4_ADDR_ANY;
	} else {
	gateway = NetworkStackConstants.IPV6_ADDR_ANY;
	}
	}
	mHasGateway = (!gateway.isAnyLocalAddress());

	if ((destination.getAddress() instanceof Inet4Address
	&& !(gateway instanceof Inet4Address))
	\|\| (destination.getAddress() instanceof Inet6Address
	&& !(gateway instanceof Inet6Address))) {
	throw new IllegalArgumentException("address family mismatch in RouteInfo constructor");
	}
	mDestination = destination; // IpPrefix objects are immutable.
	mGateway = gateway; // InetAddress objects are immutable.
	mInterface = iface; // Strings are immutable.
	mType = type;
	mIsHost = isHost();
	mMtu = mtu;
	}

	/**
	* Constructs a {@code RouteInfo} object.
	*
	* If destination is null, then gateway must be specified and the
	* constructed route is either the IPv4 default route <code>0.0.0.0</code>
	* if the gateway is an instance of {@link Inet4Address}, or the IPv6 default
	* route <code>::/0</code> if gateway is an instance of {@link Inet6Address}.
	* <p>
	* Destination and gateway may not both be null.
	*
	* @param destination the destination address and prefix in an {@link IpPrefix}
	* @param gateway the {@link InetAddress} to route packets through
	* @param iface the interface name to send packets on
	*
	* @hide
	*/
	@UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
	public RouteInfo(@Nullable IpPrefix destination, @Nullable InetAddress gateway,
	@Nullable String iface) {
	this(destination, gateway, iface, RTN_UNICAST);
	}

	/**
	* @hide
	*/
	@UnsupportedAppUsage
	public RouteInfo(@Nullable LinkAddress destination, @Nullable InetAddress gateway,
	@Nullable String iface) {
	this(destination == null ? null :
	new IpPrefix(destination.getAddress(), destination.getPrefixLength()),
	gateway, iface);
	}

	/**
	* Constructs a {@code RouteInfo} object.
	*
	* If destination is null, then gateway must be specified and the
	* constructed route is either the IPv4 default route <code>0.0.0.0</code>
	* if the gateway is an instance of {@link Inet4Address}, or the IPv6 default
	* route <code>::/0</code> if gateway is an instance of {@link Inet6Address}.
	* <p>
	* Destination and gateway may not both be null.
	*
	* @param destination the destination address and prefix in an {@link IpPrefix}
	* @param gateway the {@link InetAddress} to route packets through
	*
	* @hide
	*/
	public RouteInfo(@Nullable IpPrefix destination, @Nullable InetAddress gateway) {
	this(destination, gateway, null);
	}

	/**
	* @hide
	*
	* TODO: Remove this.
	*/
	@UnsupportedAppUsage
	public RouteInfo(@Nullable LinkAddress destination, @Nullable InetAddress gateway) {
	this(destination, gateway, null);
	}

	/**
	* Constructs a default {@code RouteInfo} object.
	*
	* @param gateway the {@link InetAddress} to route packets through
	*
	* @hide
	*/
	@UnsupportedAppUsage
	public RouteInfo(@NonNull InetAddress gateway) {
	this((IpPrefix) null, gateway, null);
	}

	/**
	* Constructs a {@code RouteInfo} object representing a direct connected subnet.
	*
	* @param destination the {@link IpPrefix} describing the address and prefix
	* length of the subnet.
	*
	* @hide
	*/
	public RouteInfo(@NonNull IpPrefix destination) {
	this(destination, null, null);
	}

	/**
	* @hide
	*/
	public RouteInfo(@NonNull LinkAddress destination) {
	this(destination, null, null);
	}

	/**
	* @hide
	*/
	public RouteInfo(@NonNull IpPrefix destination, @RouteType int type) {
	this(destination, null, null, type);
	}

	/**
	* @hide
	*/
	public static RouteInfo makeHostRoute(@NonNull InetAddress host, @Nullable String iface) {
	return makeHostRoute(host, null, iface);
	}

	/**
	* @hide
	*/
	public static RouteInfo makeHostRoute(@Nullable InetAddress host, @Nullable InetAddress gateway,
	@Nullable String iface) {
	if (host == null) return null;

	if (host instanceof Inet4Address) {
	return new RouteInfo(new IpPrefix(host, 32), gateway, iface);
	} else {
	return new RouteInfo(new IpPrefix(host, 128), gateway, iface);
	}
	}

	@UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023)
	private boolean isHost() {
	return (mDestination.getAddress() instanceof Inet4Address &&
	mDestination.getPrefixLength() == 32) \|\|
	(mDestination.getAddress() instanceof Inet6Address &&
	mDestination.getPrefixLength() == 128);
	}

	/**
	* Retrieves the destination address and prefix length in the form of an {@link IpPrefix}.
	*
	* @return {@link IpPrefix} specifying the destination. This is never {@code null}.
	*/
	@NonNull
	public IpPrefix getDestination() {
	return mDestination;
	}

	/**
	* TODO: Convert callers to use IpPrefix and then remove.
	* @hide
	*/
	@NonNull
	public LinkAddress getDestinationLinkAddress() {
	return new LinkAddress(mDestination.getAddress(), mDestination.getPrefixLength());
	}

	/**
	* Retrieves the gateway or next hop {@link InetAddress} for this route.
	*
	* @return {@link InetAddress} specifying the gateway or next hop. This may be
	* {@code null} for a directly-connected route."
	*/
	@Nullable
	public InetAddress getGateway() {
	return mGateway;
	}

	/**
	* Retrieves the interface used for this route if specified, else {@code null}.
	*
	* @return The name of the interface used for this route.
	*/
	@Nullable
	public String getInterface() {
	return mInterface;
	}

	/**
	* Retrieves the type of this route.
	*
	* @return The type of this route; one of the {@code RTN_xxx} constants defined in this class.
	*/
	@RouteType
	public int getType() {
	return mType;
	}

	/**
	* Retrieves the MTU size for this route.
	*
	* @return The MTU size, or 0 if it has not been set.
	* @hide
	*/
	@SystemApi
	public int getMtu() {
	return mMtu;
	}

	/**
	* Indicates if this route is a default route (ie, has no destination specified).
	*
	* @return {@code true} if the destination has a prefix length of 0.
	*/
	public boolean isDefaultRoute() {
	return mType == RTN_UNICAST && mDestination.getPrefixLength() == 0;
	}

	/**
	* Indicates if this route is an unreachable default route.
	*
	* @return {@code true} if it's an unreachable route with prefix length of 0.
	* @hide
	*/
	private boolean isUnreachableDefaultRoute() {
	return mType == RTN_UNREACHABLE && mDestination.getPrefixLength() == 0;
	}

	/**
	* Indicates if this route is an IPv4 default route.
	* @hide
	*/
	public boolean isIPv4Default() {
	return isDefaultRoute() && mDestination.getAddress() instanceof Inet4Address;
	}

	/**
	* Indicates if this route is an IPv4 unreachable default route.
	* @hide
	*/
	public boolean isIPv4UnreachableDefault() {
	return isUnreachableDefaultRoute() && mDestination.getAddress() instanceof Inet4Address;
	}

	/**
	* Indicates if this route is an IPv6 default route.
	* @hide
	*/
	public boolean isIPv6Default() {
	return isDefaultRoute() && mDestination.getAddress() instanceof Inet6Address;
	}

	/**
	* Indicates if this route is an IPv6 unreachable default route.
	* @hide
	*/
	public boolean isIPv6UnreachableDefault() {
	return isUnreachableDefaultRoute() && mDestination.getAddress() instanceof Inet6Address;
	}

	/**
	* Indicates if this route is a host route (ie, matches only a single host address).
	*
	* @return {@code true} if the destination has a prefix length of 32 or 128 for IPv4 or IPv6,
	* respectively.
	* @hide
	*/
	public boolean isHostRoute() {
	return mIsHost;
	}

	/**
	* Indicates if this route has a next hop ({@code true}) or is directly-connected
	* ({@code false}).
	*
	* @return {@code true} if a gateway is specified
	*/
	public boolean hasGateway() {
	return mHasGateway;
	}

	/**
	* Determines whether the destination and prefix of this route includes the specified
	* address.
	*
	* @param destination A {@link InetAddress} to test to see if it would match this route.
	* @return {@code true} if the destination and prefix length cover the given address.
	*/
	public boolean matches(InetAddress destination) {
	return mDestination.contains(destination);
	}

	/**
	* 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
	*
	* @hide
	*/
	@UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
	@Nullable
	public static RouteInfo selectBestRoute(Collection<RouteInfo> routes, InetAddress dest) {
	return NetUtils.selectBestRoute(routes, dest);
	}

	/**
	* Returns a human-readable description of this object.
	*/
	public String toString() {
	String val = "";
	if (mDestination != null) val = mDestination.toString();
	if (mType == RTN_UNREACHABLE) {
	val += " unreachable";
	} else if (mType == RTN_THROW) {
	val += " throw";
	} else {
	val += " ->";
	if (mGateway != null) val += " " + mGateway.getHostAddress();
	if (mInterface != null) val += " " + mInterface;
	if (mType != RTN_UNICAST) {
	val += " unknown type " + mType;
	}
	}
	val += " mtu " + mMtu;
	return val;
	}

	/**
	* Compares this RouteInfo object against the specified object and indicates if they are equal.
	* @return {@code true} if the objects are equal, {@code false} otherwise.
	*/
	public boolean equals(@Nullable Object obj) {
	if (this == obj) return true;

	if (!(obj instanceof RouteInfo)) return false;

	RouteInfo target = (RouteInfo) obj;

	return Objects.equals(mDestination, target.getDestination()) &&
	Objects.equals(mGateway, target.getGateway()) &&
	Objects.equals(mInterface, target.getInterface()) &&
	mType == target.getType() && mMtu == target.getMtu();
	}

	/**
	* A helper class that contains the destination, the gateway and the interface in a
	* {@code RouteInfo}, used by {@link ConnectivityService#updateRoutes} or
	* {@link LinkProperties#addRoute} to calculate the list to be updated.
	* {@code RouteInfo} objects with different interfaces are treated as different routes because
	* usually on Android different interfaces use different routing tables, and moving a route
	* to a new routing table never constitutes an update, but is always a remove and an add.
	*
	* @hide
	*/
	public static class RouteKey {
	@NonNull private final IpPrefix mDestination;
	@Nullable private final InetAddress mGateway;
	@Nullable private final String mInterface;

	RouteKey(@NonNull IpPrefix destination, @Nullable InetAddress gateway,
	@Nullable String iface) {
	mDestination = destination;
	mGateway = gateway;
	mInterface = iface;
	}

	@Override
	public boolean equals(@Nullable Object o) {
	if (!(o instanceof RouteKey)) {
	return false;
	}
	RouteKey p = (RouteKey) o;
	// No need to do anything special for scoped addresses. Inet6Address#equals does not
	// consider the scope ID, but the route IPCs (e.g., RoutingCoordinatorManager#addRoute)
	// and the kernel ignore scoped addresses both in the prefix and in the nexthop and only
	// look at RTA_OIF.
	return Objects.equals(p.mDestination, mDestination)
	&& Objects.equals(p.mGateway, mGateway)
	&& Objects.equals(p.mInterface, mInterface);
	}

	@Override
	public int hashCode() {
	return Objects.hash(mDestination, mGateway, mInterface);
	}
	}

	/**
	* Get {@code RouteKey} of this {@code RouteInfo}.
	* @return a {@code RouteKey} object.
	*
	* @hide
	*/
	@NonNull
	public RouteKey getRouteKey() {
	return new RouteKey(mDestination, mGateway, mInterface);
	}

	/**
	* Returns a hashcode for this <code>RouteInfo</code> object.
	*/
	public int hashCode() {
	return (mDestination.hashCode() * 41)
	+ (mGateway == null ? 0 :mGateway.hashCode() * 47)
	+ (mInterface == null ? 0 :mInterface.hashCode() * 67)
	+ (mType * 71) + (mMtu * 89);
	}

	/**
	* Implement the Parcelable interface
	*/
	public int describeContents() {
	return 0;
	}

	/**
	* Implement the Parcelable interface
	*/
	public void writeToParcel(Parcel dest, int flags) {
	dest.writeParcelable(mDestination, flags);
	byte[] gatewayBytes = (mGateway == null) ? null : mGateway.getAddress();
	dest.writeByteArray(gatewayBytes);
	dest.writeString(mInterface);
	dest.writeInt(mType);
	dest.writeInt(mMtu);
	}

	/**
	* Implement the Parcelable interface.
	*/
	public static final @android.annotation.NonNull Creator<RouteInfo> CREATOR =
	new Creator<RouteInfo>() {
	public RouteInfo createFromParcel(Parcel in) {
	IpPrefix dest = in.readParcelable(null);

	InetAddress gateway = null;
	byte[] addr = in.createByteArray();
	try {
	gateway = InetAddress.getByAddress(addr);
	} catch (UnknownHostException e) {}

	String iface = in.readString();
	int type = in.readInt();
	int mtu = in.readInt();

	return new RouteInfo(dest, gateway, iface, type, mtu);
	}

	public RouteInfo[] newArray(int size) {
	return new RouteInfo[size];
	}
	};
	}