mtu: Add MTU parameter to Routes

- Change route to update existing route
- MTU parameter added to AddRoute

Bug: 142892223
Test: unit test
Change-Id: I2164808ef628eb7c12e875f0bde7f5151bf6a5b5
Merged-In: Ie339d0cee5be12c2232a4631fed61219a0facc64
(cherry picked from commit e521f07e8b03102f1b510a3fb401993513d9c127)

core/java/android/net/LinkProperties.java

@@ -674,17 +674,29 @@ public final class LinkProperties implements Parcelable {
             route.getDestination(),
             route.getGateway(),
             mIfaceName,
-            route.getType());
+            route.getType(),
+            route.getMtu());
+    }
+
+    private int findRouteIndexByDestination(RouteInfo route) {
+        for (int i = 0; i < mRoutes.size(); i++) {
+            if (mRoutes.get(i).isSameDestinationAs(route)) {
+                return i;
+            }
+        }
+        return -1;
     }
 
     /**
-     * Adds a {@link RouteInfo} to this {@code LinkProperties}, if not present. If the
-     * {@link RouteInfo} had an interface name set and that differs from the interface set for this
-     * {@code LinkProperties} an {@link IllegalArgumentException} will be thrown.  The proper
+     * Adds a {@link RouteInfo} to this {@code LinkProperties}, if a {@link RouteInfo}
+     * with the same destination exists with different properties (e.g., different MTU),
+     * it will be updated. If the {@link RouteInfo} had an interface name set and
+     * that differs from the interface set for this {@code LinkProperties} an
+     * {@link IllegalArgumentException} will be thrown.  The proper
      * course is to add either un-named or properly named {@link RouteInfo}.
      *
      * @param route A {@link RouteInfo} to add to this object.
-     * @return {@code false} if the route was already present, {@code true} if it was added.
+     * @return {@code true} was added or updated, false otherwise.
      */
     public boolean addRoute(@NonNull RouteInfo route) {
         String routeIface = route.getInterface();
@@ -694,11 +706,20 @@ public final class LinkProperties implements Parcelable {
                             + " vs. " + mIfaceName);
         }
         route = routeWithInterface(route);
-        if (!mRoutes.contains(route)) {
+
+        int i = findRouteIndexByDestination(route);
+        if (i == -1) {
+            // Route was not present. Add it.
             mRoutes.add(route);
             return true;
+        } else if (mRoutes.get(i).equals(route)) {
+            // Route was present and has same properties. Do nothing.
+            return false;
+        } else {
+            // Route was present and has different properties. Update it.
+            mRoutes.set(i, route);
+            return true;
         }
-        return false;
     }
 
     /**
@@ -706,6 +727,7 @@ public final class LinkProperties implements Parcelable {
      * specify an interface and the interface must match the interface of this
      * {@code LinkProperties}, or it will not be removed.
      *
+     * @param route A {@link RouteInfo} specifying the route to remove.
      * @return {@code true} if the route was removed, {@code false} if it was not present.
      *
      * @hide

core/java/android/net/RouteInfo.java

@@ -526,6 +526,26 @@ public final class RouteInfo implements Parcelable {
                 mType == target.getType() && mMtu == target.getMtu();
     }
 
+    /**
+     * Compares this RouteInfo object against the specified object and indicates if the
+     * destinations of both routes are equal.
+     * @return {@code true} if the route destinations are equal, {@code false} otherwise.
+     *
+     * @hide
+     */
+    public boolean isSameDestinationAs(@Nullable Object obj) {
+        if (this == obj) return true;
+
+        if (!(obj instanceof RouteInfo)) return false;
+
+        RouteInfo target = (RouteInfo) obj;
+
+        if (Objects.equals(mDestination, target.getDestination())) {
+            return true;
+        }
+        return false;
+    }
+
     /**
      *  Returns a hashcode for this <code>RouteInfo</code> object.
      */