Minor changes to the LinkAddress API docs.

1. Rename getNetworkPrefixLength to getPrefixLength. Update all
   callers in frameworks/base and add a shim method and a TODO
   for the rest.
2. @hide isSameAddressAs. It doesn't add much, and it's just
   one-liner that callers can implement if they want.
3. Fix the alignment of the initial paragraph (<ul> should have
   been </ul>).
4. Remove the documentation that talks about creating
   LinkAddresses, since there's no public API for creating them.

With these changes I think LinkAddress is fine as a public API.

Bug: 15142362
Change-Id: Iaf3b1db577745bb68a9e1dd7f96d666dd3f3ec7c
(cherry picked from commit 9ab53650cfcd91a2a151b44b3fd1381841f76269)
diff --git a/api/current.txt b/api/current.txt
index 636e201c..ad91b0a 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -16021,9 +16021,8 @@
     method public int describeContents();
     method public java.net.InetAddress getAddress();
     method public int getFlags();
-    method public int getNetworkPrefixLength();
+    method public int getPrefixLength();
     method public int getScope();
-    method public boolean isSameAddressAs(android.net.LinkAddress);
     method public void writeToParcel(android.os.Parcel, int);
   }
 
diff --git a/core/java/android/net/LinkAddress.java b/core/java/android/net/LinkAddress.java
index d07c0b61..5246078 100644
--- a/core/java/android/net/LinkAddress.java
+++ b/core/java/android/net/LinkAddress.java
@@ -39,18 +39,13 @@
  * <ul>
  * <li>An IP address and prefix length (e.g., {@code 2001:db8::1/64} or {@code 192.0.2.1/24}).
  * The address must be unicast, as multicast addresses cannot be assigned to interfaces.
- * <li>Address flags: A bitmask of {@code IFA_F_*} values representing properties
- * of the address.
- * <li>Address scope: An integer defining the scope in which the address is unique (e.g.,
- * {@code RT_SCOPE_LINK} or {@code RT_SCOPE_SITE}).
- * <ul>
- *<p>
- * When constructing a {@code LinkAddress}, the IP address and prefix are required. The flags and
- * scope are optional. If they are not specified, the flags are set to zero, and the scope will be
- * determined based on the IP address (e.g., link-local addresses will be created with a scope of
- * {@code RT_SCOPE_LINK}, global addresses with {@code RT_SCOPE_UNIVERSE},
- * etc.) If they are specified, they are not checked for validity.
- *
+ * <li>Address flags: A bitmask of {@code OsConstants.IFA_F_*} values representing properties
+ * of the address (e.g., {@code android.system.OsConstants.IFA_F_OPTIMISTIC}).
+ * <li>Address scope: One of the {@code OsConstants.IFA_F_*} values; defines the scope in which
+ * the address is unique (e.g.,
+ * {@code android.system.OsConstants.RT_SCOPE_LINK} or
+ * {@code android.system.OsConstants.RT_SCOPE_UNIVERSE}).
+ * </ul>
  */
 public class LinkAddress implements Parcelable {
     /**
@@ -202,7 +197,9 @@
 
     /**
      * Compares this {@code LinkAddress} instance against {@code obj}. Two addresses are equal if
-     * their address, prefix length, flags and scope are equal.
+     * their address, prefix length, flags and scope are equal. Thus, for example, two addresses
+     * that have the same address and prefix length are not equal if one of them is deprecated and
+     * the other is not.
      *
      * @param obj the object to be tested for equality.
      * @return {@code true} if both objects are equal, {@code false} otherwise.
@@ -236,6 +233,7 @@
      * @param other the {@code LinkAddress} to compare to.
      * @return {@code true} if both objects have the same address and prefix length, {@code false}
      * otherwise.
+     * @hide
      */
     public boolean isSameAddressAs(LinkAddress other) {
         return address.equals(other.address) && prefixLength == other.prefixLength;
@@ -251,11 +249,20 @@
     /**
      * Returns the prefix length of this {@code LinkAddress}.
      */
-    public int getNetworkPrefixLength() {
+    public int getPrefixLength() {
         return prefixLength;
     }
 
     /**
+     * Returns the prefix length of this {@code LinkAddress}.
+     * TODO: Delete all callers and remove in favour of getPrefixLength().
+     * @hide
+     */
+    public int getNetworkPrefixLength() {
+        return getPrefixLength();
+    }
+
+    /**
      * Returns the flags of this {@code LinkAddress}.
      */
     public int getFlags() {
diff --git a/core/java/android/net/RouteInfo.java b/core/java/android/net/RouteInfo.java
index ad8e4f7..0f35096 100644
--- a/core/java/android/net/RouteInfo.java
+++ b/core/java/android/net/RouteInfo.java
@@ -105,7 +105,7 @@
         mHasGateway = (!gateway.isAnyLocalAddress());
 
         mDestination = new LinkAddress(NetworkUtils.getNetworkPart(destination.getAddress(),
-                destination.getNetworkPrefixLength()), destination.getNetworkPrefixLength());
+                destination.getPrefixLength()), destination.getPrefixLength());
         if ((destination.getAddress() instanceof Inet4Address &&
                  (gateway instanceof Inet4Address == false)) ||
                 (destination.getAddress() instanceof Inet6Address &&
@@ -176,18 +176,18 @@
 
     private boolean isHost() {
         return (mDestination.getAddress() instanceof Inet4Address &&
-                mDestination.getNetworkPrefixLength() == 32) ||
+                mDestination.getPrefixLength() == 32) ||
                (mDestination.getAddress() instanceof Inet6Address &&
-                mDestination.getNetworkPrefixLength() == 128);
+                mDestination.getPrefixLength() == 128);
     }
 
     private boolean isDefault() {
         boolean val = false;
         if (mGateway != null) {
             if (mGateway instanceof Inet4Address) {
-                val = (mDestination == null || mDestination.getNetworkPrefixLength() == 0);
+                val = (mDestination == null || mDestination.getPrefixLength() == 0);
             } else {
-                val = (mDestination == null || mDestination.getNetworkPrefixLength() == 0);
+                val = (mDestination == null || mDestination.getPrefixLength() == 0);
             }
         }
         return val;
@@ -263,7 +263,7 @@
 
         // match the route destination and destination with prefix length
         InetAddress dstNet = NetworkUtils.getNetworkPart(destination,
-                mDestination.getNetworkPrefixLength());
+                mDestination.getPrefixLength());
 
         return mDestination.getAddress().equals(dstNet);
     }
@@ -285,8 +285,8 @@
         for (RouteInfo route : routes) {
             if (NetworkUtils.addressTypeMatches(route.mDestination.getAddress(), dest)) {
                 if ((bestRoute != null) &&
-                        (bestRoute.mDestination.getNetworkPrefixLength() >=
-                        route.mDestination.getNetworkPrefixLength())) {
+                        (bestRoute.mDestination.getPrefixLength() >=
+                        route.mDestination.getPrefixLength())) {
                     continue;
                 }
                 if (route.matches(dest)) bestRoute = route;
@@ -339,7 +339,7 @@
         } else {
             dest.writeByte((byte) 1);
             dest.writeByteArray(mDestination.getAddress().getAddress());
-            dest.writeInt(mDestination.getNetworkPrefixLength());
+            dest.writeInt(mDestination.getPrefixLength());
         }
 
         if (mGateway == null) {
diff --git a/core/tests/coretests/src/android/net/LinkAddressTest.java b/core/tests/coretests/src/android/net/LinkAddressTest.java
index bccf556..814ecdd 100644
--- a/core/tests/coretests/src/android/net/LinkAddressTest.java
+++ b/core/tests/coretests/src/android/net/LinkAddressTest.java
@@ -56,26 +56,26 @@
         // Valid addresses work as expected.
         address = new LinkAddress(V4_ADDRESS, 25);
         assertEquals(V4_ADDRESS, address.getAddress());
-        assertEquals(25, address.getNetworkPrefixLength());
+        assertEquals(25, address.getPrefixLength());
         assertEquals(0, address.getFlags());
         assertEquals(RT_SCOPE_UNIVERSE, address.getScope());
 
         address = new LinkAddress(V6_ADDRESS, 127);
         assertEquals(V6_ADDRESS, address.getAddress());
-        assertEquals(127, address.getNetworkPrefixLength());
+        assertEquals(127, address.getPrefixLength());
         assertEquals(0, address.getFlags());
         assertEquals(RT_SCOPE_UNIVERSE, address.getScope());
 
         // Nonsensical flags/scopes or combinations thereof are acceptable.
         address = new LinkAddress(V6 + "/64", IFA_F_DEPRECATED | IFA_F_PERMANENT, RT_SCOPE_LINK);
         assertEquals(V6_ADDRESS, address.getAddress());
-        assertEquals(64, address.getNetworkPrefixLength());
+        assertEquals(64, address.getPrefixLength());
         assertEquals(IFA_F_DEPRECATED | IFA_F_PERMANENT, address.getFlags());
         assertEquals(RT_SCOPE_LINK, address.getScope());
 
         address = new LinkAddress(V4 + "/23", 123, 456);
         assertEquals(V4_ADDRESS, address.getAddress());
-        assertEquals(23, address.getNetworkPrefixLength());
+        assertEquals(23, address.getPrefixLength());
         assertEquals(123, address.getFlags());
         assertEquals(456, address.getScope());
 
@@ -94,10 +94,10 @@
         }
 
         assertEquals(NetworkUtils.numericToInetAddress("127.0.0.1"), ipv4Loopback.getAddress());
-        assertEquals(8, ipv4Loopback.getNetworkPrefixLength());
+        assertEquals(8, ipv4Loopback.getPrefixLength());
 
         assertEquals(NetworkUtils.numericToInetAddress("::1"), ipv6Loopback.getAddress());
-        assertEquals(128, ipv6Loopback.getNetworkPrefixLength());
+        assertEquals(128, ipv6Loopback.getPrefixLength());
 
         // Null addresses are rejected.
         try {
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index bd45761..de99aec 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -1669,7 +1669,7 @@
                         continue;
                     }
 
-                    int prefix = destination.getNetworkPrefixLength();
+                    int prefix = destination.getPrefixLength();
                     InetAddress addrMasked = NetworkUtils.getNetworkPart(address, prefix);
                     InetAddress destMasked = NetworkUtils.getNetworkPart(destination.getAddress(),
                             prefix);
diff --git a/services/core/java/com/android/server/NetworkManagementService.java b/services/core/java/com/android/server/NetworkManagementService.java
index eefe8da..0b711ee 100644
--- a/services/core/java/com/android/server/NetworkManagementService.java
+++ b/services/core/java/com/android/server/NetworkManagementService.java
@@ -795,7 +795,7 @@
 
         final Command cmd = new Command("interface", "setcfg", iface,
                 linkAddr.getAddress().getHostAddress(),
-                linkAddr.getNetworkPrefixLength());
+                linkAddr.getPrefixLength());
         for (String flag : cfg.getFlags()) {
             cmd.appendArg(flag);
         }
@@ -884,7 +884,7 @@
         // create triplet: interface dest-ip-addr/prefixlength gateway-ip-addr
         final LinkAddress la = route.getDestination();
         cmd.appendArg(route.getInterface());
-        cmd.appendArg(la.getAddress().getHostAddress() + "/" + la.getNetworkPrefixLength());
+        cmd.appendArg(la.getAddress().getHostAddress() + "/" + la.getPrefixLength());
         if (route.hasGateway()) {
             cmd.appendArg(route.getGateway().getHostAddress());
         }
@@ -1699,7 +1699,7 @@
         try {
             LinkAddress dest = route.getDestination();
             mConnector.execute("interface", "fwmark", "route", "add", iface,
-                    dest.getAddress().getHostAddress(), dest.getNetworkPrefixLength());
+                    dest.getAddress().getHostAddress(), dest.getPrefixLength());
         } catch (NativeDaemonConnectorException e) {
             throw e.rethrowAsParcelableException();
         }
@@ -1711,7 +1711,7 @@
         try {
             LinkAddress dest = route.getDestination();
             mConnector.execute("interface", "fwmark", "route", "remove", iface,
-                    dest.getAddress().getHostAddress(), dest.getNetworkPrefixLength());
+                    dest.getAddress().getHostAddress(), dest.getPrefixLength());
         } catch (NativeDaemonConnectorException e) {
             throw e.rethrowAsParcelableException();
         }
@@ -2000,7 +2000,7 @@
         // create triplet: interface dest-ip-addr/prefixlength gateway-ip-addr
         final LinkAddress la = routeInfo.getDestination();
         cmd.appendArg(routeInfo.getInterface());
-        cmd.appendArg(la.getAddress().getHostAddress() + "/" + la.getNetworkPrefixLength());
+        cmd.appendArg(la.getAddress().getHostAddress() + "/" + la.getPrefixLength());
         if (routeInfo.hasGateway()) {
             cmd.appendArg(routeInfo.getGateway().getHostAddress());
         }
diff --git a/services/core/java/com/android/server/net/IpConfigStore.java b/services/core/java/com/android/server/net/IpConfigStore.java
index aee7679..dc4dc2e 100644
--- a/services/core/java/com/android/server/net/IpConfigStore.java
+++ b/services/core/java/com/android/server/net/IpConfigStore.java
@@ -81,7 +81,7 @@
                     for (LinkAddress linkAddr : linkProperties.getLinkAddresses()) {
                         out.writeUTF(LINK_ADDRESS_KEY);
                         out.writeUTF(linkAddr.getAddress().getHostAddress());
-                        out.writeInt(linkAddr.getNetworkPrefixLength());
+                        out.writeInt(linkAddr.getPrefixLength());
                     }
                     for (RouteInfo route : linkProperties.getRoutes()) {
                         out.writeUTF(GATEWAY_KEY);
@@ -89,7 +89,7 @@
                         if (dest != null) {
                             out.writeInt(1);
                             out.writeUTF(dest.getAddress().getHostAddress());
-                            out.writeInt(dest.getNetworkPrefixLength());
+                            out.writeInt(dest.getPrefixLength());
                         } else {
                             out.writeInt(0);
                         }