Have ConnectivityService install packet filters when possible

Listen for ICMP6 router advertisements on networks that support
packet filters.  Construct packet filters and install them to
ignore redundant future ICMP6 router advertisements.

Bug: 26238573
Change-Id: If78300b9fda257c21f3ee6533e1da7de9f897cb4

3 files changed, 53 insertions, 0 deletions

diff --git a/core/java/android/net/NetworkAgent.java b/core/java/android/net/NetworkAgent.java
index 20c216826531..9e360e11bf8b 100644
--- a/core/java/android/net/NetworkAgent.java
+++ b/core/java/android/net/NetworkAgent.java
@@ -200,6 +200,14 @@ public abstract class NetworkAgent extends Handler {
      */
     public static final int CMD_PREVENT_AUTOMATIC_RECONNECT = BASE + 15;
 
+    /**
+     * Sent by ConnectivityService to the NetworkAgent to install an APF program in the network
+     * chipset for use to filter packets.
+     *
+     * obj = byte[] containing the APF program bytecode.
+     */
+    public static final int CMD_PUSH_APF_PROGRAM = BASE + 16;
+
     public NetworkAgent(Looper looper, Context context, String logTag, NetworkInfo ni,
             NetworkCapabilities nc, LinkProperties lp, int score) {
         this(looper, context, logTag, ni, nc, lp, score, null);
@@ -319,6 +327,10 @@ public abstract class NetworkAgent extends Handler {
                 preventAutomaticReconnect();
                 break;
             }
+            case CMD_PUSH_APF_PROGRAM: {
+                installPacketFilter((byte[]) msg.obj);
+                break;
+            }
         }
     }
 
@@ -494,6 +506,15 @@ public abstract class NetworkAgent extends Handler {
     protected void preventAutomaticReconnect() {
     }
 
+    /**
+     * Install a packet filter.
+     * @param filter an APF program to filter incoming packets.
+     * @return {@code true} if filter successfully installed, {@code false} otherwise.
+     */
+    protected boolean installPacketFilter(byte[] filter) {
+        return false;
+    }
+
     protected void log(String s) {
         Log.d(LOG_TAG, "NetworkAgent: " + s);
     }
diff --git a/core/java/android/net/NetworkMisc.java b/core/java/android/net/NetworkMisc.java
index 5511a248b6aa..748699eff4cf 100644
--- a/core/java/android/net/NetworkMisc.java
+++ b/core/java/android/net/NetworkMisc.java
@@ -56,6 +56,22 @@ public class NetworkMisc implements Parcelable {
      */
     public String subscriberId;
 
+    /**
+     * Version of APF instruction set supported for packet filtering. 0 indicates no support for
+     * packet filtering using APF programs.
+     */
+    public int apfVersionSupported;
+
+    /**
+     * Maximum size of APF program allowed.
+     */
+    public int maximumApfProgramSize;
+
+    /**
+     * Format of packets passed to APF filter. Should be one of ARPHRD_*
+     */
+    public int apfPacketFormat;
+
     public NetworkMisc() {
     }
 
@@ -65,6 +81,9 @@ public class NetworkMisc implements Parcelable {
             explicitlySelected = nm.explicitlySelected;
             acceptUnvalidated = nm.acceptUnvalidated;
             subscriberId = nm.subscriberId;
+            apfVersionSupported = nm.apfVersionSupported;
+            maximumApfProgramSize = nm.maximumApfProgramSize;
+            apfPacketFormat = nm.apfPacketFormat;
         }
     }
 
@@ -79,6 +98,9 @@ public class NetworkMisc implements Parcelable {
         out.writeInt(explicitlySelected ? 1 : 0);
         out.writeInt(acceptUnvalidated ? 1 : 0);
         out.writeString(subscriberId);
+        out.writeInt(apfVersionSupported);
+        out.writeInt(maximumApfProgramSize);
+        out.writeInt(apfPacketFormat);
     }
 
     public static final Creator<NetworkMisc> CREATOR = new Creator<NetworkMisc>() {
@@ -89,6 +111,9 @@ public class NetworkMisc implements Parcelable {
             networkMisc.explicitlySelected = in.readInt() != 0;
             networkMisc.acceptUnvalidated = in.readInt() != 0;
             networkMisc.subscriberId = in.readString();
+            networkMisc.apfVersionSupported = in.readInt();
+            networkMisc.maximumApfProgramSize = in.readInt();
+            networkMisc.apfPacketFormat = in.readInt();
             return networkMisc;
         }
 
diff --git a/core/java/android/net/NetworkUtils.java b/core/java/android/net/NetworkUtils.java
index c6d919f4d77e..555032d522bf 100644
--- a/core/java/android/net/NetworkUtils.java
+++ b/core/java/android/net/NetworkUtils.java
@@ -62,6 +62,13 @@ public class NetworkUtils {
     public native static void attachDhcpFilter(FileDescriptor fd) throws SocketException;
 
     /**
+     * Attaches a socket filter that accepts ICMP6 router advertisement packets to the given socket.
+     * @param fd the socket's {@link FileDescriptor}.
+     * @param packetType the hardware address type, one of ARPHRD_*.
+     */
+    public native static void attachRaFilter(FileDescriptor fd, int packetType) throws SocketException;
+
+    /**
      * Binds the current process to the network designated by {@code netId}.  All sockets created
      * in the future (and not explicitly bound via a bound {@link SocketFactory} (see
      * {@link Network#getSocketFactory}) will be bound to this network.  Note that if this