Refactor RouterAdvertisementDaemon with FdEventsReader
This patch changes the implementation of UnicastResponder in the
RouterAdvertisementDaemon with FdEventsReader. The change includes
replacing Thread with HandlerThread, create socket in non-blocking
mode (required by FdEventsReader) and use FdEventsReader to listen
to the solicited RS packets. Two commands (CMD_START & CMD_STOP)
were added to control the lifecycle of the FdEventsReader.
Bug: 246928127
Test: atest TetheringPrivilegedTests TetheringIntegrationTests \
TetheringTests
Test: Enable WiFi hotspot and connected with another Pixel client:
1. Tcpdump on the Pixel client, checking the RA packets
2. Verify IPv6 addresses were configured
3. ping6 2001:4860:4860::64
Change-Id: I6e89903df90864e3bb34d498e353d6f87193e9d6
diff --git a/Tethering/src/android/net/ip/RouterAdvertisementDaemon.java b/Tethering/src/android/net/ip/RouterAdvertisementDaemon.java
index 50d6c4b..d8779b8 100644
--- a/Tethering/src/android/net/ip/RouterAdvertisementDaemon.java
+++ b/Tethering/src/android/net/ip/RouterAdvertisementDaemon.java
@@ -18,6 +18,7 @@
import static android.system.OsConstants.AF_INET6;
import static android.system.OsConstants.IPPROTO_ICMPV6;
+import static android.system.OsConstants.SOCK_NONBLOCK;
import static android.system.OsConstants.SOCK_RAW;
import static android.system.OsConstants.SOL_SOCKET;
import static android.system.OsConstants.SO_SNDTIMEO;
@@ -38,12 +39,19 @@
import android.net.MacAddress;
import android.net.TrafficStats;
import android.net.util.SocketUtils;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.Looper;
+import android.os.Message;
import android.system.ErrnoException;
import android.system.Os;
import android.system.StructTimeval;
import android.util.Log;
+import androidx.annotation.NonNull;
+
import com.android.internal.annotations.GuardedBy;
+import com.android.net.module.util.FdEventsReader;
import com.android.net.module.util.InterfaceParams;
import com.android.net.module.util.structs.Icmpv6Header;
import com.android.net.module.util.structs.LlaOption;
@@ -103,6 +111,10 @@
private static final int DAY_IN_SECONDS = 86_400;
+ // Commands for IpServer to control RouterAdvertisementDaemon
+ private static final int CMD_START = 1;
+ private static final int CMD_STOP = 2;
+
private final InterfaceParams mInterface;
private final InetSocketAddress mAllNodes;
@@ -120,9 +132,13 @@
@GuardedBy("mLock")
private RaParams mRaParams;
+ // To be accessed only from RaMessageHandler
+ private RsPacketListener mRsPacketListener;
+
private volatile FileDescriptor mSocket;
private volatile MulticastTransmitter mMulticastTransmitter;
- private volatile UnicastResponder mUnicastResponder;
+ private volatile RaMessageHandler mRaMessageHandler;
+ private volatile HandlerThread mRaHandlerThread;
/** Encapsulate the RA parameters for RouterAdvertisementDaemon.*/
public static class RaParams {
@@ -244,6 +260,74 @@
}
}
+ private class RaMessageHandler extends Handler {
+ RaMessageHandler(Looper looper) {
+ super(looper);
+ }
+
+ @Override
+ public void handleMessage(Message msg) {
+ switch (msg.what) {
+ case CMD_START:
+ mRsPacketListener = new RsPacketListener(this);
+ mRsPacketListener.start();
+ break;
+ case CMD_STOP:
+ if (mRsPacketListener != null) {
+ mRsPacketListener.stop();
+ mRsPacketListener = null;
+ }
+ break;
+ default:
+ Log.e(TAG, "Unknown message, cmd = " + String.valueOf(msg.what));
+ break;
+ }
+ }
+ }
+
+ private class RsPacketListener extends FdEventsReader<RsPacketListener.RecvBuffer> {
+ private static final class RecvBuffer {
+ // The recycled buffer for receiving Router Solicitations from clients.
+ // If the RS is larger than IPV6_MIN_MTU the packets are truncated.
+ // This is fine since currently only byte 0 is examined anyway.
+ final byte[] mBytes = new byte[IPV6_MIN_MTU];
+ final InetSocketAddress mSrcAddr = new InetSocketAddress(0);
+ }
+
+ RsPacketListener(@NonNull Handler handler) {
+ super(handler, new RecvBuffer());
+ }
+
+ @Override
+ protected int recvBufSize(@NonNull RecvBuffer buffer) {
+ return buffer.mBytes.length;
+ }
+
+ @Override
+ protected FileDescriptor createFd() {
+ return mSocket;
+ }
+
+ @Override
+ protected int readPacket(@NonNull FileDescriptor fd, @NonNull RecvBuffer buffer)
+ throws Exception {
+ return Os.recvfrom(
+ fd, buffer.mBytes, 0, buffer.mBytes.length, 0 /* flags */, buffer.mSrcAddr);
+ }
+
+ @Override
+ protected final void handlePacket(@NonNull RecvBuffer buffer, int length) {
+ // Do the least possible amount of validations.
+ if (buffer.mSrcAddr == null
+ || length <= 0
+ || buffer.mBytes[0] != asByte(ICMPV6_ROUTER_SOLICITATION)) {
+ return;
+ }
+
+ maybeSendRA(buffer.mSrcAddr);
+ }
+ }
+
public RouterAdvertisementDaemon(InterfaceParams ifParams) {
mInterface = ifParams;
mAllNodes = new InetSocketAddress(getAllNodesForScopeId(mInterface.index), 0);
@@ -274,26 +358,36 @@
/** Start router advertisement daemon. */
public boolean start() {
if (!createSocket()) {
+ Log.e(TAG, "Failed to start RouterAdvertisementDaemon.");
return false;
}
mMulticastTransmitter = new MulticastTransmitter();
mMulticastTransmitter.start();
- mUnicastResponder = new UnicastResponder();
- mUnicastResponder.start();
+ mRaHandlerThread = new HandlerThread(TAG);
+ mRaHandlerThread.start();
+ mRaMessageHandler = new RaMessageHandler(mRaHandlerThread.getLooper());
- return true;
+ return sendMessage(CMD_START);
}
/** Stop router advertisement daemon. */
public void stop() {
+ if (!sendMessage(CMD_STOP)) {
+ Log.e(TAG, "RouterAdvertisementDaemon has been stopped or was never started.");
+ return;
+ }
+
+ mRaHandlerThread.quitSafely();
+ mRaHandlerThread = null;
+ mRaMessageHandler = null;
+
closeSocket();
// Wake up mMulticastTransmitter thread to interrupt a potential 1 day sleep before
// the thread's termination.
maybeNotifyMulticastTransmitter();
mMulticastTransmitter = null;
- mUnicastResponder = null;
}
@GuardedBy("mLock")
@@ -503,7 +597,7 @@
final int oldTag = TrafficStats.getAndSetThreadStatsTag(TAG_SYSTEM_NEIGHBOR);
try {
- mSocket = Os.socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
+ mSocket = Os.socket(AF_INET6, SOCK_RAW | SOCK_NONBLOCK, IPPROTO_ICMPV6);
// Setting SNDTIMEO is purely for defensive purposes.
Os.setsockoptTimeval(
mSocket, SOL_SOCKET, SO_SNDTIMEO, StructTimeval.fromMillis(send_timout_ms));
@@ -565,34 +659,12 @@
}
}
- private final class UnicastResponder extends Thread {
- private final InetSocketAddress mSolicitor = new InetSocketAddress(0);
- // The recycled buffer for receiving Router Solicitations from clients.
- // If the RS is larger than IPV6_MIN_MTU the packets are truncated.
- // This is fine since currently only byte 0 is examined anyway.
- private final byte[] mSolicitation = new byte[IPV6_MIN_MTU];
-
- @Override
- public void run() {
- while (isSocketValid()) {
- try {
- // Blocking receive.
- final int rval = Os.recvfrom(
- mSocket, mSolicitation, 0, mSolicitation.length, 0, mSolicitor);
- // Do the least possible amount of validation.
- if (rval < 1 || mSolicitation[0] != asByte(ICMPV6_ROUTER_SOLICITATION)) {
- continue;
- }
- } catch (ErrnoException | SocketException e) {
- if (isSocketValid()) {
- Log.e(TAG, "recvfrom error: " + e);
- }
- continue;
- }
-
- maybeSendRA(mSolicitor);
- }
+ private boolean sendMessage(int cmd) {
+ if (mRaMessageHandler == null) {
+ return false;
}
+
+ return mRaMessageHandler.sendMessage(Message.obtain(mRaMessageHandler, cmd));
}
// TODO: Consider moving this to run on a provided Looper as a Handler,