| /* |
| * Copyright (C) 2017 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.ip; |
| |
| import static android.net.netlink.NetlinkConstants.RTM_DELNEIGH; |
| import static android.net.netlink.NetlinkConstants.hexify; |
| import static android.net.netlink.NetlinkConstants.stringForNlMsgType; |
| import static android.net.util.SocketUtils.makeNetlinkSocketAddress; |
| import static android.system.OsConstants.AF_NETLINK; |
| import static android.system.OsConstants.NETLINK_ROUTE; |
| import static android.system.OsConstants.SOCK_DGRAM; |
| import static android.system.OsConstants.SOCK_NONBLOCK; |
| |
| import android.net.MacAddress; |
| import android.net.netlink.NetlinkErrorMessage; |
| import android.net.netlink.NetlinkMessage; |
| import android.net.netlink.NetlinkSocket; |
| import android.net.netlink.RtNetlinkNeighborMessage; |
| import android.net.netlink.StructNdMsg; |
| import android.net.util.NetworkStackUtils; |
| import android.net.util.PacketReader; |
| import android.net.util.SharedLog; |
| import android.os.Handler; |
| import android.os.SystemClock; |
| import android.system.ErrnoException; |
| import android.system.Os; |
| import android.system.OsConstants; |
| import android.util.Log; |
| |
| import java.io.FileDescriptor; |
| import java.net.InetAddress; |
| import java.net.SocketAddress; |
| import java.net.SocketException; |
| import java.nio.ByteBuffer; |
| import java.nio.ByteOrder; |
| import java.util.StringJoiner; |
| |
| |
| /** |
| * IpNeighborMonitor. |
| * |
| * Monitors the kernel rtnetlink neighbor notifications and presents to callers |
| * NeighborEvents describing each event. Callers can provide a consumer instance |
| * to both filter (e.g. by interface index and IP address) and handle the |
| * generated NeighborEvents. |
| * |
| * @hide |
| */ |
| public class IpNeighborMonitor extends PacketReader { |
| private static final String TAG = IpNeighborMonitor.class.getSimpleName(); |
| private static final boolean DBG = false; |
| private static final boolean VDBG = false; |
| |
| /** |
| * Make the kernel perform neighbor reachability detection (IPv4 ARP or IPv6 ND) |
| * for the given IP address on the specified interface index. |
| * |
| * @return 0 if the request was successfully passed to the kernel; otherwise return |
| * a non-zero error code. |
| */ |
| public static int startKernelNeighborProbe(int ifIndex, InetAddress ip) { |
| final String msgSnippet = "probing ip=" + ip.getHostAddress() + "%" + ifIndex; |
| if (DBG) { Log.d(TAG, msgSnippet); } |
| |
| final byte[] msg = RtNetlinkNeighborMessage.newNewNeighborMessage( |
| 1, ip, StructNdMsg.NUD_PROBE, ifIndex, null); |
| |
| try { |
| NetlinkSocket.sendOneShotKernelMessage(NETLINK_ROUTE, msg); |
| } catch (ErrnoException e) { |
| Log.e(TAG, "Error " + msgSnippet + ": " + e); |
| return -e.errno; |
| } |
| |
| return 0; |
| } |
| |
| public static class NeighborEvent { |
| final long elapsedMs; |
| final short msgType; |
| final int ifindex; |
| final InetAddress ip; |
| final short nudState; |
| final MacAddress macAddr; |
| |
| public NeighborEvent(long elapsedMs, short msgType, int ifindex, InetAddress ip, |
| short nudState, MacAddress macAddr) { |
| this.elapsedMs = elapsedMs; |
| this.msgType = msgType; |
| this.ifindex = ifindex; |
| this.ip = ip; |
| this.nudState = nudState; |
| this.macAddr = macAddr; |
| } |
| |
| boolean isConnected() { |
| return (msgType != RTM_DELNEIGH) && StructNdMsg.isNudStateConnected(nudState); |
| } |
| |
| boolean isValid() { |
| return (msgType != RTM_DELNEIGH) && StructNdMsg.isNudStateValid(nudState); |
| } |
| |
| @Override |
| public String toString() { |
| final StringJoiner j = new StringJoiner(",", "NeighborEvent{", "}"); |
| return j.add("@" + elapsedMs) |
| .add(stringForNlMsgType(msgType)) |
| .add("if=" + ifindex) |
| .add(ip.getHostAddress()) |
| .add(StructNdMsg.stringForNudState(nudState)) |
| .add("[" + macAddr + "]") |
| .toString(); |
| } |
| } |
| |
| public interface NeighborEventConsumer { |
| // Every neighbor event received on the netlink socket is passed in |
| // here. Subclasses should filter for events of interest. |
| public void accept(NeighborEvent event); |
| } |
| |
| private final SharedLog mLog; |
| private final NeighborEventConsumer mConsumer; |
| |
| public IpNeighborMonitor(Handler h, SharedLog log, NeighborEventConsumer cb) { |
| super(h, NetlinkSocket.DEFAULT_RECV_BUFSIZE); |
| mLog = log.forSubComponent(TAG); |
| mConsumer = (cb != null) ? cb : (event) -> { /* discard */ }; |
| } |
| |
| @Override |
| protected FileDescriptor createFd() { |
| FileDescriptor fd = null; |
| |
| try { |
| fd = Os.socket(AF_NETLINK, SOCK_DGRAM | SOCK_NONBLOCK, NETLINK_ROUTE); |
| Os.bind(fd, makeNetlinkSocketAddress(0, OsConstants.RTMGRP_NEIGH)); |
| NetlinkSocket.connectToKernel(fd); |
| |
| if (VDBG) { |
| final SocketAddress nlAddr = Os.getsockname(fd); |
| Log.d(TAG, "bound to sockaddr_nl{" + nlAddr.toString() + "}"); |
| } |
| } catch (ErrnoException|SocketException e) { |
| logError("Failed to create rtnetlink socket", e); |
| NetworkStackUtils.closeSocketQuietly(fd); |
| return null; |
| } |
| |
| return fd; |
| } |
| |
| @Override |
| protected void handlePacket(byte[] recvbuf, int length) { |
| final long whenMs = SystemClock.elapsedRealtime(); |
| |
| final ByteBuffer byteBuffer = ByteBuffer.wrap(recvbuf, 0, length); |
| byteBuffer.order(ByteOrder.nativeOrder()); |
| |
| parseNetlinkMessageBuffer(byteBuffer, whenMs); |
| } |
| |
| private void parseNetlinkMessageBuffer(ByteBuffer byteBuffer, long whenMs) { |
| while (byteBuffer.remaining() > 0) { |
| final int position = byteBuffer.position(); |
| final NetlinkMessage nlMsg = NetlinkMessage.parse(byteBuffer); |
| if (nlMsg == null || nlMsg.getHeader() == null) { |
| byteBuffer.position(position); |
| mLog.e("unparsable netlink msg: " + hexify(byteBuffer)); |
| break; |
| } |
| |
| final int srcPortId = nlMsg.getHeader().nlmsg_pid; |
| if (srcPortId != 0) { |
| mLog.e("non-kernel source portId: " + Integer.toUnsignedLong(srcPortId)); |
| break; |
| } |
| |
| if (nlMsg instanceof NetlinkErrorMessage) { |
| mLog.e("netlink error: " + nlMsg); |
| continue; |
| } else if (!(nlMsg instanceof RtNetlinkNeighborMessage)) { |
| mLog.i("non-rtnetlink neighbor msg: " + nlMsg); |
| continue; |
| } |
| |
| evaluateRtNetlinkNeighborMessage((RtNetlinkNeighborMessage) nlMsg, whenMs); |
| } |
| } |
| |
| private void evaluateRtNetlinkNeighborMessage( |
| RtNetlinkNeighborMessage neighMsg, long whenMs) { |
| final short msgType = neighMsg.getHeader().nlmsg_type; |
| final StructNdMsg ndMsg = neighMsg.getNdHeader(); |
| if (ndMsg == null) { |
| mLog.e("RtNetlinkNeighborMessage without ND message header!"); |
| return; |
| } |
| |
| final int ifindex = ndMsg.ndm_ifindex; |
| final InetAddress destination = neighMsg.getDestination(); |
| final short nudState = |
| (msgType == RTM_DELNEIGH) |
| ? StructNdMsg.NUD_NONE |
| : ndMsg.ndm_state; |
| |
| final NeighborEvent event = new NeighborEvent( |
| whenMs, msgType, ifindex, destination, nudState, |
| getMacAddress(neighMsg.getLinkLayerAddress())); |
| |
| if (VDBG) { |
| Log.d(TAG, neighMsg.toString()); |
| } |
| if (DBG) { |
| Log.d(TAG, event.toString()); |
| } |
| |
| mConsumer.accept(event); |
| } |
| |
| private static MacAddress getMacAddress(byte[] linkLayerAddress) { |
| if (linkLayerAddress != null) { |
| try { |
| return MacAddress.fromBytes(linkLayerAddress); |
| } catch (IllegalArgumentException e) { |
| Log.e(TAG, "Failed to parse link-layer address: " + hexify(linkLayerAddress)); |
| } |
| } |
| |
| return null; |
| } |
| } |