/*
 * Copyright (C) 2014 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;

import android.content.Context;
import android.net.ConnectivityManager.PacketKeepalive;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.os.Messenger;
import android.util.Log;

import com.android.internal.util.AsyncChannel;
import com.android.internal.util.Protocol;

import java.util.ArrayList;
import java.util.concurrent.atomic.AtomicBoolean;

A Utility class for handling for communicating between bearer-specific
code and ConnectivityService.
A bearer may have more than one NetworkAgent if it can simultaneously
support separate networks (IMS / Internet / MMS Apns on cellular, or
perhaps connections with different SSID or P2P for Wi-Fi).
@hide
/**
 * A Utility class for handling for communicating between bearer-specific
 * code and ConnectivityService.
 *
 * A bearer may have more than one NetworkAgent if it can simultaneously
 * support separate networks (IMS / Internet / MMS Apns on cellular, or
 * perhaps connections with different SSID or P2P for Wi-Fi).
 *
 * @hide
 */
public abstract class NetworkAgent extends Handler {
    // Guaranteed to be valid (not NETID_UNSET), otherwise registerNetworkAgent() would have thrown
    // an exception.
    public final int netId;

    private volatile AsyncChannel mAsyncChannel;
    private final String LOG_TAG;
    private static final boolean DBG = true;
    private static final boolean VDBG = false;
    private final Context mContext;
    private final ArrayList<Message>mPreConnectedQueue = new ArrayList<Message>();
    private volatile long mLastBwRefreshTime = 0;
    private static final long BW_REFRESH_MIN_WIN_MS = 500;
    private boolean mPollLceScheduled = false;
    private AtomicBoolean mPollLcePending = new AtomicBoolean(false);

    private static final int BASE = Protocol.BASE_NETWORK_AGENT;

    
Sent by ConnectivityService to the NetworkAgent to inform it of
suspected connectivity problems on its network.  The NetworkAgent
should take steps to verify and correct connectivity.
/**
     * Sent by ConnectivityService to the NetworkAgent to inform it of
     * suspected connectivity problems on its network.  The NetworkAgent
     * should take steps to verify and correct connectivity.
     */
    public static final int CMD_SUSPECT_BAD = BASE;

    
Sent by the NetworkAgent (note the EVENT vs CMD prefix) to
ConnectivityService to pass the current NetworkInfo (connection state).
Sent when the NetworkInfo changes, mainly due to change of state.
obj = NetworkInfo
/**
     * Sent by the NetworkAgent (note the EVENT vs CMD prefix) to
     * ConnectivityService to pass the current NetworkInfo (connection state).
     * Sent when the NetworkInfo changes, mainly due to change of state.
     * obj = NetworkInfo
     */
    public static final int EVENT_NETWORK_INFO_CHANGED = BASE + 1;

    
Sent by the NetworkAgent to ConnectivityService to pass the current
NetworkCapabilties.
obj = NetworkCapabilities
/**
     * Sent by the NetworkAgent to ConnectivityService to pass the current
     * NetworkCapabilties.
     * obj = NetworkCapabilities
     */
    public static final int EVENT_NETWORK_CAPABILITIES_CHANGED = BASE + 2;

    
Sent by the NetworkAgent to ConnectivityService to pass the current
NetworkProperties.
obj = NetworkProperties
/**
     * Sent by the NetworkAgent to ConnectivityService to pass the current
     * NetworkProperties.
     * obj = NetworkProperties
     */
    public static final int EVENT_NETWORK_PROPERTIES_CHANGED = BASE + 3;

    /* centralize place where base network score, and network score scaling, will be
     * stored, so as we can consistently compare apple and oranges, or wifi, ethernet and LTE
     */
    public static final int WIFI_BASE_SCORE = 60;

    
Sent by the NetworkAgent to ConnectivityService to pass the current
network score.
obj = network score Integer
/**
     * Sent by the NetworkAgent to ConnectivityService to pass the current
     * network score.
     * obj = network score Integer
     */
    public static final int EVENT_NETWORK_SCORE_CHANGED = BASE + 4;

    
Sent by ConnectivityService to the NetworkAgent to inform the agent of the networks status - whether we could use the network or could not, due to either a bad network configuration (no internet link) or captive portal. arg1 = either VALID_NETWORK or INVALID_NETWORK obj = Bundle containing map from REDIRECT_URL_KEY to String representing URL that Internet probe was redirect to, if it was redirected, or mapping to null otherwise. /**
     * Sent by ConnectivityService to the NetworkAgent to inform the agent of the
     * networks status - whether we could use the network or could not, due to
     * either a bad network configuration (no internet link) or captive portal.
     *
     * arg1 = either {@code VALID_NETWORK} or {@code INVALID_NETWORK}
     * obj = Bundle containing map from {@code REDIRECT_URL_KEY} to {@code String}
     *       representing URL that Internet probe was redirect to, if it was redirected,
     *       or mapping to {@code null} otherwise.
     */
    public static final int CMD_REPORT_NETWORK_STATUS = BASE + 7;

    public static final int VALID_NETWORK = 1;
    public static final int INVALID_NETWORK = 2;

    public static String REDIRECT_URL_KEY = "redirect URL";

     
Sent by the NetworkAgent to ConnectivityService to indicate this network was
explicitly selected.  This should be sent before the NetworkInfo is marked
CONNECTED so it can be given special treatment at that time.
obj = boolean indicating whether to use this network even if unvalidated
/**
     * Sent by the NetworkAgent to ConnectivityService to indicate this network was
     * explicitly selected.  This should be sent before the NetworkInfo is marked
     * CONNECTED so it can be given special treatment at that time.
     *
     * obj = boolean indicating whether to use this network even if unvalidated
     */
    public static final int EVENT_SET_EXPLICITLY_SELECTED = BASE + 8;

    
Sent by ConnectivityService to the NetworkAgent to inform the agent of
whether the network should in the future be used even if not validated.
This decision is made by the user, but it is the network transport's
responsibility to remember it.
arg1 = 1 if true, 0 if false
/**
     * Sent by ConnectivityService to the NetworkAgent to inform the agent of
     * whether the network should in the future be used even if not validated.
     * This decision is made by the user, but it is the network transport's
     * responsibility to remember it.
     *
     * arg1 = 1 if true, 0 if false
     */
    public static final int CMD_SAVE_ACCEPT_UNVALIDATED = BASE + 9;

    
Sent by ConnectivityService to the NetworkAgent to inform the agent to pull
the underlying network connection for updated bandwidth information.
/**
     * Sent by ConnectivityService to the NetworkAgent to inform the agent to pull
     * the underlying network connection for updated bandwidth information.
     */
    public static final int CMD_REQUEST_BANDWIDTH_UPDATE = BASE + 10;

    
Sent by ConnectivityService to the NetworkAgent to request that the specified packet be sent
periodically on the given interval.
  arg1 = the slot number of the keepalive to start
  arg2 = interval in seconds
  obj = KeepalivePacketData object describing the data to be sent
Also used internally by ConnectivityService / KeepaliveTracker, with different semantics.
/**
     * Sent by ConnectivityService to the NetworkAgent to request that the specified packet be sent
     * periodically on the given interval.
     *
     *   arg1 = the slot number of the keepalive to start
     *   arg2 = interval in seconds
     *   obj = KeepalivePacketData object describing the data to be sent
     *
     * Also used internally by ConnectivityService / KeepaliveTracker, with different semantics.
     */
    public static final int CMD_START_PACKET_KEEPALIVE = BASE + 11;

    
Requests that the specified keepalive packet be stopped.
arg1 = slot number of the keepalive to stop.
Also used internally by ConnectivityService / KeepaliveTracker, with different semantics.
/**
     * Requests that the specified keepalive packet be stopped.
     *
     * arg1 = slot number of the keepalive to stop.
     *
     * Also used internally by ConnectivityService / KeepaliveTracker, with different semantics.
     */
    public static final int CMD_STOP_PACKET_KEEPALIVE = BASE + 12;

    
Sent by the NetworkAgent to ConnectivityService to provide status on a packet keepalive
request. This may either be the reply to a CMD_START_PACKET_KEEPALIVE, or an asynchronous
error notification.
This is also sent by KeepaliveTracker to the app's ConnectivityManager.PacketKeepalive to
so that the app's PacketKeepaliveCallback methods can be called.
arg1 = slot number of the keepalive
arg2 = error code
/**
     * Sent by the NetworkAgent to ConnectivityService to provide status on a packet keepalive
     * request. This may either be the reply to a CMD_START_PACKET_KEEPALIVE, or an asynchronous
     * error notification.
     *
     * This is also sent by KeepaliveTracker to the app's ConnectivityManager.PacketKeepalive to
     * so that the app's PacketKeepaliveCallback methods can be called.
     *
     * arg1 = slot number of the keepalive
     * arg2 = error code
     */
    public static final int EVENT_PACKET_KEEPALIVE = BASE + 13;

    
Sent by ConnectivityService to inform this network transport of signal strength thresholds
that when crossed should trigger a system wakeup and a NetworkCapabilities update.
  obj = int[] describing signal strength thresholds.
/**
     * Sent by ConnectivityService to inform this network transport of signal strength thresholds
     * that when crossed should trigger a system wakeup and a NetworkCapabilities update.
     *
     *   obj = int[] describing signal strength thresholds.
     */
    public static final int CMD_SET_SIGNAL_STRENGTH_THRESHOLDS = BASE + 14;

    
Sent by ConnectivityService to the NeworkAgent to inform the agent to avoid
automatically reconnecting to this network (e.g. via autojoin).  Happens
when user selects "No" option on the "Stay connected?" dialog box.
/**
     * Sent by ConnectivityService to the NeworkAgent to inform the agent to avoid
     * automatically reconnecting to this network (e.g. via autojoin).  Happens
     * when user selects "No" option on the "Stay connected?" dialog box.
     */
    public static final int CMD_PREVENT_AUTOMATIC_RECONNECT = BASE + 15;

    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);
    }

    public NetworkAgent(Looper looper, Context context, String logTag, NetworkInfo ni,
            NetworkCapabilities nc, LinkProperties lp, int score, NetworkMisc misc) {
        super(looper);
        LOG_TAG = logTag;
        mContext = context;
        if (ni == null || nc == null || lp == null) {
            throw new IllegalArgumentException();
        }

        if (VDBG) log("Registering NetworkAgent");
        ConnectivityManager cm = (ConnectivityManager)mContext.getSystemService(
                Context.CONNECTIVITY_SERVICE);
        netId = cm.registerNetworkAgent(new Messenger(this), new NetworkInfo(ni),
                new LinkProperties(lp), new NetworkCapabilities(nc), score, misc);
    }

    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {
            case AsyncChannel.CMD_CHANNEL_FULL_CONNECTION: {
                if (mAsyncChannel != null) {
                    log("Received new connection while already connected!");
                } else {
                    if (VDBG) log("NetworkAgent fully connected");
                    AsyncChannel ac = new AsyncChannel();
                    ac.connected(null, this, msg.replyTo);
                    ac.replyToMessage(msg, AsyncChannel.CMD_CHANNEL_FULLY_CONNECTED,
                            AsyncChannel.STATUS_SUCCESSFUL);
                    synchronized (mPreConnectedQueue) {
                        mAsyncChannel = ac;
                        for (Message m : mPreConnectedQueue) {
                            ac.sendMessage(m);
                        }
                        mPreConnectedQueue.clear();
                    }
                }
                break;
            }
            case AsyncChannel.CMD_CHANNEL_DISCONNECT: {
                if (VDBG) log("CMD_CHANNEL_DISCONNECT");
                if (mAsyncChannel != null) mAsyncChannel.disconnect();
                break;
            }
            case AsyncChannel.CMD_CHANNEL_DISCONNECTED: {
                if (DBG) log("NetworkAgent channel lost");
                // let the client know CS is done with us.
                unwanted();
                synchronized (mPreConnectedQueue) {
                    mAsyncChannel = null;
                }
                break;
            }
            case CMD_SUSPECT_BAD: {
                log("Unhandled Message " + msg);
                break;
            }
            case CMD_REQUEST_BANDWIDTH_UPDATE: {
                long currentTimeMs = System.currentTimeMillis();
                if (VDBG) {
                    log("CMD_REQUEST_BANDWIDTH_UPDATE request received.");
                }
                if (currentTimeMs >= (mLastBwRefreshTime + BW_REFRESH_MIN_WIN_MS)) {
                    mPollLceScheduled = false;
                    if (mPollLcePending.getAndSet(true) == false) {
                        pollLceData();
                    }
                } else {
                    // deliver the request at a later time rather than discard it completely.
                    if (!mPollLceScheduled) {
                        long waitTime = mLastBwRefreshTime + BW_REFRESH_MIN_WIN_MS -
                                currentTimeMs + 1;
                        mPollLceScheduled = sendEmptyMessageDelayed(
                                CMD_REQUEST_BANDWIDTH_UPDATE, waitTime);
                    }
                }
                break;
            }
            case CMD_REPORT_NETWORK_STATUS: {
                String redirectUrl = ((Bundle)msg.obj).getString(REDIRECT_URL_KEY);
                if (VDBG) {
                    log("CMD_REPORT_NETWORK_STATUS(" +
                            (msg.arg1 == VALID_NETWORK ? "VALID, " : "INVALID, ") + redirectUrl);
                }
                networkStatus(msg.arg1, redirectUrl);
                break;
            }
            case CMD_SAVE_ACCEPT_UNVALIDATED: {
                saveAcceptUnvalidated(msg.arg1 != 0);
                break;
            }
            case CMD_START_PACKET_KEEPALIVE: {
                startPacketKeepalive(msg);
                break;
            }
            case CMD_STOP_PACKET_KEEPALIVE: {
                stopPacketKeepalive(msg);
                break;
            }

            case CMD_SET_SIGNAL_STRENGTH_THRESHOLDS: {
                ArrayList<Integer> thresholds =
                        ((Bundle) msg.obj).getIntegerArrayList("thresholds");
                // TODO: Change signal strength thresholds API to use an ArrayList<Integer>
                // rather than convert to int[].
                int[] intThresholds = new int[(thresholds != null) ? thresholds.size() : 0];
                for (int i = 0; i < intThresholds.length; i++) {
                    intThresholds[i] = thresholds.get(i);
                }
                setSignalStrengthThresholds(intThresholds);
                break;
            }
            case CMD_PREVENT_AUTOMATIC_RECONNECT: {
                preventAutomaticReconnect();
                break;
            }
        }
    }

    private void queueOrSendMessage(int what, Object obj) {
        queueOrSendMessage(what, 0, 0, obj);
    }

    private void queueOrSendMessage(int what, int arg1, int arg2) {
        queueOrSendMessage(what, arg1, arg2, null);
    }

    private void queueOrSendMessage(int what, int arg1, int arg2, Object obj) {
        Message msg = Message.obtain();
        msg.what = what;
        msg.arg1 = arg1;
        msg.arg2 = arg2;
        msg.obj = obj;
        queueOrSendMessage(msg);
    }

    private void queueOrSendMessage(Message msg) {
        synchronized (mPreConnectedQueue) {
            if (mAsyncChannel != null) {
                mAsyncChannel.sendMessage(msg);
            } else {
                mPreConnectedQueue.add(msg);
            }
        }
    }

    
Called by the bearer code when it has new LinkProperties data.
/**
     * Called by the bearer code when it has new LinkProperties data.
     */
    public void sendLinkProperties(LinkProperties linkProperties) {
        queueOrSendMessage(EVENT_NETWORK_PROPERTIES_CHANGED, new LinkProperties(linkProperties));
    }

    
Called by the bearer code when it has new NetworkInfo data.
/**
     * Called by the bearer code when it has new NetworkInfo data.
     */
    public void sendNetworkInfo(NetworkInfo networkInfo) {
        queueOrSendMessage(EVENT_NETWORK_INFO_CHANGED, new NetworkInfo(networkInfo));
    }

    
Called by the bearer code when it has new NetworkCapabilities data.
/**
     * Called by the bearer code when it has new NetworkCapabilities data.
     */
    public void sendNetworkCapabilities(NetworkCapabilities networkCapabilities) {
        mPollLcePending.set(false);
        mLastBwRefreshTime = System.currentTimeMillis();
        queueOrSendMessage(EVENT_NETWORK_CAPABILITIES_CHANGED,
                new NetworkCapabilities(networkCapabilities));
    }

    
Called by the bearer code when it has a new score for this network.
/**
     * Called by the bearer code when it has a new score for this network.
     */
    public void sendNetworkScore(int score) {
        if (score < 0) {
            throw new IllegalArgumentException("Score must be >= 0");
        }
        queueOrSendMessage(EVENT_NETWORK_SCORE_CHANGED, new Integer(score));
    }

    
Called by the bearer to indicate this network was manually selected by the user. This should be called before the NetworkInfo is marked CONNECTED so that this Network can be given special treatment at that time. If acceptUnvalidated is true, then the system will switch to this network. If it is false and the network cannot be validated, the system will ask the user whether to switch to this network. If the user confirms and selects "don't ask again", then the system will call saveAcceptUnvalidated to persist the user's choice. Thus, if the transport ever calls this method with acceptUnvalidated set to false, it must also implement saveAcceptUnvalidated to respect the user's choice. /**
     * Called by the bearer to indicate this network was manually selected by the user.
     * This should be called before the NetworkInfo is marked CONNECTED so that this
     * Network can be given special treatment at that time. If {@code acceptUnvalidated} is
     * {@code true}, then the system will switch to this network. If it is {@code false} and the
     * network cannot be validated, the system will ask the user whether to switch to this network.
     * If the user confirms and selects "don't ask again", then the system will call
     * {@link #saveAcceptUnvalidated} to persist the user's choice. Thus, if the transport ever
     * calls this method with {@code acceptUnvalidated} set to {@code false}, it must also implement
     * {@link #saveAcceptUnvalidated} to respect the user's choice.
     */
    public void explicitlySelected(boolean acceptUnvalidated) {
        queueOrSendMessage(EVENT_SET_EXPLICITLY_SELECTED, acceptUnvalidated);
    }

    
Called when ConnectivityService has indicated they no longer want this network.
The parent factory should (previously) have received indication of the change
as well, either canceling NetworkRequests or altering their score such that this
network won't be immediately requested again.
/**
     * Called when ConnectivityService has indicated they no longer want this network.
     * The parent factory should (previously) have received indication of the change
     * as well, either canceling NetworkRequests or altering their score such that this
     * network won't be immediately requested again.
     */
    abstract protected void unwanted();

    
Called when ConnectivityService request a bandwidth update. The parent factory
shall try to overwrite this method and produce a bandwidth update if capable.
/**
     * Called when ConnectivityService request a bandwidth update. The parent factory
     * shall try to overwrite this method and produce a bandwidth update if capable.
     */
    protected void pollLceData() {
    }

    
Called when the system determines the usefulness of this network. Networks claiming internet connectivity will have their internet connectivity verified. Currently there are two possible values: VALID_NETWORK if the system is happy with the connection, INVALID_NETWORK if the system is not happy. TODO - add indications of captive portal-ness and related success/failure, ie, CAPTIVE_SUCCESS_NETWORK, CAPTIVE_NETWORK for successful login and detection This may be called multiple times as the network status changes and may generate false negatives if we lose ip connectivity before the link is torn down. 
Params:
status – one of VALID_NETWORK or INVALID_NETWORK.
redirectUrl – If the Internet probe was redirected, this is the destination it was redirected to, otherwise null./**
     * Called when the system determines the usefulness of this network.
     *
     * Networks claiming internet connectivity will have their internet
     * connectivity verified.
     *
     * Currently there are two possible values:
     * {@code VALID_NETWORK} if the system is happy with the connection,
     * {@code INVALID_NETWORK} if the system is not happy.
     * TODO - add indications of captive portal-ness and related success/failure,
     * ie, CAPTIVE_SUCCESS_NETWORK, CAPTIVE_NETWORK for successful login and detection
     *
     * This may be called multiple times as the network status changes and may
     * generate false negatives if we lose ip connectivity before the link is torn down.
     *
     * @param status one of {@code VALID_NETWORK} or {@code INVALID_NETWORK}.
     * @param redirectUrl If the Internet probe was redirected, this is the destination it was
     *         redirected to, otherwise {@code null}.
     */
    protected void networkStatus(int status, String redirectUrl) {
    }

    
Called when the user asks to remember the choice to use this network even if unvalidated. The transport is responsible for remembering the choice, and the next time the user connects to the network, should explicitlySelected with acceptUnvalidated set to true. This method will only be called if explicitlySelected was called with acceptUnvalidated set to false. /**
     * Called when the user asks to remember the choice to use this network even if unvalidated.
     * The transport is responsible for remembering the choice, and the next time the user connects
     * to the network, should explicitlySelected with {@code acceptUnvalidated} set to {@code true}.
     * This method will only be called if {@link #explicitlySelected} was called with
     * {@code acceptUnvalidated} set to {@code false}.
     */
    protected void saveAcceptUnvalidated(boolean accept) {
    }

    
Requests that the network hardware send the specified packet at the specified interval.
/**
     * Requests that the network hardware send the specified packet at the specified interval.
     */
    protected void startPacketKeepalive(Message msg) {
        onPacketKeepaliveEvent(msg.arg1, PacketKeepalive.ERROR_HARDWARE_UNSUPPORTED);
    }

    
Requests that the network hardware send the specified packet at the specified interval.
/**
     * Requests that the network hardware send the specified packet at the specified interval.
     */
    protected void stopPacketKeepalive(Message msg) {
        onPacketKeepaliveEvent(msg.arg1, PacketKeepalive.ERROR_HARDWARE_UNSUPPORTED);
    }

    
Called by the network when a packet keepalive event occurs.
/**
     * Called by the network when a packet keepalive event occurs.
     */
    public void onPacketKeepaliveEvent(int slot, int reason) {
        queueOrSendMessage(EVENT_PACKET_KEEPALIVE, slot, reason);
    }

    
Called by ConnectivityService to inform this network transport of signal strength thresholds
that when crossed should trigger a system wakeup and a NetworkCapabilities update.
/**
     * Called by ConnectivityService to inform this network transport of signal strength thresholds
     * that when crossed should trigger a system wakeup and a NetworkCapabilities update.
     */
    protected void setSignalStrengthThresholds(int[] thresholds) {
    }

    
Called when the user asks to not stay connected to this network because it was found to not provide Internet access. Usually followed by call to unwanted. The transport is responsible for making sure the device does not automatically reconnect to the same network after the unwanted call. /**
     * Called when the user asks to not stay connected to this network because it was found to not
     * provide Internet access.  Usually followed by call to {@code unwanted}.  The transport is
     * responsible for making sure the device does not automatically reconnect to the same network
     * after the {@code unwanted} call.
     */
    protected void preventAutomaticReconnect() {
    }

    protected void log(String s) {
        Log.d(LOG_TAG, "NetworkAgent: " + s);
    }
}