wifi/aware/WifiAwareDataPathStateManager.java

/*
 * Copyright (C) 2016 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 com.android.server.wifi.aware;

import android.content.Context;
import android.hardware.wifi.V1_0.NanDataPathChannelCfg;
import android.net.ConnectivityManager;
import android.net.IpPrefix;
import android.net.LinkAddress;
import android.net.LinkProperties;
import android.net.MatchAllNetworkSpecifier;
import android.net.NetworkAgent;
import android.net.NetworkCapabilities;
import android.net.NetworkFactory;
import android.net.NetworkInfo;
import android.net.NetworkRequest;
import android.net.NetworkSpecifier;
import android.net.RouteInfo;
import android.net.StringNetworkSpecifier;
import android.net.wifi.aware.WifiAwareManager;
import android.os.IBinder;
import android.os.INetworkManagementService;
import android.os.Looper;
import android.os.ServiceManager;
import android.text.TextUtils;
import android.util.ArrayMap;
import android.util.Base64;
import android.util.Log;

import com.android.internal.annotations.VisibleForTesting;

import libcore.util.HexEncoding;

import org.json.JSONException;
import org.json.JSONObject;

import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

/**
 * Manages Aware data-path lifetime: interface creation/deletion, data-path setup and tear-down.
 * The Aware network configuration is:
 * - transport = TRANSPORT_WIFI_AWARE
 * - capabilities = NET_CAPABILITY_NOT_VPN
 * - network specifier generated by DiscoverySession.createNetworkSpecifier(...) or
 *   WifiAwareManager.createNetworkSpecifier(...).
 *   The network specifier is encoded as a JSON string with the key combos described in
 *   {@link WifiAwareManager} as {@code NETWORK_SPECIFIER_TYPE_*}.
 */
public class WifiAwareDataPathStateManager {
    private static final String TAG = "WifiAwareDataPathStMgr";

    private static final boolean DBG = false;
    private static final boolean VDBG = false; // STOPSHIP if true

    private static final String AWARE_INTERFACE_PREFIX = "aware_data";
    private static final String NETWORK_TAG = "WIFI_AWARE_FACTORY";
    private static final String AGENT_TAG_PREFIX = "WIFI_AWARE_AGENT_";
    private static final int NETWORK_FACTORY_SCORE_AVAIL = 1;
    private static final int NETWORK_FACTORY_BANDWIDTH_AVAIL = 1;
    private static final int NETWORK_FACTORY_SIGNAL_STRENGTH_AVAIL = 1;

    private final WifiAwareStateManager mMgr;
    private final NetworkInterfaceWrapper mNiWrapper = new NetworkInterfaceWrapper();
    private final NetworkCapabilities mNetworkCapabilitiesFilter = new NetworkCapabilities();
    private final Set<String> mInterfaces = new HashSet<>();
    private final Map<String, AwareNetworkRequestInformation> mNetworkRequestsCache =
            new ArrayMap<>();
    private Context mContext;
    private Looper mLooper;
    private WifiAwareNetworkFactory mNetworkFactory;
    private INetworkManagementService mNwService;

    public WifiAwareDataPathStateManager(WifiAwareStateManager mgr) {
        mMgr = mgr;
    }

    /**
     * Initialize the Aware data-path state manager. Specifically register the network factory with
     * connectivity service.
     */
    public void start(Context context, Looper looper) {
        if (VDBG) Log.v(TAG, "start");

        mContext = context;
        mLooper = looper;

        mNetworkCapabilitiesFilter.clearAll();
        mNetworkCapabilitiesFilter.addTransportType(NetworkCapabilities.TRANSPORT_WIFI_AWARE);
        mNetworkCapabilitiesFilter
                .addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN)
                .addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_METERED)
                .addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED)
                .addCapability(NetworkCapabilities.NET_CAPABILITY_TRUSTED);
        mNetworkCapabilitiesFilter.setNetworkSpecifier(new MatchAllNetworkSpecifier());
        mNetworkCapabilitiesFilter.setLinkUpstreamBandwidthKbps(NETWORK_FACTORY_BANDWIDTH_AVAIL);
        mNetworkCapabilitiesFilter.setLinkDownstreamBandwidthKbps(NETWORK_FACTORY_BANDWIDTH_AVAIL);
        mNetworkCapabilitiesFilter.setSignalStrength(NETWORK_FACTORY_SIGNAL_STRENGTH_AVAIL);

        mNetworkFactory = new WifiAwareNetworkFactory(looper, context, mNetworkCapabilitiesFilter);
        mNetworkFactory.setScoreFilter(NETWORK_FACTORY_SCORE_AVAIL);
        mNetworkFactory.register();

        IBinder b = ServiceManager.getService(Context.NETWORKMANAGEMENT_SERVICE);
        mNwService = INetworkManagementService.Stub.asInterface(b);
    }

    private Map.Entry<String, AwareNetworkRequestInformation> getNetworkRequestByNdpId(int ndpId) {
        for (Map.Entry<String, AwareNetworkRequestInformation> entry : mNetworkRequestsCache
                .entrySet()) {
            if (entry.getValue().ndpId == ndpId) {
                return entry;
            }
        }

        return null;
    }

    /**
     * Create all Aware data-path interfaces which are possible on the device - based on the
     * capabilities of the firmware.
     */
    public void createAllInterfaces() {
        if (VDBG) Log.v(TAG, "createAllInterfaces");

        if (mMgr.getCapabilities() == null) {
            Log.e(TAG, "createAllInterfaces: capabilities aren't initialized yet!");
            return;
        }

        for (int i = 0; i < mMgr.getCapabilities().maxNdiInterfaces; ++i) {
            String name = AWARE_INTERFACE_PREFIX + i;
            if (mInterfaces.contains(name)) {
                Log.e(TAG, "createAllInterfaces(): interface already up, " + name
                        + ", possibly failed to delete - deleting/creating again to be safe");
                mMgr.deleteDataPathInterface(name);

                // critical to remove so that don't get infinite loop if the delete fails again
                mInterfaces.remove(name);
            }

            mMgr.createDataPathInterface(name);
        }
    }

    /**
     * Delete all Aware data-path interfaces which are currently up.
     */
    public void deleteAllInterfaces() {
        if (VDBG) Log.v(TAG, "deleteAllInterfaces");

        for (String name : mInterfaces) {
            mMgr.deleteDataPathInterface(name);
        }
    }

    /**
     * Called when firmware indicates the an interface was created.
     */
    public void onInterfaceCreated(String interfaceName) {
        if (VDBG) Log.v(TAG, "onInterfaceCreated: interfaceName=" + interfaceName);

        if (mInterfaces.contains(interfaceName)) {
            Log.w(TAG, "onInterfaceCreated: already contains interface -- " + interfaceName);
        }

        mInterfaces.add(interfaceName);
    }

    /**
     * Called when firmware indicates the an interface was deleted.
     */
    public void onInterfaceDeleted(String interfaceName) {
        if (VDBG) Log.v(TAG, "onInterfaceDeleted: interfaceName=" + interfaceName);

        if (!mInterfaces.contains(interfaceName)) {
            Log.w(TAG, "onInterfaceDeleted: interface not on list -- " + interfaceName);
        }

        mInterfaces.remove(interfaceName);
    }

    /**
     * Response to initiating data-path request. Indicates that request is successful (not
     * complete!) and is now in progress.
     *
     * @param networkSpecifier The network specifier provided as part of the initiate request.
     * @param ndpId            The ID assigned to the data-path.
     */
    public void onDataPathInitiateSuccess(String networkSpecifier, int ndpId) {
        if (VDBG) {
            Log.v(TAG,
                    "onDataPathInitiateSuccess: networkSpecifier=" + networkSpecifier + ", ndpId="
                            + ndpId);
        }

        AwareNetworkRequestInformation nnri = mNetworkRequestsCache.get(networkSpecifier);
        if (nnri == null) {
            Log.w(TAG, "onDataPathInitiateSuccess: network request not found for networkSpecifier="
                    + networkSpecifier);
            mMgr.endDataPath(ndpId);
            return;
        }

        if (nnri.state
                != AwareNetworkRequestInformation.STATE_INITIATOR_WAIT_FOR_REQUEST_RESPONSE) {
            Log.w(TAG, "onDataPathInitiateSuccess: network request in incorrect state: state="
                    + nnri.state);
            mNetworkRequestsCache.remove(networkSpecifier);
            mMgr.endDataPath(ndpId);
            return;
        }

        nnri.state = AwareNetworkRequestInformation.STATE_INITIATOR_WAIT_FOR_CONFIRM;
        nnri.ndpId = ndpId;
    }

    /**
     * Response to an attempt to set up a data-path (on the initiator side).
     *
     * @param networkSpecifier The network specifier provided as part of the initiate request.
     * @param reason           Failure reason.
     */
    public void onDataPathInitiateFail(String networkSpecifier, int reason) {
        if (VDBG) {
            Log.v(TAG,
                    "onDataPathInitiateFail: networkSpecifier=" + networkSpecifier + ", reason="
                            + reason);
        }

        AwareNetworkRequestInformation nnri = mNetworkRequestsCache.remove(networkSpecifier);
        if (nnri == null) {
            Log.w(TAG, "onDataPathInitiateFail: network request not found for networkSpecifier="
                    + networkSpecifier);
            return;
        }

        if (nnri.state
                != AwareNetworkRequestInformation.STATE_INITIATOR_WAIT_FOR_REQUEST_RESPONSE) {
            Log.w(TAG, "onDataPathInitiateFail: network request in incorrect state: state="
                    + nnri.state);
        }

        mNetworkRequestsCache.remove(networkSpecifier);
    }


    /**
     * Notification (unsolicited/asynchronous) that a peer has requested to set up a data-path
     * connection with us.
     *
     * @param pubSubId      The ID of the discovery session context for the data-path - or 0 if not
     *                      related to a discovery session.
     * @param mac           The discovery MAC address of the peer.
     * @param ndpId         The locally assigned ID for the data-path.
     * @return The network specifier of the data-path (or null if none/error)
     */
    public String onDataPathRequest(int pubSubId, byte[] mac, int ndpId) {
        if (VDBG) {
            Log.v(TAG,
                    "onDataPathRequest: pubSubId=" + pubSubId + ", mac=" + String.valueOf(
                            HexEncoding.encode(mac)) + ", ndpId=" + ndpId);
        }

        String networkSpecifier = null;
        AwareNetworkRequestInformation nnri = null;
        for (Map.Entry<String, AwareNetworkRequestInformation> entry : mNetworkRequestsCache
                .entrySet()) {
            /*
             * Checking that the incoming request (from the Initiator) matches the request
             * we (the Responder) already have set up. The rules are:
             * - The discovery session (pub/sub ID) must match.
             * - The peer MAC address (if specified - i.e. non-null) must match. A null peer MAC ==
             *   accept (otherwise matching) requests from any peer MAC.
             */
            if (entry.getValue().pubSubId != 0 && entry.getValue().pubSubId != pubSubId) {
                continue;
            }

            if (entry.getValue().peerDiscoveryMac != null && !Arrays.equals(
                    entry.getValue().peerDiscoveryMac, mac)) {
                continue;
            }

            networkSpecifier = entry.getKey();
            nnri = entry.getValue();
            break;
        }

        if (nnri == null) {
            Log.w(TAG, "onDataPathRequest: can't find a request with specified pubSubId=" + pubSubId
                    + ", mac=" + String.valueOf(HexEncoding.encode(mac)));
            if (DBG) {
                Log.d(TAG, "onDataPathRequest: network request cache = " + mNetworkRequestsCache);
            }
            mMgr.respondToDataPathRequest(false, ndpId, "", null, null);
            return null;
        }

        if (nnri.state != AwareNetworkRequestInformation.STATE_RESPONDER_WAIT_FOR_REQUEST) {
            Log.w(TAG, "onDataPathRequest: request " + networkSpecifier + " is incorrect state="
                    + nnri.state);
            mMgr.respondToDataPathRequest(false, ndpId, "", null, null);
            mNetworkRequestsCache.remove(networkSpecifier);
            return null;
        }

        nnri.state = AwareNetworkRequestInformation.STATE_RESPONDER_WAIT_FOR_RESPOND_RESPONSE;
        nnri.ndpId = ndpId;
        nnri.interfaceName = selectInterfaceForRequest(nnri);
        mMgr.respondToDataPathRequest(true, ndpId, nnri.interfaceName, nnri.pmk, nnri.passphrase);

        return networkSpecifier;
    }

    /**
     * Called on the RESPONDER when the response to data-path request has been completed.
     *
     * @param ndpId The ID of the data-path (NDP)
     * @param success Whether or not the 'RespondToDataPathRequest' operation was a success.
     */
    public void onRespondToDataPathRequest(int ndpId, boolean success) {
        if (VDBG) {
            Log.v(TAG, "onRespondToDataPathRequest: ndpId=" + ndpId + ", success=" + success);
        }

        String networkSpecifier = null;
        AwareNetworkRequestInformation nnri = null;
        for (Map.Entry<String, AwareNetworkRequestInformation> entry : mNetworkRequestsCache
                .entrySet()) {
            if (entry.getValue().ndpId == ndpId) {
                networkSpecifier = entry.getKey();
                nnri = entry.getValue();
                break;
            }
        }

        if (nnri == null) {
            Log.w(TAG, "onRespondToDataPathRequest: can't find a request with specified ndpId="
                    + ndpId);
            if (DBG) {
                Log.d(TAG, "onRespondToDataPathRequest: network request cache = "
                        + mNetworkRequestsCache);
            }
            return;
        }

        if (!success) {
            Log.w(TAG, "onRespondToDataPathRequest: request " + networkSpecifier
                    + " failed responding");
            mMgr.endDataPath(ndpId);
            mNetworkRequestsCache.remove(networkSpecifier);
            return;
        }

        if (nnri.state
                != AwareNetworkRequestInformation.STATE_RESPONDER_WAIT_FOR_RESPOND_RESPONSE) {
            Log.w(TAG, "onRespondToDataPathRequest: request " + networkSpecifier
                    + " is incorrect state=" + nnri.state);
            mMgr.endDataPath(ndpId);
            mNetworkRequestsCache.remove(networkSpecifier);
            return;
        }

        nnri.state = AwareNetworkRequestInformation.STATE_RESPONDER_WAIT_FOR_CONFIRM;
    }

    /**
     * Notification (unsolicited/asynchronous) that the data-path (which we've been setting up)
     * is possibly (if {@code accept} is {@code true}) ready for use from the firmware's
     * perspective - now can do L3 configuration.
     *
     * @param ndpId         Id of the data-path
     * @param mac           The MAC address of the peer's data-path (not discovery interface). Only
     *                      valid
     *                      if {@code accept} is {@code true}.
     * @param accept        Indicates whether the data-path setup has succeeded (been accepted) or
     *                      failed (been rejected).
     * @param reason        If {@code accept} is {@code false} provides a reason code for the
     *                      rejection/failure.
     * @param message       The message provided by the peer as part of the data-path setup
     *                      process.
     * @return The network specifier of the data-path or a null if none/error.
     */
    public String onDataPathConfirm(int ndpId, byte[] mac, boolean accept, int reason,
            byte[] message) {
        if (VDBG) {
            Log.v(TAG, "onDataPathConfirm: ndpId=" + ndpId + ", mac=" + String.valueOf(
                    HexEncoding.encode(mac)) + ", accept=" + accept + ", reason=" + reason);
        }

        Map.Entry<String, AwareNetworkRequestInformation> nnriE = getNetworkRequestByNdpId(ndpId);
        if (nnriE == null) {
            Log.w(TAG, "onDataPathConfirm: network request not found for ndpId=" + ndpId);
            if (accept) {
                mMgr.endDataPath(ndpId);
            }
            return null;
        }

        String networkSpecifier = nnriE.getKey();
        AwareNetworkRequestInformation nnri = nnriE.getValue();

        // validate state
        if (nnri.role == WifiAwareManager.WIFI_AWARE_DATA_PATH_ROLE_INITIATOR
                && nnri.state != AwareNetworkRequestInformation.STATE_INITIATOR_WAIT_FOR_CONFIRM) {
            Log.w(TAG, "onDataPathConfirm: INITIATOR in invalid state=" + nnri.state);
            mNetworkRequestsCache.remove(networkSpecifier);
            if (accept) {
                mMgr.endDataPath(ndpId);
            }
            return networkSpecifier;
        }
        if (nnri.role == WifiAwareManager.WIFI_AWARE_DATA_PATH_ROLE_RESPONDER
                && nnri.state != AwareNetworkRequestInformation.STATE_RESPONDER_WAIT_FOR_CONFIRM) {
            Log.w(TAG, "onDataPathConfirm: RESPONDER in invalid state=" + nnri.state);
            mNetworkRequestsCache.remove(networkSpecifier);
            if (accept) {
                mMgr.endDataPath(ndpId);
            }
            return networkSpecifier;
        }

        if (accept) {
            nnri.state = (nnri.role == WifiAwareManager.WIFI_AWARE_DATA_PATH_ROLE_INITIATOR)
                    ? AwareNetworkRequestInformation.STATE_INITIATOR_CONFIRMED
                    : AwareNetworkRequestInformation.STATE_RESPONDER_CONFIRMED;
            nnri.peerDataMac = mac;

            NetworkInfo networkInfo = new NetworkInfo(ConnectivityManager.TYPE_WIFI_P2P, 0,
                    NETWORK_TAG, "");
            NetworkCapabilities networkCapabilities = new NetworkCapabilities(
                    mNetworkCapabilitiesFilter);
            LinkProperties linkProperties = new LinkProperties();

            try {
                mNwService.setInterfaceUp(nnri.interfaceName);
                mNwService.enableIpv6(nnri.interfaceName);
            } catch (Exception e) { // NwService throws runtime exceptions for errors
                Log.e(TAG, "onDataPathConfirm: ACCEPT nnri=" + nnri + ": can't configure network - "
                        + e);
                mMgr.endDataPath(ndpId);
                return networkSpecifier;
            }

            if (!mNiWrapper.configureAgentProperties(nnri, networkSpecifier, ndpId, networkInfo,
                    networkCapabilities, linkProperties)) {
                return networkSpecifier;
            }

            nnri.networkAgent = new WifiAwareNetworkAgent(mLooper, mContext,
                    AGENT_TAG_PREFIX + nnri.ndpId,
                    new NetworkInfo(ConnectivityManager.TYPE_WIFI_P2P, 0, NETWORK_TAG, ""),
                    networkCapabilities, linkProperties, NETWORK_FACTORY_SCORE_AVAIL,
                    networkSpecifier, ndpId);
            nnri.networkAgent.sendNetworkInfo(networkInfo);
        } else {
            if (DBG) {
                Log.d(TAG, "onDataPathConfirm: data-path for networkSpecifier=" + networkSpecifier
                        + " rejected - reason=" + reason);
            }
            mNetworkRequestsCache.remove(networkSpecifier);
        }

        return networkSpecifier;
    }

    /**
     * Notification (unsolicited/asynchronous) from the firmware that the specified data-path has
     * been terminated.
     *
     * @param ndpId The ID of the terminated data-path.
     */
    public void onDataPathEnd(int ndpId) {
        if (VDBG) Log.v(TAG, "onDataPathEnd: ndpId=" + ndpId);

        Map.Entry<String, AwareNetworkRequestInformation> nnriE = getNetworkRequestByNdpId(ndpId);
        if (nnriE == null) {
            if (DBG) {
                Log.d(TAG, "onDataPathEnd: network request not found for ndpId=" + ndpId);
            }
            return;
        }

        tearDownInterface(nnriE.getValue());
        mNetworkRequestsCache.remove(nnriE.getKey());
    }

    /**
     * Called whenever Aware comes down. Clean up all pending and up network requeests and agents.
     */
    public void onAwareDownCleanupDataPaths() {
        if (VDBG) Log.v(TAG, "onAwareDownCleanupDataPaths");

        for (AwareNetworkRequestInformation nnri : mNetworkRequestsCache.values()) {
            tearDownInterface(nnri);
        }
        mNetworkRequestsCache.clear();
    }

    /**
     * Called when timed-out waiting for confirmation of the data-path setup (i.e.
     * onDataPathConfirm). Started on the initiator when executing the request for the data-path
     * and on the responder when received a request for data-path (in both cases only on success
     * - i.e. when we're proceeding with data-path setup).
     */
    public void handleDataPathTimeout(String networkSpecifier) {
        if (VDBG) Log.v(TAG, "handleDataPathTimeout: networkSpecifier=" + networkSpecifier);

        AwareNetworkRequestInformation nnri = mNetworkRequestsCache.remove(networkSpecifier);
        if (nnri == null) {
            if (DBG) {
                Log.d(TAG,
                        "handleDataPathTimeout: network request not found for networkSpecifier="
                                + networkSpecifier);
            }
            return;
        }

        mMgr.endDataPath(nnri.ndpId);
    }

    private class WifiAwareNetworkFactory extends NetworkFactory {
        WifiAwareNetworkFactory(Looper looper, Context context, NetworkCapabilities filter) {
            super(looper, context, NETWORK_TAG, filter);
        }

        @Override
        public boolean acceptRequest(NetworkRequest request, int score) {
            if (VDBG) {
                Log.v(TAG, "WifiAwareNetworkFactory.acceptRequest: request=" + request + ", score="
                        + score);
            }

            if (!mMgr.isUsageEnabled()) {
                if (VDBG) {
                    Log.v(TAG, "WifiAwareNetworkFactory.acceptRequest: request=" + request
                            + " -- Aware disabled");
                }
                return false;
            }

            if (mInterfaces.isEmpty()) {
                Log.w(TAG, "WifiAwareNetworkFactory.acceptRequest: request=" + request
                        + " -- No Aware interfaces are up");
                return false;
            }

            NetworkSpecifier networkSpecifierObj =
                    request.networkCapabilities.getNetworkSpecifier();
            if (networkSpecifierObj == null
                    || !(networkSpecifierObj instanceof StringNetworkSpecifier)
                    || TextUtils.isEmpty(
                    ((StringNetworkSpecifier) networkSpecifierObj).specifier)) {
                Log.w(TAG, "WifiAwareNetworkFactory.acceptRequest: request=" + request
                        + " - null, empty, or not a StringNetworkSpecifier");
                return false;
            }
            String networkSpecifier = ((StringNetworkSpecifier) networkSpecifierObj).specifier;

            // look up specifier - are we being called again?
            AwareNetworkRequestInformation nnri = mNetworkRequestsCache.get(networkSpecifier);
            if (nnri != null) {
                if (DBG) {
                    Log.d(TAG, "WifiAwareNetworkFactory.acceptRequest: request=" + request
                            + " - already in cache!?");
                }

                // seems to happen after a network agent is created - trying to rematch all
                // requests again!?
                return true;
            }

            // parse network specifier (JSON) & cache
            // TODO: validate that the client ID actually comes from the correct process and is
            // not faked?
            nnri = AwareNetworkRequestInformation.parseNetworkSpecifier(networkSpecifier, mMgr);
            if (nnri == null) {
                Log.e(TAG, "WifiAwareNetworkFactory.acceptRequest: request=" + request
                        + " - can't parse network specifier");
                return false;
            }
            mNetworkRequestsCache.put(networkSpecifier, nnri);

            return true;
        }

        @Override
        protected void needNetworkFor(NetworkRequest networkRequest, int score) {
            if (VDBG) {
                Log.v(TAG, "WifiAwareNetworkFactory.needNetworkFor: networkRequest="
                        + networkRequest + ", score=" + score);
            }

            NetworkSpecifier networkSpecifierObj =
                    networkRequest.networkCapabilities.getNetworkSpecifier();
            String networkSpecifier = "";
            if (networkSpecifierObj != null
                    && networkSpecifierObj instanceof StringNetworkSpecifier) {
                networkSpecifier = ((StringNetworkSpecifier) networkSpecifierObj).specifier;
            }
            AwareNetworkRequestInformation nnri = mNetworkRequestsCache.get(networkSpecifier);
            if (nnri == null) {
                Log.e(TAG, "WifiAwareNetworkFactory.needNetworkFor: networkRequest="
                        + networkRequest + " not in cache!?");
                return;
            }

            if (nnri.role == WifiAwareManager.WIFI_AWARE_DATA_PATH_ROLE_INITIATOR) {
                if (nnri.state != AwareNetworkRequestInformation.STATE_INITIATOR_IDLE) {
                    if (DBG) {
                        Log.d(TAG, "WifiAwareNetworkFactory.needNetworkFor: networkRequest="
                                + networkRequest + " - already in progress");
                        // TODO: understand how/when can be called again/while in progress (seems
                        // to be related to score re-calculation after a network agent is created)
                    }
                    return;
                }

                nnri.interfaceName = selectInterfaceForRequest(nnri);
                mMgr.initiateDataPathSetup(networkSpecifier, nnri.peerId,
                        NanDataPathChannelCfg.REQUEST_CHANNEL_SETUP, selectChannelForRequest(nnri),
                        nnri.peerDiscoveryMac, nnri.interfaceName, nnri.pmk, nnri.passphrase);
                nnri.state =
                        AwareNetworkRequestInformation.STATE_INITIATOR_WAIT_FOR_REQUEST_RESPONSE;
            } else {
                if (nnri.state != AwareNetworkRequestInformation.STATE_RESPONDER_IDLE) {
                    if (DBG) {
                        Log.d(TAG, "WifiAwareNetworkFactory.needNetworkFor: networkRequest="
                                + networkRequest + " - already in progress");
                        // TODO: understand how/when can be called again/while in progress (seems
                        // to be related to score re-calculation after a network agent is created)
                    }
                    return;
                }

                nnri.state = AwareNetworkRequestInformation.STATE_RESPONDER_WAIT_FOR_REQUEST;
            }
        }

        @Override
        protected void releaseNetworkFor(NetworkRequest networkRequest) {
            if (VDBG) {
                Log.v(TAG, "WifiAwareNetworkFactory.releaseNetworkFor: networkRequest="
                        + networkRequest);
            }

            NetworkSpecifier networkSpecifierObj =
                    networkRequest.networkCapabilities.getNetworkSpecifier();
            String networkSpecifier = "";
            if (networkSpecifierObj != null
                    && networkSpecifierObj instanceof StringNetworkSpecifier) {
                networkSpecifier = ((StringNetworkSpecifier) networkSpecifierObj).specifier;
            }

            AwareNetworkRequestInformation nnri = mNetworkRequestsCache.get(networkSpecifier);
            if (nnri == null) {
                Log.e(TAG, "WifiAwareNetworkFactory.releaseNetworkFor: networkRequest="
                        + networkRequest + " not in cache!?");
                return;
            }

            if (nnri.networkAgent != null) {
                if (VDBG) {
                    Log.v(TAG, "WifiAwareNetworkFactory.releaseNetworkFor: networkRequest="
                            + networkRequest + ", nnri=" + nnri
                            + ": agent already created - deferring ending data-path to agent"
                            + ".unwanted()");
                }
                return;
            }

            if (nnri.role == WifiAwareManager.WIFI_AWARE_DATA_PATH_ROLE_INITIATOR && nnri.state
                    > AwareNetworkRequestInformation.STATE_INITIATOR_WAIT_FOR_REQUEST_RESPONSE) {
                mMgr.endDataPath(nnri.ndpId);
            }
            if (nnri.role == WifiAwareManager.WIFI_AWARE_DATA_PATH_ROLE_RESPONDER && nnri.state
                    > AwareNetworkRequestInformation.STATE_RESPONDER_WAIT_FOR_REQUEST) {
                mMgr.endDataPath(nnri.ndpId);
            }

            // Will get a callback (on both initiator and responder) when data-path actually
            // terminated. At that point will inform the agent and will clear the cache.
        }
    }

    private class WifiAwareNetworkAgent extends NetworkAgent {
        private NetworkInfo mNetworkInfo;
        private String mNetworkSpecifier;
        private int mNdpId;

        WifiAwareNetworkAgent(Looper looper, Context context, String logTag, NetworkInfo ni,
                NetworkCapabilities nc, LinkProperties lp, int score, String networkSpecifier,
                int ndpId) {
            super(looper, context, logTag, ni, nc, lp, score);

            mNetworkInfo = ni;
            mNetworkSpecifier = networkSpecifier;
            mNdpId = ndpId;
        }

        @Override
        protected void unwanted() {
            if (VDBG) {
                Log.v(TAG, "WifiAwareNetworkAgent.unwanted: networkSpecifier=" + mNetworkSpecifier
                        + ", ndpId=" + mNdpId);
            }

            mMgr.endDataPath(mNdpId);

            // Will get a callback (on both initiator and responder) when data-path actually
            // terminated. At that point will inform the agent and will clear the cache.
        }

        void reconfigureAgentAsDisconnected() {
            if (VDBG) {
                Log.v(TAG, "WifiAwareNetworkAgent.reconfigureAgentAsDisconnected: networkSpecifier="
                        + mNetworkSpecifier + ", ndpId=" + mNdpId);
            }

            mNetworkInfo.setDetailedState(NetworkInfo.DetailedState.DISCONNECTED, null, "");
            sendNetworkInfo(mNetworkInfo);
        }
    }

    private void tearDownInterface(AwareNetworkRequestInformation nnri) {
        if (VDBG) Log.v(TAG, "tearDownInterface: nnri=" + nnri);

        if (nnri.interfaceName != null && !nnri.interfaceName.isEmpty()) {
            try {
                mNwService.setInterfaceDown(nnri.interfaceName);
            } catch (Exception e) { // NwService throws runtime exceptions for errors
                Log.e(TAG,
                        "tearDownInterface: nnri=" + nnri + ": can't bring interface down - " + e);
            }
        }

        if (nnri.networkAgent != null) {
            nnri.networkAgent.reconfigureAgentAsDisconnected();
        }
    }

    /**
     * Select one of the existing interfaces for the new network request.
     *
     * TODO: for now there is only a single interface - simply pick it.
     */
    private String selectInterfaceForRequest(AwareNetworkRequestInformation req) {
        Iterator<String> it = mInterfaces.iterator();
        if (it.hasNext()) {
            return it.next();
        }

        Log.e(TAG, "selectInterfaceForRequest: req=" + req + " - but no interfaces available!");

        return "";
    }

    /**
     * Select a channel for the network request.
     *
     * TODO: for now simply select channel 6
     */
    private int selectChannelForRequest(AwareNetworkRequestInformation req) {
        return 2437;
    }

    /**
     * Aware network request. State object: contains network request information/state through its
     * lifetime.
     */
    @VisibleForTesting
    public static class AwareNetworkRequestInformation {
        static final int STATE_INITIATOR_IDLE = 100;
        static final int STATE_INITIATOR_WAIT_FOR_REQUEST_RESPONSE = 101;
        static final int STATE_INITIATOR_WAIT_FOR_CONFIRM = 102;
        static final int STATE_INITIATOR_CONFIRMED = 103;

        static final int STATE_RESPONDER_IDLE = 200;
        static final int STATE_RESPONDER_WAIT_FOR_REQUEST = 201;
        static final int STATE_RESPONDER_WAIT_FOR_RESPOND_RESPONSE = 202;
        static final int STATE_RESPONDER_WAIT_FOR_CONFIRM = 203;
        static final int STATE_RESPONDER_CONFIRMED = 204;

        public int state;
        public int role;

        public int uid;
        public String interfaceName;
        public int pubSubId = 0;
        public int peerId = 0;
        public byte[] peerDiscoveryMac = null;
        public byte[] pmk = null;
        public String passphrase = null;
        public int ndpId;
        public byte[] peerDataMac;

        public WifiAwareNetworkAgent networkAgent;

        static AwareNetworkRequestInformation parseNetworkSpecifier(String networkSpecifier,
                WifiAwareStateManager mgr) {
            int type, role, uid, clientId, sessionId = 0, peerId = 0, pubSubId = 0;
            byte[] peerMac = null;
            byte[] pmk = null;
            String passphrase = null;

            if (VDBG) {
                Log.v(TAG, "parseNetworkSpecifier: networkSpecifier=" + networkSpecifier);
            }

            try {
                JSONObject jsonObject = new JSONObject(networkSpecifier);

                // type: always present
                type = jsonObject.getInt(WifiAwareManager.NETWORK_SPECIFIER_KEY_TYPE);
                if (type < 0 || type > WifiAwareManager.NETWORK_SPECIFIER_TYPE_MAX_VALID) {
                    Log.e(TAG, "parseNetworkSpecifier: networkSpecifier=" + networkSpecifier
                            + ", invalid 'type' value");
                    return null;
                }

                // role: always present
                role = jsonObject.getInt(WifiAwareManager.NETWORK_SPECIFIER_KEY_ROLE);
                if (role != WifiAwareManager.WIFI_AWARE_DATA_PATH_ROLE_INITIATOR
                        && role != WifiAwareManager.WIFI_AWARE_DATA_PATH_ROLE_RESPONDER) {
                    Log.e(TAG, "parseNetworkSpecifier: networkSpecifier=" + networkSpecifier
                            + " -- invalid 'role' value");
                    return null;
                }

                if (role == WifiAwareManager.WIFI_AWARE_DATA_PATH_ROLE_INITIATOR
                        && type != WifiAwareManager.NETWORK_SPECIFIER_TYPE_IB
                        && type != WifiAwareManager.NETWORK_SPECIFIER_TYPE_OOB) {
                    Log.e(TAG, "parseNetworkSpecifier: networkSpecifier=" + networkSpecifier
                            + " -- invalid 'type' value for INITIATOR (only IB and OOB are "
                            + "permitted)");
                    return null;
                }

                // clientId: always present
                clientId = jsonObject.getInt(WifiAwareManager.NETWORK_SPECIFIER_KEY_CLIENT_ID);

                // sessionId: present for types IB, IB_ANY_PEER
                if (type == WifiAwareManager.NETWORK_SPECIFIER_TYPE_IB
                        || type == WifiAwareManager.NETWORK_SPECIFIER_TYPE_IB_ANY_PEER) {
                    sessionId = jsonObject.getInt(
                            WifiAwareManager.NETWORK_SPECIFIER_KEY_SESSION_ID);
                }

                // peer Id: present for type IB
                if (type == WifiAwareManager.NETWORK_SPECIFIER_TYPE_IB) {
                    peerId = jsonObject.getInt(WifiAwareManager.NETWORK_SPECIFIER_KEY_PEER_ID);
                }

                // peerMac: present for type OOB
                if (type == WifiAwareManager.NETWORK_SPECIFIER_TYPE_OOB) {
                    try {
                        peerMac = HexEncoding.decode(jsonObject.getString(
                                WifiAwareManager.NETWORK_SPECIFIER_KEY_PEER_MAC).toCharArray(),
                                false);
                        if (peerMac == null || peerMac.length != 6) {
                            Log.e(TAG, "parseNetworkSpecifier: networkSpecifier=" + networkSpecifier
                                    + " -- invalid peer MAC address - null or not 6 bytes");
                            return null;
                        }
                    } catch (IllegalArgumentException e) {
                        Log.e(TAG, "parseNetworkSpecifier: networkSpecifier="
                                + networkSpecifier + " -- invalid peer MAC address -- e=" + e);
                        return null;
                    }
                }

                // pmk: always present (though can be an empty array - equivalent to null)
                pmk = Base64.decode(
                        jsonObject.getString(WifiAwareManager.NETWORK_SPECIFIER_KEY_PMK),
                        Base64.DEFAULT);
                if (pmk != null && pmk.length == 0) {
                    pmk = null;
                }

                // passphrase: always present (though can be an empty string - equivalent to null)
                passphrase = jsonObject.getString(
                        WifiAwareManager.NETWORK_SPECIFIER_KEY_PASSPHRASE);
                if (passphrase != null && passphrase.length() == 0) {
                    passphrase = null;
                }

                if (passphrase != null) {
                    if (pmk != null) {
                        Log.e(TAG, "parseNetworkSpecifier: networkSpecifier=" + networkSpecifier
                                + " -- invalid: can't specify both PMK and Passphrase");
                        return null;
                    }
                }
            } catch (JSONException e) {
                Log.e(TAG, "parseNetworkSpecifier: networkSpecifier=" + networkSpecifier
                        + " -- invalid JSON format -- e=" + e);
                return null;
            }

            // look up network specifier information in Aware state manager
            WifiAwareClientState client = mgr.getClient(clientId);
            if (client == null) {
                Log.e(TAG, "parseNetworkSpecifier: networkSpecifier=" + networkSpecifier
                        + " -- not client with this id -- clientId=" + clientId);
                return null;
            }
            uid = client.getUid();

            // validate the role (if session ID provided: i.e. session 1xx)
            if (type == WifiAwareManager.NETWORK_SPECIFIER_TYPE_IB
                    || type == WifiAwareManager.NETWORK_SPECIFIER_TYPE_IB_ANY_PEER) {
                WifiAwareDiscoverySessionState session = client.getSession(sessionId);
                if (session == null) {
                    Log.e(TAG,
                            "parseNetworkSpecifier: networkSpecifier=" + networkSpecifier
                                    + " -- no session with this id -- sessionId=" + sessionId);
                    return null;
                }

                if ((session.isPublishSession()
                        && role != WifiAwareManager.WIFI_AWARE_DATA_PATH_ROLE_RESPONDER) || (
                        !session.isPublishSession()
                                && role != WifiAwareManager.WIFI_AWARE_DATA_PATH_ROLE_INITIATOR)) {
                    Log.e(TAG, "parseNetworkSpecifier: networkSpecifier=" + networkSpecifier
                            + " -- invalid role for session type");
                    return null;
                }

                if (type == WifiAwareManager.NETWORK_SPECIFIER_TYPE_IB) {
                    pubSubId = session.getPubSubId();
                    String peerMacStr = session.getMac(peerId, null);
                    if (peerMacStr == null) {
                        Log.e(TAG, "parseNetworkSpecifier: networkSpecifier=" + networkSpecifier
                                + " -- no MAC address associated with this peer id -- peerId="
                                + peerId);
                        return null;
                    }
                    try {
                        peerMac = HexEncoding.decode(peerMacStr.toCharArray(), false);
                        if (peerMac == null || peerMac.length != 6) {
                            Log.e(TAG, "parseNetworkSpecifier: networkSpecifier="
                                    + networkSpecifier + " -- invalid peer MAC address");
                            return null;
                        }
                    } catch (IllegalArgumentException e) {
                        Log.e(TAG,
                                "parseNetworkSpecifier: networkSpecifier=" + networkSpecifier
                                        + " -- invalid peer MAC address -- e=" + e);
                        return null;
                    }
                }
            }

            // create container and populate
            AwareNetworkRequestInformation nnri = new AwareNetworkRequestInformation();
            nnri.state = (role == WifiAwareManager.WIFI_AWARE_DATA_PATH_ROLE_INITIATOR)
                    ? AwareNetworkRequestInformation.STATE_INITIATOR_IDLE
                    : AwareNetworkRequestInformation.STATE_RESPONDER_IDLE;
            nnri.role = role;
            nnri.uid = uid;
            nnri.pubSubId = pubSubId;
            nnri.peerId = peerId;
            nnri.peerDiscoveryMac = peerMac;
            nnri.pmk = pmk;
            nnri.passphrase = passphrase;

            return nnri;
        }

        @Override
        public String toString() {
            StringBuilder sb = new StringBuilder("AwareNetworkRequestInformation: ");
            sb.append("state=").append(state).append(", role=").append(role).append(
                    ", uid=").append(uid).append(", interfaceName=").append(interfaceName).append(
                    ", pubSubId=").append(pubSubId).append(", peerDiscoveryMac=").append(
                    peerDiscoveryMac == null ? ""
                            : String.valueOf(HexEncoding.encode(peerDiscoveryMac))).append(
                    ", ndpId=").append(ndpId).append(", peerDataMac=").append(
                    peerDataMac == null ? "" : String.valueOf(HexEncoding.encode(peerDataMac)));
            return sb.toString();
        }
    }

    /**
     * Enables mocking.
     */
    @VisibleForTesting
    public class NetworkInterfaceWrapper {
        /**
         * Configures network agent properties: link-local address, connected status, interface
         * name. Delegated to enable mocking.
         */
        public boolean configureAgentProperties(AwareNetworkRequestInformation nnri,
                String networkSpecifier, int ndpId, NetworkInfo networkInfo,
                NetworkCapabilities networkCapabilities, LinkProperties linkProperties) {
            // find link-local address
            InetAddress linkLocal = null;
            NetworkInterface ni;
            try {
                ni = NetworkInterface.getByName(nnri.interfaceName);
            } catch (SocketException e) {
                Log.e(TAG, "onDataPathConfirm: ACCEPT nnri=" + nnri
                        + ": can't get network interface - " + e);
                mMgr.endDataPath(ndpId);
                return false;
            }
            if (ni == null) {
                Log.e(TAG, "onDataPathConfirm: ACCEPT nnri=" + nnri
                        + ": can't get network interface (null)");
                mMgr.endDataPath(ndpId);
                return false;
            }
            Enumeration<InetAddress> addresses = ni.getInetAddresses();
            while (addresses.hasMoreElements()) {
                InetAddress ip = addresses.nextElement();
                if (ip instanceof Inet6Address && ip.isLinkLocalAddress()) {
                    linkLocal = ip;
                    break;
                }
            }

            if (linkLocal == null) {
                Log.e(TAG, "onDataPathConfirm: ACCEPT nnri=" + nnri + ": no link local addresses");
                mMgr.endDataPath(ndpId);
                return false;
            }

            // configure agent
            networkInfo.setIsAvailable(true);
            networkInfo.setDetailedState(NetworkInfo.DetailedState.CONNECTED, null, null);

            networkCapabilities.setNetworkSpecifier(new StringNetworkSpecifier(networkSpecifier));

            linkProperties.setInterfaceName(nnri.interfaceName);
            linkProperties.addLinkAddress(new LinkAddress(linkLocal, 64));
            linkProperties.addRoute(
                    new RouteInfo(new IpPrefix("fe80::/64"), null, nnri.interfaceName));

            return true;
        }
    }

    /**
     * Dump the internal state of the class.
     */
    public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
        pw.println("WifiAwareDataPathStateManager:");
        pw.println("  mInterfaces: " + mInterfaces);
        pw.println("  mNetworkCapabilitiesFilter: " + mNetworkCapabilitiesFilter);
        pw.println("  mNetworkRequestsCache: " + mNetworkRequestsCache);
        pw.println("  mNetworkFactory:");
        mNetworkFactory.dump(fd, pw, args);
    }
}