Android 9.0 网络之netd详解

                case WifiMonitor.NETWORK_CONNECTION_EVENT:
                    if (mVerboseLoggingEnabled) log("Network connection established");
                    mLastNetworkId = message.arg1;
                    mWifiConfigManager.clearRecentFailureReason(mLastNetworkId);
                    mLastBssid = (String) message.obj;
                    reasonCode = message.arg2;
                    // TODO: This check should not be needed after WifiStateMachinePrime refactor.
                    // Currently, the last connected network configuration is left in
                    // wpa_supplicant, this may result in wpa_supplicant initiating connection
                    // to it after a config store reload. Hence the old network Id lookups may not
                    // work, so disconnect the network and let network selector reselect a new
                    // network.
                    config = getCurrentWifiConfiguration();
                    if (config != null) {
                        mWifiInfo.setBSSID(mLastBssid);
                        mWifiInfo.setNetworkId(mLastNetworkId);
                        mWifiInfo.setMacAddress(mWifiNative.getMacAddress(mInterfaceName));

                        ScanDetailCache scanDetailCache =
                                mWifiConfigManager.getScanDetailCacheForNetwork(config.networkId);
                        if (scanDetailCache != null && mLastBssid != null) {
                            ScanResult scanResult = scanDetailCache.getScanResult(mLastBssid);
                            if (scanResult != null) {
                                mWifiInfo.setFrequency(scanResult.frequency);
                            }
                        }
                        mWifiConnectivityManager.trackBssid(mLastBssid, true, reasonCode);
                        // We need to get the updated pseudonym from supplicant for EAP-SIM/AKA/AKA'
                        if (config.enterpriseConfig != null
                                && TelephonyUtil.isSimEapMethod(
                                        config.enterpriseConfig.getEapMethod())) {
                            String anonymousIdentity =
                                    mWifiNative.getEapAnonymousIdentity(mInterfaceName);
                            if (anonymousIdentity != null) {
                                config.enterpriseConfig.setAnonymousIdentity(anonymousIdentity);
                            } else {
                                Log.d(TAG, "Failed to get updated anonymous identity"
                                        + " from supplicant, reset it in WifiConfiguration.");
                                config.enterpriseConfig.setAnonymousIdentity(null);
                            }
                            mWifiConfigManager.addOrUpdateNetwork(config, Process.WIFI_UID);
                        }
                        sendNetworkStateChangeBroadcast(mLastBssid);
                        transitionTo(mObtainingIpState);
                    } else {
                        logw("Connected to unknown networkId " + mLastNetworkId
                                + ", disconnecting...");
                        sendMessage(CMD_DISCONNECT);
                    }
                    break;

    class ObtainingIpState extends State {
        @Override
        public void enter() {
            final WifiConfiguration currentConfig = getCurrentWifiConfiguration();
            final boolean isUsingStaticIp =
                    (currentConfig.getIpAssignment() == IpConfiguration.IpAssignment.STATIC);
            if (mVerboseLoggingEnabled) {
                final String key = currentConfig.configKey();
                log("enter ObtainingIpState netId=" + Integer.toString(mLastNetworkId)
                        + " " + key + " "
                        + " roam=" + mIsAutoRoaming
                        + " static=" + isUsingStaticIp);
            }

            // Send event to CM & network change broadcast
            setNetworkDetailedState(DetailedState.OBTAINING_IPADDR);

            // We must clear the config BSSID, as the wifi chipset may decide to roam
            // from this point on and having the BSSID specified in the network block would
            // cause the roam to fail and the device to disconnect.
            clearTargetBssid("ObtainingIpAddress");

            // Stop IpClient in case we're switching from DHCP to static
            // configuration or vice versa.
            //
            // TODO: Only ever enter this state the first time we connect to a
            // network, never on switching between static configuration and
            // DHCP. When we transition from static configuration to DHCP in
            // particular, we must tell ConnectivityService that we're
            // disconnected, because DHCP might take a long time during which
            // connectivity APIs such as getActiveNetworkInfo should not return
            // CONNECTED.
            stopIpClient();

            mIpClient.setHttpProxy(currentConfig.getHttpProxy());
            if (!TextUtils.isEmpty(mTcpBufferSizes)) {
                mIpClient.setTcpBufferSizes(mTcpBufferSizes);
            }
            final IpClient.ProvisioningConfiguration prov;
            if (!isUsingStaticIp) {
               prov = IpClient.buildProvisioningConfiguration() .withPreDhcpAction() .withApfCapabilities(mWifiNative.getApfCapabilities(mInterfaceName)) .withNetwork(getCurrentNetwork()) .withDisplayName(currentConfig.SSID) .withRandomMacAddress() .build();
            } else {
                StaticIpConfiguration staticIpConfig = currentConfig.getStaticIpConfiguration();
                prov = IpClient.buildProvisioningConfiguration()
                            .withStaticConfiguration(staticIpConfig)
                            .withApfCapabilities(mWifiNative.getApfCapabilities(mInterfaceName))
                            .withNetwork(getCurrentNetwork())
                            .withDisplayName(currentConfig.SSID)
                            .build();
            }
            mIpClient.startProvisioning(prov);            // Get Link layer stats so as we get fresh tx packet counters
            getWifiLinkLayerStats();
        }

        @Override
        public boolean processMessage(Message message) {
            logStateAndMessage(message, this);

            switch(message.what) {
                case CMD_START_CONNECT:
                case CMD_START_ROAM:
                    messageHandlingStatus = MESSAGE_HANDLING_STATUS_DISCARD;
                    break;
                case WifiManager.SAVE_NETWORK:
                    messageHandlingStatus = MESSAGE_HANDLING_STATUS_DEFERRED;
                    deferMessage(message);
                    break;
                case WifiMonitor.NETWORK_DISCONNECTION_EVENT:
                    reportConnectionAttemptEnd(
                            WifiMetrics.ConnectionEvent.FAILURE_NETWORK_DISCONNECTION,
                            WifiMetricsProto.ConnectionEvent.HLF_NONE);
                    return NOT_HANDLED;
                case CMD_SET_HIGH_PERF_MODE:
                    messageHandlingStatus = MESSAGE_HANDLING_STATUS_DEFERRED;
                    deferMessage(message);
                    break;
                default:
                    return NOT_HANDLED;
            }
            return HANDLED;
        }
    }

    public void startProvisioning(ProvisioningConfiguration req) {
        if (!req.isValid()) {
            doImmediateProvisioningFailure(IpManagerEvent.ERROR_INVALID_PROVISIONING);
            return;
        }
 
        mInterfaceParams = mDependencies.getInterfaceParams(mInterfaceName);
        if (mInterfaceParams == null) {
            logError("Failed to find InterfaceParams for " + mInterfaceName);
            doImmediateProvisioningFailure(IpManagerEvent.ERROR_INTERFACE_NOT_FOUND);
            return;
        }
 
        mCallback.setNeighborDiscoveryOffload(true);
        sendMessage(CMD_START, new ProvisioningConfiguration(req));
    }

    class RunningState extends State {
        private ConnectivityPacketTracker mPacketTracker;
        private boolean mDhcpActionInFlight;

        @Override
        public void enter() {
            ApfFilter.ApfConfiguration apfConfig = new ApfFilter.ApfConfiguration();
            apfConfig.apfCapabilities = mConfiguration.mApfCapabilities;
            apfConfig.multicastFilter = mMulticastFiltering;
            // Get the Configuration for ApfFilter from Context
            apfConfig.ieee802_3Filter =
                    mContext.getResources().getBoolean(R.bool.config_apfDrop802_3Frames);
            apfConfig.ethTypeBlackList =
                    mContext.getResources().getIntArray(R.array.config_apfEthTypeBlackList);
            mApfFilter = ApfFilter.maybeCreate(mContext, apfConfig, mInterfaceParams, mCallback);
            // TODO: investigate the effects of any multicast filtering racing/interfering with the
            // rest of this IP configuration startup.
            if (mApfFilter == null) {
                mCallback.setFallbackMulticastFilter(mMulticastFiltering);
            }

            mPacketTracker = createPacketTracker();
            if (mPacketTracker != null) mPacketTracker.start(mConfiguration.mDisplayName);

            if (mConfiguration.mEnableIPv6 && !startIPv6()) {
                doImmediateProvisioningFailure(IpManagerEvent.ERROR_STARTING_IPV6);
                transitionTo(mStoppingState);
                return;
            }

            if (mConfiguration.mEnableIPv4 && !startIPv4()) {
                doImmediateProvisioningFailure(IpManagerEvent.ERROR_STARTING_IPV4);
                transitionTo(mStoppingState);
                return;
            }

            final InitialConfiguration config = mConfiguration.mInitialConfig;
            if ((config != null) && !applyInitialConfig(config)) {
                // TODO introduce a new IpManagerEvent constant to distinguish this error case.
                doImmediateProvisioningFailure(IpManagerEvent.ERROR_INVALID_PROVISIONING);
                transitionTo(mStoppingState);
                return;
            }

            if (mConfiguration.mUsingMultinetworkPolicyTracker) {
                mMultinetworkPolicyTracker = new MultinetworkPolicyTracker(
                        mContext, getHandler(),
                        () -> { mLog.log("OBSERVED AvoidBadWifi changed"); });
                mMultinetworkPolicyTracker.start();
            }

            if (mConfiguration.mUsingIpReachabilityMonitor && !startIpReachabilityMonitor()) {
                doImmediateProvisioningFailure(
                        IpManagerEvent.ERROR_STARTING_IPREACHABILITYMONITOR);
                transitionTo(mStoppingState);
                return;
            }
        }

    private boolean startIPv4() {
        // If we have a StaticIpConfiguration attempt to apply it and
        // handle the result accordingly.
        if (mConfiguration.mStaticIpConfig != null) {
            if (mInterfaceCtrl.setIPv4Address(mConfiguration.mStaticIpConfig.ipAddress)) {
                handleIPv4Success(new DhcpResults(mConfiguration.mStaticIpConfig));
            } else {
                return false;
            }
        } else {
            // Start DHCPv4.
            mDhcpClient = DhcpClient.makeDhcpClient(mContext, IpClient.this, mInterfaceParams);
            mDhcpClient.registerForPreDhcpNotification();
 mDhcpClient.sendMessage(DhcpClient.CMD_START_DHCP);
        }

        return true;
    }

    class StoppedState extends State {
        @Override
        public boolean processMessage(Message message) {
            switch (message.what) {
                case CMD_START_DHCP:
                    if (mRegisteredForPreDhcpNotification) {
                        transitionTo(mWaitBeforeStartState);
                    } else {
                        transitionTo(mDhcpInitState);
                    }
                    return HANDLED;
                default:
                    return NOT_HANDLED;
            }
        }
    }
 
    private State mWaitBeforeStartState = new WaitBeforeStartState(mDhcpInitState);
 
 
    // Sends CMD_PRE_DHCP_ACTION to the controller, waits for the controller to respond with
    // CMD_PRE_DHCP_ACTION_COMPLETE, and then transitions to mOtherState.
    abstract class WaitBeforeOtherState extends LoggingState {
        protected State mOtherState;
 
        @Override
        public void enter() {
            super.enter();
            mController.sendMessage(CMD_PRE_DHCP_ACTION);
        }
 
        @Override
        public boolean processMessage(Message message) {
            super.processMessage(message);
            switch (message.what) {
                case CMD_PRE_DHCP_ACTION_COMPLETE:
                    transitionTo(mOtherState);
                    return HANDLED;
                default:
                    return NOT_HANDLED;
            }
        }
    }

                case DhcpClient.CMD_CONFIGURE_LINKADDRESS: {
                    final LinkAddress ipAddress = (LinkAddress) msg.obj;
                    if (mInterfaceCtrl.setIPv4Address(ipAddress)) {
                        mDhcpClient.sendMessage(DhcpClient.EVENT_LINKADDRESS_CONFIGURED);
                    } else {
                        logError("Failed to set IPv4 address.");
                        dispatchCallback(ProvisioningChange.LOST_PROVISIONING,
                                new LinkProperties(mLinkProperties));
                        transitionTo(mStoppingState);
                    }
                    break;
                }

    class DhcpInitState extends PacketRetransmittingState {
        public DhcpInitState() {
            super();
        }
 
        @Override
        public void enter() {
            super.enter();
            startNewTransaction();
            mLastInitEnterTime = SystemClock.elapsedRealtime();
        }
 
        protected boolean sendPacket() {
            return sendDiscoverPacket();
        }
 
        protected void receivePacket(DhcpPacket packet) {
            if (!isValidPacket(packet)) return;
            if (!(packet instanceof DhcpOfferPacket)) return;
            mOffer = packet.toDhcpResults();
            if (mOffer != null) {
                Log.d(TAG, "Got pending lease: " + mOffer);
                transitionTo(mDhcpRequestingState);
            }
        }
    }

    private void notifySuccess() {
        mController.sendMessage(
                CMD_POST_DHCP_ACTION, DHCP_SUCCESS, 0, new DhcpResults(mDhcpLease));
    }
 
 
    private void acceptDhcpResults(DhcpResults results, String msg) {
        mDhcpLease = results;
        mOffer = null;
        Log.d(TAG, msg + " lease: " + mDhcpLease);
        notifySuccess();
    }
 
    class DhcpRequestingState extends PacketRetransmittingState {
        public DhcpRequestingState() {
            mTimeout = DHCP_TIMEOUT_MS / 2;
        }
 
        protected boolean sendPacket() {
            return sendRequestPacket(
                    INADDR_ANY,                                    // ciaddr
                    (Inet4Address) mOffer.ipAddress.getAddress(),  // DHCP_REQUESTED_IP
                    (Inet4Address) mOffer.serverAddress,           // DHCP_SERVER_IDENTIFIER
                    INADDR_BROADCAST);                             // packet destination address
        }
 
        protected void receivePacket(DhcpPacket packet) {
            if (!isValidPacket(packet)) return;
            if ((packet instanceof DhcpAckPacket)) {
                DhcpResults results = packet.toDhcpResults();
                if (results != null) {
                    setDhcpLeaseExpiry(packet);
                    acceptDhcpResults(results, "Confirmed");
                    transitionTo(mConfiguringInterfaceState);
                }
            } else if (packet instanceof DhcpNakPacket) {
                // TODO: Wait a while before returning into INIT state.
                Log.d(TAG, "Received NAK, returning to INIT");
                mOffer = null;
                transitionTo(mDhcpInitState);
            }
        }

                case DhcpClient.CMD_POST_DHCP_ACTION:
                    stopDhcpAction();
 
                    switch (msg.arg1) {
                        case DhcpClient.DHCP_SUCCESS:
                            handleIPv4Success((DhcpResults) msg.obj);
                            break;
                        case DhcpClient.DHCP_FAILURE:
                            handleIPv4Failure();
                            break;
                        default:
                            logError("Unknown CMD_POST_DHCP_ACTION status: %s", msg.arg1);
                    }
                    break;

        @Override
        public void onProvisioningSuccess(LinkProperties newLp) {
            mWifiMetrics.logStaEvent(StaEvent.TYPE_CMD_IP_CONFIGURATION_SUCCESSFUL);
            sendMessage(CMD_UPDATE_LINKPROPERTIES, newLp);
            sendMessage(CMD_IP_CONFIGURATION_SUCCESSFUL);
        }

service netd /system/bin/netd
    class main
    socket netd stream 0660 root system
    socket dnsproxyd stream 0660 root inet
    socket mdns stream 0660 root system
    socket fwmarkd stream 0660 root inet
    onrestart restart zygote
    onrestart restart zygote_secondary

int main() {
    using android::net::gCtls;
    Stopwatch s;

    ALOGI("Netd 1.0 starting");
    remove_pid_file();

    blockSigpipe();

    // Before we do anything that could fork, mark CLOEXEC the UNIX sockets that we get from init.
    // FrameworkListener does this on initialization as well, but we only initialize these
    // components after having initialized other subsystems that can fork.
    for (const auto& sock : { CommandListener::SOCKET_NAME,
                              DnsProxyListener::SOCKET_NAME,
                              FwmarkServer::SOCKET_NAME,
                              MDnsSdListener::SOCKET_NAME }) {
        setCloseOnExec(sock);
    }

    NetlinkManager *nm = NetlinkManager::Instance();
    if (nm == nullptr) {
        ALOGE("Unable to create NetlinkManager");
        exit(1);
    };

    gCtls = new android::net::Controllers();
    gCtls->init();

    CommandListener cl;
    nm->setBroadcaster((SocketListener *) &cl);

    if (nm->start()) {
        ALOGE("Unable to start NetlinkManager (%s)", strerror(errno));
        exit(1);
    }

    std::unique_ptr<NFLogListener> logListener;
    {
        auto result = makeNFLogListener();
        if (!isOk(result)) {
            ALOGE("Unable to create NFLogListener: %s", toString(result).c_str());
            exit(1);
        }
        logListener = std::move(result.value());
        auto status = gCtls->wakeupCtrl.init(logListener.get());
        if (!isOk(result)) {
            ALOGE("Unable to init WakeupController: %s", toString(result).c_str());
            // We can still continue without wakeup packet logging.
        }
    }

    // Set local DNS mode, to prevent bionic from proxying
    // back to this service, recursively.
    setenv("ANDROID_DNS_MODE", "local", 1);
    DnsProxyListener dpl(&gCtls->netCtrl, &gCtls->eventReporter);
    if (dpl.startListener()) {
        ALOGE("Unable to start DnsProxyListener (%s)", strerror(errno));
        exit(1);
    }

    MDnsSdListener mdnsl;
    if (mdnsl.startListener()) {
        ALOGE("Unable to start MDnsSdListener (%s)", strerror(errno));
        exit(1);
    }

    FwmarkServer fwmarkServer(&gCtls->netCtrl, &gCtls->eventReporter, &gCtls->trafficCtrl);
    if (fwmarkServer.startListener()) {
        ALOGE("Unable to start FwmarkServer (%s)", strerror(errno));
        exit(1);
    }

    Stopwatch subTime;
    status_t ret;
    if ((ret = NetdNativeService::start()) != android::OK) {
        ALOGE("Unable to start NetdNativeService: %d", ret);
        exit(1);
    }
    ALOGI("Registering NetdNativeService: %.1fms", subTime.getTimeAndReset());

    /*
     * Now that we're up, we can respond to commands. Starting the listener also tells
     * NetworkManagementService that we are up and that our binder interface is ready.
     */
    if (cl.startListener()) {
        ALOGE("Unable to start CommandListener (%s)", strerror(errno));
        exit(1);
    }
    ALOGI("Starting CommandListener: %.1fms", subTime.getTimeAndReset());

    write_pid_file();

    // Now that netd is ready to process commands, advertise service
    // availability for HAL clients.
    NetdHwService mHwSvc;
    if ((ret = mHwSvc.start()) != android::OK) {
        ALOGE("Unable to start NetdHwService: %d", ret);
        exit(1);
    }
    ALOGI("Registering NetdHwService: %.1fms", subTime.getTimeAndReset());

    ALOGI("Netd started in %dms", static_cast<int>(s.timeTaken()));

    IPCThreadState::self()->joinThreadPool();

    ALOGI("Netd exiting");

    remove_pid_file();

    exit(0);
}

// SystemServer.java
       if (!disableNetwork) {
           traceBeginAndSlog("StartNetworkManagementService");
           try {
               networkManagement = NetworkManagementService.create(context);
               ServiceManager.addService(Context.NETWORKMANAGEMENT_SERVICE, networkManagement);
           } catch (Throwable e) {
               reportWtf("starting NetworkManagement Service", e);
           }
           traceEnd();
       }

 static NetworkManagementService create(Context context, String socket)
        throws InterruptedException {
    final NetworkManagementService service = new NetworkManagementService(context, socket);
    final CountDownLatch connectedSignal = service.mConnectedSignal;
    if (DBG) Slog.d(TAG, "Creating NetworkManagementService");
    service.mThread.start();
    if (DBG) Slog.d(TAG, "Awaiting socket connection");
    connectedSignal.await();
    service.connectNativeNetdService();

    return service;
    }
    

       private NetworkManagementService(Context context, String socket) {
    mContext = context;

    // make sure this is on the same looper as our NativeDaemonConnector for sync purposes
    mFgHandler = new Handler(FgThread.get().getLooper());

    // Don't need this wake lock, since we now have a time stamp for when
    // the network actually went inactive.  (It might be nice to still do this,
    // but I don't want to do it through the power manager because that pollutes the
    // battery stats history with pointless noise.)
    //PowerManager pm = (PowerManager)context.getSystemService(Context.POWER_SERVICE);
    PowerManager.WakeLock wl = null; //pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, NETD_TAG);

    mConnector = new NativeDaemonConnector(
        new NetdCallbackReceiver(), socket, 10, NETD_TAG, 160, wl,
        FgThread.get().getLooper());
    mThread = new Thread(mConnector, NETD_TAG);

    mDaemonHandler = new Handler(FgThread.get().getLooper());

    // Add ourself to the Watchdog monitors.
    Watchdog.getInstance().addMonitor(this);

    LocalServices.addService(NetworkManagementInternal.class, new LocalService());

    synchronized (mTetheringStatsProviders) {
        mTetheringStatsProviders.put(new NetdTetheringStatsProvider(), "netd");
    }
}

@Override
public void setInterfaceConfig(String iface, InterfaceConfiguration cfg) {
    mContext.enforceCallingOrSelfPermission(CONNECTIVITY_INTERNAL, TAG);
    LinkAddress linkAddr = cfg.getLinkAddress();
    if (linkAddr == null || linkAddr.getAddress() == null) {
        throw new IllegalStateException("Null LinkAddress given");
    }

    final Command cmd = new Command("interface", "setcfg", iface,
            linkAddr.getAddress().getHostAddress(),
            linkAddr.getPrefixLength());
    for (String flag : cfg.getFlags()) {
        cmd.appendArg(flag);
    }

    try {
        mConnector.execute(cmd);
    } catch (NativeDaemonConnectorException e) {
        throw e.rethrowAsParcelableException();
    }

int main(int argc, char **argv) {
    //argv[1]可以是socket name.
    if ((sock = socket_local_client(argv[1],
                                     ANDROID_SOCKET_NAMESPACE_RESERVED,
                                     SOCK_STREAM)) < 0) {
        //如果不传，那么默认就是name为"netd"的socket                   
        if ((sock = socket_local_client("netd",
                                         ANDROID_SOCKET_NAMESPACE_RESERVED,
                                         SOCK_STREAM)) < 0) {
            fprintf(stderr, "Error connecting (%s)\n", strerror(errno));
            exit(4);
        }
    }
    exit(do_cmd(sock, argc-cmdOffset, &(argv[cmdOffset])));
} 

static int do_cmd(int sock, int argc, char **argv) {
　　　//命令参数最终通过socket发送给netd服务进程处理
   if (write(sock, final_cmd, strlen(final_cmd) + 1) < 0) {
        int res = errno;
        perror("write");
        free(final_cmd);
        return res;
    }
}

console:/ # ndc interface list
110 0 dummy0 110 0 eth0 110 0 ip6_vti0 110 0 ip6tnl0 110 0 ip_vti0 110 0 lo 200 0 Interface list completed