Android WiFi code

 

1． Architecture

Application layer: Settings/other app

Framework:  Android Framework

Native C:  wpa_supplicant, netd/hostapd/netlink

Kernel: WLAN STA/AP/P2P driver

 

2.  Code path

packages\apps\Settings\src\com\android\settings\wifi

frameworks/base/services/java/com/android/server/WifiService.java

frameworks/base/wifi/java/android/net/wifi/

(WifiManager.java, WifiStateMachine.java, WifiStateTracker.java, WifiInfo.java, WifiMonitor.java, WifiNative.java)

frameworks/base/wifi/java/android/net/wifi/p2p/

frameworks/base/core/jni/android_net_wifi_Wifi.cpp

hardware/libhardware_legary/wifi/wifi.c

system/netd

external/dhcpcd

external/wpa_supplicant_8

 

3. WifiManager

public static final int WIFI_STATE_DISABLING = 0;

public static final int WIFI_STATE_DISABLED = 1;

public static final int WIFI_STATE_ENABLING = 2;

public static final int WIFI_STATE_ENABLED = 3

public static final int WIFI_STATE_UNKNOWN = 4

 

public static final int WIFI_AP_STATE_DISABLING = 10;

public static final int WIFI_AP_STATE_DISABLED = 11;

public static final int WIFI_AP_STATE_ENABLING = 12;

public static final int WIFI_AP_STATE_ENABLED = 13;

public static final int WIFI_AP_STATE_FAILED = 14

 

setWifiEnabled

startWifi/stopWifi

startScan

setWifiApEnabled

getWifiState

getWifiApState

setFrequencyBand(WIFI_FREQUENCY_BAND_2GHZ)

 

Supplicant state: SupplicantState

WifiInfo & networkInfo use DetailedState

stateMap.put(SupplicantState.DISCONNECTED, DetailedState.DISCONNECTED);

stateMap.put(SupplicantState.INTERFACE_DISABLED, DetailedState.DISCONNECTED);

stateMap.put(SupplicantState.INACTIVE, DetailedState.IDLE);

stateMap.put(SupplicantState.SCANNING, DetailedState.SCANNING);

stateMap.put(SupplicantState.AUTHENTICATING, DetailedState.CONNECTING);

stateMap.put(SupplicantState.ASSOCIATING, DetailedState.CONNECTING);

stateMap.put(SupplicantState.ASSOCIATED, DetailedState.CONNECTING);

stateMap.put(SupplicantState.FOUR_WAY_HANDSHAKE, DetailedState.AUTHENTICATING);

stateMap.put(SupplicantState.GROUP_HANDSHAKE, DetailedState.AUTHENTICATING);

stateMap.put(SupplicantState.COMPLETED, DetailedState.OBTAINING_IPADDR);

stateMap.put(SupplicantState.DORMANT, DetailedState.DISCONNECTED);

stateMap.put(SupplicantState.UNINITIALIZED, DetailedState.IDLE);

stateMap.put(SupplicantState.INVALID, DetailedState.FAILED);

 

 4. WifiStateMachine.java

addState(mDefaultState);

    addState(mInitialState, mDefaultState);

    addState(mDriverUnloadingState, mDefaultState);

    addState(mDriverUnloadedState, mDefaultState);

        addState(mDriverFailedState, mDriverUnloadedState);

    addState(mDriverLoadingState, mDefaultState);

    addState(mDriverLoadedState, mDefaultState);

    addState(mSupplicantStartingState, mDefaultState);

    addState(mSupplicantStartedState, mDefaultState);

        addState(mDriverStartingState, mSupplicantStartedState);

        addState(mDriverStartedState, mSupplicantStartedState);

            addState(mScanModeState, mDriverStartedState);

            addState(mConnectModeState, mDriverStartedState);

                addState(mL2ConnectedState, mConnectModeState);

                    addState(mObtainingIpState, mL2ConnectedState);

                    addState(mVerifyingLinkState, mL2ConnectedState);

                    addState(mCaptivePortalCheckState, mL2ConnectedState);

                    addState(mConnectedState, mL2ConnectedState);

                addState(mDisconnectingState, mConnectModeState);

                addState(mDisconnectedState, mConnectModeState);

                addState(mWpsRunningState, mConnectModeState);

        addState(mWaitForP2pDisableState, mSupplicantStartedState);

        addState(mDriverStoppingState, mSupplicantStartedState);

        addState(mDriverStoppedState, mSupplicantStartedState);

    addState(mSupplicantStoppingState, mDefaultState);

    addState(mSoftApStartingState, mDefaultState);

    addState(mSoftApStartedState, mDefaultState);

        addState(mTetheringState, mSoftApStartedState);

        addState(mTetheredState, mSoftApStartedState);

    addState(mSoftApStoppingState, mDefaultState);

 

setInitialState(mInitialState);

 

5. Logs

.Adb logcat (main/system/events)

. dmesg   adb shell dmesg

adb shell cat /proc/kmsg

. sniffer & tcpdump

adb shell tcpdump -i wlan0 -w /data/wlan.pcap

 

6.  Wifi development

6.1 permission

<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" >   </uses-permission>

<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" >      </uses-permission>

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" >   </uses-permission>

<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" >      </uses-permission>

<uses-permission android:name="android.permission.UPDATE_DEVICE_STATS" >    </uses-permission>

<uses-permission android:name="android.permission.INTERNET" >               </uses-permission>

6.2  get WIFI_SERVICE, enable Wifi

WifiManager mWifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);

if (!mWifiManager.isWifiEnabled()) {

   wifiManager.setWifiEnabled(true);

}

6.3  start Scan

registerReceiver(wifiReceiver, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));

mWifiManager.startScan();

 

6.4 Wifi State

Three ways to get Wifi State.

WifiManager wifiManager = (WifiManager)getSystemService(WIFI_SERVICE);

WifiInfo wifiInfo = wifiManager.getConnectionInfo();

int state = wifiInfo.getDetailedStateOf();

 

ConnectivityManager cm = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE); 

NetworkInfo networkInfo = cm.getNetworkInfo(ConnectivityManager.TYPE_WIFI); 

isConnected = (networkInfo != null &&  networkInfo.isConnected());

 

Listen WifiManager.NETWORK_STATE_CHANGED_ACTION

filter.addAction(WifiManager.NETWORK_STATE_CHANGED_ACTION);

mContext.registerReceiver(new WifiStateReceiver(), filter);

 

public void onReceive(Context context, Intent intent) {

if (intent.getAction().equals(WifiManager.NETWORK_STATE_CHANGED_ACTION)) {

    NetworkInfo info = (NetworkInfo) intent.getParcelableExtra(WifiManager.EXTRA_NETWORK_INFO); 

    boolean isWifiConnected = (info != null && info.isConnected()); 

}

}

  

7. WiFi spec

http://www.wi-fi.org/