浅析android下如何通过jni监控wifi网络连接、dhcpcd执行和power电源控制

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libs/ android_runtime/ android_net_wifi_Wifi. cpp
部分jni接口
static JNINativeMethod gWifiMethods[ ] = {
{ "loadDriver" , "()Z" , ( void * ) android_net_wifi_loadDriver} ,
{ "setPowerModeCommand" , "(I)Z" , ( void * ) android_net_wifi_setPowerModeCommand} , //电源管理
{ "connectToSupplicant" , "()Z" , ( void * ) android_net_wifi_connectToSupplicant} ,
{ "waitForEvent" , "()Ljava/lang/String;" , ( void * ) android_net_wifi_waitForEvent} ,
{ "disconnectCommand" , "()Z" , ( void * ) android_net_wifi_disconnectCommand} ,
. . .
} ;
int register_android_net_wifi_WifiManager( JNIEnv* env )
{
. . .
return AndroidRuntime: : registerNativeMethods( env ,
WIFI_PKG_NAME, gWifiMethods, NELEM( gWifiMethods) ) ; //登记jni
}
libs/ android_runtime/ AndroidRuntime. cpp
static const RegJNIRec gRegJNI[ ] = {
. . .
REG_JNI( register_android_net_wifi_WifiManager) ,
. . .
} ;
int AndroidRuntime: : startReg( JNIEnv* env )
{
. . .
register_jni_procs( gRegJNI, NELEM( gRegJNI) , env ) ;
. . .
}
AndroidRuntime: : start
= > startReg( env ) 即调用方法int AndroidRuntime: : startReg( JNIEnv* env )
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
wifi_load_driver
wifi_start_supplicant
= > ensure_config_file_exists
//检查/data/misc/wifi/wpa_supplicant.conf文件是否存在,如果不存在,那么从/system/etc/wifi/wpa_supplicant.conf动态拷贝一份
android_net_wifi_connectToSupplicant
= > wifi_connect_to_supplicant
= >
ctrl_conn= wpa_ctrl_open( ifname) ;
monitor_conn= wpa_ctrl_open( ifname) ;
wpa_ctrl_attach( monitor_conn) ;

android_net_wifi_waitForEvent
= > wifi_wait_for_event
= > wpa_ctrl_recv( monitor_conn, buf, & nread) ;
= > recv( ctrl- > s, reply, * reply_len, 0) ; //阻塞等待wpa_supplicant的netlink数据过来
= > 如果接收的buf数据区, buf[ 0] 为'<' , 那么说明有level级别信息, 所以将'<' . . . '>' 数据剔除, 然后wifi_wait_for_event函数返回[ luther. gliethttp] .
java / android/ android/ net / wifi/ WifiMonitor. java
public class WifiMonitor{
. . .
public void startMonitoring( ) {
new MonitorThread( ) . start ( ) ; //启动java线程
}
class MonitorThreadextends Thread {
public MonitorThread( ) {
super ( "WifiMonitor" ) ;
}
public void run ( ) {
for ( ; ; ) {
ensureSupplicantConnection( ) ; //=>WifiNative.connectToSupplicant调用jni函数android_net_wifi_connectToSupplicant
String eventStr= WifiNative. waitForEvent( ) ; //=>调用jni函数android_net_wifi_waitForEvent
//private static final int CONNECTED = 1;
//private static final int DISCONNECTED = 2;
//private static final String eventPrefix = "CTRL-EVENT-";
//private static final int eventPrefixLen = eventPrefix.length();
//private static final String connectedEvent = "CONNECTED";
//private static final String disconnectedEvent = "DISCONNECTED";
String eventName= eventStr. substring ( eventPrefixLen) ; //去掉"CTRL-EVENT-"字符串
int nameEnd= eventName. indexOf ( ' ' ) ; //找到随后的空格位置,这在wpa_supplicant发送时
//#define WPA_EVENT_CONNECTED "CTRL-EVENT-CONNECTED "中,已经内置空格了.
if ( nameEnd! = - 1)
eventName= eventName. substring ( 0, nameEnd) ;
int event ;
if ( eventName. equals ( connectedEvent) ) //检测netlink过来的字符串action类型
event = CONNECTED;
else if ( eventName. equals ( disconnectedEvent) )
event = DISCONNECTED;
. . .
int ind= eventStr. indexOf ( " - " ) ; //CTRL-EVENT-CONNECTED - Connection to ...
if ( ind! = - 1)
eventData= eventStr. substring ( ind+ 3) ;
//剔除前导控制字符,将" - "后面的描述字符串作为真实数据,继续处理
. . .
if ( event = = STATE_CHANGE) {
handleSupplicantStateChange( eventData) ;
} else if ( event = = DRIVER_STATE) {
handleDriverEvent( eventData) ;
} else {
handleEvent ( event , eventData) ; //对于CONNECTED和DISCONNECTED等netlink事件将执行此操作来处理[luther.gliethttp]
// If supplicant is gone, exit the thread
if ( event = = TERMINATING) {
break ;
}
}
. . .
void handleEvent ( int event , String remainder ) {
switch ( event ) {
case DISCONNECTED:
handleNetworkStateChange( NetworkInfo. DetailedState. DISCONNECTED, remainder ) ;
break ;

case CONNECTED:
handleNetworkStateChange( NetworkInfo. DetailedState. CONNECTED, remainder ) ; //控制界面显示
break ;
. . .
}
public class WifiStateTrackerextends NetworkStateTracker{
. . .
public void startEventLoop( ) {
mWifiMonitor. startMonitoring( ) ; //启动上面的MonitorThread线程
}
. . .
}
java / services/ com/ android/ server / WifiService. java
public class WifiServiceextends IWifiManager. Stub {
. . .
private boolean setWifiEnabledBlocking( boolean enable ) {
final int eventualWifiState= enable ? WIFI_STATE_ENABLED: WIFI_STATE_DISABLED;
. . .
if ( enable ) {
if ( WifiNative. loadDriver( ) ) {
Log . e( TAG, "Failed to load Wi-Fi driver." ) ;
updateWifiState( WIFI_STATE_UNKNOWN) ;
return false;
}
if ( WifiNative. startSupplicant( ) ) {
WifiNative. unloadDriver( ) ;
Log . e( TAG, "Failed to start supplicant daemon." ) ;
updateWifiState( WIFI_STATE_UNKNOWN) ;
return false;
}
mWifiStateTracker. startEventLoop( ) ;
//启动MonitorThread线程,等待wpa_supplicant将netlink数据转发过来,然后根据netlink动作类型,进一步影响界面显示[luther.gliethttp].
}
. . .
}
java / android/ android/ net / wifi/ WifiStateTracker. java
电源管理
private void handleConnectedState( ) {
. . .
mDhcpTarget. obtainMessage( EVENT_DHCP_START) . sendToTarget( ) ; //传递到下面的handleMessage方法
. . .
}
public void onChange( boolean selfChange) {
. . .
handleConnectedState( ) ;
. . .
}
public class WifiStateTrackerextends NetworkStateTracker{
. . .
public void handleMessage( Message msg) {
switch ( msg. what) {
case EVENT_SUPPLICANT_CONNECTION:
case EVENT_NETWORK_STATE_CHANGED:
handleConnectedState( ) ; //调用
. . .
private class DhcpHandlerextends Handler {

private Handler mTarget;

public DhcpHandler( Looper looper, Handler target ) {
super ( looper) ;
mTarget= target ;
}

public void handleMessage( Message msg) {
int event ;
//private static final int DRIVER_POWER_MODE_AUTO = 0;
//private static final int DRIVER_POWER_MODE_ACTIVE = 1;
switch ( msg. what) {
case EVENT_DHCP_START:
synchronized ( this ) {
WifiNative. setPowerModeCommand( DRIVER_POWER_MODE_ACTIVE) ; //设置电源模式,调用android_net_wifi_setPowerModeCommand
}
Log . d( TAG, "DhcpHandler: DHCP request started" ) ;
//libs/android_runtime/android_net_NetUtils.cpp
//static JNINativeMethod gNetworkUtilMethods[] = {
//{ "runDhcp", "(Ljava/lang/String;Landroid/net/DhcpInfo;)Z", (void *)android_net_utils_runDhcp },
// ...
//};

if ( NetworkUtils. runDhcp( mInterfaceName, mDhcpInfo) ) { //执行dhcp申请ip地址操作
event = EVENT_INTERFACE_CONFIGURATION_SUCCEEDED;
if ( LOCAL_LOGD) Log . v( TAG, "DhcpHandler: DHCP request succeeded" ) ;
} else {
event = EVENT_INTERFACE_CONFIGURATION_FAILED;
Log . i( TAG, "DhcpHandler: DHCP request failed: " +
NetworkUtils. getDhcpError( ) ) ;
//如果dhcpcd分配ip失败,那么Message.obtain(mTarget, event).sendToTarget();将执行
//WifiNative.disconnectCommand();即：static JNINativeMethod gWifiMethods[] = {
//android_net_wifi_disconnectCommand发送"DISCONNECT"字符串[luther.gliethttp]
//然后在wpa_supplicant服务端执行wpa_supplicant_ctrl_iface_process
//wpa_supplicant_disassociate
}
synchronized ( this ) {
WifiNative. setPowerModeCommand( DRIVER_POWER_MODE_AUTO) ;
}
Message. obtain( mTarget, event ) . sendToTarget( ) ;
break ;
}
}
}
. . .
/**
* Send the tracker a notification that a connection to the supplicant
* daemon has been established.
*/
//在上面的public class WifiMonitor=>ensureSupplicantConnection
//=>
//while (!supplicantConnected) {
// boolean connected;
//synchronized (mWifiStateTracker) {
//connected = WifiNative.connectToSupplicant();//如果没有连接成功,那么while循环尝试,直到尝试成功,或者定义了oneShot,仅一次尝试
//=>mWifiStateTracker.notifySupplicantConnection();//如果WifiNative.connectToSupplicant()成功,那么将执行
//mWifiStateTracker.notifySupplicantConnection();的调用.
void notifySupplicantConnection( ) { //向对象发送message
Message. obtain( this , EVENT_SUPPLICANT_CONNECTION) . sendToTarget( ) ;
}
void notifyStateChange( SupplicantState newState) {
Message. obtain( this , EVENT_SUPPLICANT_STATE_CHANGED, newState) . sendToTarget( ) ;
}
. . .
}
static jboolean android_net_wifi_setPowerModeCommand( JNIEnv* env , jobject clazz, jint mode)
{
char cmdstr[ 256] ;

sprintf( cmdstr, "DRIVER POWERMODE %d" , mode) ;
return doBooleanCommand( cmdstr, "OK" ) ;
}
android_net_wifi_setPowerModeCommand
= > doBooleanCommand
= > doCommand
= > wifi_command
= > wifi_send_command
= > wpa_ctrl_request
= > send给wpa_supplicant
然后wpa_supplicant将做如下接收操作：
system / extra/ wpa_supplicant/ main. c
= > wpa_supplicant_add_iface
= > wpa_supplicant_init_iface2
= > wpa_supplicant_ctrl_iface_init
= > 注册ctrl_conn控制端口和monitor_conn监听端口的处理函数
eloop_register_read_sock( priv- > sock, wpa_supplicant_ctrl_iface_receive, wpa_s, priv) ; //ctrl_conn端口的handler处理函数
wpa_msg_register_cb( wpa_supplicant_ctrl_iface_msg_cb) ; //monitor_conn端口的回调处理函数,处理netlink数据到所有monitor_conn监听端口
= > wpa_supplicant_ctrl_iface_receive //对于unix通信方式
= > wpa_supplicant_ctrl_iface_process
= > 如果wpa_cli发送的是wpa_clidriver xxx形式的命令, 那么调用这个函数
if ( os_strncmp( buf, "DRIVER " , 7) = = 0) { //掠过前7个,直接将命令传过去
reply_len= wpa_supplicant_driver_cmd( wpa_s, buf+ 7, reply, reply_size) ;
= > wpa_supplicant_driver_cmd
= > wpa_drv_driver_cmd
= > 自定义DRIVER扩展处理函数, 所以对于java传递过来的power电源管理命令, wpa_drv_driver_cmd将收到"POWERMODE 0" 或者"POWERMODE 1" 字符串[ luther. gliethttp]
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
jni
= > runDhcp
= > android_net_utils_runDhcp
libs/ netutils/ dhcp_utils. c
= > dhcp_do_request
= >
static const char DAEMON_NAME[ ] = "dhcpcd" ;
static const char DAEMON_PROP_NAME[ ] = "init.svc.dhcpcd" ;
static const char DHCP_PROP_NAME_PREFIX[ ] = "dhcp" ;
const char * ctrl_prop= "ctl.start" ;
const char * desired_status= "running" ;
snprintf( result_prop_name, sizeof( result_prop_name) , "%s.%s.result" ,
DHCP_PROP_NAME_PREFIX,
interface ) ;
property_set( result_prop_name, "" ) ; //设置dhcp.eth0.result="";等到成功完成dhcp之后,
property_set( ctrl_prop, DAEMON_NAME) ; //向名字为dhcpcd的service,发送"ctrl.start"启动命令字,该service在init.rc中
//init.rc中dhcpcd服务进程命令字
//service dhcpcd /system/bin/dhcpcd eth0
// disabled
// oneshot
wait_for_property( DAEMON_PROP_NAME, desired_status, 10) ;
//init.c=>init进程
//=>handle_property_set_fd因为是"ctrl.start"命令字,所以调用handle_control_message处理控制信息
//=>handle_control_message
//=>msg_start
//=>
// struct service *svc = service_find_by_name(name);
// service_start(svc);//启动svc,即执行：/system/bin/dhcpcd eth0
//=>service_start
//=>pid = fork();
// if(pid == 0)execve(svc->args[0], (char**) svc->args, (char**) ENV);子进程执行execve运行/system/bin/dhcpcd,参数为eth0
//=>否则父进程,即init进程将
//=>notify_service_state(svc->name, "running");设置该svc的状态prop
// snprintf(pname, sizeof(pname), "init.svc.%s", name);
// property_set(pname, state);//所以这样上面wait_for_property(DAEMON_PROP_NAME, desired_status, 10);也才能够正常pass[luther.gliethttp].
wait_for_property( result_prop_name, NULL , 15) ; //等待dhcp.eth0.result=非空
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
system / extra/ dhcpcd- 4. 0. 0- beta9/ dhcpcd. c
dhcpcd
= > main
# define SYSCONFDIR"/system/etc/dhcpcd"
#definePACKAGE "dhcpcd"
# defineCONFIG SYSCONFDIR"/" PACKAGE ".conf"
# define LIBEXECDIR"/system/etc/dhcpcd"
# define SCRIPTLIBEXECDIR"/" PACKAGE "-run-hooks"
= > strlcpy( options- > script, SCRIPT, sizeof( options- > script) ) ; //默认的options->script="/system/etc/dhcpcd/dhcpcd-run-hooks"
= > f= fopen( cf? cf: CONFIG , "r" ) ; //如果没有指定.conf文件,那么使用默认.conf文件
= > parse_config_line //解析"/system/etc/dhcpcd/dhcpcd.conf"默认配置文件
= > parse_option
= > 如果在"/system/etc/dhcpcd/dhcpcd.conf" 有"script" 这个节
= > 那么执行strlcpy( options- > script, oarg, sizeof( options- > script) ) ; 直接拷贝
/*
{"script", required_argument, NULL, 'c'},
{"option", required_argument, NULL, 'o'},
"/system/etc/dhcpcd/dhcpcd.conf"中的部分内容如下：
...
option domain_name_servers, domain_name, domain_search, host_name
...
*/
= > dhcp_run
= > handle_dhcp_packet
= > handle_dhcp
= > bind_dhcp
reason= "TIMEOUT" ; reason= "BOUND" ; reason= "REBIND" ; reason= "RENEW" ;
system / extra/ dhcpcd- 4. 0. 0- beta9/ configure. c
= > configure( iface, reason, state - > new , state - > old, & state - > lease , options, 1) ;
//如果dhcp超时或者dhcp成功,都会调用exec_script来执行脚本,
//执行setprop dhcp.${interface}.result "failed"或者
//执行setprop dhcp.${interface}.result "ok"
= > exec_script( options, iface- > name , reason, NULL , old) ;
= > 然后configure_env通过环境变量将reason传递到脚本中
int exec_script( const struct options* options, const char * iface, const char * reason,
const struct dhcp_message* dhcpn, const struct dhcp_message* dhcpo)
= > pid= fork( ) ;
= > if ( pid= = 0) execve( options- > script, argv, env ) ; //子进程执行脚本,默认"/system/etc/dhcpcd/dhcpcd-run-hooks"
//dhcpcd-run-hooks脚本会根据level值,决定是否执行system/etc/dhcpcd/dhcpcd-hook/*目录下的相应文件
//我们的系统在该system/etc/dhcpcd/dhcpcd-hook/*目录下有如下3个文件
//95-configured
//20-dns.conf
//01-test
= > 父进程返回while( waitpid( pid, & status , 0) = = - 1) 等待子进程脚本执行完成

system / extra/ dhcpcd- 4. 0. 0- beta9/ dhcpcd- hooks/ 20- dns. conf
system / extra/ dhcpcd- 4. 0. 0- beta9/ dhcpcd- hooks/ 95- configured
. . .
setprop dhcp. $ { interface } . ipaddress"${new_ip_address}"
setprop dhcp. $ { interface } . result "ok" //设置属性为ok
setprop dhcp. $ { interface } . result "failed"
. . .
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
inet_init、tcp_prot
sock- > ops- > sendmsg( iocb, sock, msg, size ) ;
= > inetsw_array[ ]
= > inet_stream_ops
= > tcp_sendmsg
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
wpa_cli. c
= > main
= > wpa_cli_interactive
= > wpa_cli_recv_pending( monitor_conn, 0, 0) ; //阻塞等待wpa_supplicant发送数据过来
= > 如果action_monitor为true, 那么将执行一些简单加工操作, 否则将直接将wpa_supplicant发过来的数据打印到console上[ luther. gliethttp] .
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =