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
)

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=

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
MonitorThread extends
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
WifiStateTracker extends
NetworkStateTracker {

.
.
.

public
void
startEventLoop(
)
{

mWifiMonitor.
startMonitoring(
)
;
//启动上面的MonitorThread线程

}

.
.
.

}

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

public
class
WifiService extends
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
WifiStateTracker extends
NetworkStateTracker {

.
.
.

public
void
handleMessage(
Message msg)
{

switch
(
msg.
what)
{

case
EVENT_SUPPLICANT_CONNECTION:

case
EVENT_NETWORK_STATE_CHANGED:

handleConnectedState(
)
;
//调用

.
.
.

private
class
DhcpHandler extends
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_cli driver
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]

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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

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system
/
extra/
dhcpcd-
4.
0.
0-
beta9/
dhcpcd.
c

dhcpcd

=
>
main

# define SYSCONFDIR "/system/etc/dhcpcd"

#define PACKAGE
"dhcpcd"

# define CONFIG
SYSCONFDIR "/"
PACKAGE
".conf"

# define LIBEXECDIR "/system/etc/dhcpcd"

# define SCRIPT LIBEXECDIR "/"
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"

.
.
.

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inet_init、tcp_prot

sock-
>
ops-
>
sendmsg(
iocb,
sock,
msg,
size
)
;

=
>
inetsw_array[
]

=
>
inet_stream_ops

=
>
tcp_sendmsg

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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]
.

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