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从Windows 7开始,微软在操作系统中加入的Soft AP功能,使用户能够通过无线网卡,开启虚拟AP,从而实现网络共享。Soft AP又称HostedNetwork(承载网络),在Windows SDK中,提供了相应的API,以WlanHostedNetwork***开头的一系列函数。

 

要编码实现Soft AP,首先需要添加相应的头文件及lib库

1 #include <wlanapi.h>
2 #include <iphlpapi.h>
3 #include <winsock2.h>
4 #pragma comment(lib, "ws2_32.lib")
5 #pragma comment(lib, "Wlanapi.lib")
6 #pragma comment(lib, "IPHLPAPI.lib"

其中,wlanapi.h是无线网络API的声明文件,函数名一般以Wlan开头。iphlpapi.h用于调用GetAdapterInfo函数,获取网络虚拟接口信息。

 

和winsock套接字编程类似,Wlan库使用前需获得句柄,并进行版本协商,只不过都在WlanOpenHandle实现了。使用完句柄后,调用WlanCloseHandle关闭以释放资源。

WlanOpenHandle原形如下:

1 DWORD WINAPI WlanOpenHandle(
2   _In_        DWORD dwClientVersion,
3   _Reserved_  PVOID pReserved,
4   _Out_       PDWORD pdwNegotiatedVersion,
5   _Out_       PHANDLE phClientHandle
6 );

dwClientVersion指定程序期望使用的Wlan版本,使用宏WLAN_API_VERSION代替。从vista开始,版本号为2,xp系统为1。协商后的版本通过参数pdwNegotiatedVersion返回,通过检查主版本号来验证(如下代码所示)。句柄通过phClient返回。

 

 1     DWORD dwError = 0;
 2     DWORD dwServiceVersion = 0;
 3     HANDLE hClient = NULL;
 4 
 5     if (ERROR_SUCCESS != (dwError = WlanOpenHandle(
 6         WLAN_API_VERSION,   
 7         NULL,               // reserved
 8         &dwServiceVersion,
 9         &hClient
10         )))
11     {
12         return -1;
13     }
14 
15     // check service version
16     if (WLAN_API_VERSION_MAJOR(dwServiceVersion) < WLAN_API_VERSION_MAJOR(WLAN_API_VERSION_2_0))
17     {
18         WlanCloseHandle(hClient, NULL);
19     }

 

  

 启动承载网络前,需要将模式配置为allow状态,并设置SSID和密码。可以调用WlanHostedNetworkSetProperty进行设置,WlanHostedNetworkSetProperty原型如下:

1 DWORD WINAPI WlanHostedNetworkSetProperty(
2   _In_        HANDLE hClientHandle,
3   _In_        WLAN_HOSTED_NETWORK_OPCODE OpCode,
4   _In_        DWORD dwDataSize,
5   _In_        PVOID pvData,
6   _Out_opt_   PWLAN_HOSTED_NETWORK_REASON pFailReason,
7   _Reserved_  PVOID pvReserved
8 );

其中hClientHandle是我们之前调用WlanOpenHnadle获得的句柄;dwDataSize指定了pvData缓冲区的大小,而pvData指向的变量类型取决与OpCode的取值。OpCode为WLAN_HOSTED_NETWORK_OPCODE枚举,如果指定为wlan_hosted_network_opcode_enable,那么pvData传入一个BOOL型的变量指针,用于指示承载网络模式为允许还是禁止(allow/disallow);如果OpCode为wlan_hosted_network_opcode_connection_settings,那么pvData指向WLAN_HOSTED_NETWORK_CONNECTION_SETTINGS结构体,指定承载网络的SSID和最大连接数目(peer count).

 

示例代码:

 1     // 设置承载网络模式为允许
 2     BOOL bIsAllow = TRUE;
 3     WLAN_HOSTED_NETWORK_REASON dwFailedReason;
 4     DWORD dwReturnValue = WlanHostedNetworkSetProperty(hWlanClient, 
 5         wlan_hosted_network_opcode_enable, 
 6         sizeof(BOOL), 
 7         &bIsAllow, 
 8         &dwFailedReason, 
 9         NULL);
10 
11     if(ERROR_SUCCESS != dwReturnValue)
12     {
13         return -1;
14     }
15 
16 
17 
18 
19     // 设置承载网络的SSID和最大连接数
20     WLAN_HOSTED_NETWORK_CONNECTION_SETTINGS wlanConnectionSetting;
21     memset(&wlanConnectionSetting, 0, sizeof(WLAN_HOSTED_NETWORK_CONNECTION_SETTINGS));
22 
23     // WLAN_HOSTED_NETWORK_CONNECTION_SETTINGS中的SSID字段必须为ANSI类型,因此如果程序使用的是Unicode,则需要做转换。
24 #ifdef _UNICODE
25     WideCharToMultiByte(CP_ACP,
26         0,
27         strSSID.GetBuffer(0),   // 保存SSID的CString类型
28         strSSID.GetLength(),    // SSID字符串的长度
29         (LPSTR)wlanConnectionSetting.hostedNetworkSSID.ucSSID,
30         32,
31         NULL,
32         NULL);
33 #else
34     memcpy(wlanConnectionSetting.hostedNetworkSSID.ucSSID, strSSID.GetBuffer(0), strlen(strSSID.GetBuffer(0)));
35 #endif   
36 
37     wlanConnectionSetting.hostedNetworkSSID.uSSIDLength = strlen((const char*)wlanConnectionSetting.hostedNetworkSSID.ucSSID);
38     wlanConnectionSetting.dwMaxNumberOfPeers = 100;    
39 
40     dwReturnValue = WlanHostedNetworkSetProperty(m_hWlanClient, 
41         wlan_hosted_network_opcode_connection_settings, 
42         sizeof(WLAN_HOSTED_NETWORK_CONNECTION_SETTINGS), 
43         &wlanConnectionSetting,
44         &dwFailedReason,
45         NULL);
46     if(ERROR_SUCCESS != dwReturnValue)
47     {
48         return -1;
49     }

 

 

调用WlanHostedNetworkSetSecondaryKey函数,设置承载网络的连接密码,函数原型如下:

1 DWORD WINAPI WlanHostedNetworkSetSecondaryKey(
2   _In_        HANDLE hClientHandle,
3   _In_        DWORD dwKeyLength,
4   _In_        PUCHAR pucKeyData,
5   _In_        BOOL bIsPassPhrase,
6   _In_        BOOL bPersistent,
7   _Out_opt_   PWLAN_HOSTED_NETWORK_REASON pFailReason,
8   _Reserved_  PVOID pvReserved
9 );

hClientHandle是我们之前调用WlanOpenHnadle获得的句柄;

bIsPassPhrase表明传入pucKeyData的密码是否为口令格式,如果是口令格式,则是8-63位的ASCII字符串,该参数设置为TRUE;如果为16进制的binary,参数设置为FALSE;

dwKeyLength是密码缓冲区的长度,密码为口令格式时,必须包括结尾的\'\0\'

pucKeyData如果字符串,则必须为ANSI类型,因此如果IDE环境将字符串配置为UNICODE,需要做转换,可使用WideCharToMultiByte,或者T2A,W2A宏。

bPersistent用来指示密码是否是持久的。如果不是,那么该密码只在本次启动有效;否则下次启动Soft AP依然使用本次设置的密码。

 

示例代码:

 1     UCHAR keyBuf[100] = {0};
 2 #ifdef _UNICODE
 3     WideCharToMultiByte(CP_ACP,
 4         0,
 5         strSecondaryKey.GetBuffer(0),
 6         strSecondaryKey.GetLength(),
 7         (LPSTR)keyBuf,
 8         100,
 9         NULL,
10         NULL);
11 #else
12     memcpy(keyBuf, strSecondaryKey.GetBuffer(0), strlen(strSecondaryKey.GetBuffer(0)));
13 #endif
14     dwReturnValue = WlanHostedNetworkSetSecondaryKey(m_hWlanClient,
15         strlen((const char*)keyBuf) + 1,
16         keyBuf,
17         TRUE,
18         FALSE,
19         &dwFailedReason,
20         NULL);
21     if(ERROR_SUCCESS != dwReturnValue)
22     {
23         return -1;
24     }

 

 

启动或者停止Soft AP,需要用到如下四个函数:

 1 DWORD WINAPI WlanHostedNetworkStartUsing(
 2   _In_        HANDLE hClientHandle,
 3   _Out_opt_   PWLAN_HOSTED_NETWORK_REASON pFailReason,
 4   _Reserved_  PVOID pvReserved
 5 );
 6 
 7 
 8 DWORD WINAPI WlanHostedNetworkStopUsing(
 9   _In_        HANDLE hClientHandle,
10   _Out_opt_   PWLAN_HOSTED_NETWORK_REASON pFailReason,
11   _Reserved_  PVOID pvReserved
12 );
13 
14 DWORD WINAPI WlanHostedNetworkForceStart(
15   _In_        HANDLE hClientHandle,
16   _Out_opt_   PWLAN_HOSTED_NETWORK_REASON pFailReason,
17   _Reserved_  PVOID pvReserved
18 );
19 
20 DWORD WINAPI WlanHostedNetworkForceStop(
21   _In_        HANDLE hClientHandle,
22   _Out_opt_   PWLAN_HOSTED_NETWORK_REASON pFailReason,
23   _Reserved_  PVOID pvReserved
24 );

参数的含义很直观,这里不再做更多地解释。值得注意的是,如果用StartUsing或者StopUsing版本的函数时,如果有客户端连接到了AP,调用WlanHostedNetworkStopUsing并不能立即停止Soft AP,而要等到客户端主动断开连接后,Soft AP才会停止。如果调用带Force的函数版本,则会强制停止Soft AP,不管是否有客户端正在连接到该AP上。当然,调用带Force的函数版本需要程序以管理员方式启动。

示例代码:

 1     dwReturnValue = WlanHostedNetworkStartUsing(m_hWlanClient, &dwFailedReason, NULL);    
 2     if(ERROR_SUCCESS != dwReturnValue)
 3     {
 4         if (wlan_hosted_network_reason_interface_unavailable == dwFailedReason)
 5         {
 6             return 0;
 7         }
 8         return -1;
 9     }
10 
11     dwReturnValue = WlanHostedNetworkStopUsing(m_hWlanClient, &dwFailedReason, NULL);
12     if (ERROR_SUCCESS != dwReturnValue)
13     {
14         return -1;
15     }

 

 

启动Soft AP后,绑定Ip需要一定的时间,一般为2-3秒。Ip地址一般为192.168.173.1(也有可能是192.168.137.1). 

 

 

调试程序时,可使用命令行方式使用Soft AP(管理员方式打开cmd):

查看当前承载网络状态 - netsh wlan show hostednetwork 

配置承载网络属性,如SSID,密码等 - netsh wlan set hostednetwork ssid=***** key=***** mode=allow|disallow  (星号部分为ascii字符,key必须在8-63个字符之间)

启动承载网络 - netsh wlan start hostednetwork

关闭承载网络 - netsh wlan stop hostednetwork

 

 

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