VC++玩转Native Wifi API

Windows应用想要实现连接wifi，监听wifi信号，断开连接等功能，用NativeWifi API是个不错的选择。

打开MSDN,搜索NativeWifi Api，找到Native Wifi页。在这里。

信息量很大，如果像我着急实现上述功能，看海量的文档有些来不及。如果直接给我例子，在运行中调试，阅读代码，效率会更高。

但是，我并没有成功。首先，Sample在SDK

中，参见这里。我下载几次都失败了，最后放弃这条路。后来同事给了我一份Sample，我不敢确定是否就是这个，但是代码写的也是很晦涩。我的初衷是简单的使用这些API的例子。

看来还是自己动手吧。看相关API，如果不懂，就找有经验人的例子。

几经周折，终于实现我的需求。让我慢慢道来。

1.获得可用AP列表

参见WlanGetAvailableNetworkList的官方文档，下面有例子。

DWORD WINAPI WlanGetAvailableNetworkList(_In_        HANDLE hClientHandle,_In_        const GUID *pInterfaceGuid,_In_        DWORD dwFlags,_Reserved_  PVOID pReserved,_Out_       PWLAN_AVAILABLE_NETWORK_LIST *ppAvailableNetworkList
);

由可用列表便可以找到当前哪个AP正在连接，并显示信号强度。

2.监听当前连接

在获得可用AP列表的基础上，遍历当前AP，看谁正在连接，并取得它的信号。代码片段如下：

bool isConnect = false;
int numberOfItems = pWLAN_AVAILABLE_NETWORK_LIST->dwNumberOfItems;for(int i = 0; i <= numberOfItems; i++){WLAN_AVAILABLE_NETWORK wlanAN = pWLAN_AVAILABLE_NETWORK_LIST->Network[i];if(wlanAN.dwFlags & WLAN_AVAILABLE_NETWORK_CONNECTED){Wprintf(WLAN signal is %s:%d\n",  wlanAN.strProfileName, wlanAN.wlanSignalQuality);isConnect = true;              }}if(!isConnect){            wprintf("Wifi is disconnected!\n");}

3.断开连接

如果wifi处于连接状态，将其断开。WlanDisconnect还是容易使用的。原型如下：

DWORD WINAPI WlanDisconnect(_In_        HANDLE hClientHandle,_In_        const GUID *pInterfaceGuid,_Reserved_  PVOID pReserved
);

代码演示在后面。

4.连接一个有profile的AP（已保存过密码）

这是本文的重点。
虽然连接函数WlanConnect原型很简单：

DWORD WINAPI WlanConnect(_In_        HANDLE hClientHandle,_In_        const GUID *pInterfaceGuid,_In_        const PWLAN_CONNECTION_PARAMETERS pConnectionParameters,_Reserved_  PVOID pReserved
);

但参数PWLAN_CONNECTION_PARAMETERS却是很复杂，只要有一个配错，连接就会失败。
还好我的需求还是蛮简单的，只要连接已有的profile的AP。那么我的工作就会有针对性的开展。挫折了好多天，每次都连接失败，原因是ERROR_INVALID_PARAMETER。
就在今天，我终于成功了。真是会者不难，难者不会啊。
看看连接参数的结构体：

typedef struct _WLAN_CONNECTION_PARAMETERS {WLAN_CONNECTION_MODE wlanConnectionMode;LPCWSTR              strProfile;PDOT11_SSID          pDot11Ssid;PDOT11_BSSID_LIST    pDesiredBssidList;DOT11_BSS_TYPE       dot11BssType;DWORD                dwFlags;
} WLAN_CONNECTION_PARAMETERS, *PWLAN_CONNECTION_PARAMETERS;

为了实现我的要求，可以这样赋值：
wlanConnectionMode这里设成wlan_connection_mode_profile
strProfile写上你要连接ap的名称（通常是profile名称）
pDot11Ssid用不上，设置NULL
pDesiredBssidList同样置成NULL
dot11BssType我给设成dot11_BSS_type_infrastructure（基础设施？）
dwFlags设置为WLAN_CONNECTION_HIDDEN_NETWORK
确实是工作了，strProfile如何获取呢？参见监听连接信号中对可用AP列表中第一个profile的获取。
完整代码如下：

//
#include "stdafx.h"
#include <windows.h>
#include <wlanapi.h>
#include <objbase.h>
#include <wtypes.h>
#include <string>
#include <stdio.h>
#include <stdlib.h>// Need to link with Wlanapi.lib and Ole32.lib
#pragma comment(lib, "wlanapi.lib")
#pragma comment(lib, "ole32.lib")using namespace std;int listenStatus()
{HANDLE hClient = NULL;DWORD dwMaxClient = 2;       DWORD dwCurVersion = 0;DWORD dwResult = 0;DWORD dwRetVal = 0;int iRet = 0;WCHAR GuidString[39] = {0};//Listen the status of the AP you connected.while(1){Sleep(5000);PWLAN_INTERFACE_INFO_LIST pIfList = NULL;//I think wlan interface means network cardPWLAN_INTERFACE_INFO pIfInfo = NULL;DWORD dwFlags = 0;       dwResult = WlanOpenHandle(dwMaxClient, NULL, &dwCurVersion, &hClient);if (dwResult != ERROR_SUCCESS) {wprintf(L"WlanOpenHandle failed with error: %u\n", dwResult);return 1;}dwResult = WlanEnumInterfaces(hClient, NULL, &pIfList);if (dwResult != ERROR_SUCCESS) {wprintf(L"WlanEnumInterfaces failed with error: %u\n", dwResult);return 1;} else {wprintf(L"WLAN_INTERFACE_INFO_LIST for this system\n");wprintf(L"Num Entries: %lu\n", pIfList->dwNumberOfItems);wprintf(L"Current Index: %lu\n\n", pIfList->dwIndex);int i;for (i = 0; i < (int) pIfList->dwNumberOfItems; i++) {pIfInfo = (WLAN_INTERFACE_INFO *) &pIfList->InterfaceInfo[i];wprintf(L"  Interface Index[%u]:\t %lu\n", i, i);iRet = StringFromGUID2(pIfInfo->InterfaceGuid, (LPOLESTR) &GuidString, sizeof(GuidString)/sizeof(*GuidString)); if (iRet == 0)wprintf(L"StringFromGUID2 failed\n");else {wprintf(L"  InterfaceGUID[%d]: %ws\n",i, GuidString);}    wprintf(L"  Interface Description[%d]: %ws", i, pIfInfo->strInterfaceDescription);wprintf(L"\n");wprintf(L"  Interface State[%d]:\t ", i);switch (pIfInfo->isState) {case wlan_interface_state_not_ready:wprintf(L"Not ready\n");break;case wlan_interface_state_connected:wprintf(L"Connected\n");break;case wlan_interface_state_ad_hoc_network_formed:wprintf(L"First node in a ad hoc network\n");break;case wlan_interface_state_disconnecting:wprintf(L"Disconnecting\n");break;case wlan_interface_state_disconnected:wprintf(L"Not connected\n");break;case wlan_interface_state_associating:wprintf(L"Attempting to associate with a network\n");break;case wlan_interface_state_discovering:wprintf(L"Auto configuration is discovering settings for the network\n");break;case wlan_interface_state_authenticating:wprintf(L"In process of authenticating\n");break;default:wprintf(L"Unknown state %ld\n", pIfInfo->isState);break;}}}}
}int _tmain(int argc, _TCHAR* argv[])
{HANDLE hClient = NULL;DWORD dwMaxClient = 2;       DWORD dwCurVersion = 0;DWORD dwResult = 0;DWORD dwRetVal = 0;int iRet = 0;    /* variables used for WlanEnumInterfaces  */PWLAN_INTERFACE_INFO_LIST pIfList = NULL;PWLAN_INTERFACE_INFO pIfInfo = NULL;LPCWSTR pProfileName = NULL;LPWSTR pProfileXml = NULL;DWORD dwFlags = 0;pProfileName = argv[1];wprintf(L"Information for profile: %ws\n\n", pProfileName);dwResult = WlanOpenHandle(dwMaxClient, NULL, &dwCurVersion, &hClient);if (dwResult != ERROR_SUCCESS) {wprintf(L"WlanOpenHandle failed with error: %u\n", dwResult);return 1;}dwResult = WlanEnumInterfaces(hClient, NULL, &pIfList);if (dwResult != ERROR_SUCCESS) {wprintf(L"WlanEnumInterfaces failed with error: %u\n", dwResult);return 1;} else {dwResult = WlanDisconnect(hClient, &pIfList->InterfaceInfo[0].InterfaceGuid,NULL);//DISCONNECT FIRSTif(dwResult != ERROR_SUCCESS){printf("WlanDisconnect failed with error: %u\n",dwResult);return -1;}PWLAN_AVAILABLE_NETWORK_LIST pWLAN_AVAILABLE_NETWORK_LIST = NULL;dwResult = WlanGetAvailableNetworkList(hClient, &pIfList->InterfaceInfo[0].InterfaceGuid,WLAN_AVAILABLE_NETWORK_INCLUDE_ALL_MANUAL_HIDDEN_PROFILES,NULL, &pWLAN_AVAILABLE_NETWORK_LIST);if (dwResult != ERROR_SUCCESS){            printf("WlanGetAvailableNetworkList failed with error: %u\n",dwResult);WlanFreeMemory(pWLAN_AVAILABLE_NETWORK_LIST);return -1;}WLAN_AVAILABLE_NETWORK wlanAN = pWLAN_AVAILABLE_NETWORK_LIST->Network[0];//PLEASE CHECK THIS YOURSELFif(pProfileName == NULL)pProfileName = wlanAN.strProfileName;   WLAN_CONNECTION_PARAMETERS wlanConnPara;wlanConnPara.wlanConnectionMode =wlan_connection_mode_profile ; //YES,WE CONNECT AP VIA THE PROFILEwlanConnPara.strProfile =pProfileName;                           // set the profile namewlanConnPara.pDot11Ssid = NULL;                                 // SET SSID NULLwlanConnPara.dot11BssType = dot11_BSS_type_infrastructure;     //dot11_BSS_type_any,I do not need it this time.        wlanConnPara.pDesiredBssidList = NULL;                         // the desired BSSID list is emptywlanConnPara.dwFlags = WLAN_CONNECTION_HIDDEN_NETWORK;           //it works on my WIN7\8dwResult=WlanConnect(hClient,&pIfList->InterfaceInfo[0].InterfaceGuid,&wlanConnPara ,NULL);if (dwResult==ERROR_SUCCESS){printf("WlanConnect success!\n");}else{printf("WlanConnect failed err is %d\n",dwResult);}}listenStatus(); //LISTEN THE STATUSif (pProfileXml != NULL) {WlanFreeMemory(pProfileXml);pProfileXml = NULL;}if (pIfList != NULL) {WlanFreeMemory(pIfList);pIfList = NULL;}return dwRetVal;
}

5.打开网络设置界面

遇到以前没有连接过的AP，需要输入密码，那么，直接打开配置界面让用户自己来搞吧。

    ShellExecute(NULL, L"open", L"shell:::{21EC2020-3AEA-1069-A2DD-08002B30309D}\\::{38a98528-6cbf-4ca9-8dc0-b1e1d10f7b1b}",NULL,NULL,SW_SHOWNORMAL);

6.最后

当屏幕上打印出“WlanConnect success!”的时候，别提多高兴了。

就像爱迪生试验灯丝一下，在无数次失败后，终于找到了一种材料可以胜任灯丝的工作。这种喜悦真的令人振奋，往日的阴霾和不爽终于一扫而光。
其实我也尝试过WlanGetProfile和WlanSetProfile，虽然有时结果是能够连上指定AP，但是函数返回结果却总是ERROR_INVALID_PARAMETER。
网上的例子，很多都是抄来抄去的，写的不明不白，虽然有过帮助，但是也有些误导。
今天自己成功的连接到指定AP了（用命令行运行我的例子，输入参数profile name），我一定要把它发表出来，让其他人有个参考。
我认为这是一件诚意的作品，在此也谢谢给过我帮助的朋友。
最后说一下获得的信号。标准信号RSSI是负值，而这里获得的信号都是正值（0~100），在有些需要RSSI的地方，我们需要转换一下：

                   if (pBssEntry->wlanSignalQuality == 0)iRSSI = -100;else if (pBssEntry->wlanSignalQuality == 100)   iRSSI = -50;elseiRSSI = -100 + (pBssEntry->wlanSignalQuality/2);    wprintf(L"  Signal Quality[%u]:\t %u (RSSI: %i dBm)\n", j, pBssEntry->wlanSignalQuality, iRSSI);

本文到此完毕，虽然没有涵盖大部分API，但还是欢迎大家留意讨论。