C++程序中使用Windows系統(tǒng)Native Wifi API的基本教程
Windows應(yīng)用想要實(shí)現(xiàn)連接wifi,監(jiān)聽wifi信號,斷開連接等功能,用NativeWifi API是個(gè)不錯(cuò)的選擇。
打開MSDN,搜索NativeWifi Api,找到Native Wifi頁。在這里。
信息量很大,如果像我著急實(shí)現(xiàn)上述功能,看海量的文檔有些來不及。如果直接給我例子,在運(yùn)行中調(diào)試,閱讀代碼,效率會(huì)更高。
但是,我并沒有成功。首先,Sample在SDK中,參見這里。我下載幾次都失敗了,最后放棄這條路。后來同事給了我一份Sample,我不敢確定是否就是這個(gè),但是代碼寫的也是很晦澀。我的初衷是簡單的使用這些API的例子。
看來還是自己動(dòng)手吧??聪嚓P(guān)API,如果不懂,就找有經(jīng)驗(yàn)人的例子。
幾經(jīng)周折,終于實(shí)現(xiàn)我的需求。讓我慢慢道來。
1.獲得可用AP列表
參見WlanGetAvailableNetworkList的官方文檔,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當(dāng)前哪個(gè)AP正在連接,并顯示信號強(qiáng)度。
2.監(jiān)聽當(dāng)前連接
在獲得可用AP列表的基礎(chǔ)上,遍歷當(dāng)前AP,看誰正在連接,并取得它的信號。代碼片段如下:
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.斷開連接
如果wifi處于連接狀態(tài),將其斷開。WlanDisconnect還是容易使用的。原型如下:
DWORD WINAPI WlanDisconnect( _In_ HANDLE hClientHandle, _In_ const GUID *pInterfaceGuid, _Reserved_ PVOID pReserved );
代碼演示在后面。
4.連接一個(gè)有profile的AP(已保存過密碼)
這是本文的重點(diǎn)。
雖然連接函數(shù)WlanConnect原型很簡單:
DWORD WINAPI WlanConnect( _In_ HANDLE hClientHandle, _In_ const GUID *pInterfaceGuid, _In_ const PWLAN_CONNECTION_PARAMETERS pConnectionParameters, _Reserved_ PVOID pReserved );
還好我的需求還是蠻簡單的,只要連接已有的profile的AP。那么我的工作就會(huì)有針對性的開展。挫折了好多天,每次都連接失敗,原因是ERROR_INVALID_PARAMETER。
就在今天,我終于成功了。真是會(huì)者不難,難者不會(huì)啊。
看看連接參數(shù)的結(jié)構(gòu)體:
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;
為了實(shí)現(xiàn)我的要求,可以這樣賦值:
wlanConnectionMode這里設(shè)成wlan_connection_mode_profile;
strProfile寫上你要連接ap的名稱(通常是profile名稱);
pDot11Ssid用不上,設(shè)置NULL;
pDesiredBssidList同樣置成NULL;
dot11BssType我給設(shè)成dot11_BSS_type_infrastructure(基礎(chǔ)設(shè)施?);
dwFlags設(shè)置為WLAN_CONNECTION_HIDDEN_NETWORK。
確實(shí)是工作了,strProfile如何獲取呢?參見監(jiān)聽連接信號中對可用AP列表中第一個(gè)profile的獲取。
完整代碼如下:
// #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 card PWLAN_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 FIRST if(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 YOURSELF if(pProfileName == NULL) pProfileName = wlanAN.strProfileName; WLAN_CONNECTION_PARAMETERS wlanConnPara; wlanConnPara.wlanConnectionMode =wlan_connection_mode_profile ; //YES,WE CONNECT AP VIA THE PROFILE wlanConnPara.strProfile =pProfileName; // set the profile name wlanConnPara.pDot11Ssid = NULL; // SET SSID NULL wlanConnPara.dot11BssType = dot11_BSS_type_infrastructure; //dot11_BSS_type_any,I do not need it this time. wlanConnPara.pDesiredBssidList = NULL; // the desired BSSID list is empty wlanConnPara.dwFlags = WLAN_CONNECTION_HIDDEN_NETWORK; //it works on my WIN7\8 dwResult=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 STATUS if (pProfileXml != NULL) { WlanFreeMemory(pProfileXml); pProfileXml = NULL; } if (pIfList != NULL) { WlanFreeMemory(pIfList); pIfList = NULL; } return dwRetVal; }
5.打開網(wǎng)絡(luò)設(shè)置界面
遇到以前沒有連接過的AP,需要輸入密碼,那么,直接打開配置界面讓用戶自己來搞吧。
ShellExecute( NULL, L"open", L"shell:::{21EC2020-3AEA-1069-A2DD-08002B30309D}\\::{38a98528-6cbf-4ca9-8dc0-b1e1d10f7b1b}", NULL, NULL, SW_SHOWNORMAL);
6.RSSI
當(dāng)屏幕上打印出“WlanConnect success!”的時(shí)候,別提多高興了。
就像愛迪生試驗(yàn)燈絲一下,在無數(shù)次失敗后,終于找到了一種材料可以勝任燈絲的工作。這種喜悅真的令人振奮,往日的陰霾和不爽終于一掃而光。
其實(shí)我也嘗試過WlanGetProfile和WlanSetProfile,雖然有時(shí)結(jié)果是能夠連上指定AP,但是函數(shù)返回結(jié)果卻總是ERROR_INVALID_PARAMETER。
網(wǎng)上的例子,很多都是抄來抄去的,寫的不明不白,雖然有過幫助,但是也有些誤導(dǎo)。
今天自己成功的連接到指定AP了(用命令行運(yùn)行我的例子,輸入?yún)?shù)profile name),我一定要把它發(fā)表出來,讓其他人有個(gè)參考。
我認(rèn)為這是一件誠意的作品,在此也謝謝給過我?guī)椭呐笥选?br />
最后說一下獲得的信號。標(biāo)準(zhǔn)信號RSSI是負(fù)值,而這里獲得的信號都是正值(0~100),在有些需要RSSI的地方,我們需要轉(zhuǎn)換一下:
if (pBssEntry->wlanSignalQuality == 0) iRSSI = -100; else if (pBssEntry->wlanSignalQuality == 100) iRSSI = -50; else iRSSI = -100 + (pBssEntry->wlanSignalQuality/2); wprintf(L" Signal Quality[%u]:\t %u (RSSI: %i dBm)\n", j, pBssEntry->wlanSignalQuality, iRSSI);
7.Wifi on與wifi off
下面要說的是在軟件層面控制無線網(wǎng)卡的開和關(guān)。
問題聽起來簡單,調(diào)查起來復(fù)雜,但解決起來卻也簡單。關(guān)鍵函數(shù)便是Native wifi api中的WlanSetInterface。其實(shí)這個(gè)API功能也是非
常強(qiáng)大的,我只用到其中控制wifi radio state的功能。官網(wǎng)文檔在此。
函數(shù)原型:
DWORD WINAPI WlanSetInterface( _In_ HANDLE hClientHandle, _In_ const GUID *pInterfaceGuid, _In_ WLAN_INTF_OPCODE OpCode, _In_ DWORD dwDataSize, _In_ const PVOID pData, _Reserved_ PVOID pReserved );
重點(diǎn)說一下三個(gè)參數(shù):
(1) OpCode,指定要設(shè)置的參數(shù)。我們選擇wlan_intf_opcode_radio_state
(2) DwDataSize,pData的size。傳入時(shí)用sizeof得到。
(3) pData,radio state對應(yīng)的data是WLAN_PHY_RADIO_STATE。
看看這個(gè)state結(jié)構(gòu)體:
typedef struct _WLAN_PHY_RADIO_STATE { DWORD dwPhyIndex; DOT11_RADIO_STATE dot11SoftwareRadioState; DOT11_RADIO_STATE dot11HardwareRadioState; } WLAN_PHY_RADIO_STATE, *PWLAN_PHY_RADIO_STATE;
Index設(shè)為0.
State設(shè)置如下:
typedef enum _DOT11_RADIO_STATE { dot11_radio_state_unknown, dot11_radio_state_on, dot11_radio_state_off } DOT11_RADIO_STATE, *PDOT11_RADIO_STATE;
與前幾個(gè)API(比如wlanconnect)相比,這個(gè)函數(shù)的使用簡單多了。全部源碼如下:
// ManageWirelessNetwork.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <stdio.h> #include <windows.h> #include <shellapi.h> #include <wlanapi.h> // Need to link with shell32.lib #pragma comment(lib, "shell32.lib") #pragma comment(lib, "wlanapi.lib") int _tmain(int argc, _TCHAR* argv[]) { DWORD dwResult = 0; DWORD dwMaxClient = 2; DWORD dwCurVersion = 0; HANDLE hClient = NULL; PWLAN_INTERFACE_INFO_LIST pIfList = NULL; PWLAN_INTERFACE_INFO pIfInfo = NULL; dwResult = WlanOpenHandle(dwMaxClient, NULL, &dwCurVersion, &hClient); if (dwResult != ERROR_SUCCESS) { wprintf(L"WlanOpenHandle failed with error: %u\n", dwResult); return false; } dwResult = WlanEnumInterfaces(hClient, NULL, &pIfList); if (dwResult != ERROR_SUCCESS) { wprintf(L"WlanEnumInterfaces failed with error: %u\n", dwResult); return false; } WLAN_PHY_RADIO_STATE state; state.dwPhyIndex = 0; state.dot11SoftwareRadioState = dot11_radio_state_on; PVOID pData = &state; dwResult = WlanSetInterface(hClient,&pIfList->InterfaceInfo[0].InterfaceGuid, wlan_intf_opcode_radio_state,sizeof(WLAN_PHY_RADIO_STATE),pData,NULL); if(dwResult == ERROR_SUCCESS) { wprintf(L"set state success!\n"); } else { wprintf(L"set state failed!err is %d\n",dwResult); } return 0; }
8.GOTO在釋放資源時(shí)的作用
GOTO語句有著很臭的名聲,我們的老師經(jīng)常教導(dǎo)我們說,不要輕易使用它。
C++跳轉(zhuǎn)語句有三個(gè):goto、break和continue。它們只是工具,我覺得問題不能歸咎于工具,問題在于人。
就像指針一樣,goto這個(gè)無條件跳轉(zhuǎn)語句力量還是很強(qiáng)大的,如果濫用,出現(xiàn)問題很難排查。
但有些時(shí)候goto確實(shí)是不二選擇,例如我遇到的,在函數(shù)中有多個(gè)出口,而每個(gè)出口都遇到釋放資源的時(shí)候,與其都把釋放語句不厭其煩的寫一遍,
不如一個(gè)goto語句來的干脆利落。
下面的例子取自上一篇Native Wifi API文章,由于我們的程序經(jīng)??刂频膚ifi的on和off,必須注意釋放資源。就拿WlanOpenHandle來說,
如果不注意對稱WlanCloseHandler,程序幾次運(yùn)行后報(bào)錯(cuò):ERROR_REMOTE_SESSION_LIMIT_EXCEEDED
官網(wǎng)解釋為:Too many handles have been issued by the server.
所以我們會(huì)在每個(gè)API調(diào)用后,確認(rèn)返回值,如果錯(cuò)誤,程序?qū)⒉辉倮^續(xù)向下運(yùn)行,return之前,我們必須釋放資源。當(dāng)出口很多時(shí),我們要寫很多同樣的代碼,
很煩躁,難讀,代碼急速膨脹。但使用goto后,問題便輕松了許多,請看簡單例子:
// ManageWirelessNetwork.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <stdio.h> #include <windows.h> #include <shellapi.h> #include <wlanapi.h> // Need to link with shell32.lib #pragma comment(lib, "shell32.lib") #pragma comment(lib, "wlanapi.lib") int _tmain(int argc, _TCHAR* argv[]) { DWORD dwResult = 0; DWORD dwMaxClient = 2; DWORD dwCurVersion = 0; HANDLE hClient = NULL; PWLAN_INTERFACE_INFO_LIST pIfList = NULL; PWLAN_INTERFACE_INFO pIfInfo = NULL; dwResult = WlanOpenHandle(dwMaxClient, NULL, &dwCurVersion, &hClient); if (dwResult != ERROR_SUCCESS) { wprintf(L"WlanOpenHandle failed with error: %u\n", dwResult); return false; } dwResult = WlanEnumInterfaces(hClient, NULL, &pIfList); if (dwResult != ERROR_SUCCESS) { wprintf(L"WlanEnumInterfaces failed with error: %u\n", dwResult); goto RELEASE_RESOURCE; } WLAN_PHY_RADIO_STATE state; state.dwPhyIndex = 0; state.dot11SoftwareRadioState = dot11_radio_state_on;//off here too. PVOID pData = &state; dwResult = WlanSetInterface(hClient,&pIfList->InterfaceInfo[0].InterfaceGuid, wlan_intf_opcode_radio_state,sizeof(WLAN_PHY_RADIO_STATE),pData,NULL); if(dwResult == ERROR_SUCCESS) { wprintf(L"set state success!\n"); } else { wprintf(L"set state failed!err is %d\n",dwResult); } RELEASE_RESOURCE: if(hClient) { WlanCloseHandle(hClient,NULL); hClient = NULL; } if(pIfList) { WlanFreeMemory(pIfList); pIfList = NULL; } if(pIfInfo) { WlanFreeMemory(pIfInfo); pIfInfo = NULL; } return 0; }
最后,goto還會(huì)用來跳出多重循環(huán)。但需要注意的是,只能從內(nèi)層跳到外層,不可逆操作。
后記:
其實(shí)幾個(gè)月前就要實(shí)現(xiàn)windows上的wifi on和off,問了許多人,發(fā)了許多帖子,最后都不了了之。之后的日子里也發(fā)生了許多事。國內(nèi)的
搜索無果,加上google的無法使用,都對調(diào)查增加了些許難度。我們把重點(diǎn)先放到了native wifi api的幾個(gè)方法,見上一篇玩轉(zhuǎn)文章。但
那并不是我想要的。
原以為windows也會(huì)想android一樣,普通應(yīng)用沒有權(quán)限來控制wifi的開關(guān)呢,結(jié)果并不是這樣。這也宣告了之前我的判斷失誤。
直到今天,通過Bing發(fā)現(xiàn)了幾條線索。那是通過C#調(diào)用native wifi api的問題,里面提及了之前并沒有重視的wlansetinterface。
Interface,在這里我覺得可以理解成無線網(wǎng)卡。類似的WlanEnumInterfaces中實(shí)現(xiàn)的功能是羅列出當(dāng)前無線網(wǎng)卡。
無線網(wǎng)卡的設(shè)置,其中有一項(xiàng)是radio的狀態(tài)。
果然,這一切都有了了斷。
上一篇:解析C++編程中如何使用設(shè)計(jì)模式中的狀態(tài)模式結(jié)構(gòu)
欄 目:C語言
下一篇:實(shí)例講解C++設(shè)計(jì)模式編程中State狀態(tài)模式的運(yùn)用場景
本文標(biāo)題:C++程序中使用Windows系統(tǒng)Native Wifi API的基本教程
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