我通过调用 WlanGetNetworkBssList 陷入调试工作中，希望得到一些指点。我的最终目标是构建一个 Wifi 扫描器/分析器工具来帮助我解决远程站点上的网络问题。
我正在使用 Windows 10 (VCL) 下的 Delphi Berlin 10.1 Update 2 使用 Windows Native Wifi API (链接)和Delphi/Pascal 接口。
我从一个简单粗暴的测试应用程序 (VCL) 开始，以了解 API 并遇到了调用WlanGetNetworkBssList的问题，因此我创建了一个专注于该问题的小型控制台应用程序。问题是它适用于在命令提示符下运行的控制台应用程序，但不适用于我的 VCL 测试应用程序。这些函数几乎是复制粘贴等效的，并且并排执行代码表明数据是相同的，除了来自 WlanGetNetworkBssList 调用 (pWlanBssList) 的返回数据
问题：由于调用的是外部 DLL，我可以采取哪些步骤来进一步调试并了解 VCL 和控制台应用程序之间的区别。
注意：WlanGetNetworkBssList 有两种操作模式，其中可以提供 SSID 来获取特定 SSID 的 BSSID（接入点的 MAC）。通过传递 NULL 而不是 SSID，API 将返回所有 AP 的 BSSID。传递 NULL 适用于 VLC 和控制台应用程序。当请求特定的 SSID 时会中断。经验证，两个应用的SSID数据结构相同，但返回的数据缓冲区对VCL应用无效。怎么会这样？
控制台应用程序：
program CWifiScan;
{$APPTYPE CONSOLE}
uses
Windows,
System.SysUtils,
nduWlanAPI,
nduWlanTypes;
const
WLAN_AVAILABLE_NETWORK_INCLUDE_ALL_ADHOC_PROFILES = $00000001;
var
hWlan: THandle;
guid : TGUID;
dwSupportedVersion: DWORD = 0;
dwClientVersion: DWORD = 1;
i,j : integer;
pInterfaceInfo : Pndu_WLAN_INTERFACE_INFO;
pInterfaceList : Pndu_WLAN_INTERFACE_INFO_LIST;
pAvailableNetworkList : Pndu_WLAN_AVAILABLE_NETWORK_LIST;
procedure GetBSSIDList(clientHandle : THandle;
interfaceGUID : TGUID;
pSSID : Pndu_DOT11_SSID = nil;
SSID_Type : Tndu_DOT11_BSS_Type = dot11_BSS_type_any;
SecurityEnabled : BOOL = True);
var
//to check if interface is connected
pData : Pndu_WLAN_INTERFACE_STATE;
pdwDataSize : DWORD;
isConnected : Boolean;
//to get list of BSSids from available APs
pWlanBssList : Pndu_WLAN_BSS_LIST;
items : integer;
itemIndex : integer;
SSID : string;
MAC : string;
begin
//check if interface is connected
isConnected := False;
if WlanQueryInterface(clientHandle,
@interfaceGUID,
wlan_intf_opcode_interface_state,
nil,
@pdwDataSize,
@pData,
nil) = ERROR_SUCCESS then
begin
isConnected := (pData^ = Tndu_WLAN_INTERFACE_STATE.wlan_interface_state_connected);
end;
//get the list of BSSids for the provided interface
if isConnected then
begin
if WlanGetNetworkBssList(clientHandle,
@interfaceGUID,
pSSID,
SSID_Type,
SecurityEnabled,
nil,
@pWlanBssList) = ERROR_SUCCESS then
begin
items := pWlanBssList^.dwNumberOfItems;
for itemIndex := 0 to items - 1 do
begin
SSID := String(PAnsiChar(@pWlanBssList^.wlanBssEntries[itemIndex].dot11Ssid.ucSSID));
MAC := Format('%.2x:%.2x:%.2x:%.2x:%.2x:%.2x', [
pWlanBssList^.wlanBssEntries[itemIndex].dot11Bssid[0],
pWlanBssList^.wlanBssEntries[itemIndex].dot11Bssid[1],
pWlanBssList^.wlanBssEntries[itemIndex].dot11Bssid[2],
pWlanBssList^.wlanBssEntries[itemIndex].dot11Bssid[3],
pWlanBssList^.wlanBssEntries[itemIndex].dot11Bssid[4],
pWlanBssList^.wlanBssEntries[itemIndex].dot11Bssid[5]]);
Writeln('');
Writeln('SSID: ................ '+SSID);
Writeln('Physical Address: .... '+MAC);
end; {for itemIndex}
Writeln(#10+#13+'Done.');
end; {WlanGetNetworkBssList succeeds}
end; {isConnected}
end;
begin
hWlan := 0;
if WlanOpenHandle(2, nil,@dwSupportedVersion, @hWlan)= ERROR_SUCCESS then
begin
if WlanEnumInterfaces(hWlan, nil, @pInterfaceList) = ERROR_SUCCESS then
begin
try
for i := 0 to pInterfaceList^.dwNumberOfItems-1 do
begin
Writeln('Wifi Adapter - '+GUIDToString( pInterfaceList^.InterfaceInfo[i].InterfaceGuid ) );
Writeln('Scanning: .... '+pInterfaceList^.InterfaceInfo[i].strInterfaceDescription);
guid := pInterfaceList^.InterfaceInfo[i].InterfaceGuid;
//Get all BSSids for this interface
GetBSSIDList(hWlan, guid);
if WlanGetAvailableNetworkList(hWlan,
@guid,
WLAN_AVAILABLE_NETWORK_INCLUDE_ALL_ADHOC_PROFILES,
nil,
pAvailableNetworkList) = ERROR_SUCCESS then
begin
try
for j := 0 to pAvailableNetworkList^.dwNumberOfItems - 1 do
begin
//Get BSSid for this specific SSID
GetBSSIDList(hWlan,
guid,
@pAvailableNetworkList^.Network[j].dot11Ssid,
pAvailableNetworkList^.Network[j].dot11BssType,
pAvailableNetworkList^.Network[j].bSecurityEnabled);
end;
finally
if pAvailableNetworkList<>nil then
WlanFreeMemory(pAvailableNetworkList);
end;
end;
end;
finally
if pInterfaceList<>nil then
WlanFreeMemory(pInterfaceList);
end;
end;
WlanCloseHandle(hWlan, nil);
readln;
end;
end.
VCL 应用程序的相关部分是：
uses
... nduWlanAPI, nduWlanTypes, nduWinDot11;
function TForm1.GetBSSID(clientHandle: THandle;
interfaceGuid: TGUID;
pSSID: Pndu_DOT11_SSID = nil;
SSID_Type : Tndu_DOT11_BSS_TYPE = dot11_BSS_type_any;
SecurityEnabled: boolean = true): string;
var
//used to determin if the interface is connected
pData : Pndu_WLAN_INTERFACE_STATE;
isConnected : boolean;
//used to extract a list of BSSIDs for a given interface
pWlanBssList : Pndu_WLAN_BSS_LIST;
lastError : DWORD;
pdwDataSize : DWORD;
items,
itemIndex: Integer;
begin
pData := nil;
pdwDataSize := 0;
isConnected := False;
//check if the interface is connected
lastError := WlanQueryInterface(clientHandle,
@interfaceGuid,
wlan_intf_opcode_interface_state,
nil,
@pdwDataSize,
@pData,
nil);
if (lastError = ERROR_SUCCESS) then
begin
//isConnected := (Tndu_WLAN_INTERFACE_STATE(pData^.isState) = Tndu_WLAN_INTERFACE_STATE.wlan_interface_state_connected);
isConnected := (pData^ = Tndu_WLAN_INTERFACE_STATE.wlan_interface_state_connected);
end
else
DisplayError('Error in WlanQueryInterface() function', lastError);
if isConnected then
begin
pWlanBssList := nil;
lastError := WlanGetNetworkBssList(clientHandle,
@interfaceGuid,
pSSID,
SSID_Type,
SecurityEnabled,
nil,
@pWlanBssList);
try
if (lastError = ERROR_SUCCESS) then
begin
items := pWlanBssList^.dwNumberOfItems;
for itemIndex := 0 to items-1 do
begin
Result := (Format('%.2x:%.2x:%.2x:%.2x:%.2x:%.2x', [
pWlanBssList^.wlanBssEntries[itemIndex].dot11Bssid[0],
pWlanBssList^.wlanBssEntries[itemIndex].dot11Bssid[1],
pWlanBssList^.wlanBssEntries[itemIndex].dot11Bssid[2],
pWlanBssList^.wlanBssEntries[itemIndex].dot11Bssid[3],
pWlanBssList^.wlanBssEntries[itemIndex].dot11Bssid[4],
pWlanBssList^.wlanBssEntries[itemIndex].dot11Bssid[5]]));
end;
end
else
DisplayError('Error in the WlanGetNetworkBssList() function call', lastError);
finally
if pData<>nil then
WlanFreeMemory(pData);
if pWlanBssList<>nil then
WlanFreeMemory(pWlanBssList);
end;
end;
end;
这被称为如下：
function TForm1.ScanWifi(): THandle;
const
WLAN_AVAILABLE_NETWORK_INCLUDE_ALL_ADHOC_PROFILES = $00000001;
var
hClient : THandle;
dwVersion : DWORD;
lastError : DWORD;
pInterface : Pndu_WLAN_INTERFACE_INFO_LIST;
i : Integer;
j : Integer;
pAvailableNetworkList: Pndu_WLAN_AVAILABLE_NETWORK_LIST;
interfaceGuid : TGUID;
BSSID : string;
begin
lastError:=WlanOpenHandle(NDU_WLAN_API_VERSION, nil, @dwVersion, @hClient);
if lastError<> ERROR_SUCCESS then
begin
//DisplayError('Error in the WlanOpenHandle() function call', lastError);
Result := 0;
Exit;
end;
//L(Format('Requested WLAN interface version [%d], negotiated version [%d]', [NDU_WLAN_API_VERSION, dwVersion]));
Result := hClient;
try
lastError:=WlanEnumInterfaces(hClient, nil, @pInterface);
try
if lastError<> ERROR_SUCCESS then
begin
//DisplayError('Errorin the WlanEnumInterfaces() function call', lastError);
Exit;
end;
for i := 0 to pInterface^.dwNumberOfItems - 1 do
begin
interfaceGuid:= pInterface^.InterfaceInfo[i].InterfaceGuid;
lastError:=WlanGetAvailableNetworkList(hClient,
@interfaceGuid,
WLAN_AVAILABLE_NETWORK_INCLUDE_ALL_ADHOC_PROFILES,
nil,
pAvailableNetworkList);
try
if lastError<> ERROR_SUCCESS then
begin
//DisplayError('Error WlanGetAvailableNetworkList', lastError);
Exit;
end
else
begin
for j := 0 to pAvailableNetworkList^.dwNumberOfItems - 1 do
Begin
BSSID := GetBssid(hClient,
interfaceGuid,
@pAvailableNetworkList^.Network[j].dot11Ssid,
pAvailableNetworkList^.Network[j].dot11BssType,
pAvailableNetworkList^.Network[j].bSecurityEnabled
);
//FAPList.AddOrSetValue(BSSID,J);
end;
end;
finally
if pAvailableNetworkList <> nil then
WlanFreeMemory(pAvailableNetworkList);
end;
end;
finally
if pInterface <> nil then
WlanFreeMemory(pInterface);
end;
finally
WlanCloseHandle(FhClient, nil);
end;
end;
比较两个应用程序之间的数据，唯一的区别是结果（pWlanBssList），如下所示（left=console，right=VCL）：
