Internet - saber se esta conectada

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///////////////////////////////// EXEMPLO 1/3

function FuncAvail(VLibraryname, VFunctionname: string; var VPointer: pointer): boolean;

// this function check if VFunctionname exists in VLibraryname

var

Vlib: tHandle;

begin

Result := false;

if LoadLibrary(PChar(VLibraryname)) = 0 then

exit;

Vlib := GetModuleHandle(PChar(VLibraryname));

if Vlib <> 0 then

begin

VPointer := GetProcAddress(Vlib, PChar(VFunctionname));

if VPointer <> NIL then

Result := true;

end;

Code Button1 on a Form1:

procedure TForm1.Button1Click(Sender: TObject);

// Call shell32.dll for highter Win98

// else call url.dll

var

InetIsOffline : function(dwFlags: DWORD):BOOL; stdcall;

begin

if FuncAvail('url.dll', 'InetIsOffline', @InetIsOffline) then

if InetIsOffLine(0) then

ShowMessage('Not connected')

else

ShowMessage('Connected!');

end;

/////////////////////////////////////// EXEMPLO 2/3

...check if I am connected to the internet ?

interface

uses

Windows, SysUtils, Registry, WinSock, WinInet;

type

TConnectionType = (ctNone, ctProxy, ctDialup);

function ConnectedToInternet : TConnectionType;

function RasConnectionCount : Integer;

implementation

//For RasConnectionCount =======================

const

cERROR_BUFFER_TOO_SMALL = 603;

cRAS_MaxEntryName = 256;

cRAS_MaxDeviceName = 128;

cRAS_MaxDeviceType = 16;

type

ERasError = class(Exception);

HRASConn = DWord;

PRASConn = ^TRASConn;

TRASConn = record

dwSize: DWORD;

rasConn: HRASConn;

szEntryName: Array[0..cRAS_MaxEntryName] Of Char;

szDeviceType : Array[0..cRAS_MaxDeviceType] Of Char;

szDeviceName : Array [0..cRAS_MaxDeviceName] of char;

end;

TRasEnumConnections =

function (RASConn: PrasConn; { buffer to receive Connections data }

var BufSize: DWord; { size in bytes of buffer }

var Connections: DWord { number of Connections written to buffer }

): LongInt; stdcall;

//End RasConnectionCount =======================

function ConnectedToInternet: TConnectionType;

var

Reg : TRegistry;

bUseProxy : Boolean;

UseProxy : LongWord;

begin

Result := ctNone;

Reg := TRegistry.Create;

with REG do

try

RootKey := HKEY_CURRENT_USER;

if OpenKey('\Software\Microsoft\Windows\CurrentVersion\Internet settings',False) then begin

//I just try to read it, and trap an exception

if GetDataType('ProxyEnable') = rdBinary then

ReadBinaryData('ProxyEnable', UseProxy, SizeOf(LongWord) )

else begin

bUseProxy := ReadBool('ProxyEnable');

if bUseProxy then

UseProxy := 1

else

UseProxy := 0;

end;

if (UseProxy <> 0) and ( ReadString('ProxyServer') <> '' ) then Result := ctProxy;

end;

except

//Obviously not connected through a proxy

end;

finally

Free;

end;

//We can check RasConnectionCount even if dialup networking is not installed

//simply because it will return 0 if the DLL is not found.

if Result = ctNone then begin

if RasConnectionCount > 0 then Result := ctDialup;

end;

function RasConnectionCount : Integer;

var

RasDLL : HInst;

Conns : Array[1..4] of TRasConn;

RasEnums : TRasEnumConnections;

BufSize : DWord;

NumConns : DWord;

RasResult : Longint;

begin

Result := 0;

//Load the RAS DLL

RasDLL := LoadLibrary('rasapi32.dll');

if RasDLL = 0 then exit;

try

RasEnums := GetProcAddress(RasDLL,'RasEnumConnectionsA');

if @RasEnums = nil then

raise ERasError.Create('RasEnumConnectionsA not found in rasapi32.dll');

Conns[1].dwSize := Sizeof (Conns[1]);

BufSize := SizeOf(Conns);

RasResult := RasEnums(@Conns, BufSize, NumConns);

If (RasResult = 0) or (Result = cERROR_BUFFER_TOO_SMALL) then Result := NumConns;

finally

FreeLibrary(RasDLL);

end;

/////////////////////////////////////////// EXEMPLO 3/3

// Detalhe, este não roda em WindowsNT.

uses WinInet;

function NETConectada: Boolean;

const INTERNET_CONNECTION_MODEM=1; // Conectado via modem

INTERNET_CONNECTION_LAN=2; // Conectado via rede

INTERNET_CONNECTION_PROXY=4; // Conectado via proxie

INTERNET_CONNECTION_MODEM_BUSY=8; // Modem ocupado com um trabalho não

internet

var dwConnectionTypes : DWORD;

begin

dwConnectionTypes:=INTERNET_CONNECTION_MODEM+

INTERNET_CONNECTION_LAN+

INTERNET_CONNECTION_PROXY;

Result:=InternetGetConnectedState(@dwConnectionTypes,0);

end;

///////////////////////////////////////// EXEMPLO 4/4

interface

uses

Windows, SysUtils, Registry, WinSock, WinInet;

type

TConnectionType = (ctNone, ctProxy, ctDialup);

function ConnectedToInternet: TConnectionType;

function RasConnectionCount: Integer;

implementation

//For RasConnectionCount =======================

const

cERROR_BUFFER_TOO_SMALL = 603;

cRAS_MaxEntryName = 256;

cRAS_MaxDeviceName = 128;

cRAS_MaxDeviceType = 16;

type

ERasError = class(Exception);

HRASConn = DWORD;

PRASConn = ^TRASConn;

TRASConn = record

dwSize: DWORD;

rasConn: HRASConn;

szEntryName: array[0..cRAS_MaxEntryName] of Char;

szDeviceType: array[0..cRAS_MaxDeviceType] of Char;

szDeviceName: array [0..cRAS_MaxDeviceName] of Char;

end;

TRasEnumConnections =

function(RASConn: PrasConn; { buffer to receive Connections data }

var BufSize: DWORD; { size in bytes of buffer }

var Connections: DWORD { number of Connections written to buffer }

): Longint;

stdcall;

//End RasConnectionCount =======================

function ConnectedToInternet: TConnectionType;

var

Reg: TRegistry;

bUseProxy: Boolean;

UseProxy: LongWord;

begin

Result := ctNone;

Reg := TRegistry.Create;

with REG do

try

RootKey := HKEY_CURRENT_USER;

if OpenKey('\Software\Microsoft\Windows\CurrentVersion\Internet settings', False) then

begin

//I just try to read it, and trap an exception

if GetDataType('ProxyEnable') = rdBinary then

ReadBinaryData('ProxyEnable', UseProxy, SizeOf(Longword))

else

begin

bUseProxy := ReadBool('ProxyEnable');

if bUseProxy then

UseProxy := 1

else

UseProxy := 0;

end;

if (UseProxy <> 0) and (ReadString('ProxyServer') <> '') then

Result := ctProxy;

end;

except

//Obviously not connected through a proxy

end;

finally

Free;

end;

//We can check RasConnectionCount even if dialup networking is not installed

//simply because it will return 0 if the DLL is not found.

if Result = ctNone then

begin

if RasConnectionCount > 0 then Result := ctDialup;

end;

function RasConnectionCount: Integer;

var

RasDLL: HInst;

Conns: array[1..4] of TRasConn;

RasEnums: TRasEnumConnections;

BufSize: DWORD;

NumConns: DWORD;

RasResult: Longint;

begin

Result := 0;

//Load the RAS DLL

RasDLL := LoadLibrary('rasapi32.dll');

if RasDLL = 0 then Exit;

try

RasEnums := GetProcAddress(RasDLL, 'RasEnumConnectionsA');

if @RasEnums = nil then

raise ERasError.Create('RasEnumConnectionsA not found in rasapi32.dll');

Conns[1].dwSize := SizeOf(Conns[1]);

BufSize := SizeOf(Conns);

RasResult := RasEnums(@Conns, BufSize, NumConns);

if (RasResult = 0) or (Result = cERROR_BUFFER_TOO_SMALL) then Result := NumConns;

finally

FreeLibrary(RasDLL);

end;