SCardConnectA function (winscard.h)

Article
02/09/2023

The SCardConnect function establishes a connection (using a specific resource manager context) between the calling application and a smart card contained by a specific reader. If no card exists in the specified reader, an error is returned.

Syntax

LONG SCardConnectA(
  [in]  SCARDCONTEXT  hContext,
  [in]  LPCSTR        szReader,
  [in]  DWORD         dwShareMode,
  [in]  DWORD         dwPreferredProtocols,
  [out] LPSCARDHANDLE phCard,
  [out] LPDWORD       pdwActiveProtocol
);

Parameters

[in] hContext

A handle that identifies the resource manager context. The resource manager context is set by a previous call to SCardEstablishContext.

[in] szReader

The name of the reader that contains the target card.

[in] dwShareMode

A flag that indicates whether other applications may form connections to the card.

Value	Meaning
SCARD_SHARE_SHARED	This application is willing to share the card with other applications.
SCARD_SHARE_EXCLUSIVE	This application is not willing to share the card with other applications.
SCARD_SHARE_DIRECT	This application is allocating the reader for its private use, and will be controlling it directly. No other applications are allowed access to it.

[in] dwPreferredProtocols

A bitmask of acceptable protocols for the connection. Possible values may be combined with the OR operation.

Value	Meaning
SCARD_PROTOCOL_T0	T=0 is an acceptable protocol.
SCARD_PROTOCOL_T1	T=1 is an acceptable protocol.
0	This parameter may be zero only if dwShareMode is set to SCARD_SHARE_DIRECT. In this case, no protocol negotiation will be performed by the drivers until an IOCTL_SMARTCARD_SET_PROTOCOL control directive is sent with SCardControl.

[out] phCard

A handle that identifies the connection to the smart card in the designated reader.

[out] pdwActiveProtocol

A flag that indicates the established active protocol.

Value	Meaning
SCARD_PROTOCOL_T0	T=0 is the active protocol.
SCARD_PROTOCOL_T1	T=1 is the active protocol.
SCARD_PROTOCOL_UNDEFINED	SCARD_SHARE_DIRECT has been specified, so that no protocol negotiation has occurred. It is possible that there is no card in the reader.

Return value

This function returns different values depending on whether it succeeds or fails.

Return code	Description
Success	SCARD_S_SUCCESS.
Failure	An error code. For more information, see Smart Card Return Values.
SCARD_E_NOT_READY	The reader was unable to connect to the card.

Remarks

The SCardConnect function is a smart card and reader access function. For more information about other access functions, see Smart Card and Reader Access Functions.

Examples

The following example creates a connection to a reader. The example assumes that hContext is a valid handle of type SCARDCONTEXT received from a previous call to SCardEstablishContext.

SCARDHANDLE     hCardHandle;
LONG            lReturn;
DWORD           dwAP;

lReturn = SCardConnect( hContext, 
                        (LPCTSTR)"Rainbow Technologies SCR3531 0",
                        SCARD_SHARE_SHARED,
                        SCARD_PROTOCOL_T0 | SCARD_PROTOCOL_T1,
                        &hCardHandle,
                        &dwAP );
if ( SCARD_S_SUCCESS != lReturn )
{
    printf("Failed SCardConnect\n");
    exit(1);  // Or other appropriate action.
}

// Use the connection.
// Display the active protocol.
switch ( dwAP )
{
    case SCARD_PROTOCOL_T0:
        printf("Active protocol T0\n"); 
        break;

    case SCARD_PROTOCOL_T1:
        printf("Active protocol T1\n"); 
        break;

    case SCARD_PROTOCOL_UNDEFINED:
    default:
        printf("Active protocol unnegotiated or unknown\n"); 
        break;
}

// Remember to disconnect (by calling SCardDisconnect).
// ...

Note

The winscard.h header defines SCardConnect as an alias that automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that is not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

Requirements

Requirement	Value
Minimum supported client	Windows XP [desktop apps only]
Minimum supported server	Windows Server 2003 [desktop apps only]
Target Platform	Windows
Header	winscard.h
Library	Winscard.lib
DLL	Winscard.dll

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