RasGetCustomAuthDataA function (ras.h)

Use the RasGetCustomAuthData function to retrieve connection-specific authentication information. This information is not specific to a particular user.


DWORD RasGetCustomAuthDataA(
  [in]      LPCSTR pszPhonebook,
  [in]      LPCSTR pszEntry,
  [out]     BYTE   *pbCustomAuthData,
  [in, out] DWORD  *pdwSizeofCustomAuthData


[in] pszPhonebook

Pointer to a null-terminated string that specifies the full path of the phone-book (PBK) file. If this parameter is NULL, the function uses the system phone book.

[in] pszEntry

Pointer to a null-terminated string that specifies an existing entry name.

[out] pbCustomAuthData

Pointer to a buffer that receives the authentication data. The caller should allocate the memory for this buffer. If the buffer is not large enough, RasGetCustomAuthData returns ERROR_BUFFER_TOO_SMALL, and the pdwSizeofEapData parameter contains the required size.

[in, out] pdwSizeofCustomAuthData

Pointer to a DWORD variable that, on input, specifies the size of the buffer pointed to by the pbCustomAuthData parameter.

If the buffer specified by the pbCustomAuthData parameter is not large enough, pdwSizeofEapData receives, on output, the required size.

Return value

If the function succeeds, the return value is ERROR_SUCCESS.

If the function fails, the return value is one of the following error codes or a value from Routing and Remote Access Error Codes or Winerror.h.

Value Meaning
The pdwSizeofCustomAuthData parameter is NULL.
The buffer pointed to by pbCustomAuthData is too small to receive the data. The pdwSizeofCustomAuthData contains the required size.

RasGetEapUserData was unable to open the specified phone-book file.


RasGetEapUserData was unable to find the specified entry in the phone book.

Use FormatMessage to retrieve the system error message that corresponds to the error code returned.



The ras.h header defines RasGetCustomAuthData as an alias which 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 not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.


Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header ras.h
Library Rasapi32.lib
DLL Rasapi32.dll

See also