WSCEnumProtocols (Compact 2013)


This function retrieves information about available transport protocols.


int WSCEnumProtocols(
  LPINT lpiProtocols,
  LPDWORD lpdwBufferLength,
  LPINT lpErrno 


  • lpiProtocols
    [in] Null-terminated array of iProtocol values. This parameter is optional; if lpiProtocols is NULL, information on all available protocols is returned. Otherwise, information is retrieved only for those protocols listed in the array.
  • lpProtocolBuffer
    [out] Buffer that is filled with structures.
  • lpdwBufferLength
    [in, out] On input, the count of bytes in the lpProtocolBuffer buffer passed to WSCEnumProtocols. On output, the minimum buffer size that can be passed to WSCEnumProtocols to retrieve all the requested information.
  • lpErrno
    [out] Pointer to the error code.

Return Value

If no error occurs, This function returns the number of protocols to be reported on. Otherwise, a value of SOCKET_ERROR is returned and a specific error code is available in lpErrno.

Error value



One of more of the argumentsis not in a valid part of the user address space.


Indicates that one of the specified parameters was invalid.


Buffer length was too small to receive all the relevant structures and associated information. Pass in a buffer at least as large as the value returned in lpdwBufferLength.


This function is used to discover information about the collection of transport protocols installed on the local machine. This function differs from its API counterpart, WSAEnumProtocols, in that structures for all installed protocols, including layered protocols, can be obtained. (WSAEnumProtocols only returns information on base protocols and provider chains.) The lpiProtocols parameter can be used as a filter to constrain the amount of information provided. Typically, a NULL pointer is supplied so the function will return information on all available transport protocols.

A structure is provided in the buffer pointed to by lpProtocolBuffer for each requested protocol. If the supplied buffer is not large enough, as indicated by the input value of lpdwBufferLength, the value pointed to by lpdwBufferLength will be updated to indicate the required buffer size. The Windows Sockets SPI client should then obtain a large enough buffer and call this function again. The WSCEnumProtocols function cannot enumerate over multiple calls; the passed-in buffer must be large enough to hold all expected entries in order for the function to succeed. This reduces the complexity of the function and should not pose a problem because the number of protocols loaded on a machine is typically small.

The order in which the WSAPROTOCOL_INFOW structures appear in the buffer coincides with the order in which the protocol entries were registered by the service provider with the ws2.dll, or with any subsequent reordering that may have occurred through the Windows Sockets add-in supplied for establishing default transport providers.






See Also


Winsock SPI Functions