WSAEnumProtocols Function (Winsock)

This topic describes the WSAEnumProtocols function, which retrieves information about available Windows Sockets protocols.

Syntax

int WSAEnumProtocols(
  LPINT                 lpiProtocols,
  LPWSAPROTOCOL_INFO    lpProtocolBuffer,
  LPDWORD               lpdwBufferLength
);

Parameters

Parameter	Description
`lpiProtocols`	A pointer to an array of integers that specifies which protocols to enumerate. Each integer should be an appropriate protocol identifier, such as `AF_INET` or `AF_UNSPEC`. If this parameter is `NULL`, WSAEnumProtocols retrieves information for all available protocols.
`lpProtocolBuffer`	A pointer to a buffer that will receive an array of `WSAPROTOCOL_INFO` structures. Each structure contains detailed information about a Windows Sockets protocol.
`lpdwBufferLength`	On input, a pointer to a `DWORD` that specifies the size, in bytes, of the buffer pointed to by `lpProtocolBuffer`. On output, if the buffer is too small, this parameter is updated with the required buffer size in bytes.

Return Value

Value	Description
On success	The number of `WSAPROTOCOL_INFO` structures returned in `lpProtocolBuffer`.
On failure	`SOCKET_ERROR` (-1). A specific error code can be retrieved by calling `WSAGetLastError`.

Remarks

The WSAEnumProtocols function is used to retrieve information about the Windows Sockets protocols installed on the system. This information includes details like the address family, socket type, protocol, and required catalog entry. This function is essential for applications that need to discover and select appropriate network protocols for their communication needs.

The WSAPROTOCOL_INFO structure provides comprehensive information about each protocol, allowing developers to make informed decisions about which protocols to use. The function can be called twice: once to determine the required buffer size and again to retrieve the actual protocol information.

Requirements

Component	Value
Minimum supported client	Windows 2000 Professional
Minimum supported server	Windows 2000 Server
Header	winsock2.h
Library	Ws2_32.lib
DLL	Ws2_32.dll