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NF:winsock2.ioctlsocket

ioctlsocket function (winsock2.h)

The ioctlsocket function (winsock2.h) controls the I/O mode of a socket and can be used on any socket in any state.

_win32_ioctlsocket_2

ioctlsocket

ioctlsocket function [Winsock]

winsock.ioctlsocket_2

winsock/ioctlsocket

winsock\ioctlsocket_2.htm

WinSock

048fcb8d-acd3-4917-a997-dd133db399f8

08/03/2022

_win32_ioctlsocket_2, ioctlsocket, ioctlsocket function [Winsock], winsock.ioctlsocket_2, winsock/ioctlsocket

winsock2.h

Winsock2.h

Windows

Windows 8.1, Windows Vista [desktop apps \| UWP apps]

Windows Server 2003 [desktop apps \| UWP apps]

Ws2_32.lib

Ws2_32.dll

Windows

19H1

ioctlsocket

winsock2/ioctlsocket

c++

APIRef

kbSyntax

DllExport

Ws2_32.dll

ioctlsocket

ioctlsocket function

-description

The ioctlsocket function controls the I/O mode of a socket.

-parameters

-param s [in]

A descriptor identifying a socket.

-param cmd [in]

A command to perform on the socket s.

-param argp [in, out]

A pointer to a parameter for cmd.

-returns

Upon successful completion, the ioctlsocket returns zero. Otherwise, a value of SOCKET_ERROR is returned, and a specific error code can be retrieved by calling WSAGetLastError.

Error code	Meaning
WSANOTINITIALISED	A successful WSAStartup call must occur before using this function.
WSAENETDOWN	The network subsystem has failed.
WSAEINPROGRESS	A blocking Windows Sockets 1.1 call is in progress, or the service provider is still processing a callback function.
WSAENOTSOCK	The descriptor s is not a socket.
WSAEFAULT	The argp parameter is not a valid part of the user address space.

-remarks

The ioctlsocket function can be used on any socket in any state. It is used to set or retrieve some operating parameters associated with the socket, independent of the protocol and communications subsystem. Here are the supported commands to use in the cmd parameter and their semantics:

The WSAIoctl function is used to set or retrieve operating parameters associated with the socket, the transport protocol, or the communications subsystem.

The WSAIoctl function is more powerful than the ioctlsocket function and supports a large number of possible values for the operating parameters to set or retrieve.

Example Code

The following example demonstrates the use of the ioctlsocket function.

#include <winsock2.h>
#include <stdio.h>

#pragma comment(lib, "Ws2_32.lib")

void main()
{
//-------------------------
// Initialize Winsock
WSADATA wsaData;
int iResult;
u_long iMode = 0;

iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
if (iResult != NO_ERROR)
  printf("Error at WSAStartup()\n");

//-------------------------
// Create a SOCKET object.
SOCKET m_socket;
m_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (m_socket == INVALID_SOCKET) {
  printf("Error at socket(): %ld\n", WSAGetLastError());
  WSACleanup();
  return;
}

//-------------------------
// Set the socket I/O mode: In this case FIONBIO
// enables or disables the blocking mode for the 
// socket based on the numerical value of iMode.
// If iMode = 0, blocking is enabled; 
// If iMode != 0, non-blocking mode is enabled.

iResult = ioctlsocket(m_socket, FIONBIO, &iMode);
if (iResult != NO_ERROR)
  printf("ioctlsocket failed with error: %ld\n", iResult);
  

}

Compatibility

This ioctlsocket function performs only a subset of functions on a socket when compared to the ioctl function found in Berkeley sockets. The ioctlsocket function has no command parameter equivalent to the FIOASYNC of ioctl, and SIOCATMARK is the only socket-level command that is supported by ioctlsocket.