Socket Options and IOCTLs

Some of the socket options for Windows Sockets 2 are summarized in the following table. More detailed information is provided in section 4 under WSPGetSockOpt and/or WSPSetSockOpt. There are other new protocol-specific socket options which can be found in the Protocol-Specific Annex. A complete list of Socket Options for Windows Sockets are available in the Winsock reference.

For a summary of some of the Winsock Ioctls, see Summary of Socket Ioctl Opcodes. A complete list of Winsock IOCTLs are available in the Winsock reference.

Summary of Common Socket Options

A Winsock service provider must recognize all of these options, and (for WSPGetSockOpt) return plausible values for each. The default value for each option is shown in the following table.

Value

Type

Meaning

Default

Note

SO_ACCEPTCONN

BOOL

Socket is listening.

FALSE unless a WSPListen has been performed.

SO_BROADCAST

BOOL

Socket is configured for the transmission and receipt of broadcast messages.

FALSE

SO_DEBUG

BOOL

Debugging is enabled.

FALSE

(i)

SO_DONTLINGER

BOOL

If true, the SO_LINGER option is disabled.

TRUE

SO_DONTROUTE

BOOL

Routing is disabled. Succeeds but is ignored on AF_INET sockets; fails on AF_INET6 sockets with WSAENOPROTOOPT. Not supported on ATM sockets (results in an error).

FALSE

(i)

SO_ERROR

int

Retrieves error status and clear.

0

SO_GROUP_ID

GROUP

Reserved.

NULL

Get only

SO_GROUP_PRIORITY

int

Reserved.

0

SO_KEEPALIVE

BOOL

Keepalives are being sent. Not supported on ATM sockets (results in an error).

FALSE

(i)

SO_LINGER

Structure linger

Returns the current linger options.

l_onoff is 0

SO_MAX_MSG_SIZE

int

Maximum outbound size of a message for message socket types. There is no provision to determine the maximum inbound message size. Has no meaning for stream-oriented sockets.

Implementation dependent

Get only

SO_OOBINLINE

BOOL

OOB data is being received in the normal data stream.

FALSE

SO_PROTOCOL_INFOW

structure WSAPROTOCOL_INFO

Description of protocol information for the protocol that is bound to this socket.

Protocol dependent

Get only

SO_RCVBUF

int

The total per-socket buffer space reserved for receives. This is unrelated to SO_MAX_MSG_SIZE and does not necessarily correspond to the size of the TCP receive window.

Implementation dependent

(i)

SO_REUSEADDR

BOOL

The address to which this socket is bound can be used by others. Not applicable on ATM sockets.

FALSE

SO_SNDBUF

int

The total per-socket buffer space reserved for sends. This is unrelated to SO_MAX_MSG_SIZE and does not necessarily correspond to the size of a TCP send window.

Implementation dependent

(i)

SO_TYPE

int

The type of the socket (for example, SOCK_STREAM).

As created through socket.

PVD_CONFIG

char FAR *

An opaque data structure object containing configuration information of the service provider.

Implementation dependent

TCP_NODELAY

BOOL

Disables the Nagle algorithm for send coalescing.

Implementation dependent

(i) A service provider may silently ignore this option on WSPSetSockOpt and return a constant value for WSPGetSockOpt, or it may accept a value for WSPSetSockOpt and return the corresponding value in WSPGetSockOpt without using the value in any way.

 

Related topics

Socket Options

SOL_SOCKET Socket Options

IPPROTO_TCP Socket Options

IPPROTO_UDP Socket Options

Winsock IOCTLs