Socket Options and IOCTLs
A version of this page is also available for
4/8/2010
The socket options for Winsock 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 that can be found in the Protocol-Specific Annex.
A Windows Sockets 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 | Description | Default | Note |
|---|---|---|---|---|
SO_ACCEPTCONN |
BOOL |
Socket is listening. |
FALSE unless a WSPListen has been performed. |
|
SO_BROADCAST |
BOOL |
Socket is configured for the transmission 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. 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 typical data stream. |
FALSE |
|
SO_PROTOCOL_INFOW |
structure WSAPROTOCOL_INFOW |
Description of protocol information for the protocol that is bound to this socket. |
Protocol dependent |
Get only |
SO_RCVBUF |
int |
Buffer size for receives. |
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 |
Total per-socket buffer space reserved for sends. This is unrelated to SO_MAX_MSG _SIZE or the size of a TCP 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 |
|
Note
(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.
See Also
Concepts
Winsock Service Provider Interface (SPI)
Summary of Socket IOCTL Opcodes