BSD Sockets Interface Programmer's Guide

64 Chapter 3

Advanced Topics for Stream Sockets

Socket Options

• SO_RCVTIMEO

The following socket options toggle socket behavior. optval is an integer

containing a boolean ﬂag for the behavior (1 = on, 0 = off):

• SO_KEEPALIVE

• SO_DEBUG

• SO_DONTROUTE

• SO_USELOOPBACK

• SO_REUSEADDR

• SO_OOBINLINE

• SO_REUSEPORT

The SO_LINGER option is a combination. It sets a linger value, and also

toggles linger behavior on and off. In previous releases

SO_DONTLINGER was supported. For SO_LINGER, optval points to a

struct linger, deﬁned in /usr/include/sys/socket.h. The

structure contains an integer boolean ﬂag to toggle behavior on/off, and

an integer linger value. Refer to the getsockopt(2) man page for more

information on getsockopt.

setsockopt and its parameters are described in the following table:

Include ﬁles: #include <sys/types.h>

#include <sys/socket.h>

System call: setsockopt(s, level, optname, optval, optlen)

int s, level, optname;

char *optval;

int optlen;

Parameter

Description of

Contents

INPUT Value

s socket descriptor socket descriptor for

which options are to be set

level protocol level SOL_SOCKET