setsockopt

SETSOCKOPT(3P)              POSIX Programmer's Manual             SETSOCKOPT(3P)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the corresponding
       Linux manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.

NAME
       setsockopt — set the socket options

SYNOPSIS
       #include <sys/socket.h>

       int setsockopt(int socket, int level, int option_name,
           const void *option_value, socklen_t option_len);

DESCRIPTION
       The setsockopt() function shall set the option specified by the
       option_name argument, at the protocol level specified by the level
       argument, to the value pointed to by the option_value argument for the
       socket associated with the file descriptor specified by the socket
       argument.

       The level argument specifies the protocol level at which the option
       resides. To set options at the socket level, specify the level argument
       as SOL_SOCKET. To set options at other levels, supply the appropriate
       level identifier for the protocol controlling the option. For example, to
       indicate that an option is interpreted by the TCP (Transport Control
       Protocol), set level to IPPROTO_TCP as defined in the <netinet/in.h>
       header.

       The option_name argument specifies a single option to set. It can be one
       of the socket-level options defined in <sys_socket.h> and described in
       Section 2.10.16, Use of Options.  If option_name is equal to SO_RCVTIMEO
       or SO_SNDTIMEO and the implementation supports setting the option, it is
       unspecified whether the struct timeval pointed to by option_value is
       stored as provided by this function or is rounded up to align with the
       resolution of the clock being used. If setsockopt() is called with
       option_name equal to SO_ACCEPTCONN, SO_ERROR, or SO_TYPE, the behavior is
       unspecified.

RETURN VALUE
       Upon successful completion, setsockopt() shall return 0. Otherwise, -1
       shall be returned and errno set to indicate the error.

ERRORS
       The setsockopt() function shall fail if:

       EBADF  The socket argument is not a valid file descriptor.

       EDOM   The send and receive timeout values are too big to fit into the
              timeout fields in the socket structure.

       EINVAL The specified option is invalid at the specified socket level or
              the socket has been shut down.

       EISCONN
              The socket is already connected, and a specified option cannot be
              set while the socket is connected.

       ENOPROTOOPT
              The option is not supported by the protocol.

       ENOTSOCK
              The socket argument does not refer to a socket.

       The setsockopt() function may fail if:

       ENOMEM There was insufficient memory available for the operation to
              complete.

       ENOBUFS
              Insufficient resources are available in the system to complete the
              call.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       The setsockopt() function provides an application program with the means
       to control socket behavior. An application program can use setsockopt()
       to allocate buffer space, control timeouts, or permit socket data
       broadcasts. The <sys/socket.h> header defines the socket-level options
       available to setsockopt().

       Options may exist at multiple protocol levels. The SO_ options are always
       present at the uppermost socket level.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       Section 2.10, Sockets, bind(), endprotoent(), getsockopt(), socket()

       The Base Definitions volume of POSIX.1‐2017, <netinet_in.h>,
       <sys_socket.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute
       of Electrical and Electronics Engineers, Inc and The Open Group.  In the
       event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group Standard is
       the referee document. The original Standard can be obtained online at
       http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are most
       likely to have been introduced during the conversion of the source files
       to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                   2017                        SETSOCKOPT(3P)