bionic (3) setsockopt.3posix.gz

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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.1‐2008, <netinet_in.h>, <sys_socket.h>


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers,  Inc
       and  The  Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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 .