Home | History | Annotate | Line # | Download | only in man9
sockopt.9 revision 1.1.2.2 
 $NetBSD: sockopt.9,v 1.1.2.2 2008/09/18 04:38:09 wrstuden Exp $

 Copyright (c) 2008 Iain Hibbert
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:
 1. Redistributions of source code must retain the above copyright
 notice, this list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright
 notice, this list of conditions and the following disclaimer in the
 documentation and/or other materials provided with the distribution.

 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

.Dd August 6, 2008
.Dt SOCKOPT 9
.Os
.Sh NAME
.Nm sockopt_init ,
.Nm sockopt_destroy ,
.Nm sockopt_get ,
.Nm sockopt_getint
.Nm sockopt_set ,
.Nm sockopt_setint ,
.Nd socket options handling
.Sh SYNOPSIS
n sys/socketvar.h .Ft void
.Fn sockopt_init "struct sockopt *sopt" "int level" "int name" "size_t size"
.Ft void
.Fn sockopt_destroy "struct sockopt *sopt"
.Ft int
.Fn sockopt_get "struct sockopt *sopt" "void *value" "size_t size"
.Ft int
.Fn sockopt_getint "struct sockopt *sopt" "int *value"
.Ft int
.Fn sockopt_set "struct sockopt *sopt" "const void *value" "size_t size"
.Ft int
.Fn sockopt_setint "struct sockopt *sopt" "int value"
.Sh DESCRIPTION
The sockopt structure is used to pass a socket option and associated
value:
d -literal -offset indent struct sockopt {
 int sopt_level; /* option level */
 int sopt_name; /* option name */
 size_t sopt_size; /* data length */
 void * sopt_data; /* data pointer */
 uint8_t sopt_buf[sizeof(int)]; /* internal storage */
};
.Ed

p
The internal storage is used for the common case of values up to integer
size so that memory allocation is not required and sopt_data will point
to this in that case.

p
Note: a sockopt structure may only be used for a single level/name/size
combination.
If the structure is to be re-used, it must be destroyed and re-initialized
with the new values.
.Sh OPTIONS
l -tag -width xxxx t Cd "options DIAGNOSTIC" Kernels compiled with the
.Dv DIAGNOSTIC
option will perform basic sanity checks on socket options operations.
.El
.Sh FUNCTIONS
l -tag -width xxxx t Fn sockopt_init "sopt" "level" "name" "size" Initialise sockopt storage.
If
.Ar size
is given,
.Fn sockopt_init
will arrange for sopt_data to point to a buffer of
.Ar size
bytes for the sockopt value.
t Fn sockopt_destroy "sopt" Destroy sockopt storage, releasing any allocated memory.
t Fn sockopt_get "sopt" "value" "size" Copy out sockopt value.
Will return
.Dv EINVAL 
if an incorrect data size is given.
t Fn sockopt_getint "sopt" "value" Common case of get sockopt integer value.
Will return
.Dv EINVAL 
if sockopt does not contain an integer sized value.
t Fn sockopt_set "sopt" "value" "size" Copy in sockopt value.
The sockopt structure must contain a data field of
.Ar size
bytes or be previously unset, in which case a data buffer may be
allocated using
.Dv M_WAITOK .
t Fn sockopt_setint "sopt" "value" Common case of set sockopt integer value.
The sockpt structure must contain an int sized data field or be previously
unset, in which case the data pointer will be set to the internal storage.
.El
.Sh CODE REFERENCES
This section describes places within the
.Nx
source tree where code implementing socket options can be found.
All pathnames are relative to

a /usr/src .

p
The function prototypes and sockopt structure are defined in the

a sys/sys/socketvar.h
header file, and the socket options implementation is in

a sys/kern/uipc_socket.c .
.Sh SEE ALSO
.Xr errno 2 ,
.Xr malloc 9
.Sh HISTORY
The socket options KPI was inspired by a similar KPI in FreeBSD and
first appeared in
.Nx 5.0 .