1.\" $NetBSD: sockopt.9,v 1.5 2008/10/28 18:42:54 wiz Exp $ 2.\" 3.\" Copyright (c) 2008 Iain Hibbert 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25.\" 26.Dd October 28, 2008 27.Dt SOCKOPT 9 28.Os 29.Sh NAME 30.Nm sockopt_init , 31.Nm sockopt_destroy , 32.Nm sockopt_get , 33.Nm sockopt_getint 34.Nm sockopt_set , 35.Nm sockopt_setint , 36.Nd socket options handling 37.Sh SYNOPSIS 38.In sys/socketvar.h 39.Ft void 40.Fn sockopt_init "struct sockopt *sopt" "int level" "int name" "size_t size" 41.Ft void 42.Fn sockopt_destroy "struct sockopt *sopt" 43.Ft int 44.Fn sockopt_get "struct sockopt *sopt" "void *value" "size_t size" 45.Ft int 46.Fn sockopt_getint "struct sockopt *sopt" "int *value" 47.Ft int 48.Fn sockopt_set "struct sockopt *sopt" "const void *value" "size_t size" 49.Ft int 50.Fn sockopt_setint "struct sockopt *sopt" "int value" 51.Sh DESCRIPTION 52The sockopt structure is used to pass a socket option and associated 53value: 54.Bd -literal -offset indent 55struct sockopt { 56 int sopt_level; /* option level */ 57 int sopt_name; /* option name */ 58 size_t sopt_size; /* data length */ 59 void * sopt_data; /* data pointer */ 60 uint8_t sopt_buf[sizeof(int)]; /* internal storage */ 61}; 62.Ed 63.Pp 64The internal storage is used for the common case of values up to integer 65size so that memory allocation is not required and sopt_data will point 66to this in that case. 67.Pp 68Note: a sockopt structure may only be used for a single level/name/size 69combination. 70If the structure is to be re-used, it must be destroyed and re-initialized 71with the new values. 72.Sh OPTIONS 73.Bl -tag -width xxxx 74.It Cd "options DIAGNOSTIC" 75Kernels compiled with the 76.Dv DIAGNOSTIC 77option will perform basic sanity checks on socket options operations. 78.El 79.Sh FUNCTIONS 80.Bl -tag -width xxxx 81.It Fn sockopt_init "sopt" "level" "name" "size" 82Initialise sockopt storage. 83If 84.Ar size 85is given, 86.Fn sockopt_init 87will arrange for sopt_data to point to a buffer of 88.Ar size 89bytes for the sockopt value. 90Where memory needs to be allocated to satisfy this, 91.Fn sockopt_init 92may sleep. 93.It Fn sockopt_destroy "sopt" 94Destroy sockopt storage, releasing any allocated memory. 95.It Fn sockopt_get "sopt" "value" "size" 96Copy out sockopt value. 97Will return 98.Er EINVAL 99if an incorrect data size is given. 100.It Fn sockopt_getint "sopt" "value" 101Common case of get sockopt integer value. 102Will return 103.Er EINVAL 104if sockopt does not contain an integer sized value. 105.It Fn sockopt_set "sopt" "value" "size" 106Copy in sockopt value. 107The sockopt structure must contain a data field of 108.Ar size 109bytes or be previously unset, in which case a data buffer may be 110allocated using 111.Xr kmem_alloc 9 112with the 113.Dv KM_NOSLEEP 114flag which may cause 115.Fn sockopt_set 116to return 117.Er ENOMEM . 118.Pp 119Note: If you need to use 120.Fn sockopt_set 121in a context where memory allocation may be required and you do not wish to 122contemplate failure, the sockopt structure can be initialised in a more suitable 123context using 124.Fn sockopt_init 125which will not fail. 126.It Fn sockopt_setint "sopt" "value" 127Common case of set sockopt integer value. 128The sockpt structure must contain an int sized data field or be previously 129unset, in which case the data pointer will be set to the internal storage. 130.El 131.Sh CODE REFERENCES 132This section describes places within the 133.Nx 134source tree where code implementing socket options can be found. 135All pathnames are relative to 136.Pa /usr/src . 137.Pp 138The function prototypes and sockopt structure are defined in the 139.Pa sys/sys/socketvar.h 140header file, and the socket options implementation is in 141.Pa sys/kern/uipc_socket.c . 142.Sh SEE ALSO 143.Xr errno 2 , 144.Xr kmem_alloc 9 145.Sh HISTORY 146The socket options KPI was inspired by a similar KPI in 147.Fx 148and 149first appeared in 150.Nx 5.0 . 151