1.\" $NetBSD: sockopt.9,v 1.7 2009/09/04 11:34:38 plunky 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 September 4, 2009 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 53.Ft sockopt 54structure is used to pass a socket option and associated value: 55.Bd -literal -offset indent 56struct sockopt { 57 int sopt_level; /* option level */ 58 int sopt_name; /* option name */ 59 size_t sopt_size; /* data length */ 60 void * sopt_data; /* data pointer */ 61 uint8_t sopt_buf[sizeof(int)]; /* internal storage */ 62}; 63.Ed 64.Pp 65The internal storage is used for the common case of values up to integer 66size so that memory allocation is not required and sopt_data will point 67to this in that case. 68.Pp 69Rather than provide accessor functions, the 70.Ft sockopt 71structure is public and the contents are expected to be internally 72consistent, but the normal practice would be to use the appropriate methods 73for storage and retrieval of values where a known datatype is expected, 74as the size will be verified. 75.Pp 76Note: a sockopt structure may only be used for a single level/name/size 77combination. 78If the structure is to be re-used, it must be destroyed and re-initialized 79with the new values. 80.Sh OPTIONS 81.Bl -tag -width xxxx 82.It Cd "options DIAGNOSTIC" 83Kernels compiled with the 84.Dv DIAGNOSTIC 85option will perform basic sanity checks on socket options operations. 86.El 87.Sh FUNCTIONS 88.Bl -tag -width xxxx 89.It Fn sockopt_init "sopt" "level" "name" "size" 90Initialise sockopt storage. 91If 92.Ar size 93is given, 94.Fn sockopt_init 95will arrange for sopt_data to point to a buffer of 96.Ar size 97bytes for the sockopt value. 98Where memory needs to be allocated to satisfy this, 99.Fn sockopt_init 100may sleep. 101.It Fn sockopt_destroy "sopt" 102Destroy sockopt storage, releasing any allocated memory. 103.It Fn sockopt_get "sopt" "value" "size" 104Copy out sockopt value. 105Will return 106.Er EINVAL 107if an incorrect data size is given. 108.It Fn sockopt_getint "sopt" "value" 109Common case of get sockopt integer value. 110Will return 111.Er EINVAL 112if sockopt does not contain an integer sized value. 113.It Fn sockopt_set "sopt" "value" "size" 114Copy in sockopt value. 115The sockopt structure must contain a data field of 116.Ar size 117bytes or be previously unset, in which case a data buffer may be 118allocated using 119.Xr kmem_alloc 9 120with the 121.Dv KM_NOSLEEP 122flag which may cause 123.Fn sockopt_set 124to return 125.Er ENOMEM . 126.Pp 127Note: If you need to use 128.Fn sockopt_set 129in a context where memory allocation may be required and you do not wish to 130contemplate failure, the sockopt structure can be initialised in a more suitable 131context using 132.Fn sockopt_init 133which will not fail. 134.It Fn sockopt_setint "sopt" "value" 135Common case of set sockopt integer value. 136The sockpt structure must contain an int sized data field or be previously 137unset, in which case the data pointer will be set to the internal storage. 138.El 139.Sh CODE REFERENCES 140This section describes places within the 141.Nx 142source tree where code implementing socket options can be found. 143All pathnames are relative to 144.Pa /usr/src . 145.Pp 146The function prototypes and sockopt structure are defined in the 147.Pa sys/sys/socketvar.h 148header file, and the socket options implementation is in 149.Pa sys/kern/uipc_socket.c . 150.Sh SEE ALSO 151.Xr errno 2 , 152.Xr kmem 9 153.Sh HISTORY 154The socket options KPI was inspired by a similar KPI in 155.Fx 156and 157first appeared in 158.Nx 5.0 . 159