1.\" Copyright (c) 1996-1999 Whistle Communications, Inc. 2.\" All rights reserved. 3.\" 4.\" Subject to the following obligations and disclaimer of warranty, use and 5.\" redistribution of this software, in source or object code forms, with or 6.\" without modifications are expressly permitted by Whistle Communications; 7.\" provided, however, that: 8.\" 1. Any and all reproductions of the source or object code must include the 9.\" copyright notice above and the following disclaimer of warranties; and 10.\" 2. No rights are granted, in any manner or form, to use Whistle 11.\" Communications, Inc. trademarks, including the mark "WHISTLE 12.\" COMMUNICATIONS" on advertising, endorsements, or otherwise except as 13.\" such appears in the above copyright notice or in the software. 14.\" 15.\" THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND 16.\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO 17.\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, 18.\" INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF 19.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. 20.\" WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY 21.\" REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS 22.\" SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. 23.\" IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES 24.\" RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING 25.\" WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 26.\" PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR 27.\" SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY 28.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30.\" THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY 31.\" OF SUCH DAMAGE. 32.\" 33.\" Author: Archie Cobbs <archie@FreeBSD.org> 34.\" 35.\" $FreeBSD: src/share/man/man4/ng_socket.4,v 1.14.2.1 2001/12/21 09:00:51 ru Exp $ 36.\" $Whistle: ng_socket.8,v 1.5 1999/01/25 23:46:27 archie Exp $ 37.\" 38.Dd January 19, 1999 39.Dt NG_SOCKET 4 40.Os 41.Sh NAME 42.Nm ng_socket 43.Nd netgraph socket node type 44.Sh SYNOPSIS 45.In netgraph/ng_message.h 46.In netgraph/socket/ng_socket.h 47.Sh DESCRIPTION 48A 49.Nm socket 50node is both a 51.Bx 52socket and a netgraph node. The 53.Nm 54node type allows user-mode processes to participate in the kernel 55.Xr netgraph 4 56networking subsystem using the 57.Bx 58socket interface. The process must have 59root privileges to be able to create netgraph sockets however once created, 60any process that has one may use it. 61.Pp 62A new 63.Nm 64node is created by creating a new socket of type 65.Dv NG_CONTROL 66in the protocol family 67.Dv PF_NETGRAPH , 68using the 69.Xr socket 2 70system call. 71Any control messages received by the node 72and not having a cookie value of 73.Dv NGM_SOCKET_COOKIE 74are received by the process, using 75.Xr recvfrom 2 ; 76the socket address argument is a 77.Dv "struct sockaddr_ng" 78containing the sender's netgraph address. Conversely, control messages 79can be sent to any node by calling 80.Xr sendto 2 , 81supplying the recipient's address in a 82.Dv "struct sockaddr_ng" . 83The 84.Xr bind 2 85system call may be used to assign a global netgraph name to the node. 86.Pp 87To transmit and receive netgraph data packets, a 88.Dv NG_DATA 89socket must also be created using 90.Xr socket 2 91and associated with a 92.Nm 93node. 94.Dv NG_DATA sockets do not automatically 95have nodes associated with them; they are bound to a specific node via the 96.Xr connect 2 97system call. The address argument is the netgraph address of the 98.Nm 99node already created. Once a data socket is associated with a node, 100any data packets received by the node are read using 101.Xr recvfrom 2 102and any packets to be sent out from the node are written using 103.Xr sendto 2 . 104In the case of data sockets, the 105.Dv "struct sockaddr_ng" 106contains the name of the 107.Em hook 108on which the data was received or should be sent. 109.Pp 110As a special case, to allow netgraph data sockets to be used as stdin or stdout 111on naive programs, a 112.Xr sendto 2 113with a NULL sockaddr pointer, a 114.Xr send 2 115or a 116.Xr write 2 117will succeed in the case where there is exactly ONE hook attached to 118the socket node, (and thus the path is unambiguous). 119.Pp 120There is a user library that simplifies using netgraph sockets; see 121.Xr netgraph 3 . 122.Sh HOOKS 123This node type supports hooks with arbitrary names (as long as 124they are unique) and always accepts hook connection requests. 125.Sh CONTROL MESSAGES 126This node type supports the generic control messages, plus the following: 127.Bl -tag -width foo 128.It Dv NGM_SOCK_CMD_NOLINGER 129When the last hook is removed from this node, it will shut down as 130if it had received a 131.Dv NGM_SHUTDOWN 132message. Attempts to access the sockets associated will return 133.Er ENOTCONN . 134.It Dv NGM_SOCK_CMD_LINGER 135This is the default mode. When the last hook is removed, the node will 136continue to exist, ready to accept new hooks until it 137is explicitly shut down. 138.El 139.Pp 140All other messages 141with neither the 142.Dv NGM_SOCKET_COOKIE 143or 144.Dv NGM_GENERIC_COOKIE 145will be passed unaltered up the 146.Dv NG_CONTROL 147socket. 148.Sh SHUTDOWN 149This node type shuts down and disappears when both the associated 150.Dv NG_CONTROL 151and 152.Dv NG_DATA 153sockets have been closed, or a 154.Dv NGM_SHUTDOWN 155control message is received. In the latter case, attempts to write 156to the still-open sockets will return 157.Er ENOTCONN . 158If the 159.Dv NGM_SOCK_CMD_NOLINGER 160message has been received, closure of the last hook will also initiate 161a shutdown of the node. 162.Sh SEE ALSO 163.Xr socket 2 , 164.Xr netgraph 3 , 165.Xr netgraph 4 , 166.Xr ng_ksocket 4 , 167.Xr ngctl 8 168.Sh HISTORY 169The 170.Nm 171node type was implemented in 172.Fx 4.0 . 173.Sh AUTHORS 174.An Julian Elischer Aq Mt julian@FreeBSD.org 175.Sh BUGS 176It is not possible to reject the connection of a hook, though any 177data received on that hook can certainly be ignored. 178.Pp 179The controlling process is not notified of all events that an in-kernel node 180would be notified of, e.g. a new hook, or hook removal. We should define 181some node-initiated messages for this purpose (to be sent up the control 182socket). 183