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.\" $FreeBSD$ 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 sys/types.h 46.In netgraph/ng_socket.h 47.Sh DESCRIPTION 48A 49.Nm socket 50node is both a 51.Bx 52socket and a netgraph node. 53The 54.Nm 55node type allows user-mode processes to participate in the kernel 56.Xr netgraph 4 57networking subsystem using the 58.Bx 59socket interface. 60The process must have 61root privileges to be able to create netgraph sockets however once created, 62any process that has one may use it. 63.Pp 64A new 65.Nm 66node is created by creating a new socket of type 67.Dv NG_CONTROL 68in the protocol family 69.Dv PF_NETGRAPH , 70using the 71.Xr socket 2 72system call. 73Any control messages received by the node 74and not having a cookie value of 75.Dv NGM_SOCKET_COOKIE 76are received by the process, using 77.Xr recvfrom 2 ; 78the socket address argument is a 79.Dv "struct sockaddr_ng" 80containing the sender's netgraph address. 81Conversely, control messages can be sent to any node by calling 82.Xr sendto 2 , 83supplying the recipient's address in a 84.Dv "struct sockaddr_ng" . 85The 86.Xr bind 2 87system call may be used to assign a global netgraph name to the node. 88.Pp 89To transmit and receive netgraph data packets, a 90.Dv NG_DATA 91socket must also be created using 92.Xr socket 2 93and associated with a 94.Nm 95node. 96.Dv NG_DATA sockets do not automatically 97have nodes associated with them; they are bound to a specific node via the 98.Xr connect 2 99system call. 100The address argument is the netgraph address of the 101.Nm 102node already created. 103Once a data socket is associated with a node, 104any data packets received by the node are read using 105.Xr recvfrom 2 106and any packets to be sent out from the node are written using 107.Xr sendto 2 . 108In the case of data sockets, the 109.Dv "struct sockaddr_ng" 110contains the name of the 111.Em hook 112on which the data was received or should be sent. 113.Pp 114As a special case, to allow netgraph data sockets to be used as stdin or stdout 115on naive programs, a 116.Xr sendto 2 117with a NULL sockaddr pointer, a 118.Xr send 2 119or a 120.Xr write 2 121will succeed in the case where there is exactly ONE hook attached to 122the socket node, (and thus the path is unambiguous). 123.Pp 124There is a user library that simplifies using netgraph sockets; see 125.Xr netgraph 3 . 126.Sh HOOKS 127This node type supports hooks with arbitrary names (as long as 128they are unique) and always accepts hook connection requests. 129.Sh CONTROL MESSAGES 130This node type supports the generic control messages, plus the following: 131.Bl -tag -width foo 132.It Dv NGM_SOCK_CMD_NOLINGER 133When the last hook is removed from this node, it will shut down as 134if it had received a 135.Dv NGM_SHUTDOWN 136message. 137Attempts to access the sockets associated will return 138.Er ENOTCONN . 139.It Dv NGM_SOCK_CMD_LINGER 140This is the default mode. 141When the last hook is removed, the node will 142continue to exist, ready to accept new hooks until it 143is explicitly shut down. 144.El 145.Pp 146All other messages 147with neither the 148.Dv NGM_SOCKET_COOKIE 149or 150.Dv NGM_GENERIC_COOKIE 151will be passed unaltered up the 152.Dv NG_CONTROL 153socket. 154.Sh SHUTDOWN 155This node type shuts down and disappears when both the associated 156.Dv NG_CONTROL 157and 158.Dv NG_DATA 159sockets have been closed, or a 160.Dv NGM_SHUTDOWN 161control message is received. 162In the latter case, attempts to write 163to the still-open sockets will return 164.Er ENOTCONN . 165If the 166.Dv NGM_SOCK_CMD_NOLINGER 167message has been received, closure of the last hook will also initiate 168a shutdown of the node. 169.Sh SEE ALSO 170.Xr socket 2 , 171.Xr netgraph 3 , 172.Xr netgraph 4 , 173.Xr ng_ksocket 4 , 174.Xr ngctl 8 175.Sh HISTORY 176The 177.Nm 178node type was implemented in 179.Fx 4.0 . 180.Sh AUTHORS 181.An Julian Elischer Aq julian@FreeBSD.org 182.Sh BUGS 183It is not possible to reject the connection of a hook, though any 184data received on that hook can certainly be ignored. 185.Pp 186The controlling process is not notified of all events that an in-kernel node 187would be notified of, e.g.\& a new hook, or hook removal. 188Some node-initiated messages should be defined for this purpose (to be 189sent up the control socket). 190