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 97sockets do not automatically 98have nodes associated with them; they are bound to a specific node via the 99.Xr connect 2 100system call. 101The address argument is the netgraph address of the 102.Nm 103node already created. 104Once a data socket is associated with a node, 105any data packets received by the node are read using 106.Xr recvfrom 2 107and any packets to be sent out from the node are written using 108.Xr sendto 2 . 109In the case of data sockets, the 110.Dv "struct sockaddr_ng" 111contains the name of the 112.Em hook 113on which the data was received or should be sent. 114.Pp 115As a special case, to allow netgraph data sockets to be used as stdin or stdout 116on naive programs, a 117.Xr sendto 2 118with a NULL sockaddr pointer, a 119.Xr send 2 120or a 121.Xr write 2 122will succeed in the case where there is exactly ONE hook attached to 123the socket node, (and thus the path is unambiguous). 124.Pp 125There is a user library that simplifies using netgraph sockets; see 126.Xr netgraph 3 . 127.Sh HOOKS 128This node type supports hooks with arbitrary names (as long as 129they are unique) and always accepts hook connection requests. 130.Sh CONTROL MESSAGES 131This node type supports the generic control messages, plus the following: 132.Bl -tag -width foo 133.It Dv NGM_SOCK_CMD_NOLINGER 134When the last hook is removed from this node, it will shut down as 135if it had received a 136.Dv NGM_SHUTDOWN 137message. 138Attempts to access the sockets associated will return 139.Er ENOTCONN . 140.It Dv NGM_SOCK_CMD_LINGER 141This is the default mode. 142When the last hook is removed, the node will 143continue to exist, ready to accept new hooks until it 144is explicitly shut down. 145.El 146.Pp 147All other messages 148with neither the 149.Dv NGM_SOCKET_COOKIE 150or 151.Dv NGM_GENERIC_COOKIE 152will be passed unaltered up the 153.Dv NG_CONTROL 154socket. 155.Sh SHUTDOWN 156This node type shuts down and disappears when both the associated 157.Dv NG_CONTROL 158and 159.Dv NG_DATA 160sockets have been closed, or a 161.Dv NGM_SHUTDOWN 162control message is received. 163In the latter case, attempts to write 164to the still-open sockets will return 165.Er ENOTCONN . 166If the 167.Dv NGM_SOCK_CMD_NOLINGER 168message has been received, closure of the last hook will also initiate 169a shutdown of the node. 170.Sh SEE ALSO 171.Xr socket 2 , 172.Xr netgraph 3 , 173.Xr netgraph 4 , 174.Xr ng_ksocket 4 , 175.Xr ngctl 8 176.Sh HISTORY 177The 178.Nm 179node type was implemented in 180.Fx 4.0 . 181.Sh AUTHORS 182.An Julian Elischer Aq Mt julian@FreeBSD.org 183.Sh BUGS 184It is not possible to reject the connection of a hook, though any 185data received on that hook can certainly be ignored. 186.Pp 187The controlling process is not notified of all events that an in-kernel node 188would be notified of, e.g.\& a new hook, or hook removal. 189Some node-initiated messages should be defined for this purpose (to be 190sent up the control socket). 191