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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@whistle.com> 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 8 40.Os FreeBSD 41.Sh NAME 42.Nm ng_socket 43.Nd netgraph socket node type 44.Sh SYNOPSIS 45.Fd #include <netgraph/ng_message.h> 46.Fd #include <netgraph/ng_socket.h> 47.Sh DESCRIPTION 48A 49.Nm socket 50node is both a BSD socket and a netgraph node. The 51.Nm 52node type allows user-mode processes to participate in the kernel 53.Xr netgraph 4 54networking subsystem using the BSD socket interface. The process must have 55root privileges to be able to create netgraph sockets however once created, 56any process that has one may use it. 57.Pp 58A new 59.Nm 60node is created by creating a new socket of type 61.Dv NG_CONTROL 62in the protocol family 63.Dv PF_NETGRAPH , 64using the 65.Xr socket 2 66system call. 67Any control messages received by the node 68and not having a cookie value of 69.Dv NGM_SOCKET_COOKIE 70are received by the process, using 71.Xr recvfrom 2 ; 72the socket address argument is a 73.Dv "struct sockaddr_ng" 74containing the sender's netgraph address. Conversely, control messages 75can be sent to any node by calling 76.Xr sendto 2 , 77supplying the recipient's address in a 78.Dv "struct sockaddr_ng" . 79The 80.Xr bind 2 81system call may be used to assign a global netgraph name to the node. 82.Pp 83To transmit and receive netgraph data packets, a 84.Dv NG_DATA 85socket must also be created using 86.Xr socket 2 87and associated with a 88.Nm 89node. 90.Dv NG_DATA sockets do not automatically 91have nodes associated with them; they are bound to a specific node via the 92.Xr connect 2 93system call. The address argument is the netgraph address of the 94.Nm 95node already created. Once a data socket is associated with a node, 96any data packets received by the node are read using 97.Xr recvfrom 2 98and any packets to be sent out from the node are written using 99.Xr sendto 2 . 100In the case of data sockets, the 101.Dv "struct sockaddr_ng" 102contains the name of the 103.Em hook 104on which the data was received or should be sent. 105.Pp 106As a special case, to allow netgraph data sockets to be used as stdin or stdout 107on naive programs, a 108.Xr sendto 2 109with a NULL sockaddr pointer, a 110.Xr send 2 111or a 112.Xr write 2 113will succeed in the case where there is exactly ONE hook attached to 114the socket node, (and thus the path is unambiguous). 115.Pp 116There is a user library that simplifies using netgraph sockets; see 117.Xr netgraph 3 . 118.Sh HOOKS 119This node type supports hooks with arbitrary names (as long as 120they are unique) and always accepts hook connection requests. 121.Sh CONTROL MESSAGES 122This node type supports the generic control messages, plus the following: 123.Bl -tag -width foo 124.It Dv NGM_SOCK_CMD_NOLINGER 125When the last hook is removed from this node, it will shut down as 126if it had received a 127.Dv NGM_SHUTDOWN 128message. Attempts to access the sockets associated will return 129.Er ENOTCONN . 130.It Dv NGM_SOCK_CMD_LINGER 131This is the default mode. When the last hook is removed, the node will 132continue to exist, ready to accept new hooks until it 133is explicitly shut down. 134.El 135.Pp 136All other messages 137with neither the 138.Dv NGM_SOCKET_COOKIE 139or 140.Dv NGM_GENERIC_COOKIE 141will be passed unaltered up the 142.Dv NG_CONTROL 143socket. 144.Sh SHUTDOWN 145This node type shuts down and disappears when both the associated 146.Dv NG_CONTROL 147and 148.Dv NG_DATA 149sockets have been closed, or a 150.Dv NGM_SHUTDOWN 151control message is received. In the latter case, attempts to write 152to the still-open sockets will return 153.Er ENOTCONN . 154If the 155.Dv NGM_SOCK_CMD_NOLINGER 156message has been received, closure of the last hook will also initiate 157a shutdown of the node. 158.Sh BUGS 159It is not possible to reject the connection of a hook, though any 160data received on that hook can certainly be ignored. 161.Pp 162The controlling process is not notified of all events that an in-kernel node 163would be notified of, e.g. a new hook, or hook removal. We should define 164some node-initiated messages for this purpose (to be sent up the control 165socket). 166.Sh SEE ALSO 167.Xr socket 2 , 168.Xr netgraph 3 , 169.Xr netgraph 4 , 170.Xr ng_ksocket 8 , 171.Xr ngctl 8 . 172.Sh HISTORY 173The 174.Nm 175node type was implemented in 176.Fx 4.0 . 177.Sh AUTHORS 178.An Julian Elischer Aq julian@whistle.com 179