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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@FreeBSD.org> 34.\" $Whistle: ng_socket.8,v 1.5 1999/01/25 23:46:27 archie Exp $ 35.\" 36.Dd January 19, 1999 37.Dt NG_SOCKET 4 38.Os 39.Sh NAME 40.Nm ng_socket 41.Nd netgraph socket node type 42.Sh SYNOPSIS 43.In sys/types.h 44.In netgraph/ng_socket.h 45.Sh DESCRIPTION 46A 47.Nm socket 48node is both a 49.Bx 50socket and a netgraph node. 51The 52.Nm 53node type allows user-mode processes to participate in the kernel 54.Xr netgraph 4 55networking subsystem using the 56.Bx 57socket interface. 58The 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. 79Conversely, control messages can 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 95sockets do not automatically 96have nodes associated with them; they are bound to a specific node via the 97.Xr connect 2 98system call. 99The address argument is the netgraph address of the 100.Nm 101node already created. 102Once a data socket is associated with a node, 103any data packets received by the node are read using 104.Xr recvfrom 2 105and any packets to be sent out from the node are written using 106.Xr sendto 2 . 107In the case of data sockets, the 108.Dv "struct sockaddr_ng" 109contains the name of the 110.Em hook 111on which the data was received or should be sent. 112.Pp 113As a special case, to allow netgraph data sockets to be used as stdin or stdout 114on naive programs, a 115.Xr sendto 2 116with a NULL sockaddr pointer, a 117.Xr send 2 118or a 119.Xr write 2 120will succeed in the case where there is exactly ONE hook attached to 121the socket node, (and thus the path is unambiguous). 122.Pp 123There is a user library that simplifies using netgraph sockets; see 124.Xr netgraph 3 . 125.Sh HOOKS 126This node type supports hooks with arbitrary names (as long as 127they are unique) and always accepts hook connection requests. 128.Sh CONTROL MESSAGES 129This node type supports the generic control messages, plus the following: 130.Bl -tag -width foo 131.It Dv NGM_SOCK_CMD_NOLINGER 132When the last hook is removed from this node, it will shut down as 133if it had received a 134.Dv NGM_SHUTDOWN 135message. 136Attempts to access the sockets associated will return 137.Er ENOTCONN . 138.It Dv NGM_SOCK_CMD_LINGER 139This is the default mode. 140When the last hook is removed, the node will 141continue to exist, ready to accept new hooks until it 142is explicitly shut down. 143.El 144.Pp 145All other messages 146with neither the 147.Dv NGM_SOCKET_COOKIE 148or 149.Dv NGM_GENERIC_COOKIE 150will be passed unaltered up the 151.Dv NG_CONTROL 152socket. 153.Sh SHUTDOWN 154This node type shuts down and disappears when both the associated 155.Dv NG_CONTROL 156and 157.Dv NG_DATA 158sockets have been closed, or a 159.Dv NGM_SHUTDOWN 160control message is received. 161In the latter case, attempts to write 162to the still-open sockets will return 163.Er ENOTCONN . 164If the 165.Dv NGM_SOCK_CMD_NOLINGER 166message has been received, closure of the last hook will also initiate 167a shutdown of the node. 168.Sh SEE ALSO 169.Xr socket 2 , 170.Xr netgraph 3 , 171.Xr netgraph 4 , 172.Xr ng_ksocket 4 , 173.Xr ngctl 8 174.Sh HISTORY 175The 176.Nm 177node type was implemented in 178.Fx 4.0 . 179.Sh AUTHORS 180.An Julian Elischer Aq Mt julian@FreeBSD.org 181.Sh BUGS 182It is not possible to reject the connection of a hook, though any 183data received on that hook can certainly be ignored. 184.Pp 185The controlling process is not notified of all events that an in-kernel node 186would be notified of, e.g.\& a new hook, or hook removal. 187Some node-initiated messages should be defined for this purpose (to be 188sent up the control socket). 189