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122 lines
3.4 KiB
Groff
122 lines
3.4 KiB
Groff
.\" Copyright (c) 2002 Mark Santcroos <marks@ripe.net>
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd June 15, 2002
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.Dt NG_DEVICE 4
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.Os
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.Sh NAME
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.Nm ng_device
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.Nd device netgraph node type
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.Sh SYNOPSIS
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.In netgraph/ng_device.h
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.Sh DESCRIPTION
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A
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.Nm device
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node is both a netgraph node and a system device interface.
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When a
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.Nm device
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node is created, a new device entry appears which is accessible via the
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regular file operators such as
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.Xr open 2 ,
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.Xr close 2 ,
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.Xr read 2 ,
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.Xr write 2 ,
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etc.
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.Pp
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The first node is created as
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.Pa /dev/ngd0 ,
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all subsequent nodes
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.Pa /dev/ngd1 , /dev/ngd2 ,
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etc.
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The only way a
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.Nm device
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node can be created is by a connection to the main
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.Nm device
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node by another type of
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.Xr netgraph 4
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node.
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.Pp
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When a node is shut down, the corresponding device is removed
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and the device name becomes available for reuse by future
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.Nm device
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nodes.
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.Pp
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A
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.Nm device
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node has a single hook to which it connects to the requesting
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.Xr netgraph 4
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node.
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All data coming in over the hook will be presented to the device
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for
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.Xr read 2 .
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All data coming in from the device entry by
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.Xr write 2
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will be forwarded to the hook.
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.Sh HOOKS
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The
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.Nm device
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node has no named hooks.
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There is one hook which is used for all interactions.
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This is the hook created by the calling node.
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.Sh CONTROL MESSAGES
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The
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.Nm device
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node supports no special control messages.
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All incoming messages from the
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hook will be returned to the sender.
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Additionally the node accepts
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.Xr ioctl 2 Ns s
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from the device entry.
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These will be encapsulated into
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.Xr netgraph 4
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messages and send out to the hook.
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.Sh SHUTDOWN
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This node shuts down upon receipt of a
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.Dv NGM_SHUTDOWN
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control message.
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The associated interface is removed and becomes available
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for use by future
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.Nm device
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nodes.
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.Pp
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Unlike most other node types, a
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.Nm device
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node does
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.Em not
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go away when all hooks have been disconnected; rather, an explicit
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.Dv NGM_SHUTDOWN
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control message is required.
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.Sh SEE ALSO
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.Xr netgraph 4 ,
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.Xr ngctl 8
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.Sh HISTORY
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The
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.Nm device
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node type was first implemented in
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.Fx 5.0 .
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.Sh AUTHORS
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.An Mark Santcroos Aq marks@ripe.net
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