32889325b8
much more apt to note that it has the same result as NgRecvMsg. Make the manual page less circular in its reference to this fact.
399 lines
11 KiB
Groff
399 lines
11 KiB
Groff
.\" Copyright (c) 1996-1999 Whistle Communications, Inc.
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.\" All rights reserved.
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.\"
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.\" Subject to the following obligations and disclaimer of warranty, use and
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.\" redistribution of this software, in source or object code forms, with or
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.\" without modifications are expressly permitted by Whistle Communications;
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.\" provided, however, that:
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.\" 1. Any and all reproductions of the source or object code must include the
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.\" copyright notice above and the following disclaimer of warranties; and
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.\" 2. No rights are granted, in any manner or form, to use Whistle
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.\" Communications, Inc. trademarks, including the mark "WHISTLE
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.\" COMMUNICATIONS" on advertising, endorsements, or otherwise except as
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.\" such appears in the above copyright notice or in the software.
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.\"
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.\" THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
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.\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
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.\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
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.\" INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
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.\" WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
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.\" REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
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.\" SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
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.\" IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
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.\" RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
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.\" WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
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.\" PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
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.\" SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER 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 WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
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.\" OF SUCH DAMAGE.
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.\"
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.\" Author: Archie Cobbs <archie@whistle.com>
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.\"
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.\" $FreeBSD$
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.\" $Whistle: netgraph.3,v 1.7 1999/01/25 07:14:06 archie Exp $
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.\"
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.Dd January 27, 2004
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.Dt NETGRAPH 3
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.Os
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.Sh NAME
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.Nm NgMkSockNode ,
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.Nm NgNameNode ,
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.Nm NgSendMsg ,
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.Nm NgSendAsciiMsg ,
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.Nm NgSendMsgReply ,
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.Nm NgRecvMsg ,
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.Nm NgAllocRecvMsg ,
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.Nm NgRecvAsciiMsg ,
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.Nm NgAllocRecvAsciiMsg ,
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.Nm NgSendData ,
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.Nm NgRecvData ,
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.Nm NgAllocRecvData ,
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.Nm NgSetDebug ,
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.Nm NgSetErrLog
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.Nd netgraph user library
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.Sh LIBRARY
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.Lb libnetgraph
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.Sh SYNOPSIS
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.In netgraph.h
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.Ft int
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.Fn NgMkSockNode "const char *name" "int *csp" "int *dsp"
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.Ft int
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.Fn NgNameNode "int cs" "const char *path" "const char *fmt" ...
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.Ft int
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.Fo NgSendMsg
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.Fa "int cs" "const char *path" "int cookie" "int cmd" "const void *arg"
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.Fa "size_t arglen"
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.Fc
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.Ft int
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.Fn NgSendAsciiMsg "int cs" "const char *path" "const char *fmt" ...
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.Ft int
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.Fo NgSendMsgReply
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.Fa "int cs" "const char *path" "struct ng_mesg *msg" "const void *arg"
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.Fa "size_t arglen"
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.Fc
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.Ft int
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.Fn NgRecvMsg "int cs" "struct ng_mesg *rep" "size_t replen" "char *path"
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.Ft int
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.Fn NgAllocRecvMsg "int cs" "struct ng_mesg **rep" "char *path"
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.Ft int
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.Fn NgRecvAsciiMsg "int cs" "struct ng_mesg *rep" "size_t replen" "char *path"
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.Ft int
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.Fn NgAllocRecvAsciiMsg "int cs" "struct ng_mesg **rep" "char *path"
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.Ft int
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.Fn NgSendData "int ds" "const char *hook" "const u_char *buf" "size_t len"
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.Ft int
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.Fn NgRecvData "int ds" "u_char *buf" "size_t len" "char *hook"
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.Ft int
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.Fn NgAllocRecvData "int ds" "u_char **buf" "char *hook"
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.Ft int
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.Fn NgSetDebug "int level"
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.Ft void
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.Fo NgSetErrLog
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.Fa "void \*[lp]*log\*[rp]\*[lp]const char *fmt, ...\*[rp]"
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.Fa "void \*[lp]*logx\*[rp]\*[lp]const char *fmt, ...\*[rp]"
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.Fc
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.Sh DESCRIPTION
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These functions facilitate user-mode program participation in the kernel
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.Xr netgraph 4
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graph-based networking system, by utilizing the netgraph
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.Vt socket
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node type (see
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.Xr ng_socket 4 ) .
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.Pp
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The
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.Fn NgMkSockNode
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function should be called first, to create a new
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.Vt socket
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type netgraph node with associated control and data sockets.
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If
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.Fa name
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is
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.No non- Ns Dv NULL ,
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the node will have that global name assigned to it.
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The
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.Fa csp
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and
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.Fa dsp
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arguments will be set to the newly opened control and data sockets
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associated with the node; either
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.Fa csp
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or
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.Fa dsp
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may be
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.Dv NULL
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if only one socket is desired.
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The
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.Fn NgMkSockNode
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function loads the
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.Vt socket
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node type KLD if it is not already loaded.
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.Pp
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The
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.Fn NgNameNode
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function assigns a global name to the node addressed by
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.Fa path .
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.Pp
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The
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.Fn NgSendMsg
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function sends a binary control message from the
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.Vt socket
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node associated with control socket
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.Fa cs
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to the node addressed by
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.Fa path .
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The
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.Fa cookie
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indicates how to interpret
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.Fa cmd ,
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which indicates a specific command.
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Extra argument data (if any) is specified by
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.Fa arg
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and
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.Fa arglen .
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The
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.Fa cookie , cmd ,
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and argument data are defined by the header file corresponding
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to the type of the node being addressed.
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The unique, non-negative token value chosen for use in the message
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header is returned.
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This value is typically used to associate replies.
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.Pp
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Use
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.Fn NgSendMsgReply
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to send reply to a previously received control message.
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The original message header should be pointed to by
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.Fa msg .
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.Pp
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The
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.Fn NgSendAsciiMsg
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function performs the same function as
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.Fn NgSendMsg ,
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but adds support for
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.Tn ASCII
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encoding of control messages.
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The
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.Fn NgSendAsciiMsg
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function formats its input a la
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.Xr printf 3
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and then sends the resulting
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.Tn ASCII
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string to the node in a
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.Dv NGM_ASCII2BINARY
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control message.
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The node returns a binary version of the
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message, which is then sent back to the node just as with
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.Fn NgSendMsg .
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As with
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.Fn NgSendMsg ,
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the message token value is returned.
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Note that
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.Tn ASCII
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conversion may not be supported by all node types.
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.Pp
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The
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.Fn NgRecvMsg
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function reads the next control message received by the node associated with
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control socket
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.Fa cs .
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The message and any extra argument data must fit in
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.Fa replen
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bytes.
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If
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.Fa path
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is
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.No non- Ns Dv NULL ,
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it must point to a buffer of at least
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.Dv NG_PATHSIZ
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bytes, which will be filled in (and
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.Dv NUL
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terminated) with the path to
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the node from which the message was received.
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.Pp
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The length of the control message is returned.
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A return value of zero indicates that the socket was closed.
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.Pp
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The
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.Fn NgAllocRecvMsg
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function works exactly like
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.Fn NgRecvMsg ,
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except that the buffer for a message is dynamically allocated
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to guarantee that a message is not truncated.
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The size of the buffer is equal to the socket's receive buffer size.
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The caller is responsible for freeing the buffer when it is no longer required.
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.Pp
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The
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.Fn NgRecvAsciiMsg
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function works exactly like
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.Fn NgRecvMsg ,
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except that after the message is received, any binary arguments
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are converted to
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.Tn ASCII
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by sending a
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.Dv NGM_BINARY2ASCII
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request back to the originating node.
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The result is the same as
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.Fn NgRecvMsg ,
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with the exception that the reply arguments field will contain a
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.Dv NUL Ns -terminated
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.Tn ASCII
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version of the arguments (and the reply
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header argument length field will be adjusted).
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.Pp
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The
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.Fn NgAllocRecvAsciiMsg
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function works exactly like
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.Fn NgRecvAsciiMsg ,
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except that the buffer for a message is dynamically allocated
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to guarantee that a message is not truncated.
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The size of the buffer is equal to the socket's receive buffer size.
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The caller is responsible for freeing the buffer when it is no longer required.
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.Pp
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The
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.Fn NgSendData
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function writes a data packet out on the specified hook of the node
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corresponding to data socket
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.Fa ds .
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The node must already be connected to some other node via that hook.
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.Pp
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The
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.Fn NgRecvData
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function reads the next data packet (of up to
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.Fa len
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bytes) received by the node corresponding to data socket
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.Fa ds
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and stores it in
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.Fa buf ,
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which must be large enough to hold the entire packet.
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If
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.Fa hook
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is
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.No non- Ns Dv NULL ,
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it must point to a buffer of at least
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.Dv NG_HOOKSIZ
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bytes, which will be filled in (and
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.Dv NUL
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terminated) with the name of
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the hook on which the data was received.
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.Pp
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The length of the packet is returned.
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A return value of zero indicates that the socket was closed.
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.Pp
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The
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.Fn NgAllocRecvData
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function works exactly like
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.Fn NgRecvData ,
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except that the buffer for a data packet is dynamically allocated
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to guarantee that a data packet is not truncated.
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The size of the buffer is equal to the socket's receive buffer size.
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The caller is responsible for freeing the buffer when it is no longer required.
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.Pp
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The
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.Fn NgSetDebug
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and
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.Fn NgSetErrLog
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functions are used for debugging.
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The
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.Fn NgSetDebug
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function sets the debug level (if non-negative), and returns the old setting.
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Higher debug levels result in more verbosity.
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The default is zero.
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All debug and error messages are logged via the functions
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specified in the most recent call to
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.Fn NgSetErrLog .
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The default logging functions are
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.Xr vwarn 3
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and
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.Xr vwarnx 3 .
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.Pp
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At debug level 3, the library attempts to display control message arguments
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in
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.Tn ASCII
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format; however, this results in additional messages being
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sent which may interfere with debugging.
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At even higher levels,
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even these additional messages will be displayed, etc.
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.Pp
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Note that
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.Xr select 2
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can be used on the data and the control sockets to detect the presence of
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incoming data and control messages, respectively.
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Data and control packets are always written and read atomically, i.e.,
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in one whole piece.
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.Pp
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User mode programs must be linked with the
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.Fl l Ns Li netgraph
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flag to link in this library.
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.Sh INITIALIZATION
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To enable netgraph in your kernel, either your kernel must be
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compiled with
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.Cd "options NETGRAPH"
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in the kernel configuration
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file, or else the
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.Xr netgraph 4
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and
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.Xr ng_socket 4
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KLD modules must have been loaded via
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.Xr kldload 8 .
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.Sh RETURN VALUES
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The
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.Fn NgSetDebug
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function returns the previous debug setting.
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.Pp
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The
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.Fn NgSetErrLog
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function has no return value.
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.Pp
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All other functions return \-1 if there was an error and set
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.Va errno
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accordingly.
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.Pp
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A return value of zero from
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.Fn NgRecvMsg
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or
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.Fn NgRecvData
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indicates that the netgraph socket has been closed.
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.Pp
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For
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.Fn NgSendAsciiMsg
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and
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.Fn NgRecvAsciiMsg ,
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the following additional errors are possible:
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.Bl -tag -width Er
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.It Bq Er ENOSYS
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The node type does not know how to encode or decode the control message.
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.It Bq Er ERANGE
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The encoded or decoded arguments were too long for the supplied buffer.
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.It Bq Er ENOENT
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An unknown structure field was seen in an
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.Tn ASCII
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control message.
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.It Bq Er EALREADY
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The same structure field was specified twice in an
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.Tn ASCII
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control message.
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.It Bq Er EINVAL
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.Tn ASCII
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control message parse error or illegal value.
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.It Bq Er E2BIG
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ASCII control message array or fixed width string buffer overflow.
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.El
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.Sh SEE ALSO
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.Xr select 2 ,
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.Xr socket 2 ,
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.Xr warnx 3 ,
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.Xr kld 4 ,
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.Xr netgraph 4 ,
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.Xr ng_socket 4
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.Sh HISTORY
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The
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.Nm netgraph
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system was designed and first implemented at Whistle Communications, Inc.\& in
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a version of
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.Fx 2.2
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customized for the Whistle InterJet.
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.Sh AUTHORS
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.An "Archie Cobbs" Aq archie@FreeBSD.org
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