327 lines
9.4 KiB
Groff
327 lines
9.4 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 19, 1999
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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 NgRecvMsg ,
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.Nm NgSendData ,
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.Nm NgRecvData ,
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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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.Fn NgSendMsg "int cs" "const char *path" "int cookie" "int cmd" "const void *arg" "size_t arglen"
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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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.Fn NgSendMsgReply "int cs" "const char *path" "struct ng_mesg *msg" "const void *arg" "size_t arglen"
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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 NgRecvAsciiMsg "int cs" "struct ng_mesg *rep" "size_t replen" "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 NgSetDebug "int level"
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.Ft void
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.Fn NgSetErrLog "void (*log)(const char *fmt, ...)" "void (*logx)(const char *fmt, ...)"
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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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.Em 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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.Em socket
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type netgraph node with associated control and data sockets. If
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.Fa name
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is non-NULL, 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 NULL if only one socket is desired.
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The
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.Fn NgMkSockNode
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function loads the socket node type KLD if it's 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 socket node associated
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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 ,
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.Fa 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. 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. 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 non-NULL, it must point to a buffer of at least
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.Dv "NG_PATHLEN + 1"
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bytes, which will be filled in (and NUL 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 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. The result is the same as
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.Fn NgRecvAsciiMsg ,
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with the exception that the reply arguments field will contain
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a NUL-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 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. If
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.Fa "hook"
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is non-NULL, it must point to a buffer of at least
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.Dv "NG_HOOKLEN + 1"
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bytes, which will be filled in (and NUL 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 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. 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. 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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.Dv -lnetgraph
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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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.Dq 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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The
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.Fn NgSetErrLog
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function has no return value.
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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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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@whistle.com
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