1999-10-21 09:06:11 +00:00
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.\" 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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.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
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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: ng_socket.8,v 1.5 1999/01/25 23:46:27 archie Exp $
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.\"
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.Dd January 19, 1999
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.Dt NG_SOCKET 8
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.Os FreeBSD 3
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.Sh NAME
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.Nm ng_socket
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.Nd netgraph socket node type
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.Sh SYNOPSIS
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.Fd #include <netgraph/ng_message.h>
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.Fd #include <netgraph/ng_socket.h>
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.Sh DESCRIPTION
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A
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.Nm socket
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node is both a BSD socket and a netgraph node. The
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.Nm socket
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node type allows user-mode processes to participate in the kernel
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.Xr netgraph 4
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networking subsystem using the BSD socket interface.
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.Pp
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A new
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.Nm socket
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node is created by creating a new socket of type
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.Dv NG_CONTROL
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in the protocol family
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.Dv PF_NETGRAPH ,
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using the
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.Xr socket 2
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system call.
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Any control messages received by the node are received using
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.Xr recvfrom 2 ;
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the socket address argument is a
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.Dv "struct sockaddr_ng"
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containing the sender's netgraph address. Conversely, control messages
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can be sent to any node by calling
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.Xr sendto 2 ,
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supplying the recipient's address in a
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.Dv "struct sockaddr_ng" .
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The
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.Xr bind 2
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system call may be used to assign a global netgraph name to the node.
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.Pp
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To transmit and receive netgraph data packets, a
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.Dv NG_DATA
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socket must also be created using
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.Xr socket 2
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and associated with a
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.Nm socket
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node.
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.Dv NG_DATA sockets do not automatically
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have nodes associated with them; they are bound to a specific node via the
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.Xr connect 2
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system call. The address argument is the netgraph address of the
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.Nm socket
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node already created. Once a data socket is associated with a node,
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any data packets received by the node are read using
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.Xr recvfrom 2
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and any packets to be sent out from the node are written using
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.Xr sendto 2 .
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In the case of data sockets, the
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.Dv "struct sockaddr_ng"
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contains the name of the
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.Em hook
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on which the data was received or should be sent.
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.Pp
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There is a user library that simplifies using netgraph sockets; see
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.Xr netgraph 3 .
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.Sh HOOKS
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This node type supports hooks with arbitrary names (as long as
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they are unique) and always accepts hook connection requests.
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.Sh CONTROL MESSAGES
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This node type supports only the generic control messages.
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.Sh SHUTDOWN
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This node type shuts down and disappears when both the associated
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.Dv NG_CONTROL
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and
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.Dv NG_DATA
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sockets have been closed, or a
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.Dv NGM_SHUTDOWN
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control message is received. In the latter case, attempts to write
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to the still-open sockets will return
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.Er ENOTCONN .
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.Sh BUGS
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It is not possible to reject the connection of a hook, though any
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data received on that hook can certainly be ignored.
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.Sh SEE ALSO
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.Xr socket 2 ,
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.Xr netgraph 3 ,
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.Xr netgraph 4 ,
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.Xr ngctl 8 .
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.Sh AUTHOR
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1999-10-30 20:30:19 +00:00
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Julian Elischer <julian@whistle.com>
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