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ng_ksocket(4)

NAME

     ng_ksocket -- kernel socket netgraph node type

SYNOPSIS

     #include <netgraph/ng_ksocket.h>

DESCRIPTION

     A ksocket node is both a netgraph node and a BSD socket.  The ng_ksocket
     node type allows one to open a socket inside the kernel and have it
     appear as a Netgraph node.  The ng_ksocket node type is the reverse of
     the socket node type (see ng_socket(4)): whereas the socket node type
     enables the user-level manipulation (via a socket) of what is normally a
     kernel-level entity (the associated Netgraph node), the ng_ksocket node
     type enables the kernel-level manipulation (via a Netgraph node) of what
     is normally a user-level entity (the associated socket).

     A ng_ksocket node allows at most one hook connection.  Connecting to the
     node is equivalent to opening the associated socket.  The name given to
     the hook determines what kind of socket the node will open (see below).
     When the hook is disconnected and/or the node is shutdown, the associated
     socket is closed.

HOOKS

     This node type supports a single hook connection at a time.  The name of
     the hook must be of the form <family>/<type>/<proto>, where the family,
     type, and proto are the decimal equivalent of the same arguments to
     socket(2).  Alternately, aliases for the commonly used values are
     accepted as well.	For example inet/dgram/udp is a more readable but
     equivalent version of 2/2/17.

     Data received into socket is sent out via hook.  Data received on hook is
     sent out from socket, if the latter is connected (an NGM_KSOCKET_CONNECT
     was sent to node before).	If socket is not connected, destination struct
     sockaddr must be supplied in an mbuf tag with cookie NGM_KSOCKET_COOKIE
     and type NG_KSOCKET_TAG_SOCKADDR attached to data.  Otherwise ng_ksocket
     will return ENOTCONN to sender.

CONTROL MESSAGES

     This node type supports the generic control messages, plus the following:

     NGM_KSOCKET_BIND
	  This functions exactly like the bind(2) system call.	The struct
	  sockaddr socket address parameter should be supplied as an argument.

     NGM_KSOCKET_LISTEN
	  This functions exactly like the listen(2) system call.  The backlog
	  parameter (a single 32 bit int) should be supplied as an argument.

     NGM_KSOCKET_CONNECT
	  This functions exactly like the connect(2) system call.  The struct
	  sockaddr destination address parameter should be supplied as an
	  argument.

     NGM_KSOCKET_ACCEPT
	  Currently unimplemented.

     NGM_KSOCKET_GETNAME

	  Equivalent to the setsockopt(2) system call, except that the option
	  name, level, and value are passed in a struct ng_ksocket_sockopt.

     NGM_KSOCKET_GETOPT
	  Equivalent to the getsockopt(2) system call, except that the option
	  is passed in a struct ng_ksocket_sockopt.  When sending this com-
	  mand, the value field should be empty; upon return, it will contain
	  the retrieved value.

ASCII FORM CONTROL MESSAGES

     For control messages that pass a struct sockaddr in the argument field,
     the normal ASCII equivalent of the C structure is an acceptable form.
     For the PF_INET and PF_LOCAL address families, a more convenient form is
     also used, which is the protocol family name, followed by a slash, fol-
     lowed by the actual address.  For PF_INET, the address is an IP address
     followed by an optional colon and port number.  For PF_LOCAL, the address
     is the pathname as a doubly quoted string.

     Examples:

     PF_LOCAL	 local/"/tmp/foo.socket"

     PF_INET	 inet/192.168.1.1:1234

     Other	 { family=16 len=16 data=[0x70 0x00 0x01 0x23] }

     For control messages that pass a struct ng_ksocket_sockopt, the normal
     ASCII form for that structure is used.  In the future, more convenient
     encoding of the more common socket options may be supported.

SHUTDOWN

     This node shuts down upon receipt of a NGM_SHUTDOWN control message, or
     when the hook is disconnected.  Shutdown of the node closes the associ-
     ated socket.

SEE ALSO

     socket(2), netgraph(4), ng_socket(4), ngctl(8), mbuf_tags(9)

HISTORY

     The ng_ksocket node type was implemented in FreeBSD 4.0.

AUTHORS

     Archie Cobbs <archie@FreeBSD.org>

FreeBSD 5.4			 June 8, 2004			   FreeBSD 5.4

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