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NG_KSOCKET(4)	       FreeBSD Kernel Interfaces Manual		 NG_KSOCKET(4)

     ng_ksocket	-- kernel socket netgraph node type

     #include <sys/types.h>
     #include <netgraph/ng_ksocket.h>

     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 ap-
     pear 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 en-
     ables the kernel-level manipulation (via a	Netgraph node) of what is nor-
     mally 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.

     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 ac-
     cepted as well.  For example inet/dgram/udp is a more readable but	equiv-
     alent 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.

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

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

     NGM_KSOCKET_ACCEPT	(accept)
	  Equivalent to	the accept(2) system call on a non-blocking socket.
	  If there is a	pending	connection on the queue, a new socket and a
	  corresponding	cloned node are	created.  Returned are the cloned
	  node's ID and	a peer name (as	struct sockaddr).  If there are	no
	  pending connections, this control message returns nothing, and a
	  connected node will receive the above	message	asynchronously,	when a
	  connection is	established.

	  A cloned node	supports a single hook with an arbitrary name.	If not
	  connected, a node disappears when its	parent node is destroyed.
	  Once connected, it becomes an	independent node.

     NGM_KSOCKET_GETNAME (getname)
	  Equivalent to	the getsockname(2) system call.	 The name is returned
	  as a struct sockaddr in the arguments	field of the reply.

     NGM_KSOCKET_GETPEERNAME (getpeername)
	  Equivalent to	the getpeername(2) system call.	 The name is returned
	  as a struct sockaddr in the arguments	field of the reply.

     NGM_KSOCKET_SETOPT	(setopt)
	  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	(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.

     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.


     PF_LOCAL  local/"/tmp/foo.socket"

     PF_INET   inet/

     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.

     Setting socket options example:

     Set FIB 2 for a socket (SOL_SOCKET, SO_SETFIB):
	       setopt {	level=0xffff name=0x1014 data=[	2 ] }

     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.

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

     The ng_ksocket node type was implemented in FreeBSD 4.0.

     Archie Cobbs <>

FreeBSD	13.0			January	9, 2012			  FreeBSD 13.0


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