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/share/man/man4/ng_ksocket.4

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 33.\" Author: Archie Cobbs <archie@FreeBSD.org>
 34.\"
 35.\" $FreeBSD$
 36.\"
 37.Dd January 9, 2012
 38.Dt NG_KSOCKET 4
 39.Os
 40.Sh NAME
 41.Nm ng_ksocket
 42.Nd kernel socket netgraph node type
 43.Sh SYNOPSIS
 44.In sys/types.h
 45.In netgraph/ng_ksocket.h
 46.Sh DESCRIPTION
 47A
 48.Nm ksocket
 49node is both a netgraph node and a
 50.Bx
 51socket.
 52The
 53.Nm
 54node type allows one to open a socket inside the kernel and have
 55it appear as a Netgraph node.
 56The
 57.Nm
 58node type is the reverse of the socket node type (see
 59.Xr ng_socket 4 ) :
 60whereas the socket node type enables the user-level manipulation (via
 61a socket) of what is normally a kernel-level entity (the associated
 62Netgraph node), the
 63.Nm
 64node type enables the kernel-level manipulation (via a Netgraph node) of
 65what is normally a user-level entity (the associated socket).
 66.Pp
 67A
 68.Nm
 69node allows at most one hook connection.
 70Connecting to the node is
 71equivalent to opening the associated socket.
 72The name given to the hook
 73determines what kind of socket the node will open (see below).
 74When the hook is disconnected and/or the node is shutdown, the
 75associated socket is closed.
 76.Sh HOOKS
 77This node type supports a single hook connection at a time.
 78The name of the hook must be of the form
 79.Em <family>/<type>/<proto> ,
 80where the
 81.Em family ,
 82.Em type ,
 83and
 84.Em proto
 85are the decimal equivalent of the same arguments to
 86.Xr socket 2 .
 87Alternately, aliases for the commonly used values are accepted as
 88well.
 89For example
 90.Dv inet/dgram/udp
 91is a more readable but equivalent version of
 92.Dv 2/2/17 .
 93.Pp
 94Data received into socket is sent out via hook.
 95Data received on hook is sent out from socket, if the latter is
 96connected (an
 97.Dv NGM_KSOCKET_CONNECT
 98was sent to node before).
 99If socket is not connected, destination
100.Vt "struct sockaddr"
101must be supplied in an mbuf tag with cookie
102.Dv NGM_KSOCKET_COOKIE
103and type
104.Dv NG_KSOCKET_TAG_SOCKADDR
105attached to data.
106Otherwise
107.Nm
108will return
109.Er ENOTCONN
110to sender.
111.Sh CONTROL MESSAGES
112This node type supports the generic control messages, plus the following:
113.Bl -tag -width foo
114.It Dv NGM_KSOCKET_BIND
115This functions exactly like the
116.Xr bind 2
117system call.
118The
119.Vt "struct sockaddr"
120socket address parameter should be supplied as an argument.
121.It Dv NGM_KSOCKET_LISTEN
122This functions exactly like the
123.Xr listen 2
124system call.
125The backlog parameter (a single 32 bit
126.Dv int )
127should be supplied as an argument.
128.It Dv NGM_KSOCKET_CONNECT
129This functions exactly like the
130.Xr connect 2
131system call.
132The
133.Vt "struct sockaddr"
134destination address parameter should be supplied as an argument.
135.It Dv NGM_KSOCKET_ACCEPT
136Equivalent to the
137.Xr accept 2
138system call on a non-blocking socket.
139If there is a pending connection on the queue,
140a new socket and a corresponding cloned node are created.
141Returned are the cloned node's ID and a peer name (as
142.Vt "struct sockaddr" ) .
143If there are no pending connections,
144this control message returns nothing,
145and a connected node will receive the above message asynchronously,
146when a connection is established.
147.Pp
148A cloned node supports a single hook with an arbitrary name.
149If not connected, a node disappears when its parent node is destroyed.
150Once connected, it becomes an independent node.
151.It Dv NGM_KSOCKET_GETNAME
152Equivalent to the
153.Xr getsockname 2
154system call.
155The name is returned as a
156.Vt "struct sockaddr"
157in the arguments field of the reply.
158.It Dv NGM_KSOCKET_GETPEERNAME
159Equivalent to the
160.Xr getpeername 2
161system call.
162The name is returned as a
163.Vt "struct sockaddr"
164in the arguments field of the reply.
165.It Dv NGM_KSOCKET_SETOPT
166Equivalent to the
167.Xr setsockopt 2
168system call, except that the option name, level, and value are passed in a
169.Vt "struct ng_ksocket_sockopt" .
170.It Dv NGM_KSOCKET_GETOPT
171Equivalent to the
172.Xr getsockopt 2
173system call, except that the option is passed in a
174.Vt "struct ng_ksocket_sockopt" .
175When sending this command, the
176.Dv value
177field should be empty; upon return, it will contain the
178retrieved value.
179.El
180.Sh ASCII FORM CONTROL MESSAGES
181For control messages that pass a
182.Vt "struct sockaddr"
183in the argument field, the normal
184.Tn ASCII
185equivalent of the C structure
186is an acceptable form.
187For the
188.Dv PF_INET
189and
190.Dv PF_LOCAL
191address families, a more convenient form is also used, which is
192the protocol family name, followed by a slash, followed by the actual
193address.
194For
195.Dv PF_INET ,
196the address is an IP address followed by an optional colon and port number.
197For
198.Dv PF_LOCAL ,
199the address is the pathname as a doubly quoted string.
200.Pp
201Examples:
202.Bl -tag -width "PF_LOCAL"
203.It Dv PF_LOCAL
204local/"/tmp/foo.socket"
205.It Dv PF_INET
206inet/192.168.1.1:1234
207.It Other
208.Dv "\&{ family=16 len=16 data=[0x70 0x00 0x01 0x23] \&}"
209.El
210.Pp
211For control messages that pass a
212.Vt "struct ng_ksocket_sockopt" ,
213the normal
214.Tn ASCII
215form for that structure is used.
216In the future, more
217convenient encoding of the more common socket options may be supported.
218.Pp
219Setting socket options example:
220.Bl -tag -width "PF_LOCAL"
221.It Set FIB 2 for a socket (SOL_SOCKET, SO_SETFIB):
222.Dv "setopt \&{ level=0xffff name=0x1014 data=[ 2 ] \&}"
223.El
224.Sh SHUTDOWN
225This node shuts down upon receipt of a
226.Dv NGM_SHUTDOWN
227control message, or when the hook is disconnected.
228Shutdown of the node closes the associated socket.
229.Sh SEE ALSO
230.Xr socket 2 ,
231.Xr netgraph 4 ,
232.Xr ng_socket 4 ,
233.Xr ngctl 8 ,
234.Xr mbuf_tags 9 ,
235.Xr socket 9
236.Sh HISTORY
237The
238.Nm
239node type was implemented in
240.Fx 4.0 .
241.Sh AUTHORS
242.An Archie Cobbs Aq archie@FreeBSD.org