NAME¶
ng_ksocket —
kernel socket netgraph
node type
SYNOPSIS¶
#include <sys/types.h>
#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
- 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
- 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
- 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
- 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 command, 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, followed 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 associated socket.
SEE ALSO¶
socket(2),
netgraph(4),
ng_socket(4),
ngctl(8),
mbuf_tags(9),
socket(9)
HISTORY¶
The
ng_ksocket node type was implemented in
FreeBSD 4.0.
AUTHORS¶
Archie Cobbs ⟨archie@FreeBSD.org⟩