A
ksocket
node is both a netgraph node and a
BSD socket.
The
node type allows one to open a socket inside the kernel and have
it appear as a Netgraph node.
The
node type is the reverse of the socket node type (see
ng_socket4):
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
node type enables the kernel-level manipulation (via a Netgraph node) of
what is normally a user-level entity (the associated socket).
A
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
familytype
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
Vt struct sockaddr
must be supplied in an mbuf tag with cookie
NGM_KSOCKET_COOKIE
and type
NG_KSOCKET_TAG_SOCKADDR
attached to data.
Otherwise
will return
Er 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
Vt 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
Vt 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
Vt 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
Vt 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
Vt 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
Vt struct ng_ksocket_sockopt .
NGM_KSOCKET_GETOPT
Equivalent to the
getsockopt(2)
system call, except that the option is passed in a
Vt struct ng_ksocket_sockopt .
When sending this command, the
value
field should be empty; upon return, it will contain the
retrieved value.
ASCII FORM CONTROL MESSAGES
For control messages that pass a
Vt 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
Vt 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.
