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 (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 argument.

       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 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 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.

       Setting socket options example:

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

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>

Debian                                           January 9, 2012                                   NG_KSOCKET(4)