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Author: Archie Cobbs <archie@whistle.com>
$FreeBSD: head/share/man/man4/ng_socket.4 52419 1999-10-21 09:06:11Z julian $
$Whistle: ng_socket.8,v 1.5 1999/01/25 23:46:27 archie Exp $
.Dd January 19, 1999 .Dt NG_SOCKET 8 .Os FreeBSD 3 .Sh NAME .Nm ng_socket .Nd netgraph socket node type .Sh SYNOPSIS .Fd #include <netgraph/ng_message.h> .Fd #include <netgraph/ng_socket.h> .Sh DESCRIPTION A .Nm socket node is both a BSD socket and a netgraph node. The .Nm socket node type allows user-mode processes to participate in the kernel .Xr netgraph 4 networking subsystem using the BSD socket interface.
p A new .Nm socket node is created by creating a new socket of type .Dv NG_CONTROL in the protocol family .Dv PF_NETGRAPH , using the .Xr socket 2 system call. Any control messages received by the node are received using .Xr recvfrom 2 ; the socket address argument is a .Dv "struct sockaddr_ng" containing the sender's netgraph address. Conversely, control messages can be sent to any node by calling .Xr sendto 2 , supplying the recipient's address in a .Dv "struct sockaddr_ng" . The .Xr bind 2 system call may be used to assign a global netgraph name to the node.
p To transmit and receive netgraph data packets, a .Dv NG_DATA socket must also be created using .Xr socket 2 and associated with a .Nm socket node. .Dv NG_DATA sockets do not automatically have nodes associated with them; they are bound to a specific node via the .Xr connect 2 system call. The address argument is the netgraph address of the .Nm socket node already created. Once a data socket is associated with a node, any data packets received by the node are read using .Xr recvfrom 2 and any packets to be sent out from the node are written using .Xr sendto 2 . In the case of data sockets, the .Dv "struct sockaddr_ng" contains the name of the .Em hook on which the data was received or should be sent.
p There is a user library that simplifies using netgraph sockets; see .Xr netgraph 3 . .Sh HOOKS This node type supports hooks with arbitrary names (as long as they are unique) and always accepts hook connection requests. .Sh CONTROL MESSAGES This node type supports only the generic control messages. .Sh SHUTDOWN This node type shuts down and disappears when both the associated .Dv NG_CONTROL and .Dv NG_DATA sockets have been closed, or a .Dv NGM_SHUTDOWN control message is received. In the latter case, attempts to write to the still-open sockets will return .Er ENOTCONN . .Sh BUGS It is not possible to reject the connection of a hook, though any data received on that hook can certainly be ignored. .Sh SEE ALSO .Xr socket 2 , .Xr netgraph 3 , .Xr netgraph 4 , .Xr ngctl 8 . .Sh AUTHOR Julian Elisher <julian@whistle.com>