/*
 * Copyright (c) 1982, 1986 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 *	@(#)unpcb.h	7.3 (Berkeley) 6/27/88
 */

/*
 * Protocol control block for an active
 * instance of a UNIX internal protocol.
 *
 * A socket may be associated with an inode in the
 * file system.  If so, the unp_inode pointer holds
 * a reference count to this inode, which should be irele'd
 * when the socket goes away.
 *
 * A socket may be connected to another socket, in which
 * case the control block of the socket to which it is connected
 * is given by unp_conn.
 *
 * A socket may be referenced by a number of sockets (e.g. several
 * sockets may be connected to a datagram socket.)  These sockets
 * are in a linked list starting with unp_refs, linked through
 * unp_nextref and null-terminated.  Note that a socket may be referenced
 * by a number of other sockets and may also reference a socket (not
 * necessarily one which is referencing it).  This generates
 * the need for unp_refs and unp_nextref to be separate fields.
 *
 * Stream sockets keep copies of receive sockbuf sb_cc and sb_mbcnt
 * so that changes in the sockbuf may be computed to modify
 * back pressure on the sender accordingly.
 */
struct	unpcb {
	struct	socket *unp_socket;	/* pointer back to socket */
	struct	inode *unp_inode;	/* if associated with file */
	ino_t	unp_ino;		/* fake inode number */
	struct	unpcb *unp_conn;	/* control block of connected socket */
	struct	unpcb *unp_refs;	/* referencing socket linked list */
	struct 	unpcb *unp_nextref;	/* link in unp_refs list */
	struct	mbuf *unp_addr;		/* bound address of socket */
	int	unp_cc;			/* copy of rcv.sb_cc */
	int	unp_mbcnt;		/* copy of rcv.sb_mbcnt */
};

#define	sotounpcb(so)	((struct unpcb *)((so)->so_pcb))
