slirp/mbuf.h

/*
 * Copyright (c) 1982, 1986, 1988, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)mbuf.h	8.3 (Berkeley) 1/21/94
 * mbuf.h,v 1.9 1994/11/14 13:54:20 bde Exp
 */

#ifndef _MBUF_H_
#define _MBUF_H_

#define MINCSIZE 4096	/* Amount to increase mbuf if too small */

/*
 * Macros for type conversion
 * mtod(m,t) -	convert mbuf pointer to data pointer of correct type
 */
#define mtod(m,t)	((t)(m)->m_data)

/* XXX About mbufs for slirp:
 * Only one mbuf is ever used in a chain, for each "cell" of data.
 * m_nextpkt points to the next packet, if fragmented.
 * If the data is too large, the M_EXT is used, and a larger block
 * is alloced.  Therefore, m_free[m] must check for M_EXT and if set
 * free the m_ext.  This is inefficient memory-wise, but who cares.
 */

/* XXX should union some of these! */
/* header at beginning of each mbuf: */
struct m_hdr {
	struct	mbuf *mh_next;		/* Linked list of mbufs */
	struct	mbuf *mh_prev;
	struct	mbuf *mh_nextpkt;	/* Next packet in queue/record */
	struct	mbuf *mh_prevpkt; /* Flags aren't used in the output queue */
	int	mh_flags;	  /* Misc flags */

	int	mh_size;		/* Size of data */
	struct	socket *mh_so;

	caddr_t	mh_data;		/* Location of data */
	int	mh_len;			/* Amount of data in this mbuf */
};

/*
 * How much room is in the mbuf, from m_data to the end of the mbuf
 */
#define M_ROOM(m) ((m->m_flags & M_EXT)? \
			(((m)->m_ext + (m)->m_size) - (m)->m_data) \
		   : \
			(((m)->m_dat + (m)->m_size) - (m)->m_data))

/*
 * How much free room there is
 */
#define M_FREEROOM(m) (M_ROOM(m) - (m)->m_len)
#define M_TRAILINGSPACE M_FREEROOM

struct mbuf {
	struct	m_hdr m_hdr;
	Slirp *slirp;
	union M_dat {
		char	m_dat_[1]; /* ANSI don't like 0 sized arrays */
		char	*m_ext_;
	} M_dat;
};

#define m_next		m_hdr.mh_next
#define m_prev		m_hdr.mh_prev
#define m_nextpkt	m_hdr.mh_nextpkt
#define m_prevpkt	m_hdr.mh_prevpkt
#define m_flags		m_hdr.mh_flags
#define	m_len		m_hdr.mh_len
#define	m_data		m_hdr.mh_data
#define m_size		m_hdr.mh_size
#define m_dat		M_dat.m_dat_
#define m_ext		M_dat.m_ext_
#define m_so		m_hdr.mh_so

#define ifq_prev m_prev
#define ifq_next m_next
#define ifs_prev m_prevpkt
#define ifs_next m_nextpkt
#define ifq_so m_so

#define M_EXT			0x01	/* m_ext points to more (malloced) data */
#define M_FREELIST		0x02	/* mbuf is on free list */
#define M_USEDLIST		0x04	/* XXX mbuf is on used list (for dtom()) */
#define M_DOFREE		0x08	/* when m_free is called on the mbuf, free()
					 * it rather than putting it on the free list */

void m_init(Slirp *);
struct mbuf * m_get(Slirp *);
void m_free(struct mbuf *);
void m_cat(register struct mbuf *, register struct mbuf *);
void m_inc(struct mbuf *, int);
void m_adj(struct mbuf *, int);
int m_copy(struct mbuf *, struct mbuf *, int, int);
struct mbuf * dtom(Slirp *, void *);

#endif