/* * Copyright (c) 1995 Danny Gasparovski * * Please read the file COPYRIGHT for the * terms and conditions of the copyright. *//* * mbuf's in SLiRP are much simpler than the real mbufs in * FreeBSD.  They are fixed size, determined by the MTU, * so that one whole packet can fit.  Mbuf's cannot be * chained together.  If there's more data than the mbuf * could hold, an external malloced buffer is pointed to * by m_ext (and the data pointers) and M_EXT is set in * the flags */#include "slirp.h"struct	mbuf *mbutl;char	*mclrefcnt;int mbuf_alloced = 0;struct mbuf m_freelist, m_usedlist;int mbuf_thresh = 30;int mbuf_max = 0;int msize;voidm_init(){	m_freelist.m_next = m_freelist.m_prev = &m_freelist;	m_usedlist.m_next = m_usedlist.m_prev = &m_usedlist;	msize_init();}voidmsize_init(){	/*	 * Find a nice value for msize	 * XXX if_maxlinkhdr already in mtu	 */	msize = (if_mtu>if_mru?if_mtu:if_mru) + 			if_maxlinkhdr + sizeof(struct m_hdr ) + 6;}/* * Get an mbuf from the free list, if there are none * malloc one *  * Because fragmentation can occur if we alloc new mbufs and * free old mbufs, we mark all mbufs above mbuf_thresh as M_DOFREE, * which tells m_free to actually free() it */struct mbuf *m_get(){	register struct mbuf *m;	int flags = 0;		DEBUG_CALL("m_get");		if (m_freelist.m_next == &m_freelist) {		m = (struct mbuf *)malloc(msize);		if (m == NULL) goto end_error;		mbuf_alloced++;		if (mbuf_alloced > mbuf_thresh)			flags = M_DOFREE;		if (mbuf_alloced > mbuf_max)			mbuf_max = mbuf_alloced;	} else {		m = m_freelist.m_next;		remque(m);	}		/* Insert it in the used list */	insque(m,&m_usedlist);	m->m_flags = (flags | M_USEDLIST);		/* Initialise it */	m->m_size = msize - sizeof(struct m_hdr);	m->m_data = m->m_dat;	m->m_len = 0;	m->m_nextpkt = 0;	m->m_prevpkt = 0;end_error:	DEBUG_ARG("m = %lx", (long )m);	return m;}voidm_free(m)	struct mbuf *m;{	  DEBUG_CALL("m_free");  DEBUG_ARG("m = %lx", (long )m);	  if(m) {	/* Remove from m_usedlist */	if (m->m_flags & M_USEDLIST)	   remque(m);		/* If it's M_EXT, free() it */	if (m->m_flags & M_EXT)	   free(m->m_ext);	/*	 * Either free() it or put it on the free list	 */	if (m->m_flags & M_DOFREE) {		free(m);		mbuf_alloced--;	} else if ((m->m_flags & M_FREELIST) == 0) {		insque(m,&m_freelist);		m->m_flags = M_FREELIST; /* Clobber other flags */	}  } /* if(m) */}/* * Copy data from one mbuf to the end of * the other.. if result is too big for one mbuf, malloc() * an M_EXT data segment */voidm_cat(m, n)	register struct mbuf *m, *n;{	/*	 * If there's no room, realloc	 */	if (M_FREEROOM(m) < n->m_len)		m_inc(m,m->m_size+MINCSIZE);		memcpy(m->m_data+m->m_len, n->m_data, n->m_len);	m->m_len += n->m_len;	m_free(n);}/* make m size bytes large */voidm_inc(m, size)        struct mbuf *m;        int size;{	char *dat;	int datasize;	/* some compiles throw up on gotos.  This one we can fake. */        if(m->m_size>size) return;        if (m->m_flags & M_EXT) {	  datasize = m->m_data - m->m_ext;	  dat = (char *)realloc(m->m_ext,size);/*		if (dat == NULL) *			return (struct mbuf *)NULL; */		        } else {	  datasize = m->m_data - m->m_dat;	  dat = (char *)malloc(size);/*		if (dat == NULL) *			return (struct mbuf *)NULL; */	  memcpy(dat, m->m_dat, m->m_size);	  	  m->m_flags |= M_EXT;        } 	m->m_ext = dat;	m->m_data = m->m_ext + datasize;        m->m_size = size;}voidm_adj(m, len)	struct mbuf *m;	int len;{	if (m == NULL)		return;	if (len >= 0) {		/* Trim from head */		m->m_data += len;		m->m_len -= len;	} else {		/* Trim from tail */		len = -len;		m->m_len -= len;	}}/* * Copy len bytes from m, starting off bytes into n */intm_copy(n, m, off, len)	struct mbuf *n, *m;	int off, len;{	if (len > M_FREEROOM(n))		return -1;	memcpy((n->m_data + n->m_len), (m->m_data + off), len);	n->m_len += len;	return 0;}/* * Given a pointer into an mbuf, return the mbuf * XXX This is a kludge, I should eliminate the need for it * Fortunately, it's not used often */struct mbuf *dtom(dat)	void *dat;{	struct mbuf *m;		DEBUG_CALL("dtom");	DEBUG_ARG("dat = %lx", (long )dat);	/* bug corrected for M_EXT buffers */	for (m = m_usedlist.m_next; m != &m_usedlist; m = m->m_next) {	  if (m->m_flags & M_EXT) {	    if( (char *)dat>=m->m_ext && (char *)dat<(m->m_ext + m->m_size) )	      return m;	  } else {	    if( (char *)dat >= m->m_dat && (char *)dat<(m->m_dat + m->m_size) )	      return m;	  }	}		DEBUG_ERROR((dfd, "dtom failed"));		return (struct mbuf *)0;}