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/*
* 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>
int mbuf_alloced = 0;
struct mbuf m_freelist, m_usedlist;
#define MBUF_THRESH 30
int mbuf_max = 0;
/*
* Find a nice value for msize
* XXX if_maxlinkhdr already in mtu
*/
#define SLIRP_MSIZE (IF_MTU + IF_MAXLINKHDR + sizeof(struct m_hdr ) + 6)
void
m_init()
{
m_freelist.m_next = m_freelist.m_prev = &m_freelist;
m_usedlist.m_next = m_usedlist.m_prev = &m_usedlist;
}
/*
* 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(SLIRP_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 = SLIRP_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;
}
void
m_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
*/
void
m_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 */
void
m_inc(m, size)
struct mbuf *m;
int size;
{
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;
m->m_ext = (char *)realloc(m->m_ext,size);
/* if (m->m_ext == NULL)
* return (struct mbuf *)NULL;
*/
m->m_data = m->m_ext + datasize;
} else {
char *dat;
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_ext = dat;
m->m_data = m->m_ext + datasize;
m->m_flags |= M_EXT;
}
m->m_size = size;
}
void
m_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
*/
int
m_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;
}
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