2
* Copyright (c) 1995 Danny Gasparovski
4
* Please read the file COPYRIGHT for the
5
* terms and conditions of the copyright.
9
* mbuf's in SLiRP are much simpler than the real mbufs in
10
* FreeBSD. They are fixed size, determined by the MTU,
11
* so that one whole packet can fit. Mbuf's cannot be
12
* chained together. If there's more data than the mbuf
13
* could hold, an external malloced buffer is pointed to
14
* by m_ext (and the data pointers) and M_EXT is set in
24
struct mbuf m_freelist, m_usedlist;
32
m_freelist.m_next = m_freelist.m_prev = &m_freelist;
33
m_usedlist.m_next = m_usedlist.m_prev = &m_usedlist;
41
* Find a nice value for msize
42
* XXX if_maxlinkhdr already in mtu
44
msize = (if_mtu>if_mru?if_mtu:if_mru) +
45
if_maxlinkhdr + sizeof(struct m_hdr ) + 6;
49
* Get an mbuf from the free list, if there are none
52
* Because fragmentation can occur if we alloc new mbufs and
53
* free old mbufs, we mark all mbufs above mbuf_thresh as M_DOFREE,
54
* which tells m_free to actually free() it
59
register struct mbuf *m;
64
if (m_freelist.m_next == &m_freelist) {
65
m = (struct mbuf *)malloc(msize);
66
if (m == NULL) goto end_error;
68
if (mbuf_alloced > mbuf_thresh)
70
if (mbuf_alloced > mbuf_max)
71
mbuf_max = mbuf_alloced;
73
m = m_freelist.m_next;
77
/* Insert it in the used list */
78
insque(m,&m_usedlist);
79
m->m_flags = (flags | M_USEDLIST);
82
m->m_size = msize - sizeof(struct m_hdr);
88
DEBUG_ARG("m = %lx", (long )m);
98
DEBUG_ARG("m = %lx", (long )m);
101
/* Remove from m_usedlist */
102
if (m->m_flags & M_USEDLIST)
105
/* If it's M_EXT, free() it */
106
if (m->m_flags & M_EXT)
110
* Either free() it or put it on the free list
112
if (m->m_flags & M_DOFREE) {
115
} else if ((m->m_flags & M_FREELIST) == 0) {
116
insque(m,&m_freelist);
117
m->m_flags = M_FREELIST; /* Clobber other flags */
123
* Copy data from one mbuf to the end of
124
* the other.. if result is too big for one mbuf, malloc()
125
* an M_EXT data segment
129
register struct mbuf *m, *n;
132
* If there's no room, realloc
134
if (M_FREEROOM(m) < n->m_len)
135
m_inc(m,m->m_size+MINCSIZE);
137
memcpy(m->m_data+m->m_len, n->m_data, n->m_len);
138
m->m_len += n->m_len;
144
/* make m size bytes large */
152
/* some compiles throw up on gotos. This one we can fake. */
153
if(m->m_size>size) return;
155
if (m->m_flags & M_EXT) {
156
datasize = m->m_data - m->m_ext;
157
m->m_ext = (char *)realloc(m->m_ext,size);
158
/* if (m->m_ext == NULL)
159
* return (struct mbuf *)NULL;
161
m->m_data = m->m_ext + datasize;
164
datasize = m->m_data - m->m_dat;
165
dat = (char *)malloc(size);
167
* return (struct mbuf *)NULL;
169
memcpy(dat, m->m_dat, m->m_size);
172
m->m_data = m->m_ext + datasize;
202
* Copy len bytes from m, starting off bytes into n
205
m_copy(n, m, off, len)
209
if (len > M_FREEROOM(n))
212
memcpy((n->m_data + n->m_len), (m->m_data + off), len);
219
* Given a pointer into an mbuf, return the mbuf
220
* XXX This is a kludge, I should eliminate the need for it
221
* Fortunately, it's not used often
230
DEBUG_ARG("dat = %lx", (long )dat);
232
/* bug corrected for M_EXT buffers */
233
for (m = m_usedlist.m_next; m != &m_usedlist; m = m->m_next) {
234
if (m->m_flags & M_EXT) {
235
if( (char *)dat>=m->m_ext && (char *)dat<(m->m_ext + m->m_size) )
238
if( (char *)dat >= m->m_dat && (char *)dat<(m->m_dat + m->m_size) )
243
DEBUG_ERROR((dfd, "dtom failed"));
245
return (struct mbuf *)0;