888de86e45c4e222c52e70a86f85937dde9f87d6
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
20 static int mbuf_alloced
;
21 struct mbuf m_freelist
, m_usedlist
;
22 #define MBUF_THRESH 30
25 * Find a nice value for msize
26 * XXX if_maxlinkhdr already in mtu
28 #define SLIRP_MSIZE (IF_MTU + IF_MAXLINKHDR + sizeof(struct m_hdr ) + 6)
33 m_freelist
.m_next
= m_freelist
.m_prev
= &m_freelist
;
34 m_usedlist
.m_next
= m_usedlist
.m_prev
= &m_usedlist
;
38 * Get an mbuf from the free list, if there are none
41 * Because fragmentation can occur if we alloc new mbufs and
42 * free old mbufs, we mark all mbufs above mbuf_thresh as M_DOFREE,
43 * which tells m_free to actually free() it
48 register struct mbuf
*m
;
53 if (m_freelist
.m_next
== &m_freelist
) {
54 m
= (struct mbuf
*)malloc(SLIRP_MSIZE
);
55 if (m
== NULL
) goto end_error
;
57 if (mbuf_alloced
> MBUF_THRESH
)
60 m
= m_freelist
.m_next
;
64 /* Insert it in the used list */
65 insque(m
,&m_usedlist
);
66 m
->m_flags
= (flags
| M_USEDLIST
);
69 m
->m_size
= SLIRP_MSIZE
- sizeof(struct m_hdr
);
75 DEBUG_ARG("m = %lx", (long )m
);
80 m_free(struct mbuf
*m
)
84 DEBUG_ARG("m = %lx", (long )m
);
87 /* Remove from m_usedlist */
88 if (m
->m_flags
& M_USEDLIST
)
91 /* If it's M_EXT, free() it */
92 if (m
->m_flags
& M_EXT
)
96 * Either free() it or put it on the free list
98 if (m
->m_flags
& M_DOFREE
) {
101 } else if ((m
->m_flags
& M_FREELIST
) == 0) {
102 insque(m
,&m_freelist
);
103 m
->m_flags
= M_FREELIST
; /* Clobber other flags */
109 * Copy data from one mbuf to the end of
110 * the other.. if result is too big for one mbuf, malloc()
111 * an M_EXT data segment
114 m_cat(struct mbuf
*m
, struct mbuf
*n
)
117 * If there's no room, realloc
119 if (M_FREEROOM(m
) < n
->m_len
)
120 m_inc(m
,m
->m_size
+MINCSIZE
);
122 memcpy(m
->m_data
+m
->m_len
, n
->m_data
, n
->m_len
);
123 m
->m_len
+= n
->m_len
;
129 /* make m size bytes large */
131 m_inc(struct mbuf
*m
, int size
)
135 /* some compiles throw up on gotos. This one we can fake. */
136 if(m
->m_size
>size
) return;
138 if (m
->m_flags
& M_EXT
) {
139 datasize
= m
->m_data
- m
->m_ext
;
140 m
->m_ext
= (char *)realloc(m
->m_ext
,size
);
141 m
->m_data
= m
->m_ext
+ datasize
;
144 datasize
= m
->m_data
- m
->m_dat
;
145 dat
= (char *)malloc(size
);
146 memcpy(dat
, m
->m_dat
, m
->m_size
);
149 m
->m_data
= m
->m_ext
+ datasize
;
160 m_adj(struct mbuf
*m
, int len
)
177 * Copy len bytes from m, starting off bytes into n
180 m_copy(struct mbuf
*n
, struct mbuf
*m
, int off
, int len
)
182 if (len
> M_FREEROOM(n
))
185 memcpy((n
->m_data
+ n
->m_len
), (m
->m_data
+ off
), len
);
192 * Given a pointer into an mbuf, return the mbuf
193 * XXX This is a kludge, I should eliminate the need for it
194 * Fortunately, it's not used often
202 DEBUG_ARG("dat = %lx", (long )dat
);
204 /* bug corrected for M_EXT buffers */
205 for (m
= m_usedlist
.m_next
; m
!= &m_usedlist
; m
= m
->m_next
) {
206 if (m
->m_flags
& M_EXT
) {
207 if( (char *)dat
>=m
->m_ext
&& (char *)dat
<(m
->m_ext
+ m
->m_size
) )
210 if( (char *)dat
>= m
->m_dat
&& (char *)dat
<(m
->m_dat
+ m
->m_size
) )
215 DEBUG_ERROR((dfd
, "dtom failed"));
217 return (struct mbuf
*)0;