root / slirp / mbuf.c @ 79383c9c
History | View | Annotate | Download (4.5 kB)
1 |
/*
|
---|---|
2 |
* Copyright (c) 1995 Danny Gasparovski
|
3 |
*
|
4 |
* Please read the file COPYRIGHT for the
|
5 |
* terms and conditions of the copyright.
|
6 |
*/
|
7 |
|
8 |
/*
|
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
|
15 |
* the flags
|
16 |
*/
|
17 |
|
18 |
#include <slirp.h> |
19 |
|
20 |
struct mbuf *mbutl;
|
21 |
char *mclrefcnt;
|
22 |
int mbuf_alloced = 0; |
23 |
struct mbuf m_freelist, m_usedlist;
|
24 |
#define MBUF_THRESH 30 |
25 |
int mbuf_max = 0; |
26 |
|
27 |
/*
|
28 |
* Find a nice value for msize
|
29 |
* XXX if_maxlinkhdr already in mtu
|
30 |
*/
|
31 |
#define SLIRP_MSIZE (IF_MTU + IF_MAXLINKHDR + sizeof(struct m_hdr ) + 6) |
32 |
|
33 |
void
|
34 |
m_init() |
35 |
{ |
36 |
m_freelist.m_next = m_freelist.m_prev = &m_freelist; |
37 |
m_usedlist.m_next = m_usedlist.m_prev = &m_usedlist; |
38 |
} |
39 |
|
40 |
/*
|
41 |
* Get an mbuf from the free list, if there are none
|
42 |
* malloc one
|
43 |
*
|
44 |
* Because fragmentation can occur if we alloc new mbufs and
|
45 |
* free old mbufs, we mark all mbufs above mbuf_thresh as M_DOFREE,
|
46 |
* which tells m_free to actually free() it
|
47 |
*/
|
48 |
struct mbuf *
|
49 |
m_get() |
50 |
{ |
51 |
register struct mbuf *m; |
52 |
int flags = 0; |
53 |
|
54 |
DEBUG_CALL("m_get");
|
55 |
|
56 |
if (m_freelist.m_next == &m_freelist) {
|
57 |
m = (struct mbuf *)malloc(SLIRP_MSIZE);
|
58 |
if (m == NULL) goto end_error; |
59 |
mbuf_alloced++; |
60 |
if (mbuf_alloced > MBUF_THRESH)
|
61 |
flags = M_DOFREE; |
62 |
if (mbuf_alloced > mbuf_max)
|
63 |
mbuf_max = mbuf_alloced; |
64 |
} else {
|
65 |
m = m_freelist.m_next; |
66 |
remque(m); |
67 |
} |
68 |
|
69 |
/* Insert it in the used list */
|
70 |
insque(m,&m_usedlist); |
71 |
m->m_flags = (flags | M_USEDLIST); |
72 |
|
73 |
/* Initialise it */
|
74 |
m->m_size = SLIRP_MSIZE - sizeof(struct m_hdr); |
75 |
m->m_data = m->m_dat; |
76 |
m->m_len = 0;
|
77 |
m->m_nextpkt = 0;
|
78 |
m->m_prevpkt = 0;
|
79 |
end_error:
|
80 |
DEBUG_ARG("m = %lx", (long )m); |
81 |
return m;
|
82 |
} |
83 |
|
84 |
void
|
85 |
m_free(m) |
86 |
struct mbuf *m;
|
87 |
{ |
88 |
|
89 |
DEBUG_CALL("m_free");
|
90 |
DEBUG_ARG("m = %lx", (long )m); |
91 |
|
92 |
if(m) {
|
93 |
/* Remove from m_usedlist */
|
94 |
if (m->m_flags & M_USEDLIST)
|
95 |
remque(m); |
96 |
|
97 |
/* If it's M_EXT, free() it */
|
98 |
if (m->m_flags & M_EXT)
|
99 |
free(m->m_ext); |
100 |
|
101 |
/*
|
102 |
* Either free() it or put it on the free list
|
103 |
*/
|
104 |
if (m->m_flags & M_DOFREE) {
|
105 |
free(m); |
106 |
mbuf_alloced--; |
107 |
} else if ((m->m_flags & M_FREELIST) == 0) { |
108 |
insque(m,&m_freelist); |
109 |
m->m_flags = M_FREELIST; /* Clobber other flags */
|
110 |
} |
111 |
} /* if(m) */
|
112 |
} |
113 |
|
114 |
/*
|
115 |
* Copy data from one mbuf to the end of
|
116 |
* the other.. if result is too big for one mbuf, malloc()
|
117 |
* an M_EXT data segment
|
118 |
*/
|
119 |
void
|
120 |
m_cat(m, n) |
121 |
register struct mbuf *m, *n; |
122 |
{ |
123 |
/*
|
124 |
* If there's no room, realloc
|
125 |
*/
|
126 |
if (M_FREEROOM(m) < n->m_len)
|
127 |
m_inc(m,m->m_size+MINCSIZE); |
128 |
|
129 |
memcpy(m->m_data+m->m_len, n->m_data, n->m_len); |
130 |
m->m_len += n->m_len; |
131 |
|
132 |
m_free(n); |
133 |
} |
134 |
|
135 |
|
136 |
/* make m size bytes large */
|
137 |
void
|
138 |
m_inc(m, size) |
139 |
struct mbuf *m;
|
140 |
int size;
|
141 |
{ |
142 |
int datasize;
|
143 |
|
144 |
/* some compiles throw up on gotos. This one we can fake. */
|
145 |
if(m->m_size>size) return; |
146 |
|
147 |
if (m->m_flags & M_EXT) {
|
148 |
datasize = m->m_data - m->m_ext; |
149 |
m->m_ext = (char *)realloc(m->m_ext,size);
|
150 |
/* if (m->m_ext == NULL)
|
151 |
* return (struct mbuf *)NULL;
|
152 |
*/
|
153 |
m->m_data = m->m_ext + datasize; |
154 |
} else {
|
155 |
char *dat;
|
156 |
datasize = m->m_data - m->m_dat; |
157 |
dat = (char *)malloc(size);
|
158 |
/* if (dat == NULL)
|
159 |
* return (struct mbuf *)NULL;
|
160 |
*/
|
161 |
memcpy(dat, m->m_dat, m->m_size); |
162 |
|
163 |
m->m_ext = dat; |
164 |
m->m_data = m->m_ext + datasize; |
165 |
m->m_flags |= M_EXT; |
166 |
} |
167 |
|
168 |
m->m_size = size; |
169 |
|
170 |
} |
171 |
|
172 |
|
173 |
|
174 |
void
|
175 |
m_adj(m, len) |
176 |
struct mbuf *m;
|
177 |
int len;
|
178 |
{ |
179 |
if (m == NULL) |
180 |
return;
|
181 |
if (len >= 0) { |
182 |
/* Trim from head */
|
183 |
m->m_data += len; |
184 |
m->m_len -= len; |
185 |
} else {
|
186 |
/* Trim from tail */
|
187 |
len = -len; |
188 |
m->m_len -= len; |
189 |
} |
190 |
} |
191 |
|
192 |
|
193 |
/*
|
194 |
* Copy len bytes from m, starting off bytes into n
|
195 |
*/
|
196 |
int
|
197 |
m_copy(n, m, off, len) |
198 |
struct mbuf *n, *m;
|
199 |
int off, len;
|
200 |
{ |
201 |
if (len > M_FREEROOM(n))
|
202 |
return -1; |
203 |
|
204 |
memcpy((n->m_data + n->m_len), (m->m_data + off), len); |
205 |
n->m_len += len; |
206 |
return 0; |
207 |
} |
208 |
|
209 |
|
210 |
/*
|
211 |
* Given a pointer into an mbuf, return the mbuf
|
212 |
* XXX This is a kludge, I should eliminate the need for it
|
213 |
* Fortunately, it's not used often
|
214 |
*/
|
215 |
struct mbuf *
|
216 |
dtom(dat) |
217 |
void *dat;
|
218 |
{ |
219 |
struct mbuf *m;
|
220 |
|
221 |
DEBUG_CALL("dtom");
|
222 |
DEBUG_ARG("dat = %lx", (long )dat); |
223 |
|
224 |
/* bug corrected for M_EXT buffers */
|
225 |
for (m = m_usedlist.m_next; m != &m_usedlist; m = m->m_next) {
|
226 |
if (m->m_flags & M_EXT) {
|
227 |
if( (char *)dat>=m->m_ext && (char *)dat<(m->m_ext + m->m_size) ) |
228 |
return m;
|
229 |
} else {
|
230 |
if( (char *)dat >= m->m_dat && (char *)dat<(m->m_dat + m->m_size) ) |
231 |
return m;
|
232 |
} |
233 |
} |
234 |
|
235 |
DEBUG_ERROR((dfd, "dtom failed"));
|
236 |
|
237 |
return (struct mbuf *)0; |
238 |
} |
239 |
|