1 /* SPDX-License-Identifier: BSD-3-Clause */
2 /*
3 * Copyright (c) 1982, 1986, 1988, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 *
30 * @(#)mbuf.h 8.3 (Berkeley) 1/21/94
31 * mbuf.h,v 1.9 1994/11/14 13:54:20 bde Exp
32 */
33
34 #ifndef MBUF_H
35 #define MBUF_H
36
37 /*
38 * Macros for type conversion
39 * mtod(m,t) - convert mbuf pointer to data pointer of correct type
40 */
41 #define mtod(m, t) ((t)(m)->m_data)
42
43 /* XXX About mbufs for slirp:
44 * Only one mbuf is ever used in a chain, for each "cell" of data.
45 * m_nextpkt points to the next packet, if fragmented.
46 * If the data is too large, the M_EXT is used, and a larger block
47 * is alloced. Therefore, m_free[m] must check for M_EXT and if set
48 * free the m_ext. This is inefficient memory-wise, but who cares.
49 */
50
51 /*
52 * mbufs allow to have a gap between the start of the allocated buffer (m_ext if
53 * M_EXT is set, m_dat otherwise) and the in-use data:
54 *
55 * |--gapsize----->|---m_len------->
56 * |----------m_size------------------------------>
57 * |----M_ROOM-------------------->
58 * |-M_FREEROOM-->
59 *
60 * ^ ^ ^
61 * m_dat/m_ext m_data end of buffer
62 */
63
64 /*
65 * How much room is in the mbuf, from m_data to the end of the mbuf
66 */
67 #define M_ROOM(m) \
68 ((m->m_flags & M_EXT) ? (((m)->m_ext + (m)->m_size) - (m)->m_data) : \
69 (((m)->m_dat + (m)->m_size) - (m)->m_data))
70
71 /*
72 * How much free room there is
73 */
74 #define M_FREEROOM(m) (M_ROOM(m) - (m)->m_len)
75
76 struct mbuf {
77 /* XXX should union some of these! */
78 /* header at beginning of each mbuf: */
79 struct mbuf *m_next; /* Linked list of mbufs */
80 struct mbuf *m_prev;
81 struct mbuf *m_nextpkt; /* Next packet in queue/record */
82 struct mbuf *m_prevpkt; /* Flags aren't used in the output queue */
83 int m_flags; /* Misc flags */
84
85 int m_size; /* Size of mbuf, from m_dat or m_ext */
86 struct socket *m_so;
87
88 char *m_data; /* Current location of data */
89 int m_len; /* Amount of data in this mbuf, from m_data */
90
91 Slirp *slirp;
92 bool resolution_requested;
93 uint64_t expiration_date;
94 char *m_ext;
95 /* start of dynamic buffer area, must be last element */
96 char m_dat[];
97 };
98
99 #define ifq_prev m_prev
100 #define ifq_next m_next
101 #define ifs_prev m_prevpkt
102 #define ifs_next m_nextpkt
103 #define ifq_so m_so
104
105 #define M_EXT 0x01 /* m_ext points to more (malloced) data */
106 #define M_FREELIST 0x02 /* mbuf is on free list */
107 #define M_USEDLIST 0x04 /* XXX mbuf is on used list (for dtom()) */
108 #define M_DOFREE \
109 0x08 /* when m_free is called on the mbuf, free() \
110 * it rather than putting it on the free list */
111
112 void m_init(Slirp *);
113 void m_cleanup(Slirp *slirp);
114 struct mbuf *m_get(Slirp *);
115 void m_free(struct mbuf *);
116 void m_cat(register struct mbuf *, register struct mbuf *);
117 void m_inc(struct mbuf *, int);
118 void m_adj(struct mbuf *, int);
119 int m_copy(struct mbuf *, struct mbuf *, int, int);
120 struct mbuf *dtom(Slirp *, void *);
121
ifs_init(struct mbuf * ifm)122 static inline void ifs_init(struct mbuf *ifm)
123 {
124 ifm->ifs_next = ifm->ifs_prev = ifm;
125 }
126
127 #endif
128