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/* SPDX-License-Identifier: BSD-3-Clause */
/*
* Copyright (c) 1982, 1986, 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)mbuf.h 8.3 (Berkeley) 1/21/94
* mbuf.h,v 1.9 1994/11/14 13:54:20 bde Exp
*/
#ifndef MBUF_H
#define MBUF_H
/*
* Macros for type conversion
* mtod(m,t) - convert mbuf pointer to data pointer of correct type
*/
#define mtod(m, t) ((t)(m)->m_data)
/* XXX About mbufs for slirp:
* Only one mbuf is ever used in a chain, for each "cell" of data.
* m_nextpkt points to the next packet, if fragmented.
* If the data is too large, the M_EXT is used, and a larger block
* is alloced. Therefore, m_free[m] must check for M_EXT and if set
* free the m_ext. This is inefficient memory-wise, but who cares.
*/
/*
* mbufs allow to have a gap between the start of the allocated buffer (m_ext if
* M_EXT is set, m_dat otherwise) and the in-use data:
*
* |--gapsize----->|---m_len------->
* |----------m_size------------------------------>
* |----M_ROOM-------------------->
* |-M_FREEROOM-->
*
* ^ ^ ^
* m_dat/m_ext m_data end of buffer
*/
/*
* How much room is in the mbuf, from m_data to the end of the mbuf
*/
#define M_ROOM(m) \
((m->m_flags & M_EXT) ? (((m)->m_ext + (m)->m_size) - (m)->m_data) : \
(((m)->m_dat + (m)->m_size) - (m)->m_data))
/*
* How much free room there is
*/
#define M_FREEROOM(m) (M_ROOM(m) - (m)->m_len)
/*
* How much free room there is before m_data
*/
#define M_ROOMBEFORE(m) \
(((m)->m_flags & M_EXT) ? (m)->m_data - (m)->m_ext \
: (m)->m_data - (m)->m_dat)
struct mbuf {
/* XXX should union some of these! */
/* header at beginning of each mbuf: */
struct mbuf *m_next; /* Linked list of mbufs */
struct mbuf *m_prev;
struct mbuf *m_nextpkt; /* Next packet in queue/record */
struct mbuf *m_prevpkt; /* Flags aren't used in the output queue */
int m_flags; /* Misc flags */
int m_size; /* Size of mbuf, from m_dat or m_ext */
struct socket *m_so;
char *m_data; /* Current location of data */
int m_len; /* Amount of data in this mbuf, from m_data */
Slirp *slirp;
bool resolution_requested;
uint64_t expiration_date;
char *m_ext;
/* start of dynamic buffer area, must be last element */
char m_dat[];
};
#define ifq_prev m_prev
#define ifq_next m_next
#define ifs_prev m_prevpkt
#define ifs_next m_nextpkt
#define ifq_so m_so
#define M_EXT 0x01 /* m_ext points to more (malloced) data */
#define M_FREELIST 0x02 /* mbuf is on free list */
#define M_USEDLIST 0x04 /* XXX mbuf is on used list (for dtom()) */
#define M_DOFREE \
0x08 /* when m_free is called on the mbuf, free() \
* it rather than putting it on the free list */
void m_init(Slirp *);
void m_cleanup(Slirp *slirp);
struct mbuf *m_get(Slirp *);
void m_free(struct mbuf *);
void m_cat(register struct mbuf *, register struct mbuf *);
void m_inc(struct mbuf *, int);
void m_adj(struct mbuf *, int);
int m_copy(struct mbuf *, struct mbuf *, int, int);
struct mbuf *m_dup(Slirp *slirp, struct mbuf *m, bool copy_header, size_t header_size);
struct mbuf *dtom(Slirp *, void *);
void *mtod_check(struct mbuf *, size_t len);
void *m_end(struct mbuf *);
static inline void ifs_init(struct mbuf *ifm)
{
ifm->ifs_next = ifm->ifs_prev = ifm;
}
#ifdef SLIRP_DEBUG
# define MBUF_DEBUG 1
#else
# ifdef HAVE_VALGRIND
# include <valgrind/valgrind.h>
# define MBUF_DEBUG RUNNING_ON_VALGRIND
# else
# define MBUF_DEBUG 0
# endif
#endif
/*
* When a function is given an mbuf as well as the responsibility to free it, we
* want valgrind etc. to properly identify the new responsible for the
* free. Achieve this by making a new copy. For instance:
*
* f0(void) {
* struct mbuf *m = m_get(slirp);
* [...]
* switch (something) {
* case 1:
* f1(m);
* break;
* case 2:
* f2(m);
* break;
* [...]
* }
* }
*
* f1(struct mbuf *m) {
* M_DUP_DEBUG(m->slirp, m);
* [...]
* m_free(m); // but author of f1 might be forgetting this
* }
*
* f0 transfers the freeing responsibility to f1, f2, etc. Without the
* M_DUP_DEBUG call in f1, valgrind would tell us that it is f0 where the buffer
* was allocated, but it's difficult to know whether a leak is actually in f0,
* or in f1, or in f2, etc. Duplicating the mbuf in M_DUP_DEBUG each time the
* responsibility is transferred allows to immediately know where the leak
* actually is.
*/
#define M_DUP_DEBUG(slirp, m, copy_header, header_size) do { \
if (MBUF_DEBUG) { \
struct mbuf *__n; \
__n = m_dup((slirp), (m), (copy_header), (header_size)); \
m_free(m); \
(m) = __n; \
} else { \
(void) (slirp); (void) (copy_header); \
g_assert(M_ROOMBEFORE(m) >= (header_size)); \
} \
} while(0)
#endif
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