/* 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 # 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