/*      $NetBSD: mbuf.h,v 1.240 2024/05/12 10:34:56 rillig Exp $        */

/*
 * Copyright (c) 1996, 1997, 1999, 2001, 2007 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
 * NASA Ames Research Center and Matt Thomas of 3am Software Foundry.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * 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      8.5 (Berkeley) 2/19/95
 */

#ifndef _SYS_MBUF_H_
#define _SYS_MBUF_H_

#ifdef _KERNEL_OPT
#include "opt_mbuftrace.h"
#endif

#ifndef M_WAITOK
#include <sys/malloc.h>
#endif
#include <sys/pool.h>
#include <sys/queue.h>
#if defined(_KERNEL)
#include <sys/percpu_types.h>
#include <sys/socket.h> /* for AF_UNSPEC */
#include <sys/psref.h>
#endif /* defined(_KERNEL) */

/* For offsetof() */
#if defined(_KERNEL) || defined(_STANDALONE)
#include <sys/systm.h>
#else
#include <stddef.h>
#endif

#include <uvm/uvm_param.h>      /* for MIN_PAGE_SIZE */

#include <net/if.h>

/*
 * Mbufs are of a single size, MSIZE (machine/param.h), which
 * includes overhead.  An mbuf may add a single "mbuf cluster" of size
 * MCLBYTES (also in machine/param.h), which has no additional overhead
 * and is used instead of the internal data area; this is done when
 * at least MINCLSIZE of data must be stored.
 */

/* Packet tags structure */
struct m_tag {
        SLIST_ENTRY(m_tag)      m_tag_link;     /* List of packet tags */
        uint16_t                m_tag_id;       /* Tag ID */
        uint16_t                m_tag_len;      /* Length of data */
};

/* mbuf ownership structure */
struct mowner {
        char mo_name[16];               /* owner name (fxp0) */
        char mo_descr[16];              /* owner description (input) */
        LIST_ENTRY(mowner) mo_link;     /* */
        struct percpu *mo_counters;
};

#define MOWNER_INIT(x, y) { .mo_name = x, .mo_descr = y }

enum mowner_counter_index {
        MOWNER_COUNTER_CLAIMS,          /* # of small mbuf claimed */
        MOWNER_COUNTER_RELEASES,        /* # of small mbuf released */
        MOWNER_COUNTER_CLUSTER_CLAIMS,  /* # of cluster mbuf claimed */
        MOWNER_COUNTER_CLUSTER_RELEASES,/* # of cluster mbuf released */
        MOWNER_COUNTER_EXT_CLAIMS,      /* # of M_EXT mbuf claimed */
        MOWNER_COUNTER_EXT_RELEASES,    /* # of M_EXT mbuf released */

        MOWNER_COUNTER_NCOUNTERS,
};

#if defined(_KERNEL)
struct mowner_counter {
        u_long mc_counter[MOWNER_COUNTER_NCOUNTERS];
};
#endif

/* userland-exported version of struct mowner */
struct mowner_user {
        char mo_name[16];               /* owner name (fxp0) */
        char mo_descr[16];              /* owner description (input) */
        LIST_ENTRY(mowner) mo_link;     /* unused padding; for compatibility */
        u_long mo_counter[MOWNER_COUNTER_NCOUNTERS]; /* counters */
};

/*
 * Macros for type conversion
 * mtod(m,t) -  convert mbuf pointer to data pointer of correct type
 */
#define mtod(m, t)      ((t)((m)->m_data))

/* header at beginning of each mbuf */
struct m_hdr {
        struct  mbuf *mh_next;          /* next buffer in chain */
        struct  mbuf *mh_nextpkt;       /* next chain in queue/record */
        char    *mh_data;               /* location of data */
        struct  mowner *mh_owner;       /* mbuf owner */
        int     mh_len;                 /* amount of data in this mbuf */
        int     mh_flags;               /* flags; see below */
        paddr_t mh_paddr;               /* physical address of mbuf */
        short   mh_type;                /* type of data in this mbuf */
};

/*
 * record/packet header in first mbuf of chain; valid if M_PKTHDR set
 *
 * A note about csum_data:
 *
 *  o For the out-bound direction, the low 16 bits indicates the offset after
 *    the L4 header where the final L4 checksum value is to be stored and the
 *    high 16 bits is the length of the L3 header (the start of the data to
 *    be checksummed).
 *
 *  o For the in-bound direction, it is only valid if the M_CSUM_DATA flag is
 *    set. In this case, an L4 checksum has been calculated by hardware and
 *    is stored in csum_data, but it is up to software to perform final
 *    verification.
 *
 * Note for in-bound TCP/UDP checksums: we expect the csum_data to NOT
 * be bit-wise inverted (the final step in the calculation of an IP
 * checksum) -- this is so we can accumulate the checksum for fragmented
 * packets during reassembly.
 *
 * Size ILP32: 40
 *       LP64: 56
 */
struct pkthdr {
        union {
                void            *ctx;           /* for M_GETCTX/M_SETCTX */
                if_index_t      index;          /* rcv interface index */
        } _rcvif;
#define rcvif_index             _rcvif.index
        SLIST_HEAD(packet_tags, m_tag) tags;    /* list of packet tags */
        int             len;                    /* total packet length */
        int             csum_flags;             /* checksum flags */
        uint32_t        csum_data;              /* checksum data */
        u_int           segsz;                  /* segment size */
        uint16_t        ether_vtag;             /* ethernet 802.1p+q vlan tag */
        uint16_t        pkthdr_flags;           /* flags for pkthdr, see blow */
#define PKTHDR_FLAG_IPSEC_SKIP_PFIL     0x0001  /* skip pfil_run_hooks() after ipsec decrypt */

        /*
         * Following three fields are open-coded struct altq_pktattr
         * to rearrange struct pkthdr fields flexibly.
         */
        int     pattr_af;               /* ALTQ: address family */
        void    *pattr_class;           /* ALTQ: sched class set by classifier */
        void    *pattr_hdr;             /* ALTQ: saved header position in mbuf */
};

/* Checksumming flags (csum_flags). */
#define M_CSUM_TCPv4            0x00000001      /* TCP header/payload */
#define M_CSUM_UDPv4            0x00000002      /* UDP header/payload */
#define M_CSUM_TCP_UDP_BAD      0x00000004      /* TCP/UDP checksum bad */
#define M_CSUM_DATA             0x00000008      /* consult csum_data */
#define M_CSUM_TCPv6            0x00000010      /* IPv6 TCP header/payload */
#define M_CSUM_UDPv6            0x00000020      /* IPv6 UDP header/payload */
#define M_CSUM_IPv4             0x00000040      /* IPv4 header */
#define M_CSUM_IPv4_BAD         0x00000080      /* IPv4 header checksum bad */
#define M_CSUM_TSOv4            0x00000100      /* TCPv4 segmentation offload */
#define M_CSUM_TSOv6            0x00000200      /* TCPv6 segmentation offload */

/* Checksum-assist quirks: keep separate from jump-table bits. */
#define M_CSUM_BLANK            0x40000000      /* csum is missing */
#define M_CSUM_NO_PSEUDOHDR     0x80000000      /* Rx csum_data does not include
                                                 * the UDP/TCP pseudo-hdr, and
                                                 * is not yet 1s-complemented.
                                                 */

#define M_CSUM_BITS \
    "\20\1TCPv4\2UDPv4\3TCP_UDP_BAD\4DATA\5TCPv6\6UDPv6\7IPv4\10IPv4_BAD" \
    "\11TSOv4\12TSOv6\37BLANK\40NO_PSEUDOHDR"

/*
 * Macros for manipulating csum_data on outgoing packets. These are
 * used to pass information down from the L4/L3 to the L2.
 *
 *   _IPHL:   Length of the IPv{4/6} header, plus the options; in other
 *            words the offset of the UDP/TCP header in the packet.
 *   _OFFSET: Offset of the checksum field in the UDP/TCP header.
 */
#define M_CSUM_DATA_IPv4_IPHL(x)        ((x) >> 16)
#define M_CSUM_DATA_IPv4_OFFSET(x)      ((x) & 0xffff)
#define M_CSUM_DATA_IPv6_IPHL(x)        ((x) >> 16)
#define M_CSUM_DATA_IPv6_OFFSET(x)      ((x) & 0xffff)
#define M_CSUM_DATA_IPv6_SET(x, v)      (x) = ((x) & 0xffff) | ((v) << 16)

/*
 * Max # of pages we can attach to m_ext.  This is carefully chosen
 * to be able to handle SOSEND_LOAN_CHUNK with our minimum sized page.
 */
#ifdef MIN_PAGE_SIZE
#define M_EXT_MAXPAGES          ((65536 / MIN_PAGE_SIZE) + 1)
#endif

/*
 * Description of external storage mapped into mbuf, valid if M_EXT set.
 */
struct _m_ext_storage {
        unsigned int ext_refcnt;
        char *ext_buf;                  /* start of buffer */
        void (*ext_free)                /* free routine if not the usual */
                (struct mbuf *, void *, size_t, void *);
        void *ext_arg;                  /* argument for ext_free */
        size_t ext_size;                /* size of buffer, for ext_free */

        union {
                /* M_EXT_CLUSTER: physical address */
                paddr_t extun_paddr;
#ifdef M_EXT_MAXPAGES
                /* M_EXT_PAGES: pages */
                struct vm_page *extun_pgs[M_EXT_MAXPAGES];
#endif
        } ext_un;
#define ext_paddr       ext_un.extun_paddr
#define ext_pgs         ext_un.extun_pgs
};

struct _m_ext {
        struct mbuf *ext_ref;
        struct _m_ext_storage ext_storage;
};

#define M_PADDR_INVALID         POOL_PADDR_INVALID

/*
 * Definition of "struct mbuf".
 * Don't change this without understanding how MHLEN/MLEN are defined.
 */
#define MBUF_DEFINE(name, mhlen, mlen)                                  \
        struct name {                                                   \
                struct m_hdr m_hdr;                                     \
                union {                                                 \
                        struct {                                        \
                                struct pkthdr MH_pkthdr;                \
                                union {                                 \
                                        struct _m_ext MH_ext;           \
                                        char MH_databuf[(mhlen)];       \
                                } MH_dat;                               \
                        } MH;                                           \
                        char M_databuf[(mlen)];                         \
                } M_dat;                                                \
        }
#define m_next          m_hdr.mh_next
#define m_len           m_hdr.mh_len
#define m_data          m_hdr.mh_data
#define m_owner         m_hdr.mh_owner
#define m_type          m_hdr.mh_type
#define m_flags         m_hdr.mh_flags
#define m_nextpkt       m_hdr.mh_nextpkt
#define m_paddr         m_hdr.mh_paddr
#define m_pkthdr        M_dat.MH.MH_pkthdr
#define m_ext_storage   M_dat.MH.MH_dat.MH_ext.ext_storage
#define m_ext_ref       M_dat.MH.MH_dat.MH_ext.ext_ref
#define m_ext           m_ext_ref->m_ext_storage
#define m_pktdat        M_dat.MH.MH_dat.MH_databuf
#define m_dat           M_dat.M_databuf

/*
 * Dummy mbuf structure to calculate the right values for MLEN/MHLEN, taking
 * into account inter-structure padding.
 */
MBUF_DEFINE(_mbuf_dummy, 1, 1);

/* normal data len */
#define MLEN            ((int)(MSIZE - offsetof(struct _mbuf_dummy, m_dat)))
/* data len w/pkthdr */
#define MHLEN           ((int)(MSIZE - offsetof(struct _mbuf_dummy, m_pktdat)))

#define MINCLSIZE       (MHLEN+MLEN+1)  /* smallest amount to put in cluster */

/*
 * The *real* struct mbuf
 */
MBUF_DEFINE(mbuf, MHLEN, MLEN);

/* mbuf flags */
#define M_EXT           0x00000001      /* has associated external storage */
#define M_PKTHDR        0x00000002      /* start of record */
#define M_EOR           0x00000004      /* end of record */
#define M_PROTO1        0x00000008      /* protocol-specific */

/* mbuf pkthdr flags, also in m_flags */
#define M_AUTHIPHDR     0x00000010      /* authenticated (IPsec) */
#define M_DECRYPTED     0x00000020      /* decrypted (IPsec) */
#define M_LOOP          0x00000040      /* received on loopback */
#define M_BCAST         0x00000100      /* send/received as L2 broadcast */
#define M_MCAST         0x00000200      /* send/received as L2 multicast */
#define M_CANFASTFWD    0x00000400      /* packet can be fast-forwarded */
#define M_ANYCAST6      0x00000800      /* received as IPv6 anycast */

#define M_LINK0         0x00001000      /* link layer specific flag */
#define M_LINK1         0x00002000      /* link layer specific flag */
#define M_LINK2         0x00004000      /* link layer specific flag */
#define M_LINK3         0x00008000      /* link layer specific flag */
#define M_LINK4         0x00010000      /* link layer specific flag */
#define M_LINK5         0x00020000      /* link layer specific flag */
#define M_LINK6         0x00040000      /* link layer specific flag */
#define M_LINK7         0x00080000      /* link layer specific flag */

#define M_VLANTAG       0x00100000      /* ether_vtag is valid */

/* additional flags for M_EXT mbufs */
#define M_EXT_FLAGS     0xff000000
#define M_EXT_CLUSTER   0x01000000      /* ext is a cluster */
#define M_EXT_PAGES     0x02000000      /* ext_pgs is valid */
#define M_EXT_ROMAP     0x04000000      /* ext mapping is r-o at MMU */
#define M_EXT_RW        0x08000000      /* ext storage is writable */

/* for source-level compatibility */
#define M_NOTIFICATION  M_PROTO1

#define M_FLAGS_BITS \
    "\20\1EXT\2PKTHDR\3EOR\4PROTO1\5AUTHIPHDR\6DECRYPTED\7LOOP\10NONE" \
    "\11BCAST\12MCAST\13CANFASTFWD\14ANYCAST6\15LINK0\16LINK1\17LINK2\20LINK3" \
    "\21LINK4\22LINK5\23LINK6\24LINK7" \
    "\25VLANTAG" \
    "\31EXT_CLUSTER\32EXT_PAGES\33EXT_ROMAP\34EXT_RW"

/* flags copied when copying m_pkthdr */
#define M_COPYFLAGS     (M_PKTHDR|M_EOR|M_BCAST|M_MCAST|M_CANFASTFWD| \
    M_ANYCAST6|M_LINK0|M_LINK1|M_LINK2|M_AUTHIPHDR|M_DECRYPTED|M_LOOP| \
    M_VLANTAG)

/* flag copied when shallow-copying external storage */
#define M_EXTCOPYFLAGS  (M_EXT|M_EXT_FLAGS)

/* mbuf types */
#define MT_FREE         0       /* should be on free list */
#define MT_DATA         1       /* dynamic (data) allocation */
#define MT_HEADER       2       /* packet header */
#define MT_SONAME       3       /* socket name */
#define MT_SOOPTS       4       /* socket options */
#define MT_FTABLE       5       /* fragment reassembly header */
#define MT_CONTROL      6       /* extra-data protocol message */
#define MT_OOBDATA      7       /* expedited data  */

#ifdef MBUFTYPES
const char * const mbuftypes[] = {
        "mbfree",
        "mbdata",
        "mbheader",
        "mbsoname",
        "mbsopts",
        "mbftable",
        "mbcontrol",
        "mboobdata",
};
#else
extern const char * const mbuftypes[];
#endif

/* flags to m_get/MGET */
#define M_DONTWAIT      M_NOWAIT
#define M_WAIT          M_WAITOK

#ifdef MBUFTRACE
/* Mbuf allocation tracing. */
void mowner_init_owner(struct mowner *, const char *, const char *);
void mowner_init(struct mbuf *, int);
void mowner_ref(struct mbuf *, int);
void m_claim(struct mbuf *, struct mowner *);
void mowner_revoke(struct mbuf *, bool, int);
void mowner_attach(struct mowner *);
void mowner_detach(struct mowner *);
void m_claimm(struct mbuf *, struct mowner *);
#else
#define mowner_init_owner(mo, n, d)     __nothing
#define mowner_init(m, type)            __nothing
#define mowner_ref(m, flags)            __nothing
#define mowner_revoke(m, all, flags)    __nothing
#define m_claim(m, mowner)              __nothing
#define mowner_attach(mo)               __nothing
#define mowner_detach(mo)               __nothing
#define m_claimm(m, mo)                 __nothing
#endif

#define MCLAIM(m, mo)           m_claim((m), (mo))
#define MOWNER_ATTACH(mo)       mowner_attach(mo)
#define MOWNER_DETACH(mo)       mowner_detach(mo)

/*
 * mbuf allocation/deallocation macros:
 *
 *      MGET(struct mbuf *m, int how, int type)
 * allocates an mbuf and initializes it to contain internal data.
 *
 *      MGETHDR(struct mbuf *m, int how, int type)
 * allocates an mbuf and initializes it to contain a packet header
 * and internal data.
 *
 * If 'how' is M_WAIT, these macros (and the corresponding functions)
 * are guaranteed to return successfully.
 */
#define MGET(m, how, type)      m = m_get((how), (type))
#define MGETHDR(m, how, type)   m = m_gethdr((how), (type))

#if defined(_KERNEL)

#define MCLINITREFERENCE(m)                                             \
do {                                                                    \
        KASSERT(((m)->m_flags & M_EXT) == 0);                           \
        (m)->m_ext_ref = (m);                                           \
        (m)->m_ext.ext_refcnt = 1;                                      \
} while (0)

/*
 * Macros for mbuf external storage.
 *
 * MCLGET allocates and adds an mbuf cluster to a normal mbuf;
 * the flag M_EXT is set upon success.
 *
 * MEXTMALLOC allocates external storage and adds it to
 * a normal mbuf; the flag M_EXT is set upon success.
 *
 * MEXTADD adds pre-allocated external storage to
 * a normal mbuf; the flag M_EXT is set upon success.
 */

#define MCLGET(m, how)  m_clget((m), (how))

#define MEXTMALLOC(m, size, how)                                        \
do {                                                                    \
        (m)->m_ext_storage.ext_buf = malloc((size), 0, (how));          \
        if ((m)->m_ext_storage.ext_buf != NULL) {                       \
                MCLINITREFERENCE(m);                                    \
                (m)->m_data = (m)->m_ext.ext_buf;                       \
                (m)->m_flags = ((m)->m_flags & ~M_EXTCOPYFLAGS) |       \
                                M_EXT|M_EXT_RW;                         \
                (m)->m_ext.ext_size = (size);                           \
                (m)->m_ext.ext_free = NULL;                             \
                (m)->m_ext.ext_arg = NULL;                              \
                mowner_ref((m), M_EXT);                                 \
        }                                                               \
} while (0)

#define MEXTADD(m, buf, size, type, free, arg)                          \
do {                                                                    \
        MCLINITREFERENCE(m);                                            \
        (m)->m_data = (m)->m_ext.ext_buf = (char *)(buf);               \
        (m)->m_flags = ((m)->m_flags & ~M_EXTCOPYFLAGS) | M_EXT;        \
        (m)->m_ext.ext_size = (size);                                   \
        (m)->m_ext.ext_free = (free);                                   \
        (m)->m_ext.ext_arg = (arg);                                     \
        mowner_ref((m), M_EXT);                                         \
} while (0)

#define M_BUFADDR(m)                                                    \
        (((m)->m_flags & M_EXT) ? (m)->m_ext.ext_buf :                  \
            ((m)->m_flags & M_PKTHDR) ? (m)->m_pktdat : (m)->m_dat)

#define M_BUFSIZE(m)                                                    \
        (((m)->m_flags & M_EXT) ? (m)->m_ext.ext_size :                 \
            ((m)->m_flags & M_PKTHDR) ? MHLEN : MLEN)

#define MRESETDATA(m)   (m)->m_data = M_BUFADDR(m)

/*
 * Compute the offset of the beginning of the data buffer of a non-ext
 * mbuf.
 */
#define M_BUFOFFSET(m)                                                  \
        (((m)->m_flags & M_PKTHDR) ?                                    \
         offsetof(struct mbuf, m_pktdat) : offsetof(struct mbuf, m_dat))

/*
 * Determine if an mbuf's data area is read-only.  This is true
 * if external storage is read-only mapped, or not marked as R/W,
 * or referenced by more than one mbuf.
 */
#define M_READONLY(m)                                                   \
        (((m)->m_flags & M_EXT) != 0 &&                                 \
          (((m)->m_flags & (M_EXT_ROMAP|M_EXT_RW)) != M_EXT_RW ||       \
          (m)->m_ext.ext_refcnt > 1))

#define M_UNWRITABLE(__m, __len)                                        \
        ((__m)->m_len < (__len) || M_READONLY((__m)))

/*
 * Determine if an mbuf's data area is read-only at the MMU.
 */
#define M_ROMAP(m)                                                      \
        (((m)->m_flags & (M_EXT|M_EXT_ROMAP)) == (M_EXT|M_EXT_ROMAP))

/*
 * Compute the amount of space available before the current start of
 * data in an mbuf.
 */
#define M_LEADINGSPACE(m)                                               \
        (M_READONLY((m)) ? 0 : ((m)->m_data - M_BUFADDR(m)))

/*
 * Compute the amount of space available
 * after the end of data in an mbuf.
 */
#define _M_TRAILINGSPACE(m)                                             \
        ((m)->m_flags & M_EXT ? (m)->m_ext.ext_buf + (m)->m_ext.ext_size - \
         ((m)->m_data + (m)->m_len) :                                   \
         &(m)->m_dat[MLEN] - ((m)->m_data + (m)->m_len))

#define M_TRAILINGSPACE(m)                                              \
        (M_READONLY((m)) ? 0 : _M_TRAILINGSPACE((m)))

/*
 * Arrange to prepend space of size plen to mbuf m.
 * If a new mbuf must be allocated, how specifies whether to wait.
 * If how is M_DONTWAIT and allocation fails, the original mbuf chain
 * is freed and m is set to NULL.
 */
#define M_PREPEND(m, plen, how)                                         \
do {                                                                    \
        if (M_LEADINGSPACE(m) >= (plen)) {                              \
                (m)->m_data -= (plen);                                  \
                (m)->m_len += (plen);                                   \
        } else                                                          \
                (m) = m_prepend((m), (plen), (how));                    \
        if ((m) && (m)->m_flags & M_PKTHDR)                             \
                (m)->m_pkthdr.len += (plen);                            \
} while (0)

/* change mbuf to new type */
#define MCHTYPE(m, t)                                                   \
do {                                                                    \
        KASSERT((t) != MT_FREE);                                        \
        mbstat_type_add((m)->m_type, -1);                               \
        mbstat_type_add(t, 1);                                          \
        (m)->m_type = t;                                                \
} while (0)

#ifdef DIAGNOSTIC
#define M_VERIFY_PACKET(m)      m_verify_packet(m)
#else
#define M_VERIFY_PACKET(m)      __nothing
#endif

/* The "copy all" special length. */
#define M_COPYALL       -1

/*
 * Allow drivers and/or protocols to store private context information.
 */
#define M_GETCTX(m, t)          ((t)(m)->m_pkthdr._rcvif.ctx)
#define M_SETCTX(m, c)          ((void)((m)->m_pkthdr._rcvif.ctx = (void *)(c)))
#define M_CLEARCTX(m)           M_SETCTX((m), NULL)

/*
 * M_REGION_GET ensures that the "len"-sized region of type "typ" starting
 * from "off" within "m" is located in a single mbuf, contiguously.
 *
 * The pointer to the region will be returned to pointer variable "val".
 */
#define M_REGION_GET(val, typ, m, off, len) \
do {                                                                    \
        struct mbuf *_t;                                                \
        int _tmp;                                                       \
        if ((m)->m_len >= (off) + (len))                                \
                (val) = (typ)(mtod((m), char *) + (off));               \
        else {                                                          \
                _t = m_pulldown((m), (off), (len), &_tmp);              \
                if (_t) {                                               \
                        if (_t->m_len < _tmp + (len))                   \
                                panic("m_pulldown malfunction");        \
                        (val) = (typ)(mtod(_t, char *) + _tmp); \
                } else {                                                \
                        (val) = (typ)NULL;                              \
                        (m) = NULL;                                     \
                }                                                       \
        }                                                               \
} while (0)

#endif /* defined(_KERNEL) */

/*
 * Simple mbuf queueing system
 *
 * this is basically a SIMPLEQ adapted to mbuf use (ie using
 * m_nextpkt instead of field.sqe_next).
 *
 * m_next is ignored, so queueing chains of mbufs is possible
 */
#define MBUFQ_HEAD(name)                                        \
struct name {                                                   \
        struct mbuf *mq_first;                                  \
        struct mbuf **mq_last;                                  \
}

#define MBUFQ_INIT(q)           do {                            \
        (q)->mq_first = NULL;                                   \
        (q)->mq_last = &(q)->mq_first;                          \
} while (0)

#define MBUFQ_ENQUEUE(q, m)     do {                            \
        (m)->m_nextpkt = NULL;                                  \
        *(q)->mq_last = (m);                                    \
        (q)->mq_last = &(m)->m_nextpkt;                         \
} while (0)

#define MBUFQ_PREPEND(q, m)     do {                            \
        if (((m)->m_nextpkt = (q)->mq_first) == NULL)           \
                (q)->mq_last = &(m)->m_nextpkt;                 \
        (q)->mq_first = (m);                                    \
} while (0)

#define MBUFQ_DEQUEUE(q, m)     do {                            \
        if (((m) = (q)->mq_first) != NULL) {                    \
                if (((q)->mq_first = (m)->m_nextpkt) == NULL)   \
                        (q)->mq_last = &(q)->mq_first;          \
                else                                            \
                        (m)->m_nextpkt = NULL;                  \
        }                                                       \
} while (0)

#define MBUFQ_DRAIN(q)          do {                            \
        struct mbuf *__m0;                                      \
        while ((__m0 = (q)->mq_first) != NULL) {                \
                (q)->mq_first = __m0->m_nextpkt;                \
                m_freem(__m0);                                  \
        }                                                       \
        (q)->mq_last = &(q)->mq_first;                          \
} while (0)

#define MBUFQ_FIRST(q)          ((q)->mq_first)
#define MBUFQ_NEXT(m)           ((m)->m_nextpkt)
#define MBUFQ_LAST(q)           (*(q)->mq_last)

/*
 * Mbuf statistics.
 * For statistics related to mbuf and cluster allocations, see also the
 * pool headers (mb_cache and mcl_cache).
 */
struct mbstat {
        u_long  _m_spare;       /* formerly m_mbufs */
        u_long  _m_spare1;      /* formerly m_clusters */
        u_long  _m_spare2;      /* spare field */
        u_long  _m_spare3;      /* formely m_clfree - free clusters */
        u_long  m_drops;        /* times failed to find space */
        u_long  m_wait;         /* times waited for space */
        u_long  m_drain;        /* times drained protocols for space */
        u_short m_mtypes[256];  /* type specific mbuf allocations */
};

struct mbstat_cpu {
        u_int   m_mtypes[256];  /* type specific mbuf allocations */
};

/*
 * Mbuf sysctl variables.
 */
#define MBUF_MSIZE              1       /* int: mbuf base size */
#define MBUF_MCLBYTES           2       /* int: mbuf cluster size */
#define MBUF_NMBCLUSTERS        3       /* int: limit on the # of clusters */
#define MBUF_MBLOWAT            4       /* int: mbuf low water mark */
#define MBUF_MCLLOWAT           5       /* int: mbuf cluster low water mark */
#define MBUF_STATS              6       /* struct: mbstat */
#define MBUF_MOWNERS            7       /* struct: m_owner[] */
#define MBUF_NMBCLUSTERS_LIMIT  8       /* int: limit of nmbclusters */

#ifdef _KERNEL
extern struct mbstat mbstat;
extern int nmbclusters;         /* limit on the # of clusters */
extern int mblowat;             /* mbuf low water mark */
extern int mcllowat;            /* mbuf cluster low water mark */
extern int max_linkhdr;         /* largest link-level header */
extern int max_protohdr;                /* largest protocol header */
extern int max_hdr;             /* largest link+protocol header */
extern int max_datalen;         /* MHLEN - max_hdr */
extern const int msize;                 /* mbuf base size */
extern const int mclbytes;              /* mbuf cluster size */
extern pool_cache_t mb_cache;
#ifdef MBUFTRACE
LIST_HEAD(mownerhead, mowner);
extern struct mownerhead mowners;
extern struct mowner unknown_mowners[];
extern struct mowner revoked_mowner;
#endif

MALLOC_DECLARE(M_MBUF);
MALLOC_DECLARE(M_SONAME);

struct  mbuf *m_copym(struct mbuf *, int, int, int);
struct  mbuf *m_copypacket(struct mbuf *, int);
struct  mbuf *m_devget(char *, int, int, struct ifnet *);
struct  mbuf *m_dup(struct mbuf *, int, int, int);
struct  mbuf *m_get(int, int);
struct  mbuf *m_gethdr(int, int);
struct  mbuf *m_get_n(int, int, size_t, size_t);
struct  mbuf *m_gethdr_n(int, int, size_t, size_t);
struct  mbuf *m_prepend(struct mbuf *,int, int);
struct  mbuf *m_pulldown(struct mbuf *, int, int, int *);
struct  mbuf *m_pullup(struct mbuf *, int);
struct  mbuf *m_copyup(struct mbuf *, int, int);
struct  mbuf *m_split(struct mbuf *,int, int);
struct  mbuf *m_getptr(struct mbuf *, int, int *);
void    m_adj(struct mbuf *, int);
struct  mbuf *m_defrag(struct mbuf *, int);
int     m_apply(struct mbuf *, int, int,
    int (*)(void *, void *, unsigned int), void *);
void    m_cat(struct mbuf *,struct mbuf *);
void    m_clget(struct mbuf *, int);
void    m_copyback(struct mbuf *, int, int, const void *);
struct  mbuf *m_copyback_cow(struct mbuf *, int, int, const void *, int);
int     m_makewritable(struct mbuf **, int, int, int);
struct  mbuf *m_getcl(int, int, int);
void    m_copydata(struct mbuf *, int, int, void *);
void    m_verify_packet(struct mbuf *);
struct  mbuf *m_free(struct mbuf *);
void    m_freem(struct mbuf *);
void    mbinit(void);
void    m_remove_pkthdr(struct mbuf *);
void    m_copy_pkthdr(struct mbuf *, struct mbuf *);
void    m_move_pkthdr(struct mbuf *, struct mbuf *);
void    m_align(struct mbuf *, int);

bool    m_ensure_contig(struct mbuf **, int);
struct mbuf *m_add(struct mbuf *, struct mbuf *);

/* Inline routines. */
static __inline u_int m_length(const struct mbuf *) __unused;

/* Statistics */
void mbstat_type_add(int, int);

/* Packet tag routines */
struct  m_tag *m_tag_get(int, int, int);
void    m_tag_free(struct m_tag *);
void    m_tag_prepend(struct mbuf *, struct m_tag *);
void    m_tag_unlink(struct mbuf *, struct m_tag *);
void    m_tag_delete(struct mbuf *, struct m_tag *);
void    m_tag_delete_chain(struct mbuf *);
struct  m_tag *m_tag_find(const struct mbuf *, int);
struct  m_tag *m_tag_copy(struct m_tag *);
int     m_tag_copy_chain(struct mbuf *, struct mbuf *);

/* Packet tag types */
#define PACKET_TAG_NONE                 0  /* Nothing */
#define PACKET_TAG_SO                   4  /* sending socket pointer */
#define PACKET_TAG_NPF                  10 /* packet filter */
#define PACKET_TAG_PF                   11 /* packet filter */
#define PACKET_TAG_ALTQ_QID             12 /* ALTQ queue id */
#define PACKET_TAG_IPSEC_OUT_DONE       18
#define PACKET_TAG_IPSEC_NAT_T_PORTS    25 /* two uint16_t */
#define PACKET_TAG_INET6                26 /* IPv6 info */
#define PACKET_TAG_TUNNEL_INFO          28 /* tunnel identification and
                                            * protocol callback, for loop
                                            * detection/recovery
                                            */
#define PACKET_TAG_MPLS                 29 /* Indicate it's for MPLS */
#define PACKET_TAG_SRCROUTE             30 /* IPv4 source routing */
#define PACKET_TAG_ETHERNET_SRC         31 /* Ethernet source address */

/*
 * Return the number of bytes in the mbuf chain, m.
 */
static __inline u_int
m_length(const struct mbuf *m)
{
        const struct mbuf *m0;
        u_int pktlen;

        if ((m->m_flags & M_PKTHDR) != 0)
                return m->m_pkthdr.len;

        pktlen = 0;
        for (m0 = m; m0 != NULL; m0 = m0->m_next)
                pktlen += m0->m_len;
        return pktlen;
}

static __inline void
m_set_rcvif(struct mbuf *m, const struct ifnet *ifp)
{
        KASSERT(m->m_flags & M_PKTHDR);
        m->m_pkthdr.rcvif_index = ifp->if_index;
}

static __inline void
m_reset_rcvif(struct mbuf *m)
{
        KASSERT(m->m_flags & M_PKTHDR);
        /* A caller may expect whole _rcvif union is zeroed */
        /* m->m_pkthdr.rcvif_index = 0; */
        m->m_pkthdr._rcvif.ctx = NULL;
}

static __inline void
m_copy_rcvif(struct mbuf *m, const struct mbuf *n)
{
        KASSERT(m->m_flags & M_PKTHDR);
        KASSERT(n->m_flags & M_PKTHDR);
        m->m_pkthdr.rcvif_index = n->m_pkthdr.rcvif_index;
}

#define M_GET_ALIGNED_HDR(m, type, linkhdr) \
    m_get_aligned_hdr((m), __alignof(type) - 1, sizeof(type), (linkhdr))

static __inline int
m_get_aligned_hdr(struct mbuf **m, int mask, size_t hlen, bool linkhdr)
{
#ifndef __NO_STRICT_ALIGNMENT
        if (((uintptr_t)mtod(*m, void *) & mask) != 0)
                *m = m_copyup(*m, hlen, 
                      linkhdr ? (max_linkhdr + mask) & ~mask : 0);
        else
#endif
        if (__predict_false((size_t)(*m)->m_len < hlen))
                *m = m_pullup(*m, hlen);

        return *m == NULL;
}

void m_print(const struct mbuf *, const char *, void (*)(const char *, ...)
    __printflike(1, 2));

/* from uipc_mbufdebug.c */
void    m_examine(const struct mbuf *, int, const char *,
    void (*)(const char *, ...) __printflike(1, 2));

/* parsers for m_examine() */
void m_examine_ether(const struct mbuf *, int, const char *,
    void (*)(const char *, ...) __printflike(1, 2));
void m_examine_pppoe(const struct mbuf *, int, const char *,
    void (*)(const char *, ...) __printflike(1, 2));
void m_examine_ppp(const struct mbuf *, int, const char *,
    void (*)(const char *, ...) __printflike(1, 2));
void m_examine_arp(const struct mbuf *, int, const char *,
    void (*)(const char *, ...) __printflike(1, 2));
void m_examine_ip(const struct mbuf *, int, const char *,
    void (*)(const char *, ...) __printflike(1, 2));
void m_examine_icmp(const struct mbuf *, int, const char *,
    void (*)(const char *, ...) __printflike(1, 2));
void m_examine_ip6(const struct mbuf *, int, const char *,
    void (*)(const char *, ...) __printflike(1, 2));
void m_examine_icmp6(const struct mbuf *, int, const char *,
    void (*)(const char *, ...) __printflike(1, 2));
void m_examine_tcp(const struct mbuf *, int, const char *,
    void (*)(const char *, ...) __printflike(1, 2));
void m_examine_udp(const struct mbuf *, int, const char *,
    void (*)(const char *, ...) __printflike(1, 2));
void m_examine_hex(const struct mbuf *, int, const char *,
    void (*)(const char *, ...) __printflike(1, 2));

/*
 * Get rcvif of a mbuf.
 *
 * The caller must call m_put_rcvif after using rcvif if the returned rcvif
 * isn't NULL. If the returned rcvif is NULL, the caller doesn't need to call
 * m_put_rcvif (although calling it is safe).
 *
 * The caller must not block or sleep while using rcvif. The API ensures a
 * returned rcvif isn't freed until m_put_rcvif is called.
 */
static __inline struct ifnet *
m_get_rcvif(const struct mbuf *m, int *s)
{
        struct ifnet *ifp;

        KASSERT(m->m_flags & M_PKTHDR);
        *s = pserialize_read_enter();
        ifp = if_byindex(m->m_pkthdr.rcvif_index);
        if (__predict_false(ifp == NULL))
                pserialize_read_exit(*s);

        return ifp;
}

static __inline void
m_put_rcvif(struct ifnet *ifp, int *s)
{

        if (ifp == NULL)
                return;
        pserialize_read_exit(*s);
}

/*
 * Get rcvif of a mbuf.
 *
 * The caller must call m_put_rcvif_psref after using rcvif. The API ensures
 * a got rcvif isn't be freed until m_put_rcvif_psref is called.
 */
static __inline struct ifnet *
m_get_rcvif_psref(const struct mbuf *m, struct psref *psref)
{
        KASSERT(m->m_flags & M_PKTHDR);
        return if_get_byindex(m->m_pkthdr.rcvif_index, psref);
}

static __inline void
m_put_rcvif_psref(struct ifnet *ifp, struct psref *psref)
{

        if (ifp == NULL)
                return;
        if_put(ifp, psref);
}

/*
 * Get rcvif of a mbuf.
 *
 * This is NOT an MP-safe API and shouldn't be used at where we want MP-safe.
 */
static __inline struct ifnet *
m_get_rcvif_NOMPSAFE(const struct mbuf *m)
{
        KASSERT(m->m_flags & M_PKTHDR);
        return if_byindex(m->m_pkthdr.rcvif_index);
}

#endif /* _KERNEL */
#endif /* !_SYS_MBUF_H_ */