FreeBSD/Linux Kernel Cross Reference
sys/net/if_var.h

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 1982, 1986, 1989, 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.
     *
     *      From: @(#)if.h  8.1 (Berkeley) 6/10/93
     * $FreeBSD: releng/12.0/sys/net/if_var.h 339012 2018-09-29 13:01:23Z tuexen $
     */
    
    #ifndef _NET_IF_VAR_H_
    #define _NET_IF_VAR_H_
    
    /*
     * Structures defining a network interface, providing a packet
     * transport mechanism (ala level 0 of the PUP protocols).
     *
     * Each interface accepts output datagrams of a specified maximum
     * length, and provides higher level routines with input datagrams
     * received from its medium.
     *
     * Output occurs when the routine if_output is called, with three parameters:
     *      (*ifp->if_output)(ifp, m, dst, rt)
     * Here m is the mbuf chain to be sent and dst is the destination address.
     * The output routine encapsulates the supplied datagram if necessary,
     * and then transmits it on its medium.
     *
     * On input, each interface unwraps the data received by it, and either
     * places it on the input queue of an internetwork datagram routine
     * and posts the associated software interrupt, or passes the datagram to a raw
     * packet input routine.
     *
     * Routines exist for locating interfaces by their addresses
     * or for locating an interface on a certain network, as well as more general
     * routing and gateway routines maintaining information used to locate
     * interfaces.  These routines live in the files if.c and route.c
     */
    
    struct  rtentry;                /* ifa_rtrequest */
    struct  rt_addrinfo;            /* ifa_rtrequest */
    struct  socket;
    struct  carp_if;
    struct  carp_softc;
    struct  ifvlantrunk;
    struct  route;                  /* if_output */
    struct  vnet;
    struct  ifmedia;
    struct  netmap_adapter;
    struct  netdump_methods;
    
    #ifdef _KERNEL
    #include <sys/mbuf.h>           /* ifqueue only? */
    #include <sys/buf_ring.h>
    #include <net/vnet.h>
    #endif /* _KERNEL */
    #include <sys/ck.h>
    #include <sys/counter.h>
    #include <sys/epoch.h>
    #include <sys/lock.h>           /* XXX */
    #include <sys/mutex.h>          /* struct ifqueue */
    #include <sys/rwlock.h>         /* XXX */
    #include <sys/sx.h>             /* XXX */
    #include <sys/_task.h>          /* if_link_task */
    #define IF_DUNIT_NONE   -1
    
    #include <net/altq/if_altq.h>
    
    CK_STAILQ_HEAD(ifnethead, ifnet);       /* we use TAILQs so that the order of */
    CK_STAILQ_HEAD(ifaddrhead, ifaddr);     /* instantiation is preserved in the list */
    CK_STAILQ_HEAD(ifmultihead, ifmultiaddr);
    CK_STAILQ_HEAD(ifgrouphead, ifg_group);
    
    #ifdef _KERNEL
    VNET_DECLARE(struct pfil_head, link_pfil_hook); /* packet filter hooks */
    #define V_link_pfil_hook        VNET(link_pfil_hook)
   
   #define HHOOK_IPSEC_INET        0
   #define HHOOK_IPSEC_INET6       1
   #define HHOOK_IPSEC_COUNT       2
   VNET_DECLARE(struct hhook_head *, ipsec_hhh_in[HHOOK_IPSEC_COUNT]);
   VNET_DECLARE(struct hhook_head *, ipsec_hhh_out[HHOOK_IPSEC_COUNT]);
   #define V_ipsec_hhh_in  VNET(ipsec_hhh_in)
   #define V_ipsec_hhh_out VNET(ipsec_hhh_out)
   extern epoch_t net_epoch_preempt;
   extern epoch_t net_epoch;
   #endif /* _KERNEL */
   
   typedef enum {
           IFCOUNTER_IPACKETS = 0,
           IFCOUNTER_IERRORS,
           IFCOUNTER_OPACKETS,
           IFCOUNTER_OERRORS,
           IFCOUNTER_COLLISIONS,
           IFCOUNTER_IBYTES,
           IFCOUNTER_OBYTES,
           IFCOUNTER_IMCASTS,
           IFCOUNTER_OMCASTS,
           IFCOUNTER_IQDROPS,
           IFCOUNTER_OQDROPS,
           IFCOUNTER_NOPROTO,
           IFCOUNTERS /* Array size. */
   } ift_counter;
   
   typedef struct ifnet * if_t;
   
   typedef void (*if_start_fn_t)(if_t);
   typedef int (*if_ioctl_fn_t)(if_t, u_long, caddr_t);
   typedef void (*if_init_fn_t)(void *);
   typedef void (*if_qflush_fn_t)(if_t);
   typedef int (*if_transmit_fn_t)(if_t, struct mbuf *);
   typedef uint64_t (*if_get_counter_t)(if_t, ift_counter);
   
   struct ifnet_hw_tsomax {
           u_int   tsomaxbytes;    /* TSO total burst length limit in bytes */
           u_int   tsomaxsegcount; /* TSO maximum segment count */
           u_int   tsomaxsegsize;  /* TSO maximum segment size in bytes */
   };
   
   /* Interface encap request types */
   typedef enum {
           IFENCAP_LL = 1                  /* pre-calculate link-layer header */
   } ife_type;
   
   /*
    * The structure below allows to request various pre-calculated L2/L3 headers
    * for different media. Requests varies by type (rtype field).
    *
    * IFENCAP_LL type: pre-calculates link header based on address family
    *   and destination lladdr.
    *
    *   Input data fields:
    *     buf: pointer to destination buffer
    *     bufsize: buffer size
    *     flags: IFENCAP_FLAG_BROADCAST if destination is broadcast
    *     family: address family defined by AF_ constant.
    *     lladdr: pointer to link-layer address
    *     lladdr_len: length of link-layer address
    *     hdata: pointer to L3 header (optional, used for ARP requests).
    *   Output data fields:
    *     buf: encap data is stored here
    *     bufsize: resulting encap length is stored here
    *     lladdr_off: offset of link-layer address from encap hdr start
    *     hdata: L3 header may be altered if necessary
    */
   
   struct if_encap_req {
           u_char          *buf;           /* Destination buffer (w) */
           size_t          bufsize;        /* size of provided buffer (r) */
           ife_type        rtype;          /* request type (r) */
           uint32_t        flags;          /* Request flags (r) */
           int             family;         /* Address family AF_* (r) */
           int             lladdr_off;     /* offset from header start (w) */
           int             lladdr_len;     /* lladdr length (r) */
           char            *lladdr;        /* link-level address pointer (r) */
           char            *hdata;         /* Upper layer header data (rw) */
   };
   
   #define IFENCAP_FLAG_BROADCAST  0x02    /* Destination is broadcast */
   
   /*
    * Network interface send tag support. The storage of "struct
    * m_snd_tag" comes from the network driver and it is free to allocate
    * as much additional space as it wants for its own use.
    */
   struct m_snd_tag;
   
   #define IF_SND_TAG_TYPE_RATE_LIMIT 0
   #define IF_SND_TAG_TYPE_UNLIMITED 1
   #define IF_SND_TAG_TYPE_MAX 2
   
   struct if_snd_tag_alloc_header {
           uint32_t type;          /* send tag type, see IF_SND_TAG_XXX */
           uint32_t flowid;        /* mbuf hash value */
           uint32_t flowtype;      /* mbuf hash type */
   };
   
   struct if_snd_tag_alloc_rate_limit {
           struct if_snd_tag_alloc_header hdr;
           uint64_t max_rate;      /* in bytes/s */
   };
   
   struct if_snd_tag_rate_limit_params {
           uint64_t max_rate;      /* in bytes/s */
           uint32_t queue_level;   /* 0 (empty) .. 65535 (full) */
   #define IF_SND_QUEUE_LEVEL_MIN 0
   #define IF_SND_QUEUE_LEVEL_MAX 65535
           uint32_t reserved;      /* padding */
   };
   
   union if_snd_tag_alloc_params {
           struct if_snd_tag_alloc_header hdr;
           struct if_snd_tag_alloc_rate_limit rate_limit;
           struct if_snd_tag_alloc_rate_limit unlimited;
   };
   
   union if_snd_tag_modify_params {
           struct if_snd_tag_rate_limit_params rate_limit;
           struct if_snd_tag_rate_limit_params unlimited;
   };
   
   union if_snd_tag_query_params {
           struct if_snd_tag_rate_limit_params rate_limit;
           struct if_snd_tag_rate_limit_params unlimited;
   };
   
   typedef int (if_snd_tag_alloc_t)(struct ifnet *, union if_snd_tag_alloc_params *,
       struct m_snd_tag **);
   typedef int (if_snd_tag_modify_t)(struct m_snd_tag *, union if_snd_tag_modify_params *);
   typedef int (if_snd_tag_query_t)(struct m_snd_tag *, union if_snd_tag_query_params *);
   typedef void (if_snd_tag_free_t)(struct m_snd_tag *);
   
   /*
    * Structure defining a network interface.
    */
   struct ifnet {
           /* General book keeping of interface lists. */
           CK_STAILQ_ENTRY(ifnet) if_link;         /* all struct ifnets are chained (CK_) */
           LIST_ENTRY(ifnet) if_clones;    /* interfaces of a cloner */
           CK_STAILQ_HEAD(, ifg_list) if_groups; /* linked list of groups per if (CK_) */
                                           /* protected by if_addr_lock */
           u_char  if_alloctype;           /* if_type at time of allocation */
   
           /* Driver and protocol specific information that remains stable. */
           void    *if_softc;              /* pointer to driver state */
           void    *if_llsoftc;            /* link layer softc */
           void    *if_l2com;              /* pointer to protocol bits */
           const char *if_dname;           /* driver name */
           int     if_dunit;               /* unit or IF_DUNIT_NONE */
           u_short if_index;               /* numeric abbreviation for this if  */
           short   if_index_reserved;      /* spare space to grow if_index */
           char    if_xname[IFNAMSIZ];     /* external name (name + unit) */
           char    *if_description;        /* interface description */
   
           /* Variable fields that are touched by the stack and drivers. */
           int     if_flags;               /* up/down, broadcast, etc. */
           int     if_drv_flags;           /* driver-managed status flags */
           int     if_capabilities;        /* interface features & capabilities */
           int     if_capenable;           /* enabled features & capabilities */
           void    *if_linkmib;            /* link-type-specific MIB data */
           size_t  if_linkmiblen;          /* length of above data */
           u_int   if_refcount;            /* reference count */
   
           /* These fields are shared with struct if_data. */
           uint8_t         if_type;        /* ethernet, tokenring, etc */
           uint8_t         if_addrlen;     /* media address length */
           uint8_t         if_hdrlen;      /* media header length */
           uint8_t         if_link_state;  /* current link state */
           uint32_t        if_mtu;         /* maximum transmission unit */
           uint32_t        if_metric;      /* routing metric (external only) */
           uint64_t        if_baudrate;    /* linespeed */
           uint64_t        if_hwassist;    /* HW offload capabilities, see IFCAP */
           time_t          if_epoch;       /* uptime at attach or stat reset */
           struct timeval  if_lastchange;  /* time of last administrative change */
   
           struct  ifaltq if_snd;          /* output queue (includes altq) */
           struct  task if_linktask;       /* task for link change events */
   
           /* Addresses of different protocol families assigned to this if. */
           struct mtx if_addr_lock;        /* lock to protect address lists */
                   /*
                    * if_addrhead is the list of all addresses associated to
                    * an interface.
                    * Some code in the kernel assumes that first element
                    * of the list has type AF_LINK, and contains sockaddr_dl
                    * addresses which store the link-level address and the name
                    * of the interface.
                    * However, access to the AF_LINK address through this
                    * field is deprecated. Use if_addr or ifaddr_byindex() instead.
                    */
           struct  ifaddrhead if_addrhead; /* linked list of addresses per if */
           struct  ifmultihead if_multiaddrs; /* multicast addresses configured */
           int     if_amcount;             /* number of all-multicast requests */
           struct  ifaddr  *if_addr;       /* pointer to link-level address */
           void    *if_hw_addr;            /* hardware link-level address */
           const u_int8_t *if_broadcastaddr; /* linklevel broadcast bytestring */
           struct  mtx if_afdata_lock;
           void    *if_afdata[AF_MAX];
           int     if_afdata_initialized;
   
           /* Additional features hung off the interface. */
           u_int   if_fib;                 /* interface FIB */
           struct  vnet *if_vnet;          /* pointer to network stack instance */
           struct  vnet *if_home_vnet;     /* where this ifnet originates from */
           struct  ifvlantrunk *if_vlantrunk; /* pointer to 802.1q data */
           struct  bpf_if *if_bpf;         /* packet filter structure */
           int     if_pcount;              /* number of promiscuous listeners */
           void    *if_bridge;             /* bridge glue */
           void    *if_lagg;               /* lagg glue */
           void    *if_pf_kif;             /* pf glue */
           struct  carp_if *if_carp;       /* carp interface structure */
           struct  label *if_label;        /* interface MAC label */
           struct  netmap_adapter *if_netmap; /* netmap(4) softc */
   
           /* Various procedures of the layer2 encapsulation and drivers. */
           int     (*if_output)            /* output routine (enqueue) */
                   (struct ifnet *, struct mbuf *, const struct sockaddr *,
                        struct route *);
           void    (*if_input)             /* input routine (from h/w driver) */
                   (struct ifnet *, struct mbuf *);
           struct mbuf *(*if_bridge_input)(struct ifnet *, struct mbuf *);
           int     (*if_bridge_output)(struct ifnet *, struct mbuf *, struct sockaddr *,
                       struct rtentry *);
           void (*if_bridge_linkstate)(struct ifnet *ifp);
           if_start_fn_t   if_start;       /* initiate output routine */
           if_ioctl_fn_t   if_ioctl;       /* ioctl routine */
           if_init_fn_t    if_init;        /* Init routine */
           int     (*if_resolvemulti)      /* validate/resolve multicast */
                   (struct ifnet *, struct sockaddr **, struct sockaddr *);
           if_qflush_fn_t  if_qflush;      /* flush any queue */   
           if_transmit_fn_t if_transmit;   /* initiate output routine */
   
           void    (*if_reassign)          /* reassign to vnet routine */
                   (struct ifnet *, struct vnet *, char *);
           if_get_counter_t if_get_counter; /* get counter values */
           int     (*if_requestencap)      /* make link header from request */
                   (struct ifnet *, struct if_encap_req *);
   
           /* Statistics. */
           counter_u64_t   if_counters[IFCOUNTERS];
   
           /* Stuff that's only temporary and doesn't belong here. */
   
           /*
            * Network adapter TSO limits:
            * ===========================
            *
            * If the "if_hw_tsomax" field is zero the maximum segment
            * length limit does not apply. If the "if_hw_tsomaxsegcount"
            * or the "if_hw_tsomaxsegsize" field is zero the TSO segment
            * count limit does not apply. If all three fields are zero,
            * there is no TSO limit.
            *
            * NOTE: The TSO limits should reflect the values used in the
            * BUSDMA tag a network adapter is using to load a mbuf chain
            * for transmission. The TCP/IP network stack will subtract
            * space for all linklevel and protocol level headers and
            * ensure that the full mbuf chain passed to the network
            * adapter fits within the given limits.
            */
           u_int   if_hw_tsomax;           /* TSO maximum size in bytes */
           u_int   if_hw_tsomaxsegcount;   /* TSO maximum segment count */
           u_int   if_hw_tsomaxsegsize;    /* TSO maximum segment size in bytes */
   
           /*
            * Network adapter send tag support:
            */
           if_snd_tag_alloc_t *if_snd_tag_alloc;
           if_snd_tag_modify_t *if_snd_tag_modify;
           if_snd_tag_query_t *if_snd_tag_query;
           if_snd_tag_free_t *if_snd_tag_free;
   
           /* Ethernet PCP */
           uint8_t if_pcp;
   
           /*
            * Netdump hooks to be called while dumping.
            */
           struct netdump_methods *if_netdump_methods;
           struct epoch_context    if_epoch_ctx;
           struct epoch_tracker    if_addr_et;
           struct epoch_tracker    if_maddr_et;
   
           /*
            * Spare fields to be added before branching a stable branch, so
            * that structure can be enhanced without changing the kernel
            * binary interface.
            */
           int     if_ispare[4];           /* general use */
   };
   
   /* for compatibility with other BSDs */
   #define if_name(ifp)    ((ifp)->if_xname)
   
   /*
    * Locks for address lists on the network interface.
    */
   #define IF_ADDR_LOCK_INIT(if)   mtx_init(&(if)->if_addr_lock, "if_addr_lock", NULL, MTX_DEF)
   #define IF_ADDR_LOCK_DESTROY(if)        mtx_destroy(&(if)->if_addr_lock)
   #define IF_ADDR_RLOCK(if)       struct epoch_tracker if_addr_et; epoch_enter_preempt(net_epoch_preempt, &if_addr_et);
   #define IF_ADDR_RUNLOCK(if)     epoch_exit_preempt(net_epoch_preempt, &if_addr_et);
   
   #define IF_ADDR_WLOCK(if)       mtx_lock(&(if)->if_addr_lock)
   #define IF_ADDR_WUNLOCK(if)     mtx_unlock(&(if)->if_addr_lock)
   #define IF_ADDR_LOCK_ASSERT(if) MPASS(in_epoch(net_epoch_preempt) || mtx_owned(&(if)->if_addr_lock))
   #define IF_ADDR_WLOCK_ASSERT(if) mtx_assert(&(if)->if_addr_lock, MA_OWNED)
   #define NET_EPOCH_ENTER() struct epoch_tracker nep_et; epoch_enter_preempt(net_epoch_preempt, &nep_et)
   #define NET_EPOCH_ENTER_ET(et) epoch_enter_preempt(net_epoch_preempt, &(et))
   #define NET_EPOCH_EXIT() epoch_exit_preempt(net_epoch_preempt, &nep_et)
   #define NET_EPOCH_EXIT_ET(et) epoch_exit_preempt(net_epoch_preempt, &(et))
   #define NET_EPOCH_WAIT() epoch_wait_preempt(net_epoch_preempt)
   
   
   /*
    * Function variations on locking macros intended to be used by loadable
    * kernel modules in order to divorce them from the internals of address list
    * locking.
    */
   void    if_addr_rlock(struct ifnet *ifp);       /* if_addrhead */
   void    if_addr_runlock(struct ifnet *ifp);     /* if_addrhead */
   void    if_maddr_rlock(if_t ifp);       /* if_multiaddrs */
   void    if_maddr_runlock(if_t ifp);     /* if_multiaddrs */
   
   #ifdef _KERNEL
   #ifdef _SYS_EVENTHANDLER_H_
   /* interface link layer address change event */
   typedef void (*iflladdr_event_handler_t)(void *, struct ifnet *);
   EVENTHANDLER_DECLARE(iflladdr_event, iflladdr_event_handler_t);
   /* interface address change event */
   typedef void (*ifaddr_event_handler_t)(void *, struct ifnet *);
   EVENTHANDLER_DECLARE(ifaddr_event, ifaddr_event_handler_t);
   /* new interface arrival event */
   typedef void (*ifnet_arrival_event_handler_t)(void *, struct ifnet *);
   EVENTHANDLER_DECLARE(ifnet_arrival_event, ifnet_arrival_event_handler_t);
   /* interface departure event */
   typedef void (*ifnet_departure_event_handler_t)(void *, struct ifnet *);
   EVENTHANDLER_DECLARE(ifnet_departure_event, ifnet_departure_event_handler_t);
   /* Interface link state change event */
   typedef void (*ifnet_link_event_handler_t)(void *, struct ifnet *, int);
   EVENTHANDLER_DECLARE(ifnet_link_event, ifnet_link_event_handler_t);
   /* Interface up/down event */
   #define IFNET_EVENT_UP          0
   #define IFNET_EVENT_DOWN        1
   #define IFNET_EVENT_PCP         2       /* priority code point, PCP */
   
   typedef void (*ifnet_event_fn)(void *, struct ifnet *ifp, int event);
   EVENTHANDLER_DECLARE(ifnet_event, ifnet_event_fn);
   #endif /* _SYS_EVENTHANDLER_H_ */
   
   /*
    * interface groups
    */
   struct ifg_group {
           char                             ifg_group[IFNAMSIZ];
           u_int                            ifg_refcnt;
           void                            *ifg_pf_kif;
           CK_STAILQ_HEAD(, ifg_member)     ifg_members; /* (CK_) */
           CK_STAILQ_ENTRY(ifg_group)               ifg_next; /* (CK_) */
   };
   
   struct ifg_member {
           CK_STAILQ_ENTRY(ifg_member)      ifgm_next; /* (CK_) */
           struct ifnet            *ifgm_ifp;
   };
   
   struct ifg_list {
           struct ifg_group        *ifgl_group;
           CK_STAILQ_ENTRY(ifg_list)        ifgl_next; /* (CK_) */
   };
   
   #ifdef _SYS_EVENTHANDLER_H_
   /* group attach event */
   typedef void (*group_attach_event_handler_t)(void *, struct ifg_group *);
   EVENTHANDLER_DECLARE(group_attach_event, group_attach_event_handler_t);
   /* group detach event */
   typedef void (*group_detach_event_handler_t)(void *, struct ifg_group *);
   EVENTHANDLER_DECLARE(group_detach_event, group_detach_event_handler_t);
   /* group change event */
   typedef void (*group_change_event_handler_t)(void *, const char *);
   EVENTHANDLER_DECLARE(group_change_event, group_change_event_handler_t);
   #endif /* _SYS_EVENTHANDLER_H_ */
   
   #define IF_AFDATA_LOCK_INIT(ifp)        \
           mtx_init(&(ifp)->if_afdata_lock, "if_afdata", NULL, MTX_DEF)
   
   #define IF_AFDATA_WLOCK(ifp)    mtx_lock(&(ifp)->if_afdata_lock)
   #define IF_AFDATA_RLOCK(ifp)    struct epoch_tracker if_afdata_et; epoch_enter_preempt(net_epoch_preempt, &if_afdata_et)
   #define IF_AFDATA_WUNLOCK(ifp)  mtx_unlock(&(ifp)->if_afdata_lock)
   #define IF_AFDATA_RUNLOCK(ifp)  epoch_exit_preempt(net_epoch_preempt, &if_afdata_et)
   #define IF_AFDATA_LOCK(ifp)     IF_AFDATA_WLOCK(ifp)
   #define IF_AFDATA_UNLOCK(ifp)   IF_AFDATA_WUNLOCK(ifp)
   #define IF_AFDATA_TRYLOCK(ifp)  mtx_trylock(&(ifp)->if_afdata_lock)
   #define IF_AFDATA_DESTROY(ifp)  mtx_destroy(&(ifp)->if_afdata_lock)
   
   #define IF_AFDATA_LOCK_ASSERT(ifp)      MPASS(in_epoch(net_epoch_preempt) || mtx_owned(&(ifp)->if_afdata_lock))
   #define IF_AFDATA_RLOCK_ASSERT(ifp)     MPASS(in_epoch(net_epoch_preempt));
   #define IF_AFDATA_WLOCK_ASSERT(ifp)     mtx_assert(&(ifp)->if_afdata_lock, MA_OWNED)
   #define IF_AFDATA_UNLOCK_ASSERT(ifp)    mtx_assert(&(ifp)->if_afdata_lock, MA_NOTOWNED)
   
   /*
    * 72 was chosen below because it is the size of a TCP/IP
    * header (40) + the minimum mss (32).
    */
   #define IF_MINMTU       72
   #define IF_MAXMTU       65535
   
   #define TOEDEV(ifp)     ((ifp)->if_llsoftc)
   
   /*
    * The ifaddr structure contains information about one address
    * of an interface.  They are maintained by the different address families,
    * are allocated and attached when an address is set, and are linked
    * together so all addresses for an interface can be located.
    *
    * NOTE: a 'struct ifaddr' is always at the beginning of a larger
    * chunk of malloc'ed memory, where we store the three addresses
    * (ifa_addr, ifa_dstaddr and ifa_netmask) referenced here.
    */
   struct ifaddr {
           struct  sockaddr *ifa_addr;     /* address of interface */
           struct  sockaddr *ifa_dstaddr;  /* other end of p-to-p link */
   #define ifa_broadaddr   ifa_dstaddr     /* broadcast address interface */
           struct  sockaddr *ifa_netmask;  /* used to determine subnet */
           struct  ifnet *ifa_ifp;         /* back-pointer to interface */
           struct  carp_softc *ifa_carp;   /* pointer to CARP data */
           CK_STAILQ_ENTRY(ifaddr) ifa_link;       /* queue macro glue */
           void    (*ifa_rtrequest)        /* check or clean routes (+ or -)'d */
                   (int, struct rtentry *, struct rt_addrinfo *);
           u_short ifa_flags;              /* mostly rt_flags for cloning */
   #define IFA_ROUTE       RTF_UP          /* route installed */
   #define IFA_RTSELF      RTF_HOST        /* loopback route to self installed */
           u_int   ifa_refcnt;             /* references to this structure */
   
           counter_u64_t   ifa_ipackets;
           counter_u64_t   ifa_opackets;    
           counter_u64_t   ifa_ibytes;
           counter_u64_t   ifa_obytes;
           struct  epoch_context   ifa_epoch_ctx;
   };
   
   struct ifaddr * ifa_alloc(size_t size, int flags);
   void    ifa_free(struct ifaddr *ifa);
   void    ifa_ref(struct ifaddr *ifa);
   
   /*
    * Multicast address structure.  This is analogous to the ifaddr
    * structure except that it keeps track of multicast addresses.
    */
   #define IFMA_F_ENQUEUED         0x1
   struct ifmultiaddr {
           CK_STAILQ_ENTRY(ifmultiaddr) ifma_link; /* queue macro glue */
           struct  sockaddr *ifma_addr;    /* address this membership is for */
           struct  sockaddr *ifma_lladdr;  /* link-layer translation, if any */
           struct  ifnet *ifma_ifp;        /* back-pointer to interface */
           u_int   ifma_refcount;          /* reference count */
           int     ifma_flags;
           void    *ifma_protospec;        /* protocol-specific state, if any */
           struct  ifmultiaddr *ifma_llifma; /* pointer to ifma for ifma_lladdr */
           struct  epoch_context   ifma_epoch_ctx;
   };
   
   extern  struct rwlock ifnet_rwlock;
   extern  struct sx ifnet_sxlock;
   
   #define IFNET_WLOCK() do {                                              \
           sx_xlock(&ifnet_sxlock);                                        \
           rw_wlock(&ifnet_rwlock);                                        \
   } while (0)
   
   #define IFNET_WUNLOCK() do {                                            \
           rw_wunlock(&ifnet_rwlock);                                      \
           sx_xunlock(&ifnet_sxlock);                                      \
   } while (0)
   
   /*
    * To assert the ifnet lock, you must know not only whether it's for read or
    * write, but also whether it was acquired with sleep support or not.
    */
   #define IFNET_RLOCK_ASSERT()            sx_assert(&ifnet_sxlock, SA_SLOCKED)
   #define IFNET_RLOCK_NOSLEEP_ASSERT()    MPASS(in_epoch(net_epoch_preempt))
   #define IFNET_WLOCK_ASSERT() do {                                       \
           sx_assert(&ifnet_sxlock, SA_XLOCKED);                           \
           rw_assert(&ifnet_rwlock, RA_WLOCKED);                           \
   } while (0)
   
   #define IFNET_RLOCK()           sx_slock(&ifnet_sxlock)
   #define IFNET_RLOCK_NOSLEEP()   struct epoch_tracker ifnet_rlock_et; epoch_enter_preempt(net_epoch_preempt, &ifnet_rlock_et)
   #define IFNET_RUNLOCK()         sx_sunlock(&ifnet_sxlock)
   #define IFNET_RUNLOCK_NOSLEEP() epoch_exit_preempt(net_epoch_preempt, &ifnet_rlock_et)
   
   /*
    * Look up an ifnet given its index; the _ref variant also acquires a
    * reference that must be freed using if_rele().  It is almost always a bug
    * to call ifnet_byindex() instead of ifnet_byindex_ref().
    */
   struct ifnet    *ifnet_byindex(u_short idx);
   struct ifnet    *ifnet_byindex_locked(u_short idx);
   struct ifnet    *ifnet_byindex_ref(u_short idx);
   
   /*
    * Given the index, ifaddr_byindex() returns the one and only
    * link-level ifaddr for the interface. You are not supposed to use
    * it to traverse the list of addresses associated to the interface.
    */
   struct ifaddr   *ifaddr_byindex(u_short idx);
   
   VNET_DECLARE(struct ifnethead, ifnet);
   VNET_DECLARE(struct ifgrouphead, ifg_head);
   VNET_DECLARE(int, if_index);
   VNET_DECLARE(struct ifnet *, loif);     /* first loopback interface */
   
   #define V_ifnet         VNET(ifnet)
   #define V_ifg_head      VNET(ifg_head)
   #define V_if_index      VNET(if_index)
   #define V_loif          VNET(loif)
   
   #ifdef MCAST_VERBOSE
   #define MCDPRINTF printf
   #else
   #define MCDPRINTF(...)
   #endif
   
   int     if_addgroup(struct ifnet *, const char *);
   int     if_delgroup(struct ifnet *, const char *);
   int     if_addmulti(struct ifnet *, struct sockaddr *, struct ifmultiaddr **);
   int     if_allmulti(struct ifnet *, int);
   struct  ifnet* if_alloc(u_char);
   void    if_attach(struct ifnet *);
   void    if_dead(struct ifnet *);
   int     if_delmulti(struct ifnet *, struct sockaddr *);
   void    if_delmulti_ifma(struct ifmultiaddr *);
   void    if_delmulti_ifma_flags(struct ifmultiaddr *, int flags);
   void    if_detach(struct ifnet *);
   void    if_purgeaddrs(struct ifnet *);
   void    if_delallmulti(struct ifnet *);
   void    if_down(struct ifnet *);
   struct ifmultiaddr *
           if_findmulti(struct ifnet *, const struct sockaddr *);
   void    if_freemulti(struct ifmultiaddr *ifma);
   void    if_free(struct ifnet *);
   void    if_initname(struct ifnet *, const char *, int);
   void    if_link_state_change(struct ifnet *, int);
   int     if_printf(struct ifnet *, const char *, ...) __printflike(2, 3);
   void    if_ref(struct ifnet *);
   void    if_rele(struct ifnet *);
   int     if_setlladdr(struct ifnet *, const u_char *, int);
   int     if_tunnel_check_nesting(struct ifnet *, struct mbuf *, uint32_t, int);
   void    if_up(struct ifnet *);
   int     ifioctl(struct socket *, u_long, caddr_t, struct thread *);
   int     ifpromisc(struct ifnet *, int);
   struct  ifnet *ifunit(const char *);
   struct  ifnet *ifunit_ref(const char *);
   
   int     ifa_add_loopback_route(struct ifaddr *, struct sockaddr *);
   int     ifa_del_loopback_route(struct ifaddr *, struct sockaddr *);
   int     ifa_switch_loopback_route(struct ifaddr *, struct sockaddr *);
   
   struct  ifaddr *ifa_ifwithaddr(const struct sockaddr *);
   int             ifa_ifwithaddr_check(const struct sockaddr *);
   struct  ifaddr *ifa_ifwithbroadaddr(const struct sockaddr *, int);
   struct  ifaddr *ifa_ifwithdstaddr(const struct sockaddr *, int);
   struct  ifaddr *ifa_ifwithnet(const struct sockaddr *, int, int);
   struct  ifaddr *ifa_ifwithroute(int, const struct sockaddr *, struct sockaddr *,
       u_int);
   struct  ifaddr *ifaof_ifpforaddr(const struct sockaddr *, struct ifnet *);
   int     ifa_preferred(struct ifaddr *, struct ifaddr *);
   
   int     if_simloop(struct ifnet *ifp, struct mbuf *m, int af, int hlen);
   
   typedef void *if_com_alloc_t(u_char type, struct ifnet *ifp);
   typedef void if_com_free_t(void *com, u_char type);
   void    if_register_com_alloc(u_char type, if_com_alloc_t *a, if_com_free_t *f);
   void    if_deregister_com_alloc(u_char type);
   void    if_data_copy(struct ifnet *, struct if_data *);
   uint64_t if_get_counter_default(struct ifnet *, ift_counter);
   void    if_inc_counter(struct ifnet *, ift_counter, int64_t);
   
   #define IF_LLADDR(ifp)                                                  \
       LLADDR((struct sockaddr_dl *)((ifp)->if_addr->ifa_addr))
   
   uint64_t if_setbaudrate(if_t ifp, uint64_t baudrate);
   uint64_t if_getbaudrate(if_t ifp);
   int if_setcapabilities(if_t ifp, int capabilities);
   int if_setcapabilitiesbit(if_t ifp, int setbit, int clearbit);
   int if_getcapabilities(if_t ifp);
   int if_togglecapenable(if_t ifp, int togglecap);
   int if_setcapenable(if_t ifp, int capenable);
   int if_setcapenablebit(if_t ifp, int setcap, int clearcap);
   int if_getcapenable(if_t ifp);
   const char *if_getdname(if_t ifp);
   int if_setdev(if_t ifp, void *dev);
   int if_setdrvflagbits(if_t ifp, int if_setflags, int clear_flags);
   int if_getdrvflags(if_t ifp);
   int if_setdrvflags(if_t ifp, int flags);
   int if_clearhwassist(if_t ifp);
   int if_sethwassistbits(if_t ifp, int toset, int toclear);
   int if_sethwassist(if_t ifp, int hwassist_bit);
   int if_gethwassist(if_t ifp);
   int if_setsoftc(if_t ifp, void *softc);
   void *if_getsoftc(if_t ifp);
   int if_setflags(if_t ifp, int flags);
   int if_gethwaddr(if_t ifp, struct ifreq *);
   int if_setmtu(if_t ifp, int mtu);
   int if_getmtu(if_t ifp);
   int if_getmtu_family(if_t ifp, int family);
   int if_setflagbits(if_t ifp, int set, int clear);
   int if_getflags(if_t ifp);
   int if_sendq_empty(if_t ifp);
   int if_setsendqready(if_t ifp);
   int if_setsendqlen(if_t ifp, int tx_desc_count);
   int if_sethwtsomax(if_t ifp, u_int if_hw_tsomax);
   int if_sethwtsomaxsegcount(if_t ifp, u_int if_hw_tsomaxsegcount);
   int if_sethwtsomaxsegsize(if_t ifp, u_int if_hw_tsomaxsegsize);
   u_int if_gethwtsomax(if_t ifp);
   u_int if_gethwtsomaxsegcount(if_t ifp);
   u_int if_gethwtsomaxsegsize(if_t ifp);
   int if_input(if_t ifp, struct mbuf* sendmp);
   int if_sendq_prepend(if_t ifp, struct mbuf *m);
   struct mbuf *if_dequeue(if_t ifp);
   int if_setifheaderlen(if_t ifp, int len);
   void if_setrcvif(struct mbuf *m, if_t ifp);
   void if_setvtag(struct mbuf *m, u_int16_t tag);
   u_int16_t if_getvtag(struct mbuf *m);
   int if_vlantrunkinuse(if_t ifp);
   caddr_t if_getlladdr(if_t ifp);
   void *if_gethandle(u_char);
   void if_bpfmtap(if_t ifp, struct mbuf *m);
   void if_etherbpfmtap(if_t ifp, struct mbuf *m);
   void if_vlancap(if_t ifp);
   
   int if_setupmultiaddr(if_t ifp, void *mta, int *cnt, int max);
   int if_multiaddr_array(if_t ifp, void *mta, int *cnt, int max);
   int if_multiaddr_count(if_t ifp, int max);
   
   int if_multi_apply(struct ifnet *ifp, int (*filter)(void *, struct ifmultiaddr *, int), void *arg);
   int if_getamcount(if_t ifp);
   struct ifaddr * if_getifaddr(if_t ifp);
   
   /* Functions */
   void if_setinitfn(if_t ifp, void (*)(void *));
   void if_setioctlfn(if_t ifp, int (*)(if_t, u_long, caddr_t));
   void if_setstartfn(if_t ifp, void (*)(if_t));
   void if_settransmitfn(if_t ifp, if_transmit_fn_t);
   void if_setqflushfn(if_t ifp, if_qflush_fn_t);
   void if_setgetcounterfn(if_t ifp, if_get_counter_t);
    
   /* Revisit the below. These are inline functions originally */
   int drbr_inuse_drv(if_t ifp, struct buf_ring *br);
   struct mbuf* drbr_dequeue_drv(if_t ifp, struct buf_ring *br);
   int drbr_needs_enqueue_drv(if_t ifp, struct buf_ring *br);
   int drbr_enqueue_drv(if_t ifp, struct buf_ring *br, struct mbuf *m);
   
   /* TSO */
   void if_hw_tsomax_common(if_t ifp, struct ifnet_hw_tsomax *);
   int if_hw_tsomax_update(if_t ifp, struct ifnet_hw_tsomax *);
   
   /* accessors for struct ifreq */
   void *ifr_data_get_ptr(void *ifrp);
   
   int ifhwioctl(u_long, struct ifnet *, caddr_t, struct thread *);
   
   #ifdef DEVICE_POLLING
   enum poll_cmd { POLL_ONLY, POLL_AND_CHECK_STATUS };
   
   typedef int poll_handler_t(if_t ifp, enum poll_cmd cmd, int count);
   int    ether_poll_register(poll_handler_t *h, if_t ifp);
   int    ether_poll_deregister(if_t ifp);
   #endif /* DEVICE_POLLING */
   
   #endif /* _KERNEL */
   
   #include <net/ifq.h>    /* XXXAO: temporary unconditional include */
   
   #endif /* !_NET_IF_VAR_H_ */

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