FreeBSD/Linux Kernel Cross Reference
sys/net/pfil.c

     /*      $FreeBSD: releng/5.1/sys/net/pfil.c 111119 2003-02-19 05:47:46Z imp $   */
     
     /*
      * Copyright (c) 1996 Matthew R. Green
      * 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. The name of the author may not be used to endorse or promote products
     *    derived from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
     */
    
    #include <sys/param.h>
    #include <sys/errno.h>
    #include <sys/malloc.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h>
    #include <sys/systm.h>
    #include <sys/queue.h>
    
    #include <net/if.h>
    #include <net/pfil.h>
    
    static void pfil_init(struct pfil_head *);
    static int pfil_list_add(pfil_list_t *,
        int (*)(void *, int, struct ifnet *, int, struct mbuf **), int);
    static int pfil_list_remove(pfil_list_t *,
        int (*)(void *, int, struct ifnet *, int, struct mbuf **));
    
    static void
    pfil_init(ph)
             struct pfil_head *ph;
    {
    
            TAILQ_INIT(&ph->ph_in);
            TAILQ_INIT(&ph->ph_out);
            ph->ph_init = 1;
    }
    
    /*
     * pfil_add_hook() adds a function to the packet filter hook.  the
     * flags are:
     *      PFIL_IN         call me on incoming packets
     *      PFIL_OUT        call me on outgoing packets
     *      PFIL_ALL        call me on all of the above
     *      PFIL_WAITOK     OK to call malloc with M_WAITOK.
     */
    int
    pfil_add_hook(func, flags, ph)
            int     (*func)(void *, int, struct ifnet *, int, struct mbuf **);
            int     flags;
            struct  pfil_head       *ph;
    {
            int err = 0;
    
            if (ph->ph_init == 0)
                    pfil_init(ph);
    
            if (flags & PFIL_IN)
                    err = pfil_list_add(&ph->ph_in, func, flags & ~PFIL_OUT);
            if (err)
                    return err;
            if (flags & PFIL_OUT)
                    err = pfil_list_add(&ph->ph_out, func, flags & ~PFIL_IN);
            if (err) {
                    if (flags & PFIL_IN)
                            pfil_list_remove(&ph->ph_in, func);
                    return err;
            }
            return 0;
    }
    
    static int
    pfil_list_add(list, func, flags)
            pfil_list_t *list;
            int     (*func)(void *, int, struct ifnet *, int, struct mbuf **);
            int flags;
    {
            struct packet_filter_hook *pfh;
    
            pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR,
               flags & PFIL_WAITOK ? M_WAITOK : M_NOWAIT);
           if (pfh == NULL)
                   return ENOMEM;
           pfh->pfil_func = func;
           /*
            * insert the input list in reverse order of the output list
            * so that the same path is followed in or out of the kernel.
            */
           
           if (flags & PFIL_IN)
                   TAILQ_INSERT_HEAD(list, pfh, pfil_link);
           else
                   TAILQ_INSERT_TAIL(list, pfh, pfil_link);
           return 0;
   }
   
   /*
    * pfil_remove_hook removes a specific function from the packet filter
    * hook list.
    */
   int
   pfil_remove_hook(func, flags, ph)
           int     (*func)(void *, int, struct ifnet *, int, struct mbuf **);
           int     flags;
           struct  pfil_head       *ph;
   {
           int err = 0;
   
           if (ph->ph_init == 0)
                   pfil_init(ph);
   
           if (flags & PFIL_IN)
                   err = pfil_list_remove(&ph->ph_in, func);
           if ((err == 0) && (flags & PFIL_OUT))
                   err = pfil_list_remove(&ph->ph_out, func);
           return err;
   }
   
   /*
    * pfil_list_remove is an internal function that takes a function off the
    * specified list.
    */
   static int
   pfil_list_remove(list, func)
           pfil_list_t *list;
           int     (*func)(void *, int, struct ifnet *, int, struct mbuf **);
   {
           struct packet_filter_hook *pfh;
   
           TAILQ_FOREACH(pfh, list, pfil_link)
                   if (pfh->pfil_func == func) {
                           TAILQ_REMOVE(list, pfh, pfil_link);
                           free(pfh, M_IFADDR);
                           return 0;
                   }
           return ENOENT;
   }
   
   struct packet_filter_hook *
   pfil_hook_get(flag, ph)
           int flag;
           struct  pfil_head       *ph;
   {
           if (ph->ph_init != 0)
                   switch (flag) {
                   case PFIL_IN:
                           return (TAILQ_FIRST(&ph->ph_in));
                   case PFIL_OUT:
                           return (TAILQ_FIRST(&ph->ph_out));
                   }
           return NULL;
   }

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