FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_accf.c

     /*
      * Copyright (c) 2000 Paycounter, Inc.
      * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
      * 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.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
     *
     *      $FreeBSD: src/sys/kern/uipc_accf.c,v 1.2.2.2 2000/09/20 21:19:21 ps Exp $
     */
    
    #define ACCEPT_FILTER_MOD
    
    #include "opt_param.h"
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/domain.h>
    #include <sys/kernel.h>
    #include <sys/proc.h>
    #include <sys/malloc.h>
    #include <sys/mbuf.h>
    #include <sys/protosw.h>
    #include <sys/sysctl.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h>
    #include <sys/queue.h>
    #include <sys/thread2.h>
    
    static SLIST_HEAD(, accept_filter) accept_filtlsthd =
            SLIST_HEAD_INITIALIZER(&accept_filtlsthd);
    
    MALLOC_DEFINE(M_ACCF, "accf", "accept filter data");
    
    static int unloadable = 0;
    
    SYSCTL_DECL(_net_inet); /* XXX: some header should do this for me */
    SYSCTL_NODE(_net_inet, OID_AUTO, accf, CTLFLAG_RW, 0, "Accept filters");
    SYSCTL_INT(_net_inet_accf, OID_AUTO, unloadable, CTLFLAG_RW, &unloadable, 0,
            "Allow unload of accept filters (not recommended)");
    
    /*
     * must be passed a malloc'd structure so we don't explode if the kld
     * is unloaded, we leak the struct on deallocation to deal with this,
     * but if a filter is loaded with the same name as a leaked one we re-use
     * the entry.
     */
    int
    accept_filt_add(struct accept_filter *filt)
    {
            struct accept_filter *p;
    
            SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
                    if (strcmp(p->accf_name, filt->accf_name) == 0)  {
                            if (p->accf_callback != NULL) {
                                    return (EEXIST);
                            } else {
                                    p->accf_callback = filt->accf_callback;
                                    kfree(filt, M_ACCF);
                                    return (0);
                            }
                    }
                                    
            if (p == NULL)
                    SLIST_INSERT_HEAD(&accept_filtlsthd, filt, accf_next);
            return (0);
    }
    
    int
    accept_filt_del(char *name)
    {
            struct accept_filter *p;
    
            p = accept_filt_get(name);
            if (p == NULL)
                    return (ENOENT);
    
            p->accf_callback = NULL;
            return (0);
    }
    
    struct accept_filter *
   accept_filt_get(char *name)
   {
           struct accept_filter *p;
   
           SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
                   if (strcmp(p->accf_name, name) == 0)
                           return (p);
   
           return (NULL);
   }
   
   int
   accept_filt_generic_mod_event(module_t mod, int event, void *data)
   {
           struct accept_filter *p;
           struct accept_filter *accfp = (struct accept_filter *) data;
           int     error;
   
           switch (event) {
           case MOD_LOAD:
                   p = kmalloc(sizeof(*p), M_ACCF, M_WAITOK);
                   bcopy(accfp, p, sizeof(*p));
                   crit_enter();
                   error = accept_filt_add(p);
                   crit_exit();
                   break;
   
           case MOD_UNLOAD:
                   /*
                    * Do not support unloading yet. we don't keep track of refcounts
                    * and unloading an accept filter callback and then having it called
                    * is a bad thing.  A simple fix would be to track the refcount
                    * in the struct accept_filter.
                    */
                   if (unloadable != 0) {
                           crit_enter();
                           error = accept_filt_del(accfp->accf_name);
                           crit_exit();
                   } else
                           error = EOPNOTSUPP;
                   break;
   
           case MOD_SHUTDOWN:
                   error = 0;
                   break;
   
           default:
                   error = EOPNOTSUPP;
                   break;
           }
   
           return (error);
   }

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