FreeBSD/Linux Kernel Cross Reference
sys/netinet/in_hostcache.c

     /*
      * Copyright 1997 Massachusetts Institute of Technology
      *
      * Permission to use, copy, modify, and distribute this software and
      * its documentation for any purpose and without fee is hereby
      * granted, provided that both the above copyright notice and this
      * permission notice appear in all copies, that both the above
      * copyright notice and this permission notice appear in all
      * supporting documentation, and that the name of M.I.T. not be used
     * in advertising or publicity pertaining to distribution of the
     * software without specific, written prior permission.  M.I.T. makes
     * no representations about the suitability of this software for any
     * purpose.  It is provided "as is" without express or implied
     * warranty.
     * 
     * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
     * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
     * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
     * SHALL M.I.T. 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.
     *
     * $FreeBSD$
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/malloc.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h>
    
    #include <net/hostcache.h>
    #include <net/if.h>
    #include <net/if_var.h>
    #include <net/route.h>
    
    #include <netinet/in.h>
    #include <netinet/in_hostcache.h>
    #include <netinet/tcp.h>
    #include <netinet/tcp_timer.h>
    #include <netinet/tcp_var.h>
    
    /*
     * Manage the IP per-host cache (really a thin veneer over the generic
     * per-host cache code).
     */
    
    /* Look up an entry -- can be called from interrupt context. */
    struct in_hcentry *
    inhc_lookup(struct sockaddr_in *sin)
    {
            struct hcentry *hc;
    
            hc = hc_get((struct sockaddr *)sin);
            return ((struct in_hcentry *)hc);
    }
    
    /* Look up and possibly create an entry -- must be called from user mode. */
    struct in_hcentry *
    inhc_alloc(struct sockaddr_in *sin)
    {
            struct in_hcentry *inhc;
            struct rtentry *rt;
            int error;
            /* xxx mutual exclusion for smp */
    
            inhc = inhc_lookup(sin);
            if (inhc != 0)
                    return inhc;
    
            rt = rtalloc1(inhc->inhc_hc.hc_host, 1, 0);
            if (rt == 0)
                    return 0;
    
            MALLOC(inhc, struct in_hcentry *, sizeof *inhc, M_HOSTCACHE, M_WAITOK);
            bzero(inhc, sizeof *inhc);
            inhc->inhc_hc.hc_host = dup_sockaddr((struct sockaddr *)sin, 1);
            if (in_broadcast(sin->sin_addr, rt->rt_ifp))
                    inhc->inhc_flags |= INHC_BROADCAST;
            else if (((struct sockaddr_in *)rt->rt_ifa->ifa_addr)->sin_addr.s_addr
                    == sin->sin_addr.s_addr)
                    inhc->inhc_flags |= INHC_LOCAL;
            else if (IN_MULTICAST(ntohl(sin->sin_addr.s_addr)))
                    inhc->inhc_flags |= INHC_MULTICAST;
            inhc->inhc_pmtu = rt->rt_rmx.rmx_mtu;
            inhc->inhc_recvpipe = rt->rt_rmx.rmx_recvpipe;
            inhc->inhc_sendpipe = rt->rt_rmx.rmx_sendpipe;
            inhc->inhc_ssthresh = rt->rt_rmx.rmx_ssthresh;
            if (rt->rt_rmx.rmx_locks & RTV_RTT)
                    inhc->inhc_rttmin = rt->rt_rmx.rmx_rtt
                            / (RTM_RTTUNIT / TCP_RTT_SCALE);
            inhc->inhc_hc.hc_rt = rt;
            error = hc_insert(&inhc->inhc_hc);
           if (error != 0) {
                   RTFREE(rt);
                   FREE(inhc, M_HOSTCACHE);
                   return 0;
           }
           /*
            * We don't return the structure directly because hc_get() needs
            * to be allowed to do its own processing.
            */
           return (inhc_lookup(sin));
   }
   
   /*
    * This is Van Jacobson's hash function for IPv4 addresses.
    * It is designed to work with a power-of-two-sized hash table.
    */
   static u_long
   inhc_hash(struct sockaddr *sa, u_long nbuckets)
   {
           u_long ip;
   
           ip = ((struct sockaddr_in *)sa)->sin_addr.s_addr;
           return ((ip ^ (ip >> 23) ^ (ip >> 17)) & ~(nbuckets - 1));
   }
   
   /*
    * We don't need to do any special work... if there are no references,
    * as the caller has already ensured, then it's OK to kill.
    */
   static int
   inhc_delete(struct hcentry *hc)
   {
           return 0;
   }
   
   /*
    * Return the next increment for the number of buckets in the hash table.
    * Zero means ``do not bump''.
    */
   static u_long
   inhc_bump(u_long oldsize)
   {
           if (oldsize < 512)
                   return (oldsize << 1);
           return 0;
   }
   
   static struct hccallback inhc_cb = {
           inhc_hash, inhc_delete, inhc_bump
   };
   
   int
   inhc_init(void)
   {
   
           return (hc_init(AF_INET, &inhc_cb, 128, 0));
   }
   

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