328 lines
8.3 KiB
C
328 lines
8.3 KiB
C
/*-
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* Copyright (c) 1998 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by the 3am Software Foundry ("3am"). It was developed by Matt Thomas.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/protosw.h>
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#include <sys/socket.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <net/if.h>
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#include <net/route.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/in_var.h>
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#include <netinet/ip_var.h>
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#include <netinet/ip_flow.h>
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#define IPFLOW_TIMER (5 * PR_SLOWHZ)
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#define IPFLOW_HASHBITS 6 /* should not be a multiple of 8 */
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#define IPFLOW_HASHSIZE (1 << IPFLOW_HASHBITS)
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static LIST_HEAD(ipflowhead, ipflow) ipflows[IPFLOW_HASHSIZE];
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static int ipflow_inuse;
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#define IPFLOW_MAX 256
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static int ipflow_active = 0;
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SYSCTL_INT(_net_inet_ip, IPCTL_FASTFORWARDING, fastforwarding, CTLFLAG_RW,
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&ipflow_active, 0, "Enable flow-based IP forwarding");
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static MALLOC_DEFINE(M_IPFLOW, "ip_flow", "IP flow");
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static unsigned
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ipflow_hash(
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struct in_addr dst,
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struct in_addr src,
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unsigned tos)
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{
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unsigned hash = tos;
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int idx;
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for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS)
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hash += (dst.s_addr >> (32 - idx)) + (src.s_addr >> idx);
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return hash & (IPFLOW_HASHSIZE-1);
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}
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static struct ipflow *
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ipflow_lookup(
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const struct ip *ip)
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{
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unsigned hash;
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struct ipflow *ipf;
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hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos);
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ipf = LIST_FIRST(&ipflows[hash]);
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while (ipf != NULL) {
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if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr
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&& ip->ip_src.s_addr == ipf->ipf_src.s_addr
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&& ip->ip_tos == ipf->ipf_tos)
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break;
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ipf = LIST_NEXT(ipf, ipf_next);
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}
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return ipf;
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}
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int
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ipflow_fastforward(
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struct mbuf *m)
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{
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struct ip *ip;
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struct ipflow *ipf;
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struct rtentry *rt;
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int error;
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/*
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* Are we forwarding packets? Big enough for an IP packet?
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*/
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if (!ipforwarding || !ipflow_active || m->m_len < sizeof(struct ip))
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return 0;
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/*
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* IP header with no option and valid version and length
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*/
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ip = mtod(m, struct ip *);
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if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2)
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|| ntohs(ip->ip_len) > m->m_pkthdr.len)
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return 0;
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/*
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* Find a flow.
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*/
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if ((ipf = ipflow_lookup(ip)) == NULL)
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return 0;
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/*
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* Route and interface still up?
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*/
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rt = ipf->ipf_ro.ro_rt;
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if ((rt->rt_flags & RTF_UP) == 0 || (rt->rt_ifp->if_flags & IFF_UP) == 0)
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return 0;
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/*
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* Packet size OK? TTL?
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*/
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if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC)
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return 0;
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/*
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* Everything checks out and so we can forward this packet.
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* Modify the TTL and incrementally change the checksum.
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*/
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ip->ip_ttl -= IPTTLDEC;
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if (ip->ip_sum >= htons(0xffff - (IPTTLDEC << 8))) {
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ip->ip_sum += htons(IPTTLDEC << 8) + 1;
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} else {
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ip->ip_sum += htons(IPTTLDEC << 8);
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}
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/*
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* Send the packet on its way. All we can get back is ENOBUFS
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*/
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ipf->ipf_uses++;
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ipf->ipf_timer = IPFLOW_TIMER;
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if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, &ipf->ipf_ro.ro_dst, rt)) != 0) {
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if (error == ENOBUFS)
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ipf->ipf_dropped++;
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else
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ipf->ipf_errors++;
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}
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return 1;
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}
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static void
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ipflow_addstats(
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struct ipflow *ipf)
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{
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ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses;
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ipstat.ips_cantforward += ipf->ipf_errors + ipf->ipf_dropped;
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ipstat.ips_forward += ipf->ipf_uses;
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ipstat.ips_fastforward += ipf->ipf_uses;
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}
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static void
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ipflow_free(
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struct ipflow *ipf)
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{
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int s;
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/*
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* Remove the flow from the hash table (at elevated IPL).
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* Once it's off the list, we can deal with it at normal
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* network IPL.
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*/
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s = splimp();
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LIST_REMOVE(ipf, ipf_next);
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splx(s);
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ipflow_addstats(ipf);
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RTFREE(ipf->ipf_ro.ro_rt);
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ipflow_inuse--;
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FREE(ipf, M_IPFLOW);
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}
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static struct ipflow *
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ipflow_reap(
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void)
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{
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struct ipflow *ipf, *maybe_ipf = NULL;
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int idx;
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int s;
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for (idx = 0; idx < IPFLOW_HASHSIZE; idx++) {
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ipf = LIST_FIRST(&ipflows[idx]);
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while (ipf != NULL) {
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/*
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* If this no longer points to a valid route
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* reclaim it.
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*/
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if ((ipf->ipf_ro.ro_rt->rt_flags & RTF_UP) == 0)
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goto done;
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/*
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* choose the one that's been least recently used
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* or has had the least uses in the last 1.5
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* intervals.
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*/
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if (maybe_ipf == NULL
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|| ipf->ipf_timer < maybe_ipf->ipf_timer
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|| (ipf->ipf_timer == maybe_ipf->ipf_timer
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&& ipf->ipf_last_uses + ipf->ipf_uses <
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maybe_ipf->ipf_last_uses +
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maybe_ipf->ipf_uses))
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maybe_ipf = ipf;
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ipf = LIST_NEXT(ipf, ipf_next);
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}
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}
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ipf = maybe_ipf;
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done:
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/*
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* Remove the entry from the flow table.
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*/
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s = splimp();
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LIST_REMOVE(ipf, ipf_next);
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splx(s);
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ipflow_addstats(ipf);
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RTFREE(ipf->ipf_ro.ro_rt);
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return ipf;
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}
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void
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ipflow_slowtimo(
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void)
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{
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struct ipflow *ipf;
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int idx;
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for (idx = 0; idx < IPFLOW_HASHSIZE; idx++) {
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ipf = LIST_FIRST(&ipflows[idx]);
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while (ipf != NULL) {
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struct ipflow *next_ipf = LIST_NEXT(ipf, ipf_next);
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if (--ipf->ipf_timer == 0) {
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ipflow_free(ipf);
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} else {
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ipf->ipf_last_uses = ipf->ipf_uses;
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ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses;
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ipstat.ips_forward += ipf->ipf_uses;
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ipstat.ips_fastforward += ipf->ipf_uses;
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ipf->ipf_uses = 0;
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}
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ipf = next_ipf;
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}
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}
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}
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void
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ipflow_create(
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const struct route *ro,
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struct mbuf *m)
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{
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const struct ip *const ip = mtod(m, struct ip *);
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struct ipflow *ipf;
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unsigned hash;
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int s;
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/*
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* Don't create cache entries for ICMP messages.
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*/
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if (!ipflow_active || ip->ip_p == IPPROTO_ICMP)
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return;
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/*
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* See if an existing flow struct exists. If so remove it from it's
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* list and free the old route. If not, try to malloc a new one
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* (if we aren't at our limit).
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*/
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ipf = ipflow_lookup(ip);
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if (ipf == NULL) {
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if (ipflow_inuse == IPFLOW_MAX) {
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ipf = ipflow_reap();
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} else {
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ipf = (struct ipflow *) malloc(sizeof(*ipf), M_IPFLOW,
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M_NOWAIT);
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if (ipf == NULL)
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return;
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ipflow_inuse++;
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}
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bzero((caddr_t) ipf, sizeof(*ipf));
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} else {
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s = splimp();
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LIST_REMOVE(ipf, ipf_next);
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splx(s);
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ipflow_addstats(ipf);
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RTFREE(ipf->ipf_ro.ro_rt);
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ipf->ipf_uses = ipf->ipf_last_uses = 0;
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ipf->ipf_errors = ipf->ipf_dropped = 0;
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}
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/*
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* Fill in the updated information.
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*/
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ipf->ipf_ro = *ro;
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ro->ro_rt->rt_refcnt++;
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ipf->ipf_dst = ip->ip_dst;
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ipf->ipf_src = ip->ip_src;
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ipf->ipf_tos = ip->ip_tos;
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ipf->ipf_timer = IPFLOW_TIMER;
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/*
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* Insert into the approriate bucket of the flow table.
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*/
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hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos);
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s = splimp();
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LIST_INSERT_HEAD(&ipflows[hash], ipf, ipf_next);
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splx(s);
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}
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