425 lines
10 KiB
C
425 lines
10 KiB
C
/* $NetBSD: ip_flow.c,v 1.23 2002/03/08 20:48:43 thorpej Exp $ */
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/*-
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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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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: ip_flow.c,v 1.23 2002/03/08 20:48:43 thorpej Exp $");
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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/domain.h>
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#include <sys/protosw.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/errno.h>
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#include <sys/time.h>
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#include <sys/kernel.h>
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#include <sys/pool.h>
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#include <sys/sysctl.h>
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#include <net/if.h>
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#include <net/if_dl.h>
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#include <net/route.h>
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#include <net/pfil.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_pcb.h>
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#include <netinet/in_var.h>
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#include <netinet/ip_var.h>
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struct pool ipflow_pool;
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LIST_HEAD(ipflowhead, ipflow);
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#define IPFLOW_TIMER (5 * PR_SLOWHZ)
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#define IPFLOW_HASHSIZE (1 << IPFLOW_HASHBITS)
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static struct ipflowhead ipflowtable[IPFLOW_HASHSIZE];
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static struct ipflowhead ipflowlist;
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static int ipflow_inuse;
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#define IPFLOW_INSERT(bucket, ipf) \
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do { \
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LIST_INSERT_HEAD((bucket), (ipf), ipf_hash); \
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LIST_INSERT_HEAD(&ipflowlist, (ipf), ipf_list); \
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} while (0)
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#define IPFLOW_REMOVE(ipf) \
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do { \
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LIST_REMOVE((ipf), ipf_hash); \
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LIST_REMOVE((ipf), ipf_list); \
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} while (0)
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#ifndef IPFLOW_MAX
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#define IPFLOW_MAX 256
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#endif
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int ip_maxflows = IPFLOW_MAX;
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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(&ipflowtable[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_hash);
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}
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return ipf;
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}
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void
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ipflow_init()
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{
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int i;
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pool_init(&ipflow_pool, sizeof(struct ipflow), 0, 0, 0, "ipflowpl",
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NULL);
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LIST_INIT(&ipflowlist);
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for (i = 0; i < IPFLOW_HASHSIZE; i++)
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LIST_INIT(&ipflowtable[i]);
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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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struct sockaddr *dst;
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int error;
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int iplen;
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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_inuse == 0 || m->m_len < sizeof(struct ip))
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return 0;
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/*
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* Was packet received as a link-level multicast or broadcast?
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* If so, don't try to fast forward..
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*/
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if ((m->m_flags & (M_BCAST|M_MCAST)) != 0)
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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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iplen = ntohs(ip->ip_len);
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if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) ||
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iplen < sizeof(struct ip) || iplen > 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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* Verify the IP header checksum.
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*/
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switch (m->m_pkthdr.csum_flags &
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((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_IPv4) |
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M_CSUM_IPv4_BAD)) {
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case M_CSUM_IPv4|M_CSUM_IPv4_BAD:
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return (0);
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case M_CSUM_IPv4:
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/* Checksum was okay. */
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break;
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default:
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/* Must compute it ourselves. */
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if (in_cksum(m, sizeof(struct ip)) != 0)
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return (0);
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break;
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}
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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 ||
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(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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* Clear any in-bound checksum flags for this packet.
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*/
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m->m_pkthdr.csum_flags = 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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* This method of adding the checksum works on either endian CPU.
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* If htons() is inlined, all the arithmetic is folded; otherwise
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* the htons()s are combined by CSE due to the __const__ attribute.
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*
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* Don't bother using HW checksumming here -- the incremental
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* update is pretty fast.
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*/
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ip->ip_ttl -= IPTTLDEC;
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if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8))
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ip->ip_sum -= ~htons(IPTTLDEC << 8);
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else
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ip->ip_sum += htons(IPTTLDEC << 8);
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/*
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* Trim the packet in case it's too long..
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*/
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if (m->m_pkthdr.len > iplen) {
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if (m->m_len == m->m_pkthdr.len) {
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m->m_len = iplen;
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m->m_pkthdr.len = iplen;
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} else
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m_adj(m, iplen - m->m_pkthdr.len);
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}
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/*
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* Send the packet on it's way. All we can get back is ENOBUFS
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*/
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ipf->ipf_uses++;
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PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
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if (rt->rt_flags & RTF_GATEWAY)
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dst = rt->rt_gateway;
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else
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dst = &ipf->ipf_ro.ro_dst;
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if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 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 = splnet();
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IPFLOW_REMOVE(ipf);
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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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pool_put(&ipflow_pool, ipf);
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}
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struct ipflow *
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ipflow_reap(
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int just_one)
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{
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while (just_one || ipflow_inuse > ip_maxflows) {
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struct ipflow *ipf, *maybe_ipf = NULL;
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int s;
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ipf = LIST_FIRST(&ipflowlist);
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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
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* used or has had the least uses in the
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* last 1.5 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_list);
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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 = splnet();
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IPFLOW_REMOVE(ipf);
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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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if (just_one)
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return ipf;
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pool_put(&ipflow_pool, ipf);
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ipflow_inuse--;
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}
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return NULL;
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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, *next_ipf;
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ipf = LIST_FIRST(&ipflowlist);
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while (ipf != NULL) {
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next_ipf = LIST_NEXT(ipf, ipf_list);
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if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer)) {
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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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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 (ip_maxflows == 0 || 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 >= ip_maxflows) {
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ipf = ipflow_reap(1);
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} else {
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ipf = pool_get(&ipflow_pool, PR_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 = splnet();
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IPFLOW_REMOVE(ipf);
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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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PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
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ipf->ipf_start = time.tv_sec;
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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 = splnet();
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IPFLOW_INSERT(&ipflowtable[hash], ipf);
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splx(s);
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}
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