Home | History | Annotate | Line # | Download | only in netinet
ip_flow.c revision 1.9 
      1 /*	$NetBSD: ip_flow.c,v 1.9 1999/01/24 13:34:35 mycroft Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1998 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by the 3am Software Foundry ("3am").  It was developed by Matt Thomas.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the NetBSD
     21  *	Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/param.h>
     40 #include <sys/systm.h>
     41 #include <sys/malloc.h>
     42 #include <sys/mbuf.h>
     43 #include <sys/domain.h>
     44 #include <sys/protosw.h>
     45 #include <sys/socket.h>
     46 #include <sys/socketvar.h>
     47 #include <sys/errno.h>
     48 #include <sys/time.h>
     49 #include <sys/kernel.h>
     50 #include <sys/proc.h>
     51 #include <sys/pool.h>
     52 
     53 #include <vm/vm.h>
     54 #include <sys/sysctl.h>
     55 
     56 #include <net/if.h>
     57 #include <net/if_dl.h>
     58 #include <net/route.h>
     59 #include <net/pfil.h>
     60 
     61 #include <netinet/in.h>
     62 #include <netinet/in_systm.h>
     63 #include <netinet/ip.h>
     64 #include <netinet/in_pcb.h>
     65 #include <netinet/in_var.h>
     66 #include <netinet/ip_var.h>
     67 
     68 struct pool ipflow_pool;
     69 
     70 LIST_HEAD(ipflowhead, ipflow);
     71 
     72 #define	IPFLOW_TIMER		(5 * PR_SLOWHZ)
     73 #define	IPFLOW_HASHSIZE		(1 << IPFLOW_HASHBITS)
     74 
     75 static struct ipflowhead ipflowtable[IPFLOW_HASHSIZE];
     76 static struct ipflowhead ipflowlist;
     77 static int ipflow_inuse;
     78 
     79 #define	IPFLOW_INSERT(bucket, ipf) \
     80 do { \
     81 	LIST_INSERT_HEAD((bucket), (ipf), ipf_hash); \
     82 	LIST_INSERT_HEAD(&ipflowlist, (ipf), ipf_list); \
     83 } while (0)
     84 
     85 #define	IPFLOW_REMOVE(ipf) \
     86 do { \
     87 	LIST_REMOVE((ipf), ipf_hash); \
     88 	LIST_REMOVE((ipf), ipf_list); \
     89 } while (0)
     90 
     91 #ifndef IPFLOW_MAX
     92 #define	IPFLOW_MAX		256
     93 #endif
     94 int ip_maxflows = IPFLOW_MAX;
     95 
     96 static unsigned
     97 ipflow_hash(
     98 	struct in_addr dst,
     99 	struct in_addr src,
    100 	unsigned tos)
    101 {
    102 	unsigned hash = tos;
    103 	int idx;
    104 	for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS)
    105 		hash += (dst.s_addr >> (32 - idx)) + (src.s_addr >> idx);
    106 	return hash & (IPFLOW_HASHSIZE-1);
    107 }
    108 
    109 static struct ipflow *
    110 ipflow_lookup(
    111 	const struct ip *ip)
    112 {
    113 	unsigned hash;
    114 	struct ipflow *ipf;
    115 
    116 	hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos);
    117 
    118 	ipf = LIST_FIRST(&ipflowtable[hash]);
    119 	while (ipf != NULL) {
    120 		if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr
    121 		    && ip->ip_src.s_addr == ipf->ipf_src.s_addr
    122 		    && ip->ip_tos == ipf->ipf_tos)
    123 			break;
    124 		ipf = LIST_NEXT(ipf, ipf_hash);
    125 	}
    126 	return ipf;
    127 }
    128 
    129 void
    130 ipflow_init()
    131 {
    132 	int i;
    133 
    134 	pool_init(&ipflow_pool, sizeof(struct ipflow), 0, 0, 0, "ipflowpl",
    135 	    0, NULL, NULL, M_IPFLOW);
    136 
    137 	LIST_INIT(&ipflowlist);
    138 	for (i = 0; i < IPFLOW_HASHSIZE; i++)
    139 		LIST_INIT(&ipflowtable[i]);
    140 }
    141 
    142 int
    143 ipflow_fastforward(
    144 	struct mbuf *m)
    145 {
    146 	struct ip *ip;
    147 	struct ipflow *ipf;
    148 	struct rtentry *rt;
    149 	int error;
    150 	int iplen;
    151 
    152 	/*
    153 	 * Are we forwarding packets?  Big enough for an IP packet?
    154 	 */
    155 	if (!ipforwarding || ipflow_inuse == 0 || m->m_len < sizeof(struct ip))
    156 		return 0;
    157 	/*
    158 	 * IP header with no option and valid version and length
    159 	 */
    160 	ip = mtod(m, struct ip *);
    161 	iplen = ntohs(ip->ip_len);
    162 	if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) ||
    163 	    iplen > m->m_pkthdr.len)
    164 		return 0;
    165 	/*
    166 	 * Find a flow.
    167 	 */
    168 	if ((ipf = ipflow_lookup(ip)) == NULL)
    169 		return 0;
    170 
    171 	/*
    172 	 * Veryify the IP header checksum.
    173 	 */
    174 	if (in_cksum(m, sizeof(struct ip)) != 0)
    175 		return 0;
    176 
    177 	/*
    178 	 * Route and interface still up?
    179 	 */
    180 	rt = ipf->ipf_ro.ro_rt;
    181 	if ((rt->rt_flags & RTF_UP) == 0 ||
    182 	    (rt->rt_ifp->if_flags & IFF_UP) == 0)
    183 		return 0;
    184 
    185 	/*
    186 	 * Packet size OK?  TTL?
    187 	 */
    188 	if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC)
    189 		return 0;
    190 
    191 	/*
    192 	 * Everything checks out and so we can forward this packet.
    193 	 * Modify the TTL and incrementally change the checksum.
    194 	 *
    195 	 * This method of adding the checksum works on either endian CPU.
    196 	 * If htons() is inlined, all the arithmetic is folded; otherwise
    197 	 * the htons()s are combined by CSE due to the __const__ attribute.
    198 	 */
    199 	ip->ip_ttl -= IPTTLDEC;
    200 	if (ip->ip_sum >= 0xffff - htons(IPTTLDEC << 8))
    201 		ip->ip_sum += htons(IPTTLDEC << 8) + 1;
    202 	else
    203 		ip->ip_sum += htons(IPTTLDEC << 8);
    204 
    205 	/*
    206 	 * Trim the packet in case it's too long..
    207 	 */
    208 	if (m->m_pkthdr.len > iplen) {
    209 		if (m->m_len == m->m_pkthdr.len) {
    210 			m->m_len = iplen;
    211 			m->m_pkthdr.len = iplen;
    212 		} else
    213 			m_adj(m, iplen - m->m_pkthdr.len);
    214 	}
    215 
    216 	/*
    217 	 * Send the packet on it's way.  All we can get back is ENOBUFS
    218 	 */
    219 	ipf->ipf_uses++;
    220 	PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
    221 	if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m,
    222 	    &ipf->ipf_ro.ro_dst, rt)) != 0) {
    223 		if (error == ENOBUFS)
    224 			ipf->ipf_dropped++;
    225 		else
    226 			ipf->ipf_errors++;
    227 	}
    228 	return 1;
    229 }
    230 
    231 static void
    233 ipflow_addstats(
    234 	struct ipflow *ipf)
    235 {
    236 	ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses;
    237 	ipstat.ips_cantforward += ipf->ipf_errors + ipf->ipf_dropped;
    238 	ipstat.ips_forward += ipf->ipf_uses;
    239 	ipstat.ips_fastforward += ipf->ipf_uses;
    240 }
    241 
    242 static void
    243 ipflow_free(
    244 	struct ipflow *ipf)
    245 {
    246 	int s;
    247 	/*
    248 	 * Remove the flow from the hash table (at elevated IPL).
    249 	 * Once it's off the list, we can deal with it at normal
    250 	 * network IPL.
    251 	 */
    252 	s = splimp();
    253 	IPFLOW_REMOVE(ipf);
    254 	splx(s);
    255 	ipflow_addstats(ipf);
    256 	RTFREE(ipf->ipf_ro.ro_rt);
    257 	ipflow_inuse--;
    258 	pool_put(&ipflow_pool, ipf);
    259 }
    260 
    261 struct ipflow *
    262 ipflow_reap(
    263 	int just_one)
    264 {
    265 	while (just_one || ipflow_inuse > ip_maxflows) {
    266 		struct ipflow *ipf, *maybe_ipf = NULL;
    267 		int s;
    268 
    269 		ipf = LIST_FIRST(&ipflowlist);
    270 		while (ipf != NULL) {
    271 			/*
    272 			 * If this no longer points to a valid route
    273 			 * reclaim it.
    274 			 */
    275 			if ((ipf->ipf_ro.ro_rt->rt_flags & RTF_UP) == 0)
    276 				goto done;
    277 			/*
    278 			 * choose the one that's been least recently
    279 			 * used or has had the least uses in the
    280 			 * last 1.5 intervals.
    281 			 */
    282 			if (maybe_ipf == NULL ||
    283 			    ipf->ipf_timer < maybe_ipf->ipf_timer ||
    284 			    (ipf->ipf_timer == maybe_ipf->ipf_timer &&
    285 			     ipf->ipf_last_uses + ipf->ipf_uses <
    286 			         maybe_ipf->ipf_last_uses +
    287 			         maybe_ipf->ipf_uses))
    288 				maybe_ipf = ipf;
    289 			ipf = LIST_NEXT(ipf, ipf_list);
    290 		}
    291 		ipf = maybe_ipf;
    292 	    done:
    293 		/*
    294 		 * Remove the entry from the flow table.
    295 		 */
    296 		s = splimp();
    297 		IPFLOW_REMOVE(ipf);
    298 		splx(s);
    299 		ipflow_addstats(ipf);
    300 		RTFREE(ipf->ipf_ro.ro_rt);
    301 		if (just_one)
    302 			return ipf;
    303 		pool_put(&ipflow_pool, ipf);
    304 		ipflow_inuse--;
    305 	}
    306 	return NULL;
    307 }
    308 
    309 void
    310 ipflow_slowtimo(
    311 	void)
    312 {
    313 	struct ipflow *ipf, *next_ipf;
    314 
    315 	ipf = LIST_FIRST(&ipflowlist);
    316 	while (ipf != NULL) {
    317 		next_ipf = LIST_NEXT(ipf, ipf_list);
    318 		if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer)) {
    319 			ipflow_free(ipf);
    320 		} else {
    321 			ipf->ipf_last_uses = ipf->ipf_uses;
    322 			ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses;
    323 			ipstat.ips_forward += ipf->ipf_uses;
    324 			ipstat.ips_fastforward += ipf->ipf_uses;
    325 			ipf->ipf_uses = 0;
    326 		}
    327 		ipf = next_ipf;
    328 	}
    329 }
    330 
    331 void
    332 ipflow_create(
    333 	const struct route *ro,
    334 	struct mbuf *m)
    335 {
    336 	const struct ip *const ip = mtod(m, struct ip *);
    337 	struct ipflow *ipf;
    338 	unsigned hash;
    339 	int s;
    340 
    341 	/*
    342 	 * Don't create cache entries for ICMP messages.
    343 	 */
    344 	if (ip_maxflows == 0 || ip->ip_p == IPPROTO_ICMP)
    345 		return;
    346 	/*
    347 	 * See if an existing flow struct exists.  If so remove it from it's
    348 	 * list and free the old route.  If not, try to malloc a new one
    349 	 * (if we aren't at our limit).
    350 	 */
    351 	ipf = ipflow_lookup(ip);
    352 	if (ipf == NULL) {
    353 		if (ipflow_inuse >= ip_maxflows) {
    354 			ipf = ipflow_reap(1);
    355 		} else {
    356 			ipf = pool_get(&ipflow_pool, PR_NOWAIT);
    357 			if (ipf == NULL)
    358 				return;
    359 			ipflow_inuse++;
    360 		}
    361 		bzero((caddr_t) ipf, sizeof(*ipf));
    362 	} else {
    363 		s = splimp();
    364 		IPFLOW_REMOVE(ipf);
    365 		splx(s);
    366 		ipflow_addstats(ipf);
    367 		RTFREE(ipf->ipf_ro.ro_rt);
    368 		ipf->ipf_uses = ipf->ipf_last_uses = 0;
    369 		ipf->ipf_errors = ipf->ipf_dropped = 0;
    370 	}
    371 
    372 	/*
    373 	 * Fill in the updated information.
    374 	 */
    375 	ipf->ipf_ro = *ro;
    376 	ro->ro_rt->rt_refcnt++;
    377 	ipf->ipf_dst = ip->ip_dst;
    378 	ipf->ipf_src = ip->ip_src;
    379 	ipf->ipf_tos = ip->ip_tos;
    380 	PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
    381 	ipf->ipf_start = time.tv_sec;
    382 	/*
    383 	 * Insert into the approriate bucket of the flow table.
    384 	 */
    385 	hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos);
    386 	s = splimp();
    387 	IPFLOW_INSERT(&ipflowtable[hash], ipf);
    388 	splx(s);
    389 }
    390