FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_flow.c
1 /* $NetBSD: ip_flow.c,v 1.27 2003/12/12 21:17:59 scw 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/cdefs.h>
40 __KERNEL_RCSID(0, "$NetBSD: ip_flow.c,v 1.27 2003/12/12 21:17:59 scw Exp $");
41
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/malloc.h>
45 #include <sys/mbuf.h>
46 #include <sys/domain.h>
47 #include <sys/protosw.h>
48 #include <sys/socket.h>
49 #include <sys/socketvar.h>
50 #include <sys/errno.h>
51 #include <sys/time.h>
52 #include <sys/kernel.h>
53 #include <sys/pool.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 (/*CONSTCOND*/ 0)
84
85 #define IPFLOW_REMOVE(ipf) \
86 do { \
87 LIST_REMOVE((ipf), ipf_hash); \
88 LIST_REMOVE((ipf), ipf_list); \
89 } while (/*CONSTCOND*/ 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 NULL);
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, ip_store;
147 struct ipflow *ipf;
148 struct rtentry *rt;
149 struct sockaddr *dst;
150 int error;
151 int iplen;
152
153 /*
154 * Are we forwarding packets? Big enough for an IP packet?
155 */
156 if (!ipforwarding || ipflow_inuse == 0 || m->m_len < sizeof(struct ip))
157 return 0;
158
159 /*
160 * Was packet received as a link-level multicast or broadcast?
161 * If so, don't try to fast forward..
162 */
163 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0)
164 return 0;
165
166 /*
167 * IP header with no option and valid version and length
168 */
169 if (IP_HDR_ALIGNED_P(mtod(m, caddr_t)))
170 ip = mtod(m, struct ip *);
171 else {
172 memcpy(&ip_store, mtod(m, caddr_t), sizeof(ip_store));
173 ip = &ip_store;
174 }
175 iplen = ntohs(ip->ip_len);
176 if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) ||
177 iplen < sizeof(struct ip) || iplen > m->m_pkthdr.len)
178 return 0;
179 /*
180 * Find a flow.
181 */
182 if ((ipf = ipflow_lookup(ip)) == NULL)
183 return 0;
184
185 /*
186 * Verify the IP header checksum.
187 */
188 switch (m->m_pkthdr.csum_flags &
189 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_IPv4) |
190 M_CSUM_IPv4_BAD)) {
191 case M_CSUM_IPv4|M_CSUM_IPv4_BAD:
192 return (0);
193
194 case M_CSUM_IPv4:
195 /* Checksum was okay. */
196 break;
197
198 default:
199 /* Must compute it ourselves. */
200 if (in_cksum(m, sizeof(struct ip)) != 0)
201 return (0);
202 break;
203 }
204
205 /*
206 * Route and interface still up?
207 */
208 rt = ipf->ipf_ro.ro_rt;
209 if ((rt->rt_flags & RTF_UP) == 0 ||
210 (rt->rt_ifp->if_flags & IFF_UP) == 0)
211 return 0;
212
213 /*
214 * Packet size OK? TTL?
215 */
216 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC)
217 return 0;
218
219 /*
220 * Clear any in-bound checksum flags for this packet.
221 */
222 m->m_pkthdr.csum_flags = 0;
223
224 /*
225 * Everything checks out and so we can forward this packet.
226 * Modify the TTL and incrementally change the checksum.
227 *
228 * This method of adding the checksum works on either endian CPU.
229 * If htons() is inlined, all the arithmetic is folded; otherwise
230 * the htons()s are combined by CSE due to the __const__ attribute.
231 *
232 * Don't bother using HW checksumming here -- the incremental
233 * update is pretty fast.
234 */
235 ip->ip_ttl -= IPTTLDEC;
236 if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8))
237 ip->ip_sum -= ~htons(IPTTLDEC << 8);
238 else
239 ip->ip_sum += htons(IPTTLDEC << 8);
240
241 /*
242 * Done modifying the header; copy it back, if necessary.
243 */
244 if (IP_HDR_ALIGNED_P(mtod(m, caddr_t)) == 0)
245 memcpy(mtod(m, caddr_t), &ip_store, sizeof(ip_store));
246
247 /*
248 * Trim the packet in case it's too long..
249 */
250 if (m->m_pkthdr.len > iplen) {
251 if (m->m_len == m->m_pkthdr.len) {
252 m->m_len = iplen;
253 m->m_pkthdr.len = iplen;
254 } else
255 m_adj(m, iplen - m->m_pkthdr.len);
256 }
257
258 /*
259 * Send the packet on it's way. All we can get back is ENOBUFS
260 */
261 ipf->ipf_uses++;
262 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
263
264 if (rt->rt_flags & RTF_GATEWAY)
265 dst = rt->rt_gateway;
266 else
267 dst = &ipf->ipf_ro.ro_dst;
268
269 if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, dst, rt)) != 0) {
270 if (error == ENOBUFS)
271 ipf->ipf_dropped++;
272 else
273 ipf->ipf_errors++;
274 }
275 return 1;
276 }
277
278 static void
279 ipflow_addstats(
280 struct ipflow *ipf)
281 {
282 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses;
283 ipstat.ips_cantforward += ipf->ipf_errors + ipf->ipf_dropped;
284 ipstat.ips_forward += ipf->ipf_uses;
285 ipstat.ips_fastforward += ipf->ipf_uses;
286 }
287
288 static void
289 ipflow_free(
290 struct ipflow *ipf)
291 {
292 int s;
293 /*
294 * Remove the flow from the hash table (at elevated IPL).
295 * Once it's off the list, we can deal with it at normal
296 * network IPL.
297 */
298 s = splnet();
299 IPFLOW_REMOVE(ipf);
300 splx(s);
301 ipflow_addstats(ipf);
302 RTFREE(ipf->ipf_ro.ro_rt);
303 ipflow_inuse--;
304 pool_put(&ipflow_pool, ipf);
305 }
306
307 struct ipflow *
308 ipflow_reap(
309 int just_one)
310 {
311 while (just_one || ipflow_inuse > ip_maxflows) {
312 struct ipflow *ipf, *maybe_ipf = NULL;
313 int s;
314
315 ipf = LIST_FIRST(&ipflowlist);
316 while (ipf != NULL) {
317 /*
318 * If this no longer points to a valid route
319 * reclaim it.
320 */
321 if ((ipf->ipf_ro.ro_rt->rt_flags & RTF_UP) == 0)
322 goto done;
323 /*
324 * choose the one that's been least recently
325 * used or has had the least uses in the
326 * last 1.5 intervals.
327 */
328 if (maybe_ipf == NULL ||
329 ipf->ipf_timer < maybe_ipf->ipf_timer ||
330 (ipf->ipf_timer == maybe_ipf->ipf_timer &&
331 ipf->ipf_last_uses + ipf->ipf_uses <
332 maybe_ipf->ipf_last_uses +
333 maybe_ipf->ipf_uses))
334 maybe_ipf = ipf;
335 ipf = LIST_NEXT(ipf, ipf_list);
336 }
337 ipf = maybe_ipf;
338 done:
339 /*
340 * Remove the entry from the flow table.
341 */
342 s = splnet();
343 IPFLOW_REMOVE(ipf);
344 splx(s);
345 ipflow_addstats(ipf);
346 RTFREE(ipf->ipf_ro.ro_rt);
347 if (just_one)
348 return ipf;
349 pool_put(&ipflow_pool, ipf);
350 ipflow_inuse--;
351 }
352 return NULL;
353 }
354
355 void
356 ipflow_slowtimo(
357 void)
358 {
359 struct ipflow *ipf, *next_ipf;
360
361 ipf = LIST_FIRST(&ipflowlist);
362 while (ipf != NULL) {
363 next_ipf = LIST_NEXT(ipf, ipf_list);
364 if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer)) {
365 ipflow_free(ipf);
366 } else {
367 ipf->ipf_last_uses = ipf->ipf_uses;
368 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses;
369 ipstat.ips_forward += ipf->ipf_uses;
370 ipstat.ips_fastforward += ipf->ipf_uses;
371 ipf->ipf_uses = 0;
372 }
373 ipf = next_ipf;
374 }
375 }
376
377 void
378 ipflow_create(
379 const struct route *ro,
380 struct mbuf *m)
381 {
382 const struct ip *const ip = mtod(m, struct ip *);
383 struct ipflow *ipf;
384 unsigned hash;
385 int s;
386
387 /*
388 * Don't create cache entries for ICMP messages.
389 */
390 if (ip_maxflows == 0 || ip->ip_p == IPPROTO_ICMP)
391 return;
392 /*
393 * See if an existing flow struct exists. If so remove it from it's
394 * list and free the old route. If not, try to malloc a new one
395 * (if we aren't at our limit).
396 */
397 ipf = ipflow_lookup(ip);
398 if (ipf == NULL) {
399 if (ipflow_inuse >= ip_maxflows) {
400 ipf = ipflow_reap(1);
401 } else {
402 ipf = pool_get(&ipflow_pool, PR_NOWAIT);
403 if (ipf == NULL)
404 return;
405 ipflow_inuse++;
406 }
407 bzero((caddr_t) ipf, sizeof(*ipf));
408 } else {
409 s = splnet();
410 IPFLOW_REMOVE(ipf);
411 splx(s);
412 ipflow_addstats(ipf);
413 RTFREE(ipf->ipf_ro.ro_rt);
414 ipf->ipf_uses = ipf->ipf_last_uses = 0;
415 ipf->ipf_errors = ipf->ipf_dropped = 0;
416 }
417
418 /*
419 * Fill in the updated information.
420 */
421 ipf->ipf_ro = *ro;
422 ro->ro_rt->rt_refcnt++;
423 ipf->ipf_dst = ip->ip_dst;
424 ipf->ipf_src = ip->ip_src;
425 ipf->ipf_tos = ip->ip_tos;
426 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
427 ipf->ipf_start = time.tv_sec;
428 /*
429 * Insert into the approriate bucket of the flow table.
430 */
431 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos);
432 s = splnet();
433 IPFLOW_INSERT(&ipflowtable[hash], ipf);
434 splx(s);
435 }
436
437 void
438 ipflow_invalidate_all(
439 void)
440 {
441 struct ipflow *ipf, *next_ipf;
442 int s;
443
444 s = splnet();
445 ipf = LIST_FIRST(&ipflowlist);
446 for (ipf = LIST_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) {
447 next_ipf = LIST_NEXT(ipf, ipf_list);
448 ipflow_free(ipf);
449 }
450 splx(s);
451 }
Cache object: ab67847d229b90c178f4a47e77998911
|