FreeBSD/Linux Kernel Cross Reference
sys/netinet/in_rmx.c
1 /*
2 * Copyright 1994, 1995 Massachusetts Institute of Technology
3 *
4 * Permission to use, copy, modify, and distribute this software and
5 * its documentation for any purpose and without fee is hereby
6 * granted, provided that both the above copyright notice and this
7 * permission notice appear in all copies, that both the above
8 * copyright notice and this permission notice appear in all
9 * supporting documentation, and that the name of M.I.T. not be used
10 * in advertising or publicity pertaining to distribution of the
11 * software without specific, written prior permission. M.I.T. makes
12 * no representations about the suitability of this software for any
13 * purpose. It is provided "as is" without express or implied
14 * warranty.
15 *
16 * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''. M.I.T. DISCLAIMS
17 * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
18 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
20 * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
23 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
25 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
26 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $FreeBSD$
30 */
31
32 /*
33 * This code does two things necessary for the enhanced TCP metrics to
34 * function in a useful manner:
35 * 1) It marks all non-host routes as `cloning', thus ensuring that
36 * every actual reference to such a route actually gets turned
37 * into a reference to a host route to the specific destination
38 * requested.
39 * 2) When such routes lose all their references, it arranges for them
40 * to be deleted in some random collection of circumstances, so that
41 * a large quantity of stale routing data is not kept in kernel memory
42 * indefinitely. See in_rtqtimo() below for the exact mechanism.
43 */
44
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/kernel.h>
48 #include <sys/sysctl.h>
49 #include <sys/socket.h>
50 #include <sys/mbuf.h>
51 #include <sys/syslog.h>
52
53 #include <net/if.h>
54 #include <net/route.h>
55 #include <netinet/in.h>
56 #include <netinet/in_var.h>
57 #include <netinet/ip_var.h>
58
59 extern int in_inithead __P((void **head, int off));
60
61 #define RTPRF_OURS RTF_PROTO3 /* set on routes we manage */
62
63 /*
64 * Do what we need to do when inserting a route.
65 */
66 static struct radix_node *
67 in_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
68 struct radix_node *treenodes)
69 {
70 struct rtentry *rt = (struct rtentry *)treenodes;
71 struct sockaddr_in *sin = (struct sockaddr_in *)rt_key(rt);
72 struct radix_node *ret;
73
74 /*
75 * For IP, all unicast non-host routes are automatically cloning.
76 */
77 if(IN_MULTICAST(ntohl(sin->sin_addr.s_addr)))
78 rt->rt_flags |= RTF_MULTICAST;
79
80 if(!(rt->rt_flags & (RTF_HOST | RTF_CLONING | RTF_MULTICAST))) {
81 rt->rt_flags |= RTF_PRCLONING;
82 }
83
84 /*
85 * A little bit of help for both IP output and input:
86 * For host routes, we make sure that RTF_BROADCAST
87 * is set for anything that looks like a broadcast address.
88 * This way, we can avoid an expensive call to in_broadcast()
89 * in ip_output() most of the time (because the route passed
90 * to ip_output() is almost always a host route).
91 *
92 * We also do the same for local addresses, with the thought
93 * that this might one day be used to speed up ip_input().
94 *
95 * We also mark routes to multicast addresses as such, because
96 * it's easy to do and might be useful (but this is much more
97 * dubious since it's so easy to inspect the address). (This
98 * is done above.)
99 */
100 if (rt->rt_flags & RTF_HOST) {
101 if (in_broadcast(sin->sin_addr, rt->rt_ifp)) {
102 rt->rt_flags |= RTF_BROADCAST;
103 } else {
104 if (satosin(rt->rt_ifa->ifa_addr)->sin_addr.s_addr
105 == sin->sin_addr.s_addr)
106 rt->rt_flags |= RTF_LOCAL;
107 }
108 }
109
110 if (!rt->rt_rmx.rmx_mtu && !(rt->rt_rmx.rmx_locks & RTV_MTU)
111 && rt->rt_ifp)
112 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
113
114 ret = rn_addroute(v_arg, n_arg, head, treenodes);
115 if (ret == NULL && rt->rt_flags & RTF_HOST) {
116 struct rtentry *rt2;
117 /*
118 * We are trying to add a host route, but can't.
119 * Find out if it is because of an
120 * ARP entry and delete it if so.
121 */
122 rt2 = rtalloc1((struct sockaddr *)sin, 0,
123 RTF_CLONING | RTF_PRCLONING);
124 if (rt2) {
125 if (rt2->rt_flags & RTF_LLINFO &&
126 rt2->rt_flags & RTF_HOST &&
127 rt2->rt_gateway &&
128 rt2->rt_gateway->sa_family == AF_LINK) {
129 rtrequest(RTM_DELETE,
130 (struct sockaddr *)rt_key(rt2),
131 rt2->rt_gateway,
132 rt_mask(rt2), rt2->rt_flags, 0);
133 ret = rn_addroute(v_arg, n_arg, head,
134 treenodes);
135 }
136 RTFREE(rt2);
137 }
138 }
139
140 /*
141 * If the new route created successfully, and we are forwarding,
142 * and there is a cached route, free it. Otherwise, we may end
143 * up using the wrong route.
144 */
145 if (ret != NULL && ipforwarding && ipforward_rt.ro_rt) {
146 RTFREE(ipforward_rt.ro_rt);
147 ipforward_rt.ro_rt = 0;
148 }
149
150 return ret;
151 }
152
153 /*
154 * This code is the inverse of in_clsroute: on first reference, if we
155 * were managing the route, stop doing so and set the expiration timer
156 * back off again.
157 */
158 static struct radix_node *
159 in_matroute(void *v_arg, struct radix_node_head *head)
160 {
161 struct radix_node *rn = rn_match(v_arg, head);
162 struct rtentry *rt = (struct rtentry *)rn;
163
164 if(rt && rt->rt_refcnt == 0) { /* this is first reference */
165 if(rt->rt_flags & RTPRF_OURS) {
166 rt->rt_flags &= ~RTPRF_OURS;
167 rt->rt_rmx.rmx_expire = 0;
168 }
169 }
170 return rn;
171 }
172
173 static int rtq_reallyold = 60*60;
174 /* one hour is ``really old'' */
175 SYSCTL_INT(_net_inet_ip, IPCTL_RTEXPIRE, rtexpire, CTLFLAG_RW,
176 &rtq_reallyold , 0,
177 "Default expiration time on dynamically learned routes");
178
179 static int rtq_minreallyold = 10;
180 /* never automatically crank down to less */
181 SYSCTL_INT(_net_inet_ip, IPCTL_RTMINEXPIRE, rtminexpire, CTLFLAG_RW,
182 &rtq_minreallyold , 0,
183 "Minimum time to attempt to hold onto dynamically learned routes");
184
185 static int rtq_toomany = 128;
186 /* 128 cached routes is ``too many'' */
187 SYSCTL_INT(_net_inet_ip, IPCTL_RTMAXCACHE, rtmaxcache, CTLFLAG_RW,
188 &rtq_toomany , 0, "Upper limit on dynamically learned routes");
189
190 /*
191 * On last reference drop, mark the route as belong to us so that it can be
192 * timed out.
193 */
194 static void
195 in_clsroute(struct radix_node *rn, struct radix_node_head *head)
196 {
197 struct rtentry *rt = (struct rtentry *)rn;
198
199 if(!(rt->rt_flags & RTF_UP))
200 return; /* prophylactic measures */
201
202 if((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST)
203 return;
204
205 if (rt->rt_flags & RTPRF_OURS)
206 return;
207
208 if (!(rt->rt_flags & (RTF_WASCLONED | RTF_DYNAMIC)))
209 return;
210
211 /*
212 * As requested by David Greenman:
213 * If rtq_reallyold is 0, just delete the route without
214 * waiting for a timeout cycle to kill it.
215 */
216 if(rtq_reallyold != 0) {
217 rt->rt_flags |= RTPRF_OURS;
218 rt->rt_rmx.rmx_expire = time_second + rtq_reallyold;
219 } else {
220 struct rtentry *dummy;
221
222 /*
223 * rtrequest() would recursively call rtfree() without the
224 * dummy entry argument, causing duplicated free.
225 */
226 rtrequest(RTM_DELETE,
227 (struct sockaddr *)rt_key(rt),
228 rt->rt_gateway, rt_mask(rt),
229 rt->rt_flags, &dummy);
230 }
231 }
232
233 struct rtqk_arg {
234 struct radix_node_head *rnh;
235 int draining;
236 int killed;
237 int found;
238 int updating;
239 time_t nextstop;
240 };
241
242 /*
243 * Get rid of old routes. When draining, this deletes everything, even when
244 * the timeout is not expired yet. When updating, this makes sure that
245 * nothing has a timeout longer than the current value of rtq_reallyold.
246 */
247 static int
248 in_rtqkill(struct radix_node *rn, void *rock)
249 {
250 struct rtqk_arg *ap = rock;
251 struct rtentry *rt = (struct rtentry *)rn;
252 int err;
253
254 if(rt->rt_flags & RTPRF_OURS) {
255 ap->found++;
256
257 if(ap->draining || rt->rt_rmx.rmx_expire <= time_second) {
258 if(rt->rt_refcnt > 0)
259 panic("rtqkill route really not free");
260
261 err = rtrequest(RTM_DELETE,
262 (struct sockaddr *)rt_key(rt),
263 rt->rt_gateway, rt_mask(rt),
264 rt->rt_flags, 0);
265 if(err) {
266 log(LOG_WARNING, "in_rtqkill: error %d\n", err);
267 } else {
268 ap->killed++;
269 }
270 } else {
271 if(ap->updating
272 && (rt->rt_rmx.rmx_expire - time_second
273 > rtq_reallyold)) {
274 rt->rt_rmx.rmx_expire = time_second
275 + rtq_reallyold;
276 }
277 ap->nextstop = lmin(ap->nextstop,
278 rt->rt_rmx.rmx_expire);
279 }
280 }
281
282 return 0;
283 }
284
285 #define RTQ_TIMEOUT 60*10 /* run no less than once every ten minutes */
286 static int rtq_timeout = RTQ_TIMEOUT;
287
288 static void
289 in_rtqtimo(void *rock)
290 {
291 struct radix_node_head *rnh = rock;
292 struct rtqk_arg arg;
293 struct timeval atv;
294 static time_t last_adjusted_timeout = 0;
295 int s;
296
297 arg.found = arg.killed = 0;
298 arg.rnh = rnh;
299 arg.nextstop = time_second + rtq_timeout;
300 arg.draining = arg.updating = 0;
301 s = splnet();
302 rnh->rnh_walktree(rnh, in_rtqkill, &arg);
303 splx(s);
304
305 /*
306 * Attempt to be somewhat dynamic about this:
307 * If there are ``too many'' routes sitting around taking up space,
308 * then crank down the timeout, and see if we can't make some more
309 * go away. However, we make sure that we will never adjust more
310 * than once in rtq_timeout seconds, to keep from cranking down too
311 * hard.
312 */
313 if((arg.found - arg.killed > rtq_toomany)
314 && (time_second - last_adjusted_timeout >= rtq_timeout)
315 && rtq_reallyold > rtq_minreallyold) {
316 rtq_reallyold = 2*rtq_reallyold / 3;
317 if(rtq_reallyold < rtq_minreallyold) {
318 rtq_reallyold = rtq_minreallyold;
319 }
320
321 last_adjusted_timeout = time_second;
322 #ifdef DIAGNOSTIC
323 log(LOG_DEBUG, "in_rtqtimo: adjusted rtq_reallyold to %d\n",
324 rtq_reallyold);
325 #endif
326 arg.found = arg.killed = 0;
327 arg.updating = 1;
328 s = splnet();
329 rnh->rnh_walktree(rnh, in_rtqkill, &arg);
330 splx(s);
331 }
332
333 atv.tv_usec = 0;
334 atv.tv_sec = arg.nextstop - time_second;
335 timeout(in_rtqtimo, rock, tvtohz(&atv));
336 }
337
338 void
339 in_rtqdrain(void)
340 {
341 struct radix_node_head *rnh = rt_tables[AF_INET];
342 struct rtqk_arg arg;
343 int s;
344 arg.found = arg.killed = 0;
345 arg.rnh = rnh;
346 arg.nextstop = 0;
347 arg.draining = 1;
348 arg.updating = 0;
349 s = splnet();
350 rnh->rnh_walktree(rnh, in_rtqkill, &arg);
351 splx(s);
352 }
353
354 /*
355 * Initialize our routing tree.
356 */
357 int
358 in_inithead(void **head, int off)
359 {
360 struct radix_node_head *rnh;
361
362 if(!rn_inithead(head, off))
363 return 0;
364
365 if(head != (void **)&rt_tables[AF_INET]) /* BOGUS! */
366 return 1; /* only do this for the real routing table */
367
368 rnh = *head;
369 rnh->rnh_addaddr = in_addroute;
370 rnh->rnh_matchaddr = in_matroute;
371 rnh->rnh_close = in_clsroute;
372 in_rtqtimo(rnh); /* kick off timeout first time */
373 return 1;
374 }
375
376
377 /*
378 * This zaps old routes when the interface goes down or interface
379 * address is deleted. In the latter case, it deletes static routes
380 * that point to this address. If we don't do this, we may end up
381 * using the old address in the future. The ones we always want to
382 * get rid of are things like ARP entries, since the user might down
383 * the interface, walk over to a completely different network, and
384 * plug back in.
385 */
386 struct in_ifadown_arg {
387 struct radix_node_head *rnh;
388 struct ifaddr *ifa;
389 int del;
390 };
391
392 static int
393 in_ifadownkill(struct radix_node *rn, void *xap)
394 {
395 struct in_ifadown_arg *ap = xap;
396 struct rtentry *rt = (struct rtentry *)rn;
397 int err;
398
399 if (rt->rt_ifa == ap->ifa &&
400 (ap->del || !(rt->rt_flags & RTF_STATIC))) {
401 /*
402 * We need to disable the automatic prune that happens
403 * in this case in rtrequest() because it will blow
404 * away the pointers that rn_walktree() needs in order
405 * continue our descent. We will end up deleting all
406 * the routes that rtrequest() would have in any case,
407 * so that behavior is not needed there.
408 */
409 rt->rt_flags &= ~(RTF_CLONING | RTF_PRCLONING);
410 err = rtrequest(RTM_DELETE, (struct sockaddr *)rt_key(rt),
411 rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0);
412 if (err) {
413 log(LOG_WARNING, "in_ifadownkill: error %d\n", err);
414 }
415 }
416 return 0;
417 }
418
419 int
420 in_ifadown(struct ifaddr *ifa, int delete)
421 {
422 struct in_ifadown_arg arg;
423 struct radix_node_head *rnh;
424
425 if (ifa->ifa_addr->sa_family != AF_INET)
426 return 1;
427
428 arg.rnh = rnh = rt_tables[AF_INET];
429 arg.ifa = ifa;
430 arg.del = delete;
431 rnh->rnh_walktree(rnh, in_ifadownkill, &arg);
432 ifa->ifa_flags &= ~IFA_ROUTE;
433 return 0;
434 }
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