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: releng/5.0/sys/netinet/in_rmx.c 92723 2002-03-19 21:25:46Z alfred $
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(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 & (RTF_WASCLONED | RTPRF_OURS))
206 != RTF_WASCLONED)
207 return;
208
209 /*
210 * As requested by David Greenman:
211 * If rtq_reallyold is 0, just delete the route without
212 * waiting for a timeout cycle to kill it.
213 */
214 if(rtq_reallyold != 0) {
215 rt->rt_flags |= RTPRF_OURS;
216 rt->rt_rmx.rmx_expire = time_second + rtq_reallyold;
217 } else {
218 rtrequest(RTM_DELETE,
219 (struct sockaddr *)rt_key(rt),
220 rt->rt_gateway, rt_mask(rt),
221 rt->rt_flags, 0);
222 }
223 }
224
225 struct rtqk_arg {
226 struct radix_node_head *rnh;
227 int draining;
228 int killed;
229 int found;
230 int updating;
231 time_t nextstop;
232 };
233
234 /*
235 * Get rid of old routes. When draining, this deletes everything, even when
236 * the timeout is not expired yet. When updating, this makes sure that
237 * nothing has a timeout longer than the current value of rtq_reallyold.
238 */
239 static int
240 in_rtqkill(struct radix_node *rn, void *rock)
241 {
242 struct rtqk_arg *ap = rock;
243 struct rtentry *rt = (struct rtentry *)rn;
244 int err;
245
246 if(rt->rt_flags & RTPRF_OURS) {
247 ap->found++;
248
249 if(ap->draining || rt->rt_rmx.rmx_expire <= time_second) {
250 if(rt->rt_refcnt > 0)
251 panic("rtqkill route really not free");
252
253 err = rtrequest(RTM_DELETE,
254 (struct sockaddr *)rt_key(rt),
255 rt->rt_gateway, rt_mask(rt),
256 rt->rt_flags, 0);
257 if(err) {
258 log(LOG_WARNING, "in_rtqkill: error %d\n", err);
259 } else {
260 ap->killed++;
261 }
262 } else {
263 if(ap->updating
264 && (rt->rt_rmx.rmx_expire - time_second
265 > rtq_reallyold)) {
266 rt->rt_rmx.rmx_expire = time_second
267 + rtq_reallyold;
268 }
269 ap->nextstop = lmin(ap->nextstop,
270 rt->rt_rmx.rmx_expire);
271 }
272 }
273
274 return 0;
275 }
276
277 #define RTQ_TIMEOUT 60*10 /* run no less than once every ten minutes */
278 static int rtq_timeout = RTQ_TIMEOUT;
279
280 static void
281 in_rtqtimo(void *rock)
282 {
283 struct radix_node_head *rnh = rock;
284 struct rtqk_arg arg;
285 struct timeval atv;
286 static time_t last_adjusted_timeout = 0;
287 int s;
288
289 arg.found = arg.killed = 0;
290 arg.rnh = rnh;
291 arg.nextstop = time_second + rtq_timeout;
292 arg.draining = arg.updating = 0;
293 s = splnet();
294 rnh->rnh_walktree(rnh, in_rtqkill, &arg);
295 splx(s);
296
297 /*
298 * Attempt to be somewhat dynamic about this:
299 * If there are ``too many'' routes sitting around taking up space,
300 * then crank down the timeout, and see if we can't make some more
301 * go away. However, we make sure that we will never adjust more
302 * than once in rtq_timeout seconds, to keep from cranking down too
303 * hard.
304 */
305 if((arg.found - arg.killed > rtq_toomany)
306 && (time_second - last_adjusted_timeout >= rtq_timeout)
307 && rtq_reallyold > rtq_minreallyold) {
308 rtq_reallyold = 2*rtq_reallyold / 3;
309 if(rtq_reallyold < rtq_minreallyold) {
310 rtq_reallyold = rtq_minreallyold;
311 }
312
313 last_adjusted_timeout = time_second;
314 #ifdef DIAGNOSTIC
315 log(LOG_DEBUG, "in_rtqtimo: adjusted rtq_reallyold to %d\n",
316 rtq_reallyold);
317 #endif
318 arg.found = arg.killed = 0;
319 arg.updating = 1;
320 s = splnet();
321 rnh->rnh_walktree(rnh, in_rtqkill, &arg);
322 splx(s);
323 }
324
325 atv.tv_usec = 0;
326 atv.tv_sec = arg.nextstop - time_second;
327 timeout(in_rtqtimo, rock, tvtohz(&atv));
328 }
329
330 void
331 in_rtqdrain(void)
332 {
333 struct radix_node_head *rnh = rt_tables[AF_INET];
334 struct rtqk_arg arg;
335 int s;
336 arg.found = arg.killed = 0;
337 arg.rnh = rnh;
338 arg.nextstop = 0;
339 arg.draining = 1;
340 arg.updating = 0;
341 s = splnet();
342 rnh->rnh_walktree(rnh, in_rtqkill, &arg);
343 splx(s);
344 }
345
346 /*
347 * Initialize our routing tree.
348 */
349 int
350 in_inithead(void **head, int off)
351 {
352 struct radix_node_head *rnh;
353
354 if(!rn_inithead(head, off))
355 return 0;
356
357 if(head != (void **)&rt_tables[AF_INET]) /* BOGUS! */
358 return 1; /* only do this for the real routing table */
359
360 rnh = *head;
361 rnh->rnh_addaddr = in_addroute;
362 rnh->rnh_matchaddr = in_matroute;
363 rnh->rnh_close = in_clsroute;
364 in_rtqtimo(rnh); /* kick off timeout first time */
365 return 1;
366 }
367
368
369 /*
370 * This zaps old routes when the interface goes down or interface
371 * address is deleted. In the latter case, it deletes static routes
372 * that point to this address. If we don't do this, we may end up
373 * using the old address in the future. The ones we always want to
374 * get rid of are things like ARP entries, since the user might down
375 * the interface, walk over to a completely different network, and
376 * plug back in.
377 */
378 struct in_ifadown_arg {
379 struct radix_node_head *rnh;
380 struct ifaddr *ifa;
381 int del;
382 };
383
384 static int
385 in_ifadownkill(struct radix_node *rn, void *xap)
386 {
387 struct in_ifadown_arg *ap = xap;
388 struct rtentry *rt = (struct rtentry *)rn;
389 int err;
390
391 if (rt->rt_ifa == ap->ifa &&
392 (ap->del || !(rt->rt_flags & RTF_STATIC))) {
393 /*
394 * We need to disable the automatic prune that happens
395 * in this case in rtrequest() because it will blow
396 * away the pointers that rn_walktree() needs in order
397 * continue our descent. We will end up deleting all
398 * the routes that rtrequest() would have in any case,
399 * so that behavior is not needed there.
400 */
401 rt->rt_flags &= ~(RTF_CLONING | RTF_PRCLONING);
402 err = rtrequest(RTM_DELETE, (struct sockaddr *)rt_key(rt),
403 rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0);
404 if (err) {
405 log(LOG_WARNING, "in_ifadownkill: error %d\n", err);
406 }
407 }
408 return 0;
409 }
410
411 int
412 in_ifadown(struct ifaddr *ifa, int delete)
413 {
414 struct in_ifadown_arg arg;
415 struct radix_node_head *rnh;
416
417 if (ifa->ifa_addr->sa_family != AF_INET)
418 return 1;
419
420 arg.rnh = rnh = rt_tables[AF_INET];
421 arg.ifa = ifa;
422 arg.del = delete;
423 rnh->rnh_walktree(rnh, in_ifadownkill, &arg);
424 ifa->ifa_flags &= ~IFA_ROUTE;
425 return 0;
426 }
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