2 * Copyright 1994, 1995 Massachusetts Institute of Technology
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29 * $FreeBSD: src/sys/netinet/in_rmx.c,v 1.37.2.3 2002/08/09 14:49:23 ru Exp $
30 * $DragonFly: src/sys/netinet/in_rmx.c,v 1.5 2004/09/16 23:14:29 joerg Exp $
34 * This code does two things necessary for the enhanced TCP metrics to
35 * function in a useful manner:
36 * 1) It marks all non-host routes as `cloning', thus ensuring that
37 * every actual reference to such a route actually gets turned
38 * into a reference to a host route to the specific destination
40 * 2) When such routes lose all their references, it arranges for them
41 * to be deleted in some random collection of circumstances, so that
42 * a large quantity of stale routing data is not kept in kernel memory
43 * indefinitely. See in_rtqtimo() below for the exact mechanism.
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/kernel.h>
49 #include <sys/sysctl.h>
50 #include <sys/socket.h>
52 #include <sys/syslog.h>
55 #include <net/route.h>
56 #include <netinet/in.h>
57 #include <netinet/in_var.h>
58 #include <netinet/ip_var.h>
60 static struct callout in_rtqtimo_ch;
62 extern int in_inithead (void **head, int off);
64 #define RTPRF_OURS RTF_PROTO3 /* set on routes we manage */
67 * Do what we need to do when inserting a route.
69 static struct radix_node *
70 in_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
71 struct radix_node *treenodes)
73 struct rtentry *rt = (struct rtentry *)treenodes;
74 struct sockaddr_in *sin = (struct sockaddr_in *)rt_key(rt);
75 struct radix_node *ret;
78 * For IP, all unicast non-host routes are automatically cloning.
80 if(IN_MULTICAST(ntohl(sin->sin_addr.s_addr)))
81 rt->rt_flags |= RTF_MULTICAST;
83 if(!(rt->rt_flags & (RTF_HOST | RTF_CLONING | RTF_MULTICAST))) {
84 rt->rt_flags |= RTF_PRCLONING;
88 * A little bit of help for both IP output and input:
89 * For host routes, we make sure that RTF_BROADCAST
90 * is set for anything that looks like a broadcast address.
91 * This way, we can avoid an expensive call to in_broadcast()
92 * in ip_output() most of the time (because the route passed
93 * to ip_output() is almost always a host route).
95 * We also do the same for local addresses, with the thought
96 * that this might one day be used to speed up ip_input().
98 * We also mark routes to multicast addresses as such, because
99 * it's easy to do and might be useful (but this is much more
100 * dubious since it's so easy to inspect the address). (This
103 if (rt->rt_flags & RTF_HOST) {
104 if (in_broadcast(sin->sin_addr, rt->rt_ifp)) {
105 rt->rt_flags |= RTF_BROADCAST;
107 if (satosin(rt->rt_ifa->ifa_addr)->sin_addr.s_addr
108 == sin->sin_addr.s_addr)
109 rt->rt_flags |= RTF_LOCAL;
113 if (!rt->rt_rmx.rmx_mtu && !(rt->rt_rmx.rmx_locks & RTV_MTU)
115 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
117 ret = rn_addroute(v_arg, n_arg, head, treenodes);
118 if (ret == NULL && rt->rt_flags & RTF_HOST) {
121 * We are trying to add a host route, but can't.
122 * Find out if it is because of an
123 * ARP entry and delete it if so.
125 rt2 = rtalloc1((struct sockaddr *)sin, 0,
126 RTF_CLONING | RTF_PRCLONING);
128 if (rt2->rt_flags & RTF_LLINFO &&
129 rt2->rt_flags & RTF_HOST &&
131 rt2->rt_gateway->sa_family == AF_LINK) {
132 rtrequest(RTM_DELETE,
133 (struct sockaddr *)rt_key(rt2),
135 rt_mask(rt2), rt2->rt_flags, 0);
136 ret = rn_addroute(v_arg, n_arg, head,
144 * If the new route created successfully, and we are forwarding,
145 * and there is a cached route, free it. Otherwise, we may end
146 * up using the wrong route.
148 if (ret != NULL && ipforwarding && ipforward_rt.ro_rt) {
149 RTFREE(ipforward_rt.ro_rt);
150 ipforward_rt.ro_rt = 0;
157 * This code is the inverse of in_clsroute: on first reference, if we
158 * were managing the route, stop doing so and set the expiration timer
161 static struct radix_node *
162 in_matroute(void *v_arg, struct radix_node_head *head)
164 struct radix_node *rn = rn_match(v_arg, head);
165 struct rtentry *rt = (struct rtentry *)rn;
167 if(rt && rt->rt_refcnt == 0) { /* this is first reference */
168 if(rt->rt_flags & RTPRF_OURS) {
169 rt->rt_flags &= ~RTPRF_OURS;
170 rt->rt_rmx.rmx_expire = 0;
176 static int rtq_reallyold = 60*60;
177 /* one hour is ``really old'' */
178 SYSCTL_INT(_net_inet_ip, IPCTL_RTEXPIRE, rtexpire, CTLFLAG_RW,
180 "Default expiration time on dynamically learned routes");
182 static int rtq_minreallyold = 10;
183 /* never automatically crank down to less */
184 SYSCTL_INT(_net_inet_ip, IPCTL_RTMINEXPIRE, rtminexpire, CTLFLAG_RW,
185 &rtq_minreallyold , 0,
186 "Minimum time to attempt to hold onto dynamically learned routes");
188 static int rtq_toomany = 128;
189 /* 128 cached routes is ``too many'' */
190 SYSCTL_INT(_net_inet_ip, IPCTL_RTMAXCACHE, rtmaxcache, CTLFLAG_RW,
191 &rtq_toomany , 0, "Upper limit on dynamically learned routes");
194 * On last reference drop, mark the route as belong to us so that it can be
198 in_clsroute(struct radix_node *rn, struct radix_node_head *head)
200 struct rtentry *rt = (struct rtentry *)rn;
202 if(!(rt->rt_flags & RTF_UP))
203 return; /* prophylactic measures */
205 if((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST)
208 if((rt->rt_flags & (RTF_WASCLONED | RTPRF_OURS))
213 * As requested by David Greenman:
214 * If rtq_reallyold is 0, just delete the route without
215 * waiting for a timeout cycle to kill it.
217 if(rtq_reallyold != 0) {
218 rt->rt_flags |= RTPRF_OURS;
219 rt->rt_rmx.rmx_expire = time_second + rtq_reallyold;
221 rtrequest(RTM_DELETE,
222 (struct sockaddr *)rt_key(rt),
223 rt->rt_gateway, rt_mask(rt),
229 struct radix_node_head *rnh;
238 * Get rid of old routes. When draining, this deletes everything, even when
239 * the timeout is not expired yet. When updating, this makes sure that
240 * nothing has a timeout longer than the current value of rtq_reallyold.
243 in_rtqkill(struct radix_node *rn, void *rock)
245 struct rtqk_arg *ap = rock;
246 struct rtentry *rt = (struct rtentry *)rn;
249 if(rt->rt_flags & RTPRF_OURS) {
252 if(ap->draining || rt->rt_rmx.rmx_expire <= time_second) {
253 if(rt->rt_refcnt > 0)
254 panic("rtqkill route really not free");
256 err = rtrequest(RTM_DELETE,
257 (struct sockaddr *)rt_key(rt),
258 rt->rt_gateway, rt_mask(rt),
261 log(LOG_WARNING, "in_rtqkill: error %d\n", err);
267 && (rt->rt_rmx.rmx_expire - time_second
269 rt->rt_rmx.rmx_expire = time_second
272 ap->nextstop = lmin(ap->nextstop,
273 rt->rt_rmx.rmx_expire);
280 #define RTQ_TIMEOUT 60*10 /* run no less than once every ten minutes */
281 static int rtq_timeout = RTQ_TIMEOUT;
284 in_rtqtimo(void *rock)
286 struct radix_node_head *rnh = rock;
289 static time_t last_adjusted_timeout = 0;
292 arg.found = arg.killed = 0;
294 arg.nextstop = time_second + rtq_timeout;
295 arg.draining = arg.updating = 0;
297 rnh->rnh_walktree(rnh, in_rtqkill, &arg);
301 * Attempt to be somewhat dynamic about this:
302 * If there are ``too many'' routes sitting around taking up space,
303 * then crank down the timeout, and see if we can't make some more
304 * go away. However, we make sure that we will never adjust more
305 * than once in rtq_timeout seconds, to keep from cranking down too
308 if((arg.found - arg.killed > rtq_toomany)
309 && (time_second - last_adjusted_timeout >= rtq_timeout)
310 && rtq_reallyold > rtq_minreallyold) {
311 rtq_reallyold = 2*rtq_reallyold / 3;
312 if(rtq_reallyold < rtq_minreallyold) {
313 rtq_reallyold = rtq_minreallyold;
316 last_adjusted_timeout = time_second;
318 log(LOG_DEBUG, "in_rtqtimo: adjusted rtq_reallyold to %d\n",
321 arg.found = arg.killed = 0;
324 rnh->rnh_walktree(rnh, in_rtqkill, &arg);
329 atv.tv_sec = arg.nextstop - time_second;
330 callout_reset(&in_rtqtimo_ch, tvtohz_high(&atv), in_rtqtimo, rock);
336 struct radix_node_head *rnh = rt_tables[AF_INET];
339 arg.found = arg.killed = 0;
345 rnh->rnh_walktree(rnh, in_rtqkill, &arg);
350 * Initialize our routing tree.
353 in_inithead(void **head, int off)
355 struct radix_node_head *rnh;
357 if(!rn_inithead(head, off))
360 if(head != (void **)&rt_tables[AF_INET]) /* BOGUS! */
361 return 1; /* only do this for the real routing table */
364 rnh->rnh_addaddr = in_addroute;
365 rnh->rnh_matchaddr = in_matroute;
366 rnh->rnh_close = in_clsroute;
367 callout_init(&in_rtqtimo_ch);
368 in_rtqtimo(rnh); /* kick off timeout first time */
374 * This zaps old routes when the interface goes down or interface
375 * address is deleted. In the latter case, it deletes static routes
376 * that point to this address. If we don't do this, we may end up
377 * using the old address in the future. The ones we always want to
378 * get rid of are things like ARP entries, since the user might down
379 * the interface, walk over to a completely different network, and
382 struct in_ifadown_arg {
383 struct radix_node_head *rnh;
389 in_ifadownkill(struct radix_node *rn, void *xap)
391 struct in_ifadown_arg *ap = xap;
392 struct rtentry *rt = (struct rtentry *)rn;
395 if (rt->rt_ifa == ap->ifa &&
396 (ap->del || !(rt->rt_flags & RTF_STATIC))) {
398 * We need to disable the automatic prune that happens
399 * in this case in rtrequest() because it will blow
400 * away the pointers that rn_walktree() needs in order
401 * continue our descent. We will end up deleting all
402 * the routes that rtrequest() would have in any case,
403 * so that behavior is not needed there.
405 rt->rt_flags &= ~(RTF_CLONING | RTF_PRCLONING);
406 err = rtrequest(RTM_DELETE, (struct sockaddr *)rt_key(rt),
407 rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0);
409 log(LOG_WARNING, "in_ifadownkill: error %d\n", err);
416 in_ifadown(struct ifaddr *ifa, int delete)
418 struct in_ifadown_arg arg;
419 struct radix_node_head *rnh;
421 if (ifa->ifa_addr->sa_family != AF_INET)
424 arg.rnh = rnh = rt_tables[AF_INET];
427 rnh->rnh_walktree(rnh, in_ifadownkill, &arg);
428 ifa->ifa_flags &= ~IFA_ROUTE;