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 * $Id: in_rmx.c,v 1.34 1998/03/30 09:52:46 phk Exp $ 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 58 extern int in_inithead __P((void **head, int off)); 59 60 #define RTPRF_OURS RTF_PROTO3 /* set on routes we manage */ 61 62 /* 63 * Do what we need to do when inserting a route. 64 */ 65 static struct radix_node * 66 in_addroute(void *v_arg, void *n_arg, struct radix_node_head *head, 67 struct radix_node *treenodes) 68 { 69 struct rtentry *rt = (struct rtentry *)treenodes; 70 struct sockaddr_in *sin = (struct sockaddr_in *)rt_key(rt); 71 struct radix_node *ret; 72 73 /* 74 * For IP, all unicast non-host routes are automatically cloning. 75 */ 76 if(IN_MULTICAST(ntohl(sin->sin_addr.s_addr))) 77 rt->rt_flags |= RTF_MULTICAST; 78 79 if(!(rt->rt_flags & (RTF_HOST | RTF_CLONING | RTF_MULTICAST))) { 80 rt->rt_flags |= RTF_PRCLONING; 81 } 82 83 /* 84 * A little bit of help for both IP output and input: 85 * For host routes, we make sure that RTF_BROADCAST 86 * is set for anything that looks like a broadcast address. 87 * This way, we can avoid an expensive call to in_broadcast() 88 * in ip_output() most of the time (because the route passed 89 * to ip_output() is almost always a host route). 90 * 91 * We also do the same for local addresses, with the thought 92 * that this might one day be used to speed up ip_input(). 93 * 94 * We also mark routes to multicast addresses as such, because 95 * it's easy to do and might be useful (but this is much more 96 * dubious since it's so easy to inspect the address). (This 97 * is done above.) 98 */ 99 if (rt->rt_flags & RTF_HOST) { 100 if (in_broadcast(sin->sin_addr, rt->rt_ifp)) { 101 rt->rt_flags |= RTF_BROADCAST; 102 } else { 103 #define satosin(sa) ((struct sockaddr_in *)sa) 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 #undef satosin 108 } 109 } 110 111 if (!rt->rt_rmx.rmx_mtu && !(rt->rt_rmx.rmx_locks & RTV_MTU) 112 && rt->rt_ifp) 113 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu; 114 115 ret = rn_addroute(v_arg, n_arg, head, treenodes); 116 if (ret == NULL && rt->rt_flags & RTF_HOST) { 117 struct rtentry *rt2; 118 /* 119 * We are trying to add a host route, but can't. 120 * Find out if it is because of an 121 * ARP entry and delete it if so. 122 */ 123 rt2 = rtalloc1((struct sockaddr *)sin, 0, 124 RTF_CLONING | RTF_PRCLONING); 125 if (rt2) { 126 if (rt2->rt_flags & RTF_LLINFO && 127 rt2->rt_flags & RTF_HOST && 128 rt2->rt_gateway && 129 rt2->rt_gateway->sa_family == AF_LINK) { 130 rtrequest(RTM_DELETE, 131 (struct sockaddr *)rt_key(rt2), 132 rt2->rt_gateway, 133 rt_mask(rt2), rt2->rt_flags, 0); 134 ret = rn_addroute(v_arg, n_arg, head, 135 treenodes); 136 } 137 RTFREE(rt2); 138 } 139 } 140 return ret; 141 } 142 143 /* 144 * This code is the inverse of in_clsroute: on first reference, if we 145 * were managing the route, stop doing so and set the expiration timer 146 * back off again. 147 */ 148 static struct radix_node * 149 in_matroute(void *v_arg, struct radix_node_head *head) 150 { 151 struct radix_node *rn = rn_match(v_arg, head); 152 struct rtentry *rt = (struct rtentry *)rn; 153 154 if(rt && rt->rt_refcnt == 0) { /* this is first reference */ 155 if(rt->rt_flags & RTPRF_OURS) { 156 rt->rt_flags &= ~RTPRF_OURS; 157 rt->rt_rmx.rmx_expire = 0; 158 } 159 } 160 return rn; 161 } 162 163 static int rtq_reallyold = 60*60; 164 /* one hour is ``really old'' */ 165 SYSCTL_INT(_net_inet_ip, IPCTL_RTEXPIRE, rtexpire, 166 CTLFLAG_RW, &rtq_reallyold , 0, ""); 167 168 static int rtq_minreallyold = 10; 169 /* never automatically crank down to less */ 170 SYSCTL_INT(_net_inet_ip, IPCTL_RTMINEXPIRE, rtminexpire, 171 CTLFLAG_RW, &rtq_minreallyold , 0, ""); 172 173 static int rtq_toomany = 128; 174 /* 128 cached routes is ``too many'' */ 175 SYSCTL_INT(_net_inet_ip, IPCTL_RTMAXCACHE, rtmaxcache, 176 CTLFLAG_RW, &rtq_toomany , 0, ""); 177 178 179 /* 180 * On last reference drop, mark the route as belong to us so that it can be 181 * timed out. 182 */ 183 static void 184 in_clsroute(struct radix_node *rn, struct radix_node_head *head) 185 { 186 struct rtentry *rt = (struct rtentry *)rn; 187 188 if(!(rt->rt_flags & RTF_UP)) 189 return; /* prophylactic measures */ 190 191 if((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST) 192 return; 193 194 if((rt->rt_flags & (RTF_WASCLONED | RTPRF_OURS)) 195 != RTF_WASCLONED) 196 return; 197 198 /* 199 * As requested by David Greenman: 200 * If rtq_reallyold is 0, just delete the route without 201 * waiting for a timeout cycle to kill it. 202 */ 203 if(rtq_reallyold != 0) { 204 rt->rt_flags |= RTPRF_OURS; 205 rt->rt_rmx.rmx_expire = time_second + rtq_reallyold; 206 } else { 207 rtrequest(RTM_DELETE, 208 (struct sockaddr *)rt_key(rt), 209 rt->rt_gateway, rt_mask(rt), 210 rt->rt_flags, 0); 211 } 212 } 213 214 struct rtqk_arg { 215 struct radix_node_head *rnh; 216 int draining; 217 int killed; 218 int found; 219 int updating; 220 time_t nextstop; 221 }; 222 223 /* 224 * Get rid of old routes. When draining, this deletes everything, even when 225 * the timeout is not expired yet. When updating, this makes sure that 226 * nothing has a timeout longer than the current value of rtq_reallyold. 227 */ 228 static int 229 in_rtqkill(struct radix_node *rn, void *rock) 230 { 231 struct rtqk_arg *ap = rock; 232 struct rtentry *rt = (struct rtentry *)rn; 233 int err; 234 235 if(rt->rt_flags & RTPRF_OURS) { 236 ap->found++; 237 238 if(ap->draining || rt->rt_rmx.rmx_expire <= time_second) { 239 if(rt->rt_refcnt > 0) 240 panic("rtqkill route really not free"); 241 242 err = rtrequest(RTM_DELETE, 243 (struct sockaddr *)rt_key(rt), 244 rt->rt_gateway, rt_mask(rt), 245 rt->rt_flags, 0); 246 if(err) { 247 log(LOG_WARNING, "in_rtqkill: error %d\n", err); 248 } else { 249 ap->killed++; 250 } 251 } else { 252 if(ap->updating 253 && (rt->rt_rmx.rmx_expire - time_second 254 > rtq_reallyold)) { 255 rt->rt_rmx.rmx_expire = time_second 256 + rtq_reallyold; 257 } 258 ap->nextstop = lmin(ap->nextstop, 259 rt->rt_rmx.rmx_expire); 260 } 261 } 262 263 return 0; 264 } 265 266 #define RTQ_TIMEOUT 60*10 /* run no less than once every ten minutes */ 267 static int rtq_timeout = RTQ_TIMEOUT; 268 269 static void 270 in_rtqtimo(void *rock) 271 { 272 struct radix_node_head *rnh = rock; 273 struct rtqk_arg arg; 274 struct timeval atv; 275 static time_t last_adjusted_timeout = 0; 276 int s; 277 278 arg.found = arg.killed = 0; 279 arg.rnh = rnh; 280 arg.nextstop = time_second + rtq_timeout; 281 arg.draining = arg.updating = 0; 282 s = splnet(); 283 rnh->rnh_walktree(rnh, in_rtqkill, &arg); 284 splx(s); 285 286 /* 287 * Attempt to be somewhat dynamic about this: 288 * If there are ``too many'' routes sitting around taking up space, 289 * then crank down the timeout, and see if we can't make some more 290 * go away. However, we make sure that we will never adjust more 291 * than once in rtq_timeout seconds, to keep from cranking down too 292 * hard. 293 */ 294 if((arg.found - arg.killed > rtq_toomany) 295 && (time_second - last_adjusted_timeout >= rtq_timeout) 296 && rtq_reallyold > rtq_minreallyold) { 297 rtq_reallyold = 2*rtq_reallyold / 3; 298 if(rtq_reallyold < rtq_minreallyold) { 299 rtq_reallyold = rtq_minreallyold; 300 } 301 302 last_adjusted_timeout = time_second; 303 #ifdef DIAGNOSTIC 304 log(LOG_DEBUG, "in_rtqtimo: adjusted rtq_reallyold to %d\n", 305 rtq_reallyold); 306 #endif 307 arg.found = arg.killed = 0; 308 arg.updating = 1; 309 s = splnet(); 310 rnh->rnh_walktree(rnh, in_rtqkill, &arg); 311 splx(s); 312 } 313 314 atv.tv_usec = 0; 315 atv.tv_sec = arg.nextstop - time_second; 316 timeout(in_rtqtimo, rock, tvtohz(&atv)); 317 } 318 319 void 320 in_rtqdrain(void) 321 { 322 struct radix_node_head *rnh = rt_tables[AF_INET]; 323 struct rtqk_arg arg; 324 int s; 325 arg.found = arg.killed = 0; 326 arg.rnh = rnh; 327 arg.nextstop = 0; 328 arg.draining = 1; 329 arg.updating = 0; 330 s = splnet(); 331 rnh->rnh_walktree(rnh, in_rtqkill, &arg); 332 splx(s); 333 } 334 335 /* 336 * Initialize our routing tree. 337 */ 338 int 339 in_inithead(void **head, int off) 340 { 341 struct radix_node_head *rnh; 342 343 if(!rn_inithead(head, off)) 344 return 0; 345 346 if(head != (void **)&rt_tables[AF_INET]) /* BOGUS! */ 347 return 1; /* only do this for the real routing table */ 348 349 rnh = *head; 350 rnh->rnh_addaddr = in_addroute; 351 rnh->rnh_matchaddr = in_matroute; 352 rnh->rnh_close = in_clsroute; 353 in_rtqtimo(rnh); /* kick off timeout first time */ 354 return 1; 355 } 356 357 358 /* 359 * This zaps old routes when the interface goes down. 360 * Currently it doesn't delete static routes; there are 361 * arguments one could make for both behaviors. For the moment, 362 * we will adopt the Principle of Least Surprise and leave them 363 * alone (with the knowledge that this will not be enough for some 364 * people). The ones we really want to get rid of are things like ARP 365 * entries, since the user might down the interface, walk over to a completely 366 * different network, and plug back in. 367 */ 368 struct in_ifadown_arg { 369 struct radix_node_head *rnh; 370 struct ifaddr *ifa; 371 }; 372 373 static int 374 in_ifadownkill(struct radix_node *rn, void *xap) 375 { 376 struct in_ifadown_arg *ap = xap; 377 struct rtentry *rt = (struct rtentry *)rn; 378 int err; 379 380 if (rt->rt_ifa == ap->ifa && !(rt->rt_flags & RTF_STATIC)) { 381 /* 382 * We need to disable the automatic prune that happens 383 * in this case in rtrequest() because it will blow 384 * away the pointers that rn_walktree() needs in order 385 * continue our descent. We will end up deleting all 386 * the routes that rtrequest() would have in any case, 387 * so that behavior is not needed there. 388 */ 389 rt->rt_flags &= ~RTF_PRCLONING; 390 err = rtrequest(RTM_DELETE, (struct sockaddr *)rt_key(rt), 391 rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0); 392 if (err) { 393 log(LOG_WARNING, "in_ifadownkill: error %d\n", err); 394 } 395 } 396 return 0; 397 } 398 399 int 400 in_ifadown(struct ifaddr *ifa) 401 { 402 struct in_ifadown_arg arg; 403 struct radix_node_head *rnh; 404 405 if (ifa->ifa_addr->sa_family != AF_INET) 406 return 1; 407 408 arg.rnh = rnh = rt_tables[AF_INET]; 409 arg.ifa = ifa; 410 rnh->rnh_walktree(rnh, in_ifadownkill, &arg); 411 ifa->ifa_flags &= ~IFA_ROUTE; 412 return 0; 413 } 414