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 1.15 1995/07/10 15:39:10 wollman 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/queue.h> 49 #include <sys/socket.h> 50 #include <sys/socketvar.h> 51 #include <sys/mbuf.h> 52 #include <sys/syslog.h> 53 54 #include <net/if.h> 55 #include <net/route.h> 56 #include <netinet/in.h> 57 #include <netinet/in_systm.h> 58 #include <netinet/in_var.h> 59 60 #include <netinet/ip.h> 61 #include <netinet/ip_var.h> 62 63 #include <netinet/tcp.h> 64 #include <netinet/tcp_seq.h> 65 #include <netinet/tcp_timer.h> 66 #include <netinet/tcp_var.h> 67 #ifndef MTUDISC 68 #include <netinet/tcpip.h> 69 #endif /* not MTUDISC */ 70 71 #define RTPRF_OURS RTF_PROTO3 /* set on routes we manage */ 72 73 /* 74 * Do what we need to do when inserting a route. 75 */ 76 static struct radix_node * 77 in_addroute(void *v_arg, void *n_arg, struct radix_node_head *head, 78 struct radix_node *treenodes) 79 { 80 struct rtentry *rt = (struct rtentry *)treenodes; 81 struct sockaddr_in *sin = (struct sockaddr_in *)rt_key(rt); 82 83 /* 84 * For IP, all unicast non-host routes are automatically cloning. 85 */ 86 if(!(rt->rt_flags & (RTF_HOST | RTF_CLONING))) { 87 if(!IN_MULTICAST(ntohl(sin->sin_addr.s_addr))) { 88 rt->rt_flags |= RTF_PRCLONING; 89 } 90 } 91 92 /* 93 * We also specify a send and receive pipe size for every 94 * route added, to help TCP a bit. TCP doesn't actually 95 * want a true pipe size, which would be prohibitive in memory 96 * costs and is hard to compute anyway; it simply uses these 97 * values to size its buffers. So, we fill them in with the 98 * same values that TCP would have used anyway, and allow the 99 * installing program or the link layer to override these values 100 * as it sees fit. This will hopefully allow TCP more 101 * opportunities to save its ssthresh value. 102 */ 103 if (!rt->rt_rmx.rmx_sendpipe && !(rt->rt_rmx.rmx_locks & RTV_SPIPE)) 104 rt->rt_rmx.rmx_sendpipe = tcp_sendspace; 105 106 if (!rt->rt_rmx.rmx_recvpipe && !(rt->rt_rmx.rmx_locks & RTV_RPIPE)) 107 rt->rt_rmx.rmx_recvpipe = tcp_recvspace; 108 109 #ifndef MTUDISC 110 /* 111 * Finally, set an MTU, again duplicating logic in TCP. 112 * The in_localaddr() business will go away when we have 113 * proper PMTU discovery. 114 */ 115 #endif /* not MTUDISC */ 116 if (!rt->rt_rmx.rmx_mtu && !(rt->rt_rmx.rmx_locks & RTV_MTU) 117 && rt->rt_ifp) 118 #ifndef MTUDISC 119 rt->rt_rmx.rmx_mtu = (in_localaddr(sin->sin_addr) 120 ? rt->rt_ifp->if_mtu 121 : tcp_mssdflt + sizeof(struct tcpiphdr)); 122 #else /* MTUDISC */ 123 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu; 124 #endif /* MTUDISC */ 125 126 return rn_addroute(v_arg, n_arg, head, treenodes); 127 } 128 129 /* 130 * This code is the inverse of in_clsroute: on first reference, if we 131 * were managing the route, stop doing so and set the expiration timer 132 * back off again. 133 */ 134 static struct radix_node * 135 in_matroute(void *v_arg, struct radix_node_head *head) 136 { 137 struct radix_node *rn = rn_match(v_arg, head); 138 struct rtentry *rt = (struct rtentry *)rn; 139 140 if(rt && rt->rt_refcnt == 0) { /* this is first reference */ 141 if(rt->rt_flags & RTPRF_OURS) { 142 rt->rt_flags &= ~RTPRF_OURS; 143 rt->rt_rmx.rmx_expire = 0; 144 } 145 } 146 return rn; 147 } 148 149 /* MIB variables: net.inet.ip.{rtexpire,rtmaxcache,rtminexpire}. */ 150 int rtq_reallyold = 60*60; /* one hour is ``really old'' */ 151 int rtq_toomany = 128; /* 128 cached routes is ``too many'' */ 152 int rtq_minreallyold = 10; /* never automatically crank down to less */ 153 154 /* 155 * On last reference drop, mark the route as belong to us so that it can be 156 * timed out. 157 */ 158 static void 159 in_clsroute(struct radix_node *rn, struct radix_node_head *head) 160 { 161 struct rtentry *rt = (struct rtentry *)rn; 162 163 if(!(rt->rt_flags & RTF_UP)) 164 return; /* prophylactic measures */ 165 166 if((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST) 167 return; 168 169 if((rt->rt_flags & (RTF_WASCLONED | RTPRF_OURS)) 170 != RTF_WASCLONED) 171 return; 172 173 /* 174 * As requested by David Greenman: 175 * If rtq_reallyold is 0, just delete the route without 176 * waiting for a timeout cycle to kill it. 177 */ 178 if(rtq_reallyold != 0) { 179 rt->rt_flags |= RTPRF_OURS; 180 rt->rt_rmx.rmx_expire = time.tv_sec + rtq_reallyold; 181 } else { 182 rtrequest(RTM_DELETE, 183 (struct sockaddr *)rt_key(rt), 184 rt->rt_gateway, rt_mask(rt), 185 rt->rt_flags, 0); 186 } 187 } 188 189 struct rtqk_arg { 190 struct radix_node_head *rnh; 191 int draining; 192 int killed; 193 int found; 194 int updating; 195 time_t nextstop; 196 }; 197 198 /* 199 * Get rid of old routes. When draining, this deletes everything, even when 200 * the timeout is not expired yet. When updating, this makes sure that 201 * nothing has a timeout longer than the current value of rtq_reallyold. 202 */ 203 static int 204 in_rtqkill(struct radix_node *rn, void *rock) 205 { 206 struct rtqk_arg *ap = rock; 207 struct radix_node_head *rnh = ap->rnh; 208 struct rtentry *rt = (struct rtentry *)rn; 209 int err; 210 211 if(rt->rt_flags & RTPRF_OURS) { 212 ap->found++; 213 214 if(ap->draining || rt->rt_rmx.rmx_expire <= time.tv_sec) { 215 if(rt->rt_refcnt > 0) 216 panic("rtqkill route really not free"); 217 218 err = rtrequest(RTM_DELETE, 219 (struct sockaddr *)rt_key(rt), 220 rt->rt_gateway, rt_mask(rt), 221 rt->rt_flags, 0); 222 if(err) { 223 log(LOG_WARNING, "in_rtqkill: error %d\n", err); 224 } else { 225 ap->killed++; 226 } 227 } else { 228 if(ap->updating 229 && (rt->rt_rmx.rmx_expire - time.tv_sec 230 > rtq_reallyold)) { 231 rt->rt_rmx.rmx_expire = time.tv_sec 232 + rtq_reallyold; 233 } 234 ap->nextstop = lmin(ap->nextstop, 235 rt->rt_rmx.rmx_expire); 236 } 237 } 238 239 return 0; 240 } 241 242 #define RTQ_TIMEOUT 60*10 /* run no less than once every ten minutes */ 243 int rtq_timeout = RTQ_TIMEOUT; 244 245 static void 246 in_rtqtimo(void *rock) 247 { 248 struct radix_node_head *rnh = rock; 249 struct rtqk_arg arg; 250 struct timeval atv; 251 static time_t last_adjusted_timeout = 0; 252 int s; 253 254 arg.found = arg.killed = 0; 255 arg.rnh = rnh; 256 arg.nextstop = time.tv_sec + rtq_timeout; 257 arg.draining = arg.updating = 0; 258 s = splnet(); 259 rnh->rnh_walktree(rnh, in_rtqkill, &arg); 260 splx(s); 261 262 /* 263 * Attempt to be somewhat dynamic about this: 264 * If there are ``too many'' routes sitting around taking up space, 265 * then crank down the timeout, and see if we can't make some more 266 * go away. However, we make sure that we will never adjust more 267 * than once in rtq_timeout seconds, to keep from cranking down too 268 * hard. 269 */ 270 if((arg.found - arg.killed > rtq_toomany) 271 && (time.tv_sec - last_adjusted_timeout >= rtq_timeout) 272 && rtq_reallyold > rtq_minreallyold) { 273 rtq_reallyold = 2*rtq_reallyold / 3; 274 if(rtq_reallyold < rtq_minreallyold) { 275 rtq_reallyold = rtq_minreallyold; 276 } 277 278 last_adjusted_timeout = time.tv_sec; 279 log(LOG_DEBUG, "in_rtqtimo: adjusted rtq_reallyold to %d\n", 280 rtq_reallyold); 281 arg.found = arg.killed = 0; 282 arg.updating = 1; 283 s = splnet(); 284 rnh->rnh_walktree(rnh, in_rtqkill, &arg); 285 splx(s); 286 } 287 288 atv.tv_usec = 0; 289 atv.tv_sec = arg.nextstop; 290 timeout(in_rtqtimo, rock, hzto(&atv)); 291 } 292 293 void 294 in_rtqdrain(void) 295 { 296 struct radix_node_head *rnh = rt_tables[AF_INET]; 297 struct rtqk_arg arg; 298 int s; 299 arg.found = arg.killed = 0; 300 arg.rnh = rnh; 301 arg.nextstop = 0; 302 arg.draining = 1; 303 arg.updating = 0; 304 s = splnet(); 305 rnh->rnh_walktree(rnh, in_rtqkill, &arg); 306 splx(s); 307 } 308 309 /* 310 * Initialize our routing tree. 311 */ 312 int 313 in_inithead(void **head, int off) 314 { 315 struct radix_node_head *rnh; 316 317 if(!rn_inithead(head, off)) 318 return 0; 319 320 if(head != (void **)&rt_tables[AF_INET]) /* BOGUS! */ 321 return 1; /* only do this for the real routing table */ 322 323 rnh = *head; 324 rnh->rnh_addaddr = in_addroute; 325 rnh->rnh_matchaddr = in_matroute; 326 rnh->rnh_close = in_clsroute; 327 in_rtqtimo(rnh); /* kick off timeout first time */ 328 return 1; 329 } 330 331