1 /* $NetBSD: ip_flow.c,v 1.14 1999/10/17 23:38:45 sommerfeld Exp $ */ 2 3 /*- 4 * Copyright (c) 1998 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by the 3am Software Foundry ("3am"). It was developed by Matt Thomas. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/malloc.h> 42 #include <sys/mbuf.h> 43 #include <sys/domain.h> 44 #include <sys/protosw.h> 45 #include <sys/socket.h> 46 #include <sys/socketvar.h> 47 #include <sys/errno.h> 48 #include <sys/time.h> 49 #include <sys/kernel.h> 50 #include <sys/proc.h> 51 #include <sys/pool.h> 52 53 #include <vm/vm.h> 54 #include <sys/sysctl.h> 55 56 #include <net/if.h> 57 #include <net/if_dl.h> 58 #include <net/route.h> 59 #include <net/pfil.h> 60 61 #include <netinet/in.h> 62 #include <netinet/in_systm.h> 63 #include <netinet/ip.h> 64 #include <netinet/in_pcb.h> 65 #include <netinet/in_var.h> 66 #include <netinet/ip_var.h> 67 68 struct pool ipflow_pool; 69 70 LIST_HEAD(ipflowhead, ipflow); 71 72 #define IPFLOW_TIMER (5 * PR_SLOWHZ) 73 #define IPFLOW_HASHSIZE (1 << IPFLOW_HASHBITS) 74 75 static struct ipflowhead ipflowtable[IPFLOW_HASHSIZE]; 76 static struct ipflowhead ipflowlist; 77 static int ipflow_inuse; 78 79 #define IPFLOW_INSERT(bucket, ipf) \ 80 do { \ 81 LIST_INSERT_HEAD((bucket), (ipf), ipf_hash); \ 82 LIST_INSERT_HEAD(&ipflowlist, (ipf), ipf_list); \ 83 } while (0) 84 85 #define IPFLOW_REMOVE(ipf) \ 86 do { \ 87 LIST_REMOVE((ipf), ipf_hash); \ 88 LIST_REMOVE((ipf), ipf_list); \ 89 } while (0) 90 91 #ifndef IPFLOW_MAX 92 #define IPFLOW_MAX 256 93 #endif 94 int ip_maxflows = IPFLOW_MAX; 95 96 static unsigned 97 ipflow_hash( 98 struct in_addr dst, 99 struct in_addr src, 100 unsigned tos) 101 { 102 unsigned hash = tos; 103 int idx; 104 for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS) 105 hash += (dst.s_addr >> (32 - idx)) + (src.s_addr >> idx); 106 return hash & (IPFLOW_HASHSIZE-1); 107 } 108 109 static struct ipflow * 110 ipflow_lookup( 111 const struct ip *ip) 112 { 113 unsigned hash; 114 struct ipflow *ipf; 115 116 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos); 117 118 ipf = LIST_FIRST(&ipflowtable[hash]); 119 while (ipf != NULL) { 120 if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr 121 && ip->ip_src.s_addr == ipf->ipf_src.s_addr 122 && ip->ip_tos == ipf->ipf_tos) 123 break; 124 ipf = LIST_NEXT(ipf, ipf_hash); 125 } 126 return ipf; 127 } 128 129 void 130 ipflow_init() 131 { 132 int i; 133 134 pool_init(&ipflow_pool, sizeof(struct ipflow), 0, 0, 0, "ipflowpl", 135 0, NULL, NULL, M_IPFLOW); 136 137 LIST_INIT(&ipflowlist); 138 for (i = 0; i < IPFLOW_HASHSIZE; i++) 139 LIST_INIT(&ipflowtable[i]); 140 } 141 142 int 143 ipflow_fastforward( 144 struct mbuf *m) 145 { 146 struct ip *ip; 147 struct ipflow *ipf; 148 struct rtentry *rt; 149 int error; 150 int iplen; 151 152 /* 153 * Are we forwarding packets? Big enough for an IP packet? 154 */ 155 if (!ipforwarding || ipflow_inuse == 0 || m->m_len < sizeof(struct ip)) 156 return 0; 157 158 /* 159 * Was packet recieved as a link-level multicast or broadcast? 160 * If so, don't try to fast forward.. 161 */ 162 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0) 163 return 0; 164 165 /* 166 * IP header with no option and valid version and length 167 */ 168 ip = mtod(m, struct ip *); 169 iplen = ntohs(ip->ip_len); 170 if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) || 171 iplen < sizeof(struct ip) || iplen > m->m_pkthdr.len) 172 return 0; 173 /* 174 * Find a flow. 175 */ 176 if ((ipf = ipflow_lookup(ip)) == NULL) 177 return 0; 178 179 /* 180 * Veryify the IP header checksum. 181 */ 182 if (in_cksum(m, sizeof(struct ip)) != 0) 183 return 0; 184 185 /* 186 * Route and interface still up? 187 */ 188 rt = ipf->ipf_ro.ro_rt; 189 if ((rt->rt_flags & RTF_UP) == 0 || 190 (rt->rt_ifp->if_flags & IFF_UP) == 0) 191 return 0; 192 193 /* 194 * Packet size OK? TTL? 195 */ 196 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC) 197 return 0; 198 199 /* 200 * Everything checks out and so we can forward this packet. 201 * Modify the TTL and incrementally change the checksum. 202 * 203 * This method of adding the checksum works on either endian CPU. 204 * If htons() is inlined, all the arithmetic is folded; otherwise 205 * the htons()s are combined by CSE due to the __const__ attribute. 206 */ 207 ip->ip_ttl -= IPTTLDEC; 208 if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8)) 209 ip->ip_sum -= ~htons(IPTTLDEC << 8); 210 else 211 ip->ip_sum += htons(IPTTLDEC << 8); 212 213 /* 214 * Trim the packet in case it's too long.. 215 */ 216 if (m->m_pkthdr.len > iplen) { 217 if (m->m_len == m->m_pkthdr.len) { 218 m->m_len = iplen; 219 m->m_pkthdr.len = iplen; 220 } else 221 m_adj(m, iplen - m->m_pkthdr.len); 222 } 223 224 /* 225 * Send the packet on it's way. All we can get back is ENOBUFS 226 */ 227 ipf->ipf_uses++; 228 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER); 229 if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 230 &ipf->ipf_ro.ro_dst, rt)) != 0) { 231 if (error == ENOBUFS) 232 ipf->ipf_dropped++; 233 else 234 ipf->ipf_errors++; 235 } 236 return 1; 237 } 238 239 static void 240 ipflow_addstats( 241 struct ipflow *ipf) 242 { 243 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 244 ipstat.ips_cantforward += ipf->ipf_errors + ipf->ipf_dropped; 245 ipstat.ips_forward += ipf->ipf_uses; 246 ipstat.ips_fastforward += ipf->ipf_uses; 247 } 248 249 static void 250 ipflow_free( 251 struct ipflow *ipf) 252 { 253 int s; 254 /* 255 * Remove the flow from the hash table (at elevated IPL). 256 * Once it's off the list, we can deal with it at normal 257 * network IPL. 258 */ 259 s = splimp(); 260 IPFLOW_REMOVE(ipf); 261 splx(s); 262 ipflow_addstats(ipf); 263 RTFREE(ipf->ipf_ro.ro_rt); 264 ipflow_inuse--; 265 pool_put(&ipflow_pool, ipf); 266 } 267 268 struct ipflow * 269 ipflow_reap( 270 int just_one) 271 { 272 while (just_one || ipflow_inuse > ip_maxflows) { 273 struct ipflow *ipf, *maybe_ipf = NULL; 274 int s; 275 276 ipf = LIST_FIRST(&ipflowlist); 277 while (ipf != NULL) { 278 /* 279 * If this no longer points to a valid route 280 * reclaim it. 281 */ 282 if ((ipf->ipf_ro.ro_rt->rt_flags & RTF_UP) == 0) 283 goto done; 284 /* 285 * choose the one that's been least recently 286 * used or has had the least uses in the 287 * last 1.5 intervals. 288 */ 289 if (maybe_ipf == NULL || 290 ipf->ipf_timer < maybe_ipf->ipf_timer || 291 (ipf->ipf_timer == maybe_ipf->ipf_timer && 292 ipf->ipf_last_uses + ipf->ipf_uses < 293 maybe_ipf->ipf_last_uses + 294 maybe_ipf->ipf_uses)) 295 maybe_ipf = ipf; 296 ipf = LIST_NEXT(ipf, ipf_list); 297 } 298 ipf = maybe_ipf; 299 done: 300 /* 301 * Remove the entry from the flow table. 302 */ 303 s = splimp(); 304 IPFLOW_REMOVE(ipf); 305 splx(s); 306 ipflow_addstats(ipf); 307 RTFREE(ipf->ipf_ro.ro_rt); 308 if (just_one) 309 return ipf; 310 pool_put(&ipflow_pool, ipf); 311 ipflow_inuse--; 312 } 313 return NULL; 314 } 315 316 void 317 ipflow_slowtimo( 318 void) 319 { 320 struct ipflow *ipf, *next_ipf; 321 322 ipf = LIST_FIRST(&ipflowlist); 323 while (ipf != NULL) { 324 next_ipf = LIST_NEXT(ipf, ipf_list); 325 if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer)) { 326 ipflow_free(ipf); 327 } else { 328 ipf->ipf_last_uses = ipf->ipf_uses; 329 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 330 ipstat.ips_forward += ipf->ipf_uses; 331 ipstat.ips_fastforward += ipf->ipf_uses; 332 ipf->ipf_uses = 0; 333 } 334 ipf = next_ipf; 335 } 336 } 337 338 void 339 ipflow_create( 340 const struct route *ro, 341 struct mbuf *m) 342 { 343 const struct ip *const ip = mtod(m, struct ip *); 344 struct ipflow *ipf; 345 unsigned hash; 346 int s; 347 348 /* 349 * Don't create cache entries for ICMP messages. 350 */ 351 if (ip_maxflows == 0 || ip->ip_p == IPPROTO_ICMP) 352 return; 353 /* 354 * See if an existing flow struct exists. If so remove it from it's 355 * list and free the old route. If not, try to malloc a new one 356 * (if we aren't at our limit). 357 */ 358 ipf = ipflow_lookup(ip); 359 if (ipf == NULL) { 360 if (ipflow_inuse >= ip_maxflows) { 361 ipf = ipflow_reap(1); 362 } else { 363 ipf = pool_get(&ipflow_pool, PR_NOWAIT); 364 if (ipf == NULL) 365 return; 366 ipflow_inuse++; 367 } 368 bzero((caddr_t) ipf, sizeof(*ipf)); 369 } else { 370 s = splimp(); 371 IPFLOW_REMOVE(ipf); 372 splx(s); 373 ipflow_addstats(ipf); 374 RTFREE(ipf->ipf_ro.ro_rt); 375 ipf->ipf_uses = ipf->ipf_last_uses = 0; 376 ipf->ipf_errors = ipf->ipf_dropped = 0; 377 } 378 379 /* 380 * Fill in the updated information. 381 */ 382 ipf->ipf_ro = *ro; 383 ro->ro_rt->rt_refcnt++; 384 ipf->ipf_dst = ip->ip_dst; 385 ipf->ipf_src = ip->ip_src; 386 ipf->ipf_tos = ip->ip_tos; 387 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER); 388 ipf->ipf_start = time.tv_sec; 389 /* 390 * Insert into the approriate bucket of the flow table. 391 */ 392 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos); 393 s = splimp(); 394 IPFLOW_INSERT(&ipflowtable[hash], ipf); 395 splx(s); 396 } 397