ip_flow.c revision 1.28
1 /* $NetBSD: ip_flow.c,v 1.28 2004/04/25 16:42:42 simonb 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/cdefs.h> 40 __KERNEL_RCSID(0, "$NetBSD: ip_flow.c,v 1.28 2004/04/25 16:42:42 simonb Exp $"); 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/malloc.h> 45 #include <sys/mbuf.h> 46 #include <sys/domain.h> 47 #include <sys/protosw.h> 48 #include <sys/socket.h> 49 #include <sys/socketvar.h> 50 #include <sys/errno.h> 51 #include <sys/time.h> 52 #include <sys/kernel.h> 53 #include <sys/pool.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 POOL_INIT(ipflow_pool, sizeof(struct ipflow), 0, 0, 0, "ipflowpl", NULL); 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 (/*CONSTCOND*/ 0) 84 85 #define IPFLOW_REMOVE(ipf) \ 86 do { \ 87 LIST_REMOVE((ipf), ipf_hash); \ 88 LIST_REMOVE((ipf), ipf_list); \ 89 } while (/*CONSTCOND*/ 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 LIST_INIT(&ipflowlist); 135 for (i = 0; i < IPFLOW_HASHSIZE; i++) 136 LIST_INIT(&ipflowtable[i]); 137 } 138 139 int 140 ipflow_fastforward( 141 struct mbuf *m) 142 { 143 struct ip *ip, ip_store; 144 struct ipflow *ipf; 145 struct rtentry *rt; 146 struct sockaddr *dst; 147 int error; 148 int iplen; 149 150 /* 151 * Are we forwarding packets? Big enough for an IP packet? 152 */ 153 if (!ipforwarding || ipflow_inuse == 0 || m->m_len < sizeof(struct ip)) 154 return 0; 155 156 /* 157 * Was packet received as a link-level multicast or broadcast? 158 * If so, don't try to fast forward.. 159 */ 160 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0) 161 return 0; 162 163 /* 164 * IP header with no option and valid version and length 165 */ 166 if (IP_HDR_ALIGNED_P(mtod(m, caddr_t))) 167 ip = mtod(m, struct ip *); 168 else { 169 memcpy(&ip_store, mtod(m, caddr_t), sizeof(ip_store)); 170 ip = &ip_store; 171 } 172 iplen = ntohs(ip->ip_len); 173 if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) || 174 iplen < sizeof(struct ip) || iplen > m->m_pkthdr.len) 175 return 0; 176 /* 177 * Find a flow. 178 */ 179 if ((ipf = ipflow_lookup(ip)) == NULL) 180 return 0; 181 182 /* 183 * Verify the IP header checksum. 184 */ 185 switch (m->m_pkthdr.csum_flags & 186 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_IPv4) | 187 M_CSUM_IPv4_BAD)) { 188 case M_CSUM_IPv4|M_CSUM_IPv4_BAD: 189 return (0); 190 191 case M_CSUM_IPv4: 192 /* Checksum was okay. */ 193 break; 194 195 default: 196 /* Must compute it ourselves. */ 197 if (in_cksum(m, sizeof(struct ip)) != 0) 198 return (0); 199 break; 200 } 201 202 /* 203 * Route and interface still up? 204 */ 205 rt = ipf->ipf_ro.ro_rt; 206 if ((rt->rt_flags & RTF_UP) == 0 || 207 (rt->rt_ifp->if_flags & IFF_UP) == 0) 208 return 0; 209 210 /* 211 * Packet size OK? TTL? 212 */ 213 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC) 214 return 0; 215 216 /* 217 * Clear any in-bound checksum flags for this packet. 218 */ 219 m->m_pkthdr.csum_flags = 0; 220 221 /* 222 * Everything checks out and so we can forward this packet. 223 * Modify the TTL and incrementally change the checksum. 224 * 225 * This method of adding the checksum works on either endian CPU. 226 * If htons() is inlined, all the arithmetic is folded; otherwise 227 * the htons()s are combined by CSE due to the __const__ attribute. 228 * 229 * Don't bother using HW checksumming here -- the incremental 230 * update is pretty fast. 231 */ 232 ip->ip_ttl -= IPTTLDEC; 233 if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8)) 234 ip->ip_sum -= ~htons(IPTTLDEC << 8); 235 else 236 ip->ip_sum += htons(IPTTLDEC << 8); 237 238 /* 239 * Done modifying the header; copy it back, if necessary. 240 */ 241 if (IP_HDR_ALIGNED_P(mtod(m, caddr_t)) == 0) 242 memcpy(mtod(m, caddr_t), &ip_store, sizeof(ip_store)); 243 244 /* 245 * Trim the packet in case it's too long.. 246 */ 247 if (m->m_pkthdr.len > iplen) { 248 if (m->m_len == m->m_pkthdr.len) { 249 m->m_len = iplen; 250 m->m_pkthdr.len = iplen; 251 } else 252 m_adj(m, iplen - m->m_pkthdr.len); 253 } 254 255 /* 256 * Send the packet on it's way. All we can get back is ENOBUFS 257 */ 258 ipf->ipf_uses++; 259 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER); 260 261 if (rt->rt_flags & RTF_GATEWAY) 262 dst = rt->rt_gateway; 263 else 264 dst = &ipf->ipf_ro.ro_dst; 265 266 if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, dst, rt)) != 0) { 267 if (error == ENOBUFS) 268 ipf->ipf_dropped++; 269 else 270 ipf->ipf_errors++; 271 } 272 return 1; 273 } 274 275 static void 277 ipflow_addstats( 278 struct ipflow *ipf) 279 { 280 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 281 ipstat.ips_cantforward += ipf->ipf_errors + ipf->ipf_dropped; 282 ipstat.ips_forward += ipf->ipf_uses; 283 ipstat.ips_fastforward += ipf->ipf_uses; 284 } 285 286 static void 287 ipflow_free( 288 struct ipflow *ipf) 289 { 290 int s; 291 /* 292 * Remove the flow from the hash table (at elevated IPL). 293 * Once it's off the list, we can deal with it at normal 294 * network IPL. 295 */ 296 s = splnet(); 297 IPFLOW_REMOVE(ipf); 298 splx(s); 299 ipflow_addstats(ipf); 300 RTFREE(ipf->ipf_ro.ro_rt); 301 ipflow_inuse--; 302 pool_put(&ipflow_pool, ipf); 303 } 304 305 struct ipflow * 306 ipflow_reap( 307 int just_one) 308 { 309 while (just_one || ipflow_inuse > ip_maxflows) { 310 struct ipflow *ipf, *maybe_ipf = NULL; 311 int s; 312 313 ipf = LIST_FIRST(&ipflowlist); 314 while (ipf != NULL) { 315 /* 316 * If this no longer points to a valid route 317 * reclaim it. 318 */ 319 if ((ipf->ipf_ro.ro_rt->rt_flags & RTF_UP) == 0) 320 goto done; 321 /* 322 * choose the one that's been least recently 323 * used or has had the least uses in the 324 * last 1.5 intervals. 325 */ 326 if (maybe_ipf == NULL || 327 ipf->ipf_timer < maybe_ipf->ipf_timer || 328 (ipf->ipf_timer == maybe_ipf->ipf_timer && 329 ipf->ipf_last_uses + ipf->ipf_uses < 330 maybe_ipf->ipf_last_uses + 331 maybe_ipf->ipf_uses)) 332 maybe_ipf = ipf; 333 ipf = LIST_NEXT(ipf, ipf_list); 334 } 335 ipf = maybe_ipf; 336 done: 337 /* 338 * Remove the entry from the flow table. 339 */ 340 s = splnet(); 341 IPFLOW_REMOVE(ipf); 342 splx(s); 343 ipflow_addstats(ipf); 344 RTFREE(ipf->ipf_ro.ro_rt); 345 if (just_one) 346 return ipf; 347 pool_put(&ipflow_pool, ipf); 348 ipflow_inuse--; 349 } 350 return NULL; 351 } 352 353 void 354 ipflow_slowtimo( 355 void) 356 { 357 struct ipflow *ipf, *next_ipf; 358 359 ipf = LIST_FIRST(&ipflowlist); 360 while (ipf != NULL) { 361 next_ipf = LIST_NEXT(ipf, ipf_list); 362 if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer)) { 363 ipflow_free(ipf); 364 } else { 365 ipf->ipf_last_uses = ipf->ipf_uses; 366 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 367 ipstat.ips_forward += ipf->ipf_uses; 368 ipstat.ips_fastforward += ipf->ipf_uses; 369 ipf->ipf_uses = 0; 370 } 371 ipf = next_ipf; 372 } 373 } 374 375 void 376 ipflow_create( 377 const struct route *ro, 378 struct mbuf *m) 379 { 380 const struct ip *const ip = mtod(m, struct ip *); 381 struct ipflow *ipf; 382 unsigned hash; 383 int s; 384 385 /* 386 * Don't create cache entries for ICMP messages. 387 */ 388 if (ip_maxflows == 0 || ip->ip_p == IPPROTO_ICMP) 389 return; 390 /* 391 * See if an existing flow struct exists. If so remove it from it's 392 * list and free the old route. If not, try to malloc a new one 393 * (if we aren't at our limit). 394 */ 395 ipf = ipflow_lookup(ip); 396 if (ipf == NULL) { 397 if (ipflow_inuse >= ip_maxflows) { 398 ipf = ipflow_reap(1); 399 } else { 400 ipf = pool_get(&ipflow_pool, PR_NOWAIT); 401 if (ipf == NULL) 402 return; 403 ipflow_inuse++; 404 } 405 bzero((caddr_t) ipf, sizeof(*ipf)); 406 } else { 407 s = splnet(); 408 IPFLOW_REMOVE(ipf); 409 splx(s); 410 ipflow_addstats(ipf); 411 RTFREE(ipf->ipf_ro.ro_rt); 412 ipf->ipf_uses = ipf->ipf_last_uses = 0; 413 ipf->ipf_errors = ipf->ipf_dropped = 0; 414 } 415 416 /* 417 * Fill in the updated information. 418 */ 419 ipf->ipf_ro = *ro; 420 ro->ro_rt->rt_refcnt++; 421 ipf->ipf_dst = ip->ip_dst; 422 ipf->ipf_src = ip->ip_src; 423 ipf->ipf_tos = ip->ip_tos; 424 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER); 425 ipf->ipf_start = time.tv_sec; 426 /* 427 * Insert into the approriate bucket of the flow table. 428 */ 429 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos); 430 s = splnet(); 431 IPFLOW_INSERT(&ipflowtable[hash], ipf); 432 splx(s); 433 } 434 435 void 436 ipflow_invalidate_all( 437 void) 438 { 439 struct ipflow *ipf, *next_ipf; 440 int s; 441 442 s = splnet(); 443 ipf = LIST_FIRST(&ipflowlist); 444 for (ipf = LIST_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) { 445 next_ipf = LIST_NEXT(ipf, ipf_list); 446 ipflow_free(ipf); 447 } 448 splx(s); 449 } 450
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