ip_flow.c revision 1.20.2.1
1 /* $NetBSD: ip_flow.c,v 1.20.2.1 2001/11/12 21:19:23 thorpej 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/pool.h> 51 #include <sys/sysctl.h> 52 53 #include <net/if.h> 54 #include <net/if_dl.h> 55 #include <net/route.h> 56 #include <net/pfil.h> 57 58 #include <netinet/in.h> 59 #include <netinet/in_systm.h> 60 #include <netinet/ip.h> 61 #include <netinet/in_pcb.h> 62 #include <netinet/in_var.h> 63 #include <netinet/ip_var.h> 64 65 struct pool ipflow_pool; 66 67 LIST_HEAD(ipflowhead, ipflow); 68 69 #define IPFLOW_TIMER (5 * PR_SLOWHZ) 70 #define IPFLOW_HASHSIZE (1 << IPFLOW_HASHBITS) 71 72 static struct ipflowhead ipflowtable[IPFLOW_HASHSIZE]; 73 static struct ipflowhead ipflowlist; 74 static int ipflow_inuse; 75 76 #define IPFLOW_INSERT(bucket, ipf) \ 77 do { \ 78 LIST_INSERT_HEAD((bucket), (ipf), ipf_hash); \ 79 LIST_INSERT_HEAD(&ipflowlist, (ipf), ipf_list); \ 80 } while (0) 81 82 #define IPFLOW_REMOVE(ipf) \ 83 do { \ 84 LIST_REMOVE((ipf), ipf_hash); \ 85 LIST_REMOVE((ipf), ipf_list); \ 86 } while (0) 87 88 #ifndef IPFLOW_MAX 89 #define IPFLOW_MAX 256 90 #endif 91 int ip_maxflows = IPFLOW_MAX; 92 93 static unsigned 94 ipflow_hash( 95 struct in_addr dst, 96 struct in_addr src, 97 unsigned tos) 98 { 99 unsigned hash = tos; 100 int idx; 101 for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS) 102 hash += (dst.s_addr >> (32 - idx)) + (src.s_addr >> idx); 103 return hash & (IPFLOW_HASHSIZE-1); 104 } 105 106 static struct ipflow * 107 ipflow_lookup( 108 const struct ip *ip) 109 { 110 unsigned hash; 111 struct ipflow *ipf; 112 113 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos); 114 115 ipf = LIST_FIRST(&ipflowtable[hash]); 116 while (ipf != NULL) { 117 if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr 118 && ip->ip_src.s_addr == ipf->ipf_src.s_addr 119 && ip->ip_tos == ipf->ipf_tos) 120 break; 121 ipf = LIST_NEXT(ipf, ipf_hash); 122 } 123 return ipf; 124 } 125 126 void 127 ipflow_init() 128 { 129 int i; 130 131 pool_init(&ipflow_pool, sizeof(struct ipflow), 0, 0, 0, "ipflowpl", 132 0, NULL, NULL, M_IPFLOW); 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; 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 ip = mtod(m, struct ip *); 167 iplen = ntohs(ip->ip_len); 168 if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) || 169 iplen < sizeof(struct ip) || iplen > m->m_pkthdr.len) 170 return 0; 171 /* 172 * Find a flow. 173 */ 174 if ((ipf = ipflow_lookup(ip)) == NULL) 175 return 0; 176 177 /* 178 * Verify the IP header checksum. 179 */ 180 switch (m->m_pkthdr.csum_flags & 181 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_IPv4) | 182 M_CSUM_IPv4_BAD)) { 183 case M_CSUM_IPv4|M_CSUM_IPv4_BAD: 184 return (0); 185 186 case M_CSUM_IPv4: 187 /* Checksum was okay. */ 188 break; 189 190 default: 191 /* Must compute it ourselves. */ 192 if (in_cksum(m, sizeof(struct ip)) != 0) 193 return (0); 194 break; 195 } 196 197 /* 198 * Route and interface still up? 199 */ 200 rt = ipf->ipf_ro.ro_rt; 201 if ((rt->rt_flags & RTF_UP) == 0 || 202 (rt->rt_ifp->if_flags & IFF_UP) == 0) 203 return 0; 204 205 /* 206 * Packet size OK? TTL? 207 */ 208 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC) 209 return 0; 210 211 /* 212 * Clear any in-bound checksum flags for this packet. 213 */ 214 m->m_pkthdr.csum_flags = 0; 215 216 /* 217 * Everything checks out and so we can forward this packet. 218 * Modify the TTL and incrementally change the checksum. 219 * 220 * This method of adding the checksum works on either endian CPU. 221 * If htons() is inlined, all the arithmetic is folded; otherwise 222 * the htons()s are combined by CSE due to the __const__ attribute. 223 * 224 * Don't bother using HW checksumming here -- the incremental 225 * update is pretty fast. 226 */ 227 ip->ip_ttl -= IPTTLDEC; 228 if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8)) 229 ip->ip_sum -= ~htons(IPTTLDEC << 8); 230 else 231 ip->ip_sum += htons(IPTTLDEC << 8); 232 233 /* 234 * Trim the packet in case it's too long.. 235 */ 236 if (m->m_pkthdr.len > iplen) { 237 if (m->m_len == m->m_pkthdr.len) { 238 m->m_len = iplen; 239 m->m_pkthdr.len = iplen; 240 } else 241 m_adj(m, iplen - m->m_pkthdr.len); 242 } 243 244 /* 245 * Send the packet on it's way. All we can get back is ENOBUFS 246 */ 247 ipf->ipf_uses++; 248 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER); 249 250 if (rt->rt_flags & RTF_GATEWAY) 251 dst = rt->rt_gateway; 252 else 253 dst = &ipf->ipf_ro.ro_dst; 254 255 if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, dst, rt)) != 0) { 256 if (error == ENOBUFS) 257 ipf->ipf_dropped++; 258 else 259 ipf->ipf_errors++; 260 } 261 return 1; 262 } 263 264 static void 266 ipflow_addstats( 267 struct ipflow *ipf) 268 { 269 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 270 ipstat.ips_cantforward += ipf->ipf_errors + ipf->ipf_dropped; 271 ipstat.ips_forward += ipf->ipf_uses; 272 ipstat.ips_fastforward += ipf->ipf_uses; 273 } 274 275 static void 276 ipflow_free( 277 struct ipflow *ipf) 278 { 279 int s; 280 /* 281 * Remove the flow from the hash table (at elevated IPL). 282 * Once it's off the list, we can deal with it at normal 283 * network IPL. 284 */ 285 s = splnet(); 286 IPFLOW_REMOVE(ipf); 287 splx(s); 288 ipflow_addstats(ipf); 289 RTFREE(ipf->ipf_ro.ro_rt); 290 ipflow_inuse--; 291 pool_put(&ipflow_pool, ipf); 292 } 293 294 struct ipflow * 295 ipflow_reap( 296 int just_one) 297 { 298 while (just_one || ipflow_inuse > ip_maxflows) { 299 struct ipflow *ipf, *maybe_ipf = NULL; 300 int s; 301 302 ipf = LIST_FIRST(&ipflowlist); 303 while (ipf != NULL) { 304 /* 305 * If this no longer points to a valid route 306 * reclaim it. 307 */ 308 if ((ipf->ipf_ro.ro_rt->rt_flags & RTF_UP) == 0) 309 goto done; 310 /* 311 * choose the one that's been least recently 312 * used or has had the least uses in the 313 * last 1.5 intervals. 314 */ 315 if (maybe_ipf == NULL || 316 ipf->ipf_timer < maybe_ipf->ipf_timer || 317 (ipf->ipf_timer == maybe_ipf->ipf_timer && 318 ipf->ipf_last_uses + ipf->ipf_uses < 319 maybe_ipf->ipf_last_uses + 320 maybe_ipf->ipf_uses)) 321 maybe_ipf = ipf; 322 ipf = LIST_NEXT(ipf, ipf_list); 323 } 324 ipf = maybe_ipf; 325 done: 326 /* 327 * Remove the entry from the flow table. 328 */ 329 s = splnet(); 330 IPFLOW_REMOVE(ipf); 331 splx(s); 332 ipflow_addstats(ipf); 333 RTFREE(ipf->ipf_ro.ro_rt); 334 if (just_one) 335 return ipf; 336 pool_put(&ipflow_pool, ipf); 337 ipflow_inuse--; 338 } 339 return NULL; 340 } 341 342 void 343 ipflow_slowtimo( 344 void) 345 { 346 struct ipflow *ipf, *next_ipf; 347 348 ipf = LIST_FIRST(&ipflowlist); 349 while (ipf != NULL) { 350 next_ipf = LIST_NEXT(ipf, ipf_list); 351 if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer)) { 352 ipflow_free(ipf); 353 } else { 354 ipf->ipf_last_uses = ipf->ipf_uses; 355 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 356 ipstat.ips_forward += ipf->ipf_uses; 357 ipstat.ips_fastforward += ipf->ipf_uses; 358 ipf->ipf_uses = 0; 359 } 360 ipf = next_ipf; 361 } 362 } 363 364 void 365 ipflow_create( 366 const struct route *ro, 367 struct mbuf *m) 368 { 369 const struct ip *const ip = mtod(m, struct ip *); 370 struct ipflow *ipf; 371 unsigned hash; 372 int s; 373 374 /* 375 * Don't create cache entries for ICMP messages. 376 */ 377 if (ip_maxflows == 0 || ip->ip_p == IPPROTO_ICMP) 378 return; 379 /* 380 * See if an existing flow struct exists. If so remove it from it's 381 * list and free the old route. If not, try to malloc a new one 382 * (if we aren't at our limit). 383 */ 384 ipf = ipflow_lookup(ip); 385 if (ipf == NULL) { 386 if (ipflow_inuse >= ip_maxflows) { 387 ipf = ipflow_reap(1); 388 } else { 389 ipf = pool_get(&ipflow_pool, PR_NOWAIT); 390 if (ipf == NULL) 391 return; 392 ipflow_inuse++; 393 } 394 bzero((caddr_t) ipf, sizeof(*ipf)); 395 } else { 396 s = splnet(); 397 IPFLOW_REMOVE(ipf); 398 splx(s); 399 ipflow_addstats(ipf); 400 RTFREE(ipf->ipf_ro.ro_rt); 401 ipf->ipf_uses = ipf->ipf_last_uses = 0; 402 ipf->ipf_errors = ipf->ipf_dropped = 0; 403 } 404 405 /* 406 * Fill in the updated information. 407 */ 408 ipf->ipf_ro = *ro; 409 ro->ro_rt->rt_refcnt++; 410 ipf->ipf_dst = ip->ip_dst; 411 ipf->ipf_src = ip->ip_src; 412 ipf->ipf_tos = ip->ip_tos; 413 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER); 414 ipf->ipf_start = time.tv_sec; 415 /* 416 * Insert into the approriate bucket of the flow table. 417 */ 418 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos); 419 s = splnet(); 420 IPFLOW_INSERT(&ipflowtable[hash], ipf); 421 splx(s); 422 } 423
Indexes created Tue Oct 14 21:09:58 GMT 2025