ip_flow.c revision 1.18
1 /* $NetBSD: ip_flow.c,v 1.18 2001/06/02 16:17:09 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/proc.h> 51 #include <sys/pool.h> 52 53 #include <uvm/uvm_extern.h> 54 55 #include <sys/sysctl.h> 56 57 #include <net/if.h> 58 #include <net/if_dl.h> 59 #include <net/route.h> 60 #include <net/pfil.h> 61 62 #include <netinet/in.h> 63 #include <netinet/in_systm.h> 64 #include <netinet/ip.h> 65 #include <netinet/in_pcb.h> 66 #include <netinet/in_var.h> 67 #include <netinet/ip_var.h> 68 69 struct pool ipflow_pool; 70 71 LIST_HEAD(ipflowhead, ipflow); 72 73 #define IPFLOW_TIMER (5 * PR_SLOWHZ) 74 #define IPFLOW_HASHSIZE (1 << IPFLOW_HASHBITS) 75 76 static struct ipflowhead ipflowtable[IPFLOW_HASHSIZE]; 77 static struct ipflowhead ipflowlist; 78 static int ipflow_inuse; 79 80 #define IPFLOW_INSERT(bucket, ipf) \ 81 do { \ 82 LIST_INSERT_HEAD((bucket), (ipf), ipf_hash); \ 83 LIST_INSERT_HEAD(&ipflowlist, (ipf), ipf_list); \ 84 } while (0) 85 86 #define IPFLOW_REMOVE(ipf) \ 87 do { \ 88 LIST_REMOVE((ipf), ipf_hash); \ 89 LIST_REMOVE((ipf), ipf_list); \ 90 } while (0) 91 92 #ifndef IPFLOW_MAX 93 #define IPFLOW_MAX 256 94 #endif 95 int ip_maxflows = IPFLOW_MAX; 96 97 static unsigned 98 ipflow_hash( 99 struct in_addr dst, 100 struct in_addr src, 101 unsigned tos) 102 { 103 unsigned hash = tos; 104 int idx; 105 for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS) 106 hash += (dst.s_addr >> (32 - idx)) + (src.s_addr >> idx); 107 return hash & (IPFLOW_HASHSIZE-1); 108 } 109 110 static struct ipflow * 111 ipflow_lookup( 112 const struct ip *ip) 113 { 114 unsigned hash; 115 struct ipflow *ipf; 116 117 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos); 118 119 ipf = LIST_FIRST(&ipflowtable[hash]); 120 while (ipf != NULL) { 121 if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr 122 && ip->ip_src.s_addr == ipf->ipf_src.s_addr 123 && ip->ip_tos == ipf->ipf_tos) 124 break; 125 ipf = LIST_NEXT(ipf, ipf_hash); 126 } 127 return ipf; 128 } 129 130 void 131 ipflow_init() 132 { 133 int i; 134 135 pool_init(&ipflow_pool, sizeof(struct ipflow), 0, 0, 0, "ipflowpl", 136 0, NULL, NULL, M_IPFLOW); 137 138 LIST_INIT(&ipflowlist); 139 for (i = 0; i < IPFLOW_HASHSIZE; i++) 140 LIST_INIT(&ipflowtable[i]); 141 } 142 143 int 144 ipflow_fastforward( 145 struct mbuf *m) 146 { 147 struct ip *ip; 148 struct ipflow *ipf; 149 struct rtentry *rt; 150 struct sockaddr *dst; 151 int error; 152 int iplen; 153 154 /* 155 * Are we forwarding packets? Big enough for an IP packet? 156 */ 157 if (!ipforwarding || ipflow_inuse == 0 || m->m_len < sizeof(struct ip)) 158 return 0; 159 160 /* 161 * Was packet recieved as a link-level multicast or broadcast? 162 * If so, don't try to fast forward.. 163 */ 164 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0) 165 return 0; 166 167 /* 168 * IP header with no option and valid version and length 169 */ 170 ip = mtod(m, struct ip *); 171 iplen = ntohs(ip->ip_len); 172 if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) || 173 iplen < sizeof(struct ip) || iplen > m->m_pkthdr.len) 174 return 0; 175 /* 176 * Find a flow. 177 */ 178 if ((ipf = ipflow_lookup(ip)) == NULL) 179 return 0; 180 181 /* 182 * Verify the IP header checksum. 183 */ 184 switch (m->m_pkthdr.csum_flags & 185 ((m->m_pkthdr.rcvif->if_csum_flags & M_CSUM_IPv4) | 186 M_CSUM_IPv4_BAD)) { 187 case M_CSUM_IPv4|M_CSUM_IPv4_BAD: 188 return (0); 189 190 case M_CSUM_IPv4: 191 /* Checksum was okay. */ 192 break; 193 194 default: 195 /* Must compute it ourselves. */ 196 if (in_cksum(m, sizeof(struct ip)) != 0) 197 return (0); 198 break; 199 } 200 201 /* 202 * Route and interface still up? 203 */ 204 rt = ipf->ipf_ro.ro_rt; 205 if ((rt->rt_flags & RTF_UP) == 0 || 206 (rt->rt_ifp->if_flags & IFF_UP) == 0) 207 return 0; 208 209 /* 210 * Packet size OK? TTL? 211 */ 212 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC) 213 return 0; 214 215 /* 216 * Clear any in-bound checksum flags for this packet. 217 */ 218 m->m_pkthdr.csum_flags = 0; 219 220 /* 221 * Everything checks out and so we can forward this packet. 222 * Modify the TTL and incrementally change the checksum. 223 * 224 * This method of adding the checksum works on either endian CPU. 225 * If htons() is inlined, all the arithmetic is folded; otherwise 226 * the htons()s are combined by CSE due to the __const__ attribute. 227 * 228 * Don't bother using HW checksumming here -- the incremental 229 * update is pretty fast. 230 */ 231 ip->ip_ttl -= IPTTLDEC; 232 if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8)) 233 ip->ip_sum -= ~htons(IPTTLDEC << 8); 234 else 235 ip->ip_sum += htons(IPTTLDEC << 8); 236 237 /* 238 * Trim the packet in case it's too long.. 239 */ 240 if (m->m_pkthdr.len > iplen) { 241 if (m->m_len == m->m_pkthdr.len) { 242 m->m_len = iplen; 243 m->m_pkthdr.len = iplen; 244 } else 245 m_adj(m, iplen - m->m_pkthdr.len); 246 } 247 248 /* 249 * Send the packet on it's way. All we can get back is ENOBUFS 250 */ 251 ipf->ipf_uses++; 252 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER); 253 254 if (rt->rt_flags & RTF_GATEWAY) 255 dst = rt->rt_gateway; 256 else 257 dst = &ipf->ipf_ro.ro_dst; 258 259 if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, dst, rt)) != 0) { 260 if (error == ENOBUFS) 261 ipf->ipf_dropped++; 262 else 263 ipf->ipf_errors++; 264 } 265 return 1; 266 } 267 268 static void 270 ipflow_addstats( 271 struct ipflow *ipf) 272 { 273 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 274 ipstat.ips_cantforward += ipf->ipf_errors + ipf->ipf_dropped; 275 ipstat.ips_forward += ipf->ipf_uses; 276 ipstat.ips_fastforward += ipf->ipf_uses; 277 } 278 279 static void 280 ipflow_free( 281 struct ipflow *ipf) 282 { 283 int s; 284 /* 285 * Remove the flow from the hash table (at elevated IPL). 286 * Once it's off the list, we can deal with it at normal 287 * network IPL. 288 */ 289 s = splnet(); 290 IPFLOW_REMOVE(ipf); 291 splx(s); 292 ipflow_addstats(ipf); 293 RTFREE(ipf->ipf_ro.ro_rt); 294 ipflow_inuse--; 295 pool_put(&ipflow_pool, ipf); 296 } 297 298 struct ipflow * 299 ipflow_reap( 300 int just_one) 301 { 302 while (just_one || ipflow_inuse > ip_maxflows) { 303 struct ipflow *ipf, *maybe_ipf = NULL; 304 int s; 305 306 ipf = LIST_FIRST(&ipflowlist); 307 while (ipf != NULL) { 308 /* 309 * If this no longer points to a valid route 310 * reclaim it. 311 */ 312 if ((ipf->ipf_ro.ro_rt->rt_flags & RTF_UP) == 0) 313 goto done; 314 /* 315 * choose the one that's been least recently 316 * used or has had the least uses in the 317 * last 1.5 intervals. 318 */ 319 if (maybe_ipf == NULL || 320 ipf->ipf_timer < maybe_ipf->ipf_timer || 321 (ipf->ipf_timer == maybe_ipf->ipf_timer && 322 ipf->ipf_last_uses + ipf->ipf_uses < 323 maybe_ipf->ipf_last_uses + 324 maybe_ipf->ipf_uses)) 325 maybe_ipf = ipf; 326 ipf = LIST_NEXT(ipf, ipf_list); 327 } 328 ipf = maybe_ipf; 329 done: 330 /* 331 * Remove the entry from the flow table. 332 */ 333 s = splnet(); 334 IPFLOW_REMOVE(ipf); 335 splx(s); 336 ipflow_addstats(ipf); 337 RTFREE(ipf->ipf_ro.ro_rt); 338 if (just_one) 339 return ipf; 340 pool_put(&ipflow_pool, ipf); 341 ipflow_inuse--; 342 } 343 return NULL; 344 } 345 346 void 347 ipflow_slowtimo( 348 void) 349 { 350 struct ipflow *ipf, *next_ipf; 351 352 ipf = LIST_FIRST(&ipflowlist); 353 while (ipf != NULL) { 354 next_ipf = LIST_NEXT(ipf, ipf_list); 355 if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer)) { 356 ipflow_free(ipf); 357 } else { 358 ipf->ipf_last_uses = ipf->ipf_uses; 359 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 360 ipstat.ips_forward += ipf->ipf_uses; 361 ipstat.ips_fastforward += ipf->ipf_uses; 362 ipf->ipf_uses = 0; 363 } 364 ipf = next_ipf; 365 } 366 } 367 368 void 369 ipflow_create( 370 const struct route *ro, 371 struct mbuf *m) 372 { 373 const struct ip *const ip = mtod(m, struct ip *); 374 struct ipflow *ipf; 375 unsigned hash; 376 int s; 377 378 /* 379 * Don't create cache entries for ICMP messages. 380 */ 381 if (ip_maxflows == 0 || ip->ip_p == IPPROTO_ICMP) 382 return; 383 /* 384 * See if an existing flow struct exists. If so remove it from it's 385 * list and free the old route. If not, try to malloc a new one 386 * (if we aren't at our limit). 387 */ 388 ipf = ipflow_lookup(ip); 389 if (ipf == NULL) { 390 if (ipflow_inuse >= ip_maxflows) { 391 ipf = ipflow_reap(1); 392 } else { 393 ipf = pool_get(&ipflow_pool, PR_NOWAIT); 394 if (ipf == NULL) 395 return; 396 ipflow_inuse++; 397 } 398 bzero((caddr_t) ipf, sizeof(*ipf)); 399 } else { 400 s = splnet(); 401 IPFLOW_REMOVE(ipf); 402 splx(s); 403 ipflow_addstats(ipf); 404 RTFREE(ipf->ipf_ro.ro_rt); 405 ipf->ipf_uses = ipf->ipf_last_uses = 0; 406 ipf->ipf_errors = ipf->ipf_dropped = 0; 407 } 408 409 /* 410 * Fill in the updated information. 411 */ 412 ipf->ipf_ro = *ro; 413 ro->ro_rt->rt_refcnt++; 414 ipf->ipf_dst = ip->ip_dst; 415 ipf->ipf_src = ip->ip_src; 416 ipf->ipf_tos = ip->ip_tos; 417 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER); 418 ipf->ipf_start = time.tv_sec; 419 /* 420 * Insert into the approriate bucket of the flow table. 421 */ 422 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos); 423 s = splnet(); 424 IPFLOW_INSERT(&ipflowtable[hash], ipf); 425 splx(s); 426 } 427
Indexes created Mon Sep 22 13:09:51 GMT 2025