1 /* $NetBSD: ip_flow.c,v 1.12 1999/01/28 21:29:27 itohy 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 * IP header with no option and valid version and length 159 */ 160 ip = mtod(m, struct ip *); 161 iplen = ntohs(ip->ip_len); 162 if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) || 163 iplen > m->m_pkthdr.len) 164 return 0; 165 /* 166 * Find a flow. 167 */ 168 if ((ipf = ipflow_lookup(ip)) == NULL) 169 return 0; 170 171 /* 172 * Veryify the IP header checksum. 173 */ 174 if (in_cksum(m, sizeof(struct ip)) != 0) 175 return 0; 176 177 /* 178 * Route and interface still up? 179 */ 180 rt = ipf->ipf_ro.ro_rt; 181 if ((rt->rt_flags & RTF_UP) == 0 || 182 (rt->rt_ifp->if_flags & IFF_UP) == 0) 183 return 0; 184 185 /* 186 * Packet size OK? TTL? 187 */ 188 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC) 189 return 0; 190 191 /* 192 * Everything checks out and so we can forward this packet. 193 * Modify the TTL and incrementally change the checksum. 194 * 195 * This method of adding the checksum works on either endian CPU. 196 * If htons() is inlined, all the arithmetic is folded; otherwise 197 * the htons()s are combined by CSE due to the __const__ attribute. 198 */ 199 ip->ip_ttl -= IPTTLDEC; 200 if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8)) 201 ip->ip_sum -= ~htons(IPTTLDEC << 8); 202 else 203 ip->ip_sum += htons(IPTTLDEC << 8); 204 205 /* 206 * Trim the packet in case it's too long.. 207 */ 208 if (m->m_pkthdr.len > iplen) { 209 if (m->m_len == m->m_pkthdr.len) { 210 m->m_len = iplen; 211 m->m_pkthdr.len = iplen; 212 } else 213 m_adj(m, iplen - m->m_pkthdr.len); 214 } 215 216 /* 217 * Send the packet on it's way. All we can get back is ENOBUFS 218 */ 219 ipf->ipf_uses++; 220 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER); 221 if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 222 &ipf->ipf_ro.ro_dst, rt)) != 0) { 223 if (error == ENOBUFS) 224 ipf->ipf_dropped++; 225 else 226 ipf->ipf_errors++; 227 } 228 return 1; 229 } 230 231 static void 232 ipflow_addstats( 233 struct ipflow *ipf) 234 { 235 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 236 ipstat.ips_cantforward += ipf->ipf_errors + ipf->ipf_dropped; 237 ipstat.ips_forward += ipf->ipf_uses; 238 ipstat.ips_fastforward += ipf->ipf_uses; 239 } 240 241 static void 242 ipflow_free( 243 struct ipflow *ipf) 244 { 245 int s; 246 /* 247 * Remove the flow from the hash table (at elevated IPL). 248 * Once it's off the list, we can deal with it at normal 249 * network IPL. 250 */ 251 s = splimp(); 252 IPFLOW_REMOVE(ipf); 253 splx(s); 254 ipflow_addstats(ipf); 255 RTFREE(ipf->ipf_ro.ro_rt); 256 ipflow_inuse--; 257 pool_put(&ipflow_pool, ipf); 258 } 259 260 struct ipflow * 261 ipflow_reap( 262 int just_one) 263 { 264 while (just_one || ipflow_inuse > ip_maxflows) { 265 struct ipflow *ipf, *maybe_ipf = NULL; 266 int s; 267 268 ipf = LIST_FIRST(&ipflowlist); 269 while (ipf != NULL) { 270 /* 271 * If this no longer points to a valid route 272 * reclaim it. 273 */ 274 if ((ipf->ipf_ro.ro_rt->rt_flags & RTF_UP) == 0) 275 goto done; 276 /* 277 * choose the one that's been least recently 278 * used or has had the least uses in the 279 * last 1.5 intervals. 280 */ 281 if (maybe_ipf == NULL || 282 ipf->ipf_timer < maybe_ipf->ipf_timer || 283 (ipf->ipf_timer == maybe_ipf->ipf_timer && 284 ipf->ipf_last_uses + ipf->ipf_uses < 285 maybe_ipf->ipf_last_uses + 286 maybe_ipf->ipf_uses)) 287 maybe_ipf = ipf; 288 ipf = LIST_NEXT(ipf, ipf_list); 289 } 290 ipf = maybe_ipf; 291 done: 292 /* 293 * Remove the entry from the flow table. 294 */ 295 s = splimp(); 296 IPFLOW_REMOVE(ipf); 297 splx(s); 298 ipflow_addstats(ipf); 299 RTFREE(ipf->ipf_ro.ro_rt); 300 if (just_one) 301 return ipf; 302 pool_put(&ipflow_pool, ipf); 303 ipflow_inuse--; 304 } 305 return NULL; 306 } 307 308 void 309 ipflow_slowtimo( 310 void) 311 { 312 struct ipflow *ipf, *next_ipf; 313 314 ipf = LIST_FIRST(&ipflowlist); 315 while (ipf != NULL) { 316 next_ipf = LIST_NEXT(ipf, ipf_list); 317 if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer)) { 318 ipflow_free(ipf); 319 } else { 320 ipf->ipf_last_uses = ipf->ipf_uses; 321 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 322 ipstat.ips_forward += ipf->ipf_uses; 323 ipstat.ips_fastforward += ipf->ipf_uses; 324 ipf->ipf_uses = 0; 325 } 326 ipf = next_ipf; 327 } 328 } 329 330 void 331 ipflow_create( 332 const struct route *ro, 333 struct mbuf *m) 334 { 335 const struct ip *const ip = mtod(m, struct ip *); 336 struct ipflow *ipf; 337 unsigned hash; 338 int s; 339 340 /* 341 * Don't create cache entries for ICMP messages. 342 */ 343 if (ip_maxflows == 0 || ip->ip_p == IPPROTO_ICMP) 344 return; 345 /* 346 * See if an existing flow struct exists. If so remove it from it's 347 * list and free the old route. If not, try to malloc a new one 348 * (if we aren't at our limit). 349 */ 350 ipf = ipflow_lookup(ip); 351 if (ipf == NULL) { 352 if (ipflow_inuse >= ip_maxflows) { 353 ipf = ipflow_reap(1); 354 } else { 355 ipf = pool_get(&ipflow_pool, PR_NOWAIT); 356 if (ipf == NULL) 357 return; 358 ipflow_inuse++; 359 } 360 bzero((caddr_t) ipf, sizeof(*ipf)); 361 } else { 362 s = splimp(); 363 IPFLOW_REMOVE(ipf); 364 splx(s); 365 ipflow_addstats(ipf); 366 RTFREE(ipf->ipf_ro.ro_rt); 367 ipf->ipf_uses = ipf->ipf_last_uses = 0; 368 ipf->ipf_errors = ipf->ipf_dropped = 0; 369 } 370 371 /* 372 * Fill in the updated information. 373 */ 374 ipf->ipf_ro = *ro; 375 ro->ro_rt->rt_refcnt++; 376 ipf->ipf_dst = ip->ip_dst; 377 ipf->ipf_src = ip->ip_src; 378 ipf->ipf_tos = ip->ip_tos; 379 PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER); 380 ipf->ipf_start = time.tv_sec; 381 /* 382 * Insert into the approriate bucket of the flow table. 383 */ 384 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos); 385 s = splimp(); 386 IPFLOW_INSERT(&ipflowtable[hash], ipf); 387 splx(s); 388 } 389