ip_flow.c revision 1.1
1 /* $NetBSD: ip_flow.c,v 1.1 1998/04/29 21:37:55 matt 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 52 #include <vm/vm.h> 53 #include <sys/sysctl.h> 54 55 #include <net/if.h> 56 #include <net/if_dl.h> 57 #include <net/route.h> 58 #include <net/pfil.h> 59 60 #include <netinet/in.h> 61 #include <netinet/in_systm.h> 62 #include <netinet/ip.h> 63 #include <netinet/in_pcb.h> 64 #include <netinet/in_var.h> 65 #include <netinet/ip_var.h> 66 67 #define IPFLOW_TIMER (5 * PR_SLOWHZ) 68 #define IPFLOW_HASHSIZE (1 << IPFLOW_HASHBITS) 69 static LIST_HEAD(ipflowhead, ipflow) ipflows[IPFLOW_HASHSIZE]; 70 static int ipflow_inuse; 71 #define IPFLOW_MAX 256 72 73 static int ipflow_active = 0; 74 75 static unsigned 76 ipflow_hash( 77 struct in_addr dst, 78 struct in_addr src, 79 unsigned tos) 80 { 81 unsigned hash = tos; 82 int idx; 83 for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS) 84 hash += (dst.s_addr >> (32 - idx)) + (src.s_addr >> idx); 85 return hash & (IPFLOW_HASHSIZE-1); 86 } 87 88 static struct ipflow * 89 ipflow_lookup( 90 const struct ip *ip) 91 { 92 unsigned hash; 93 struct ipflow *ipf; 94 95 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos); 96 97 ipf = LIST_FIRST(&ipflows[hash]); 98 while (ipf != NULL) { 99 if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr 100 && ip->ip_src.s_addr == ipf->ipf_src.s_addr 101 && ip->ip_tos == ipf->ipf_tos) 102 break; 103 ipf = LIST_NEXT(ipf, ipf_next); 104 } 105 return ipf; 106 } 107 108 int 109 ipflow_fastforward( 110 struct mbuf *m) 111 { 112 struct ip *ip; 113 struct ipflow *ipf; 114 struct rtentry *rt; 115 u_int32_t sum; 116 int error; 117 118 /* 119 * Are we forwarding packets? Big enough for an IP packet? 120 */ 121 if (!ipforwarding || !ipflow_active || m->m_len < sizeof(struct ip)) 122 return 0; 123 /* 124 * IP header with no option and valid version and length 125 */ 126 ip = mtod(m, struct ip *); 127 if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) 128 || ntohs(ip->ip_len) > m->m_pkthdr.len) 129 return 0; 130 /* 131 * Find a flow. 132 */ 133 if ((ipf = ipflow_lookup(ip)) == NULL) 134 return 0; 135 136 /* 137 * Route and interface still up? 138 */ 139 rt = ipf->ipf_ro.ro_rt; 140 if ((rt->rt_flags & RTF_UP) == 0 || (rt->rt_ifp->if_flags & IFF_UP) == 0) 141 return 0; 142 143 /* 144 * Packet size OK? TTL? 145 */ 146 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC) 147 return 0; 148 149 /* 150 * Everything checks out and so we can forward this packet. 151 * Modify the TTL and incrementally change the checksum. 152 * On little endian machine, the TTL is in LSB position 153 * (so we can simply add) while on big-endian it's in the 154 * MSB position (so we have to do two calculation; the first 155 * is the add and second is to wrap the results into 17 bits, 156 * 16 bits and a carry). 157 */ 158 ip->ip_ttl -= IPTTLDEC; 159 #if BYTE_ORDER == LITTLE_ENDIAN 160 sum = ip->ip_sum + IPTTLDEC; 161 #endif 162 #if BYTE_ORDER == BIG_ENDIAN 163 sum = ip->ip_sum + (IPTTLDEC << 8); 164 sum = (sum & 0xFFFF) + (sum >> 16); 165 #endif 166 if (sum > 0x10000) /* add in carry if needed */ 167 sum++; 168 ip->ip_sum = sum; /* bit 16 is dropped */ 169 170 /* 171 * Send the packet on it's way. All we can get back is ENOBUFS 172 */ 173 ipf->ipf_uses++; 174 ipf->ipf_timer = IPFLOW_TIMER; 175 if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, &ipf->ipf_ro.ro_dst, rt)) != 0) { 176 if (error == ENOBUFS) 177 ipf->ipf_dropped++; 178 else 179 ipf->ipf_errors++; 180 } 181 return 1; 182 } 183 184 static void 186 ipflow_addstats( 187 struct ipflow *ipf) 188 { 189 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 190 ipstat.ips_cantforward += ipf->ipf_errors + ipf->ipf_dropped; 191 ipstat.ips_forward += ipf->ipf_uses; 192 ipstat.ips_fastforward += ipf->ipf_uses; 193 } 194 195 static void 196 ipflow_free( 197 struct ipflow *ipf) 198 { 199 int s; 200 /* 201 * Remove the flow from the hash table (at elevated IPL). 202 * Once it's off the list, we can deal with it at normal 203 * network IPL. 204 */ 205 s = splimp(); 206 LIST_REMOVE(ipf, ipf_next); 207 splx(s); 208 ipflow_addstats(ipf); 209 RTFREE(ipf->ipf_ro.ro_rt); 210 ipflow_inuse--; 211 FREE(ipf, M_IPFLOW); 212 } 213 214 static struct ipflow * 215 ipflow_reap( 216 void) 217 { 218 struct ipflow *ipf, *maybe_ipf = NULL; 219 int idx; 220 int s; 221 222 for (idx = 0; idx < IPFLOW_HASHSIZE; idx++) { 223 ipf = LIST_FIRST(&ipflows[idx]); 224 while (ipf != NULL) { 225 /* 226 * If this no longer points to a valid route 227 * reclaim it. 228 */ 229 if ((ipf->ipf_ro.ro_rt->rt_flags & RTF_UP) == 0) 230 goto done; 231 /* 232 * choose the one that's been least recently used 233 * or has had the least uses in the last 1.5 234 * intervals. 235 */ 236 if (ipf == NULL 237 || ipf->ipf_timer < maybe_ipf->ipf_timer 238 || (ipf->ipf_timer == maybe_ipf->ipf_timer 239 && ipf->ipf_last_uses + ipf->ipf_uses < 240 maybe_ipf->ipf_last_uses + 241 maybe_ipf->ipf_uses)) 242 maybe_ipf = ipf; 243 ipf = LIST_NEXT(ipf, ipf_next); 244 } 245 } 246 ipf = maybe_ipf; 247 done: 248 /* 249 * Remove the entry from the flow table. 250 */ 251 s = splimp(); 252 LIST_REMOVE(ipf, ipf_next); 253 splx(s); 254 ipflow_addstats(ipf); 255 RTFREE(ipf->ipf_ro.ro_rt); 256 return ipf; 257 } 258 259 void 260 ipflow_slowtimo( 261 void) 262 { 263 struct ipflow *ipf; 264 int idx; 265 266 for (idx = 0; idx < IPFLOW_HASHSIZE; idx++) { 267 ipf = LIST_FIRST(&ipflows[idx]); 268 while (ipf != NULL) { 269 struct ipflow *next_ipf = LIST_NEXT(ipf, ipf_next); 270 if (--ipf->ipf_timer == 0) { 271 ipflow_free(ipf); 272 } else { 273 ipf->ipf_last_uses = ipf->ipf_uses; 274 ipf->ipf_ro.ro_rt->rt_use += ipf->ipf_uses; 275 ipstat.ips_forward += ipf->ipf_uses; 276 ipstat.ips_fastforward += ipf->ipf_uses; 277 ipf->ipf_uses = 0; 278 } 279 ipf = next_ipf; 280 } 281 } 282 } 283 284 void 285 ipflow_create( 286 const struct route *ro, 287 struct mbuf *m) 288 { 289 const struct ip *const ip = mtod(m, struct ip *); 290 struct ipflow *ipf; 291 unsigned hash; 292 int s; 293 294 /* 295 * Don't create cache entries for ICMP messages. 296 */ 297 if (!ipflow_active || ip->ip_p == IPPROTO_ICMP) 298 return; 299 /* 300 * See if an existing flow struct exists. If so remove it from it's 301 * list and free the old route. If not, try to malloc a new one 302 * (if we aren't at our limit). 303 */ 304 ipf = ipflow_lookup(ip); 305 if (ipf == NULL) { 306 if (ipflow_inuse == IPFLOW_MAX) { 307 ipf = ipflow_reap(); 308 } else { 309 ipf = (struct ipflow *) malloc(sizeof(*ipf), M_IPFLOW, 310 M_NOWAIT); 311 if (ipf == NULL) 312 return; 313 ipflow_inuse++; 314 } 315 bzero((caddr_t) ipf, sizeof(*ipf)); 316 } else { 317 s = splimp(); 318 LIST_REMOVE(ipf, ipf_next); 319 splx(s); 320 ipflow_addstats(ipf); 321 RTFREE(ipf->ipf_ro.ro_rt); 322 ipf->ipf_uses = ipf->ipf_last_uses = 0; 323 ipf->ipf_errors = ipf->ipf_dropped = 0; 324 } 325 326 /* 327 * Fill in the updated information. 328 */ 329 ipf->ipf_ro = *ro; 330 ro->ro_rt->rt_refcnt++; 331 ipf->ipf_dst = ip->ip_dst; 332 ipf->ipf_src = ip->ip_src; 333 ipf->ipf_tos = ip->ip_tos; 334 ipf->ipf_timer = IPFLOW_TIMER; 335 ipf->ipf_start = time.tv_sec; 336 /* 337 * Insert into the approriate bucket of the flow table. 338 */ 339 hash = ipflow_hash(ip->ip_dst, ip->ip_src, ip->ip_tos); 340 s = splimp(); 341 LIST_INSERT_HEAD(&ipflows[hash], ipf, ipf_next); 342 splx(s); 343 } 344
Indexes created Sun Sep 21 20:09:37 GMT 2025