sap_tables.c revision 108533
1/* 2 * Copyright (c) 1995 John Hay. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 3. All advertising materials mentioning features or use of this software 13 * must display the following acknowledgement: 14 * This product includes software developed by John Hay. 15 * 4. Neither the name of the author nor the names of any co-contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY John Hay AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL John Hay OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * $FreeBSD: head/usr.sbin/IPXrouted/sap_tables.c 108533 2003-01-01 18:49:04Z schweikh $ 32 */ 33 34#include "defs.h" 35#include <string.h> 36#include <stdlib.h> 37 38#define FIXLEN(s) { if ((s)->sa_len == 0) (s)->sa_len = sizeof (*(s));} 39 40sap_hash sap_head[SAPHASHSIZ]; 41 42void 43sapinit(void) 44{ 45 int i; 46 47 for (i=0; i<SAPHASHSIZ; i++) 48 sap_head[i].forw = sap_head[i].back = 49 (struct sap_entry *)&sap_head[i]; 50} 51 52/* 53 * This hash use the first 14 letters of the ServName and the ServType 54 * to create a 32 bit hash value. 55 */ 56int 57saphash(u_short ServType, char *ServName) 58{ 59 int hsh, i; 60 char name[SERVNAMELEN]; 61 62 bzero(name, SERVNAMELEN); 63 strncpy(name, ServName, SERVNAMELEN); 64 ServName = name; 65 66 hsh = 0; 67 68#define SMVAL 33 69 70 hsh = hsh * SMVAL + (ServType & 0xff); 71 hsh = hsh * SMVAL + (ServType >> 8); 72 73 for (i=0;i<14;i++) { 74 hsh = hsh * SMVAL + *ServName++; 75 ServName++; 76 } 77 78#undef SMVAL 79 80 return hsh; 81} 82 83/* 84 * Look for an exact match on ServType and ServName. It is 85 * mostly used by the function that process SAP RESPONSE packets. 86 * 87 * A hash is created and used to index into the hash table. Then 88 * that list is walk through searching for a match. 89 * 90 * If no match is found NULL is returned. 91 */ 92struct sap_entry * 93sap_lookup(u_short ServType, char *ServName) 94{ 95 register struct sap_entry *sap; 96 register struct sap_hash *sh; 97 int hsh; 98 99 hsh = saphash(ServType, ServName); 100 sh = &sap_head[hsh & SAPHASHMASK]; 101 102 for(sap = sh->forw; sap != (sap_entry *)sh; sap = sap->forw) { 103 if ((hsh == sap->hash) && 104 (ServType == sap->sap.ServType) && 105 (strncmp(ServName, sap->sap.ServName, SERVNAMELEN) == 0)) { 106 return sap; 107 } 108 } 109 return NULL; 110} 111 112/* 113 * This returns the nearest service of the specified type. If no 114 * suitable service is found or if that service is on the interface 115 * where the request came from, NULL is returned. 116 * 117 * When checking interfaces clones must be considered also. 118 * 119 * XXX TODO: 120 * Maybe we can use RIP tables to get the fastest service (ticks). 121 */ 122struct sap_entry * 123sap_nearestserver(ushort ServType, struct interface *ifp) 124{ 125 register struct sap_entry *sap; 126 register struct sap_entry *csap; 127 struct sap_hash *sh; 128 register struct sap_entry *best = NULL; 129 register int besthops = HOPCNT_INFINITY; 130 131 sh = sap_head; 132 133 for (; sh < &sap_head[SAPHASHSIZ]; sh++) 134 for(sap = sh->forw; sap != (sap_entry *)sh; sap = sap->forw) { 135 if (ServType != sap->sap.ServType) 136 continue; 137 138 if (ntohs(sap->sap.hops) < besthops) { 139 best = sap; 140 besthops = ntohs(best->sap.hops); 141 } 142next:; 143 } 144 return best; 145} 146 147/* 148 * Add an entry to the SAP table. 149 * 150 * If the malloc fail, the entry will silently be thrown away. 151 */ 152void 153sap_add(struct sap_info *si, struct sockaddr *from) 154{ 155 register struct sap_entry *nsap; 156 register struct sap_hash *sh; 157 158 if (ntohs(si->hops) == HOPCNT_INFINITY) 159 return; 160 161 FIXLEN(from); 162 nsap = malloc(sizeof(struct sap_entry)); 163 if (nsap == NULL) 164 return; 165 166 nsap->sap = *si; 167 nsap->source = *from; 168 nsap->clone = NULL; 169 nsap->ifp = if_ifwithnet(from); 170 nsap->state = RTS_CHANGED; 171 nsap->timer = 0; 172 nsap->hash = saphash(si->ServType, si->ServName); 173 174 sh = &sap_head[nsap->hash & SAPHASHMASK]; 175 176 insque(nsap, sh); 177 TRACE_SAP_ACTION("ADD", nsap); 178} 179 180/* 181 * Change an existing SAP entry. If a clone exist for the old one, 182 * check if it is cheaper. If it is change tothe clone, otherwise 183 * delete all the clones. 184 */ 185void 186sap_change(struct sap_entry *sap, 187 struct sap_info *si, 188 struct sockaddr *from) 189{ 190 struct sap_entry *osap = NULL; 191 192 FIXLEN(from); 193 TRACE_SAP_ACTION("CHANGE FROM", sap); 194 /* 195 * If the hopcount (metric) is HOPCNT_INFINITY (16) it means that 196 * a service has gone down. We should keep it like that for 30 197 * seconds, so that it will get broadcast and then change to a 198 * clone if one exist. 199 */ 200 if (sap->clone && (ntohs(si->hops) != HOPCNT_INFINITY)) { 201 /* 202 * There are three possibilities: 203 * 1. The new path is cheaper than the old one. 204 * Free all the clones. 205 * 206 * 2. The new path is the same cost as the old ones. 207 * If it is on the list of clones remove it 208 * from the clone list and free it. 209 * 210 * 3. The new path is more expensive than the old one. 211 * Use the values of the first clone and take it 212 * out of the list, to be freed at the end. 213 */ 214 osap = sap->clone; 215 if (ntohs(osap->sap.hops) > ntohs(si->hops)) { 216 struct sap_entry *nsap; 217 218 while (osap) { 219 nsap = osap->clone; 220 TRACE_SAP_ACTION("DELETE", osap); 221 free(osap); 222 osap = nsap; 223 } 224 sap->clone = NULL; 225 } else if (ntohs(osap->sap.hops) == ntohs(si->hops)) { 226 struct sap_entry *psap; 227 228 psap = sap; 229 while (osap) { 230 if (equal(&osap->source, from)) { 231 psap->clone = osap->clone; 232 TRACE_SAP_ACTION("DELETE", osap); 233 free(osap); 234 osap = psap->clone; 235 } else { 236 psap = osap; 237 osap = osap->clone; 238 } 239 } 240 } else { 241 from = &osap->source; 242 si = &osap->sap; 243 sap->clone = osap->clone; 244 } 245 } 246 sap->sap = *si; 247 sap->source = *from; 248 sap->ifp = if_ifwithnet(from); 249 sap->state = RTS_CHANGED; 250 if (ntohs(si->hops) == HOPCNT_INFINITY) 251 sap->timer = EXPIRE_TIME; 252 else 253 sap->timer = 0; 254 255 if (osap) { 256 TRACE_SAP_ACTION("DELETE", osap); 257 free(osap); 258 } 259 TRACE_SAP_ACTION("CHANGE TO", sap); 260} 261 262/* 263 * Add a clone to the specified SAP entry. A clone is a different 264 * route to the same service. We must know about them when we use 265 * the split horizon algorithm. 266 * 267 * If the malloc fail, the entry will silently be thrown away. 268 */ 269void 270sap_add_clone(struct sap_entry *sap, 271 struct sap_info *clone, 272 struct sockaddr *from) 273{ 274 register struct sap_entry *nsap; 275 register struct sap_entry *csap; 276 277 if (ntohs(clone->hops) == HOPCNT_INFINITY) 278 return; 279 280 FIXLEN(from); 281 nsap = malloc(sizeof(struct sap_entry)); 282 if (nsap == NULL) 283 return; 284 285 if (ftrace) 286 fprintf(ftrace, "CLONE ADD %04.4X %s.\n", 287 ntohs(clone->ServType), 288 clone->ServName); 289 290 nsap->sap = *clone; 291 nsap->source = *from; 292 nsap->clone = NULL; 293 nsap->ifp = if_ifwithnet(from); 294 nsap->state = RTS_CHANGED; 295 nsap->timer = 0; 296 nsap->hash = saphash(clone->ServType, clone->ServName); 297 298 csap = sap; 299 while (csap->clone) 300 csap = csap->clone; 301 csap->clone = nsap; 302 TRACE_SAP_ACTION("ADD CLONE", nsap); 303} 304 305/* 306 * Remove a SAP entry from the table and free the memory 307 * used by it. 308 * 309 * If the service have clone, do a sap_change to it and free 310 * the clone. 311 */ 312void 313sap_delete(struct sap_entry *sap) 314{ 315 if (sap->clone) { 316 sap_change(sap, &sap->clone->sap, &sap->clone->source); 317 return; 318 } 319 remque(sap); 320 TRACE_SAP_ACTION("DELETE", sap); 321 free(sap); 322} 323