324 lines
8.2 KiB
C
324 lines
8.2 KiB
C
/*
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* Copyright (c) 1995 John Hay. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by John Hay.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY John Hay AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL John Hay OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: sap_tables.c,v 1.3 1997/02/22 16:01:01 peter Exp $
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*/
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#include "defs.h"
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#include <string.h>
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#include <stdlib.h>
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#define FIXLEN(s) { if ((s)->sa_len == 0) (s)->sa_len = sizeof (*(s));}
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sap_hash sap_head[SAPHASHSIZ];
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void
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sapinit(void)
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{
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int i;
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for (i=0; i<SAPHASHSIZ; i++)
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sap_head[i].forw = sap_head[i].back =
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(struct sap_entry *)&sap_head[i];
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}
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/*
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* XXX Make sure that this hash is good enough.
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*
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* This hash use the first 8 letters of the ServName and the ServType
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* to create a 32 bit hash value.
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*
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* NOTE: The first two letters of ServName will be used to generate
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* the lower bits of the hash. This is used to index into the hash table.
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*/
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#define rol(x) (((x * 2) & 0xFFFF) + ((x & 0x8000) != 0))
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int
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saphash(u_short ServType, char *ServName)
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{
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int hsh, i;
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char name[SERVNAMELEN];
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bzero(name, SERVNAMELEN);
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strncpy(name, ServName, SERVNAMELEN);
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ServName = name;
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hsh = 0;
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for (i=0;i<8;i++) {
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hsh = rol(hsh) + *ServName;
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ServName++;
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}
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hsh = rol(hsh) + (ServType >> 8);
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hsh = rol(hsh) + (ServType & 0xff);
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hsh = (hsh >> 7) ^ hsh;
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return hsh;
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}
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/*
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* Look for an exact match on ServType and ServName. It is
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* mostly used by the function that process SAP RESPONSE packets.
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*
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* A hash is created and used to index into the hash table. Then
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* that list is walk through searching for a match.
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*
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* If no match is found NULL is returned.
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*/
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struct sap_entry *
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sap_lookup(u_short ServType, char *ServName)
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{
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register struct sap_entry *sap;
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register struct sap_hash *sh;
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int hsh;
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hsh = saphash(ServType, ServName);
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sh = &sap_head[hsh & SAPHASHMASK];
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for(sap = sh->forw; sap != (sap_entry *)sh; sap = sap->forw) {
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if ((hsh == sap->hash) &&
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(ServType == sap->sap.ServType) &&
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(strncmp(ServName, sap->sap.ServName, SERVNAMELEN) == 0)) {
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return sap;
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}
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}
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return NULL;
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}
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/*
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* This returns the nearest service of the specified type. If no
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* suitable service is found or if that service is on the interface
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* where the request came from, NULL is returned.
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*
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* When checking interfaces clones must be considered also.
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*
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* XXX TODO:
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* Maybe we can use RIP tables to get the fastest service (ticks).
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*/
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struct sap_entry *
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sap_nearestserver(ushort ServType, struct interface *ifp)
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{
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register struct sap_entry *sap;
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register struct sap_entry *csap;
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struct sap_hash *sh;
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register struct sap_entry *best = NULL;
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register int besthops = HOPCNT_INFINITY;
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sh = sap_head;
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for (; sh < &sap_head[SAPHASHSIZ]; sh++)
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for(sap = sh->forw; sap != (sap_entry *)sh; sap = sap->forw) {
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if (ServType != sap->sap.ServType)
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continue;
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if (ifp == sap->ifp)
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continue;
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csap = sap->clone;
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while (csap) {
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if (ifp == csap->ifp)
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/*
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* I would have loved to use
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* something else here.
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*/
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goto next;
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csap = csap->clone;
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}
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if (ntohs(sap->sap.hops) < besthops) {
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best = sap;
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besthops = ntohs(best->sap.hops);
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}
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next:;
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}
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return best;
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}
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/*
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* Add a entry to the SAP table.
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*
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* If the malloc fail, the entry will silently be thrown away.
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*/
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void
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sap_add(struct sap_info *si, struct sockaddr *from)
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{
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register struct sap_entry *nsap;
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register struct sap_hash *sh;
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FIXLEN(from);
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nsap = malloc(sizeof(struct sap_entry));
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if (nsap == NULL)
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return;
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nsap->sap = *si;
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nsap->source = *from;
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nsap->clone = NULL;
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nsap->ifp = if_ifwithnet(from);
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nsap->state = RTS_CHANGED;
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nsap->timer = 0;
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nsap->hash = saphash(si->ServType, si->ServName);
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sh = &sap_head[nsap->hash & SAPHASHMASK];
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insque(nsap, sh);
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}
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/*
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* Change an existing SAP entry. If a clone exist for the old one,
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* check if it is cheaper. If it is change tothe clone, otherwise
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* delete all the clones.
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*/
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void
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sap_change(struct sap_entry *sap,
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struct sap_info *si,
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struct sockaddr *from)
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{
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struct sap_entry *osap = NULL;
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FIXLEN(from);
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/*
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* If the hopcount (metric) is HOPCNT_INFINITY (16) it means that
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* a service has gone down. We should keep it like that for 30
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* seconds, so that it will get broadcast and then change to a
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* clone if one exist.
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*/
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if (sap->clone && (ntohs(si->hops) != HOPCNT_INFINITY)) {
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/*
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* There are three possibilities:
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* 1. The new path is cheaper than the old one.
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* Free all the clones.
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*
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* 2. The new path is the same cost as the old ones.
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* If it is on the list of clones remove it
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* from the clone list and free it.
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*
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* 3. The new path is more expensive than the old one.
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* Use the values of the first clone and take it
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* out of the list, to be freed at the end.
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*/
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osap = sap->clone;
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if (ntohs(osap->sap.hops) > ntohs(si->hops)) {
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struct sap_entry *nsap;
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while (osap) {
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nsap = osap->clone;
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free(osap);
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osap = nsap;
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}
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sap->clone = NULL;
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} else if (ntohs(osap->sap.hops) == ntohs(si->hops)) {
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struct sap_entry *psap;
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psap = sap;
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while (osap) {
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if (equal(&osap->source, from)) {
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psap->clone = osap->clone;
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free(osap);
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osap = psap->clone;
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} else {
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psap = osap;
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osap = osap->clone;
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}
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}
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} else {
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from = &osap->source;
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si = &osap->sap;
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sap->clone = osap->clone;
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}
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}
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sap->sap = *si;
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sap->source = *from;
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sap->ifp = if_ifwithnet(from);
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sap->state = RTS_CHANGED;
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if (ntohs(si->hops) == HOPCNT_INFINITY)
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sap->timer = EXPIRE_TIME;
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else
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sap->timer = 0;
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if (osap)
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free(osap);
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}
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/*
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* Add a clone to the specified SAP entry. A clone is a different
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* route to the same service. We must know about them when we use
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* the split horizon algorithm.
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*
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* If the malloc fail, the entry will silently be thrown away.
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*/
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void
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sap_add_clone(struct sap_entry *sap,
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struct sap_info *clone,
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struct sockaddr *from)
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{
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register struct sap_entry *nsap;
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register struct sap_entry *csap;
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FIXLEN(from);
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nsap = malloc(sizeof(struct sap_entry));
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if (nsap == NULL)
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return;
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if (ftrace)
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fprintf(ftrace, "CLONE ADD %04.4X %s.\n",
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ntohs(clone->ServType),
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clone->ServName);
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nsap->sap = *clone;
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nsap->source = *from;
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nsap->clone = NULL;
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nsap->ifp = if_ifwithnet(from);
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nsap->state = RTS_CHANGED;
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nsap->timer = 0;
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nsap->hash = saphash(clone->ServType, clone->ServName);
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csap = sap;
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while (csap->clone)
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csap = csap->clone;
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csap->clone = nsap;
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}
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/*
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* Remove a SAP entry from the table and free the memory
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* used by it.
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*
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* If the service have clone, do a sap_change to it and free
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* the clone.
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*/
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void
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sap_delete(struct sap_entry *sap)
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{
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if (sap->clone) {
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sap_change(sap, &sap->clone->sap, &sap->clone->source);
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return;
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}
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remque(sap);
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free(sap);
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}
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