cache.c~

此dns服务器是在mydns基础上改写

/**************************************************************************************************
	CACHE_HASH
	Returns hash value.
**************************************************************************************************/
static inline uint32_t
cache_hash(CACHE *ThisCache, uint32_t initval, void *buf, register size_t buflen)
#if (HASH_TYPE == ORIGINAL_HASH)
{
	register uint32_t	hash;
	register unsigned char *p;

	/* Generate hash value */
	for (hash = initval, p = (unsigned char *)buf; p < (unsigned char *)(buf + buflen); p++)
	{
		register int tmp;
		hash = (hash << 4) + (*p);
		if ((tmp = (hash & 0xf0000000)))
		{
			hash = hash ^ (tmp >> 24);
			hash = hash ^ tmp;
		}
	}
	return (hash % ThisCache->slots);
}
#elif (HASH_TYPE == ADDITIVE_HASH)
{
	register uint32_t	hash;
	register unsigned char *p;

	for (hash = initval, p = (unsigned char *)buf; p < (unsigned char *)(buf + buflen); p++)
		hash += *p;
	return (hash % ThisCache->slots);
}
#elif (HASH_TYPE == ROTATING_HASH)
{
	register uint32_t	hash;
	register unsigned char *p;

	for (hash = initval, p = (unsigned char *)buf; p < (unsigned char *)(buf + buflen); p++)
		hash = (hash << 4) ^ (hash >> 28) ^ (*p);
	return ((hash ^ (hash>>10) ^ (hash>>20)) & ThisCache->mask);
}
#elif (HASH_TYPE == FNV_HASH)
{
	register uint32_t	hash = FNV_32_INIT;
	unsigned char *bp = (unsigned char *)buf;
	unsigned char *be = bp + buflen;

	while (bp < be)
	{
		hash *= FNV_32_PRIME;
		hash ^= (uint32_t)*bp++;
	}
	hash *= FNV_32_PRIME;
	hash ^= (uint32_t)initval;

	if (ThisCache->bits == 16)
		return ((hash >> 16) ^ (hash & (((uint32_t)1 << 16) - 1)));
	else
		return (hash % ThisCache->slots);
}
#else
#	error Hash method unknown or unspecified
#endif
/*--- cache_hash() ------------------------------------------------------------------------------*/


/**************************************************************************************************
	ZONE_CACHE_FIND
	Returns the SOA/RR from cache (or via the database) or NULL if `name' doesn't match.
**************************************************************************************************/
void *
zone_cache_find(TASK *t, uint32_t zone, char *origin, dns_qtype_t type,
					 char *name, size_t namelen, int *errflag, MYDNS_SOA *parent)
{
	register uint32_t	hash = 0;
	register CNODE		*n;
	MYDNS_SOA			*soa = NULL;
	MYDNS_RR				*rr = NULL;
	CACHE					*C;										/* Which cache to use when inserting */

#if DEBUG_ENABLED && DEBUG_CACHE
	Debug("%s: zone_cache_find(zone=%u, origin='%s', name='%s', qtype=%s)",
			desctask(t), zone, origin, name, mydns_qtype_str(type));
#endif

	*errflag = 0;

	if (!name)
		return (NULL);
	
	/*add by zyl 20080331 --begin*/
	char	ipchs[9];	
	memset(ipchs,0,9);

	iplong_to_ipchs(ipchs, 9, t->addr4.sin_addr.s_addr);
	/*add by zyl 20080331 --end*/

	if (ZoneCache)
	{
		hash = cache_hash(ZoneCache, zone + type, name, namelen);
#if USE_NEGATIVE_CACHE
		/* Check negative reply cache */
		if (NegativeCache)
		{
			NegativeCache->questions++;

			/* Look at the appropriate node.  Descend list and find match. */
			for (n = NegativeCache->nodes[hash]; n; n = n->next_node)
				if ((n->namelen == namelen) && (n->zone == zone) && (n->type == type))
				{
					if (!n->name)
						Errx(_("negative cache node %p at hash %u has NULL name"), n, hash);
					if (!memcmp(n->name, name, namelen))
					{
						/* Is the node expired? */
						if (n->expire && (current_time > n->expire))
						{
							cache_free_node(NegativeCache, hash, n);
							break;
						}
						NegativeCache->hits++;

						/* Found in cache; move to head of usefulness list */
						mrulist_del(NegativeCache, n);
						mrulist_add(NegativeCache, n);
						return NULL;
					}
				}
			NegativeCache->misses++;
		}
#endif

		/* Not in negative cache, so look in zone cache */
		ZoneCache->questions++;

		/* Look at the appropriate node.  Descend list and find match. */
		for (n = ZoneCache->nodes[hash]; n; n = n->next_node)
		{
			if ((n->namelen == namelen) && (n->zone == zone) && (n->type == type))
			{
				if (!n->name)
					Errx(_("zone cache node %p at hash %u has NULL name"), n, hash);
				if (!memcmp(n->name, name, namelen))
				{
					/* Is the node expired? */
					if (n->expire && (current_time > n->expire))
					{
						cache_free_node(ZoneCache, hash, n);
						break;
					}
					ZoneCache->hits++;

					/* Found in cache; move to head of usefulness list */
					mrulist_del(ZoneCache, n);
					mrulist_add(ZoneCache, n);
					if (type == DNS_QTYPE_SOA)
						return (n->data ? mydns_soa_dup(n->data, 1) : NULL);
					else
						return (n->data ? mydns_rr_dup(n->data, 1) : NULL);
				}
			}
		}
	}

	/* Result not found in cache; Get answer from database */
	if (type == DNS_QTYPE_SOA)
	{
		/* Try to load from database */
#if DEBUG_ENABLED && DEBUG_SQL_QUERIES
		Debug("%s: SQL query: table \"%s\", origin=\"%s\"", desctask(t), mydns_soa_table_name, name);
#endif
		if (mydns_soa_load(sql, &soa, name) != 0)
		{
			sql_reopen();
			if (mydns_soa_load(sql, &soa, name) != 0)
			{
				WarnSQL(sql, "%s: %s", name, _("error loading SOA"));
				*errflag = 1;
				return (NULL);
			}
		}
	


		/*add by zyl 20080403 __begin*/
		
		/*select the most matched soa*/
		//select_matched_zone(sql,&soa,name,type,origin,ipchs);		

		/*add by zyl 20080403 __end*/
#ifdef DN_COLUMN_NAMES
		if (soa && dn_default_ns)
			strncpy(soa->ns, dn_default_ns, sizeof(soa->ns)-1);
#endif

#if USE_NEGATIVE_CACHE
		if (!(C = soa ? ZoneCache : NegativeCache))
#else
		if (!(soa && (C = ZoneCache)))
#endif
			return ((void *)soa);

		/* Don't cache if TTL is 0 */
		if (soa && !soa->ttl)
			return ((void *)soa);
	}
	else
	{

#if DEBUG_ENABLED && DEBUG_SQL_QUERIES
		Debug("%s: SQL query: table \"%s\", zone=%u,type=\"%s\",name=\"%s\", requestor_ip_section=\"%s\"",
				desctask(t), mydns_rr_table_name, zone, mydns_qtype_str(type), name,ipchs);
#endif
		if (mydns_rr_load(sql, &rr, zone, type, name, origin, ipchs) != 0)
		{
			sql_reopen();
			if (mydns_rr_load(sql, &rr, zone, type, name, origin, ipchs) != 0)
			{
				WarnSQL(sql, _("error finding %s type resource records for name `%s' in zone %u"),
						  mydns_qtype_str(type), name, zone);
				sql_reopen();
				*errflag = 1;
				return (NULL);
			}
		}

#ifdef DN_COLUMN_NAMES
		/* DN database has no TTL - use parent's */
		if (rr && parent && parent->ttl)
			rr->ttl = parent->ttl;
#endif

#if USE_NEGATIVE_CACHE
		if (!(C = rr ? ZoneCache : NegativeCache))
#else
		if (!(rr && (C = ZoneCache)))
#endif
			return ((void *)rr);

		/* Don't cache if TTL of this RR (or the parent SOA) is 0 */
		if ((rr && !rr->ttl) || (parent && !parent->ttl))
			return ((void *)rr);
	}
	C->misses++;

	/* If the cache is full, delete the least recently used node and add new node */
	if (C->count >= C->limit)
	{
		if (C->mruTail)
		{
			C->removed++;
			C->removed_secs += current_time - C->mruTail->insert_time;
			cache_free_node(C, C->mruTail->hash, C->mruTail);
		}
		else
			return (type == DNS_QTYPE_SOA ? (void *)soa : (void *)rr);
	}

	/* Add to cache */
	C->in++;
	if (!(n = calloc(1, sizeof(CNODE))))
		Err(_("out of memory"));
	n->hash = hash;
	n->zone = zone;
	n->type = type;
	strncpy(n->name, name, sizeof(n->name)-1);
	n->namelen = namelen;
	n->insert_time = current_time;
	if (type == DNS_QTYPE_SOA)
	{
		if (C == ZoneCache)
			n->data = mydns_soa_dup(soa, 1);

		if (soa && (soa->ttl < C->expire))
			n->expire = current_time + soa->ttl;
		else if (C->expire)
			n->expire = current_time + C->expire;
	}
	else
	{
		if (C == ZoneCache)
			n->data = mydns_rr_dup(rr, 1);

		if (rr && (rr->ttl < C->expire))
			n->expire = current_time + rr->ttl;
		else if (C->expire)
			n->expire = current_time + C->expire;
	}
	n->next_node = C->nodes[hash];

#if DEBUG_ENABLED && DEBUG_CACHE
	Debug("%s: Added to cache: zone=%u, type=%s, name='%s'", desctask(t), zone, mydns_qtype_str(type), name);
#endif

	/* Add node to cache */
	C->nodes[hash] = n;
	C->count++;

	/* Add node to head of MRU list */
	mrulist_add(C, n);

	return (type == DNS_QTYPE_SOA ? (void *)soa : (void *)rr);
}
/*--- zone_cache_find() --------------------------------------------------------------------------*/


/**************************************************************************************************
	REPLY_CACHE_FIND
	Attempt to find the reply data whole in the cache.
	Returns nonzero if found, 0 if not found.
	If found, fills in t->reply and t->replylen.
**************************************************************************************************/
int
reply_cache_find(TASK *t)
{
	register uint32_t	hash;
	register CNODE		*n;
	register void		*p;

#if DEBUG_ENABLED && DEBUG_CACHE
	Debug("%s: reply_cache_find(qdlen=%d proto=%d)", desctask(t), t->qdlen, t->protocol);
#endif

	if (!ReplyCache || t->qdlen > DNS_MAXPACKETLEN_UDP)
		return (0);

#if STATUS_ENABLED
	/* Status requests aren't cached */
	if (t->qclass == DNS_CLASS_CHAOS)
		return (0);
#endif

	hash = cache_hash(ReplyCache, t->qtype, t->qd, t->qdlen);
	ReplyCache->questions++;

	/* Look at the appropriate node.  Descend list and find match. */
	for (n = ReplyCache->nodes[hash]; n; n = n->next_node)
	{
		if ((n->namelen == t->qdlen) && (n->type == t->qtype) && (n->protocol == t->protocol))
		{
			if (!n->name)
				Errx(_("reply cache node %p at hash %u has NULL name"), n, hash);
			if (!memcmp(n->name, t->qd, t->qdlen))
			{
				/* Is the node expired? */
				if (n->expire && (current_time > n->expire))
				{
					cache_free_node(ReplyCache, hash, n);
					break;
				}

				/* Found in cache; move to head of usefulness list */
				mrulist_del(ReplyCache, n);
				mrulist_add(ReplyCache, n);

				/* Allocate space for reply data */
				t->replylen = n->datalen - sizeof(DNS_HEADER) - sizeof(task_error_t);
				if (!(t->reply = malloc(t->replylen)))
					Err(_("out of memory"));
				p = n->data;

				/* Copy DNS header */
				memcpy(&t->hdr, p, sizeof(DNS_HEADER));
				p += sizeof(DNS_HEADER);

				/* Copy reason */
				memcpy(&t->reason, p, sizeof(task_error_t));
				p += sizeof(task_error_t);

				/* Copy reply data */
				memcpy(t->reply, p, t->replylen);

				/* Set count of records in each section */
				p = t->reply + SIZE16 + SIZE16 + SIZE16;
				DNS_GET16(t->an.size, p);
				DNS_GET16(t->ns.size, p);
				DNS_GET16(t->ar.size, p);

				t->zone = n->zone;

				t->reply_from_cache = 1;
				ReplyCache->hits++;
#if DEBUG_ENABLED && DEBUG_CACHE
				Debug(_("%s: %d octet reply found in cache"), desctask(t), t->replylen);
#endif

				return (1);
			}
		}
	}
	ReplyCache->misses++;
	return (0);
}
/*--- reply_cache_find() ------------------------------------------------------------------------*/


/**************************************************************************************************
	ADD_REPLY_TO_CACHE
	Adds the current reply to the reply cache.
**************************************************************************************************/
void
add_reply_to_cache(TASK *t)
{
	register uint32_t	hash;
	register CNODE		*n;
	register void		*p;

#if DEBUG_ENABLED && DEBUG_CACHE
	Debug("%s: add_reply_to_cache(qdlen=%d rcode=%s rd=%d proto=%d)", desctask(t),
			t->qdlen, mydns_rcode_str(t->hdr.rcode), t->hdr.rd, t->protocol);
#endif

	if (!ReplyCache || t->qdlen > DNS_MAXPACKETLEN_UDP || t->hdr.rcode == DNS_RCODE_SERVFAIL)
	{
#if DEBUG_ENABLED && DEBUG_CACHE
		Debug("reply should not be cached");
#endif
		return;
	}

	/* Don't cache replies from recursive forwarder */
	if (t->forwarded)
		return;

#if STATUS_ENABLED
	/* Don't cache status requests */
	if (t->qclass == DNS_CLASS_CHAOS)
		return;
#endif

	/* Don't cache negative replies if recursive forwarding is enabled */
	if (forward_recursive && t->hdr.rcode != DNS_RCODE_NOERROR)
		return;

	hash = cache_hash(ReplyCache, t->qtype, t->qd, t->qdlen);

	/* Look at the appropriate node.  Descend list and find match. */
	for (n = ReplyCache->nodes[hash]; n; n = n->next_node)
	{
		if ((n->namelen == t->qdlen) && (n->type == t->qtype) && (n->protocol == t->protocol))
		{
			if (!n->name)
				Errx(_("reply cache node %p at hash %u has NULL name"), n, hash);

			if (!memcmp(n->name, t->qd, t->qdlen))
			{
				/* Is the node expired? */
				if (n->expire && (current_time > n->expire))
				{
					cache_free_node(ReplyCache, hash, n);
					break;
				}

				/* Found in cache; move to head of usefulness list */
				mrulist_del(ReplyCache, n);
				mrulist_add(ReplyCache, n);
				return;
			}
		}
	}

	/* If the cache is full, delete the least recently used node and add new node */
	if (ReplyCache->count >= ReplyCache->limit)
	{
		if (ReplyCache->mruTail)
		{
			ReplyCache->removed++;
			ReplyCache->removed_secs += current_time - ReplyCache->mruTail->insert_time;
			cache_free_node(ReplyCache, ReplyCache->mruTail->hash, ReplyCache->mruTail);
		}
		else
			return;
	}

	/* Add to cache */
	ReplyCache->in++;

	if (!(n = calloc(1, sizeof(CNODE))))
		Err(_("out of memory"));
	n->hash = hash;
	n->zone = t->zone;
	n->type = t->qtype;
	n->protocol = t->protocol;
	memcpy(n->name, t->qd, t->qdlen);
	n->namelen = t->qdlen;

	/* The data is the DNS_HEADER, the reason, then the reply */
	n->datalen = sizeof(DNS_HEADER) + sizeof(task_error_t) + t->replylen;
	if (!(n->data = malloc(n->datalen)))
		Err(_("out of memory"));
	p = n->data;

	/* Save DNS header */
	memcpy(p, &t->hdr, sizeof(DNS_HEADER));
	p += sizeof(DNS_HEADER);

	/* Save reason for error, if any */
	memcpy(p, &t->reason, sizeof(task_error_t));
	p += sizeof(task_error_t);

	/* Save reply data */
	memcpy(p, t->reply, t->replylen);

	n->insert_time = current_time;
	if (ReplyCache->expire)
		n->expire = current_time + ReplyCache->expire;
	n->next_node = ReplyCache->nodes[hash];

	/* Add node to cache */
	ReplyCache->nodes[hash] = n;
	ReplyCache->count++;

	/* Add node to head of MRU list */
	mrulist_add(ReplyCache, n);

#if DEBUG_ENABLED && DEBUG_CACHE
	Debug("%s: %s (qtype=%s qdlen=%d rd=%d proto=%d)", desctask(t), _("reply cached"),
			mydns_qtype_str(t->qtype), t->qdlen, t->hdr.rd, t->protocol);
#endif
}
/*--- add_reply_to_cache() ----------------------------------------------------------------------*/

/* vi:set ts=3: */
/* NEED_PO */