text: /*
   * services/cache/rrset.h - Resource record set cache.
   *
   * Copyright (c) 2007, NLnet Labs. All rights reserved.
   *
   * This software is open source.
   * 
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 
   * Redistributions of source code must retain the above copyright notice,
   * this list of conditions and the following disclaimer.
   * 
   * Redistributions in binary form must reproduce the above copyright notice,
   * this list of conditions and the following disclaimer in the documentation
   * and/or other materials provided with the distribution.
   * 
   * Neither the name of the NLNET LABS nor the names of its contributors may
   * be used to endorse or promote products derived from this software without
   * specific prior written permission.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
   * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  /**
   * \file
   *
   * This file contains the rrset cache.
   */
  
  #ifndef SERVICES_CACHE_RRSET_H
  #define SERVICES_CACHE_RRSET_H
  #include "util/storage/lruhash.h"
  #include "util/storage/slabhash.h"
  #include "util/data/packed_rrset.h"
  struct config_file;
  struct alloc_cache;
  struct rrset_ref;
  struct regional;
  
  /**
   * The rrset cache
   * Thin wrapper around hashtable, like a typedef.
   */
  struct rrset_cache {
  	/** uses partitioned hash table */
  	struct slabhash table;
  };
  
  /**
   * Create rrset cache
   * @param cfg: config settings or NULL for defaults.
   * @param alloc: initial default rrset key allocation.
   * @return: NULL on error.
   */
  struct rrset_cache* rrset_cache_create(struct config_file* cfg, 
  	struct alloc_cache* alloc);
  
  /**
   * Delete rrset cache
   * @param r: rrset cache to delete.
   */
  void rrset_cache_delete(struct rrset_cache* r);
  
  /**
   * Adjust settings of the cache to settings from the config file.
   * May purge the cache. May recreate the cache.
   * There may be no threading or use by other threads.
   * @param r: rrset cache to adjust (like realloc).
   * @param cfg: config settings or NULL for defaults.
   * @param alloc: initial default rrset key allocation.
   * @return 0 on error, or new rrset cache pointer on success.
   */
  struct rrset_cache* rrset_cache_adjust(struct rrset_cache* r, 
  	struct config_file* cfg, struct alloc_cache* alloc);
  
  /**
   * Touch rrset, with given pointer and id.
   * Caller may not hold a lock on ANY rrset, this could give deadlock.
   *
   * This routine is faster than a hashtable lookup:
   *	o no bin_lock is acquired.
   *	o no walk through the bin-overflow-list. 
   *	o no comparison of the entry key to find it.
   *
   * @param r: rrset cache.
   * @param key: rrset key. Marked recently used (if it was not deleted
   *	before the lock is acquired, in that case nothing happens).
   * @param hash: hash value of the item. Please read it from the key when
   *	you have it locked. Used to find slab from slabhash.
   * @param id: used to check that the item is unchanged and not deleted.
   */
  void rrset_cache_touch(struct rrset_cache* r, struct ub_packed_rrset_key* key,
  	hashvalue_type hash, rrset_id_type id);
  
  /**
   * Update an rrset in the rrset cache. Stores the information for later use.
   * Will lookup if the rrset is in the cache and perform an update if necessary.
   * If the item was present, and superior, references are returned to that.
   * The passed item is then deallocated with rrset_parsedelete.
   *
   * A superior rrset is:
   *	o rrset with better trust value.
   *	o same trust value, different rdata, newly passed rrset is inserted.
   * If rdata is the same, TTL in the cache is updated.
   *
   * @param r: the rrset cache.
   * @param ref: reference (ptr and id) to the rrset. Pass reference setup for
   *	the new rrset. The reference may be changed if the cached rrset is
   *	superior.
   *	Before calling the rrset is presumed newly allocated and changeable.
   *	Afer calling you do not hold a lock, and the rrset is inserted in
   *	the hashtable so you need a lock to change it.
   * @param alloc: how to allocate (and deallocate) the special rrset key.
   * @param timenow: current time (to see if ttl in cache is expired).
   * @return: true if the passed reference is updated, false if it is unchanged.
   * 	0: reference unchanged, inserted in cache.
   * 	1: reference updated, item is inserted in cache.
   * 	2: reference updated, item in cache is considered superior.
   *	   also the rdata is equal (but other parameters in cache are superior).
   */
  int rrset_cache_update(struct rrset_cache* r, struct rrset_ref* ref, 
  	struct alloc_cache* alloc, time_t timenow);
  
  /**
   * Update or add an rrset in the rrset cache using a wildcard dname.
   * Generates wildcard dname by prepending the wildcard label to the closest
   * encloser. Will lookup if the rrset is in the cache and perform an update if
   * necessary.
   *
   * @param rrset_cache: the rrset cache.
   * @param rrset: which rrset to cache as wildcard. This rrset is left 
   * 	untouched.
   * @param ce: the closest encloser, will be uses to generate the wildcard dname.
   * @param ce_len: the closest encloser lenght.
   * @param alloc: how to allocate (and deallocate) the special rrset key.
   * @param timenow: current time (to see if ttl in cache is expired).
   */
  void rrset_cache_update_wildcard(struct rrset_cache* rrset_cache, 
  	struct ub_packed_rrset_key* rrset, uint8_t* ce, size_t ce_len,
  	struct alloc_cache* alloc, time_t timenow);
  
  /**
   * Lookup rrset. You obtain read/write lock. You must unlock before lookup
   * anything of else.
   * @param r: the rrset cache.
   * @param qname: name of rrset to lookup.
   * @param qnamelen: length of name of rrset to lookup.
   * @param qtype: type of rrset to lookup (host order).
   * @param qclass: class of rrset to lookup (host order).
   * @param flags: rrset flags, or 0.
   * @param timenow: used to compare with TTL.
   * @param wr: set true to get writelock.
   * @return packed rrset key pointer. Remember to unlock the key.entry.lock.
   * 	or NULL if could not be found or it was timed out.
   */
  struct ub_packed_rrset_key* rrset_cache_lookup(struct rrset_cache* r,
  	uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass,
  	uint32_t flags, time_t timenow, int wr);
  
  /**
   * Obtain readlock on a (sorted) list of rrset references.
   * Checks TTLs and IDs of the rrsets and rollbacks locking if not Ok.
   * @param ref: array of rrset references (key pointer and ID value).
   *	duplicate references are allowed and handled.
   * @param count: size of array.
   * @param timenow: used to compare with TTL.
   * @return true on success, false on a failure, which can be that some
   * 	RRsets have timed out, or that they do not exist any more, the
   *	RRsets have been purged from the cache.
   *	If true, you hold readlocks on all the ref items. 
   */
  int rrset_array_lock(struct rrset_ref* ref, size_t count, time_t timenow);
  
  /**
   * Unlock array (sorted) of rrset references.
   * @param ref: array of rrset references (key pointer and ID value).
   *	duplicate references are allowed and handled.
   * @param count: size of array.
   */
  void rrset_array_unlock(struct rrset_ref* ref, size_t count);
  
  /**
   * Unlock array (sorted) of rrset references and at the same time
   * touch LRU on the rrsets. It needs the scratch region for temporary
   * storage as it uses the initial locks to obtain hash values.
   * @param r: the rrset cache. In this cache LRU is updated.
   * @param scratch: region for temporary storage of hash values.
   *	if memory allocation fails, the lru touch fails silently,
   *	but locks are released. memory errors are logged.
   * @param ref: array of rrset references (key pointer and ID value).
   *	duplicate references are allowed and handled.
   * @param count: size of array.
   */
  void rrset_array_unlock_touch(struct rrset_cache* r, struct regional* scratch,
  	struct rrset_ref* ref, size_t count);
  
  /**
   * Update security status of an rrset. Looks up the rrset.
   * If found, checks if rdata is equal.
   * If so, it will update the security, trust and rrset-ttl values.
   * The values are only updated if security is increased (towards secure).
   * @param r: the rrset cache. 
   * @param rrset: which rrset to attempt to update. This rrset is left 
   * 	untouched. The rrset in the cache is updated in-place.
   * @param now: current time.
   */
  void rrset_update_sec_status(struct rrset_cache* r, 
  	struct ub_packed_rrset_key* rrset, time_t now);
  
  /**
   * Looks up security status of an rrset. Looks up the rrset.
   * If found, checks if rdata is equal, and entry did not expire.
   * If so, it will update the security, trust and rrset-ttl values.
   * @param r: the rrset cache. 
   * @param rrset: This rrset may change security status due to the cache.
   * 	But its status will only improve, towards secure.
   * @param now: current time.
   */
  void rrset_check_sec_status(struct rrset_cache* r, 
  	struct ub_packed_rrset_key* rrset, time_t now);
  
  /**
   * Remove an rrset from the cache, by name and type and flags
   * @param r: rrset cache
   * @param nm: name of rrset
   * @param nmlen: length of name
   * @param type: type of rrset
   * @param dclass: class of rrset, host order
   * @param flags: flags of rrset, host order
   */
  void rrset_cache_remove(struct rrset_cache* r, uint8_t* nm, size_t nmlen,
  	uint16_t type, uint16_t dclass, uint32_t flags);
  
  /** mark rrset to be deleted, set id=0 */
  void rrset_markdel(void* key);
  
  #endif /* SERVICES_CACHE_RRSET_H */
  