/*
 * services/cache/rrset.c - 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.
 */
#include "config.h"
#include "services/cache/rrset.h"
#include "sldns/rrdef.h"
#include "util/storage/slabhash.h"
#include "util/config_file.h"
#include "util/data/packed_rrset.h"
#include "util/data/msgreply.h"
#include "util/data/msgparse.h"
#include "util/data/dname.h"
#include "util/regional.h"
#include "util/alloc.h"
#include "util/net_help.h"

void
rrset_markdel(void* key)
{
        struct ub_packed_rrset_key* r = (struct ub_packed_rrset_key*)key;
        r->id = 0;
}

struct rrset_cache* rrset_cache_create(struct config_file* cfg, 
        struct alloc_cache* alloc)
{
        size_t slabs = (cfg?cfg->rrset_cache_slabs:HASH_DEFAULT_SLABS);
        size_t startarray = HASH_DEFAULT_STARTARRAY;
        size_t maxmem = (cfg?cfg->rrset_cache_size:HASH_DEFAULT_MAXMEM);

        struct rrset_cache *r = (struct rrset_cache*)slabhash_create(slabs,
                startarray, maxmem, ub_rrset_sizefunc, ub_rrset_compare,
                ub_rrset_key_delete, rrset_data_delete, alloc);
        if(!r)
                return NULL;
        slabhash_setmarkdel(&r->table, &rrset_markdel);
        return r;
}

void rrset_cache_delete(struct rrset_cache* r)
{
        if(!r) 
                return;
        slabhash_delete(&r->table);
        /* slabhash delete also does free(r), since table is first in struct*/
}

struct rrset_cache* rrset_cache_adjust(struct rrset_cache *r, 
        struct config_file* cfg, struct alloc_cache* alloc)
{
        if(!r || !cfg || !slabhash_is_size(&r->table, cfg->rrset_cache_size,
                cfg->rrset_cache_slabs))
        {
                rrset_cache_delete(r);
                r = rrset_cache_create(cfg, alloc);
        }
        return r;
}

void 
rrset_cache_touch(struct rrset_cache* r, struct ub_packed_rrset_key* key,
        hashvalue_type hash, rrset_id_type id)
{
        struct lruhash* table = slabhash_gettable(&r->table, hash);
        /* 
         * This leads to locking problems, deadlocks, if the caller is 
         * holding any other rrset lock.
         * Because a lookup through the hashtable does:
         *      tablelock -> entrylock  (for that entry caller holds)
         * And this would do
         *      entrylock(already held) -> tablelock
         * And if two threads do this, it results in deadlock.
         * So, the caller must not hold entrylock.
         */
        lock_quick_lock(&table->lock);
        /* we have locked the hash table, the item can still be deleted.
         * because it could already have been reclaimed, but not yet set id=0.
         * This is because some lruhash routines have lazy deletion.
         * so, we must acquire a lock on the item to verify the id != 0.
         * also, with hash not changed, we are using the right slab.
         */
        lock_rw_rdlock(&key->entry.lock);
        if(key->id == id && key->entry.hash == hash) {
                lru_touch(table, &key->entry);
        }
        lock_rw_unlock(&key->entry.lock);
        lock_quick_unlock(&table->lock);
}

/** see if rrset needs to be updated in the cache */
static int
need_to_update_rrset(void* nd, void* cd, time_t timenow, int equal, int ns)
{
        struct packed_rrset_data* newd = (struct packed_rrset_data*)nd;
        struct packed_rrset_data* cached = (struct packed_rrset_data*)cd;
        /*      o if new data is expired, cached data is better */
        if( newd->ttl < timenow && timenow <= cached->ttl)
                return 0;
        /*      o store if rrset has been validated 
         *              everything better than bogus data 
         *              secure is preferred */
        if( newd->security == sec_status_secure &&
                cached->security != sec_status_secure)
                return 1;
        if( cached->security == sec_status_bogus && 
                newd->security != sec_status_bogus && !equal)
                return 1;
        /*      o if new RRset is more trustworthy - insert it */
        if( newd->trust > cached->trust ) {
                /* if the cached rrset is bogus, and new is equal,
                 * do not update the TTL - let it expire. */
                if(equal && cached->ttl >= timenow && 
                        cached->security == sec_status_bogus)
                        return 0;
                return 1;
        }
        /*      o item in cache has expired */
        if( cached->ttl < timenow )
                return 1;
        /*  o same trust, but different in data - insert it */
        if( newd->trust == cached->trust && !equal ) {
                /* if this is type NS, do not 'stick' to owner that changes
                 * the NS RRset, but use the cached TTL for the new data, and
                 * update to fetch the latest data. ttl is not expired, because
                 * that check was before this one. */
                if(ns) {
                        size_t i;
                        newd->ttl = cached->ttl;
                        for(i=0; i<(newd->count+newd->rrsig_count); i++)
                                if(newd->rr_ttl[i] > newd->ttl)
                                        newd->rr_ttl[i] = newd->ttl;
                }
                return 1;
        }
        return 0;
}

/** Update RRSet special key ID */
static void
rrset_update_id(struct rrset_ref* ref, struct alloc_cache* alloc)
{
        /* this may clear the cache and invalidate lock below */
        uint64_t newid = alloc_get_id(alloc);
        /* obtain writelock */
        lock_rw_wrlock(&ref->key->entry.lock);
        /* check if it was deleted in the meantime, if so, skip update */
        if(ref->key->id == ref->id) {
                ref->key->id = newid;
                ref->id = newid;
        }
        lock_rw_unlock(&ref->key->entry.lock);
}

int 
rrset_cache_update(struct rrset_cache* r, struct rrset_ref* ref,
        struct alloc_cache* alloc, time_t timenow)
{
        struct lruhash_entry* e;
        struct ub_packed_rrset_key* k = ref->key;
        hashvalue_type h = k->entry.hash;
        uint16_t rrset_type = ntohs(k->rk.type);
        int equal = 0;
        log_assert(ref->id != 0 && k->id != 0);
        log_assert(k->rk.dname != NULL);
        /* looks up item with a readlock - no editing! */
        if((e=slabhash_lookup(&r->table, h, k, 0)) != 0) {
                /* return id and key as they will be used in the cache
                 * since the lruhash_insert, if item already exists, deallocs
                 * the passed key in favor of the already stored key.
                 * because of the small gap (see below) this key ptr and id
                 * may prove later to be already deleted, which is no problem
                 * as it only makes a cache miss. 
                 */
                ref->key = (struct ub_packed_rrset_key*)e->key;
                ref->id = ref->key->id;
                equal = rrsetdata_equal((struct packed_rrset_data*)k->entry.
                        data, (struct packed_rrset_data*)e->data);
                if(!need_to_update_rrset(k->entry.data, e->data, timenow,
                        equal, (rrset_type==LDNS_RR_TYPE_NS))) {
                        /* cache is superior, return that value */
                        lock_rw_unlock(&e->lock);
                        ub_packed_rrset_parsedelete(k, alloc);
                        if(equal) return 2;
                        return 1;
                }
                lock_rw_unlock(&e->lock);
                /* Go on and insert the passed item.
                 * small gap here, where entry is not locked.
                 * possibly entry is updated with something else.
                 * we then overwrite that with our data.
                 * this is just too bad, its cache anyway. */
                /* use insert to update entry to manage lruhash
                 * cache size values nicely. */
        }
        log_assert(ref->key->id != 0);
        slabhash_insert(&r->table, h, &k->entry, k->entry.data, alloc);
        if(e) {
                /* For NSEC, NSEC3, DNAME, when rdata is updated, update 
                 * the ID number so that proofs in message cache are 
                 * invalidated */
                if((rrset_type == LDNS_RR_TYPE_NSEC 
                        || rrset_type == LDNS_RR_TYPE_NSEC3
                        || rrset_type == LDNS_RR_TYPE_DNAME) && !equal) {
                        rrset_update_id(ref, alloc);
                }
                return 1;
        }
        return 0;
}

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)
{
        struct rrset_ref ref;
        uint8_t wc_dname[LDNS_MAX_DOMAINLEN+3];
        rrset = packed_rrset_copy_alloc(rrset, alloc, timenow);
        if(!rrset) {
                log_err("malloc failure in rrset_cache_update_wildcard");
                return;
        }
        /* ce has at least one label less then qname, we can therefore safely
         * add the wildcard label. */
        wc_dname[0] = 1;
        wc_dname[1] = (uint8_t)'*';
        memmove(wc_dname+2, ce, ce_len);

        free(rrset->rk.dname);
        rrset->rk.dname_len = ce_len + 2;
        rrset->rk.dname = (uint8_t*)memdup(wc_dname, rrset->rk.dname_len);
        if(!rrset->rk.dname) {
                alloc_special_release(alloc, rrset);
                log_err("memdup failure in rrset_cache_update_wildcard");
                return;
        }

        rrset->entry.hash = rrset_key_hash(&rrset->rk);
        ref.key = rrset;
        ref.id = rrset->id;
        /* ignore ret: if it was in the cache, ref updated */
        (void)rrset_cache_update(rrset_cache, &ref, alloc, timenow);
}

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)
{
        struct lruhash_entry* e;
        struct ub_packed_rrset_key key;
        
        key.entry.key = &key;
        key.entry.data = NULL;
        key.rk.dname = qname;
        key.rk.dname_len = qnamelen;
        key.rk.type = htons(qtype);
        key.rk.rrset_class = htons(qclass);
        key.rk.flags = flags;

        key.entry.hash = rrset_key_hash(&key.rk);

        if((e = slabhash_lookup(&r->table, key.entry.hash, &key, wr))) {
                /* check TTL */
                struct packed_rrset_data* data = 
                        (struct packed_rrset_data*)e->data;
                if(timenow > data->ttl) {
                        lock_rw_unlock(&e->lock);
                        return NULL;
                }
                /* we're done */
                return (struct ub_packed_rrset_key*)e->key;
        }
        return NULL;
}

int 
rrset_array_lock(struct rrset_ref* ref, size_t count, time_t timenow)
{
        size_t i;
        for(i=0; i<count; i++) {
                if(i>0 && ref[i].key == ref[i-1].key)
                        continue; /* only lock items once */
                lock_rw_rdlock(&ref[i].key->entry.lock);
                if(ref[i].id != ref[i].key->id || timenow >
                        ((struct packed_rrset_data*)(ref[i].key->entry.data))
                        ->ttl) {
                        /* failure! rollback our readlocks */
                        rrset_array_unlock(ref, i+1);
                        return 0;
                }
        }
        return 1;
}

void 
rrset_array_unlock(struct rrset_ref* ref, size_t count)
{
        size_t i;
        for(i=0; i<count; i++) {
                if(i>0 && ref[i].key == ref[i-1].key)
                        continue; /* only unlock items once */
                lock_rw_unlock(&ref[i].key->entry.lock);
        }
}

void 
rrset_array_unlock_touch(struct rrset_cache* r, struct regional* scratch,
        struct rrset_ref* ref, size_t count)
{
        hashvalue_type* h;
        size_t i;
        if(count > RR_COUNT_MAX || !(h = (hashvalue_type*)regional_alloc(
                scratch, sizeof(hashvalue_type)*count))) {
                log_warn("rrset LRU: memory allocation failed");
                h = NULL;
        } else  /* store hash values */
                for(i=0; i<count; i++)
                        h[i] = ref[i].key->entry.hash;
        /* unlock */
        for(i=0; i<count; i++) {
                if(i>0 && ref[i].key == ref[i-1].key)
                        continue; /* only unlock items once */
                lock_rw_unlock(&ref[i].key->entry.lock);
        }
        if(h) {
                /* LRU touch, with no rrset locks held */
                for(i=0; i<count; i++) {
                        if(i>0 && ref[i].key == ref[i-1].key)
                                continue; /* only touch items once */
                        rrset_cache_touch(r, ref[i].key, h[i], ref[i].id);
                }
        }
}

void 
rrset_update_sec_status(struct rrset_cache* r, 
        struct ub_packed_rrset_key* rrset, time_t now)
{
        struct packed_rrset_data* updata = 
                (struct packed_rrset_data*)rrset->entry.data;
        struct lruhash_entry* e;
        struct packed_rrset_data* cachedata;

        /* hash it again to make sure it has a hash */
        rrset->entry.hash = rrset_key_hash(&rrset->rk);

        e = slabhash_lookup(&r->table, rrset->entry.hash, rrset, 1);
        if(!e)
                return; /* not in the cache anymore */
        cachedata = (struct packed_rrset_data*)e->data;
        if(!rrsetdata_equal(updata, cachedata)) {
                lock_rw_unlock(&e->lock);
                return; /* rrset has changed in the meantime */
        }
        /* update the cached rrset */
        if(updata->security > cachedata->security) {
                size_t i;
                if(updata->trust > cachedata->trust)
                        cachedata->trust = updata->trust;
                cachedata->security = updata->security;
                /* for NS records only shorter TTLs, other types: update it */
                if(ntohs(rrset->rk.type) != LDNS_RR_TYPE_NS ||
                        updata->ttl+now < cachedata->ttl ||
                        cachedata->ttl < now ||
                        updata->security == sec_status_bogus) {
                        cachedata->ttl = updata->ttl + now;
                        for(i=0; i<cachedata->count+cachedata->rrsig_count; i++)
                                cachedata->rr_ttl[i] = updata->rr_ttl[i]+now;
                        cachedata->ttl_add = now;
                }
        }
        lock_rw_unlock(&e->lock);
}

void 
rrset_check_sec_status(struct rrset_cache* r, 
        struct ub_packed_rrset_key* rrset, time_t now)
{
        struct packed_rrset_data* updata = 
                (struct packed_rrset_data*)rrset->entry.data;
        struct lruhash_entry* e;
        struct packed_rrset_data* cachedata;

        /* hash it again to make sure it has a hash */
        rrset->entry.hash = rrset_key_hash(&rrset->rk);

        e = slabhash_lookup(&r->table, rrset->entry.hash, rrset, 0);
        if(!e)
                return; /* not in the cache anymore */
        cachedata = (struct packed_rrset_data*)e->data;
        if(now > cachedata->ttl || !rrsetdata_equal(updata, cachedata)) {
                lock_rw_unlock(&e->lock);
                return; /* expired, or rrset has changed in the meantime */
        }
        if(cachedata->security > updata->security) {
                updata->security = cachedata->security;
                if(cachedata->security == sec_status_bogus) {
                        size_t i;
                        updata->ttl = cachedata->ttl - now;
                        for(i=0; i<cachedata->count+cachedata->rrsig_count; i++)
                                if(cachedata->rr_ttl[i] < now)
                                        updata->rr_ttl[i] = 0;
                                else updata->rr_ttl[i] = 
                                        cachedata->rr_ttl[i]-now;
                }
                if(cachedata->trust > updata->trust)
                        updata->trust = cachedata->trust;
        }
        lock_rw_unlock(&e->lock);
}

void
rrset_cache_remove_above(struct rrset_cache* r, uint8_t** qname, size_t*
        qnamelen, uint16_t searchtype, uint16_t qclass, time_t now, uint8_t*
        qnametop, size_t qnametoplen)
{
        struct ub_packed_rrset_key *rrset;
        uint8_t lablen;

        while(*qnamelen > 0) {
                /* look one label higher */
                lablen = **qname;
                *qname += lablen + 1;
                *qnamelen -= lablen + 1;
                if(*qnamelen <= 0)
                        return;

                /* stop at qnametop */
                if(qnametop && *qnamelen == qnametoplen &&
                        query_dname_compare(*qname, qnametop)==0)
                        return;

                if(verbosity >= VERB_ALGO) {
                        /* looks up with a time of 0, to see expired entries */
                        if((rrset = rrset_cache_lookup(r, *qname,
                                *qnamelen, searchtype, qclass, 0, 0, 0))) {
                                struct packed_rrset_data* data =
                                        (struct packed_rrset_data*)rrset->entry.data;
                                int expired = (now > data->ttl);
                                lock_rw_unlock(&rrset->entry.lock);
                                if(expired)
                                        log_nametypeclass(verbosity, "this "
                                                "(grand)parent rrset will be "
                                                "removed (expired)",
                                                *qname, searchtype, qclass);
                                else    log_nametypeclass(verbosity, "this "
                                                "(grand)parent rrset will be "
                                                "removed",
                                                *qname, searchtype, qclass);
                        }
                }
                rrset_cache_remove(r, *qname, *qnamelen, searchtype, qclass, 0);
        }
}

int
rrset_cache_expired_above(struct rrset_cache* r, uint8_t** qname, size_t*
        qnamelen, uint16_t searchtype, uint16_t qclass, time_t now, uint8_t*
        qnametop, size_t qnametoplen)
{
        struct ub_packed_rrset_key *rrset;
        uint8_t lablen;

        while(*qnamelen > 0) {
                /* look one label higher */
                lablen = **qname;
                *qname += lablen + 1;
                *qnamelen -= lablen + 1;
                if(*qnamelen <= 0)
                        break;

                /* looks up with a time of 0, to see expired entries */
                if((rrset = rrset_cache_lookup(r, *qname,
                        *qnamelen, searchtype, qclass, 0, 0, 0))) {
                        struct packed_rrset_data* data =
                                (struct packed_rrset_data*)rrset->entry.data;
                        if(now > data->ttl) {
                                /* it is expired, this is not wanted */
                                lock_rw_unlock(&rrset->entry.lock);
                                log_nametypeclass(VERB_ALGO, "this rrset is expired", *qname, searchtype, qclass);
                                return 1;
                        }
                        /* it is not expired, continue looking */
                        lock_rw_unlock(&rrset->entry.lock);
                }

                /* do not look above the qnametop. */
                if(qnametop && *qnamelen == qnametoplen &&
                        query_dname_compare(*qname, qnametop)==0)
                        break;
        }
        return 0;
}

void rrset_cache_remove(struct rrset_cache* r, uint8_t* nm, size_t nmlen,
        uint16_t type, uint16_t dclass, uint32_t flags)
{
        struct ub_packed_rrset_key key;
        key.entry.key = &key;
        key.rk.dname = nm;
        key.rk.dname_len = nmlen;
        key.rk.rrset_class = htons(dclass);
        key.rk.type = htons(type);
        key.rk.flags = flags;
        key.entry.hash = rrset_key_hash(&key.rk);
        slabhash_remove(&r->table, key.entry.hash, &key);
}