/*

 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")

 *

 * SPDX-License-Identifier: MPL-2.0

 *

 * This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, you can obtain one at https://mozilla.org/MPL/2.0/.

 *

 * See the COPYRIGHT file distributed with this work for additional

 * information regarding copyright ownership.

 */

/*! \file */

#include <inttypes.h>

#include <stdbool.h>

#include <isc/log.h>

#include <isc/loop.h>

#include <isc/mem.h>

#include <isc/refcount.h>

#include <isc/result.h>

#include <isc/stats.h>

#include <isc/string.h>

#include <isc/time.h>

#include <isc/timer.h>

#include <isc/util.h>

#include <dns/cache.h>

#include <dns/db.h>

#include <dns/dbiterator.h>

#include <dns/masterdump.h>

#include <dns/rdata.h>

#include <dns/rdataset.h>

#include <dns/rdatasetiter.h>

#include <dns/stats.h>

#ifdef HAVE_JSON_C

#include <json_object.h>

#endif /* HAVE_JSON_C */

#ifdef HAVE_LIBXML2

#include <libxml/xmlwriter.h>

#define ISC_XMLCHAR (const xmlChar *)

#endif /* HAVE_LIBXML2 */

#define CACHE_MAGIC    ISC_MAGIC('$', '$', '$', '$')

#define VALID_CACHE(cache) ISC_MAGIC_VALID(cache, CACHE_MAGIC)

/***

 ***  Types

 ***/

/*%

 * The actual cache object.

 */

struct dns_cache {

  /* Unlocked. */

  unsigned int magic;

  isc_mutex_t lock;

  isc_mem_t *mctx;  /* Memory context for the dns_cache object */

  isc_mem_t *tmctx; /* Tree memory */

  char *name;

  isc_refcount_t references;

  /* Locked by 'lock'. */

  dns_rdataclass_t rdclass;

  dns_db_t *db;

  size_t size;

  dns_ttl_t serve_stale_ttl;

  dns_ttl_t serve_stale_refresh;

  isc_stats_t *stats;

  uint32_t maxrrperset;

  uint32_t maxtypepername;

};

/***

 ***  Functions

 ***/

static isc_result_t

cache_create_db(dns_cache_t *cache, dns_db_t **dbp, isc_mem_t **tmctxp) {

  isc_result_t result;

  dns_db_t *db = NULL;

  isc_mem_t *tmctx = NULL;

  /*

   * This will be the cache memory context, which is subject

   * to cleaning when the configured memory limits are exceeded.

   */

  isc_mem_create("cache", &tmctx);

  result = dns_db_create(tmctx, CACHEDB_DEFAULT, dns_rootname,

             dns_dbtype_cache, cache->rdclass, 0, NULL, &db);

  if (result != ISC_R_SUCCESS) {

    goto cleanup_mctx;

  }

  result = dns_db_setcachestats(db, cache->stats);

  if (result != ISC_R_SUCCESS) {

    goto cleanup_db;

  }

  dns_db_setservestalettl(db, cache->serve_stale_ttl);

  dns_db_setservestalerefresh(db, cache->serve_stale_refresh);

  dns_db_setmaxrrperset(db, cache->maxrrperset);

  dns_db_setmaxtypepername(db, cache->maxtypepername);

  *dbp = db;

  *tmctxp = tmctx;

  return ISC_R_SUCCESS;

cleanup_db:

  dns_db_detach(&db);

cleanup_mctx:

  isc_mem_detach(&tmctx);

  return result;

}

static void

cache_destroy(dns_cache_t *cache) {

  isc_stats_detach(&cache->stats);

  isc_mutex_destroy(&cache->lock);

  isc_mem_free(cache->mctx, cache->name);

  if (cache->tmctx != NULL) {

    isc_mem_detach(&cache->tmctx);

  }

  isc_mem_putanddetach(&cache->mctx, cache, sizeof(*cache));

}

isc_result_t

dns_cache_create(dns_rdataclass_t rdclass, const char *cachename,

     isc_mem_t *mctx, dns_cache_t **cachep) {

  isc_result_t result;

  dns_cache_t *cache = NULL;

  REQUIRE(cachename != NULL);

  REQUIRE(cachep != NULL && *cachep == NULL);

  cache = isc_mem_get(mctx, sizeof(*cache));

  *cache = (dns_cache_t){

    .rdclass = rdclass,

    .name = isc_mem_strdup(mctx, cachename),

    .references = ISC_REFCOUNT_INITIALIZER(1),

    .magic = CACHE_MAGIC,

  };

  isc_mutex_init(&cache->lock);

  isc_mem_attach(mctx, &cache->mctx);

  isc_stats_create(mctx, &cache->stats, dns_cachestatscounter_max);

  /*

   * Create the database

   */

  CHECK(cache_create_db(cache, &cache->db, &cache->tmctx));

  *cachep = cache;

  return ISC_R_SUCCESS;

cleanup:

  cache_destroy(cache);

  return result;

}

static void

cache_cleanup(dns_cache_t *cache) {

  REQUIRE(VALID_CACHE(cache));

  isc_refcount_destroy(&cache->references);

  cache->magic = 0;

  isc_mem_clearwater(cache->tmctx);

  dns_db_detach(&cache->db);

  cache_destroy(cache);

}

#if DNS_CACHE_TRACE

ISC_REFCOUNT_TRACE_IMPL(dns_cache, cache_cleanup);

#else

ISC_REFCOUNT_IMPL(dns_cache, cache_cleanup);

Unexecuted instantiation: dns_cache_ref

Unexecuted instantiation: dns_cache_unref

Unexecuted instantiation: dns_cache_detach

#endif

void

dns_cache_attachdb(dns_cache_t *cache, dns_db_t **dbp) {

  REQUIRE(VALID_CACHE(cache));

  REQUIRE(dbp != NULL && *dbp == NULL);

  REQUIRE(cache->db != NULL);

  LOCK(&cache->lock);

  dns_db_attach(cache->db, dbp);

  UNLOCK(&cache->lock);

}

const char *

dns_cache_getname(dns_cache_t *cache) {

  REQUIRE(VALID_CACHE(cache));

  return cache->name;

}

static void

updatewater(dns_cache_t *cache) {

  size_t hi = cache->size - (cache->size >> 3); /* ~ 7/8ths. */

  size_t lo = cache->size - (cache->size >> 2); /* ~ 3/4ths. */

  isc_mem_setwater(cache->tmctx, hi, lo);

}

void

dns_cache_setcachesize(dns_cache_t *cache, size_t size) {

  REQUIRE(VALID_CACHE(cache));

  /*

   * Impose a minimum cache size; pathological things happen if there

   * is too little room.

   */

  if (size < DNS_CACHE_MINSIZE) {

    size = DNS_CACHE_MINSIZE;

  }

  LOCK(&cache->lock);

  cache->size = size;

  updatewater(cache);

  UNLOCK(&cache->lock);

}

size_t

dns_cache_getcachesize(dns_cache_t *cache) {

  size_t size;

  REQUIRE(VALID_CACHE(cache));

  LOCK(&cache->lock);

  size = cache->size;

  UNLOCK(&cache->lock);

  return size;

}

void

dns_cache_setservestalettl(dns_cache_t *cache, dns_ttl_t ttl) {

  REQUIRE(VALID_CACHE(cache));

  LOCK(&cache->lock);

  cache->serve_stale_ttl = ttl;

  UNLOCK(&cache->lock);

  (void)dns_db_setservestalettl(cache->db, ttl);

}

dns_ttl_t

dns_cache_getservestalettl(dns_cache_t *cache) {

  dns_ttl_t ttl;

  isc_result_t result;

  REQUIRE(VALID_CACHE(cache));

  /*

   * Could get it straight from the dns_cache_t, but use db

   * to confirm the value that the db is really using.

   */

  result = dns_db_getservestalettl(cache->db, &ttl);

  return result == ISC_R_SUCCESS ? ttl : 0;

}

void

dns_cache_setservestalerefresh(dns_cache_t *cache, dns_ttl_t interval) {

  REQUIRE(VALID_CACHE(cache));

  LOCK(&cache->lock);

  cache->serve_stale_refresh = interval;

  UNLOCK(&cache->lock);

  (void)dns_db_setservestalerefresh(cache->db, interval);

}

dns_ttl_t

dns_cache_getservestalerefresh(dns_cache_t *cache) {

  isc_result_t result;

  dns_ttl_t interval;

  REQUIRE(VALID_CACHE(cache));

  result = dns_db_getservestalerefresh(cache->db, &interval);

  return result == ISC_R_SUCCESS ? interval : 0;

}

isc_result_t

dns_cache_flush(dns_cache_t *cache) {

  dns_db_t *db = NULL, *olddb = NULL;

  isc_mem_t *tmctx = NULL, *oldtmctx = NULL;

  RETERR(cache_create_db(cache, &db, &tmctx));

  LOCK(&cache->lock);

  isc_mem_clearwater(cache->tmctx);

  oldtmctx = cache->tmctx;

  cache->tmctx = tmctx;

  updatewater(cache);

  olddb = cache->db;

  cache->db = db;

  UNLOCK(&cache->lock);

  dns_db_detach(&olddb);

  isc_mem_detach(&oldtmctx);

  return ISC_R_SUCCESS;

}

static isc_result_t

clearnode(dns_db_t *db, dns_dbnode_t *node) {

  dns_rdatasetiter_t *iter = NULL;

  RETERR(dns_db_allrdatasets(db, node, NULL, DNS_DB_STALEOK,

           (isc_stdtime_t)0, &iter));

  DNS_RDATASETITER_FOREACH(iter) {

    isc_result_t result;

    dns_rdataset_t rdataset = DNS_RDATASET_INIT;

    dns_rdatasetiter_current(iter, &rdataset);

    result = dns_db_deleterdataset(db, node, NULL, rdataset.type,

                 rdataset.covers);

    dns_rdataset_disassociate(&rdataset);

    if (result != ISC_R_SUCCESS && result != DNS_R_UNCHANGED) {

      break;

    }

  }

  dns_rdatasetiter_destroy(&iter);

  return ISC_R_SUCCESS;

}

static isc_result_t

cleartree(dns_db_t *db, const dns_name_t *name) {

  isc_result_t result, answer = ISC_R_SUCCESS;

  dns_dbiterator_t *iter = NULL;

  dns_dbnode_t *node = NULL, *top = NULL;

  dns_fixedname_t fnodename;

  dns_name_t *nodename;

  /*

   * Create the node if it doesn't exist so dns_dbiterator_seek()

   * can find it.  We will continue even if this fails.

   */

  (void)dns_db_findnode(db, name, true, &top);

  nodename = dns_fixedname_initname(&fnodename);

  CHECK(dns_db_createiterator(db, 0, &iter));

  result = dns_dbiterator_seek(iter, name);

  if (result == DNS_R_PARTIALMATCH) {

    result = dns_dbiterator_next(iter);

  }

  if (result != ISC_R_SUCCESS) {

    goto cleanup;

  }

  while (result == ISC_R_SUCCESS) {

    result = dns_dbiterator_current(iter, &node, nodename);

    if (result == DNS_R_NEWORIGIN) {

      result = ISC_R_SUCCESS;

    }

    if (result != ISC_R_SUCCESS) {

      goto cleanup;

    }

    /*

     * Are we done?

     */

    if (!dns_name_issubdomain(nodename, name)) {

      goto cleanup;

    }

    /*

     * If clearnode fails record and move onto the next node.

     */

    result = clearnode(db, node);

    if (result != ISC_R_SUCCESS && answer == ISC_R_SUCCESS) {

      answer = result;

    }

    dns_db_detachnode(&node);

    result = dns_dbiterator_next(iter);

  }

cleanup:

  if (result == ISC_R_NOMORE || result == ISC_R_NOTFOUND) {

    result = ISC_R_SUCCESS;

  }

  if (result != ISC_R_SUCCESS && answer == ISC_R_SUCCESS) {

    answer = result;

  }

  if (node != NULL) {

    dns_db_detachnode(&node);

  }

  if (iter != NULL) {

    dns_dbiterator_destroy(&iter);

  }

  if (top != NULL) {

    dns_db_detachnode(&top);

  }

  return answer;

}

isc_result_t

dns_cache_flushname(dns_cache_t *cache, const dns_name_t *name) {

  return dns_cache_flushnode(cache, name, false);

}

isc_result_t

dns_cache_flushnode(dns_cache_t *cache, const dns_name_t *name, bool tree) {

  isc_result_t result;

  dns_dbnode_t *node = NULL;

  dns_db_t *db = NULL;

  if (tree && dns_name_equal(name, dns_rootname)) {

    return dns_cache_flush(cache);

  }

  LOCK(&cache->lock);

  if (cache->db != NULL) {

    dns_db_attach(cache->db, &db);

  }

  UNLOCK(&cache->lock);

  if (db == NULL) {

    return ISC_R_SUCCESS;

  }

  if (tree) {

    result = cleartree(cache->db, name);

  } else {

    result = dns_db_findnode(cache->db, name, false, &node);

    if (result == ISC_R_NOTFOUND) {

      result = ISC_R_SUCCESS;

      goto cleanup_db;

    }

    if (result != ISC_R_SUCCESS) {

      goto cleanup_db;

    }

    result = clearnode(cache->db, node);

    dns_db_detachnode(&node);

  }

cleanup_db:

  dns_db_detach(&db);

  return result;

}

isc_stats_t *

dns_cache_getstats(dns_cache_t *cache) {

  REQUIRE(VALID_CACHE(cache));

  return cache->stats;

}

void

dns_cache_updatestats(dns_cache_t *cache, isc_result_t result) {

  REQUIRE(VALID_CACHE(cache));

  if (cache->stats == NULL) {

    return;

  }

  switch (result) {

  case ISC_R_SUCCESS:

  case DNS_R_NCACHENXDOMAIN:

  case DNS_R_NCACHENXRRSET:

  case DNS_R_CNAME:

  case DNS_R_DNAME:

  case DNS_R_GLUE:

  case DNS_R_ZONECUT:

  case DNS_R_COVERINGNSEC:

    isc_stats_increment(cache->stats,

            dns_cachestatscounter_queryhits);

    break;

  default:

    isc_stats_increment(cache->stats,

            dns_cachestatscounter_querymisses);

  }

}

void

dns_cache_setmaxrrperset(dns_cache_t *cache, uint32_t value) {

  REQUIRE(VALID_CACHE(cache));

  cache->maxrrperset = value;

  if (cache->db != NULL) {

    dns_db_setmaxrrperset(cache->db, value);

  }

}

void

dns_cache_setmaxtypepername(dns_cache_t *cache, uint32_t value) {

  REQUIRE(VALID_CACHE(cache));

  cache->maxtypepername = value;

  if (cache->db != NULL) {

    dns_db_setmaxtypepername(cache->db, value);

  }

}

/*

 * XXX: Much of the following code has been copied in from statschannel.c.

 * We should refactor this into a generic function in stats.c that can be

 * called from both places.

 */

typedef struct cache_dumparg {

  isc_statsformat_t type;

  void *arg;     /* type dependent argument */

  int ncounters;     /* for general statistics */

  int *counterindices;   /* for general statistics */

  uint64_t *countervalues; /* for general statistics */

  isc_result_t result;

} cache_dumparg_t;

static void

getcounter(isc_statscounter_t counter, uint64_t val, void *arg) {

  cache_dumparg_t *dumparg = arg;

  REQUIRE(counter < dumparg->ncounters);

  dumparg->countervalues[counter] = val;

}

static void

getcounters(isc_stats_t *stats, isc_statsformat_t type, int ncounters,

      int *indices, uint64_t *values) {

  cache_dumparg_t dumparg;

  memset(values, 0, sizeof(values[0]) * ncounters);

  dumparg.type = type;

  dumparg.ncounters = ncounters;

  dumparg.counterindices = indices;

  dumparg.countervalues = values;

  isc_stats_dump(stats, getcounter, &dumparg, ISC_STATSDUMP_VERBOSE);

}

void

dns_cache_dumpstats(dns_cache_t *cache, FILE *fp) {

  int indices[dns_cachestatscounter_max];

  uint64_t values[dns_cachestatscounter_max];

  REQUIRE(VALID_CACHE(cache));

  getcounters(cache->stats, isc_statsformat_file,

        dns_cachestatscounter_max, indices, values);

  fprintf(fp, "%20" PRIu64 " %s\n", values[dns_cachestatscounter_hits],

    "cache hits");

  fprintf(fp, "%20" PRIu64 " %s\n", values[dns_cachestatscounter_misses],

    "cache misses");

  fprintf(fp, "%20" PRIu64 " %s\n",

    values[dns_cachestatscounter_queryhits],

    "cache hits (from query)");

  fprintf(fp, "%20" PRIu64 " %s\n",

    values[dns_cachestatscounter_querymisses],

    "cache misses (from query)");

  fprintf(fp, "%20" PRIu64 " %s\n",

    values[dns_cachestatscounter_deletelru],

    "cache records deleted due to memory exhaustion");

  fprintf(fp, "%20" PRIu64 " %s\n",

    values[dns_cachestatscounter_coveringnsec],

    "covering nsec returned");

  fprintf(fp, "%20u %s\n", dns_db_nodecount(cache->db),

    "cache database nodes");

  fprintf(fp, "%20" PRIu64 " %s\n", (uint64_t)isc_mem_inuse(cache->tmctx),

    "cache tree memory in use");

}

#ifdef HAVE_LIBXML2

#define TRY0(a)                     \

  do {                        \

    xmlrc = (a);        \

    if (xmlrc < 0)      \

      goto error; \

  } while (0)

static int

renderstat(const char *name, uint64_t value, xmlTextWriterPtr writer) {

  int xmlrc;

  TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "counter"));

  TRY0(xmlTextWriterWriteAttribute(writer, ISC_XMLCHAR "name",

           ISC_XMLCHAR name));

  TRY0(xmlTextWriterWriteFormatString(writer, "%" PRIu64 "", value));

  TRY0(xmlTextWriterEndElement(writer)); /* counter */

error:

  return xmlrc;

}

int

dns_cache_renderxml(dns_cache_t *cache, void *writer0) {

  int indices[dns_cachestatscounter_max];

  uint64_t values[dns_cachestatscounter_max];

  int xmlrc;

  xmlTextWriterPtr writer = (xmlTextWriterPtr)writer0;

  REQUIRE(VALID_CACHE(cache));

  getcounters(cache->stats, isc_statsformat_file,

        dns_cachestatscounter_max, indices, values);

  TRY0(renderstat("CacheHits", values[dns_cachestatscounter_hits],

      writer));

  TRY0(renderstat("CacheMisses", values[dns_cachestatscounter_misses],

      writer));

  TRY0(renderstat("QueryHits", values[dns_cachestatscounter_queryhits],

      writer));

  TRY0(renderstat("QueryMisses",

      values[dns_cachestatscounter_querymisses], writer));

  TRY0(renderstat("DeleteLRU", values[dns_cachestatscounter_deletelru],

      writer));

  TRY0(renderstat("CoveringNSEC",

      values[dns_cachestatscounter_coveringnsec], writer));

  TRY0(renderstat("CacheNodes", dns_db_nodecount(cache->db), writer));

  TRY0(renderstat("TreeMemInUse", isc_mem_inuse(cache->tmctx), writer));

error:

  return xmlrc;

}

#endif /* ifdef HAVE_LIBXML2 */

#ifdef HAVE_JSON_C

#define CHECKMEM(m)                              \

  do {                                     \

    if (m == NULL) {                 \

      result = ISC_R_NOMEMORY; \

      goto error;              \

    }                                \

  } while (0)

isc_result_t

dns_cache_renderjson(dns_cache_t *cache, void *cstats0) {

  isc_result_t result = ISC_R_SUCCESS;

  int indices[dns_cachestatscounter_max];

  uint64_t values[dns_cachestatscounter_max];

  json_object *obj;

  json_object *cstats = (json_object *)cstats0;

  REQUIRE(VALID_CACHE(cache));

  getcounters(cache->stats, isc_statsformat_file,

        dns_cachestatscounter_max, indices, values);

  obj = json_object_new_int64(values[dns_cachestatscounter_hits]);

  CHECKMEM(obj);

  json_object_object_add(cstats, "CacheHits", obj);

  obj = json_object_new_int64(values[dns_cachestatscounter_misses]);

  CHECKMEM(obj);

  json_object_object_add(cstats, "CacheMisses", obj);

  obj = json_object_new_int64(values[dns_cachestatscounter_queryhits]);

  CHECKMEM(obj);

  json_object_object_add(cstats, "QueryHits", obj);

  obj = json_object_new_int64(values[dns_cachestatscounter_querymisses]);

  CHECKMEM(obj);

  json_object_object_add(cstats, "QueryMisses", obj);

  obj = json_object_new_int64(values[dns_cachestatscounter_deletelru]);

  CHECKMEM(obj);

  json_object_object_add(cstats, "DeleteLRU", obj);

  obj = json_object_new_int64(values[dns_cachestatscounter_coveringnsec]);

  CHECKMEM(obj);

  json_object_object_add(cstats, "CoveringNSEC", obj);

  obj = json_object_new_int64(dns_db_nodecount(cache->db));

  CHECKMEM(obj);

  json_object_object_add(cstats, "CacheNodes", obj);

  obj = json_object_new_int64(isc_mem_inuse(cache->tmctx));

  CHECKMEM(obj);

  json_object_object_add(cstats, "TreeMemInUse", obj);

  result = ISC_R_SUCCESS;

error:

  return result;

}

#endif /* ifdef HAVE_JSON_C */