/*

 * 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/atomic.h>

#include <isc/file.h>

#include <isc/log.h>

#include <isc/magic.h>

#include <isc/mem.h>

#include <isc/result.h>

#include <isc/string.h>

#include <isc/tid.h>

#include <isc/util.h>

#include <dns/name.h>

#include <dns/qp.h>

#include <dns/rdataclass.h>

#include <dns/view.h>

#include <dns/zone.h>

#include <dns/zt.h>

#define ZTMAGIC      ISC_MAGIC('Z', 'T', 'b', 'l')

#define VALID_ZT(zt) ISC_MAGIC_VALID(zt, ZTMAGIC)

struct dns_zt {

  unsigned int magic;

  isc_mem_t *mctx;

  dns_qpmulti_t *multi;

  atomic_bool flush;

  isc_refcount_t references;

  isc_refcount_t loads_pending;

};

struct zt_load_params {

  dns_zt_t *zt;

  dns_zt_callback_t *loaddone;

  void *loaddone_arg;

  bool newonly;

};

struct zt_freeze_params {

  dns_view_t *view;

  bool freeze;

};

static void

ztqpattach(void *uctx ISC_ATTR_UNUSED, void *pval,

     uint32_t ival ISC_ATTR_UNUSED) {

  dns_zone_t *zone = pval;

  dns_zone_ref(zone);

}

static void

ztqpdetach(void *uctx ISC_ATTR_UNUSED, void *pval,

     uint32_t ival ISC_ATTR_UNUSED) {

  dns_zone_t *zone = pval;

  dns_zone_detach(&zone);

}

static size_t

ztqpmakekey(dns_qpkey_t key, void *uctx ISC_ATTR_UNUSED, void *pval,

      uint32_t ival ISC_ATTR_UNUSED) {

  dns_zone_t *zone = pval;

  dns_name_t *name = dns_zone_getorigin(zone);

  return dns_qpkey_fromname(key, name, DNS_DBNAMESPACE_NORMAL);

}

static void

ztqptriename(void *uctx, char *buf, size_t size) {

  dns_view_t *view = uctx;

  snprintf(buf, size, "view %s zone table", view->name);

}

static dns_qpmethods_t ztqpmethods = {

  ztqpattach,

  ztqpdetach,

  ztqpmakekey,

  ztqptriename,

};

void

dns_zt_create(isc_mem_t *mctx, dns_view_t *view, dns_zt_t **ztp) {

  dns_qpmulti_t *multi = NULL;

  dns_zt_t *zt = NULL;

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

  REQUIRE(view != NULL);

  dns_qpmulti_create(mctx, &ztqpmethods, view, &multi);

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

  *zt = (dns_zt_t){

    .magic = ZTMAGIC,

    .multi = multi,

    .references = 1,

  };

  isc_mem_attach(mctx, &zt->mctx);

  *ztp = zt;

}

/*

 * XXXFANF it isn't clear whether this function will be useful. There

 * is only one zone table per view, so it is probably enough to let

 * the qp-trie auto-GC do its thing. However it might be problematic

 * if a very large zone is replaced, and its database memory is

 * retained for a long time.

 */

void

dns_zt_compact(dns_zt_t *zt) {

  dns_qp_t *qp = NULL;

  REQUIRE(VALID_ZT(zt));

  dns_qpmulti_write(zt->multi, &qp);

  dns_qp_compact(qp, DNS_QPGC_ALL);

  dns_qpmulti_commit(zt->multi, &qp);

}

isc_result_t

dns_zt_mount(dns_zt_t *zt, dns_zone_t *zone) {

  isc_result_t result;

  dns_qp_t *qp = NULL;

  REQUIRE(VALID_ZT(zt));

  dns_qpmulti_write(zt->multi, &qp);

  result = dns_qp_insert(qp, zone, 0);

  dns_qp_compact(qp, DNS_QPGC_MAYBE);

  dns_qpmulti_commit(zt->multi, &qp);

  return result;

}

isc_result_t

dns_zt_unmount(dns_zt_t *zt, dns_zone_t *zone) {

  isc_result_t result;

  dns_qp_t *qp = NULL;

  REQUIRE(VALID_ZT(zt));

  dns_qpmulti_write(zt->multi, &qp);

  result = dns_qp_deletename(qp, dns_zone_getorigin(zone),

           DNS_DBNAMESPACE_NORMAL, NULL, NULL);

  dns_qp_compact(qp, DNS_QPGC_MAYBE);

  dns_qpmulti_commit(zt->multi, &qp);

  return result;

}

isc_result_t

dns_zt_find(dns_zt_t *zt, const dns_name_t *name, dns_ztfind_t options,

      dns_zone_t **zonep) {

  isc_result_t result;

  dns_qpread_t qpr;

  void *pval = NULL;

  dns_ztfind_t exactmask = DNS_ZTFIND_NOEXACT | DNS_ZTFIND_EXACT;

  dns_ztfind_t exactopts = options & exactmask;

  dns_qpchain_t chain;

  REQUIRE(VALID_ZT(zt));

  REQUIRE(exactopts != exactmask);

  dns_qpmulti_query(zt->multi, &qpr);

  if (exactopts == DNS_ZTFIND_EXACT) {

    result = dns_qp_getname(&qpr, name, DNS_DBNAMESPACE_NORMAL,

          &pval, NULL);

  } else {

    result = dns_qp_lookup(&qpr, name, DNS_DBNAMESPACE_NORMAL, NULL,

               NULL, &chain, &pval, NULL);

    if (exactopts == DNS_ZTFIND_NOEXACT && result == ISC_R_SUCCESS)

    {

      /* get pval from the previous chain link */

      int len = dns_qpchain_length(&chain);

      if (len >= 2) {

        dns_qpchain_node(&chain, len - 2, NULL, &pval,

             NULL);

        result = DNS_R_PARTIALMATCH;

      } else {

        result = ISC_R_NOTFOUND;

      }

    }

  }

  dns_qpread_destroy(zt->multi, &qpr);

  if (result == ISC_R_SUCCESS || result == DNS_R_PARTIALMATCH) {

    dns_zone_t *zone = pval;

    /*

     * If DNS_ZTFIND_MIRROR is set and the zone which was

     * determined to be the deepest match for the supplied name is

     * a mirror zone which is expired or not yet loaded, treat it

     * as non-existent.  This will trigger a fallback to recursion

     * instead of returning a SERVFAIL.

     *

     * Note that currently only the deepest match in the zone table

     * is checked.  Consider a server configured with two mirror

     * zones: "bar" and its child, "foo.bar".  If zone data is

     * available for "bar" but not for "foo.bar", a query with

     * QNAME equal to or below "foo.bar" will cause ISC_R_NOTFOUND

     * to be returned, not DNS_R_PARTIALMATCH, despite zone data

     * being available for "bar".  This is considered to be an edge

     * case, handling which more appropriately is possible, but

     * arguably not worth the added complexity.

     */

    if ((options & DNS_ZTFIND_MIRROR) != 0 &&

        dns_zone_gettype(zone) == dns_zone_mirror &&

        !dns_zone_isloaded(zone))

    {

      result = ISC_R_NOTFOUND;

    } else {

      dns_zone_attach(zone, zonep);

    }

  }

  return result;

}

void

dns_zt_attach(dns_zt_t *zt, dns_zt_t **ztp) {

  REQUIRE(VALID_ZT(zt));

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

  isc_refcount_increment(&zt->references);

  *ztp = zt;

}

static isc_result_t

flush(dns_zone_t *zone, void *uap) {

  UNUSED(uap);

  return dns_zone_flush(zone);

}

static void

zt_destroy(dns_zt_t *zt) {

  isc_refcount_destroy(&zt->references);

  isc_refcount_destroy(&zt->loads_pending);

  if (atomic_load_acquire(&zt->flush)) {

    (void)dns_zt_apply(zt, false, NULL, flush, NULL);

  }

  dns_qpmulti_destroy(&zt->multi);

  zt->magic = 0;

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

}

void

dns_zt_detach(dns_zt_t **ztp) {

  dns_zt_t *zt;

  REQUIRE(ztp != NULL && VALID_ZT(*ztp));

  zt = *ztp;

  *ztp = NULL;

  if (isc_refcount_decrement(&zt->references) == 1) {

    zt_destroy(zt);

  }

}

void

dns_zt_flush(dns_zt_t *zt) {

  REQUIRE(VALID_ZT(zt));

  atomic_store_release(&zt->flush, true);

}

static isc_result_t

load(dns_zone_t *zone, void *uap) {

  isc_result_t result;

  result = dns_zone_load(zone, uap != NULL);

  if (result == DNS_R_CONTINUE || result == ISC_R_LOADING ||

      result == DNS_R_UPTODATE || result == DNS_R_DYNAMIC)

  {

    result = ISC_R_SUCCESS;

  }

  return result;

}

isc_result_t

dns_zt_load(dns_zt_t *zt, bool stop, bool newonly) {

  REQUIRE(VALID_ZT(zt));

  return dns_zt_apply(zt, stop, NULL, load, newonly ? &newonly : NULL);

}

static void

loaded_all(struct zt_load_params *params) {

  if (params->loaddone != NULL) {

    params->loaddone(params->loaddone_arg);

  }

  isc_mem_put(params->zt->mctx, params, sizeof(*params));

}

/*

 * Decrement the loads_pending counter; when counter reaches

 * zero, call the loaddone callback that was initially set by

 * dns_zt_asyncload().

 */

static isc_result_t

loaded_one(void *uap) {

  struct zt_load_params *params = uap;

  dns_zt_t *zt = params->zt;

  REQUIRE(VALID_ZT(zt));

  if (isc_refcount_decrement(&zt->loads_pending) == 1) {

    loaded_all(params);

  }

  if (isc_refcount_decrement(&zt->references) == 1) {

    zt_destroy(zt);

  }

  return ISC_R_SUCCESS;

}

/*

 * Initiates asynchronous loading of zone 'zone'.  'callback' is a

 * pointer to a function which will be used to inform the caller when

 * the zone loading is complete.

 */

static isc_result_t

asyncload(dns_zone_t *zone, void *uap) {

  struct zt_load_params *params = uap;

  struct dns_zt *zt = params->zt;

  isc_result_t result;

  REQUIRE(VALID_ZT(zt));

  REQUIRE(zone != NULL);

  isc_refcount_increment(&zt->references);

  isc_refcount_increment(&zt->loads_pending);

  result = dns_zone_asyncload(zone, params->newonly, loaded_one, params);

  if (result != ISC_R_SUCCESS) {

    /*

     * Caller is holding a reference to zt->loads_pending

     * and zt->references so these can't decrement to zero.

     */

    isc_refcount_decrement1(&zt->references);

    isc_refcount_decrement1(&zt->loads_pending);

  }

  return ISC_R_SUCCESS;

}

isc_result_t

dns_zt_asyncload(dns_zt_t *zt, bool newonly, dns_zt_callback_t *loaddone,

     void *arg) {

  isc_result_t result;

  uint_fast32_t loads_pending;

  struct zt_load_params *params = NULL;

  REQUIRE(VALID_ZT(zt));

  /*

   * Obtain a reference to zt->loads_pending so that asyncload can

   * safely decrement both zt->references and zt->loads_pending

   * without going to zero.

   */

  loads_pending = isc_refcount_increment0(&zt->loads_pending);

  INSIST(loads_pending == 0);

  params = isc_mem_get(zt->mctx, sizeof(*params));

  *params = (struct zt_load_params){

    .zt = zt,

    .newonly = newonly,

    .loaddone = loaddone,

    .loaddone_arg = arg,

  };

  result = dns_zt_apply(zt, false, NULL, asyncload, params);

  /*

   * Have all the loads completed?

   */

  if (isc_refcount_decrement(&zt->loads_pending) == 1) {

    loaded_all(params);

  }

  return result;

}

static isc_result_t

freezezones(dns_zone_t *zone, void *uap) {

  struct zt_freeze_params *params = uap;

  bool frozen;

  isc_result_t result = ISC_R_SUCCESS;

  char classstr[DNS_RDATACLASS_FORMATSIZE];

  char zonename[DNS_NAME_FORMATSIZE];

  dns_zone_t *raw = NULL;

  dns_view_t *view;

  const char *vname;

  const char *sep;

  int level;

  dns_zone_getraw(zone, &raw);

  if (raw != NULL) {

    zone = raw;

  }

  if (params->view != dns_zone_getview(zone)) {

    if (raw != NULL) {

      dns_zone_detach(&raw);

    }

    return ISC_R_SUCCESS;

  }

  if (dns_zone_gettype(zone) != dns_zone_primary) {

    if (raw != NULL) {

      dns_zone_detach(&raw);

    }

    return ISC_R_SUCCESS;

  }

  if (!dns_zone_isdynamic(zone, true)) {

    if (raw != NULL) {

      dns_zone_detach(&raw);

    }

    return ISC_R_SUCCESS;

  }

  frozen = dns_zone_getupdatedisabled(zone);

  if (params->freeze) {

    if (frozen) {

      result = DNS_R_FROZEN;

    }

    if (result == ISC_R_SUCCESS) {

      result = dns_zone_flush(zone);

    }

    if (result == ISC_R_SUCCESS) {

      dns_zone_setupdatedisabled(zone, params->freeze);

    }

  } else {

    if (frozen) {

      result = dns_zone_loadandthaw(zone);

      if (result == DNS_R_CONTINUE ||

          result == ISC_R_LOADING || result == DNS_R_UPTODATE)

      {

        result = ISC_R_SUCCESS;

      }

    }

  }

  view = dns_zone_getview(zone);

  if (strcmp(view->name, "_bind") == 0 ||

      strcmp(view->name, "_default") == 0)

  {

    vname = "";

    sep = "";

  } else {

    vname = view->name;

    sep = " ";

  }

  dns_rdataclass_format(dns_zone_getclass(zone), classstr,

            sizeof(classstr));

  dns_name_format(dns_zone_getorigin(zone), zonename, sizeof(zonename));

  level = (result != ISC_R_SUCCESS) ? ISC_LOG_ERROR : ISC_LOG_DEBUG(1);

  isc_log_write(DNS_LOGCATEGORY_GENERAL, DNS_LOGMODULE_ZONE, level,

          "%s zone '%s/%s'%s%s: %s",

          params->freeze ? "freezing" : "thawing", zonename,

          classstr, sep, vname, isc_result_totext(result));

  if (raw != NULL) {

    dns_zone_detach(&raw);

  }

  return result;

}

isc_result_t

dns_zt_freezezones(dns_zt_t *zt, dns_view_t *view, bool freeze) {

  isc_result_t result, tresult;

  struct zt_freeze_params params = { view, freeze };

  REQUIRE(VALID_ZT(zt));

  result = dns_zt_apply(zt, false, &tresult, freezezones, &params);

  if (tresult == ISC_R_NOTFOUND) {

    tresult = ISC_R_SUCCESS;

  }

  return (result == ISC_R_SUCCESS) ? tresult : result;

}

typedef void

setview_cb(dns_zone_t *zone);

static isc_result_t

setview(dns_zone_t *zone, void *arg) {

  setview_cb *cb = arg;

  cb(zone);

  return ISC_R_SUCCESS;

}

void

dns_zt_setviewcommit(dns_zt_t *zt) {

  dns_zt_apply(zt, false, NULL, setview, dns_zone_setviewcommit);

}

void

dns_zt_setviewrevert(dns_zt_t *zt) {

  dns_zt_apply(zt, false, NULL, setview, dns_zone_setviewrevert);

}

isc_result_t

dns_zt_apply(dns_zt_t *zt, bool stop, isc_result_t *sub,

       isc_result_t (*action)(dns_zone_t *, void *), void *uap) {

  isc_result_t result = ISC_R_SUCCESS;

  isc_result_t tresult = ISC_R_SUCCESS;

  dns_qpiter_t qpi;

  dns_qpread_t qpr;

  void *zone = NULL;

  REQUIRE(VALID_ZT(zt));

  REQUIRE(action != NULL);

  dns_qpmulti_query(zt->multi, &qpr);

  dns_qpiter_init(&qpr, &qpi);

  while (dns_qpiter_next(&qpi, NULL, &zone, NULL) == ISC_R_SUCCESS) {

    result = action(zone, uap);

    if (tresult == ISC_R_SUCCESS) {

      tresult = result;

    }

    if (result != ISC_R_SUCCESS && stop) {

      break;

    }

  }

  dns_qpread_destroy(zt->multi, &qpr);

  SET_IF_NOT_NULL(sub, tresult);

  return result;

}