/src/bind9/lib/dns/update.c

Source
/*
 * 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.
 */

#include <inttypes.h>
#include <stdbool.h>
#include <time.h>

#include <isc/log.h>
#include <isc/magic.h>
#include <isc/mem.h>
#include <isc/netaddr.h>
#include <isc/random.h>
#include <isc/result.h>
#include <isc/serial.h>
#include <isc/stats.h>
#include <isc/stdtime.h>
#include <isc/string.h>
#include <isc/time.h>
#include <isc/util.h>

#include <dns/db.h>
#include <dns/dbiterator.h>
#include <dns/diff.h>
#include <dns/dnssec.h>
#include <dns/fixedname.h>
#include <dns/journal.h>
#include <dns/kasp.h>
#include <dns/keyvalues.h>
#include <dns/message.h>
#include <dns/nsec.h>
#include <dns/nsec3.h>
#include <dns/private.h>
#include <dns/rdataclass.h>
#include <dns/rdataset.h>
#include <dns/rdatasetiter.h>
#include <dns/rdatastruct.h>
#include <dns/rdatatype.h>
#include <dns/skr.h>
#include <dns/soa.h>
#include <dns/ssu.h>
#include <dns/stats.h>
#include <dns/tsig.h>
#include <dns/update.h>
#include <dns/view.h>
#include <dns/zone.h>
#include <dns/zoneproperties.h>
#include <dns/zt.h>

/**************************************************************************/

#define STATE_MAGIC        ISC_MAGIC('S', 'T', 'T', 'E')
#define DNS_STATE_VALID(state) ISC_MAGIC_VALID(state, STATE_MAGIC)

/*%
 * Log level for tracing dynamic update protocol requests.
 */
#define LOGLEVEL_PROTOCOL ISC_LOG_INFO

/*%
 * Log level for low-level debug tracing.
 */
#define LOGLEVEL_DEBUG ISC_LOG_DEBUG(8)

/**************************************************************************/

typedef struct rr rr_t;

struct rr {
  /* dns_name_t name; */
  uint32_t ttl;
  dns_rdata_t rdata;
};

typedef struct update_event update_event_t;

/**************************************************************************/

static void
update_log(dns_update_log_t *callback, dns_zone_t *zone, int level,
     const char *fmt, ...) ISC_FORMAT_PRINTF(4, 5);

static void
update_log(dns_update_log_t *callback, dns_zone_t *zone, int level,
     const char *fmt, ...) {
  va_list ap;
  char message[4096];

  if (callback == NULL) {
    return;
  }

  if (!isc_log_wouldlog(level)) {
    return;
  }

  va_start(ap, fmt);
  vsnprintf(message, sizeof(message), fmt, ap);
  va_end(ap);

  (callback->func)(callback->arg, zone, level, message);
}

/*%
 * Update a single RR in version 'ver' of 'db' and log the
 * update in 'diff'.
 *
 * Ensures:
 * \li  '*tuple' == NULL.  Either the tuple is freed, or its
 *  ownership has been transferred to the diff.
 */
static isc_result_t
do_one_tuple(dns_difftuple_t **tuple, dns_db_t *db, dns_dbversion_t *ver,
       dns_diff_t *diff) {
  dns_diff_t temp_diff;
  isc_result_t result;

  /*
   * Create a singleton diff.
   */
  dns_diff_init(diff->mctx, &temp_diff);
  ISC_LIST_APPEND(temp_diff.tuples, *tuple, link);

  /*
   * Apply it to the database.
   */
  result = dns_diff_apply(&temp_diff, db, ver);
  ISC_LIST_UNLINK(temp_diff.tuples, *tuple, link);
  if (result != ISC_R_SUCCESS) {
    dns_difftuple_free(tuple);
    return result;
  }

  /*
   * Merge it into the current pending journal entry.
   */
  dns_diff_appendminimal(diff, tuple);

  /*
   * Do not clear temp_diff.
   */
  return ISC_R_SUCCESS;
}

static isc_result_t
update_one_rr(dns_db_t *db, dns_dbversion_t *ver, dns_diff_t *diff,
        dns_diffop_t op, dns_name_t *name, dns_ttl_t ttl,
        dns_rdata_t *rdata) {
  dns_difftuple_t *tuple = NULL;
  dns_difftuple_create(diff->mctx, op, name, ttl, rdata, &tuple);
  return do_one_tuple(&tuple, db, ver, diff);
}

/**************************************************************************/
/*
 * Callback-style iteration over rdatasets and rdatas.
 *
 * foreach_rrset() can be used to iterate over the RRsets
 * of a name and call a callback function with each
 * one.  Similarly, foreach_rr() can be used to iterate
 * over the individual RRs at name, optionally restricted
 * to RRs of a given type.
 *
 * The callback functions are called "actions" and take
 * two arguments: a void pointer for passing arbitrary
 * context information, and a pointer to the current RRset
 * or RR.  By convention, their names end in "_action".
 */

/*
 * XXXRTH  We might want to make this public somewhere in libdns.
 */

/*%
 * Function type for foreach_rrset() iterator actions.
 */
typedef isc_result_t
rrset_func(void *data, dns_rdataset_t *rrset);

/*%
 * Function type for foreach_rr() iterator actions.
 */
typedef isc_result_t
rr_func(void *data, rr_t *rr);

/*%
 * Internal context struct for foreach_node_rr().
 */
typedef struct {
  rr_func *rr_action;
  void *rr_action_data;
} foreach_node_rr_ctx_t;

/*%
 * Internal helper function for foreach_node_rr().
 */
static isc_result_t
foreach_node_rr_action(void *data, dns_rdataset_t *rdataset) {
  foreach_node_rr_ctx_t *ctx = data;
  DNS_RDATASET_FOREACH(rdataset) {
    rr_t rr = { 0, DNS_RDATA_INIT };

    dns_rdataset_current(rdataset, &rr.rdata);
    rr.ttl = rdataset->ttl;
    RETERR((*ctx->rr_action)(ctx->rr_action_data, &rr));
  }

  return ISC_R_SUCCESS;
}

/*%
 * For each rdataset of 'name' in 'ver' of 'db', call 'action'
 * with the rdataset and 'action_data' as arguments.  If the name
 * does not exist, do nothing.
 *
 * If 'action' returns an error, abort iteration and return the error.
 */
static isc_result_t
foreach_rrset(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
        rrset_func *action, void *action_data) {
  isc_result_t result;
  dns_dbnode_t *node = NULL;
  dns_rdatasetiter_t *iter = NULL;

  result = dns_db_findnode(db, name, false, &node);
  if (result == ISC_R_NOTFOUND) {
    return ISC_R_SUCCESS;
  }
  if (result != ISC_R_SUCCESS) {
    return result;
  }

  result = dns_db_allrdatasets(db, node, ver, 0, (isc_stdtime_t)0, &iter);
  if (result != ISC_R_SUCCESS) {
    goto cleanup_node;
  }

  DNS_RDATASETITER_FOREACH(iter) {
    dns_rdataset_t rdataset = DNS_RDATASET_INIT;

    dns_rdatasetiter_current(iter, &rdataset);

    result = (*action)(action_data, &rdataset);

    dns_rdataset_disassociate(&rdataset);
    if (result != ISC_R_SUCCESS) {
      break;
    }
  }
  dns_rdatasetiter_destroy(&iter);

cleanup_node:
  dns_db_detachnode(&node);

  return result;
}

/*%
 * For each RR of 'name' in 'ver' of 'db', call 'action'
 * with the RR and 'action_data' as arguments.  If the name
 * does not exist, do nothing.
 *
 * If 'action' returns an error, abort iteration
 * and return the error.
 */
static isc_result_t
foreach_node_rr(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
    rr_func *rr_action, void *rr_action_data) {
  foreach_node_rr_ctx_t ctx;
  ctx.rr_action = rr_action;
  ctx.rr_action_data = rr_action_data;
  return foreach_rrset(db, ver, name, foreach_node_rr_action, &ctx);
}

/*%
 * For each of the RRs specified by 'db', 'ver', 'name', 'type',
 * (which can be dns_rdatatype_any to match any type), and 'covers', call
 * 'action' with the RR and 'action_data' as arguments. If the name
 * does not exist, or if no RRset of the given type exists at the name,
 * do nothing.
 *
 * If 'action' returns an error, abort iteration and return the error.
 */
static isc_result_t
foreach_rr(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
     dns_rdatatype_t type, dns_rdatatype_t covers, rr_func *rr_action,
     void *rr_action_data) {
  isc_result_t result;
  dns_dbnode_t *node;
  dns_rdataset_t rdataset;

  if (type == dns_rdatatype_any) {
    return foreach_node_rr(db, ver, name, rr_action,
               rr_action_data);
  }

  node = NULL;
  if (type == dns_rdatatype_nsec3 ||
      (type == dns_rdatatype_rrsig && covers == dns_rdatatype_nsec3))
  {
    result = dns_db_findnsec3node(db, name, false, &node);
  } else {
    result = dns_db_findnode(db, name, false, &node);
  }
  if (result == ISC_R_NOTFOUND) {
    return ISC_R_SUCCESS;
  }
  if (result != ISC_R_SUCCESS) {
    return result;
  }

  dns_rdataset_init(&rdataset);
  result = dns_db_findrdataset(db, node, ver, type, covers,
             (isc_stdtime_t)0, &rdataset, NULL);
  if (result == ISC_R_NOTFOUND) {
    result = ISC_R_SUCCESS;
    goto cleanup_node;
  }
  if (result != ISC_R_SUCCESS) {
    goto cleanup_node;
  }

  DNS_RDATASET_FOREACH(&rdataset) {
    rr_t rr = { 0, DNS_RDATA_INIT };
    dns_rdataset_current(&rdataset, &rr.rdata);
    rr.ttl = rdataset.ttl;
    result = (*rr_action)(rr_action_data, &rr);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_rdataset;
    }
  }

  result = ISC_R_SUCCESS;

cleanup_rdataset:
  dns_rdataset_disassociate(&rdataset);
cleanup_node:
  dns_db_detachnode(&node);

  return result;
}

/**************************************************************************/
/*
 * Various tests on the database contents (for prerequisites, etc).
 */

/*%
 * Function type for predicate functions that compare a database RR 'db_rr'
 * against an update RR 'update_rr'.
 */
typedef bool
rr_predicate(dns_rdata_t *update_rr, dns_rdata_t *db_rr);

/*%
 * Helper function for rrset_exists().
 */
static isc_result_t
rrset_exists_action(void *data, rr_t *rr) {
  UNUSED(data);
  UNUSED(rr);
  return ISC_R_EXISTS;
}

/*%
 * Utility macro for RR existence checking functions.
 *
 * If the variable 'result' has the value ISC_R_EXISTS or
 * ISC_R_SUCCESS, set *exists to true or false,
 * respectively, and return success.
 *
 * If 'result' has any other value, there was a failure.
 * Return the failure result code and do not set *exists.
 *
 * This would be more readable as "do { if ... } while(0)",
 * but that form generates tons of warnings on Solaris 2.6.
 */
#define RETURN_EXISTENCE_FLAG                                         \
  return ((result == ISC_R_EXISTS)                              \
      ? (*exists = true, ISC_R_SUCCESS)             \
      : ((result == ISC_R_SUCCESS)                  \
           ? (*exists = false, ISC_R_SUCCESS) \
           : result))

/*%
 * Set '*exists' to true iff an rrset of the given type exists,
 * to false otherwise.
 */
static isc_result_t
rrset_exists(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
       dns_rdatatype_t type, dns_rdatatype_t covers, bool *exists) {
  isc_result_t result;
  result = foreach_rr(db, ver, name, type, covers, rrset_exists_action,
          NULL);
  RETURN_EXISTENCE_FLAG;
}

/*%
 * Set '*visible' to true if the RRset exists and is part of the
 * visible zone.  Otherwise '*visible' is set to false unless a
 * error occurs.
 */
static isc_result_t
rrset_visible(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
        dns_rdatatype_t type, bool *visible) {
  isc_result_t result;
  dns_fixedname_t fixed;

  dns_fixedname_init(&fixed);
  result = dns_db_find(db, name, ver, type, DNS_DBFIND_NOWILD,
           (isc_stdtime_t)0, NULL, dns_fixedname_name(&fixed),
           NULL, NULL);
  switch (result) {
  case ISC_R_SUCCESS:
    *visible = true;
    break;
  /*
   * Glue, obscured, deleted or replaced records.
   */
  case DNS_R_DELEGATION:
  case DNS_R_DNAME:
  case DNS_R_CNAME:
  case DNS_R_NXDOMAIN:
  case DNS_R_NXRRSET:
  case DNS_R_EMPTYNAME:
  case DNS_R_COVERINGNSEC:
    *visible = false;
    result = ISC_R_SUCCESS;
    break;
  default:
    *visible = false; /* silence false compiler warning */
    break;
  }
  return result;
}

/*%
 * Context struct and helper function for name_exists().
 */

static isc_result_t
name_exists_action(void *data, dns_rdataset_t *rrset) {
  UNUSED(data);
  UNUSED(rrset);
  return ISC_R_EXISTS;
}

/*%
 * Set '*exists' to true iff the given name exists, to false otherwise.
 */
static isc_result_t
name_exists(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
      bool *exists) {
  isc_result_t result;
  result = foreach_rrset(db, ver, name, name_exists_action, NULL);
  RETURN_EXISTENCE_FLAG;
}

/**************************************************************************/
/*
 * Checking of "RRset exists (value dependent)" prerequisites.
 *
 * In the RFC2136 section 3.2.5, this is the pseudocode involving
 * a variable called "temp", a mapping of <name, type> tuples to rrsets.
 *
 * Here, we represent the "temp" data structure as (non-minimal) "dns_diff_t"
 * where each tuple has op==DNS_DIFFOP_EXISTS.
 */

/*%
 * A comparison function defining the sorting order for the entries
 * in the "temp" data structure.  The major sort key is the owner name,
 * followed by the type and rdata.
 */
static int
temp_order(const void *av, const void *bv) {
  dns_difftuple_t const *const *ap = av;
  dns_difftuple_t const *const *bp = bv;
  dns_difftuple_t const *a = *ap;
  dns_difftuple_t const *b = *bp;
  int r;
  r = dns_name_compare(&a->name, &b->name);
  if (r != 0) {
    return r;
  }
  r = (b->rdata.type - a->rdata.type);
  if (r != 0) {
    return r;
  }
  r = dns_rdata_casecompare(&a->rdata, &b->rdata);
  return r;
}

/**************************************************************************/
/*
 * Conditional deletion of RRs.
 */

/*%
 * Context structure for delete_if().
 */

typedef struct {
  rr_predicate *predicate;
  dns_db_t *db;
  dns_dbversion_t *ver;
  dns_diff_t *diff;
  dns_name_t *name;
  dns_rdata_t *update_rr;
} conditional_delete_ctx_t;

/*%
 * Predicate functions for delete_if().
 */

/*%
 * Return true always.
 */
static bool
true_p(dns_rdata_t *update_rr, dns_rdata_t *db_rr) {
  UNUSED(update_rr);
  UNUSED(db_rr);
  return true;
}

/*%
 * Return true if the record is a RRSIG.
 */
static bool
rrsig_p(dns_rdata_t *update_rr, dns_rdata_t *db_rr) {
  UNUSED(update_rr);
  return (db_rr->type == dns_rdatatype_rrsig) ? true : false;
}

/*%
 * Internal helper function for delete_if().
 */
static isc_result_t
delete_if_action(void *data, rr_t *rr) {
  conditional_delete_ctx_t *ctx = data;
  if ((*ctx->predicate)(ctx->update_rr, &rr->rdata)) {
    isc_result_t result;
    result = update_one_rr(ctx->db, ctx->ver, ctx->diff,
               DNS_DIFFOP_DEL, ctx->name, rr->ttl,
               &rr->rdata);
    return result;
  } else {
    return ISC_R_SUCCESS;
  }
}

/*%
 * Conditionally delete RRs.  Apply 'predicate' to the RRs
 * specified by 'db', 'ver', 'name', and 'type' (which can
 * be dns_rdatatype_any to match any type).  Delete those
 * RRs for which the predicate returns true, and log the
 * deletions in 'diff'.
 */
static isc_result_t
delete_if(rr_predicate *predicate, dns_db_t *db, dns_dbversion_t *ver,
    dns_name_t *name, dns_rdatatype_t type, dns_rdatatype_t covers,
    dns_rdata_t *update_rr, dns_diff_t *diff) {
  conditional_delete_ctx_t ctx;
  ctx.predicate = predicate;
  ctx.db = db;
  ctx.ver = ver;
  ctx.diff = diff;
  ctx.name = name;
  ctx.update_rr = update_rr;
  return foreach_rr(db, ver, name, type, covers, delete_if_action, &ctx);
}

/**************************************************************************/
/*
 * Incremental updating of NSECs and RRSIGs.
 */

/*%
 * We abuse the dns_diff_t type to represent a set of domain names
 * affected by the update.
 */
static void
namelist_append_name(dns_diff_t *list, dns_name_t *name) {
  dns_difftuple_t *tuple = NULL;
  static dns_rdata_t dummy_rdata = DNS_RDATA_INIT;

  dns_difftuple_create(list->mctx, DNS_DIFFOP_EXISTS, name, 0,
           &dummy_rdata, &tuple);
  dns_diff_append(list, &tuple);
}

static isc_result_t
namelist_append_subdomain(dns_db_t *db, dns_name_t *name,
        dns_diff_t *affected) {
  isc_result_t result;
  dns_fixedname_t fixedname;
  dns_name_t *child;
  dns_dbiterator_t *dbit = NULL;

  child = dns_fixedname_initname(&fixedname);

  CHECK(dns_db_createiterator(db, DNS_DB_NONSEC3, &dbit));

  for (result = dns_dbiterator_seek(dbit, name); result == ISC_R_SUCCESS;
       result = dns_dbiterator_next(dbit))
  {
    dns_dbnode_t *node = NULL;
    CHECK(dns_dbiterator_current(dbit, &node, child));
    dns_db_detachnode(&node);
    if (!dns_name_issubdomain(child, name)) {
      break;
    }
    namelist_append_name(affected, child);
  }
  if (result == ISC_R_NOMORE) {
    result = ISC_R_SUCCESS;
  }
cleanup:
  if (dbit != NULL) {
    dns_dbiterator_destroy(&dbit);
  }
  return result;
}

/*%
 * Helper function for non_nsec_rrset_exists().
 */
static isc_result_t
is_non_nsec_action(void *data, dns_rdataset_t *rrset) {
  UNUSED(data);
  if (!(dns_rdatatype_isnsec(rrset->type) ||
        (rrset->type == dns_rdatatype_rrsig &&
         dns_rdatatype_isnsec(rrset->covers))))
  {
    return ISC_R_EXISTS;
  }
  return ISC_R_SUCCESS;
}

/*%
 * Check whether there is an rrset other than a NSEC or RRSIG NSEC,
 * i.e., anything that justifies the continued existence of a name
 * after a secure update.
 *
 * If such an rrset exists, set '*exists' to true.
 * Otherwise, set it to false.
 */
static isc_result_t
non_nsec_rrset_exists(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
          bool *exists) {
  isc_result_t result;
  result = foreach_rrset(db, ver, name, is_non_nsec_action, NULL);
  RETURN_EXISTENCE_FLAG;
}

/*%
 * A comparison function for sorting dns_diff_t:s by name.
 */
static int
name_order(const void *av, const void *bv) {
  dns_difftuple_t const *const *ap = av;
  dns_difftuple_t const *const *bp = bv;
  dns_difftuple_t const *a = *ap;
  dns_difftuple_t const *b = *bp;
  return dns_name_compare(&a->name, &b->name);
}

static isc_result_t
uniqify_name_list(dns_diff_t *list) {
  isc_result_t result;

  CHECK(dns_diff_sort(list, name_order));

  dns_name_t *curr_name = NULL;
  ISC_LIST_FOREACH(list->tuples, p, link) {
    if (curr_name == NULL || !dns_name_equal(curr_name, &p->name)) {
      curr_name = &(p->name);
    } else {
      ISC_LIST_UNLINK(list->tuples, p, link);
      dns_difftuple_free(&p);
    }
  }
cleanup:
  return result;
}

static isc_result_t
is_active(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name, bool *flag,
    bool *cut, bool *unsecure) {
  isc_result_t result;
  dns_fixedname_t foundname;
  dns_fixedname_init(&foundname);
  result = dns_db_find(db, name, ver, dns_rdatatype_any,
           DNS_DBFIND_GLUEOK | DNS_DBFIND_NOWILD,
           (isc_stdtime_t)0, NULL,
           dns_fixedname_name(&foundname), NULL, NULL);
  if (result == ISC_R_SUCCESS || result == DNS_R_EMPTYNAME) {
    *flag = true;
    *cut = false;
    SET_IF_NOT_NULL(unsecure, false);
    return ISC_R_SUCCESS;
  } else if (result == DNS_R_ZONECUT) {
    *flag = true;
    *cut = true;
    if (unsecure != NULL) {
      /*
       * We are at the zonecut.  Check to see if there
       * is a DS RRset.
       */
      if (dns_db_find(db, name, ver, dns_rdatatype_ds, 0,
          (isc_stdtime_t)0, NULL,
          dns_fixedname_name(&foundname), NULL,
          NULL) == DNS_R_NXRRSET)
      {
        *unsecure = true;
      } else {
        *unsecure = false;
      }
    }
    return ISC_R_SUCCESS;
  } else if (result == DNS_R_GLUE || result == DNS_R_DNAME ||
       result == DNS_R_DELEGATION || result == DNS_R_NXDOMAIN)
  {
    *flag = false;
    *cut = false;
    SET_IF_NOT_NULL(unsecure, false);
    return ISC_R_SUCCESS;
  } else {
    /*
     * Silence compiler.
     */
    *flag = false;
    *cut = false;
    SET_IF_NOT_NULL(unsecure, false);
    return result;
  }
}

/*%
 * Find the next/previous name that has a NSEC record.
 * In other words, skip empty database nodes and names that
 * have had their NSECs removed because they are obscured by
 * a zone cut.
 */
static isc_result_t
next_active(dns_update_log_t *log, dns_zone_t *zone, dns_db_t *db,
      dns_dbversion_t *ver, dns_name_t *oldname, dns_name_t *newname,
      bool forward) {
  isc_result_t result;
  dns_dbiterator_t *dbit = NULL;
  bool has_nsec = false;
  unsigned int wraps = 0;
  bool secure = dns_db_issecure(db);

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

  CHECK(dns_dbiterator_seek(dbit, oldname));
  do {
    dns_dbnode_t *node = NULL;

    if (forward) {
      result = dns_dbiterator_next(dbit);
    } else {
      result = dns_dbiterator_prev(dbit);
    }
    if (result == ISC_R_NOMORE) {
      /*
       * Wrap around.
       */
      if (forward) {
        CHECK(dns_dbiterator_first(dbit));
      } else {
        CHECK(dns_dbiterator_last(dbit));
      }
      wraps++;
      if (wraps == 2) {
        update_log(log, zone, ISC_LOG_ERROR,
             "secure zone with no NSECs");
        CLEANUP(DNS_R_BADZONE);
      }
    }
    CHECK(dns_dbiterator_current(dbit, &node, newname));
    dns_db_detachnode(&node);

    /*
     * The iterator may hold the tree lock, and
     * rrset_exists() calls dns_db_findnode() which
     * may try to reacquire it.  To avoid deadlock
     * we must pause the iterator first.
     */
    CHECK(dns_dbiterator_pause(dbit));
    if (secure) {
      CHECK(rrset_exists(db, ver, newname, dns_rdatatype_nsec,
             0, &has_nsec));
    } else {
      dns_fixedname_t ffound;
      dns_name_t *found;
      found = dns_fixedname_initname(&ffound);
      result = dns_db_find(
        db, newname, ver, dns_rdatatype_soa,
        DNS_DBFIND_NOWILD, 0, NULL, found, NULL, NULL);
      if (result == ISC_R_SUCCESS ||
          result == DNS_R_EMPTYNAME ||
          result == DNS_R_NXRRSET || result == DNS_R_CNAME ||
          (result == DNS_R_DELEGATION &&
           dns_name_equal(newname, found)))
      {
        has_nsec = true;
        result = ISC_R_SUCCESS;
      } else if (result != DNS_R_NXDOMAIN) {
        break;
      }
    }
  } while (!has_nsec);
cleanup:
  if (dbit != NULL) {
    dns_dbiterator_destroy(&dbit);
  }

  return result;
}

/*%
 * Add a NSEC record for "name", recording the change in "diff".
 * The existing NSEC is removed.
 */
static isc_result_t
add_nsec(dns_update_log_t *log, dns_zone_t *zone, dns_db_t *db,
   dns_dbversion_t *ver, dns_name_t *name, dns_ttl_t nsecttl,
   dns_diff_t *diff) {
  isc_result_t result;
  dns_dbnode_t *node = NULL;
  unsigned char buffer[DNS_NSEC_BUFFERSIZE];
  dns_rdata_t rdata = DNS_RDATA_INIT;
  dns_difftuple_t *tuple = NULL;
  dns_fixedname_t fixedname;
  dns_name_t *target;

  target = dns_fixedname_initname(&fixedname);

  /*
   * Find the successor name, aka NSEC target.
   */
  CHECK(next_active(log, zone, db, ver, name, target, true));

  /*
   * Create the NSEC RDATA.
   */
  CHECK(dns_db_findnode(db, name, false, &node));
  dns_rdata_init(&rdata);
  CHECK(dns_nsec_buildrdata(db, ver, node, target, buffer, &rdata));
  dns_db_detachnode(&node);

  /*
   * Delete the old NSEC and record the change.
   */
  CHECK(delete_if(true_p, db, ver, name, dns_rdatatype_nsec, 0, NULL,
      diff));
  /*
   * Add the new NSEC and record the change.
   */
  dns_difftuple_create(diff->mctx, DNS_DIFFOP_ADD, name, nsecttl, &rdata,
           &tuple);
  CHECK(do_one_tuple(&tuple, db, ver, diff));
  INSIST(tuple == NULL);

cleanup:
  if (node != NULL) {
    dns_db_detachnode(&node);
  }
  return result;
}

/*%
 * Add a placeholder NSEC record for "name", recording the change in "diff".
 */
static isc_result_t
add_placeholder_nsec(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
         dns_diff_t *diff) {
  isc_result_t result;
  dns_difftuple_t *tuple = NULL;
  isc_region_t r;
  unsigned char data[1] = { 0 }; /* The root domain, no bits. */
  dns_rdata_t rdata = DNS_RDATA_INIT;

  r.base = data;
  r.length = sizeof(data);
  dns_rdata_fromregion(&rdata, dns_db_class(db), dns_rdatatype_nsec, &r);
  dns_difftuple_create(diff->mctx, DNS_DIFFOP_ADD, name, 0, &rdata,
           &tuple);
  CHECK(do_one_tuple(&tuple, db, ver, diff));
cleanup:
  return result;
}

static isc_result_t
find_zone_keys(dns_zone_t *zone, isc_mem_t *mctx, unsigned int maxkeys,
         dst_key_t **keys, unsigned int *nkeys) {
  dns_dnsseckeylist_t keylist;
  unsigned int count = 0;
  isc_result_t result;
  isc_stdtime_t now = isc_stdtime_now();
  dns_kasp_t *kasp;
  dns_keystorelist_t *keystores;
  const char *keydir;

  ISC_LIST_INIT(keylist);

  kasp = dns_zone_getkasp(zone);
  keydir = dns_zone_getkeydirectory(zone);
  keystores = dns_zone_getkeystores(zone);

  dns_zone_lock_keyfiles(zone);
  result = dns_dnssec_findmatchingkeys(dns_zone_getorigin(zone), kasp,
               keydir, keystores, now, false,
               mctx, &keylist);
  dns_zone_unlock_keyfiles(zone);

  if (result != ISC_R_SUCCESS) {
    *nkeys = 0;
    return result;
  }

  /* Add new 'dnskeys' to 'keys' */
  ISC_LIST_FOREACH(keylist, k, link) {
    if (count >= maxkeys) {
      ISC_LIST_UNLINK(keylist, k, link);
      dns_dnsseckey_destroy(mctx, &k);
      result = ISC_R_NOSPACE;
      break;
    }

    /* Detect inactive keys */
    if (!dns_dnssec_keyactive(k->key, now)) {
      dst_key_setinactive(k->key, true);
    }

    keys[count] = k->key;
    k->key = NULL;
    count++;

    ISC_LIST_UNLINK(keylist, k, link);
    dns_dnsseckey_destroy(mctx, &k);
  }

  *nkeys = count;
  return result;
}

/*%
 * Add RRSIG records for an RRset, recording the change in "diff".
 */
static isc_result_t
add_sigs(dns_update_log_t *log, dns_zone_t *zone, dns_db_t *db,
   dns_dbversion_t *ver, dns_name_t *name, dns_rdatatype_t type,
   dns_diff_t *diff, dst_key_t **keys, unsigned int nkeys,
   isc_stdtime_t now, isc_stdtime_t inception, isc_stdtime_t expire) {
  isc_result_t result;
  dns_dbnode_t *node = NULL;
  dns_kasp_t *kasp = dns_zone_getkasp(zone);
  dns_rdataset_t rdataset;
  dns_rdata_t sig_rdata = DNS_RDATA_INIT;
  dns_stats_t *dnssecsignstats = dns_zone_getdnssecsignstats(zone);
  isc_buffer_t buffer;
  unsigned char data[1024]; /* XXX */
  unsigned int i;
  bool added_sig = false;
  bool use_kasp = false;
  bool offlineksk = false;
  isc_mem_t *mctx = diff->mctx;

  if (kasp != NULL) {
    use_kasp = true;
    offlineksk = dns_kasp_offlineksk(kasp);
  }

  dns_rdataset_init(&rdataset);
  isc_buffer_init(&buffer, data, sizeof(data));

  /* Get the rdataset to sign. */
  if (type == dns_rdatatype_nsec3) {
    CHECK(dns_db_findnsec3node(db, name, false, &node));
  } else {
    CHECK(dns_db_findnode(db, name, false, &node));
  }
  CHECK(dns_db_findrdataset(db, node, ver, type, 0, (isc_stdtime_t)0,
          &rdataset, NULL));
  dns_db_detachnode(&node);

#define REVOKE(x) ((dst_key_flags(x) & DNS_KEYFLAG_REVOKE) != 0)
#define KSK(x)    ((dst_key_flags(x) & DNS_KEYFLAG_KSK) != 0)
#define ID(x)   dst_key_id(x)
#define ALG(x)    dst_key_alg(x)

  /*
   * If we are honoring KSK flags then we need to check that we
   * have both KSK and non-KSK keys that are not revoked per
   * algorithm.
   */
  for (i = 0; i < nkeys; i++) {
    bool both = false;

    /* Don't add signatures for offline or inactive keys */
    if (!dst_key_isprivate(keys[i]) && !offlineksk) {
      continue;
    }
    if (dst_key_inactive(keys[i]) && !offlineksk) {
      continue;
    }

    if (use_kasp) {
      /*
       * A dnssec-policy is found. Check what RRsets this
       * key should sign.
       */
      isc_stdtime_t when;
      isc_result_t kresult;
      bool ksk = false;
      bool zsk = false;

      kresult = dst_key_getbool(keys[i], DST_BOOL_KSK, &ksk);
      if (kresult != ISC_R_SUCCESS) {
        if (KSK(keys[i])) {
          ksk = true;
        }
      }
      kresult = dst_key_getbool(keys[i], DST_BOOL_ZSK, &zsk);
      if (kresult != ISC_R_SUCCESS) {
        if (!KSK(keys[i])) {
          zsk = true;
        }
      }

      if (!dst_key_isprivate(keys[i]) && offlineksk && zsk) {
        continue;
      }
      if (dst_key_inactive(keys[i]) && offlineksk && zsk) {
        continue;
      }

      if (dns_rdatatype_iskeymaterial(type)) {
        /*
         * DNSKEY RRset is signed with KSK.
         * CDS and CDNSKEY RRsets too (RFC 7344, 4.1).
         */
        if (!ksk) {
          continue;
        }
      } else if (!zsk) {
        /*
         * Other RRsets are signed with ZSK.
         */
        continue;
      } else if (zsk &&
           !dst_key_is_signing(keys[i], DST_BOOL_ZSK,
                   now, &when))
      {
        /*
         * This key is not active for zone-signing.
         */
        continue;
      }
    } else if (!REVOKE(keys[i])) {
      /*
       * Don't consider inactive keys, however the KSK may be
       * temporary offline, so do consider KSKs which private
       * key files are unavailable.
       */
      both = dst_key_have_ksk_and_zsk(
        keys, nkeys, i, false, KSK(keys[i]),
        !KSK(keys[i]), NULL, NULL);
      if (both) {
        /*
         * CDS and CDNSKEY are signed with KSK (RFC
         * 7344, 4.1).
         */
        if (dns_rdatatype_iskeymaterial(type)) {
          if (!KSK(keys[i])) {
            continue;
          }
        } else if (KSK(keys[i])) {
          continue;
        }
      }
    }

    /*
     * If this key is revoked, it may only sign the DNSKEY RRset.
     */
    if (REVOKE(keys[i]) && type != dns_rdatatype_dnskey) {
      continue;
    }

    /* Calculate the signature, creating a RRSIG RDATA. */
    if (offlineksk && dns_rdatatype_iskeymaterial(type)) {
      /* Look up the signature in the SKR bundle */
      dns_skrbundle_t *bundle = dns_zone_getskrbundle(zone);
      if (bundle == NULL) {
        CLEANUP(DNS_R_NOSKRBUNDLE);
      }
      CHECK(dns_skrbundle_getsig(bundle, keys[i], type,
               &sig_rdata));
    } else {
      CHECK(dns_dnssec_sign(name, &rdataset, keys[i],
                &inception, &expire, mctx,
                &buffer, &sig_rdata));
    }

    /* Update the database and journal with the RRSIG. */
    /* XXX inefficient - will cause dataset merging */
    CHECK(update_one_rr(db, ver, diff, DNS_DIFFOP_ADDRESIGN, name,
            rdataset.ttl, &sig_rdata));
    dns_rdata_reset(&sig_rdata);
    isc_buffer_init(&buffer, data, sizeof(data));
    added_sig = true;
    /* Update DNSSEC sign statistics. */
    if (dnssecsignstats != NULL) {
      dns_dnssecsignstats_increment(dnssecsignstats,
                  ID(keys[i]),
                  (uint8_t)ALG(keys[i]),
                  dns_dnssecsignstats_sign);
    }
  }
  if (!added_sig) {
    update_log(log, zone, ISC_LOG_ERROR,
         "found no active private keys, "
         "unable to generate any signatures");
    result = ISC_R_NOTFOUND;
  }

cleanup:
  dns_rdataset_cleanup(&rdataset);
  if (node != NULL) {
    dns_db_detachnode(&node);
  }
  return result;
}

/*
 * Delete expired RRsigs and any RRsigs we are about to re-sign.
 * See also zone.c:del_sigs().
 */
static isc_result_t
del_keysigs(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
      dns_diff_t *diff, dst_key_t **keys, unsigned int nkeys) {
  isc_result_t result;
  dns_dbnode_t *node = NULL;
  dns_rdataset_t rdataset;
  unsigned int i;
  dns_rdata_rrsig_t rrsig;
  bool found;

  dns_rdataset_init(&rdataset);

  result = dns_db_findnode(db, name, false, &node);
  if (result == ISC_R_NOTFOUND) {
    return ISC_R_SUCCESS;
  }
  CHECK(result);

  result = dns_db_findrdataset(db, node, ver, dns_rdatatype_rrsig,
             dns_rdatatype_dnskey, (isc_stdtime_t)0,
             &rdataset, NULL);
  dns_db_detachnode(&node);

  if (result == ISC_R_NOTFOUND) {
    return ISC_R_SUCCESS;
  }
  CHECK(result);

  DNS_RDATASET_FOREACH(&rdataset) {
    dns_rdata_t rdata = DNS_RDATA_INIT;
    dns_rdataset_current(&rdataset, &rdata);
    result = dns_rdata_tostruct(&rdata, &rrsig, NULL);
    RUNTIME_CHECK(result == ISC_R_SUCCESS);
    found = false;
    for (i = 0; i < nkeys; i++) {
      if (rrsig.keyid == dst_key_id(keys[i])) {
        found = true;
        if (!dst_key_isprivate(keys[i]) &&
            !dst_key_inactive(keys[i]))
        {
          /*
           * The re-signing code in zone.c
           * will mark this as offline.
           * Just skip the record for now.
           */
          break;
        }
        result = update_one_rr(db, ver, diff,
                   DNS_DIFFOP_DEL, name,
                   rdataset.ttl, &rdata);
        break;
      }
    }
    /*
     * If there is not a matching DNSKEY then delete the RRSIG.
     */
    if (!found) {
      result = update_one_rr(db, ver, diff, DNS_DIFFOP_DEL,
                 name, rdataset.ttl, &rdata);
    }
    dns_rdata_reset(&rdata);
    if (result != ISC_R_SUCCESS) {
      break;
    }
  }
  dns_rdataset_disassociate(&rdataset);

cleanup:
  if (node != NULL) {
    dns_db_detachnode(&node);
  }
  return result;
}

static isc_result_t
add_exposed_sigs(dns_update_log_t *log, dns_zone_t *zone, dns_db_t *db,
     dns_dbversion_t *ver, dns_name_t *name, bool cut,
     dns_diff_t *diff, dst_key_t **keys, unsigned int nkeys,
     isc_stdtime_t now, isc_stdtime_t inception,
     isc_stdtime_t expire, unsigned int *sigs) {
  isc_result_t result;
  dns_dbnode_t *node;
  dns_rdatasetiter_t *iter;

  node = NULL;
  result = dns_db_findnode(db, name, false, &node);
  if (result == ISC_R_NOTFOUND) {
    return ISC_R_SUCCESS;
  }
  if (result != ISC_R_SUCCESS) {
    return result;
  }

  iter = NULL;
  result = dns_db_allrdatasets(db, node, ver, 0, (isc_stdtime_t)0, &iter);
  if (result != ISC_R_SUCCESS) {
    goto cleanup_node;
  }

  DNS_RDATASETITER_FOREACH(iter) {
    dns_rdataset_t rdataset = DNS_RDATASET_INIT;
    dns_rdatatype_t type;
    bool flag;

    dns_rdatasetiter_current(iter, &rdataset);
    type = rdataset.type;
    dns_rdataset_disassociate(&rdataset);

    /*
     * We don't need to sign unsigned NSEC records at the cut
     * as they are handled elsewhere.
     */
    if ((type == dns_rdatatype_rrsig) ||
        (cut && type != dns_rdatatype_ds))
    {
      continue;
    }
    result = rrset_exists(db, ver, name, dns_rdatatype_rrsig, type,
              &flag);
    if (result != ISC_R_SUCCESS) {
      break;
    }
    if (flag) {
      continue;
    }
    result = add_sigs(log, zone, db, ver, name, type, diff, keys,
          nkeys, now, inception, expire);
    if (result != ISC_R_SUCCESS) {
      break;
    }
    (*sigs)++;
  }
  dns_rdatasetiter_destroy(&iter);

cleanup_node:
  dns_db_detachnode(&node);

  return result;
}

/*%
 * Update RRSIG, NSEC and NSEC3 records affected by an update.  The original
 * update, including the SOA serial update but excluding the RRSIG & NSEC
 * changes, is in "diff" and has already been applied to "newver" of "db".
 * The database version prior to the update is "oldver".
 *
 * The necessary RRSIG, NSEC and NSEC3 changes will be applied to "newver"
 * and added (as a minimal diff) to "diff".
 *
 * The RRSIGs generated will be valid for 'sigvalidityinterval' seconds.
 */
isc_result_t
dns_update_signatures(dns_update_log_t *log, dns_zone_t *zone, dns_db_t *db,
          dns_dbversion_t *oldver, dns_dbversion_t *newver,
          dns_diff_t *diff, uint32_t sigvalidityinterval) {
  return dns_update_signaturesinc(log, zone, db, oldver, newver, diff,
          sigvalidityinterval, NULL);
}

struct dns_update_state {
  unsigned int magic;
  dns_diff_t diffnames;
  dns_diff_t affected;
  dns_diff_t sig_diff;
  dns_diff_t nsec_diff;
  dns_diff_t nsec_mindiff;
  dns_diff_t work;
  dst_key_t *zone_keys[DNS_MAXZONEKEYS];
  unsigned int nkeys;
  isc_stdtime_t now, inception, expire, soaexpire, keyexpire;
  dns_ttl_t nsecttl;
  bool build_nsec3;
  enum {
    sign_updates,
    remove_orphaned,
    build_chain,
    process_nsec,
    sign_nsec,
    update_nsec3,
    process_nsec3,
    sign_nsec3
  } state;
};

static uint32_t
dns__jitter_expire(dns_zone_t *zone) {
  /* Spread out signatures over time */
  isc_stdtime_t jitter = DEFAULT_JITTER;
  isc_stdtime_t sigvalidity = dns_zone_getsigvalidityinterval(zone);
  dns_kasp_t *kasp = dns_zone_getkasp(zone);

  if (kasp != NULL) {
    jitter = dns_kasp_sigjitter(kasp);
    sigvalidity = dns_kasp_sigvalidity(kasp);
    INSIST(jitter <= sigvalidity);
  }

  if (jitter > sigvalidity) {
    jitter = sigvalidity;
  }

  if (sigvalidity >= 3600U) {
    if (sigvalidity > 7200U) {
      sigvalidity -= isc_random_uniform(jitter);
    } else {
      sigvalidity -= isc_random_uniform(1200);
    }
  }
  return sigvalidity;
}

isc_result_t
dns_update_signaturesinc(dns_update_log_t *log, dns_zone_t *zone, dns_db_t *db,
       dns_dbversion_t *oldver, dns_dbversion_t *newver,
       dns_diff_t *diff, uint32_t sigvalidityinterval,
       dns_update_state_t **statep) {
  isc_result_t result = ISC_R_SUCCESS;
  dns_update_state_t mystate, *state = NULL;
  dns_difftuple_t *tuple = NULL;
  bool flag, build_nsec;
  unsigned int i;
  dns_rdata_soa_t soa;
  dns_rdata_t rdata = DNS_RDATA_INIT;
  dns_rdataset_t rdataset;
  dns_dbnode_t *node = NULL;
  bool unsecure;
  bool cut;
  dns_rdatatype_t privatetype = dns_zone_getprivatetype(zone);
  unsigned int sigs = 0;
  unsigned int maxsigs = dns_zone_getsignatures(zone);

  if (statep == NULL || *statep == NULL) {
    if (statep == NULL) {
      state = &mystate;
    } else {
      state = isc_mem_get(diff->mctx, sizeof(*state));
    }

    dns_diff_init(diff->mctx, &state->diffnames);
    dns_diff_init(diff->mctx, &state->affected);
    dns_diff_init(diff->mctx, &state->sig_diff);
    dns_diff_init(diff->mctx, &state->nsec_diff);
    dns_diff_init(diff->mctx, &state->nsec_mindiff);
    dns_diff_init(diff->mctx, &state->work);
    state->nkeys = 0;
    state->build_nsec3 = false;

    result = find_zone_keys(zone, diff->mctx, DNS_MAXZONEKEYS,
          state->zone_keys, &state->nkeys);
    if (result == ISC_R_NOSPACE) {
      update_log(log, zone, ISC_LOG_ERROR,
           "too many zone keys for secure "
           "dynamic update");
    } else if (result != ISC_R_SUCCESS) {
      update_log(log, zone, ISC_LOG_ERROR,
           "could not get zone keys for secure "
           "dynamic update");
      goto cleanup;
    }

    state->now = isc_stdtime_now();
    state->inception = state->now - 3600; /* Allow for some clock
               skew. */
    state->expire = state->now + dns__jitter_expire(zone);
    state->soaexpire = state->now + sigvalidityinterval;
    state->keyexpire = dns_zone_getkeyvalidityinterval(zone);
    if (state->keyexpire == 0) {
      state->keyexpire = state->expire;
    } else {
      state->keyexpire += state->now;
    }

    /*
     * Calculate the NSEC/NSEC3 TTL as a minimum of the SOA TTL and
     * MINIMUM field.
     */
    CHECK(dns_db_findnode(db, dns_db_origin(db), false, &node));
    dns_rdataset_init(&rdataset);
    CHECK(dns_db_findrdataset(db, node, newver, dns_rdatatype_soa,
            0, (isc_stdtime_t)0, &rdataset,
            NULL));
    CHECK(dns_rdataset_first(&rdataset));
    dns_rdataset_current(&rdataset, &rdata);
    CHECK(dns_rdata_tostruct(&rdata, &soa, NULL));
    state->nsecttl = ISC_MIN(rdataset.ttl, soa.minimum);
    dns_rdataset_disassociate(&rdataset);
    dns_db_detachnode(&node);

    /*
     * Find all RRsets directly affected by the update, and
     * update their RRSIGs.  Also build a list of names affected
     * by the update in "diffnames".
     */
    CHECK(dns_diff_sort(diff, temp_order));
    state->state = sign_updates;
    state->magic = STATE_MAGIC;
    SET_IF_NOT_NULL(statep, state);
  } else {
    REQUIRE(DNS_STATE_VALID(*statep));
    state = *statep;
  }

next_state:
  switch (state->state) {
  case sign_updates:
    tuple = ISC_LIST_HEAD(diff->tuples);
    while (tuple != NULL) {
      dns_name_t *name = &tuple->name;
      dns_difftuple_t *next = NULL;

      /*
       * Now "name" is a new, unique name affected by the
       * update.
       */
      namelist_append_name(&state->diffnames, name);

      while (tuple != NULL &&
             dns_name_equal(&tuple->name, name))
      {
        dns_rdatatype_t type;
        type = tuple->rdata.type;

        /*
         * Now "name" and "type" denote a new unique
         * RRset affected by the update.
         */

        /* Don't sign RRSIGs. */
        if (type == dns_rdatatype_rrsig) {
          goto skip;
        }

        /*
         * Delete all old RRSIGs covering this type,
         * since they are all invalid when the signed
         * RRset has changed.  We may not be able to
         * recreate all of them - tough.
         * Special case changes to the zone's DNSKEY
         * records to support offline KSKs.
         */
        if (type == dns_rdatatype_dnskey) {
          del_keysigs(db, newver, name,
                &state->sig_diff,
                state->zone_keys,
                state->nkeys);
        } else {
          CHECK(delete_if(
            true_p, db, newver, name,
            dns_rdatatype_rrsig, type, NULL,
            &state->sig_diff));
        }

        /*
         * If this RRset is still visible after the
         * update, add a new signature for it.
         */
        CHECK(rrset_visible(db, newver, name, type,
                &flag));
        if (flag) {
          isc_stdtime_t exp;
          if (dns_rdatatype_iskeymaterial(type)) {
            exp = state->keyexpire;
          } else if (type == dns_rdatatype_soa) {
            exp = state->soaexpire;
          } else {
            exp = state->expire;
          }

          CHECK(add_sigs(log, zone, db, newver,
                   name, type,
                   &state->sig_diff,
                   state->zone_keys,
                   state->nkeys, state->now,
                   state->inception, exp));
          sigs++;
        }
      skip:
        /* Skip any other updates to the same RRset. */
        while (tuple != NULL &&
               dns_name_equal(&tuple->name, name) &&
               tuple->rdata.type == type)
        {
          next = ISC_LIST_NEXT(tuple, link);
          ISC_LIST_UNLINK(diff->tuples, tuple,
              link);
          ISC_LIST_APPEND(state->work.tuples,
              tuple, link);
          tuple = next;
        }
      }
      if (state != &mystate && sigs > maxsigs) {
        return DNS_R_CONTINUE;
      }
    }
    ISC_LIST_APPENDLIST(diff->tuples, state->work.tuples, link);

    update_log(log, zone, ISC_LOG_DEBUG(3),
         "updated data signatures");
    FALLTHROUGH;
  case remove_orphaned:
    state->state = remove_orphaned;

    /* Remove orphaned NSECs and RRSIG NSECs. */
    ISC_LIST_FOREACH(state->diffnames.tuples, t, link) {
      CHECK(non_nsec_rrset_exists(db, newver, &t->name,
                &flag));
      if (!flag) {
        CHECK(delete_if(true_p, db, newver, &t->name,
            dns_rdatatype_any, 0, NULL,
            &state->sig_diff));
      }
    }
    update_log(log, zone, ISC_LOG_DEBUG(3),
         "removed any orphaned NSEC records");

    /*
     * See if we need to build NSEC or NSEC3 chains.
     */
    CHECK(dns_private_chains(db, newver, privatetype, &build_nsec,
           &state->build_nsec3));
    if (!build_nsec) {
      state->state = update_nsec3;
      goto next_state;
    }

    update_log(log, zone, ISC_LOG_DEBUG(3),
         "rebuilding NSEC chain");

    FALLTHROUGH;
  case build_chain:
    state->state = build_chain;
    /*
     * When a name is created or deleted, its predecessor needs to
     * have its NSEC updated.
     */
    ISC_LIST_FOREACH(state->diffnames.tuples, t, link) {
      bool existed, exists;
      dns_fixedname_t fixedname;
      dns_name_t *prevname;

      prevname = dns_fixedname_initname(&fixedname);

      if (oldver != NULL) {
        CHECK(name_exists(db, oldver, &t->name,
              &existed));
      } else {
        existed = false;
      }
      CHECK(name_exists(db, newver, &t->name, &exists));
      if (exists == existed) {
        continue;
      }

      /*
       * Find the predecessor.
       * When names become obscured or unobscured in this
       * update transaction, we may find the wrong
       * predecessor because the NSECs have not yet been
       * updated to reflect the delegation change.  This
       * should not matter because in this case, the correct
       * predecessor is either the delegation node or a
       * newly unobscured node, and those nodes are on the
       * "affected" list in any case.
       */
      CHECK(next_active(log, zone, db, newver, &t->name,
            prevname, false));
      namelist_append_name(&state->affected, prevname);
    }

    /*
     * Find names potentially affected by delegation changes
     * (obscured by adding an NS or DNAME, or unobscured by
     * removing one).
     */
    ISC_LIST_FOREACH(state->diffnames.tuples, t, link) {
      bool ns_existed, dname_existed;
      bool ns_exists, dname_exists;

      if (oldver != NULL) {
        CHECK(rrset_exists(db, oldver, &t->name,
               dns_rdatatype_ns, 0,
               &ns_existed));
      } else {
        ns_existed = false;
      }
      if (oldver != NULL) {
        CHECK(rrset_exists(db, oldver, &t->name,
               dns_rdatatype_dname, 0,
               &dname_existed));
      } else {
        dname_existed = false;
      }
      CHECK(rrset_exists(db, newver, &t->name,
             dns_rdatatype_ns, 0, &ns_exists));
      CHECK(rrset_exists(db, newver, &t->name,
             dns_rdatatype_dname, 0,
             &dname_exists));
      if ((ns_exists || dname_exists) ==
          (ns_existed || dname_existed))
      {
        continue;
      }
      /*
       * There was a delegation change.  Mark all subdomains
       * of t->name as potentially needing a NSEC update.
       */
      CHECK(namelist_append_subdomain(db, &t->name,
              &state->affected));
    }
    ISC_LIST_APPENDLIST(state->affected.tuples,
            state->diffnames.tuples, link);
    INSIST(ISC_LIST_EMPTY(state->diffnames.tuples));

    CHECK(uniqify_name_list(&state->affected));

    FALLTHROUGH;
  case process_nsec:
    state->state = process_nsec;

    /*
     * Determine which names should have NSECs, and delete/create
     * NSECs to make it so.  We don't know the final NSEC targets
     * yet, so we just create placeholder NSECs with arbitrary
     * contents to indicate that their respective owner names
     * should be part of the NSEC chain.
     */
    ISC_LIST_FOREACH(state->affected.tuples, t, link) {
      bool exists;
      dns_name_t *name = &t->name;

      CHECK(name_exists(db, newver, name, &exists));
      if (!exists) {
        goto unlink;
      }
      CHECK(is_active(db, newver, name, &flag, &cut, NULL));
      if (!flag) {
        /*
         * This name is obscured.  Delete any
         * existing NSEC record.
         */
        CHECK(delete_if(true_p, db, newver, name,
            dns_rdatatype_nsec, 0, NULL,
            &state->nsec_diff));
        CHECK(delete_if(rrsig_p, db, newver, name,
            dns_rdatatype_any, 0, NULL,
            diff));
      } else {
        /*
         * This name is not obscured.  It needs to have
         * a NSEC unless it is the at the origin, in
         * which case it should already exist if there
         * is a complete NSEC chain and if there isn't
         * a complete NSEC chain we don't want to add
         * one as that would signal that there is a
         * complete NSEC chain.
         */
        if (!dns_name_equal(name, dns_db_origin(db))) {
          CHECK(rrset_exists(db, newver, name,
                 dns_rdatatype_nsec,
                 0, &flag));
          if (!flag) {
            CHECK(add_placeholder_nsec(
              db, newver, name,
              diff));
          }
        }
        CHECK(add_exposed_sigs(
          log, zone, db, newver, name, cut,
          &state->sig_diff, state->zone_keys,
          state->nkeys, state->now,
          state->inception, state->expire,
          &sigs));
      }
    unlink:
      ISC_LIST_UNLINK(state->affected.tuples, t, link);
      ISC_LIST_APPEND(state->work.tuples, t, link);
      if (state != &mystate && sigs > maxsigs) {
        return DNS_R_CONTINUE;
      }
    }
    ISC_LIST_APPENDLIST(state->affected.tuples, state->work.tuples,
            link);

    /*
     * Now we know which names are part of the NSEC chain.
     * Make them all point at their correct targets.
     */
    ISC_LIST_FOREACH(state->affected.tuples, t, link) {
      CHECK(rrset_exists(db, newver, &t->name,
             dns_rdatatype_nsec, 0, &flag));
      if (flag) {
        /*
         * There is a NSEC, but we don't know if it
         * is correct. Delete it and create a correct
         * one to be sure. If the update was
         * unnecessary, the diff minimization
         * will take care of eliminating it from the
         * journal, IXFRs, etc.
         *
         * The RRSIG bit should always be set in the
         * NSECs we generate, because they will all
         * get RRSIG NSECs.
         * (XXX what if the zone keys are missing?).
         * Because the RRSIG NSECs have not necessarily
         * been created yet, the correctness of the
         * bit mask relies on the assumption that NSECs
         * are only created if there is other data, and
         * if there is other data, there are other
         * RRSIGs.
         */
        CHECK(add_nsec(log, zone, db, newver, &t->name,
                 state->nsecttl,
                 &state->nsec_diff));
      }
    }

    /*
     * Minimize the set of NSEC updates so that we don't
     * have to regenerate the RRSIG NSECs for NSECs that were
     * replaced with identical ones.
     */
    ISC_LIST_FOREACH(state->nsec_diff.tuples, t, link) {
      ISC_LIST_UNLINK(state->nsec_diff.tuples, t, link);
      dns_diff_appendminimal(&state->nsec_mindiff, &t);
    }

    update_log(log, zone, ISC_LOG_DEBUG(3),
         "signing rebuilt NSEC chain");

    FALLTHROUGH;
  case sign_nsec:
    state->state = sign_nsec;
    /* Update RRSIG NSECs. */
    ISC_LIST_FOREACH(state->nsec_mindiff.tuples, t, link) {
      if (t->op == DNS_DIFFOP_DEL) {
        CHECK(delete_if(true_p, db, newver, &t->name,
            dns_rdatatype_rrsig,
            dns_rdatatype_nsec, NULL,
            &state->sig_diff));
      } else if (t->op == DNS_DIFFOP_ADD) {
        CHECK(add_sigs(log, zone, db, newver, &t->name,
                 dns_rdatatype_nsec,
                 &state->sig_diff,
                 state->zone_keys, state->nkeys,
                 state->now, state->inception,
                 state->expire));
        sigs++;
      } else {
        UNREACHABLE();
      }
      ISC_LIST_UNLINK(state->nsec_mindiff.tuples, t, link);
      ISC_LIST_APPEND(state->work.tuples, t, link);
      if (state != &mystate && sigs > maxsigs) {
        return DNS_R_CONTINUE;
      }
    }
    ISC_LIST_APPENDLIST(state->nsec_mindiff.tuples,
            state->work.tuples, link);
    FALLTHROUGH;
  case update_nsec3:
    state->state = update_nsec3;

    /* Record our changes for the journal. */
    ISC_LIST_FOREACH(state->sig_diff.tuples, t, link) {
      ISC_LIST_UNLINK(state->sig_diff.tuples, t, link);
      dns_diff_appendminimal(diff, &t);
    }
    ISC_LIST_FOREACH(state->nsec_mindiff.tuples, t, link) {
      ISC_LIST_UNLINK(state->nsec_mindiff.tuples, t, link);
      dns_diff_appendminimal(diff, &t);
    }

    INSIST(ISC_LIST_EMPTY(state->sig_diff.tuples));
    INSIST(ISC_LIST_EMPTY(state->nsec_diff.tuples));
    INSIST(ISC_LIST_EMPTY(state->nsec_mindiff.tuples));

    if (!state->build_nsec3) {
      update_log(log, zone, ISC_LOG_DEBUG(3),
           "no NSEC3 chains to rebuild");
      goto cleanup;
    }

    update_log(log, zone, ISC_LOG_DEBUG(3),
         "rebuilding NSEC3 chains");

    dns_diff_clear(&state->diffnames);
    dns_diff_clear(&state->affected);

    CHECK(dns_diff_sort(diff, temp_order));

    /*
     * Find names potentially affected by delegation changes
     * (obscured by adding an NS or DNAME, or unobscured by
     * removing one).
     */
    tuple = ISC_LIST_HEAD(diff->tuples);
    while (tuple != NULL) {
      dns_name_t *name = &tuple->name;

      bool ns_existed, dname_existed;
      bool ns_exists, dname_exists;
      bool exists, existed;

      if (tuple->rdata.type == dns_rdatatype_nsec ||
          tuple->rdata.type == dns_rdatatype_rrsig)
      {
        tuple = ISC_LIST_NEXT(tuple, link);
        continue;
      }

      namelist_append_name(&state->affected, name);

      if (oldver != NULL) {
        CHECK(rrset_exists(db, oldver, name,
               dns_rdatatype_ns, 0,
               &ns_existed));
      } else {
        ns_existed = false;
      }
      if (oldver != NULL) {
        CHECK(rrset_exists(db, oldver, name,
               dns_rdatatype_dname, 0,
               &dname_existed));
      } else {
        dname_existed = false;
      }
      CHECK(rrset_exists(db, newver, name, dns_rdatatype_ns,
             0, &ns_exists));
      CHECK(rrset_exists(db, newver, name,
             dns_rdatatype_dname, 0,
             &dname_exists));

      exists = ns_exists || dname_exists;
      existed = ns_existed || dname_existed;
      if (exists == existed) {
        goto nextname;
      }
      /*
       * There was a delegation change.  Mark all subdomains
       * of tuple->name as potentially needing a NSEC3 update.
       */
      CHECK(namelist_append_subdomain(db, name,
              &state->affected));

    nextname:
      while (tuple != NULL &&
             dns_name_equal(&tuple->name, name))
      {
        tuple = ISC_LIST_NEXT(tuple, link);
      }
    }

    FALLTHROUGH;
  case process_nsec3:
    state->state = process_nsec3;
    ISC_LIST_FOREACH(state->affected.tuples, t, link) {
      dns_name_t *name = &t->name;

      unsecure = false; /* Silence compiler warning. */
      CHECK(is_active(db, newver, name, &flag, &cut,
          &unsecure));

      if (!flag) {
        CHECK(delete_if(rrsig_p, db, newver, name,
            dns_rdatatype_any, 0, NULL,
            diff));
        CHECK(dns_nsec3_delnsec3sx(db, newver, name,
                 privatetype,
                 &state->nsec_diff));
      } else {
        CHECK(add_exposed_sigs(
          log, zone, db, newver, name, cut,
          &state->sig_diff, state->zone_keys,
          state->nkeys, state->now,
          state->inception, state->expire,
          &sigs));
        CHECK(dns_nsec3_addnsec3sx(
          db, newver, name, state->nsecttl,
          unsecure, privatetype,
          &state->nsec_diff));
      }
      ISC_LIST_UNLINK(state->affected.tuples, t, link);
      ISC_LIST_APPEND(state->work.tuples, t, link);
      if (state != &mystate && sigs > maxsigs) {
        return DNS_R_CONTINUE;
      }
    }
    ISC_LIST_APPENDLIST(state->affected.tuples, state->work.tuples,
            link);

    /*
     * Minimize the set of NSEC3 updates so that we don't
     * have to regenerate the RRSIG NSEC3s for NSEC3s that were
     * replaced with identical ones.
     */
    ISC_LIST_FOREACH(state->nsec_diff.tuples, t, link) {
      ISC_LIST_UNLINK(state->nsec_diff.tuples, t, link);
      dns_diff_appendminimal(&state->nsec_mindiff, &t);
    }

    update_log(log, zone, ISC_LOG_DEBUG(3),
         "signing rebuilt NSEC3 chain");

    FALLTHROUGH;
  case sign_nsec3:
    state->state = sign_nsec3;
    /* Update RRSIG NSEC3s. */
    ISC_LIST_FOREACH(state->nsec_mindiff.tuples, t, link) {
      if (t->op == DNS_DIFFOP_DEL) {
        CHECK(delete_if(true_p, db, newver, &t->name,
            dns_rdatatype_rrsig,
            dns_rdatatype_nsec3, NULL,
            &state->sig_diff));
      } else if (t->op == DNS_DIFFOP_ADD) {
        CHECK(add_sigs(log, zone, db, newver, &t->name,
                 dns_rdatatype_nsec3,
                 &state->sig_diff,
                 state->zone_keys, state->nkeys,
                 state->now, state->inception,
                 state->expire));
        sigs++;
      } else {
        UNREACHABLE();
      }
      ISC_LIST_UNLINK(state->nsec_mindiff.tuples, t, link);
      ISC_LIST_APPEND(state->work.tuples, t, link);
      if (state != &mystate && sigs > maxsigs) {
        return DNS_R_CONTINUE;
      }
    }
    ISC_LIST_APPENDLIST(state->nsec_mindiff.tuples,
            state->work.tuples, link);

    /* Record our changes for the journal. */
    ISC_LIST_FOREACH(state->sig_diff.tuples, t, link) {
      ISC_LIST_UNLINK(state->sig_diff.tuples, t, link);
      dns_diff_appendminimal(diff, &t);
    }
    ISC_LIST_FOREACH(state->nsec_mindiff.tuples, t, link) {
      ISC_LIST_UNLINK(state->nsec_mindiff.tuples, t, link);
      dns_diff_appendminimal(diff, &t);
    }

    INSIST(ISC_LIST_EMPTY(state->sig_diff.tuples));
    INSIST(ISC_LIST_EMPTY(state->nsec_diff.tuples));
    INSIST(ISC_LIST_EMPTY(state->nsec_mindiff.tuples));
    break;
  default:
    UNREACHABLE();
  }

cleanup:
  if (node != NULL) {
    dns_db_detachnode(&node);
  }

  dns_diff_clear(&state->sig_diff);
  dns_diff_clear(&state->nsec_diff);
  dns_diff_clear(&state->nsec_mindiff);

  dns_diff_clear(&state->affected);
  dns_diff_clear(&state->diffnames);
  dns_diff_clear(&state->work);

  for (i = 0; i < state->nkeys; i++) {
    dst_key_free(&state->zone_keys[i]);
  }

  if (state != &mystate) {
    *statep = NULL;
    state->magic = 0;
    isc_mem_put(diff->mctx, state, sizeof(*state));
  }

  return result;
}

static isc_stdtime_t
epoch_to_yyyymmdd(time_t when) {
  struct tm t, *tm = localtime_r(&when, &t);
  if (tm == NULL) {
    return 0;
  }
  return ((tm->tm_year + 1900) * 10000) + ((tm->tm_mon + 1) * 100) +
         tm->tm_mday;
}

static uint32_t
dns__update_soaserial(uint32_t serial, dns_updatemethod_t method) {
  isc_stdtime_t now;

  switch (method) {
  case dns_updatemethod_none:
    return serial;
  case dns_updatemethod_unixtime:
    now = isc_stdtime_now();
    return now;
  case dns_updatemethod_date:
    now = isc_stdtime_now();
    return epoch_to_yyyymmdd((time_t)now) * 100;
  case dns_updatemethod_increment:
    /* RFC1982 */
    serial = (serial + 1) & 0xFFFFFFFF;
    if (serial == 0) {
      return 1;
    }
    return serial;
  default:
    UNREACHABLE();
  }
}

uint32_t
dns_update_soaserial(uint32_t serial, dns_updatemethod_t method,
         dns_updatemethod_t *used) {
  uint32_t new_serial = dns__update_soaserial(serial, method);
  switch (method) {
  case dns_updatemethod_none:
  case dns_updatemethod_increment:
    break;
  case dns_updatemethod_unixtime:
  case dns_updatemethod_date:
    if (!(new_serial != 0 && isc_serial_gt(new_serial, serial))) {
      /*
       * If the new date serial following YYYYMMDD00 is equal
       * to or smaller than the current serial, but YYYYMMDD99
       * would be larger, pretend we have used the
       * "dns_updatemethod_date" method.
       */
      if (method == dns_updatemethod_unixtime ||
          !isc_serial_gt(new_serial + 99, serial))
      {
        method = dns_updatemethod_increment;
      }
      new_serial = dns__update_soaserial(
        serial, dns_updatemethod_increment);
    }
    break;
  default:
    UNREACHABLE();
  }

  SET_IF_NOT_NULL(used, method);

  return new_serial;
}

Coverage Report

Created: 2026-06-15 06:55