/src/bind9/lib/dns/rdataslab.c

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/*
 * 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 <ctype.h>
#include <stdbool.h>
#include <stdlib.h>

#include <isc/ascii.h>
#include <isc/mem.h>
#include <isc/region.h>
#include <isc/result.h>
#include <isc/string.h>
#include <isc/util.h>

#include <dns/db.h>
#include <dns/rdata.h>
#include <dns/rdataset.h>
#include <dns/rdataslab.h>
#include <dns/stats.h>

#define CASESET(header)                                \
  ((atomic_load_acquire(&(header)->attributes) & \
    DNS_SLABHEADERATTR_CASESET) != 0)
#define CASEFULLYLOWER(header)                         \
  ((atomic_load_acquire(&(header)->attributes) & \
    DNS_SLABHEADERATTR_CASEFULLYLOWER) != 0)
#define NONEXISTENT(header)                            \
  ((atomic_load_acquire(&(header)->attributes) & \
    DNS_SLABHEADERATTR_NONEXISTENT) != 0)
#define NEGATIVE(header)                               \
  ((atomic_load_acquire(&(header)->attributes) & \
    DNS_SLABHEADERATTR_NEGATIVE) != 0)

/*
 * The rdataslab structure allows iteration to occur in both load order
 * and DNSSEC order.  The structure is as follows:
 *
 *  header    (dns_slabheader_t)
 *  record count  (2 bytes)
 *  offset table  (4 x record count bytes in load order)
 *  data records
 *    data length (2 bytes)
 *    order   (2 bytes)
 *    meta data (1 byte for RRSIG's)
 *    data    (data length bytes)
 *
 * A "raw" rdataslab is the same but without the header.
 *
 * DNSSEC order traversal is performed by walking the data records.
 *
 * The order is stored with record to allow for efficient reconstruction
 * of the offset table following a merge or subtraction.
 *
 * The iterator methods in rbtdb support both load order and DNSSEC order
 * iteration.
 *
 * WARNING:
 *  rbtdb.c directly interacts with the slab's raw structures.  If the
 *  structure changes then rbtdb.c also needs to be updated to reflect
 *  the changes.  See the areas tagged with "RDATASLAB".
 */

#define peek_uint16(buffer) ({ ((uint16_t)*(buffer) << 8) | *((buffer) + 1); })
#define get_uint16(buffer)                            \
  ({                                            \
    uint16_t __ret = peek_uint16(buffer); \
    buffer += sizeof(uint16_t);           \
    __ret;                                \
  })
#define put_uint16(buffer, val)                  \
  ({                                       \
    *buffer++ = (val & 0xff00) >> 8; \
    *buffer++ = (val & 0x00ff);      \
  })

static void
rdataset_disassociate(dns_rdataset_t *rdataset DNS__DB_FLARG);
static isc_result_t
rdataset_first(dns_rdataset_t *rdataset);
static isc_result_t
rdataset_next(dns_rdataset_t *rdataset);
static void
rdataset_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata);
static void
rdataset_clone(dns_rdataset_t *source, dns_rdataset_t *target DNS__DB_FLARG);
static unsigned int
rdataset_count(dns_rdataset_t *rdataset);
static isc_result_t
rdataset_getnoqname(dns_rdataset_t *rdataset, dns_name_t *name,
        dns_rdataset_t *neg, dns_rdataset_t *negsig DNS__DB_FLARG);
static isc_result_t
rdataset_getclosest(dns_rdataset_t *rdataset, dns_name_t *name,
        dns_rdataset_t *neg, dns_rdataset_t *negsig DNS__DB_FLARG);
static void
rdataset_settrust(dns_rdataset_t *rdataset, dns_trust_t trust);
static void
rdataset_expire(dns_rdataset_t *rdataset DNS__DB_FLARG);
static void
rdataset_clearprefetch(dns_rdataset_t *rdataset);
static void
rdataset_setownercase(dns_rdataset_t *rdataset, const dns_name_t *name);
static void
rdataset_getownercase(const dns_rdataset_t *rdataset, dns_name_t *name);
static dns_slabheader_t *
rdataset_getheader(const dns_rdataset_t *rdataset);
static bool
rdataset_equals(const dns_rdataset_t *rdataset1,
    const dns_rdataset_t *rdataset2);

dns_rdatasetmethods_t dns_rdataslab_rdatasetmethods = {
  .disassociate = rdataset_disassociate,
  .first = rdataset_first,
  .next = rdataset_next,
  .current = rdataset_current,
  .clone = rdataset_clone,
  .count = rdataset_count,
  .getnoqname = rdataset_getnoqname,
  .getclosest = rdataset_getclosest,
  .settrust = rdataset_settrust,
  .expire = rdataset_expire,
  .clearprefetch = rdataset_clearprefetch,
  .setownercase = rdataset_setownercase,
  .getownercase = rdataset_getownercase,
  .getheader = rdataset_getheader,
  .equals = rdataset_equals,
};

/*% Note: the "const void *" are just to make qsort happy.  */
static int
compare_rdata(const void *p1, const void *p2) {
  return dns_rdata_compare(p1, p2);
}

static isc_result_t
makeslab(dns_rdataset_t *rdataset, isc_mem_t *mctx, isc_region_t *region,
   uint32_t maxrrperset) {
  /*
   * Use &removed as a sentinel pointer for duplicate
   * rdata as rdata.data == NULL is valid.
   */
  static unsigned char removed;
  dns_rdata_t *rdata = NULL;
  unsigned char *rawbuf = NULL;
  unsigned int headerlen = sizeof(dns_slabheader_t);
  unsigned int buflen = headerlen + 2;
  isc_result_t result;
  unsigned int nitems;
  unsigned int nalloc;
  unsigned int length;
  size_t i;
  size_t rdatasize;

  /*
   * If the source rdataset is also a slab, we don't need
   * to do anything special, just copy the whole slab to a
   * new buffer.
   */
  if (rdataset->methods == &dns_rdataslab_rdatasetmethods) {
    dns_slabheader_t *header = dns_rdataset_getheader(rdataset);
    buflen = dns_rdataslab_size(header);

    rawbuf = isc_mem_get(mctx, buflen);
    region->base = rawbuf;
    region->length = buflen;

    memmove(rawbuf, header, buflen);
    return ISC_R_SUCCESS;
  }

  /*
   * If there are no rdata then we just need to allocate a header
   * with a zero record count.
   */
  nitems = dns_rdataset_count(rdataset);
  if (nitems == 0) {
    if (rdataset->type != 0) {
      return ISC_R_FAILURE;
    }
    rawbuf = isc_mem_get(mctx, buflen);
    region->base = rawbuf;
    region->length = buflen;
    rawbuf += headerlen;
    put_uint16(rawbuf, 0);
    return ISC_R_SUCCESS;
  }

  if (maxrrperset > 0 && nitems > maxrrperset) {
    return DNS_R_TOOMANYRECORDS;
  }

  if (nitems > 0xffff) {
    return ISC_R_NOSPACE;
  }

  /*
   * Remember the original number of items.
   */
  nalloc = nitems;

  RUNTIME_CHECK(!ISC_OVERFLOW_MUL(nalloc, sizeof(rdata[0]), &rdatasize));
  rdata = isc_mem_get(mctx, rdatasize);

  /*
   * Save all of the rdata members into an array.
   */
  result = dns_rdataset_first(rdataset);
  if (result != ISC_R_SUCCESS && result != ISC_R_NOMORE) {
    goto free_rdatas;
  }
  for (i = 0; i < nalloc && result == ISC_R_SUCCESS; i++) {
    INSIST(result == ISC_R_SUCCESS);
    dns_rdata_init(&rdata[i]);
    dns_rdataset_current(rdataset, &rdata[i]);
    INSIST(rdata[i].data != &removed);
    result = dns_rdataset_next(rdataset);
  }
  if (i != nalloc || result != ISC_R_NOMORE) {
    /*
     * Somehow we iterated over fewer rdatas than
     * dns_rdataset_count() said there were or there
     * were more items than dns_rdataset_count said
     * there were.
     */
    result = ISC_R_FAILURE;
    goto free_rdatas;
  }

  /*
   * Put into DNSSEC order.
   */
  if (nalloc > 1U) {
    qsort(rdata, nalloc, sizeof(rdata[0]), compare_rdata);
  }

  /*
   * Remove duplicates and compute the total storage required.
   *
   * If an rdata is not a duplicate, accumulate the storage size
   * required for the rdata.  We do not store the class, type, etc,
   * just the rdata, so our overhead is 2 bytes for the number of
   * records, and 8 for each rdata, (length(2), offset(4) and order(2))
   * and then the rdata itself.
   */
  for (i = 1; i < nalloc; i++) {
    if (compare_rdata(&rdata[i - 1], &rdata[i]) == 0) {
      rdata[i - 1].data = &removed;
      nitems--;
    } else {
      buflen += (2 + rdata[i - 1].length);
      /*
       * Provide space to store the per RR meta data.
       */
      if (rdataset->type == dns_rdatatype_rrsig) {
        buflen++;
      }
    }
  }

  /*
   * Don't forget the last item!
   */
  buflen += (2 + rdata[i - 1].length);

  /*
   * Provide space to store the per RR meta data.
   */
  if (rdataset->type == dns_rdatatype_rrsig) {
    buflen++;
  }

  /*
   * Ensure that singleton types are actually singletons.
   */
  if (nitems > 1 && dns_rdatatype_issingleton(rdataset->type)) {
    /*
     * We have a singleton type, but there's more than one
     * RR in the rdataset.
     */
    result = DNS_R_SINGLETON;
    goto free_rdatas;
  }

  /*
   * Allocate the memory, set up a buffer, start copying in
   * data.
   */
  rawbuf = isc_mem_get(mctx, buflen);

  region->base = rawbuf;
  region->length = buflen;
  rawbuf += headerlen;
  put_uint16(rawbuf, nitems);

  for (i = 0; i < nalloc; i++) {
    if (rdata[i].data == &removed) {
      continue;
    }
    length = rdata[i].length;
    if (rdataset->type == dns_rdatatype_rrsig) {
      length++;
    }
    INSIST(length <= 0xffff);

    put_uint16(rawbuf, length);

    /*
     * Store the per RR meta data.
     */
    if (rdataset->type == dns_rdatatype_rrsig) {
      *rawbuf++ = (rdata[i].flags & DNS_RDATA_OFFLINE)
              ? DNS_RDATASLAB_OFFLINE
              : 0;
    }
    if (rdata[i].length != 0) {
      memmove(rawbuf, rdata[i].data, rdata[i].length);
    }
    rawbuf += rdata[i].length;
  }

  result = ISC_R_SUCCESS;

free_rdatas:
  isc_mem_put(mctx, rdata, rdatasize);
  return result;
}

isc_result_t
dns_rdataslab_fromrdataset(dns_rdataset_t *rdataset, isc_mem_t *mctx,
         isc_region_t *region, uint32_t maxrrperset) {
  isc_result_t result;

  result = makeslab(rdataset, mctx, region, maxrrperset);
  if (result == ISC_R_SUCCESS) {
    dns_slabheader_t *new = (dns_slabheader_t *)region->base;

    *new = (dns_slabheader_t){
      .type = DNS_TYPEPAIR_VALUE(rdataset->type,
               rdataset->covers),
      .trust = rdataset->trust,
      .ttl = rdataset->ttl,
      .link = ISC_LINK_INITIALIZER,
    };
  }

  return result;
}

unsigned int
dns_rdataslab_size(dns_slabheader_t *header) {
  REQUIRE(header != NULL);

  unsigned char *slab = (unsigned char *)header +
            sizeof(dns_slabheader_t);
  INSIST(slab != NULL);

  unsigned char *current = slab;
  uint16_t count = get_uint16(current);

  while (count-- > 0) {
    uint16_t length = get_uint16(current);
    current += length;
  }

  return (unsigned int)(current - slab) + sizeof(dns_slabheader_t);
}

unsigned int
dns_rdataslab_count(dns_slabheader_t *header) {
  REQUIRE(header != NULL);

  unsigned char *current = (unsigned char *)header + sizeof(*header);
  uint16_t count = get_uint16(current);

  return count;
}

/*
 * Make the dns_rdata_t 'rdata' refer to the slab item
 * beginning at '*current', which is part of a slab of type
 * 'type' and class 'rdclass', and advance '*current' to
 * point to the next item in the slab.
 */
static void
rdata_from_slabitem(unsigned char **current, dns_rdataclass_t rdclass,
        dns_rdatatype_t type, dns_rdata_t *rdata) {
  unsigned char *tcurrent = *current;
  isc_region_t region;
  bool offline = false;
  uint16_t length = get_uint16(tcurrent);

  if (type == dns_rdatatype_rrsig) {
    if ((*tcurrent & DNS_RDATASLAB_OFFLINE) != 0) {
      offline = true;
    }
    length--;
    tcurrent++;
  }
  region.length = length;
  region.base = tcurrent;
  tcurrent += region.length;
  dns_rdata_fromregion(rdata, rdclass, type, &region);
  if (offline) {
    rdata->flags |= DNS_RDATA_OFFLINE;
  }
  *current = tcurrent;
}

static void
rdata_to_slabitem(unsigned char **current, dns_rdatatype_t type,
      dns_rdata_t *rdata) {
  unsigned int length = rdata->length;
  unsigned char *data = rdata->data;
  unsigned char *p = *current;

  if (type == dns_rdatatype_rrsig) {
    length++;
    data--;
  }

  put_uint16(p, length);
  memmove(p, data, length);
  p += length;

  *current = p;
}

typedef struct slabinfo {
  unsigned char *pos;
  dns_rdata_t rdata;
  bool dup;
} slabinfo_t;

isc_result_t
dns_rdataslab_merge(dns_slabheader_t *oheader, dns_slabheader_t *nheader,
        isc_mem_t *mctx, dns_rdataclass_t rdclass,
        dns_rdatatype_t type, unsigned int flags,
        uint32_t maxrrperset, dns_slabheader_t **theaderp) {
  isc_result_t result = ISC_R_SUCCESS;
  unsigned char *ocurrent = NULL, *ncurrent = NULL, *tcurrent = NULL;
  unsigned int ocount, ncount, tlength, tcount = 0;
  slabinfo_t *oinfo = NULL, *ninfo = NULL;
  size_t o = 0, n = 0;

  REQUIRE(theaderp != NULL && *theaderp == NULL);
  REQUIRE(oheader != NULL && nheader != NULL);

  ocurrent = (unsigned char *)oheader + sizeof(dns_slabheader_t);
  ocount = get_uint16(ocurrent);

  ncurrent = (unsigned char *)nheader + sizeof(dns_slabheader_t);
  ncount = get_uint16(ncurrent);

  INSIST(ocount > 0 && ncount > 0);

  if (maxrrperset > 0 && ocount + ncount > maxrrperset) {
    return DNS_R_TOOMANYRECORDS;
  }

  /*
   * Figure out the target length. Start with the header,
   * plus 2 octets for the count.
   */
  tlength = sizeof(dns_slabheader_t) + 2;

  /*
   * Gather the rdatas in the old slab and add their lengths to
   * the larget length.
   */
  oinfo = isc_mem_cget(mctx, ocount, sizeof(struct slabinfo));
  for (size_t i = 0; i < ocount; i++) {
    oinfo[i].pos = ocurrent;
    dns_rdata_init(&oinfo[i].rdata);
    rdata_from_slabitem(&ocurrent, rdclass, type, &oinfo[i].rdata);
    tlength += ocurrent - oinfo[i].pos;
  }

  /*
   * Then add the length of rdatas in the new slab that aren't
   * duplicated in the old slab.
   */
  ninfo = isc_mem_cget(mctx, ncount, sizeof(struct slabinfo));
  for (size_t i = 0; i < ncount; i++) {
    ninfo[i].pos = ncurrent;
    dns_rdata_init(&ninfo[i].rdata);
    rdata_from_slabitem(&ncurrent, rdclass, type, &ninfo[i].rdata);

    for (size_t j = 0; j < ocount; j++) {
      if (oinfo[j].dup) {
        /*
         * This was already found to be
         * duplicated; no need to compare
         * it again.
         */
        continue;
      }

      if (dns_rdata_compare(&oinfo[j].rdata,
                &ninfo[i].rdata) == 0)
      {
        /*
         * Found a dup. Mark the old copy as a
         * duplicate so we don't check it again;
         * mark the new copy as a duplicate so we
         * don't copy it to the target.
         */
        oinfo[j].dup = ninfo[i].dup = true;
        break;
      }
    }

    if (ninfo[i].dup) {
      continue;
    }

    /*
     * We will be copying this item to the target, so
     * add its length to tlength and increment tcount.
     */
    tlength += ncurrent - ninfo[i].pos;
    tcount++;
  }

  /*
   * If the EXACT flag is set, there can't be any rdata in
   * the new slab that was also in the old. If tcount is less
   * than ncount, then we found such a duplicate.
   */
  if (((flags & DNS_RDATASLAB_EXACT) != 0) && (tcount < ncount)) {
    result = DNS_R_NOTEXACT;
    goto cleanup;
  }

  /*
   * If nothing's being copied in from the new slab, and the
   * FORCE flag isn't set, we're done.
   */
  if (tcount == 0 && (flags & DNS_RDATASLAB_FORCE) == 0) {
    result = DNS_R_UNCHANGED;
    goto cleanup;
  }

  /* Add to tcount the total number of items from the old slab. */
  tcount += ocount;

  /* Resposition ncurrent at the first item. */
  ncurrent = (unsigned char *)nheader + sizeof(dns_slabheader_t) + 2;

  /* Single types can't have more than one RR. */
  if (tcount > 1 && dns_rdatatype_issingleton(type)) {
    result = DNS_R_SINGLETON;
    goto cleanup;
  }

  if (tcount > 0xffff) {
    result = ISC_R_NOSPACE;
    goto cleanup;
  }

  /* Allocate the target buffer and copy the new slab's header */
  unsigned char *tstart = isc_mem_get(mctx, tlength);

  memmove(tstart, nheader, sizeof(dns_slabheader_t));
  tcurrent = tstart + sizeof(dns_slabheader_t);

  /* Write the new count, then start merging the slabs. */
  put_uint16(tcurrent, tcount);

  /*
   * Now walk the sets together, adding each item in DNSSEC order,
   * and skipping over any more dups in the new slab.
   */
  while (o < ocount || n < ncount) {
    bool fromold;

    /* Skip to the next non-duplicate in the new slab. */
    for (; n < ncount && ninfo[n].dup; n++)
      ;

    if (o == ocount) {
      fromold = false;
    } else if (n == ncount) {
      fromold = true;
    } else {
      fromold = dns_rdata_compare(&oinfo[o].rdata,
                &ninfo[n].rdata) < 0;
    }

    if (fromold) {
      rdata_to_slabitem(&tcurrent, type, &oinfo[o].rdata);
      if (++o < ocount) {
        /* Skip to the next rdata in the old slab */
        continue;
      }
    } else {
      rdata_to_slabitem(&tcurrent, type, &ninfo[n++].rdata);
    }
  }

  INSIST(tcurrent == tstart + tlength);

  *theaderp = (dns_slabheader_t *)tstart;

cleanup:
  isc_mem_cput(mctx, oinfo, ocount, sizeof(struct slabinfo));
  isc_mem_cput(mctx, ninfo, ncount, sizeof(struct slabinfo));

  return result;
}

isc_result_t
dns_rdataslab_subtract(dns_slabheader_t *oheader, dns_slabheader_t *sheader,
           isc_mem_t *mctx, dns_rdataclass_t rdclass,
           dns_rdatatype_t type, unsigned int flags,
           dns_slabheader_t **theaderp) {
  isc_result_t result = ISC_R_SUCCESS;
  unsigned char *ocurrent = NULL, *scurrent = NULL;
  unsigned char *tstart = NULL, *tcurrent = NULL;
  unsigned int ocount, scount, tlength;
  unsigned int tcount = 0, rcount = 0;
  slabinfo_t *oinfo = NULL, *sinfo = NULL;

  REQUIRE(theaderp != NULL && *theaderp == NULL);
  REQUIRE(oheader != NULL && sheader != NULL);

  ocurrent = (unsigned char *)oheader + sizeof(dns_slabheader_t);
  ocount = get_uint16(ocurrent);

  scurrent = (unsigned char *)sheader + sizeof(dns_slabheader_t);
  scount = get_uint16(scurrent);

  INSIST(ocount > 0 && scount > 0);

  /* Get info about the rdatas being subtracted */
  sinfo = isc_mem_cget(mctx, scount, sizeof(struct slabinfo));
  for (size_t i = 0; i < scount; i++) {
    sinfo[i].pos = scurrent;
    dns_rdata_init(&sinfo[i].rdata);
    rdata_from_slabitem(&scurrent, rdclass, type, &sinfo[i].rdata);
  }

  /*
   * Figure out the target length. Start with the header,
   * plus 2 octets for the count.
   */
  tlength = sizeof(dns_slabheader_t) + 2;

  /*
   * Add the length of the rdatas in the old slab that
   * aren't being subtracted.
   */
  oinfo = isc_mem_cget(mctx, ocount, sizeof(struct slabinfo));
  for (size_t i = 0; i < ocount; i++) {
    bool matched = false;

    oinfo[i].pos = ocurrent;
    dns_rdata_init(&oinfo[i].rdata);
    rdata_from_slabitem(&ocurrent, rdclass, type, &oinfo[i].rdata);

    for (size_t j = 0; j < scount; j++) {
      if (sinfo[j].dup) {
        continue;
      } else if (dns_rdata_compare(&oinfo[i].rdata,
                 &sinfo[j].rdata) == 0)
      {
        matched = true;
        oinfo[i].dup = sinfo[j].dup = true;
        break;
      }
    }

    if (matched) {
      /* This item will be subtracted. */
      rcount++;
    } else {
      /*
       * This rdata wasn't in the slab to be subtracted,
       * so copy it to the target.  Add its length to
       * tlength and increment tcount.
       */
      tlength += ocurrent - oinfo[i].pos;
      tcount++;
    }
  }

  /*
   * If the EXACT flag wasn't set, check that all the records that
   * were to be subtracted actually did exist in the original slab.
   * (The numeric check works here because rdataslabs do not contain
   * duplicates.)
   */
  if ((flags & DNS_RDATASLAB_EXACT) != 0 && rcount != scount) {
    result = DNS_R_NOTEXACT;
    goto cleanup;
  }

  /*
   * If the resulting rdataslab would be empty, don't bother to
   * create a new buffer, just return.
   */
  if (tcount == 0) {
    result = DNS_R_NXRRSET;
    goto cleanup;
  }

  /*
   * If nothing is going to change, stop.
   */
  if (rcount == 0) {
    result = DNS_R_UNCHANGED;
    goto cleanup;
  }

  /*
   * Allocate the target buffer and copy the old slab's header.
   */
  tstart = isc_mem_get(mctx, tlength);
  memmove(tstart, oheader, sizeof(dns_slabheader_t));
  tcurrent = tstart + sizeof(dns_slabheader_t);

  /*
   * Write the new count.
   */
  put_uint16(tcurrent, tcount);

  /*
   * Copy the parts of the old slab that didn't have duplicates.
   */
  for (size_t i = 0; i < ocount; i++) {
    if (!oinfo[i].dup) {
      rdata_to_slabitem(&tcurrent, type, &oinfo[i].rdata);
    }
  }

  INSIST(tcurrent == tstart + tlength);

  *theaderp = (dns_slabheader_t *)tstart;

cleanup:
  isc_mem_cput(mctx, oinfo, ocount, sizeof(struct slabinfo));
  isc_mem_cput(mctx, sinfo, scount, sizeof(struct slabinfo));

  return result;
}

bool
dns_rdataslab_equal(dns_slabheader_t *slab1, dns_slabheader_t *slab2) {
  unsigned char *current1 = NULL, *current2 = NULL;
  unsigned int count1, count2;

  current1 = (unsigned char *)slab1 + sizeof(dns_slabheader_t);
  count1 = get_uint16(current1);

  current2 = (unsigned char *)slab2 + sizeof(dns_slabheader_t);
  count2 = get_uint16(current2);

  if (count1 != count2) {
    return false;
  } else if (count1 == 0) {
    return true;
  }

  while (count1-- > 0) {
    unsigned int length1 = get_uint16(current1);
    unsigned int length2 = get_uint16(current2);

    if (length1 != length2 ||
        memcmp(current1, current2, length1) != 0)
    {
      return false;
    }

    current1 += length1;
    current2 += length1;
  }
  return true;
}

bool
dns_rdataslab_equalx(dns_slabheader_t *slab1, dns_slabheader_t *slab2,
         dns_rdataclass_t rdclass, dns_rdatatype_t type) {
  unsigned char *current1 = NULL, *current2 = NULL;
  unsigned int count1, count2;

  current1 = (unsigned char *)slab1 + sizeof(dns_slabheader_t);
  count1 = get_uint16(current1);

  current2 = (unsigned char *)slab2 + sizeof(dns_slabheader_t);
  count2 = get_uint16(current2);

  if (count1 != count2) {
    return false;
  } else if (count1 == 0) {
    return true;
  }

  while (count1-- > 0) {
    dns_rdata_t rdata1 = DNS_RDATA_INIT;
    dns_rdata_t rdata2 = DNS_RDATA_INIT;

    rdata_from_slabitem(&current1, rdclass, type, &rdata1);
    rdata_from_slabitem(&current2, rdclass, type, &rdata2);
    if (dns_rdata_compare(&rdata1, &rdata2) != 0) {
      return false;
    }
  }
  return true;
}

void *
dns_slabheader_raw(dns_slabheader_t *header) {
  return header + 1;
}

void
dns_slabheader_setownercase(dns_slabheader_t *header, const dns_name_t *name) {
  unsigned int i;
  bool fully_lower;

  /*
   * We do not need to worry about label lengths as they are all
   * less than or equal to 63.
   */
  memset(header->upper, 0, sizeof(header->upper));
  fully_lower = true;
  for (i = 0; i < name->length; i++) {
    if (isupper(name->ndata[i])) {
      header->upper[i / 8] |= 1 << (i % 8);
      fully_lower = false;
    }
  }
  DNS_SLABHEADER_SETATTR(header, DNS_SLABHEADERATTR_CASESET);
  if (fully_lower) {
    DNS_SLABHEADER_SETATTR(header,
               DNS_SLABHEADERATTR_CASEFULLYLOWER);
  }
}

void
dns_slabheader_copycase(dns_slabheader_t *dest, dns_slabheader_t *src) {
  if (CASESET(src)) {
    uint_least16_t attr = DNS_SLABHEADER_GETATTR(
      src, DNS_SLABHEADERATTR_CASESET |
             DNS_SLABHEADERATTR_CASEFULLYLOWER);
    DNS_SLABHEADER_SETATTR(dest, attr);
    memmove(dest->upper, src->upper, sizeof(src->upper));
  }
}

void
dns_slabheader_reset(dns_slabheader_t *h, dns_db_t *db, dns_dbnode_t *node) {
  ISC_LINK_INIT(h, link);
  h->heap_index = 0;
  h->heap = NULL;
  h->db = db;
  h->node = node;
  h->visited = false;

  atomic_init(&h->attributes, 0);
  atomic_init(&h->last_refresh_fail_ts, 0);

  STATIC_ASSERT(sizeof(h->attributes) == 2,
          "The .attributes field of dns_slabheader_t needs to be "
          "16-bit int type exactly.");
}

dns_slabheader_t *
dns_slabheader_new(dns_db_t *db, dns_dbnode_t *node) {
  dns_slabheader_t *h = NULL;

  h = isc_mem_get(db->mctx, sizeof(*h));
  *h = (dns_slabheader_t){
    .link = ISC_LINK_INITIALIZER,
  };
  dns_slabheader_reset(h, db, node);
  return h;
}

void
dns_slabheader_destroy(dns_slabheader_t **headerp) {
  unsigned int size;
  dns_slabheader_t *header = *headerp;

  *headerp = NULL;

  isc_mem_t *mctx = header->db->mctx;

  dns_db_deletedata(header->db, header->node, header);

  if (NONEXISTENT(header)) {
    size = sizeof(*header);
  } else {
    size = dns_rdataslab_size(header);
  }

  isc_mem_put(mctx, header, size);
}

void
dns_slabheader_freeproof(isc_mem_t *mctx, dns_slabheader_proof_t **proofp) {
  unsigned int buflen;
  uint8_t *rawbuf;
  dns_slabheader_proof_t *proof = *proofp;
  *proofp = NULL;

  if (dns_name_dynamic(&proof->name)) {
    dns_name_free(&proof->name, mctx);
  }
  if (proof->neg != NULL) {
    rawbuf = proof->neg;
    rawbuf -= sizeof(dns_slabheader_t);
    buflen = dns_rdataslab_size((dns_slabheader_t *)rawbuf);

    isc_mem_put(mctx, rawbuf, buflen);
  }
  if (proof->negsig != NULL) {
    rawbuf = proof->negsig;
    rawbuf -= sizeof(dns_slabheader_t);
    buflen = dns_rdataslab_size((dns_slabheader_t *)rawbuf);

    isc_mem_put(mctx, rawbuf, buflen);
  }
  isc_mem_put(mctx, proof, sizeof(*proof));
}

dns_slabheader_t *
dns_slabheader_top(dns_slabheader_t *header) {
  dns_typepair_t type, negtype;
  dns_rdatatype_t rdtype, covers;

  type = header->type;
  rdtype = DNS_TYPEPAIR_TYPE(header->type);
  if (NEGATIVE(header)) {
    covers = DNS_TYPEPAIR_COVERS(header->type);
    negtype = DNS_TYPEPAIR_VALUE(covers, 0);
  } else {
    negtype = DNS_TYPEPAIR_VALUE(0, rdtype);
  }

  /*
   * Find the start of the header chain for the next type
   * by walking back up the list.
   */
  while (header->up != NULL &&
         (header->up->type == type || header->up->type == negtype))
  {
    header = header->up;
  }

  return header;
}

/* Fixed RRSet helper macros */

#define DNS_RDATASET_LENGTH 2;

static void
rdataset_disassociate(dns_rdataset_t *rdataset DNS__DB_FLARG) {
  dns_db_t *db = rdataset->slab.db;
  dns_dbnode_t *node = rdataset->slab.node;

  dns__db_detachnode(db, &node DNS__DB_FLARG_PASS);
}

static isc_result_t
rdataset_first(dns_rdataset_t *rdataset) {
  unsigned char *raw = rdataset->slab.raw;
  uint16_t count = peek_uint16(raw);
  if (count == 0) {
    rdataset->slab.iter_pos = NULL;
    rdataset->slab.iter_count = 0;
    return ISC_R_NOMORE;
  }

  /*
   * iter_count is the number of rdata beyond the cursor
   * position, so we decrement the total count by one before
   * storing it.
   *
   * 'raw' points to the first record.
   */
  rdataset->slab.iter_pos = raw + DNS_RDATASET_LENGTH;
  rdataset->slab.iter_count = count - 1;

  return ISC_R_SUCCESS;
}

static isc_result_t
rdataset_next(dns_rdataset_t *rdataset) {
  uint16_t count = rdataset->slab.iter_count;
  if (count == 0) {
    rdataset->slab.iter_pos = NULL;
    return ISC_R_NOMORE;
  }
  rdataset->slab.iter_count = count - 1;

  /*
   * Skip forward one record (length + 4) or one offset (4).
   */
  unsigned char *raw = rdataset->slab.iter_pos;
  uint16_t length = peek_uint16(raw);
  raw += length;
  rdataset->slab.iter_pos = raw + DNS_RDATASET_LENGTH;

  return ISC_R_SUCCESS;
}

static void
rdataset_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata) {
  unsigned char *raw = NULL;
  unsigned int length;
  isc_region_t r;
  unsigned int flags = 0;

  raw = rdataset->slab.iter_pos;
  REQUIRE(raw != NULL);

  /*
   * Find the start of the record if not already in iter_pos
   * then skip the length and order fields.
   */
  length = peek_uint16(raw);

  raw += DNS_RDATASET_LENGTH;

  if (rdataset->type == dns_rdatatype_rrsig) {
    if (*raw & DNS_RDATASLAB_OFFLINE) {
      flags |= DNS_RDATA_OFFLINE;
    }
    length--;
    raw++;
  }
  r.length = length;
  r.base = raw;
  dns_rdata_fromregion(rdata, rdataset->rdclass, rdataset->type, &r);
  rdata->flags |= flags;
}

static void
rdataset_clone(dns_rdataset_t *source, dns_rdataset_t *target DNS__DB_FLARG) {
  dns_db_t *db = source->slab.db;
  dns_dbnode_t *node = source->slab.node;
  dns_dbnode_t *cloned_node = NULL;

  dns__db_attachnode(db, node, &cloned_node DNS__DB_FLARG_PASS);
  INSIST(!ISC_LINK_LINKED(target, link));
  *target = *source;
  ISC_LINK_INIT(target, link);

  target->slab.iter_pos = NULL;
  target->slab.iter_count = 0;
}

static unsigned int
rdataset_count(dns_rdataset_t *rdataset) {
  unsigned char *raw = NULL;
  unsigned int count;

  raw = rdataset->slab.raw;
  count = get_uint16(raw);

  return count;
}

static isc_result_t
rdataset_getnoqname(dns_rdataset_t *rdataset, dns_name_t *name,
        dns_rdataset_t *nsec,
        dns_rdataset_t *nsecsig DNS__DB_FLARG) {
  dns_db_t *db = rdataset->slab.db;
  dns_dbnode_t *node = rdataset->slab.node;
  const dns_slabheader_proof_t *noqname = rdataset->slab.noqname;

  /*
   * The _KEEPCASE attribute is set to prevent setownercase and
   * getownercase methods from affecting the case of NSEC/NSEC3
   * owner names.
   */
  dns__db_attachnode(db, node,
         &(dns_dbnode_t *){ NULL } DNS__DB_FLARG_PASS);
  *nsec = (dns_rdataset_t){
    .methods = &dns_rdataslab_rdatasetmethods,
    .rdclass = db->rdclass,
    .type = noqname->type,
    .ttl = rdataset->ttl,
    .trust = rdataset->trust,
    .slab.db = db,
    .slab.node = node,
    .slab.raw = noqname->neg,
    .link = nsec->link,
    .count = nsec->count,
    .attributes = nsec->attributes,
    .magic = nsec->magic,
  };
  nsec->attributes.keepcase = true;

  dns__db_attachnode(db, node,
         &(dns_dbnode_t *){ NULL } DNS__DB_FLARG_PASS);
  *nsecsig = (dns_rdataset_t){
    .methods = &dns_rdataslab_rdatasetmethods,
    .rdclass = db->rdclass,
    .type = dns_rdatatype_rrsig,
    .covers = noqname->type,
    .ttl = rdataset->ttl,
    .trust = rdataset->trust,
    .slab.db = db,
    .slab.node = node,
    .slab.raw = noqname->negsig,
    .link = nsecsig->link,
    .count = nsecsig->count,
    .attributes = nsecsig->attributes,
    .magic = nsecsig->magic,
  };
  nsecsig->attributes.keepcase = true;

  dns_name_clone(&noqname->name, name);

  return ISC_R_SUCCESS;
}

static isc_result_t
rdataset_getclosest(dns_rdataset_t *rdataset, dns_name_t *name,
        dns_rdataset_t *nsec,
        dns_rdataset_t *nsecsig DNS__DB_FLARG) {
  dns_db_t *db = rdataset->slab.db;
  dns_dbnode_t *node = rdataset->slab.node;
  const dns_slabheader_proof_t *closest = rdataset->slab.closest;

  /*
   * As mentioned above, rdataset->slab.raw usually refers the data
   * following an dns_slabheader, but in this case it points to a bare
   * rdataslab belonging to the dns_slabheader's `closest` field.
   */
  dns__db_attachnode(db, node,
         &(dns_dbnode_t *){ NULL } DNS__DB_FLARG_PASS);
  *nsec = (dns_rdataset_t){
    .methods = &dns_rdataslab_rdatasetmethods,
    .rdclass = db->rdclass,
    .type = closest->type,
    .ttl = rdataset->ttl,
    .trust = rdataset->trust,
    .slab.db = db,
    .slab.node = node,
    .slab.raw = closest->neg,
    .link = nsec->link,
    .count = nsec->count,
    .attributes = nsec->attributes,
    .magic = nsec->magic,
  };
  nsec->attributes.keepcase = true;

  dns__db_attachnode(db, node,
         &(dns_dbnode_t *){ NULL } DNS__DB_FLARG_PASS);
  *nsecsig = (dns_rdataset_t){
    .methods = &dns_rdataslab_rdatasetmethods,
    .rdclass = db->rdclass,
    .type = dns_rdatatype_rrsig,
    .covers = closest->type,
    .ttl = rdataset->ttl,
    .trust = rdataset->trust,
    .slab.db = db,
    .slab.node = node,
    .slab.raw = closest->negsig,
    .link = nsecsig->link,
    .count = nsecsig->count,
    .attributes = nsecsig->attributes,
    .magic = nsecsig->magic,
  };
  nsecsig->attributes.keepcase = true;

  dns_name_clone(&closest->name, name);

  return ISC_R_SUCCESS;
}

static void
rdataset_settrust(dns_rdataset_t *rdataset, dns_trust_t trust) {
  dns_slabheader_t *header = dns_rdataset_getheader(rdataset);

  dns_db_locknode(header->db, header->node, isc_rwlocktype_write);
  header->trust = rdataset->trust = trust;
  dns_db_unlocknode(header->db, header->node, isc_rwlocktype_write);
}

static void
rdataset_expire(dns_rdataset_t *rdataset DNS__DB_FLARG) {
  dns_slabheader_t *header = dns_rdataset_getheader(rdataset);

  dns_db_expiredata(header->db, header->node, header);
}

static void
rdataset_clearprefetch(dns_rdataset_t *rdataset) {
  dns_slabheader_t *header = dns_rdataset_getheader(rdataset);

  dns_db_locknode(header->db, header->node, isc_rwlocktype_write);
  DNS_SLABHEADER_CLRATTR(header, DNS_SLABHEADERATTR_PREFETCH);
  dns_db_unlocknode(header->db, header->node, isc_rwlocktype_write);
}

static void
rdataset_setownercase(dns_rdataset_t *rdataset, const dns_name_t *name) {
  dns_slabheader_t *header = dns_rdataset_getheader(rdataset);

  DNS_SLABHEADER_CLRATTR(header, DNS_SLABHEADERATTR_CASEFULLYLOWER);

  dns_db_locknode(header->db, header->node, isc_rwlocktype_write);
  dns_slabheader_setownercase(header, name);
  dns_db_unlocknode(header->db, header->node, isc_rwlocktype_write);
}

static void
rdataset_getownercase(const dns_rdataset_t *rdataset, dns_name_t *name) {
  dns_slabheader_t *header = dns_rdataset_getheader(rdataset);
  uint8_t mask = (1 << 7);
  uint8_t bits = 0;

  if (CASEFULLYLOWER(header)) {
    isc_ascii_lowercopy(name->ndata, name->ndata, name->length);
    return;
  }

  dns_db_locknode(header->db, header->node, isc_rwlocktype_read);
  if (CASESET(header)) {
    uint8_t *nd = name->ndata;
    for (size_t i = 0; i < name->length; i++) {
      if (mask == (1 << 7)) {
        bits = header->upper[i / 8];
        mask = 1;
      } else {
        mask <<= 1;
      }
      nd[i] = (bits & mask) ? isc_ascii_toupper(nd[i])
                : isc_ascii_tolower(nd[i]);
    }
  }
  dns_db_unlocknode(header->db, header->node, isc_rwlocktype_read);
}

static dns_slabheader_t *
rdataset_getheader(const dns_rdataset_t *rdataset) {
  dns_slabheader_t *header = (dns_slabheader_t *)rdataset->slab.raw;
  return header - 1;
}

static bool
rdataset_equals(const dns_rdataset_t *rdataset1,
    const dns_rdataset_t *rdataset2) {
  if (rdataset1->rdclass != rdataset2->rdclass ||
      rdataset1->type != rdataset2->type)
  {
    return false;
  }

  dns_slabheader_t *header1 = (dns_slabheader_t *)rdataset1->slab.raw - 1;
  dns_slabheader_t *header2 = (dns_slabheader_t *)rdataset2->slab.raw - 1;

  return dns_rdataslab_equalx(header1, header2, rdataset1->rdclass,
            rdataset2->type);
}

Coverage Report

Created: 2025-08-03 06:33