/src/bind9/lib/dns/rdatavec.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.
 */

/*! \file */

#include <ctype.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdlib.h>

#include <isc/ascii.h>
#include <isc/atomic.h>
#include <isc/mem.h>
#include <isc/refcount.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/rdatavec.h>
#include <dns/stats.h>

#include "rdatavec_p.h"

/*
 * The memory structure of an rdatavec is as follows:
 *
 *  header    (dns_vecheader_t)
 *  record count  (2 bytes, big endian)
 *  data records
 *    data length (2 bytes, big endian)
 *    meta data (1 byte for RRSIG, 0 bytes for all other types)
 *    data    (data length bytes)
 *
 * A "bare" rdatavec is everything after the header. The first two bytes
 * contain the count of rdata records in the rdatavec. For records with
 * the DNS_VECHEADERATTR_NONEXISTENT attribute, the record count is omitted
 * entirely.
 *
 * After the count, the rdata records are stored sequentially in memory.
 * Each record consists of a length field, optional metadata, and the actual
 * rdata bytes.
 *
 * The rdata format depends on the RR type and is defined by the type-specific
 * *_fromwire and *_towire functions (e.g., lib/dns/rdata/in_1/a_1.c for A
 * records). The data is typically stored in wire format.
 *
 * When a vec is created, data records are sorted into DNSSEC canonical order.
 */

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(const dns_rdataset_t *source,
         dns_rdataset_t *target DNS__DB_FLARG);
static unsigned int
rdataset_count(dns_rdataset_t *rdataset);
static void
rdataset_settrust(dns_rdataset_t *rdataset, dns_trust_t trust);
static void
rdataset_getownercase(const dns_rdataset_t *rdataset, dns_name_t *name);

dns_rdatasetmethods_t dns_rdatavec_rdatasetmethods = {
  .disassociate = rdataset_disassociate,
  .first = rdataset_first,
  .next = rdataset_next,
  .current = rdataset_current,
  .clone = rdataset_clone,
  .count = rdataset_count,
  .settrust = rdataset_settrust,
  .expire = NULL,
  .clearprefetch = NULL,
  .getownercase = rdataset_getownercase,
};

/*% 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 size_t
header_size(const dns_vecheader_t *header) {
  UNUSED(header);
  return sizeof(dns_vecheader_t);
}

static unsigned char *
rdatavec_raw(dns_vecheader_t *header) {
  unsigned char *as_char_star = (unsigned char *)header;
  unsigned char *raw = as_char_star + header_size(header);

  return raw;
}

static unsigned char *
rdatavec_data(dns_vecheader_t *header) {
  return rdatavec_raw(header) + 2;
}

static unsigned int
rdatavec_count(dns_vecheader_t *header) {
  unsigned char *raw = rdatavec_raw(header);
  unsigned int count = get_uint16(raw);

  return count;
}

static unsigned char *
newvec(dns_rdataset_t *rdataset, isc_mem_t *mctx, isc_region_t *region,
       size_t size) {
  dns_vecheader_t *header = isc_mem_get(mctx, size);

  *header = (dns_vecheader_t){
    .next_header = ISC_SLINK_INITIALIZER,
    .trust = rdataset->trust,
    .ttl = rdataset->ttl,
    .references = ISC_REFCOUNT_INITIALIZER(1),
    .mctx = isc_mem_ref(mctx),
  };

  region->base = (unsigned char *)header;
  region->length = size;

  return (unsigned char *)header + sizeof(*header);
}

static isc_result_t
makevec(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_vecheader_t);
  uint32_t 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 vec, we don't need
   * to do anything special, just copy the whole vec to a
   * new buffer.
   */
  if (rdataset->methods == &dns_rdatavec_rdatasetmethods) {
    dns_vecheader_t *header = dns_vecheader_getheader(rdataset);
    buflen = dns_rdatavec_size(header);

    rawbuf = newvec(rdataset, mctx, region, buflen);

    INSIST(headerlen <= buflen);
    memmove(rawbuf, (unsigned char *)header + headerlen,
      buflen - headerlen);
    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 = newvec(rdataset, mctx, region, buflen);
    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(!ckd_mul(&rdatasize, nalloc, sizeof(rdata[0])));
  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 2 bytes for the length of each rdata, plus 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++;
      }
      if (buflen - headerlen - 2 > DNS_RDATA_MAXLENGTH) {
        result = ISC_R_NOSPACE;
        goto free_rdatas;
      }
    }
  }

  /*
   * 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++;
  }
  if (buflen - headerlen - 2 > DNS_RDATA_MAXLENGTH) {
    result = ISC_R_NOSPACE;
    goto free_rdatas;
  }

  /*
   * 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 = newvec(rdataset, mctx, region, buflen);
  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_RDATAVEC_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_rdatavec_fromrdataset(dns_rdataset_t *rdataset, isc_mem_t *mctx,
        isc_region_t *region, uint32_t maxrrperset) {
  isc_result_t result;

  if (rdataset->type == dns_rdatatype_none &&
      rdataset->covers == dns_rdatatype_none)
  {
    return DNS_R_DISALLOWED;
  }

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

    INSIST(!rdataset->attributes.negative);
    INSIST(rdataset->type != dns_rdatatype_none);
    INSIST(dns_rdatatype_issig(rdataset->type) ||
           rdataset->covers == dns_rdatatype_none);

    /*
     * Reset the vecheader content, but keep the refcount and mctx.
     */
    *new = (dns_vecheader_t){
      .next_header = ISC_SLINK_INITIALIZER,
      .typepair = DNS_TYPEPAIR_VALUE(rdataset->type,
                   rdataset->covers),
      .trust = rdataset->trust,
      .ttl = rdataset->ttl,
      .references = atomic_load_acquire(&new->references),
      .mctx = new->mctx,
    };
  }

  return result;
}

unsigned int
dns_rdatavec_size(dns_vecheader_t *header) {
  REQUIRE(header != NULL);

  unsigned char *vec = rdatavec_raw(header);
  INSIST(vec != NULL);

  unsigned char *current = rdatavec_data(header);
  uint16_t count = rdatavec_count(header);

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

  return (unsigned int)(current - vec) + header_size(header);
}

unsigned int
dns_rdatavec_count(dns_vecheader_t *header) {
  REQUIRE(header != NULL);

  return rdatavec_count(header);
}

/*
 * Make the dns_rdata_t 'rdata' refer to the vec item
 * beginning at '*current' (which is part of a vec of type
 * 'type' and class 'rdclass') and advance '*current' to
 * point to the next item in the vec.
 */
static void
rdata_from_vecitem(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_RDATAVEC_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_vecitem(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 vecinfo {
  unsigned char *pos;
  dns_rdata_t rdata;
  bool dup;
} vecinfo_t;

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

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

  ocurrent = rdatavec_data(oheader);
  ocount = rdatavec_count(oheader);

  ncurrent = rdatavec_data(nheader);
  ncount = rdatavec_count(nheader);

  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 = header_size(oheader) + 2;

  /*
   * Allocate both info arrays up front so the cleanup path is
   * always safe to call regardless of where we exit.
   */
  oinfo = isc_mem_cget(mctx, ocount, sizeof(struct vecinfo));
  ninfo = isc_mem_cget(mctx, ncount, sizeof(struct vecinfo));

  /*
   * Gather the rdatas in the old vec and add their lengths to
   * the larget length.
   */
  for (size_t i = 0; i < ocount; i++) {
    oinfo[i].pos = ocurrent;
    dns_rdata_init(&oinfo[i].rdata);
    rdata_from_vecitem(&ocurrent, rdclass, type, &oinfo[i].rdata);
    tlength += (uint32_t)(ocurrent - oinfo[i].pos);
    if (tlength - header_size(oheader) - 2 > DNS_RDATA_MAXLENGTH) {
      CLEANUP(ISC_R_NOSPACE);
    }
  }

  /*
   * Then add the length of rdatas in the new vec that aren't
   * duplicated in the old vec.
   */
  for (size_t i = 0; i < ncount; i++) {
    ninfo[i].pos = ncurrent;
    dns_rdata_init(&ninfo[i].rdata);
    rdata_from_vecitem(&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 += (uint32_t)(ncurrent - ninfo[i].pos);
    if (tlength - header_size(oheader) - 2 > DNS_RDATA_MAXLENGTH) {
      CLEANUP(ISC_R_NOSPACE);
    }
    tcount++;
  }

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

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

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

  /* Resposition ncurrent at the first item. */
  ncurrent = rdatavec_data(nheader);

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

  if (tcount > 0xffff) {
    CLEANUP(ISC_R_NOSPACE);
  }

  /*
   * Allocate the target buffer and initialize the header.
   * Preserve the case of the old header, but the rest from the
   * new header.
   */
  unsigned char *tstart = isc_mem_get(mctx, tlength);
  dns_vecheader_t *as_header = (dns_vecheader_t *)tstart;
  uint16_t attrs = DNS_VECHEADER_GETATTR(
    oheader,
    DNS_VECHEADERATTR_CASESET | DNS_VECHEADERATTR_CASEFULLYLOWER);
  if (RESIGN(nheader)) {
    attrs |= DNS_VECHEADERATTR_RESIGN;
  }
  *as_header = (dns_vecheader_t){
    .typepair = nheader->typepair,
    .mctx = isc_mem_ref(mctx),
    .serial = nheader->serial,
    .ttl = nheader->ttl,
    .resign = nheader->resign,
    .next_header = ISC_SLINK_INITIALIZER,
  };
  isc_refcount_init(&as_header->references, 1);
  atomic_init(&as_header->attributes, attrs);
  atomic_init(&as_header->trust, atomic_load_acquire(&nheader->trust));
  memmove(as_header->upper, oheader->upper, sizeof(oheader->upper));

  tcurrent = tstart + header_size(nheader);

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

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

    /* Skip to the next non-duplicate in the new vec. */
    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_vecitem(&tcurrent, type, &oinfo[o].rdata);
      if (++o < ocount) {
        /* Skip to the next rdata in the old vec */
        continue;
      }
    } else {
      rdata_to_vecitem(&tcurrent, type, &ninfo[n++].rdata);
    }
  }

  INSIST(tcurrent == tstart + tlength);

  *theaderp = (dns_vecheader_t *)tstart;

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

  return result;
}

isc_result_t
dns_rdatavec_subtract(dns_vecheader_t *oheader, dns_vecheader_t *sheader,
          isc_mem_t *mctx, dns_rdataclass_t rdclass,
          dns_rdatatype_t type, unsigned int flags,
          dns_vecheader_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;
  uint32_t tlength;
  unsigned int tcount = 0, rcount = 0;
  vecinfo_t *oinfo = NULL, *sinfo = NULL;

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

  ocurrent = rdatavec_data(oheader);
  ocount = rdatavec_count(oheader);

  scurrent = rdatavec_data(sheader);
  scount = rdatavec_count(sheader);

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

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

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

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

    oinfo[i].pos = ocurrent;
    dns_rdata_init(&oinfo[i].rdata);
    rdata_from_vecitem(&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 vec to be subtracted,
       * so copy it to the target.  Add its length to
       * tlength and increment tcount.
       */
      tlength += (uint32_t)(ocurrent - oinfo[i].pos);
      if (tlength - header_size(oheader) - 2 >
          DNS_RDATA_MAXLENGTH)
      {
        CLEANUP(ISC_R_NOSPACE);
      }
      tcount++;
    }
  }

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

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

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

  /*
   * Allocate the target buffer and copy the old vec's header.
   */
  tstart = isc_mem_get(mctx, tlength);
  dns_vecheader_t *as_header = (dns_vecheader_t *)tstart;
  uint16_t attrs = RESIGN(oheader) ? DNS_VECHEADERATTR_RESIGN : 0;
  *as_header = (dns_vecheader_t){
    .typepair = oheader->typepair,
    .mctx = isc_mem_ref(mctx),
    .serial = oheader->serial,
    .ttl = oheader->ttl,
    .resign = oheader->resign,
    .next_header = ISC_SLINK_INITIALIZER,
  };
  isc_refcount_init(&as_header->references, 1);
  atomic_init(&as_header->attributes, attrs);
  atomic_init(&as_header->trust, atomic_load_acquire(&oheader->trust));
  memmove(as_header->upper, oheader->upper, sizeof(oheader->upper));

  tcurrent = tstart + header_size(oheader);

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

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

  INSIST(tcurrent == tstart + tlength);

  *theaderp = (dns_vecheader_t *)tstart;

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

  return result;
}

void
dns_vecheader_setownercase(dns_vecheader_t *header, const dns_name_t *name) {
  REQUIRE(!CASESET(header));

  bool casefullylower = true;

  /*
   * 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));
  for (size_t i = 0; i < name->length; i++) {
    if (isupper(name->ndata[i])) {
      header->upper[i / 8] |= 1 << (i % 8);
      casefullylower = false;
    }
  }
  if (casefullylower) {
    DNS_VECHEADER_SETATTR(header, DNS_VECHEADERATTR_CASEFULLYLOWER);
  }
  DNS_VECHEADER_SETATTR(header, DNS_VECHEADERATTR_CASESET);
}

dns_vecheader_t *
dns_vecheader_new(isc_mem_t *mctx) {
  dns_vecheader_t *h = NULL;

  h = isc_mem_get(mctx, sizeof(*h));
  *h = (dns_vecheader_t){
    .references = ISC_REFCOUNT_INITIALIZER(1),
    .mctx = isc_mem_ref(mctx),
  };
  return h;
}

/* Iterators for already bound rdatavec */

isc_result_t
vecheader_first(rdatavec_iter_t *iter, dns_vecheader_t *header,
    dns_rdataclass_t rdclass) {
  unsigned char *raw = rdatavec_data(header);
  uint16_t count = rdatavec_count(header);
  if (count == 0) {
    iter->iter_pos = NULL;
    iter->iter_count = 0;
    return ISC_R_NOMORE;
  }

  /*
   * iter.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.
   */
  iter->iter_pos = raw;
  iter->iter_count = count - 1;
  iter->iter_rdclass = rdclass;
  iter->iter_type = DNS_TYPEPAIR_TYPE(header->typepair);

  return ISC_R_SUCCESS;
}

isc_result_t
vecheader_next(rdatavec_iter_t *iter) {
  uint16_t count = iter->iter_count;
  if (count == 0) {
    iter->iter_pos = NULL;
    return ISC_R_NOMORE;
  }
  iter->iter_count = count - 1;

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

  return ISC_R_SUCCESS;
}

void
vecheader_current(rdatavec_iter_t *iter, dns_rdata_t *rdata) {
  unsigned char *raw = NULL;
  unsigned int length;
  isc_region_t r;
  unsigned int flags = 0;

  raw = iter->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 = get_uint16(raw);

  if (iter->iter_type == dns_rdatatype_rrsig) {
    if (*raw & DNS_RDATAVEC_OFFLINE) {
      flags |= DNS_RDATA_OFFLINE;
    }
    length--;
    raw++;
  }
  r.length = length;
  r.base = raw;
  dns_rdata_fromregion(rdata, iter->iter_rdclass, iter->iter_type, &r);
  rdata->flags |= flags;
}

/* Fixed RRSet helper macros */

static void
rdataset_disassociate(dns_rdataset_t *rdataset DNS__DB_FLARG) {
  dns_vecheader_unref(rdataset->vec.header);
}

static isc_result_t
rdataset_first(dns_rdataset_t *rdataset) {
  return vecheader_first(&rdataset->vec.iter, rdataset->vec.header,
             rdataset->rdclass);
}

static isc_result_t
rdataset_next(dns_rdataset_t *rdataset) {
  return vecheader_next(&rdataset->vec.iter);
}

static void
rdataset_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata) {
  vecheader_current(&rdataset->vec.iter, rdata);
}

static void
rdataset_clone(const dns_rdataset_t *source,
         dns_rdataset_t *target DNS__DB_FLARG) {
  INSIST(!ISC_LINK_LINKED(target, link));
  *target = *source;
  ISC_LINK_INIT(target, link);

  target->vec.iter.iter_pos = NULL;
  target->vec.iter.iter_count = 0;

  dns_vecheader_ref(target->vec.header);
}

static unsigned int
rdataset_count(dns_rdataset_t *rdataset) {
  return rdatavec_count(rdataset->vec.header);
}

static void
rdataset_settrust(dns_rdataset_t *rdataset, dns_trust_t trust) {
  dns_vecheader_t *header = dns_vecheader_getheader(rdataset);

  rdataset->trust = trust;
  atomic_store_release(&header->trust, trust);
}

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

  if (!CASESET(header)) {
    return;
  }

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

  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_vecheader_t *
dns_vecheader_getheader(const dns_rdataset_t *rdataset) {
  return rdataset->vec.header;
}

dns_vecheader_t *
dns_vecheader_moveheader(dns_rdataset_t *rdataset) {
  dns_vecheader_t *header = MOVE_OWNERSHIP(rdataset->vec.header);
  /*
   * We stole the header, it is safe to reset the rdataset.
   */
  dns_rdataset_init(rdataset);
  return header;
}

dns_vectop_t *
dns_vectop_new(isc_mem_t *mctx, dns_typepair_t typepair) {
  dns_vectop_t *top = isc_mem_get(mctx, sizeof(*top));
  *top = (dns_vectop_t){
    .next_type = ISC_SLINK_INITIALIZER,
    .headers = ISC_SLIST_INITIALIZER,
    .typepair = typepair,
  };

  return top;
}

void
dns_vectop_destroy(isc_mem_t *mctx, dns_vectop_t **topp) {
  REQUIRE(topp != NULL && *topp != NULL);
  dns_vectop_t *top = *topp;
  *topp = NULL;
  isc_mem_put(mctx, top, sizeof(*top));
}

static void
vecheader_destroy(dns_vecheader_t *header) {
  unsigned int size = EXISTS(header) ? dns_rdatavec_size(header)
             : sizeof(*header);

  isc_mem_putanddetach(&header->mctx, header, size);
}

/*
 * Reference counting implementation for dns_vecheader_t
 */
ISC_REFCOUNT_IMPL(dns_vecheader, vecheader_destroy);

Coverage Report

Created: 2026-09-14 06:46