/src/bind9/lib/dns/xfrin.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 <inttypes.h>
#include <stdbool.h>

#include <isc/async.h>
#include <isc/atomic.h>
#include <isc/log.h>
#include <isc/mem.h>
#include <isc/queue.h>
#include <isc/random.h>
#include <isc/result.h>
#include <isc/string.h>
#include <isc/util.h>
#include <isc/work.h>

#include <dns/callbacks.h>
#include <dns/catz.h>
#include <dns/db.h>
#include <dns/diff.h>
#include <dns/dispatch.h>
#include <dns/journal.h>
#include <dns/message.h>
#include <dns/peer.h>
#include <dns/rdataclass.h>
#include <dns/rdatalist.h>
#include <dns/rdataset.h>
#include <dns/result.h>
#include <dns/soa.h>
#include <dns/trace.h>
#include <dns/transport.h>
#include <dns/tsig.h>
#include <dns/unreachcache.h>
#include <dns/view.h>
#include <dns/xfrin.h>
#include <dns/zone.h>
#include <dns/zoneproperties.h>

#include <dst/dst.h>

#include "probes-dns.h"

/*
 * Incoming AXFR and IXFR.
 */

/*%
 * The states of the *XFR state machine.  We handle both IXFR and AXFR
 * with a single integrated state machine because they cannot be
 * distinguished immediately - an AXFR response to an IXFR request can
 * only be detected when the first two (2) response RRs have already
 * been received.
 */
typedef enum {
  XFRST_SOAQUERY,
  XFRST_GOTSOA,
  XFRST_ZONEXFRREQUEST,
  XFRST_FIRSTDATA,
  XFRST_IXFR_DELSOA,
  XFRST_IXFR_DEL,
  XFRST_IXFR_ADDSOA,
  XFRST_IXFR_ADD,
  XFRST_IXFR_END,
  XFRST_AXFR,
  XFRST_AXFR_END
} xfrin_state_t;

/*%
 * Incoming zone transfer context.
 */

typedef struct dns_ixfr {
  uint32_t diffs;
  uint32_t maxdiffs;
  uint32_t request_serial;
  uint32_t current_serial;
  dns_journal_t *journal;
} dns_ixfr_t;

struct dns_xfrin {
  unsigned int magic;
  isc_mem_t *mctx;
  dns_zone_t *zone;
  dns_view_t *view;

  isc_refcount_t references;

  atomic_bool shuttingdown;

  isc_result_t shutdown_result;

  dns_name_t name; /*%< Name of zone to transfer */
  dns_rdataclass_t rdclass;

  dns_messageid_t id;

  /*%
   * Requested transfer type (dns_rdatatype_axfr or
   * dns_rdatatype_ixfr).  The actual transfer type
   * may differ due to IXFR->AXFR fallback.
   */
  dns_rdatatype_t reqtype;

  isc_sockaddr_t primaryaddr;
  isc_sockaddr_t sourceaddr;

  dns_dispatch_t *disp;
  dns_dispentry_t *dispentry;

  /*% Buffer for IXFR/AXFR request message */
  isc_buffer_t qbuffer;
  unsigned char qbuffer_data[512];

  /*%
   * Whether the zone originally had a database attached at the time this
   * transfer context was created.  Used by xfrin_destroy() when making
   * logging decisions.
   */
  bool zone_had_db;

  dns_db_t *db;
  dns_dbversion_t *ver;
  dns_diff_t diff; /*%< Pending database changes */

  /* Diff queue */
  bool diff_running;
  isc_queue_t diff_queue;

  _Atomic xfrin_state_t state;
  uint32_t expireopt;
  bool edns, expireoptset, retry_axfr;
  atomic_bool is_ixfr;

  /*
   * Following variable were made atomic only for loading the values for
   * the statistics channel, thus all accesses can be **relaxed** because
   * all store and load operations that affect XFR are done on the same
   * thread and only the statistics channel thread could perform a load
   * operation from a different thread and it's ok to not be precise in
   * the statistics.
   */
  atomic_uint nmsg;      /*%< Number of messages recvd */
  atomic_uint nrecs;       /*%< Number of records recvd */
  atomic_uint_fast64_t nbytes; /*%< Number of bytes received */
  _Atomic(isc_time_t) start;   /*%< Start time of the transfer */
  atomic_uint_fast64_t rate_bytes_per_second;
  _Atomic(dns_transport_type_t) soa_transport_type;
  atomic_uint_fast32_t end_serial;

  unsigned int maxrecords; /*%< The maximum number of
          *   records set for the zone */
  uint64_t nbytes_saved;   /*%< For enforcing the minimum transfer rate */

  dns_tsigkey_t *tsigkey; /*%< Key used to create TSIG */
  isc_buffer_t *lasttsig; /*%< The last TSIG */

  dns_transport_t *transport;

  dns_xfrindone_t done;

  /*%
   * AXFR- and IXFR-specific data.  Only one is used at a time
   * according to the is_ixfr flag, so this could be a union,
   * but keeping them separate makes it a bit simpler to clean
   * things up when destroying the context.
   */
  dns_rdatacallbacks_t axfr;

  dns_ixfr_t ixfr;

  dns_rdata_t firstsoa;
  unsigned char *firstsoa_data;

  isc_tlsctx_cache_t *tlsctx_cache;

  isc_loop_t *loop;

  isc_timer_t *min_rate_timer;
  isc_timer_t *max_time_timer;
  isc_timer_t *max_idle_timer;

  char info[DNS_NAME_MAXTEXT + 32];
};

#define XFRIN_MAGIC    ISC_MAGIC('X', 'f', 'r', 'I')
#define VALID_XFRIN(x) ISC_MAGIC_VALID(x, XFRIN_MAGIC)

/**************************************************************************/
/*
 * Forward declarations.
 */

static void
xfrin_create(isc_mem_t *mctx, dns_zone_t *zone, dns_db_t *db, isc_loop_t *loop,
       dns_name_t *zonename, dns_rdataclass_t rdclass,
       dns_rdatatype_t reqtype, uint32_t ixfr_maxdiffs,
       const isc_sockaddr_t *primaryaddr,
       const isc_sockaddr_t *sourceaddr, dns_tsigkey_t *tsigkey,
       dns_transport_type_t soa_transport_type,
       dns_transport_t *transport, isc_tlsctx_cache_t *tlsctx_cache,
       dns_xfrin_t **xfrp);

static isc_result_t
axfr_init(dns_xfrin_t *xfr);
static isc_result_t
axfr_putdata(dns_xfrin_t *xfr, dns_diffop_t op, dns_name_t *name, dns_ttl_t ttl,
       dns_rdata_t *rdata);
static void
axfr_commit(dns_xfrin_t *xfr);
static isc_result_t
axfr_finalize(dns_xfrin_t *xfr);

static isc_result_t
ixfr_init(dns_xfrin_t *xfr);
static isc_result_t
ixfr_putdata(dns_xfrin_t *xfr, dns_diffop_t op, dns_name_t *name, dns_ttl_t ttl,
       dns_rdata_t *rdata);
static isc_result_t
ixfr_commit(dns_xfrin_t *xfr);

static isc_result_t
xfr_rr(dns_xfrin_t *xfr, dns_name_t *name, uint32_t ttl, dns_rdata_t *rdata);

static isc_result_t
xfrin_start(dns_xfrin_t *xfr);

static void
xfrin_connect_done(isc_result_t eresult, isc_region_t *region, void *arg);
static isc_result_t
xfrin_send_request(dns_xfrin_t *xfr);
static void
xfrin_send_done(isc_result_t eresult, isc_region_t *region, void *arg);
static void
xfrin_recv_done(isc_result_t result, isc_region_t *region, void *arg);

static void
xfrin_end(dns_xfrin_t *xfr, isc_result_t result);

static void
xfrin_destroy(dns_xfrin_t *xfr);

static void
xfrin_timedout(void *);
static void
xfrin_idledout(void *);
static void
xfrin_minratecheck(void *);
static void
xfrin_reset(dns_xfrin_t *xfr);
static void
xfrin_ixfrcleanup(dns_xfrin_t *xfr);
static void
xfrin_fail(dns_xfrin_t *xfr, isc_result_t result, const char *msg);
static isc_result_t
render(dns_message_t *msg, isc_mem_t *mctx, isc_buffer_t *buf);

static void
xfrin_log(dns_xfrin_t *xfr, int level, const char *fmt, ...)
  ISC_FORMAT_PRINTF(3, 4);

/**************************************************************************/
/*
 * AXFR handling
 */

static isc_result_t
axfr_init(dns_xfrin_t *xfr) {
  isc_result_t result;

  atomic_store(&xfr->is_ixfr, false);

  if (xfr->db != NULL) {
    dns_db_detach(&xfr->db);
  }

  CHECK(dns_zone_makedb(xfr->zone, &xfr->db));

  dns_zone_rpz_enable_db(xfr->zone, xfr->db);
  dns_zone_catz_enable_db(xfr->zone, xfr->db);

  dns_rdatacallbacks_init(&xfr->axfr);
  CHECK(dns_db_beginload(xfr->db, &xfr->axfr));
  result = ISC_R_SUCCESS;
cleanup:
  return result;
}

static isc_result_t
axfr_apply(void *arg);

static isc_result_t
axfr_putdata(dns_xfrin_t *xfr, dns_diffop_t op, dns_name_t *name, dns_ttl_t ttl,
       dns_rdata_t *rdata) {
  isc_result_t result;

  dns_difftuple_t *tuple = NULL;

  if (rdata->rdclass != xfr->rdclass) {
    return DNS_R_BADCLASS;
  }

  CHECK(dns_zone_checknames(xfr->zone, name, rdata));
  if (dns_diff_size(&xfr->diff) > 128) {
    CHECK(axfr_apply(xfr));
  }

  dns_difftuple_create(xfr->diff.mctx, op, name, ttl, rdata, &tuple);
  dns_diff_append(&xfr->diff, &tuple);

  result = ISC_R_SUCCESS;
cleanup:
  return result;
}

/*
 * Store a set of AXFR RRs in the database.
 */
static isc_result_t
axfr_apply(void *arg) {
  dns_xfrin_t *xfr = arg;
  REQUIRE(VALID_XFRIN(xfr));

  isc_result_t result = ISC_R_SUCCESS;
  uint64_t records;

  if (atomic_load(&xfr->shuttingdown)) {
    CLEANUP(ISC_R_SHUTTINGDOWN);
  }

  CHECK(dns_diff_load(&xfr->diff, &xfr->axfr));
  if (xfr->maxrecords != 0U) {
    result = dns_db_getsize(xfr->db, xfr->ver, &records, NULL);
    if (result == ISC_R_SUCCESS && records > xfr->maxrecords) {
      CLEANUP(DNS_R_TOOMANYRECORDS);
    }
  }

cleanup:
  dns_diff_clear(&xfr->diff);

  return result;
}

static void
axfr_apply_done(void *arg, isc_result_t result) {
  dns_xfrin_t *xfr = arg;

  REQUIRE(VALID_XFRIN(xfr));

  if (atomic_load(&xfr->shuttingdown)) {
    result = ISC_R_SHUTTINGDOWN;
  }

  if (result == ISC_R_SUCCESS) {
    CHECK(dns_db_endload(xfr->db, &xfr->axfr));
    if (dns_zone_gettype(xfr->zone) == dns_zone_mirror) {
      CHECK(dns_zone_verifydb(xfr->view, xfr->db, NULL));
    }
    CHECK(axfr_finalize(xfr));
  } else {
    (void)dns_db_endload(xfr->db, &xfr->axfr);
  }

cleanup:
  xfr->diff_running = false;

  if (result == ISC_R_SUCCESS) {
    if (atomic_load(&xfr->state) == XFRST_AXFR_END) {
      xfrin_end(xfr, result);
    }
  } else {
    xfrin_fail(xfr, result, "failed while processing responses");
  }

  dns_xfrin_detach(&xfr);
}

static void
axfr_commit(dns_xfrin_t *xfr) {
  REQUIRE(!xfr->diff_running);

  dns_xfrin_ref(xfr);
  xfr->diff_running = true;
  isc_work_enqueue(xfr->loop, ISC_WORKLANE_SLOW, axfr_apply,
       axfr_apply_done, xfr);
}

static isc_result_t
axfr_finalize(dns_xfrin_t *xfr) {
  isc_result_t result;

  LIBDNS_XFRIN_AXFR_FINALIZE_BEGIN(xfr, xfr->info);
  result = dns_zone_replacedb(xfr->zone, xfr->db, true);
  LIBDNS_XFRIN_AXFR_FINALIZE_END(xfr, xfr->info, result);

  return result;
}

/**************************************************************************/
/*
 * IXFR handling
 */

typedef struct ixfr_apply_data {
  dns_diff_t diff; /*%< Pending database changes */
  isc_queue_node_t queue_node;
} ixfr_apply_data_t;

static isc_result_t
ixfr_init(dns_xfrin_t *xfr) {
  isc_result_t result;
  char *journalfile = NULL;

  if (xfr->reqtype != dns_rdatatype_ixfr) {
    xfrin_log(xfr, ISC_LOG_NOTICE,
        "got incremental response to AXFR request");
    return DNS_R_FORMERR;
  }

  atomic_store(&xfr->is_ixfr, true);
  INSIST(xfr->db != NULL);

  journalfile = dns_zone_getjournal(xfr->zone);
  if (journalfile != NULL) {
    CHECK(dns_journal_open(xfr->mctx, journalfile,
               DNS_JOURNAL_CREATE, &xfr->ixfr.journal));
  }

  result = ISC_R_SUCCESS;
cleanup:
  return result;
}

static isc_result_t
ixfr_putdata(dns_xfrin_t *xfr, dns_diffop_t op, dns_name_t *name, dns_ttl_t ttl,
       dns_rdata_t *rdata) {
  isc_result_t result = ISC_R_SUCCESS;
  dns_difftuple_t *tuple = NULL;

  if (rdata->rdclass != xfr->rdclass) {
    return DNS_R_BADCLASS;
  }

  if (op == DNS_DIFFOP_ADD) {
    CHECK(dns_zone_checknames(xfr->zone, name, rdata));
  }

  dns_difftuple_create(xfr->diff.mctx, op, name, ttl, rdata, &tuple);
  dns_diff_append(&xfr->diff, &tuple);

  xfr->ixfr.diffs++;
cleanup:
  return result;
}

static isc_result_t
ixfr_begin_transaction(dns_ixfr_t *ixfr) {
  isc_result_t result = ISC_R_SUCCESS;

  if (ixfr->journal != NULL) {
    CHECK(dns_journal_begin_transaction(ixfr->journal));
  }
cleanup:
  return result;
}

static isc_result_t
ixfr_end_transaction(dns_ixfr_t *ixfr) {
  isc_result_t result = ISC_R_SUCCESS;
  /* XXX enter ready-to-commit state here */
  if (ixfr->journal != NULL) {
    CHECK(dns_journal_commit(ixfr->journal));
  }
cleanup:
  return result;
}

static isc_result_t
ixfr_apply_one(dns_xfrin_t *xfr, ixfr_apply_data_t *data) {
  isc_result_t result = ISC_R_SUCCESS;
  uint64_t records;

  dns_rdatacallbacks_t callbacks;
  dns_rdatacallbacks_init(&callbacks);

  CHECK(ixfr_begin_transaction(&xfr->ixfr));

  dns_db_beginupdate(xfr->db, xfr->ver, &callbacks);

  CHECK(dns_diff_apply_with_callbacks(&data->diff, &callbacks));
  if (xfr->maxrecords != 0U) {
    result = dns_db_getsize(xfr->db, xfr->ver, &records, NULL);
    if (result == ISC_R_SUCCESS && records > xfr->maxrecords) {
      CLEANUP(DNS_R_TOOMANYRECORDS);
    }
  }
  if (xfr->ixfr.journal != NULL) {
    CHECK(dns_journal_writediff(xfr->ixfr.journal, &data->diff));
  }
  /*
   * In the current implementation, we always commit the results, since
   * dns_zone_verifydb doesn't know how to access the in-progress
   * transaction.
   */
  dns_db_commitupdate(xfr->db, &callbacks);

  /*
   * At the moment, rdatacallbacks doesn't offer a way to inspect the
   * result of a transaction before committing it.
   *
   * So we need to commit *before* calling dns_zone_verifydb, and rely
   * on closeversion to actually do cleanup.
   */
  dns_db_commitupdate(xfr->db, &callbacks);

  if (dns_zone_gettype(xfr->zone) == dns_zone_mirror) {
    CHECK(dns_zone_verifydb(xfr->view, xfr->db, xfr->ver));
  }

  result = ixfr_end_transaction(&xfr->ixfr);

  return result;
cleanup:
  /*
   * For the reason stated above, dns_db_abortupdate must *commit* the
   * changes and rely on closeversion to clean them up.
   */
  dns_db_abortupdate(xfr->db, &callbacks);

  /* We need to end the transaction, but keep the previous error */
  (void)ixfr_end_transaction(&xfr->ixfr);

  return result;
}

static isc_result_t
ixfr_apply(void *arg) {
  dns_xfrin_t *xfr = arg;
  isc_result_t result = ISC_R_SUCCESS;

  REQUIRE(VALID_XFRIN(xfr));

  isc_queue_t diff_queue;

  /* Initialize local queue */
  isc_queue_init(&diff_queue);

  if (!isc_queue_splice(&diff_queue, &xfr->diff_queue)) {
    return ISC_R_SUCCESS;
  }

  ixfr_apply_data_t *data = NULL, *next = NULL;
  isc_queue_for_each_entry_safe(&diff_queue, data, next, queue_node) {
    if (atomic_load(&xfr->shuttingdown)) {
      result = ISC_R_SHUTTINGDOWN;
    }

    /* Apply only until first failure */
    if (result == ISC_R_SUCCESS) {
      /* This also checks for shuttingdown condition */
      result = ixfr_apply_one(xfr, data);
    }

    /* We need to clear and free all data chunks */
    dns_diff_clear(&data->diff);
    isc_mem_put(xfr->mctx, data, sizeof(*data));
  }

  return result;
}

static void
ixfr_apply_done(void *arg, isc_result_t result) {
  dns_xfrin_t *xfr = arg;
  REQUIRE(VALID_XFRIN(xfr));

  if (atomic_load(&xfr->shuttingdown)) {
    result = ISC_R_SHUTTINGDOWN;
  }

  CHECK(result);

  /* Reschedule */
  if (!xfr->retry_axfr && !isc_queue_empty(&xfr->diff_queue)) {
    isc_work_enqueue(xfr->loop, ISC_WORKLANE_SLOW, ixfr_apply,
         ixfr_apply_done, xfr);
    return;
  }

cleanup:
  xfr->diff_running = false;

  /*
   * Don't retry with AXFR (even if it was requested) because there was
   * an error or the transfer is shutting down. In case if it _was_ an
   * error, xfrin_fail() will return a special result code which will
   * still result in AXFR retry from the initiator of the transfer after
   * the failure has been is logged.
   */
  if (result != ISC_R_SUCCESS) {
    xfr->retry_axfr = false;
  }

  if (!xfr->retry_axfr && result == ISC_R_SUCCESS) {
    dns_db_closeversion(xfr->db, &xfr->ver, true);
    dns_zone_markdirty(xfr->zone);

    if (atomic_load(&xfr->state) == XFRST_IXFR_END) {
      xfrin_end(xfr, result);
    }
  } else {
    dns_db_closeversion(xfr->db, &xfr->ver, false);

    if (result != ISC_R_SUCCESS) {
      xfrin_fail(xfr, result,
           "failed while processing responses");
    }
  }

  if (xfr->retry_axfr) {
    xfr->reqtype = dns_rdatatype_soa;
    atomic_store(&xfr->state, XFRST_SOAQUERY);

    xfrin_reset(xfr);
    result = xfrin_start(xfr);
    if (result != ISC_R_SUCCESS) {
      xfrin_fail(xfr, result, "failed setting up socket");
    }
  }

  dns_xfrin_detach(&xfr);
}

/*
 * Apply a set of IXFR changes to the database.
 */
static isc_result_t
ixfr_commit(dns_xfrin_t *xfr) {
  isc_result_t result = ISC_R_SUCCESS;
  ixfr_apply_data_t *data = isc_mem_get(xfr->mctx, sizeof(*data));

  *data = (ixfr_apply_data_t){ 0 };
  isc_queue_node_init(&data->queue_node);

  if (xfr->ver == NULL) {
    CHECK(dns_db_newversion(xfr->db, &xfr->ver));
  }

  dns_diff_init(xfr->mctx, &data->diff);
  dns_diff_appendlist(&data->diff, &xfr->diff);

  isc_queue_enqueue(&xfr->diff_queue, &data->queue_node);

  if (!xfr->diff_running) {
    dns_xfrin_ref(xfr);
    xfr->diff_running = true;
    isc_work_enqueue(xfr->loop, ISC_WORKLANE_SLOW, ixfr_apply,
         ixfr_apply_done, xfr);
  }

cleanup:
  if (result != ISC_R_SUCCESS) {
    isc_mem_put(xfr->mctx, data, sizeof(*data));
  }
  return result;
}

/**************************************************************************/
/*
 * Common AXFR/IXFR protocol code
 */

/*
 * Handle a single incoming resource record according to the current
 * state.
 */
static isc_result_t
xfr_rr(dns_xfrin_t *xfr, dns_name_t *name, uint32_t ttl, dns_rdata_t *rdata) {
  isc_result_t result;
  uint_fast32_t end_serial;

  atomic_fetch_add_relaxed(&xfr->nrecs, 1);

  if (rdata->type == dns_rdatatype_none ||
      dns_rdatatype_ismeta(rdata->type))
  {
    char buf[64];
    dns_rdatatype_format(rdata->type, buf, sizeof(buf));
    xfrin_log(xfr, ISC_LOG_NOTICE,
        "Unexpected %s record in zone transfer", buf);
    CLEANUP(DNS_R_FORMERR);
  }

  /*
   * Immediately reject the entire transfer if the RR that is currently
   * being processed is an SOA record that is not placed at the zone
   * apex.
   */
  if (rdata->type == dns_rdatatype_soa &&
      !dns_name_equal(&xfr->name, name))
  {
    char namebuf[DNS_NAME_FORMATSIZE];
    dns_name_format(name, namebuf, sizeof(namebuf));
    xfrin_log(xfr, ISC_LOG_NOTICE, "SOA name mismatch: '%s'",
        namebuf);
    CLEANUP(DNS_R_NOTZONETOP);
  }

  /*
   * Immediately reject the entire transfer if the owner of the RR that is
   * currently being processed is out of the zone.
   */
  if (!dns_name_issubdomain(name, &xfr->name)) {
    char namebuf[DNS_NAME_FORMATSIZE];
    dns_name_format(name, namebuf, sizeof(namebuf));
    xfrin_log(xfr, ISC_LOG_NOTICE,
        "out-of-zone data received: '%s'", namebuf);
    CLEANUP(DNS_R_FORMERR);
  }

redo:
  switch (atomic_load(&xfr->state)) {
  case XFRST_SOAQUERY:
    if (rdata->type != dns_rdatatype_soa) {
      xfrin_log(xfr, ISC_LOG_NOTICE,
          "non-SOA response to SOA query");
      CLEANUP(DNS_R_FORMERR);
    }
    end_serial = dns_soa_getserial(rdata);
    atomic_store_relaxed(&xfr->end_serial, end_serial);
    if (!DNS_SERIAL_GT(end_serial, xfr->ixfr.request_serial) &&
        !dns_zone_isforced(xfr->zone))
    {
      xfrin_log(xfr, ISC_LOG_DEBUG(3),
          "requested serial %u, "
          "primary has %" PRIuFAST32 ", not updating",
          xfr->ixfr.request_serial, end_serial);
      CLEANUP(DNS_R_UPTODATE);
    }
    atomic_store(&xfr->state, XFRST_GOTSOA);
    break;

  case XFRST_GOTSOA:
    /*
     * Skip other records in the answer section.
     */
    break;

  case XFRST_ZONEXFRREQUEST:
    if (rdata->type != dns_rdatatype_soa) {
      xfrin_log(xfr, ISC_LOG_NOTICE,
          "first RR in zone transfer must be SOA");
      CLEANUP(DNS_R_FORMERR);
    }
    /*
     * Remember the serial number in the initial SOA.
     * We need it to recognize the end of an IXFR.
     */
    end_serial = dns_soa_getserial(rdata);
    atomic_store_relaxed(&xfr->end_serial, end_serial);
    if (xfr->reqtype == dns_rdatatype_ixfr &&
        !DNS_SERIAL_GT(end_serial, xfr->ixfr.request_serial) &&
        !dns_zone_isforced(xfr->zone))
    {
      /*
       * This must be the single SOA record that is
       * sent when the current version on the primary
       * is not newer than the version in the request.
       */
      xfrin_log(xfr, ISC_LOG_DEBUG(3),
          "requested serial %u, "
          "primary has %" PRIuFAST32 ", not updating",
          xfr->ixfr.request_serial, end_serial);
      CLEANUP(DNS_R_UPTODATE);
    }
    xfr->firstsoa = *rdata;
    if (xfr->firstsoa_data != NULL) {
      isc_mem_free(xfr->mctx, xfr->firstsoa_data);
    }
    xfr->firstsoa_data = isc_mem_allocate(xfr->mctx, rdata->length);
    memcpy(xfr->firstsoa_data, rdata->data, rdata->length);
    xfr->firstsoa.data = xfr->firstsoa_data;
    atomic_store(&xfr->state, XFRST_FIRSTDATA);
    break;

  case XFRST_FIRSTDATA:
    /*
     * If the transfer begins with one SOA record, it is an AXFR,
     * if it begins with two SOAs, it is an IXFR.
     */
    if (xfr->reqtype == dns_rdatatype_ixfr &&
        rdata->type == dns_rdatatype_soa &&
        xfr->ixfr.request_serial == dns_soa_getserial(rdata))
    {
      xfrin_log(xfr, ISC_LOG_DEBUG(3),
          "got incremental response");
      CHECK(ixfr_init(xfr));
      atomic_store(&xfr->state, XFRST_IXFR_DELSOA);
    } else {
      xfrin_log(xfr, ISC_LOG_DEBUG(3),
          "got nonincremental response");
      CHECK(axfr_init(xfr));
      atomic_store(&xfr->state, XFRST_AXFR);
    }
    goto redo;

  case XFRST_IXFR_DELSOA:
    INSIST(rdata->type == dns_rdatatype_soa);
    CHECK(ixfr_putdata(xfr, DNS_DIFFOP_DEL, name, ttl, rdata));
    atomic_store(&xfr->state, XFRST_IXFR_DEL);
    break;

  case XFRST_IXFR_DEL:
    if (rdata->type == dns_rdatatype_soa) {
      uint32_t soa_serial = dns_soa_getserial(rdata);
      atomic_store(&xfr->state, XFRST_IXFR_ADDSOA);
      xfr->ixfr.current_serial = soa_serial;
      goto redo;
    }
    CHECK(ixfr_putdata(xfr, DNS_DIFFOP_DEL, name, ttl, rdata));
    break;

  case XFRST_IXFR_ADDSOA:
    INSIST(rdata->type == dns_rdatatype_soa);
    CHECK(ixfr_putdata(xfr, DNS_DIFFOP_ADD, name, ttl, rdata));
    atomic_store(&xfr->state, XFRST_IXFR_ADD);
    break;

  case XFRST_IXFR_ADD:
    if (rdata->type == dns_rdatatype_soa) {
      uint32_t soa_serial = dns_soa_getserial(rdata);
      if (soa_serial == atomic_load_relaxed(&xfr->end_serial))
      {
        CHECK(ixfr_commit(xfr));
        atomic_store(&xfr->state, XFRST_IXFR_END);
        break;
      } else if (soa_serial != xfr->ixfr.current_serial) {
        xfrin_log(xfr, ISC_LOG_NOTICE,
            "IXFR out of sync: "
            "expected serial %u, got %u",
            xfr->ixfr.current_serial, soa_serial);
        CLEANUP(DNS_R_FORMERR);
      } else {
        CHECK(ixfr_commit(xfr));
        atomic_store(&xfr->state, XFRST_IXFR_DELSOA);
        goto redo;
      }
    }
    if (rdata->type == dns_rdatatype_ns &&
        dns_name_iswildcard(name))
    {
      CLEANUP(DNS_R_INVALIDNS);
    }
    CHECK(ixfr_putdata(xfr, DNS_DIFFOP_ADD, name, ttl, rdata));
    break;

  case XFRST_AXFR:
    /*
     * Old BINDs sent cross class A records for non IN classes.
     */
    if (rdata->type == dns_rdatatype_a &&
        rdata->rdclass != xfr->rdclass &&
        xfr->rdclass != dns_rdataclass_in)
    {
      break;
    }
    CHECK(axfr_putdata(xfr, DNS_DIFFOP_ADD, name, ttl, rdata));
    if (rdata->type == dns_rdatatype_soa) {
      /*
       * Use dns_rdata_compare instead of memcmp to
       * allow for case differences.
       */
      if (dns_rdata_compare(rdata, &xfr->firstsoa) != 0) {
        xfrin_log(xfr, ISC_LOG_NOTICE,
            "start and ending SOA records "
            "mismatch");
        CLEANUP(DNS_R_FORMERR);
      }
      axfr_commit(xfr);
      atomic_store(&xfr->state, XFRST_AXFR_END);
      break;
    }
    break;
  case XFRST_AXFR_END:
  case XFRST_IXFR_END:
    CLEANUP(DNS_R_EXTRADATA);
    break;
  default:
    UNREACHABLE();
  }
  result = ISC_R_SUCCESS;
cleanup:
  return result;
}

void
dns_xfrin_create(dns_zone_t *zone, dns_rdatatype_t xfrtype,
     uint32_t ixfr_maxdiffs, const isc_sockaddr_t *primaryaddr,
     const isc_sockaddr_t *sourceaddr, dns_tsigkey_t *tsigkey,
     dns_transport_type_t soa_transport_type,
     dns_transport_t *transport, isc_tlsctx_cache_t *tlsctx_cache,
     isc_mem_t *mctx, dns_xfrin_t **xfrp) {
  dns_name_t *zonename = dns_zone_getorigin(zone);
  dns_xfrin_t *xfr = NULL;
  dns_db_t *db = NULL;
  isc_loop_t *loop = NULL;

  REQUIRE(xfrp != NULL && *xfrp == NULL);
  REQUIRE(isc_sockaddr_getport(primaryaddr) != 0);
  REQUIRE(zone != NULL);
  REQUIRE(dns_zone_getview(zone) != NULL);

  loop = dns_zone_getloop(zone);

  (void)dns_zone_getdb(zone, &db);

  if (xfrtype == dns_rdatatype_soa || xfrtype == dns_rdatatype_ixfr) {
    REQUIRE(db != NULL);
  }

  xfrin_create(mctx, zone, db, loop, zonename, dns_zone_getclass(zone),
         xfrtype, ixfr_maxdiffs, primaryaddr, sourceaddr, tsigkey,
         soa_transport_type, transport, tlsctx_cache, &xfr);

  if (db != NULL) {
    xfr->zone_had_db = true;
    dns_db_detach(&db);
  }

  *xfrp = xfr;
}

isc_result_t
dns_xfrin_start(dns_xfrin_t *xfr, dns_xfrindone_t done) {
  isc_result_t result;

  REQUIRE(xfr != NULL);
  REQUIRE(xfr->zone != NULL);
  REQUIRE(done != NULL);

  xfr->done = done;

  result = xfrin_start(xfr);
  if (result != ISC_R_SUCCESS) {
    xfr->done = NULL;
    xfrin_fail(xfr, result, "zone transfer start failed");
  }

  return result;
}

static void
xfrin_timedout(void *xfr) {
  REQUIRE(VALID_XFRIN(xfr));

  xfrin_fail(xfr, ISC_R_TIMEDOUT, "maximum transfer time exceeded");
}

static void
xfrin_idledout(void *xfr) {
  REQUIRE(VALID_XFRIN(xfr));

  xfrin_fail(xfr, ISC_R_TIMEDOUT, "maximum idle time exceeded");
}

static void
xfrin_minratecheck(void *arg) {
  dns_xfrin_t *xfr = arg;

  REQUIRE(VALID_XFRIN(xfr));

  const uint64_t nbytes = atomic_load_relaxed(&xfr->nbytes);
  const uint64_t min = dns_zone_getminxfrratebytesin(xfr->zone);
  uint64_t rate = nbytes - xfr->nbytes_saved;

  if (rate < min) {
    isc_timer_stop(xfr->min_rate_timer);
    xfrin_fail(xfr, ISC_R_TIMEDOUT,
         "minimum transfer rate reached");
  } else {
    xfr->nbytes_saved = nbytes;

    /*
     * Calculate and store for the statistics channel the transfer
     * rate in bytes-per-second for the latest interval.
     */
    rate /= dns_zone_getminxfrratesecondsin(xfr->zone);
    atomic_store_relaxed(&xfr->rate_bytes_per_second, rate);
  }
}

isc_time_t
dns_xfrin_getstarttime(dns_xfrin_t *xfr) {
  REQUIRE(VALID_XFRIN(xfr));

  return atomic_load_relaxed(&xfr->start);
}

void
dns_xfrin_getstate(const dns_xfrin_t *xfr, const char **statestr,
       bool *is_first_data_received, bool *is_ixfr) {
  xfrin_state_t state;

  REQUIRE(VALID_XFRIN(xfr));
  REQUIRE(statestr != NULL && *statestr == NULL);
  REQUIRE(is_ixfr != NULL);

  state = atomic_load(&xfr->state);
  *statestr = "";
  *is_first_data_received = (state > XFRST_FIRSTDATA);
  *is_ixfr = atomic_load(&xfr->is_ixfr);

  switch (state) {
  case XFRST_SOAQUERY:
    *statestr = "SOA Query";
    break;
  case XFRST_GOTSOA:
    *statestr = "Got SOA";
    break;
  case XFRST_ZONEXFRREQUEST:
    *statestr = "Zone Transfer Request";
    break;
  case XFRST_FIRSTDATA:
    *statestr = "First Data";
    break;
  case XFRST_IXFR_DELSOA:
  case XFRST_IXFR_DEL:
  case XFRST_IXFR_ADDSOA:
  case XFRST_IXFR_ADD:
    *statestr = "Receiving IXFR Data";
    break;
  case XFRST_IXFR_END:
    *statestr = "Finalizing IXFR";
    break;
  case XFRST_AXFR:
    *statestr = "Receiving AXFR Data";
    break;
  case XFRST_AXFR_END:
    *statestr = "Finalizing AXFR";
    break;
  }
}

uint32_t
dns_xfrin_getendserial(dns_xfrin_t *xfr) {
  REQUIRE(VALID_XFRIN(xfr));

  return atomic_load_relaxed(&xfr->end_serial);
}

void
dns_xfrin_getstats(dns_xfrin_t *xfr, unsigned int *nmsgp, unsigned int *nrecsp,
       uint64_t *nbytesp, uint64_t *ratep) {
  REQUIRE(VALID_XFRIN(xfr));
  REQUIRE(nmsgp != NULL && nrecsp != NULL && nbytesp != NULL);

  uint64_t rate = atomic_load_relaxed(&xfr->rate_bytes_per_second);
  if (rate == 0) {
    /*
     * Likely the first 'min-transfer-rate-in <bytes> <minutes>'
     * minutes interval hasn't passed yet. Calculate the overall
     * average transfer rate instead.
     */
    isc_time_t now = isc_time_now();
    isc_time_t start = atomic_load_relaxed(&xfr->start);
    uint64_t sec = isc_time_microdiff(&now, &start) / US_PER_SEC;
    if (sec > 0) {
      rate = atomic_load_relaxed(&xfr->nbytes) / sec;
    }
  }

  SET_IF_NOT_NULL(nmsgp, atomic_load_relaxed(&xfr->nmsg));
  SET_IF_NOT_NULL(nrecsp, atomic_load_relaxed(&xfr->nrecs));
  SET_IF_NOT_NULL(nbytesp, atomic_load_relaxed(&xfr->nbytes));
  SET_IF_NOT_NULL(ratep, rate);
}

const isc_sockaddr_t *
dns_xfrin_getsourceaddr(const dns_xfrin_t *xfr) {
  REQUIRE(VALID_XFRIN(xfr));

  return &xfr->sourceaddr;
}

const isc_sockaddr_t *
dns_xfrin_getprimaryaddr(const dns_xfrin_t *xfr) {
  REQUIRE(VALID_XFRIN(xfr));

  return &xfr->primaryaddr;
}

dns_transport_type_t
dns_xfrin_gettransporttype(const dns_xfrin_t *xfr) {
  REQUIRE(VALID_XFRIN(xfr));

  if (xfr->transport != NULL) {
    return dns_transport_get_type(xfr->transport);
  }

  return DNS_TRANSPORT_TCP;
}

dns_transport_type_t
dns_xfrin_getsoatransporttype(dns_xfrin_t *xfr) {
  REQUIRE(VALID_XFRIN(xfr));

  return atomic_load_relaxed(&xfr->soa_transport_type);
}

const dns_name_t *
dns_xfrin_gettsigkeyname(const dns_xfrin_t *xfr) {
  REQUIRE(VALID_XFRIN(xfr));

  if (xfr->tsigkey == NULL || xfr->tsigkey->key == NULL) {
    return NULL;
  }

  return dst_key_name(xfr->tsigkey->key);
}

static void
xfrin_shutdown(void *arg) {
  dns_xfrin_t *xfr = arg;

  REQUIRE(VALID_XFRIN(xfr));

  xfrin_fail(xfr, ISC_R_SHUTTINGDOWN, "shut down");
  dns_xfrin_detach(&xfr);
}

void
dns_xfrin_shutdown(dns_xfrin_t *xfr) {
  REQUIRE(VALID_XFRIN(xfr));

  if (xfr->loop != isc_loop()) {
    dns_xfrin_ref(xfr);
    isc_async_run(xfr->loop, xfrin_shutdown, xfr);
  } else {
    xfrin_fail(xfr, ISC_R_SHUTTINGDOWN, "shut down");
  }
}

#if DNS_XFRIN_TRACE
ISC_REFCOUNT_TRACE_IMPL(dns_xfrin, xfrin_destroy);
#else
ISC_REFCOUNT_IMPL(dns_xfrin, xfrin_destroy);
#endif

static void
xfrin_cancelio(dns_xfrin_t *xfr) {
  if (xfr->dispentry != NULL) {
    dns_dispatch_done(&xfr->dispentry);
  }
  if (xfr->disp != NULL) {
    dns_dispatch_detach(&xfr->disp);
  }
}

static void
xfrin_reset(dns_xfrin_t *xfr) {
  REQUIRE(VALID_XFRIN(xfr));
  REQUIRE(!xfr->diff_running);

  xfrin_log(xfr, ISC_LOG_INFO, "resetting");

  xfr->retry_axfr = false;

  if (xfr->lasttsig != NULL) {
    isc_buffer_free(&xfr->lasttsig);
  }

  xfrin_ixfrcleanup(xfr);

  dns_diff_clear(&xfr->diff);
  xfr->ixfr.diffs = 0;

  if (xfr->ixfr.journal != NULL) {
    dns_journal_destroy(&xfr->ixfr.journal);
  }

  if (xfr->axfr.add_private != NULL) {
    (void)dns_db_endload(xfr->db, &xfr->axfr);
  }

  if (xfr->ver != NULL) {
    dns_db_closeversion(xfr->db, &xfr->ver, false);
  }
}

static void
xfrin_fail(dns_xfrin_t *xfr, isc_result_t result, const char *msg) {
  REQUIRE(VALID_XFRIN(xfr));

  dns_xfrin_ref(xfr);

  /* Make sure only the first xfrin_fail() trumps */
  if (atomic_compare_exchange_strong(&xfr->shuttingdown, &(bool){ false },
             true))
  {
    if (result != DNS_R_UPTODATE) {
      xfrin_log(xfr, ISC_LOG_ERROR, "%s: %s", msg,
          isc_result_totext(result));
      if (atomic_load(&xfr->is_ixfr) &&
          result != ISC_R_CANCELED &&
          result != ISC_R_SHUTTINGDOWN)
      {
        /*
         * Pass special result code to force AXFR retry
         */
        result = DNS_R_BADIXFR;
      }
    }

    xfrin_cancelio(xfr);

    xfrin_end(xfr, result);
  }

  dns_xfrin_detach(&xfr);
}

static void
xfrin_create(isc_mem_t *mctx, dns_zone_t *zone, dns_db_t *db, isc_loop_t *loop,
       dns_name_t *zonename, dns_rdataclass_t rdclass,
       dns_rdatatype_t reqtype, uint32_t ixfr_maxdiffs,
       const isc_sockaddr_t *primaryaddr,
       const isc_sockaddr_t *sourceaddr, dns_tsigkey_t *tsigkey,
       dns_transport_type_t soa_transport_type,
       dns_transport_t *transport, isc_tlsctx_cache_t *tlsctx_cache,
       dns_xfrin_t **xfrp) {
  dns_xfrin_t *xfr = NULL;

  xfr = isc_mem_get(mctx, sizeof(*xfr));
  *xfr = (dns_xfrin_t){
    .shutdown_result = ISC_R_UNSET,
    .rdclass = rdclass,
    .reqtype = reqtype,
    .ixfr.maxdiffs = ixfr_maxdiffs,
    .maxrecords = dns_zone_getmaxrecords(zone),
    .primaryaddr = *primaryaddr,
    .sourceaddr = *sourceaddr,
    .soa_transport_type = soa_transport_type,
    .firstsoa = DNS_RDATA_INIT,
    .edns = true,
    .references = 1,
    .magic = XFRIN_MAGIC,
  };

  isc_loop_attach(loop, &xfr->loop);
  isc_mem_attach(mctx, &xfr->mctx);
  dns_zone_iattach(zone, &xfr->zone);
  dns_view_weakattach(dns_zone_getview(zone), &xfr->view);
  dns_name_init(&xfr->name);

  isc_queue_init(&xfr->diff_queue);

  atomic_init(&xfr->is_ixfr, false);

  if (db != NULL) {
    dns_db_attach(db, &xfr->db);
  }

  dns_diff_init(xfr->mctx, &xfr->diff);

  if (reqtype == dns_rdatatype_soa) {
    atomic_init(&xfr->state, XFRST_SOAQUERY);
  } else {
    atomic_init(&xfr->state, XFRST_ZONEXFRREQUEST);
  }

  atomic_init(&xfr->start, isc_time_now());

  if (tsigkey != NULL) {
    dns_tsigkey_attach(tsigkey, &xfr->tsigkey);
  }

  if (transport != NULL) {
    dns_transport_attach(transport, &xfr->transport);
  }

  dns_name_dup(zonename, mctx, &xfr->name);

  INSIST(isc_sockaddr_pf(primaryaddr) == isc_sockaddr_pf(sourceaddr));
  isc_sockaddr_setport(&xfr->sourceaddr, 0);

  /*
   * Reserve 2 bytes for TCP length at the beginning of the buffer.
   */
  isc_buffer_init(&xfr->qbuffer, &xfr->qbuffer_data[2],
      sizeof(xfr->qbuffer_data) - 2);

  isc_tlsctx_cache_attach(tlsctx_cache, &xfr->tlsctx_cache);

  dns_zone_name(xfr->zone, xfr->info, sizeof(xfr->info));

  *xfrp = xfr;
}

static isc_result_t
xfrin_start(dns_xfrin_t *xfr) {
  isc_result_t result = ISC_R_FAILURE;
  isc_interval_t interval;
  uint32_t primaries_timeout;

  dns_xfrin_ref(xfr);

  /* If this is a retry, we need to cancel the previous dispentry */
  xfrin_cancelio(xfr);

  dns_dispatchmgr_t *dispmgr = dns_view_getdispatchmgr(xfr->view);
  if (dispmgr == NULL) {
    CLEANUP(ISC_R_SHUTTINGDOWN);
  }

  primaries_timeout = isc_nm_getprimariestimeout();
  result = dns_dispatch_createtcp(dispmgr, &xfr->sourceaddr,
          &xfr->primaryaddr, xfr->transport,
          DNS_DISPATCHTYPE_XFRIN, 0, &xfr->disp);
  dns_dispatchmgr_detach(&dispmgr);
  CHECK(result);

  LIBDNS_XFRIN_START(xfr, xfr->info);

  /*
   * If the transfer is started when the 'state' is XFRST_SOAQUERY, it
   * means the SOA query will be performed by xfrin. A transfer could also
   * be initiated starting from the XFRST_ZONEXFRREQUEST state, which
   * means that the SOA query was already performed by other means (e.g.
   * by zone.c:soa_query()), or that it's a transfer without a preceding
   * SOA request, and 'soa_transport_type' is already correctly
   * set by the creator of the xfrin.
   */
  if (atomic_load(&xfr->state) == XFRST_SOAQUERY) {
    /*
     * The "SOA before" mode is used, where the SOA request is
     * using the same transport as the XFR.
     */
    atomic_store_relaxed(&xfr->soa_transport_type,
             dns_xfrin_gettransporttype(xfr));
  }

  /*
   * The read timeout timer is disabled on the dispatch level because
   * the xfr module has its own timeouts.
   */
  const unsigned int read_timeout = 0;

  CHECK(dns_dispatch_add(xfr->disp, xfr->loop, 0, primaries_timeout,
             read_timeout, &xfr->primaryaddr, xfr->transport,
             xfr->tlsctx_cache, xfrin_connect_done,
             xfrin_send_done, xfrin_recv_done, xfr, &xfr->id,
             &xfr->dispentry));

  /* Set the maximum timer */
  if (xfr->max_time_timer == NULL) {
    isc_timer_create(dns_zone_getloop(xfr->zone), xfrin_timedout,
         xfr, &xfr->max_time_timer);
  }
  isc_interval_set(&interval, dns_zone_getmaxxfrin(xfr->zone), 0);
  isc_timer_start(xfr->max_time_timer, isc_timertype_once, &interval);

  /* Set the idle timer */
  if (xfr->max_idle_timer == NULL) {
    isc_timer_create(dns_zone_getloop(xfr->zone), xfrin_idledout,
         xfr, &xfr->max_idle_timer);
  }
  isc_interval_set(&interval, dns_zone_getidlein(xfr->zone), 0);
  isc_timer_start(xfr->max_idle_timer, isc_timertype_once, &interval);

  /* Set the minimum transfer rate checking timer */
  if (xfr->min_rate_timer == NULL) {
    isc_timer_create(dns_zone_getloop(xfr->zone),
         xfrin_minratecheck, xfr, &xfr->min_rate_timer);
  }
  isc_interval_set(&interval, dns_zone_getminxfrratesecondsin(xfr->zone),
       0);
  isc_timer_start(xfr->min_rate_timer, isc_timertype_ticker, &interval);

  /*
   * The connect has to be the last thing that is called before returning,
   * as it can end synchronously and destroy the xfr object.
   */
  CHECK(dns_dispatch_connect(xfr->dispentry));

  return ISC_R_SUCCESS;

cleanup:
  xfrin_cancelio(xfr);
  dns_xfrin_detach(&xfr);

  return result;
}

/* XXX the resolver could use this, too */

static isc_result_t
render(dns_message_t *msg, isc_mem_t *mctx, isc_buffer_t *buf) {
  dns_compress_t cctx;
  isc_result_t result;

  dns_compress_init(&cctx, mctx, 0);
  CHECK(dns_message_renderbegin(msg, &cctx, buf));
  CHECK(dns_message_rendersection(msg, DNS_SECTION_QUESTION, 0));
  CHECK(dns_message_rendersection(msg, DNS_SECTION_ANSWER, 0));
  CHECK(dns_message_rendersection(msg, DNS_SECTION_AUTHORITY, 0));
  CHECK(dns_message_rendersection(msg, DNS_SECTION_ADDITIONAL, 0));
  CHECK(dns_message_renderend(msg));
  result = ISC_R_SUCCESS;
cleanup:
  dns_compress_invalidate(&cctx);
  return result;
}

/*
 * A connection has been established.
 */
static void
xfrin_connect_done(isc_result_t eresult, isc_region_t *region ISC_ATTR_UNUSED,
       void *arg) {
  dns_xfrin_t *xfr = (dns_xfrin_t *)arg;
  char addrtext[ISC_SOCKADDR_FORMATSIZE];
  char signerbuf[DNS_NAME_FORMATSIZE];
  const char *signer = "", *sep = "";
  isc_result_t result;

  REQUIRE(VALID_XFRIN(xfr));

  result = atomic_load(&xfr->shuttingdown) ? ISC_R_SHUTTINGDOWN : eresult;

  LIBDNS_XFRIN_CONNECTED(xfr, xfr->info, result);

  if (result != ISC_R_SUCCESS) {
    xfrin_fail(xfr, result, "failed to connect");
    goto cleanup;
  }

  result = dns_dispatch_checkperm(xfr->disp);
  if (result != ISC_R_SUCCESS) {
    xfrin_fail(xfr, result, "connected but unable to transfer");
    goto cleanup;
  }

  if (dns_zone_getloop(xfr->zone) != NULL) {
    dns_view_t *view = dns_zone_getview(xfr->zone);
    dns_unreachcache_remove(view->unreachcache, &xfr->primaryaddr,
          &xfr->sourceaddr);
  }

  if (xfr->tsigkey != NULL && xfr->tsigkey->key != NULL) {
    dns_name_format(dst_key_name(xfr->tsigkey->key), signerbuf,
        sizeof(signerbuf));
    sep = " TSIG ";
    signer = signerbuf;
  }

  isc_sockaddr_format(&xfr->primaryaddr, addrtext, sizeof(addrtext));
  xfrin_log(xfr, ISC_LOG_INFO, "connected using %s%s%s", addrtext, sep,
      signer);

  result = xfrin_send_request(xfr);
  if (result != ISC_R_SUCCESS) {
    xfrin_fail(xfr, result, "connected but unable to send");
    goto detach;
  }

  return;

cleanup:
  switch (result) {
  case ISC_R_NETDOWN:
  case ISC_R_HOSTDOWN:
  case ISC_R_NETUNREACH:
  case ISC_R_HOSTUNREACH:
  case ISC_R_CONNREFUSED:
  case ISC_R_TIMEDOUT:
    /*
     * Add the server to unreachable primaries cache if
     * the server has a permanent networking error or
     * the connection attempt as timed out.
     */
    if (dns_zone_getloop(xfr->zone) != NULL) {
      dns_view_t *view = dns_zone_getview(xfr->zone);
      dns_unreachcache_add(view->unreachcache,
               &xfr->primaryaddr,
               &xfr->sourceaddr);
    }
    break;
  default:
    /* Retry sooner than in 10 minutes */
    break;
  }

detach:
  /*
   * If the connection was successful, then the reference now belongs to
   * the receive callback. Otherwise, detach it.
   */
  if (eresult != ISC_R_SUCCESS) {
    dns_xfrin_detach(&xfr);
  }
}

/*
 * Convert a tuple into a dns_name_t suitable for inserting
 * into the given dns_message_t.
 */
static void
tuple2msgname(dns_difftuple_t *tuple, dns_message_t *msg,
        dns_linkedname_t **target) {
  dns_rdata_t *rdata = NULL;
  dns_rdatalist_t *rdl = NULL;
  dns_rdataset_t *rds = NULL;
  dns_linkedname_t *name = NULL;

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

  dns_message_gettemprdata(msg, &rdata);
  dns_rdata_clone(&tuple->rdata, rdata);

  dns_message_gettemprdatalist(msg, &rdl);
  rdl->type = tuple->rdata.type;
  rdl->rdclass = tuple->rdata.rdclass;
  rdl->ttl = tuple->ttl;
  ISC_LIST_APPEND(rdl->rdata, rdata, link);

  dns_message_gettemprdataset(msg, &rds);
  dns_rdatalist_tordataset(rdl, rds);

  dns_message_gettempname(msg, &name);
  dns_name_clone(&tuple->name, dns_name(name));
  ISC_LIST_APPEND(name->list, rds, link);

  *target = name;
}

static const char *
request_type(dns_xfrin_t *xfr) {
  switch (xfr->reqtype) {
  case dns_rdatatype_soa:
    return "SOA";
  case dns_rdatatype_axfr:
    return "AXFR";
  case dns_rdatatype_ixfr:
    return "IXFR";
  default:
    ISC_UNREACHABLE();
  }
}

static isc_result_t
add_opt(dns_message_t *message, uint16_t udpsize, bool reqnsid,
  bool reqexpire) {
  dns_message_ednsinit(message, 0, udpsize, 0, 0);

  /* Set EDNS options if applicable. */
  if (reqnsid) {
    dns_ednsopt_t option = { .code = DNS_OPT_NSID };
    RETERR(dns_message_ednsaddopt(message, &option));
  }
  if (reqexpire) {
    dns_ednsopt_t option = { .code = DNS_OPT_EXPIRE };
    RETERR(dns_message_ednsaddopt(message, &option));
  }

  return dns_message_setopt(message);
}

/*
 * Build an *XFR request and send its length prefix.
 */
static isc_result_t
xfrin_send_request(dns_xfrin_t *xfr) {
  isc_result_t result;
  isc_region_t region;
  dns_rdataset_t *qrdataset = NULL;
  dns_message_t *msg = NULL;
  dns_difftuple_t *soatuple = NULL;
  dns_linkedname_t *qname = NULL;
  dns_dbversion_t *ver = NULL;
  dns_linkedname_t *msgsoaname = NULL;
  bool edns = xfr->edns;
  bool reqnsid = xfr->view->requestnsid;
  bool reqexpire = dns_zone_getrequestexpire(xfr->zone);
  uint16_t udpsize = dns_view_getudpsize(xfr->view);

  LIBDNS_XFRIN_RECV_SEND_REQUEST(xfr, xfr->info);

  /* Create the request message */
  dns_message_create(xfr->mctx, NULL, NULL, DNS_MESSAGE_INTENTRENDER,
         &msg);
  CHECK(dns_message_settsigkey(msg, xfr->tsigkey));

  /* Create a name for the question section. */
  dns_message_gettempname(msg, &qname);
  dns_name_clone(&xfr->name, dns_name(qname));

  /* Formulate the question and attach it to the question name. */
  dns_message_gettemprdataset(msg, &qrdataset);
  dns_rdataset_makequestion(qrdataset, xfr->rdclass, xfr->reqtype);
  ISC_LIST_APPEND(qname->list, qrdataset, link);
  qrdataset = NULL;

  dns_message_addname(msg, qname, DNS_SECTION_QUESTION);
  qname = NULL;

  if (xfr->reqtype == dns_rdatatype_ixfr) {
    /* Get the SOA and add it to the authority section. */
    dns_db_currentversion(xfr->db, &ver);
    CHECK(dns_db_createsoatuple(xfr->db, ver, xfr->mctx,
              DNS_DIFFOP_EXISTS, &soatuple));
    xfr->ixfr.request_serial = dns_soa_getserial(&soatuple->rdata);
    xfr->ixfr.current_serial = xfr->ixfr.request_serial;
    xfrin_log(xfr, ISC_LOG_DEBUG(3),
        "requesting IXFR for serial %u",
        xfr->ixfr.request_serial);

    tuple2msgname(soatuple, msg, &msgsoaname);
    dns_message_addname(msg, msgsoaname, DNS_SECTION_AUTHORITY);
  } else if (xfr->reqtype == dns_rdatatype_soa) {
    CHECK(dns_db_getsoaserial(xfr->db, NULL,
            &xfr->ixfr.request_serial));
  }

  if (edns && xfr->view->peers != NULL) {
    dns_peer_t *peer = NULL;
    isc_netaddr_t primaryip;
    isc_netaddr_fromsockaddr(&primaryip, &xfr->primaryaddr);
    result = dns_peerlist_peerbyaddr(xfr->view->peers, &primaryip,
             &peer);
    if (result == ISC_R_SUCCESS) {
      (void)dns_peer_getsupportedns(peer, &edns);
      (void)dns_peer_getudpsize(peer, &udpsize);
      (void)dns_peer_getrequestnsid(peer, &reqnsid);
      (void)dns_peer_getrequestexpire(peer, &reqexpire);
    }
  }

  if (edns) {
    CHECK(add_opt(msg, udpsize, reqnsid, reqexpire));
  }

  atomic_store_relaxed(&xfr->nmsg, 0);
  atomic_store_relaxed(&xfr->nrecs, 0);
  atomic_store_relaxed(&xfr->nbytes, 0);
  atomic_store_relaxed(&xfr->start, isc_time_now());

  xfr->nbytes_saved = 0;

  msg->id = xfr->id;
  CHECK(render(msg, xfr->mctx, &xfr->qbuffer));

  /*
   * Free the last tsig, if there is one.
   */
  if (xfr->lasttsig != NULL) {
    isc_buffer_free(&xfr->lasttsig);
  }

  /*
   * Save the query TSIG and don't let message_destroy free it.
   */
  CHECK(dns_message_getquerytsig(msg, xfr->mctx, &xfr->lasttsig));

  isc_buffer_usedregion(&xfr->qbuffer, &region);
  INSIST(region.length <= 65535);

  dns_xfrin_ref(xfr);
  dns_dispatch_send(xfr->dispentry, &region);
  xfrin_log(xfr, ISC_LOG_DEBUG(3), "sending %s request, QID %d",
      request_type(xfr), xfr->id);

cleanup:
  dns_message_detach(&msg);
  if (soatuple != NULL) {
    dns_difftuple_free(&soatuple);
  }
  if (ver != NULL) {
    dns_db_closeversion(xfr->db, &ver, false);
  }

  return result;
}

static void
xfrin_send_done(isc_result_t result, isc_region_t *region, void *arg) {
  dns_xfrin_t *xfr = (dns_xfrin_t *)arg;

  UNUSED(region);

  REQUIRE(VALID_XFRIN(xfr));

  if (atomic_load(&xfr->shuttingdown)) {
    result = ISC_R_SHUTTINGDOWN;
  }

  LIBDNS_XFRIN_SENT(xfr, xfr->info, result);

  CHECK(result);

  xfrin_log(xfr, ISC_LOG_DEBUG(3), "sent request data");

cleanup:
  if (result != ISC_R_SUCCESS) {
    xfrin_fail(xfr, result, "failed sending request data");
  }

  dns_xfrin_detach(&xfr);
}

static void
get_edns_expire(dns_xfrin_t *xfr, dns_message_t *msg) {
  isc_result_t result;
  dns_rdata_t rdata = DNS_RDATA_INIT;
  isc_buffer_t optbuf;
  uint16_t optcode;
  uint16_t optlen;

  result = dns_rdataset_first(msg->opt);
  if (result == ISC_R_SUCCESS) {
    dns_rdataset_current(msg->opt, &rdata);
    isc_buffer_init(&optbuf, rdata.data, rdata.length);
    isc_buffer_add(&optbuf, rdata.length);
    while (isc_buffer_remaininglength(&optbuf) >= 4) {
      optcode = isc_buffer_getuint16(&optbuf);
      optlen = isc_buffer_getuint16(&optbuf);
      /*
       * A EDNS EXPIRE response has a length of 4.
       */
      if (optcode != DNS_OPT_EXPIRE || optlen != 4) {
        isc_buffer_forward(&optbuf, optlen);
        continue;
      }
      xfr->expireopt = isc_buffer_getuint32(&optbuf);
      xfr->expireoptset = true;
      dns_zone_log(xfr->zone, ISC_LOG_DEBUG(1),
             "got EDNS EXPIRE of %u", xfr->expireopt);
      break;
    }
  }
}

static void
xfrin_end(dns_xfrin_t *xfr, isc_result_t result) {
  /* Inform the caller. */
  if (xfr->done != NULL) {
    LIBDNS_XFRIN_DONE_CALLBACK_BEGIN(xfr, xfr->info, result);
    (xfr->done)(xfr->zone,
          xfr->expireoptset ? &xfr->expireopt : NULL, result);
    xfr->done = NULL;
    LIBDNS_XFRIN_DONE_CALLBACK_END(xfr, xfr->info, result);
  }

  atomic_store(&xfr->shuttingdown, true);

  if (xfr->max_time_timer != NULL) {
    isc_timer_stop(xfr->max_time_timer);
    isc_timer_destroy(&xfr->max_time_timer);
  }
  if (xfr->max_idle_timer != NULL) {
    isc_timer_stop(xfr->max_idle_timer);
    isc_timer_destroy(&xfr->max_idle_timer);
  }
  if (xfr->min_rate_timer != NULL) {
    isc_timer_stop(xfr->min_rate_timer);
    isc_timer_destroy(&xfr->min_rate_timer);
  }

  if (xfr->shutdown_result == ISC_R_UNSET) {
    xfr->shutdown_result = result;
  }
}

static void
xfrin_recv_done(isc_result_t result, isc_region_t *region, void *arg) {
  dns_xfrin_t *xfr = (dns_xfrin_t *)arg;
  dns_message_t *msg = NULL;
  isc_buffer_t buffer;

  REQUIRE(VALID_XFRIN(xfr));

  if (atomic_load(&xfr->shuttingdown)) {
    result = ISC_R_SHUTTINGDOWN;
  }

  /* Stop the idle timer */
  isc_timer_stop(xfr->max_idle_timer);

  LIBDNS_XFRIN_RECV_START(xfr, xfr->info, result);

  CHECK(result);

  xfrin_log(xfr, ISC_LOG_DEBUG(7), "received %u bytes", region->length);

  dns_message_create(xfr->mctx, NULL, NULL, DNS_MESSAGE_INTENTPARSE,
         &msg);

  CHECK(dns_message_settsigkey(msg, xfr->tsigkey));
  dns_message_setquerytsig(msg, xfr->lasttsig);

  dns_message_setclass(msg, xfr->rdclass);

  msg->tcp_continuation = (atomic_load_relaxed(&xfr->nmsg) > 0) ? 1 : 0;

  isc_buffer_init(&buffer, region->base, region->length);
  isc_buffer_add(&buffer, region->length);

  result = dns_message_parse(msg, &buffer,
           DNS_MESSAGEPARSE_PRESERVEORDER);
  if (result == ISC_R_SUCCESS) {
    dns_message_logpacketfrom(
      msg, "received message", &xfr->primaryaddr,
      DNS_LOGCATEGORY_XFER_IN, DNS_LOGMODULE_XFER_IN,
      ISC_LOG_DEBUG(10), xfr->mctx);
  } else {
    xfrin_log(xfr, ISC_LOG_DEBUG(10), "dns_message_parse: %s",
        isc_result_totext(result));
  }

  LIBDNS_XFRIN_RECV_PARSED(xfr, xfr->info, result);

  /* Authenticate before stateful response handling. */
  if (result == ISC_R_SUCCESS) {
    result = dns_message_checksig(msg, xfr->view);
    if (result != ISC_R_SUCCESS) {
      xfrin_log(xfr, ISC_LOG_DEBUG(3),
          "TSIG check failed: %s",
          isc_result_totext(result));
      goto cleanup;
    }
    if (dns_message_gettsigkey(msg) != NULL &&
        dns_message_gettsig(msg, NULL) == NULL)
    {
      CLEANUP(DNS_R_EXPECTEDTSIG);
    }
  }

  if (result != ISC_R_SUCCESS || msg->rcode != dns_rcode_noerror ||
      msg->opcode != dns_opcode_query || msg->rdclass != xfr->rdclass)
  {
    if (result == ISC_R_SUCCESS &&
        msg->rcode == dns_rcode_formerr && xfr->edns &&
        (atomic_load(&xfr->state) == XFRST_SOAQUERY ||
         atomic_load(&xfr->state) == XFRST_ZONEXFRREQUEST))
    {
      xfr->edns = false;
      dns_message_detach(&msg);
      /*
       * With these states (see the conditions above) the diff
       * process can't be currently in the running state, so
       * it is safe to reset the 'xfr' and retry right away.
       */
      xfrin_reset(xfr);
      goto try_again;
    } else if (result == ISC_R_SUCCESS &&
         msg->rcode != dns_rcode_noerror)
    {
      result = dns_result_fromrcode(msg->rcode);
    } else if (result == ISC_R_SUCCESS &&
         msg->opcode != dns_opcode_query)
    {
      result = DNS_R_UNEXPECTEDOPCODE;
    } else if (result == ISC_R_SUCCESS &&
         msg->rdclass != xfr->rdclass)
    {
      result = DNS_R_BADCLASS;
    } else if (result == ISC_R_SUCCESS || result == DNS_R_NOERROR) {
      result = DNS_R_UNEXPECTEDID;
    }

    if (xfr->reqtype == dns_rdatatype_axfr ||
        xfr->reqtype == dns_rdatatype_soa)
    {
      goto cleanup;
    }

    xfrin_log(xfr, ISC_LOG_DEBUG(3), "got %s, retrying with AXFR",
        isc_result_totext(result));
  try_axfr:
    LIBDNS_XFRIN_RECV_TRY_AXFR(xfr, xfr->info, result);
    dns_message_detach(&msg);
    /* If there is a running worker thread then delay the retry. */
    if (xfr->diff_running) {
      xfr->retry_axfr = true;
      dns_xfrin_detach(&xfr);
      return;
    }
    xfrin_reset(xfr);
    xfr->reqtype = dns_rdatatype_soa;
    atomic_store(&xfr->state, XFRST_SOAQUERY);
  try_again:
    result = xfrin_start(xfr);
    if (result != ISC_R_SUCCESS) {
      xfrin_fail(xfr, result, "failed setting up socket");
    }
    dns_xfrin_detach(&xfr);
    return;
  }

  /*
   * The question section should exist for SOA and in the first
   * message of a AXFR or IXFR response.  The question section
   * may exist in the 2nd and subsequent messages in a AXFR or
   * IXFR response.  If the question section exists it should
   * match the question that was sent.
   */
  if (msg->counts[DNS_SECTION_QUESTION] > 1) {
    xfrin_log(xfr, ISC_LOG_NOTICE, "too many questions (%u)",
        msg->counts[DNS_SECTION_QUESTION]);
    CLEANUP(DNS_R_FORMERR);
  }

  if ((atomic_load(&xfr->state) == XFRST_SOAQUERY ||
       atomic_load(&xfr->state) == XFRST_ZONEXFRREQUEST) &&
      msg->counts[DNS_SECTION_QUESTION] != 1)
  {
    xfrin_log(xfr, ISC_LOG_NOTICE, "missing question section");
    CLEANUP(DNS_R_FORMERR);
  }

  MSG_SECTION_FOREACH(msg, DNS_SECTION_QUESTION, name) {
    dns_rdataset_t *rds = NULL;

    LIBDNS_XFRIN_RECV_QUESTION(xfr, xfr->info, msg);

    if (!dns_name_equal(name, &xfr->name)) {
      xfrin_log(xfr, ISC_LOG_NOTICE,
          "question name mismatch");
      CLEANUP(DNS_R_FORMERR);
    }
    rds = ISC_LIST_HEAD(name->list);
    INSIST(rds != NULL);
    if (rds->type != xfr->reqtype) {
      xfrin_log(xfr, ISC_LOG_NOTICE,
          "question type mismatch");
      CLEANUP(DNS_R_FORMERR);
    }
    if (rds->rdclass != xfr->rdclass) {
      xfrin_log(xfr, ISC_LOG_NOTICE,
          "question class mismatch");
      CLEANUP(DNS_R_FORMERR);
    }
  }

  /*
   * Does the server know about IXFR?  If it doesn't we will get
   * a message with a empty answer section or a potentially a CNAME /
   * DNAME, the later is handled by xfr_rr() which will return FORMERR
   * if the first RR in the answer section is not a SOA record.
   */
  if (xfr->reqtype == dns_rdatatype_ixfr &&
      atomic_load(&xfr->state) == XFRST_ZONEXFRREQUEST &&
      msg->counts[DNS_SECTION_ANSWER] == 0)
  {
    xfrin_log(xfr, ISC_LOG_DEBUG(3),
        "empty answer section, retrying with AXFR");
    goto try_axfr;
  }

  if (xfr->reqtype == dns_rdatatype_soa &&
      (msg->flags & DNS_MESSAGEFLAG_AA) == 0)
  {
    CLEANUP(DNS_R_NOTAUTHORITATIVE);
  }

  MSG_SECTION_FOREACH(msg, DNS_SECTION_ANSWER, name) {
    LIBDNS_XFRIN_RECV_ANSWER(xfr, xfr->info, msg);

    ISC_LIST_FOREACH(name->list, rds, link) {
      DNS_RDATASET_FOREACH(rds) {
        dns_rdata_t rdata = DNS_RDATA_INIT;
        dns_rdataset_current(rds, &rdata);
        CHECK(xfr_rr(xfr, dns_name(name), rds->ttl,
               &rdata));

        /*
         * Did we hit the maximum ixfr diffs limit?
         */
        if (xfr->reqtype == dns_rdatatype_ixfr &&
            xfr->ixfr.maxdiffs != 0 &&
            xfr->ixfr.diffs >= xfr->ixfr.maxdiffs)
        {
          xfrin_log(xfr, ISC_LOG_DEBUG(3),
              "too many diffs, "
              "retrying with AXFR");
          goto try_axfr;
        }
      }
    }
  }

  if (dns_message_gettsig(msg, NULL) != NULL) {
    /*
     * Free the last tsig, if there is one.
     */
    if (xfr->lasttsig != NULL) {
      isc_buffer_free(&xfr->lasttsig);
    }

    /*
     * Update the last tsig pointer.
     */
    CHECK(dns_message_getquerytsig(msg, xfr->mctx, &xfr->lasttsig));
  }

  /*
   * Update the number of messages and bytes received.
   */
  atomic_fetch_add_relaxed(&xfr->nmsg, 1);
  atomic_fetch_add_relaxed(&xfr->nbytes, buffer.used);

  if (!xfr->expireoptset && msg->opt != NULL) {
    get_edns_expire(xfr, msg);
  }

  switch (atomic_load(&xfr->state)) {
  case XFRST_GOTSOA:
    xfr->reqtype = dns_rdatatype_axfr;
    atomic_store(&xfr->state, XFRST_ZONEXFRREQUEST);
    CHECK(xfrin_start(xfr));
    break;
  case XFRST_AXFR_END:
  case XFRST_IXFR_END:
    /* We are at the end, cancel the timers and IO */
    isc_timer_stop(xfr->min_rate_timer);
    isc_timer_stop(xfr->max_idle_timer);
    isc_timer_stop(xfr->max_time_timer);
    xfrin_cancelio(xfr);
    break;
  default:
    /*
     * Read the next message.
     */
    dns_message_detach(&msg);
    CHECK(dns_dispatch_getnext(xfr->dispentry));

    isc_interval_t interval;
    isc_interval_set(&interval, dns_zone_getidlein(xfr->zone), 0);
    isc_timer_start(xfr->max_idle_timer, isc_timertype_once,
        &interval);

    LIBDNS_XFRIN_READ(xfr, xfr->info, result);
    return;
  }

cleanup:
  if (result != ISC_R_SUCCESS) {
    xfrin_fail(xfr, result, "failed while receiving responses");
  }

  if (msg != NULL) {
    dns_message_detach(&msg);
  }
  LIBDNS_XFRIN_RECV_DONE(xfr, xfr->info, result);
  dns_xfrin_detach(&xfr);
}

static void
xfrin_ixfrcleanup(dns_xfrin_t *xfr) {
  isc_queue_t diff_queue;

  /* Leave the shared queue empty before freeing its entries. */
  isc_queue_init(&diff_queue);
  if (!isc_queue_splice(&diff_queue, &xfr->diff_queue)) {
    return;
  }

  ixfr_apply_data_t *data = NULL, *next = NULL;
  isc_queue_for_each_entry_safe(&diff_queue, data, next, queue_node) {
    /* We need to clear and free all data chunks */
    dns_diff_clear(&data->diff);
    isc_mem_put(xfr->mctx, data, sizeof(*data));
  }
}

static void
xfrin_destroy(dns_xfrin_t *xfr) {
  uint64_t msecs, persec;
  isc_time_t now = isc_time_now();
  char expireopt[sizeof("4000000000")] = { 0 };
  const char *sep = "";

  REQUIRE(VALID_XFRIN(xfr));

  /* Safe-guards */
  REQUIRE(atomic_load(&xfr->shuttingdown));

  INSIST(xfr->shutdown_result != ISC_R_UNSET);

  /*
   * If we're called through dns_xfrin_detach() and are not
   * shutting down, we can't know what the transfer status is as
   * we are only called when the last reference is lost.
   */
  xfrin_log(xfr, ISC_LOG_INFO, "Transfer status: %s",
      isc_result_totext(xfr->shutdown_result));

  /*
   * Calculate the length of time the transfer took,
   * and print a log message with the bytes and rate.
   */
  isc_time_t start = atomic_load_relaxed(&xfr->start);
  msecs = isc_time_microdiff(&now, &start) / 1000;
  if (msecs == 0) {
    msecs = 1;
  }
  persec = (atomic_load_relaxed(&xfr->nbytes) * 1000) / msecs;

  if (xfr->expireoptset) {
    sep = ", expire option ";
    snprintf(expireopt, sizeof(expireopt), "%u", xfr->expireopt);
  }

  xfrin_log(xfr, ISC_LOG_INFO,
      "Transfer completed: %d messages, %d records, "
      "%" PRIu64 " bytes, "
      "%u.%03u secs (%u bytes/sec) (serial %" PRIuFAST32 "%s%s)",
      atomic_load_relaxed(&xfr->nmsg),
      atomic_load_relaxed(&xfr->nrecs),
      atomic_load_relaxed(&xfr->nbytes),
      (unsigned int)(msecs / 1000), (unsigned int)(msecs % 1000),
      (unsigned int)persec, atomic_load_relaxed(&xfr->end_serial),
      sep, expireopt);

  /* Cleanup unprocessed IXFR data */
  xfrin_ixfrcleanup(xfr);

  /* Cleanup unprocessed AXFR data */
  dns_diff_clear(&xfr->diff);

  xfrin_cancelio(xfr);

  if (xfr->transport != NULL) {
    dns_transport_detach(&xfr->transport);
  }

  if (xfr->tsigkey != NULL) {
    dns_tsigkey_detach(&xfr->tsigkey);
  }

  if (xfr->lasttsig != NULL) {
    isc_buffer_free(&xfr->lasttsig);
  }

  if (xfr->ixfr.journal != NULL) {
    dns_journal_destroy(&xfr->ixfr.journal);
  }

  if (xfr->axfr.add_private != NULL) {
    (void)dns_db_endload(xfr->db, &xfr->axfr);
  }

  if (xfr->name.attributes.dynamic) {
    dns_name_free(&xfr->name, xfr->mctx);
  }

  if (xfr->ver != NULL) {
    dns_db_closeversion(xfr->db, &xfr->ver, false);
  }

  if (xfr->db != NULL) {
    dns_db_detach(&xfr->db);
  }

  if (xfr->zone != NULL) {
    if (!xfr->zone_had_db &&
        xfr->shutdown_result == ISC_R_SUCCESS &&
        dns_zone_gettype(xfr->zone) == dns_zone_mirror)
    {
      dns_zone_log(xfr->zone, ISC_LOG_INFO,
             "mirror zone is now in use");
    }
    xfrin_log(xfr, ISC_LOG_DEBUG(99), "freeing transfer context");
    /*
     * xfr->zone must not be detached before xfrin_log() is called.
     */
    dns_zone_idetach(&xfr->zone);
  }

  if (xfr->view != NULL) {
    dns_view_weakdetach(&xfr->view);
  }

  if (xfr->firstsoa_data != NULL) {
    isc_mem_free(xfr->mctx, xfr->firstsoa_data);
  }

  if (xfr->tlsctx_cache != NULL) {
    isc_tlsctx_cache_detach(&xfr->tlsctx_cache);
  }

  INSIST(xfr->max_time_timer == NULL);
  INSIST(xfr->max_idle_timer == NULL);
  INSIST(xfr->min_rate_timer == NULL);

  isc_loop_detach(&xfr->loop);

  isc_mem_putanddetach(&xfr->mctx, xfr, sizeof(*xfr));
}

/*
 * Log incoming zone transfer messages in a format like
 * transfer of <zone> from <address>: <message>
 */

static void
xfrin_log(dns_xfrin_t *xfr, int level, const char *fmt, ...) {
  va_list ap;
  char primarytext[ISC_SOCKADDR_FORMATSIZE];
  char msgtext[2048];

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

  isc_sockaddr_format(&xfr->primaryaddr, primarytext,
          sizeof(primarytext));
  va_start(ap, fmt);
  vsnprintf(msgtext, sizeof(msgtext), fmt, ap);
  va_end(ap);

  isc_log_write(DNS_LOGCATEGORY_XFER_IN, DNS_LOGMODULE_XFER_IN, level,
          "%p: transfer of '%s' from %s: %s", xfr, xfr->info,
          primarytext, msgtext);
}

Coverage Report

Created: 2026-10-28 06:55