/src/bind9/lib/dns/tsig.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 <stdlib.h>

#include <isc/buffer.h>
#include <isc/hashmap.h>
#include <isc/log.h>
#include <isc/mem.h>
#include <isc/refcount.h>
#include <isc/result.h>
#include <isc/serial.h>
#include <isc/string.h>
#include <isc/time.h>
#include <isc/util.h>

#include <dns/fixedname.h>
#include <dns/keyvalues.h>
#include <dns/message.h>
#include <dns/rdata.h>
#include <dns/rdatalist.h>
#include <dns/rdataset.h>
#include <dns/rdatastruct.h>
#include <dns/tsig.h>

#include "tsig_p.h"

#define TSIGKEYRING_MAGIC    ISC_MAGIC('T', 'K', 'R', 'g')
#define VALID_TSIGKEYRING(x) ISC_MAGIC_VALID(x, TSIGKEYRING_MAGIC)

#define TSIG_MAGIC   ISC_MAGIC('T', 'S', 'I', 'G')
#define VALID_TSIGKEY(x) ISC_MAGIC_VALID(x, TSIG_MAGIC)

#define is_response(msg) ((msg->flags & DNS_MESSAGEFLAG_QR) != 0)

#define BADTIMELEN 6

static unsigned char hmacmd5_ndata[] = "\010hmac-md5\007sig-alg\003reg\003int";

static dns_name_t const hmacmd5 = DNS_NAME_INITABSOLUTE(hmacmd5_ndata);
const dns_name_t *dns_tsig_hmacmd5_name = &hmacmd5;

static unsigned char gsstsig_ndata[] = "\010gss-tsig";
static dns_name_t const gsstsig = DNS_NAME_INITABSOLUTE(gsstsig_ndata);
const dns_name_t *dns_tsig_gssapi_name = &gsstsig;

static unsigned char hmacsha1_ndata[] = "\011hmac-sha1";
static dns_name_t const hmacsha1 = DNS_NAME_INITABSOLUTE(hmacsha1_ndata);
const dns_name_t *dns_tsig_hmacsha1_name = &hmacsha1;

static unsigned char hmacsha224_ndata[] = "\013hmac-sha224";
static dns_name_t const hmacsha224 = DNS_NAME_INITABSOLUTE(hmacsha224_ndata);
const dns_name_t *dns_tsig_hmacsha224_name = &hmacsha224;

static unsigned char hmacsha256_ndata[] = "\013hmac-sha256";
static dns_name_t const hmacsha256 = DNS_NAME_INITABSOLUTE(hmacsha256_ndata);
const dns_name_t *dns_tsig_hmacsha256_name = &hmacsha256;

static unsigned char hmacsha384_ndata[] = "\013hmac-sha384";
static dns_name_t const hmacsha384 = DNS_NAME_INITABSOLUTE(hmacsha384_ndata);
const dns_name_t *dns_tsig_hmacsha384_name = &hmacsha384;

static unsigned char hmacsha512_ndata[] = "\013hmac-sha512";
static dns_name_t const hmacsha512 = DNS_NAME_INITABSOLUTE(hmacsha512_ndata);
const dns_name_t *dns_tsig_hmacsha512_name = &hmacsha512;

static const struct {
  const dns_name_t *name;
  unsigned int dstalg;
} known_algs[] = { { &hmacmd5, DST_ALG_HMACMD5 },
       { &gsstsig, DST_ALG_GSSAPI },
       { &hmacsha1, DST_ALG_HMACSHA1 },
       { &hmacsha224, DST_ALG_HMACSHA224 },
       { &hmacsha256, DST_ALG_HMACSHA256 },
       { &hmacsha384, DST_ALG_HMACSHA384 },
       { &hmacsha512, DST_ALG_HMACSHA512 } };

static isc_result_t
tsig_verify_tcp(isc_buffer_t *source, dns_message_t *msg);

static void
tsig_log(dns_tsigkey_t *key, int level, const char *fmt, ...)
  ISC_FORMAT_PRINTF(3, 4);

bool
dns__tsig_algvalid(unsigned int alg) {
  return alg == DST_ALG_HMACMD5 || alg == DST_ALG_HMACSHA1 ||
         alg == DST_ALG_HMACSHA224 || alg == DST_ALG_HMACSHA256 ||
         alg == DST_ALG_HMACSHA384 || alg == DST_ALG_HMACSHA512;
}

static void
tsig_log(dns_tsigkey_t *key, int level, const char *fmt, ...) {
  va_list ap;
  char message[4096];
  char namestr[DNS_NAME_FORMATSIZE];
  char creatorstr[DNS_NAME_FORMATSIZE];

  if (!isc_log_wouldlog(level)) {
    return;
  }
  if (key != NULL) {
    dns_name_format(key->name, namestr, sizeof(namestr));
  } else {
    strlcpy(namestr, "<null>", sizeof(namestr));
  }

  if (key != NULL && key->generated && key->creator != NULL) {
    dns_name_format(key->creator, creatorstr, sizeof(creatorstr));
  } else {
    strlcpy(creatorstr, "<null>", sizeof(creatorstr));
  }

  va_start(ap, fmt);
  vsnprintf(message, sizeof(message), fmt, ap);
  va_end(ap);
  if (key != NULL && key->generated) {
    isc_log_write(DNS_LOGCATEGORY_DNSSEC, DNS_LOGMODULE_TSIG, level,
            "tsig key '%s' (%s): %s", namestr, creatorstr,
            message);
  } else {
    isc_log_write(DNS_LOGCATEGORY_DNSSEC, DNS_LOGMODULE_TSIG, level,
            "tsig key '%s': %s", namestr, message);
  }
}

static bool
tkey_match(void *node, const void *key) {
  dns_tsigkey_t *tkey = node;

  return dns_name_equal(tkey->name, key);
}

static bool
match_ptr(void *node, const void *key) {
  return node == key;
}

static void
rm_hashmap(dns_tsigkey_t *tkey) {
  REQUIRE(VALID_TSIGKEY(tkey));
  REQUIRE(VALID_TSIGKEYRING(tkey->ring));

  (void)isc_hashmap_delete(tkey->ring->keys, dns_name_hash(tkey->name),
         match_ptr, tkey);
  dns_tsigkey_detach(&tkey);
}

static void
rm_lru(dns_tsigkey_t *tkey) {
  REQUIRE(VALID_TSIGKEY(tkey));
  REQUIRE(VALID_TSIGKEYRING(tkey->ring));

  if (tkey->generated && ISC_LINK_LINKED(tkey, link)) {
    ISC_LIST_UNLINK(tkey->ring->lru, tkey, link);
    tkey->ring->generated--;
    dns_tsigkey_unref(tkey);
  }
}

static void
adjust_lru(dns_tsigkey_t *tkey) {
  if (tkey->generated) {
    RWLOCK(&tkey->ring->lock, isc_rwlocktype_write);
    /*
     * We may have been removed from the LRU list between
     * removing the read lock and acquiring the write lock.
     */
    if (ISC_LINK_LINKED(tkey, link) && tkey->ring->lru.tail != tkey)
    {
      ISC_LIST_UNLINK(tkey->ring->lru, tkey, link);
      ISC_LIST_APPEND(tkey->ring->lru, tkey, link);
    }
    RWUNLOCK(&tkey->ring->lock, isc_rwlocktype_write);
  }
}

isc_result_t
dns_tsigkey_createfromkey(const dns_name_t *name, dst_algorithm_t algorithm,
        dst_key_t *dstkey, bool generated, bool restored,
        const dns_name_t *creator, isc_stdtime_t inception,
        isc_stdtime_t expire, isc_mem_t *mctx,
        dns_tsigkey_t **keyp) {
  dns_tsigkey_t *tkey = NULL;
  isc_result_t result;

  REQUIRE(keyp != NULL && *keyp == NULL);
  REQUIRE(name != NULL);
  REQUIRE(mctx != NULL);

  tkey = isc_mem_get(mctx, sizeof(dns_tsigkey_t));
  *tkey = (dns_tsigkey_t){
    .generated = generated,
    .restored = restored,
    .inception = inception,
    .expire = expire,
    .alg = algorithm,
    .algname = DNS_NAME_INITEMPTY,
    .link = ISC_LINK_INITIALIZER,
  };

  tkey->name = dns_fixedname_initname(&tkey->fn);
  dns_name_copy(name, tkey->name);
  (void)dns_name_downcase(tkey->name, tkey->name);

  if (algorithm != DST_ALG_UNKNOWN) {
    if (dstkey != NULL && dst_key_alg(dstkey) != algorithm) {
      result = DNS_R_BADALG;
      goto cleanup_name;
    }
  } else if (dstkey != NULL) {
    result = DNS_R_BADALG;
    goto cleanup_name;
  }

  if (creator != NULL) {
    tkey->creator = isc_mem_get(mctx, sizeof(dns_name_t));
    dns_name_init(tkey->creator);
    dns_name_dup(creator, mctx, tkey->creator);
  }

  if (dstkey != NULL) {
    dst_key_attach(dstkey, &tkey->key);
  }

  isc_refcount_init(&tkey->references, 1);
  isc_mem_attach(mctx, &tkey->mctx);

  /*
   * Ignore this if it's a GSS key, since the key size is meaningless.
   */
  if (dstkey != NULL && dst_key_size(dstkey) < 64 &&
      algorithm != DST_ALG_GSSAPI)
  {
    char namestr[DNS_NAME_FORMATSIZE];
    dns_name_format(name, namestr, sizeof(namestr));
    isc_log_write(DNS_LOGCATEGORY_DNSSEC, DNS_LOGMODULE_TSIG,
            ISC_LOG_INFO,
            "the key '%s' is too short to be secure",
            namestr);
  }

  tkey->magic = TSIG_MAGIC;

  if (tkey->restored) {
    tsig_log(tkey, ISC_LOG_DEBUG(3), "restored from file");
  } else if (tkey->generated) {
    tsig_log(tkey, ISC_LOG_DEBUG(3), "generated");
  } else {
    tsig_log(tkey, ISC_LOG_DEBUG(3), "statically configured");
  }

  SET_IF_NOT_NULL(keyp, tkey);
  return ISC_R_SUCCESS;

cleanup_name:
  isc_mem_put(mctx, tkey, sizeof(dns_tsigkey_t));

  return result;
}

static void
destroyring(dns_tsigkeyring_t *ring) {
  isc_result_t result;
  isc_hashmap_iter_t *it = NULL;

  RWLOCK(&ring->lock, isc_rwlocktype_write);
  isc_hashmap_iter_create(ring->keys, &it);
  for (result = isc_hashmap_iter_first(it); result == ISC_R_SUCCESS;
       result = isc_hashmap_iter_delcurrent_next(it))
  {
    dns_tsigkey_t *tkey = NULL;
    isc_hashmap_iter_current(it, (void **)&tkey);
    rm_lru(tkey);
    dns_tsigkey_detach(&tkey);
  }
  isc_hashmap_iter_destroy(&it);
  isc_hashmap_destroy(&ring->keys);
  RWUNLOCK(&ring->lock, isc_rwlocktype_write);

  ring->magic = 0;

  isc_rwlock_destroy(&ring->lock);
  isc_mem_putanddetach(&ring->mctx, ring, sizeof(dns_tsigkeyring_t));
}

#if DNS_TSIG_TRACE
ISC_REFCOUNT_TRACE_IMPL(dns_tsigkeyring, destroyring);
#else
ISC_REFCOUNT_IMPL(dns_tsigkeyring, destroyring);
#endif

/*
 * Look up the DST_ALG_ constant for a given name.
 */
dst_algorithm_t
dns__tsig_algfromname(const dns_name_t *algorithm) {
  for (size_t i = 0; i < ARRAY_SIZE(known_algs); ++i) {
    const dns_name_t *name = known_algs[i].name;
    if (algorithm == name || dns_name_equal(algorithm, name)) {
      return known_algs[i].dstalg;
    }
  }
  return DST_ALG_UNKNOWN;
}

static isc_result_t
restore_key(dns_tsigkeyring_t *ring, isc_stdtime_t now, FILE *fp) {
  dst_key_t *dstkey = NULL;
  char namestr[1024];
  char creatorstr[1024];
  char algorithmstr[1024];
  char keystr[4096];
  unsigned int inception, expire;
  int n;
  isc_buffer_t b;
  dns_name_t *name = NULL, *creator = NULL, *algorithm = NULL;
  dns_fixedname_t fname, fcreator, falgorithm;
  isc_result_t result;
  unsigned int dstalg;
  dns_tsigkey_t *tkey = NULL;

  n = fscanf(fp, "%1023s %1023s %u %u %1023s %4095s\n", namestr,
       creatorstr, &inception, &expire, algorithmstr, keystr);
  if (n == EOF) {
    return ISC_R_NOMORE;
  }
  if (n != 6) {
    return ISC_R_FAILURE;
  }

  if (isc_serial_lt(expire, now)) {
    return DNS_R_EXPIRED;
  }

  name = dns_fixedname_initname(&fname);
  isc_buffer_init(&b, namestr, strlen(namestr));
  isc_buffer_add(&b, strlen(namestr));
  result = dns_name_fromtext(name, &b, dns_rootname, 0);
  if (result != ISC_R_SUCCESS) {
    return result;
  }

  creator = dns_fixedname_initname(&fcreator);
  isc_buffer_init(&b, creatorstr, strlen(creatorstr));
  isc_buffer_add(&b, strlen(creatorstr));
  result = dns_name_fromtext(creator, &b, dns_rootname, 0);
  if (result != ISC_R_SUCCESS) {
    return result;
  }

  algorithm = dns_fixedname_initname(&falgorithm);
  isc_buffer_init(&b, algorithmstr, strlen(algorithmstr));
  isc_buffer_add(&b, strlen(algorithmstr));
  result = dns_name_fromtext(algorithm, &b, dns_rootname, 0);
  if (result != ISC_R_SUCCESS) {
    return result;
  }

  dstalg = dns__tsig_algfromname(algorithm);
  if (dstalg == DST_ALG_UNKNOWN) {
    return DNS_R_BADALG;
  }

  result = dst_key_restore(name, dstalg, DNS_KEYOWNER_ENTITY,
         DNS_KEYPROTO_DNSSEC, dns_rdataclass_in,
         ring->mctx, keystr, &dstkey);
  if (result != ISC_R_SUCCESS) {
    return result;
  }

  result = dns_tsigkey_createfromkey(name, dstalg, dstkey, true, true,
             creator, inception, expire,
             ring->mctx, &tkey);
  if (result == ISC_R_SUCCESS) {
    result = dns_tsigkeyring_add(ring, tkey);
  }
  dns_tsigkey_detach(&tkey);
  if (dstkey != NULL) {
    dst_key_free(&dstkey);
  }
  return result;
}

static void
dump_key(dns_tsigkey_t *tkey, FILE *fp) {
  char *buffer = NULL;
  int length = 0;
  char namestr[DNS_NAME_FORMATSIZE];
  char creatorstr[DNS_NAME_FORMATSIZE];
  char algorithmstr[DNS_NAME_FORMATSIZE];
  isc_result_t result;

  REQUIRE(tkey != NULL);
  REQUIRE(fp != NULL);

  dns_name_format(tkey->name, namestr, sizeof(namestr));
  dns_name_format(tkey->creator, creatorstr, sizeof(creatorstr));
  dns_name_format(dns_tsigkey_algorithm(tkey), algorithmstr,
      sizeof(algorithmstr));
  result = dst_key_dump(tkey->key, tkey->mctx, &buffer, &length);
  if (result == ISC_R_SUCCESS) {
    fprintf(fp, "%s %s %u %u %s %.*s\n", namestr, creatorstr,
      tkey->inception, tkey->expire, algorithmstr, length,
      buffer);
  }
  if (buffer != NULL) {
    isc_mem_put(tkey->mctx, buffer, length);
  }
}

isc_result_t
dns_tsigkeyring_dump(dns_tsigkeyring_t *ring, FILE *fp) {
  isc_result_t result;
  isc_stdtime_t now = isc_stdtime_now();
  isc_hashmap_iter_t *it = NULL;
  bool found = false;

  REQUIRE(VALID_TSIGKEYRING(ring));

  RWLOCK(&ring->lock, isc_rwlocktype_read);
  isc_hashmap_iter_create(ring->keys, &it);
  for (result = isc_hashmap_iter_first(it); result == ISC_R_SUCCESS;
       result = isc_hashmap_iter_next(it))
  {
    dns_tsigkey_t *tkey = NULL;
    isc_hashmap_iter_current(it, (void **)&tkey);

    if (tkey->generated && tkey->expire >= now) {
      dump_key(tkey, fp);
      found = true;
    }
  }
  isc_hashmap_iter_destroy(&it);
  RWUNLOCK(&ring->lock, isc_rwlocktype_read);

  return found ? ISC_R_SUCCESS : ISC_R_NOTFOUND;
}

const dns_name_t *
dns_tsigkey_identity(const dns_tsigkey_t *tsigkey) {
  REQUIRE(tsigkey == NULL || VALID_TSIGKEY(tsigkey));

  if (tsigkey == NULL) {
    return NULL;
  }
  if (tsigkey->generated) {
    return tsigkey->creator;
  } else {
    return tsigkey->name;
  }
}

isc_result_t
dns_tsigkey_create(const dns_name_t *name, dst_algorithm_t algorithm,
       unsigned char *secret, int length, isc_mem_t *mctx,
       dns_tsigkey_t **key) {
  dst_key_t *dstkey = NULL;
  isc_result_t result;

  REQUIRE(length >= 0);
  if (length > 0) {
    REQUIRE(secret != NULL);
  }

  if (dns__tsig_algvalid(algorithm)) {
    if (secret != NULL) {
      isc_buffer_t b;

      isc_buffer_init(&b, secret, length);
      isc_buffer_add(&b, length);
      result = dst_key_frombuffer(
        name, algorithm, DNS_KEYOWNER_ENTITY,
        DNS_KEYPROTO_DNSSEC, dns_rdataclass_in, &b,
        mctx, &dstkey);
      if (result != ISC_R_SUCCESS) {
        return result;
      }
    }
  } else if (length > 0) {
    return DNS_R_BADALG;
  }

  result = dns_tsigkey_createfromkey(name, algorithm, dstkey, false,
             false, NULL, 0, 0, mctx, key);
  if (dstkey != NULL) {
    dst_key_free(&dstkey);
  }
  return result;
}

static void
destroy_tsigkey(dns_tsigkey_t *key) {
  REQUIRE(VALID_TSIGKEY(key));

  key->magic = 0;
  if (key->key != NULL) {
    dst_key_free(&key->key);
  }
  if (key->creator != NULL) {
    dns_name_free(key->creator, key->mctx);
    isc_mem_put(key->mctx, key->creator, sizeof(dns_name_t));
  }
  isc_mem_putanddetach(&key->mctx, key, sizeof(dns_tsigkey_t));
}

#if DNS_TSIG_TRACE
ISC_REFCOUNT_TRACE_IMPL(dns_tsigkey, destroy_tsigkey);
#else
ISC_REFCOUNT_IMPL(dns_tsigkey, destroy_tsigkey);
#endif

void
dns_tsigkey_delete(dns_tsigkey_t *key) {
  REQUIRE(VALID_TSIGKEY(key));

  RWLOCK(&key->ring->lock, isc_rwlocktype_write);
  rm_lru(key);
  rm_hashmap(key);
  RWUNLOCK(&key->ring->lock, isc_rwlocktype_write);
}

isc_result_t
dns_tsig_sign(dns_message_t *msg) {
  dns_tsigkey_t *key = NULL;
  dns_rdata_any_tsig_t tsig, querytsig;
  unsigned char data[128];
  isc_buffer_t databuf, sigbuf;
  isc_buffer_t *dynbuf = NULL;
  dns_name_t *owner = NULL;
  dns_rdata_t *rdata = NULL;
  dns_rdatalist_t *datalist = NULL;
  dns_rdataset_t *dataset = NULL;
  isc_region_t r;
  isc_stdtime_t now;
  isc_mem_t *mctx = NULL;
  dst_context_t *ctx = NULL;
  isc_result_t result;
  unsigned char badtimedata[BADTIMELEN];
  unsigned int sigsize = 0;
  bool response;

  REQUIRE(msg != NULL);
  key = dns_message_gettsigkey(msg);
  REQUIRE(VALID_TSIGKEY(key));

  /*
   * If this is a response, there should be a TSIG in the query with the
   * the exception if this is a TKEY request (see RFC 3645, Section 2.2).
   */
  response = is_response(msg);
  if (response && msg->querytsig == NULL) {
    if (msg->tkey != 1) {
      return DNS_R_EXPECTEDTSIG;
    }
  }

  mctx = msg->mctx;

  now = msg->fuzzing ? msg->fuzztime : isc_stdtime_now();
  tsig = (dns_rdata_any_tsig_t){
    .mctx = mctx,
    .common.rdclass = dns_rdataclass_any,
    .common.rdtype = dns_rdatatype_tsig,
    .timesigned = now + msg->timeadjust,
    .fudge = DNS_TSIG_FUDGE,
    .originalid = msg->id,
    .error = response ? msg->querytsigstatus : dns_rcode_noerror,
  };

  dns_name_init(&tsig.algorithm);
  dns_name_clone(dns_tsigkey_algorithm(key), &tsig.algorithm);

  isc_buffer_init(&databuf, data, sizeof(data));

  if (tsig.error == dns_tsigerror_badtime) {
    isc_buffer_t otherbuf;

    tsig.otherlen = BADTIMELEN;
    tsig.other = badtimedata;
    isc_buffer_init(&otherbuf, tsig.other, tsig.otherlen);
    isc_buffer_putuint48(&otherbuf, tsig.timesigned);
  }

  if ((key->key != NULL) && (tsig.error != dns_tsigerror_badsig) &&
      (tsig.error != dns_tsigerror_badkey))
  {
    unsigned char header[DNS_MESSAGE_HEADERLEN];
    isc_buffer_t headerbuf;
    uint16_t digestbits;
    bool querytsig_ok = false;

    /*
     * If it is a response, we assume that the request MAC
     * has validated at this point. This is why we include a
     * MAC length > 0 in the reply.
     */
    result = dst_context_create(key->key, mctx,
              DNS_LOGCATEGORY_DNSSEC, true, &ctx);
    if (result != ISC_R_SUCCESS) {
      return result;
    }

    /*
     * If this is a response, and if there was a TSIG in
     * the query, digest the request's MAC.
     *
     * (Note: querytsig should be non-NULL for all
     * responses except TKEY responses. Those may be signed
     * with the newly-negotiated TSIG key even if the query
     * wasn't signed.)
     */
    if (response && msg->querytsig != NULL) {
      dns_rdata_t querytsigrdata = DNS_RDATA_INIT;

      INSIST(msg->verified_sig);

      result = dns_rdataset_first(msg->querytsig);
      if (result != ISC_R_SUCCESS) {
        goto cleanup_context;
      }
      dns_rdataset_current(msg->querytsig, &querytsigrdata);
      result = dns_rdata_tostruct(&querytsigrdata, &querytsig,
                NULL);
      if (result != ISC_R_SUCCESS) {
        goto cleanup_context;
      }
      isc_buffer_putuint16(&databuf, querytsig.siglen);
      if (isc_buffer_availablelength(&databuf) <
          querytsig.siglen)
      {
        result = ISC_R_NOSPACE;
        goto cleanup_context;
      }
      isc_buffer_putmem(&databuf, querytsig.signature,
            querytsig.siglen);
      isc_buffer_usedregion(&databuf, &r);
      result = dst_context_adddata(ctx, &r);
      if (result != ISC_R_SUCCESS) {
        goto cleanup_context;
      }
      querytsig_ok = true;
    }

    /*
     * Digest the header.
     */
    isc_buffer_init(&headerbuf, header, sizeof(header));
    dns_message_renderheader(msg, &headerbuf);
    isc_buffer_usedregion(&headerbuf, &r);
    result = dst_context_adddata(ctx, &r);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }

    /*
     * Digest the remainder of the message.
     */
    isc_buffer_usedregion(msg->buffer, &r);
    isc_region_consume(&r, DNS_MESSAGE_HEADERLEN);
    result = dst_context_adddata(ctx, &r);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }

    if (msg->tcp_continuation == 0) {
      /*
       * Digest the name, class, ttl, alg.
       */
      dns_name_toregion(key->name, &r);
      result = dst_context_adddata(ctx, &r);
      if (result != ISC_R_SUCCESS) {
        goto cleanup_context;
      }

      isc_buffer_clear(&databuf);
      isc_buffer_putuint16(&databuf, dns_rdataclass_any);
      isc_buffer_putuint32(&databuf, 0); /* ttl */
      isc_buffer_usedregion(&databuf, &r);
      result = dst_context_adddata(ctx, &r);
      if (result != ISC_R_SUCCESS) {
        goto cleanup_context;
      }

      dns_name_toregion(&tsig.algorithm, &r);
      result = dst_context_adddata(ctx, &r);
      if (result != ISC_R_SUCCESS) {
        goto cleanup_context;
      }
    }
    /* Digest the timesigned and fudge */
    isc_buffer_clear(&databuf);
    if (tsig.error == dns_tsigerror_badtime && querytsig_ok) {
      tsig.timesigned = querytsig.timesigned;
    }
    isc_buffer_putuint48(&databuf, tsig.timesigned);
    isc_buffer_putuint16(&databuf, tsig.fudge);
    isc_buffer_usedregion(&databuf, &r);
    result = dst_context_adddata(ctx, &r);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }

    if (msg->tcp_continuation == 0) {
      /*
       * Digest the error and other data length.
       */
      isc_buffer_clear(&databuf);
      isc_buffer_putuint16(&databuf, tsig.error);
      isc_buffer_putuint16(&databuf, tsig.otherlen);

      isc_buffer_usedregion(&databuf, &r);
      result = dst_context_adddata(ctx, &r);
      if (result != ISC_R_SUCCESS) {
        goto cleanup_context;
      }

      /*
       * Digest other data.
       */
      if (tsig.otherlen > 0) {
        r.length = tsig.otherlen;
        r.base = tsig.other;
        result = dst_context_adddata(ctx, &r);
        if (result != ISC_R_SUCCESS) {
          goto cleanup_context;
        }
      }
    }

    result = dst_key_sigsize(key->key, &sigsize);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }
    tsig.signature = isc_mem_get(mctx, sigsize);

    isc_buffer_init(&sigbuf, tsig.signature, sigsize);
    result = dst_context_sign(ctx, &sigbuf);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_signature;
    }
    dst_context_destroy(&ctx);
    digestbits = dst_key_getbits(key->key);
    if (digestbits != 0) {
      unsigned int bytes = (digestbits + 7) / 8;
      if (querytsig_ok && bytes < querytsig.siglen) {
        bytes = querytsig.siglen;
      }
      if (bytes > isc_buffer_usedlength(&sigbuf)) {
        bytes = isc_buffer_usedlength(&sigbuf);
      }
      tsig.siglen = bytes;
    } else {
      tsig.siglen = isc_buffer_usedlength(&sigbuf);
    }
  } else {
    tsig.siglen = 0;
    tsig.signature = NULL;
  }

  dns_message_gettemprdata(msg, &rdata);
  isc_buffer_allocate(msg->mctx, &dynbuf, 512);
  result = dns_rdata_fromstruct(rdata, dns_rdataclass_any,
              dns_rdatatype_tsig, &tsig, dynbuf);
  if (result != ISC_R_SUCCESS) {
    goto cleanup_dynbuf;
  }

  dns_message_takebuffer(msg, &dynbuf);

  if (tsig.signature != NULL) {
    isc_mem_put(mctx, tsig.signature, sigsize);
  }

  dns_message_gettempname(msg, &owner);
  dns_name_copy(key->name, owner);

  dns_message_gettemprdatalist(msg, &datalist);

  dns_message_gettemprdataset(msg, &dataset);
  datalist->rdclass = dns_rdataclass_any;
  datalist->type = dns_rdatatype_tsig;
  ISC_LIST_APPEND(datalist->rdata, rdata, link);
  dns_rdatalist_tordataset(datalist, dataset);
  msg->tsig = dataset;
  msg->tsigname = owner;

  /* Windows does not like the tsig name being compressed. */
  msg->tsigname->attributes.nocompress = true;

  return ISC_R_SUCCESS;

cleanup_dynbuf:
  isc_buffer_free(&dynbuf);
  dns_message_puttemprdata(msg, &rdata);
cleanup_signature:
  if (tsig.signature != NULL) {
    isc_mem_put(mctx, tsig.signature, sigsize);
  }
cleanup_context:
  if (ctx != NULL) {
    dst_context_destroy(&ctx);
  }
  return result;
}

isc_result_t
dns_tsig_verify(isc_buffer_t *source, dns_message_t *msg,
    dns_tsigkeyring_t *ring1, dns_tsigkeyring_t *ring2) {
  dns_rdata_any_tsig_t tsig, querytsig;
  isc_region_t r, source_r, header_r, sig_r;
  isc_buffer_t databuf;
  unsigned char data[32];
  dns_name_t *keyname = NULL;
  dns_rdata_t rdata = DNS_RDATA_INIT;
  isc_stdtime_t now;
  isc_result_t result;
  dns_tsigkey_t *tsigkey = NULL;
  dst_key_t *key = NULL;
  unsigned char header[DNS_MESSAGE_HEADERLEN];
  dst_context_t *ctx = NULL;
  isc_mem_t *mctx = NULL;
  uint16_t addcount, id;
  unsigned int siglen;
  unsigned int alg;
  bool response;

  REQUIRE(source != NULL);
  REQUIRE(DNS_MESSAGE_VALID(msg));
  tsigkey = dns_message_gettsigkey(msg);
  response = is_response(msg);

  REQUIRE(tsigkey == NULL || VALID_TSIGKEY(tsigkey));

  msg->verify_attempted = 1;
  msg->verified_sig = 0;
  msg->tsigstatus = dns_tsigerror_badsig;

  if (msg->tcp_continuation) {
    if (tsigkey == NULL || msg->querytsig == NULL) {
      return DNS_R_UNEXPECTEDTSIG;
    }
    return tsig_verify_tcp(source, msg);
  }

  /*
   * There should be a TSIG record...
   */
  if (msg->tsig == NULL) {
    return DNS_R_EXPECTEDTSIG;
  }

  /*
   * If this is a response and there's no key or query TSIG, there
   * shouldn't be one on the response.
   */
  if (response && (tsigkey == NULL || msg->querytsig == NULL)) {
    return DNS_R_UNEXPECTEDTSIG;
  }

  mctx = msg->mctx;

  /*
   * If we're here, we know the message is well formed and contains a
   * TSIG record.
   */

  keyname = msg->tsigname;
  result = dns_rdataset_first(msg->tsig);
  if (result != ISC_R_SUCCESS) {
    return result;
  }
  dns_rdataset_current(msg->tsig, &rdata);
  result = dns_rdata_tostruct(&rdata, &tsig, NULL);
  if (result != ISC_R_SUCCESS) {
    return result;
  }
  dns_rdata_reset(&rdata);
  if (response) {
    result = dns_rdataset_first(msg->querytsig);
    if (result != ISC_R_SUCCESS) {
      return result;
    }
    dns_rdataset_current(msg->querytsig, &rdata);
    result = dns_rdata_tostruct(&rdata, &querytsig, NULL);
    if (result != ISC_R_SUCCESS) {
      return result;
    }
  }

  /*
   * Do the key name and algorithm match that of the query?
   */
  if (response &&
      (!dns_name_equal(keyname, tsigkey->name) ||
       !dns_name_equal(&tsig.algorithm, &querytsig.algorithm)))
  {
    msg->tsigstatus = dns_tsigerror_badkey;
    tsig_log(msg->tsigkey, 2,
       "key name and algorithm do not match");
    return DNS_R_TSIGVERIFYFAILURE;
  }

  /*
   * Get the current time.
   */
  if (msg->fuzzing) {
    now = msg->fuzztime;
  } else {
    now = isc_stdtime_now();
  }

  /*
   * Find dns_tsigkey_t based on keyname.
   */
  if (tsigkey == NULL) {
    result = ISC_R_NOTFOUND;
    if (ring1 != NULL) {
      result = dns_tsigkey_find(&tsigkey, keyname,
              &tsig.algorithm, ring1);
    }
    if (result == ISC_R_NOTFOUND && ring2 != NULL) {
      result = dns_tsigkey_find(&tsigkey, keyname,
              &tsig.algorithm, ring2);
    }
    if (result != ISC_R_SUCCESS) {
      msg->tsigstatus = dns_tsigerror_badkey;
      alg = dns__tsig_algfromname(&tsig.algorithm);
      result = dns_tsigkey_create(keyname, alg, NULL, 0, mctx,
                &msg->tsigkey);
      if (result != ISC_R_SUCCESS) {
        return result;
      }
      if (alg == DST_ALG_UNKNOWN) {
        dns_name_clone(&tsig.algorithm,
                 &msg->tsigkey->algname);
      }

      tsig_log(msg->tsigkey, 2, "unknown key");
      return DNS_R_TSIGVERIFYFAILURE;
    }
    msg->tsigkey = tsigkey;
  }

  key = tsigkey->key;

  /*
   * Check digest length.
   */
  alg = dst_key_alg(key);
  result = dst_key_sigsize(key, &siglen);
  if (result != ISC_R_SUCCESS) {
    return result;
  }
  if (dns__tsig_algvalid(alg)) {
    if (tsig.siglen > siglen) {
      tsig_log(msg->tsigkey, 2, "signature length too big");
      return DNS_R_FORMERR;
    }
    if (tsig.siglen > 0 &&
        (tsig.siglen < 10 || tsig.siglen < ((siglen + 1) / 2)))
    {
      tsig_log(msg->tsigkey, 2,
         "signature length below minimum");
      return DNS_R_FORMERR;
    }
  }

  if (tsig.siglen > 0) {
    uint16_t addcount_n;

    sig_r.base = tsig.signature;
    sig_r.length = tsig.siglen;

    result = dst_context_create(key, mctx, DNS_LOGCATEGORY_DNSSEC,
              false, &ctx);
    if (result != ISC_R_SUCCESS) {
      return result;
    }

    if (response) {
      isc_buffer_init(&databuf, data, sizeof(data));
      isc_buffer_putuint16(&databuf, querytsig.siglen);
      isc_buffer_usedregion(&databuf, &r);
      result = dst_context_adddata(ctx, &r);
      if (result != ISC_R_SUCCESS) {
        goto cleanup_context;
      }
      if (querytsig.siglen > 0) {
        r.length = querytsig.siglen;
        r.base = querytsig.signature;
        result = dst_context_adddata(ctx, &r);
        if (result != ISC_R_SUCCESS) {
          goto cleanup_context;
        }
      }
    }

    /*
     * Extract the header.
     */
    isc_buffer_usedregion(source, &r);
    memmove(header, r.base, DNS_MESSAGE_HEADERLEN);
    isc_region_consume(&r, DNS_MESSAGE_HEADERLEN);

    /*
     * Decrement the additional field counter.
     */
    memmove(&addcount, &header[DNS_MESSAGE_HEADERLEN - 2], 2);
    addcount_n = ntohs(addcount);
    addcount = htons((uint16_t)(addcount_n - 1));
    memmove(&header[DNS_MESSAGE_HEADERLEN - 2], &addcount, 2);

    /*
     * Put in the original id.
     */
    id = htons(tsig.originalid);
    memmove(&header[0], &id, 2);

    /*
     * Digest the modified header.
     */
    header_r.base = (unsigned char *)header;
    header_r.length = DNS_MESSAGE_HEADERLEN;
    result = dst_context_adddata(ctx, &header_r);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }

    /*
     * Digest all non-TSIG records.
     */
    isc_buffer_usedregion(source, &source_r);
    r.base = source_r.base + DNS_MESSAGE_HEADERLEN;
    r.length = msg->sigstart - DNS_MESSAGE_HEADERLEN;
    result = dst_context_adddata(ctx, &r);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }

    /*
     * Digest the key name.
     */
    dns_name_toregion(tsigkey->name, &r);
    result = dst_context_adddata(ctx, &r);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }

    isc_buffer_init(&databuf, data, sizeof(data));
    isc_buffer_putuint16(&databuf, tsig.common.rdclass);
    isc_buffer_putuint32(&databuf, msg->tsig->ttl);
    isc_buffer_usedregion(&databuf, &r);
    result = dst_context_adddata(ctx, &r);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }

    /*
     * Digest the key algorithm.
     */
    dns_name_toregion(dns_tsigkey_algorithm(tsigkey), &r);
    result = dst_context_adddata(ctx, &r);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }

    isc_buffer_clear(&databuf);
    isc_buffer_putuint48(&databuf, tsig.timesigned);
    isc_buffer_putuint16(&databuf, tsig.fudge);
    isc_buffer_putuint16(&databuf, tsig.error);
    isc_buffer_putuint16(&databuf, tsig.otherlen);
    isc_buffer_usedregion(&databuf, &r);
    result = dst_context_adddata(ctx, &r);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }

    if (tsig.otherlen > 0) {
      r.base = tsig.other;
      r.length = tsig.otherlen;
      result = dst_context_adddata(ctx, &r);
      if (result != ISC_R_SUCCESS) {
        goto cleanup_context;
      }
    }

    result = dst_context_verify(ctx, &sig_r);
    if (result == DST_R_VERIFYFAILURE) {
      result = DNS_R_TSIGVERIFYFAILURE;
      tsig_log(msg->tsigkey, 2,
         "signature failed to verify(1)");
      goto cleanup_context;
    } else if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }
    msg->verified_sig = 1;
  } else if (!response || (tsig.error != dns_tsigerror_badsig &&
         tsig.error != dns_tsigerror_badkey))
  {
    tsig_log(msg->tsigkey, 2, "signature was empty");
    return DNS_R_TSIGVERIFYFAILURE;
  }

  /*
   * Here at this point, the MAC has been verified. Even if any of
   * the following code returns a TSIG error, the reply will be
   * signed and WILL always include the request MAC in the digest
   * computation.
   */

  /*
   * Is the time ok?
   */
  if (now + msg->timeadjust > tsig.timesigned + tsig.fudge) {
    msg->tsigstatus = dns_tsigerror_badtime;
    tsig_log(msg->tsigkey, 2, "signature has expired");
    result = DNS_R_CLOCKSKEW;
    goto cleanup_context;
  } else if (now + msg->timeadjust < tsig.timesigned - tsig.fudge) {
    msg->tsigstatus = dns_tsigerror_badtime;
    tsig_log(msg->tsigkey, 2, "signature is in the future");
    result = DNS_R_CLOCKSKEW;
    goto cleanup_context;
  }

  if (dns__tsig_algvalid(alg)) {
    uint16_t digestbits = dst_key_getbits(key);

    if (tsig.siglen > 0 && digestbits != 0 &&
        tsig.siglen < ((digestbits + 7) / 8))
    {
      msg->tsigstatus = dns_tsigerror_badtrunc;
      tsig_log(msg->tsigkey, 2,
         "truncated signature length too small");
      result = DNS_R_TSIGVERIFYFAILURE;
      goto cleanup_context;
    }
    if (tsig.siglen > 0 && digestbits == 0 && tsig.siglen < siglen)
    {
      msg->tsigstatus = dns_tsigerror_badtrunc;
      tsig_log(msg->tsigkey, 2, "signature length too small");
      result = DNS_R_TSIGVERIFYFAILURE;
      goto cleanup_context;
    }
  }

  if (response && tsig.error != dns_rcode_noerror) {
    msg->tsigstatus = tsig.error;
    if (tsig.error == dns_tsigerror_badtime) {
      result = DNS_R_CLOCKSKEW;
    } else {
      result = DNS_R_TSIGERRORSET;
    }
    goto cleanup_context;
  }

  msg->tsigstatus = dns_rcode_noerror;
  result = ISC_R_SUCCESS;

cleanup_context:
  if (ctx != NULL) {
    dst_context_destroy(&ctx);
  }

  return result;
}

static isc_result_t
tsig_verify_tcp(isc_buffer_t *source, dns_message_t *msg) {
  dns_rdata_any_tsig_t tsig, querytsig;
  isc_region_t r, source_r, header_r, sig_r;
  isc_buffer_t databuf;
  unsigned char data[32];
  dns_name_t *keyname = NULL;
  dns_rdata_t rdata = DNS_RDATA_INIT;
  isc_stdtime_t now;
  isc_result_t result;
  dns_tsigkey_t *tsigkey = NULL;
  dst_key_t *key = NULL;
  unsigned char header[DNS_MESSAGE_HEADERLEN];
  uint16_t addcount, id;
  bool has_tsig = false;
  isc_mem_t *mctx = NULL;
  unsigned int siglen;
  unsigned int alg;

  REQUIRE(source != NULL);
  REQUIRE(msg != NULL);
  REQUIRE(dns_message_gettsigkey(msg) != NULL);
  REQUIRE(msg->tcp_continuation == 1);
  REQUIRE(msg->querytsig != NULL);

  msg->verified_sig = 0;
  msg->tsigstatus = dns_tsigerror_badsig;

  if (!is_response(msg)) {
    return DNS_R_EXPECTEDRESPONSE;
  }

  mctx = msg->mctx;

  tsigkey = dns_message_gettsigkey(msg);
  key = tsigkey->key;

  /*
   * Extract and parse the previous TSIG
   */
  result = dns_rdataset_first(msg->querytsig);
  if (result != ISC_R_SUCCESS) {
    return result;
  }
  dns_rdataset_current(msg->querytsig, &rdata);
  result = dns_rdata_tostruct(&rdata, &querytsig, NULL);
  if (result != ISC_R_SUCCESS) {
    return result;
  }
  dns_rdata_reset(&rdata);

  /*
   * If there is a TSIG in this message, do some checks.
   */
  if (msg->tsig != NULL) {
    has_tsig = true;

    keyname = msg->tsigname;
    result = dns_rdataset_first(msg->tsig);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_querystruct;
    }
    dns_rdataset_current(msg->tsig, &rdata);
    result = dns_rdata_tostruct(&rdata, &tsig, NULL);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_querystruct;
    }

    /*
     * Do the key name and algorithm match that of the query?
     */
    if (!dns_name_equal(keyname, tsigkey->name) ||
        !dns_name_equal(&tsig.algorithm, &querytsig.algorithm))
    {
      msg->tsigstatus = dns_tsigerror_badkey;
      result = DNS_R_TSIGVERIFYFAILURE;
      tsig_log(msg->tsigkey, 2,
         "key name and algorithm do not match");
      goto cleanup_querystruct;
    }

    /*
     * Check digest length.
     */
    alg = dst_key_alg(key);
    result = dst_key_sigsize(key, &siglen);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_querystruct;
    }
    if (dns__tsig_algvalid(alg)) {
      if (tsig.siglen > siglen) {
        tsig_log(tsigkey, 2,
           "signature length too big");
        result = DNS_R_FORMERR;
        goto cleanup_querystruct;
      }
      if (tsig.siglen > 0 &&
          (tsig.siglen < 10 ||
           tsig.siglen < ((siglen + 1) / 2)))
      {
        tsig_log(tsigkey, 2,
           "signature length below minimum");
        result = DNS_R_FORMERR;
        goto cleanup_querystruct;
      }
    }
  }

  if (msg->tsigctx == NULL) {
    result = dst_context_create(key, mctx, DNS_LOGCATEGORY_DNSSEC,
              false, &msg->tsigctx);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_querystruct;
    }

    /*
     * Digest the length of the query signature
     */
    isc_buffer_init(&databuf, data, sizeof(data));
    isc_buffer_putuint16(&databuf, querytsig.siglen);
    isc_buffer_usedregion(&databuf, &r);
    result = dst_context_adddata(msg->tsigctx, &r);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }

    /*
     * Digest the data of the query signature
     */
    if (querytsig.siglen > 0) {
      r.length = querytsig.siglen;
      r.base = querytsig.signature;
      result = dst_context_adddata(msg->tsigctx, &r);
      if (result != ISC_R_SUCCESS) {
        goto cleanup_context;
      }
    }
  }

  /*
   * Extract the header.
   */
  isc_buffer_usedregion(source, &r);
  memmove(header, r.base, DNS_MESSAGE_HEADERLEN);
  isc_region_consume(&r, DNS_MESSAGE_HEADERLEN);

  /*
   * Decrement the additional field counter if necessary.
   */
  if (has_tsig) {
    uint16_t addcount_n;

    memmove(&addcount, &header[DNS_MESSAGE_HEADERLEN - 2], 2);
    addcount_n = ntohs(addcount);
    addcount = htons((uint16_t)(addcount_n - 1));
    memmove(&header[DNS_MESSAGE_HEADERLEN - 2], &addcount, 2);

    /*
     * Put in the original id.
     *
     * XXX Can TCP transfers be forwarded?  How would that
     * work?
     */
    id = htons(tsig.originalid);
    memmove(&header[0], &id, 2);
  }

  /*
   * Digest the modified header.
   */
  header_r.base = (unsigned char *)header;
  header_r.length = DNS_MESSAGE_HEADERLEN;
  result = dst_context_adddata(msg->tsigctx, &header_r);
  if (result != ISC_R_SUCCESS) {
    goto cleanup_context;
  }

  /*
   * Digest all non-TSIG records.
   */
  isc_buffer_usedregion(source, &source_r);
  r.base = source_r.base + DNS_MESSAGE_HEADERLEN;
  if (has_tsig) {
    r.length = msg->sigstart - DNS_MESSAGE_HEADERLEN;
  } else {
    r.length = source_r.length - DNS_MESSAGE_HEADERLEN;
  }
  result = dst_context_adddata(msg->tsigctx, &r);
  if (result != ISC_R_SUCCESS) {
    goto cleanup_context;
  }

  /*
   * Digest the time signed and fudge.
   */
  if (has_tsig) {
    isc_buffer_init(&databuf, data, sizeof(data));
    isc_buffer_putuint48(&databuf, tsig.timesigned);
    isc_buffer_putuint16(&databuf, tsig.fudge);
    isc_buffer_usedregion(&databuf, &r);
    result = dst_context_adddata(msg->tsigctx, &r);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }

    sig_r.base = tsig.signature;
    sig_r.length = tsig.siglen;
    if (tsig.siglen == 0) {
      if (tsig.error != dns_rcode_noerror) {
        msg->tsigstatus = tsig.error;
        if (tsig.error == dns_tsigerror_badtime) {
          result = DNS_R_CLOCKSKEW;
        } else {
          result = DNS_R_TSIGERRORSET;
        }
      } else {
        tsig_log(msg->tsigkey, 2, "signature is empty");
        result = DNS_R_TSIGVERIFYFAILURE;
      }
      goto cleanup_context;
    }

    result = dst_context_verify(msg->tsigctx, &sig_r);
    if (result == DST_R_VERIFYFAILURE) {
      tsig_log(msg->tsigkey, 2,
         "signature failed to verify(2)");
      result = DNS_R_TSIGVERIFYFAILURE;
      goto cleanup_context;
    } else if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }
    msg->verified_sig = 1;

    /*
     * Here at this point, the MAC has been verified. Even
     * if any of the following code returns a TSIG error,
     * the reply will be signed and WILL always include the
     * request MAC in the digest computation.
     */

    /*
     * Is the time ok?
     */
    if (msg->fuzzing) {
      now = msg->fuzztime;
    } else {
      now = isc_stdtime_now();
    }

    if (now + msg->timeadjust > tsig.timesigned + tsig.fudge) {
      msg->tsigstatus = dns_tsigerror_badtime;
      tsig_log(msg->tsigkey, 2, "signature has expired");
      result = DNS_R_CLOCKSKEW;
      goto cleanup_context;
    } else if (now + msg->timeadjust < tsig.timesigned - tsig.fudge)
    {
      msg->tsigstatus = dns_tsigerror_badtime;
      tsig_log(msg->tsigkey, 2, "signature is in the future");
      result = DNS_R_CLOCKSKEW;
      goto cleanup_context;
    }

    alg = dst_key_alg(key);
    result = dst_key_sigsize(key, &siglen);
    if (result != ISC_R_SUCCESS) {
      goto cleanup_context;
    }
    if (dns__tsig_algvalid(alg)) {
      uint16_t digestbits = dst_key_getbits(key);

      if (tsig.siglen > 0 && digestbits != 0 &&
          tsig.siglen < ((digestbits + 7) / 8))
      {
        msg->tsigstatus = dns_tsigerror_badtrunc;
        tsig_log(msg->tsigkey, 2,
           "truncated signature length "
           "too small");
        result = DNS_R_TSIGVERIFYFAILURE;
        goto cleanup_context;
      }
      if (tsig.siglen > 0 && digestbits == 0 &&
          tsig.siglen < siglen)
      {
        msg->tsigstatus = dns_tsigerror_badtrunc;
        tsig_log(msg->tsigkey, 2,
           "signature length too small");
        result = DNS_R_TSIGVERIFYFAILURE;
        goto cleanup_context;
      }
    }

    if (tsig.error != dns_rcode_noerror) {
      msg->tsigstatus = tsig.error;
      if (tsig.error == dns_tsigerror_badtime) {
        result = DNS_R_CLOCKSKEW;
      } else {
        result = DNS_R_TSIGERRORSET;
      }
      goto cleanup_context;
    }
  }

  msg->tsigstatus = dns_rcode_noerror;
  result = ISC_R_SUCCESS;

cleanup_context:
  /*
   * Except in error conditions, don't destroy the DST context
   * for unsigned messages; it is a running sum till the next
   * TSIG signed message.
   */
  if ((result != ISC_R_SUCCESS || has_tsig) && msg->tsigctx != NULL) {
    dst_context_destroy(&msg->tsigctx);
  }

cleanup_querystruct:
  dns_rdata_freestruct(&querytsig);

  return result;
}

isc_result_t
dns_tsigkey_find(dns_tsigkey_t **tsigkey, const dns_name_t *name,
     const dns_name_t *algorithm, dns_tsigkeyring_t *ring) {
  dns_tsigkey_t *key = NULL;
  isc_result_t result;
  isc_rwlocktype_t locktype = isc_rwlocktype_read;
  isc_stdtime_t now = isc_stdtime_now();

  REQUIRE(name != NULL);
  REQUIRE(VALID_TSIGKEYRING(ring));
  REQUIRE(tsigkey != NULL && *tsigkey == NULL);

again:
  RWLOCK(&ring->lock, locktype);
  result = isc_hashmap_find(ring->keys, dns_name_hash(name), tkey_match,
          name, (void **)&key);
  if (result == ISC_R_NOTFOUND) {
    RWUNLOCK(&ring->lock, locktype);
    return result;
  }

  if (algorithm != NULL && key->alg != dns__tsig_algfromname(algorithm)) {
    RWUNLOCK(&ring->lock, locktype);
    return ISC_R_NOTFOUND;
  }
  if (key->inception != key->expire && isc_serial_lt(key->expire, now)) {
    /*
     * The key has expired.
     */
    if (locktype == isc_rwlocktype_read) {
      RWUNLOCK(&ring->lock, locktype);
      locktype = isc_rwlocktype_write;
      key = NULL;
      goto again;
    }
    rm_lru(key);
    rm_hashmap(key);
    RWUNLOCK(&ring->lock, locktype);
    return ISC_R_NOTFOUND;
  }
  dns_tsigkey_ref(key);
  RWUNLOCK(&ring->lock, locktype);
  adjust_lru(key);
  *tsigkey = key;
  return ISC_R_SUCCESS;
}

const dns_name_t *
dns_tsigkey_algorithm(dns_tsigkey_t *tkey) {
  REQUIRE(VALID_TSIGKEY(tkey));

  switch (tkey->alg) {
  case DST_ALG_HMACMD5:
    return dns_tsig_hmacmd5_name;
  case DST_ALG_HMACSHA1:
    return dns_tsig_hmacsha1_name;
  case DST_ALG_HMACSHA224:
    return dns_tsig_hmacsha224_name;
  case DST_ALG_HMACSHA256:
    return dns_tsig_hmacsha256_name;
  case DST_ALG_HMACSHA384:
    return dns_tsig_hmacsha384_name;
  case DST_ALG_HMACSHA512:
    return dns_tsig_hmacsha512_name;
  case DST_ALG_GSSAPI:
    return dns_tsig_gssapi_name;

  case DST_ALG_UNKNOWN:
    /*
     * If the tsigkey object was created with an
     * unknown algorithm, then we cloned
     * the algorithm name here.
     */
    return &tkey->algname;

  default:
    UNREACHABLE();
  }
}

void
dns_tsigkeyring_create(isc_mem_t *mctx, dns_tsigkeyring_t **ringp) {
  dns_tsigkeyring_t *ring = NULL;

  REQUIRE(mctx != NULL);
  REQUIRE(ringp != NULL && *ringp == NULL);

  ring = isc_mem_get(mctx, sizeof(dns_tsigkeyring_t));
  *ring = (dns_tsigkeyring_t){
    .lru = ISC_LIST_INITIALIZER,
  };

  isc_hashmap_create(mctx, 12, &ring->keys);
  isc_rwlock_init(&ring->lock);
  isc_mem_attach(mctx, &ring->mctx);
  isc_refcount_init(&ring->references, 1);
  ring->magic = TSIGKEYRING_MAGIC;

  *ringp = ring;
}

isc_result_t
dns_tsigkeyring_add(dns_tsigkeyring_t *ring, dns_tsigkey_t *tkey) {
  isc_result_t result;

  REQUIRE(VALID_TSIGKEY(tkey));
  REQUIRE(VALID_TSIGKEYRING(ring));
  REQUIRE(tkey->ring == NULL);

  RWLOCK(&ring->lock, isc_rwlocktype_write);
  result = isc_hashmap_add(ring->keys, dns_name_hash(tkey->name),
         tkey_match, tkey->name, tkey, NULL);
  if (result == ISC_R_SUCCESS) {
    dns_tsigkey_ref(tkey);
    tkey->ring = ring;

    /*
     * If this is a TKEY-generated key, add it to the LRU list,
     * and if we've exceeded the quota for generated keys,
     * remove the least recently used one from the both the
     * list and the RBT.
     */
    if (tkey->generated) {
      ISC_LIST_APPEND(ring->lru, tkey, link);
      dns_tsigkey_ref(tkey);
      if (ring->generated++ > DNS_TSIG_MAXGENERATEDKEYS) {
        dns_tsigkey_t *key = ISC_LIST_HEAD(ring->lru);
        rm_lru(key);
        rm_hashmap(key);
      }
    }

    tkey->ring = ring;
  }
  RWUNLOCK(&ring->lock, isc_rwlocktype_write);

  return result;
}

void
dns_tsigkeyring_restore(dns_tsigkeyring_t *ring, FILE *fp) {
  isc_stdtime_t now = isc_stdtime_now();
  isc_result_t result;

  do {
    result = restore_key(ring, now, fp);
    if (result == ISC_R_NOMORE) {
      return;
    }
    if (result == DNS_R_BADALG || result == DNS_R_EXPIRED) {
      result = ISC_R_SUCCESS;
    }
  } while (result == ISC_R_SUCCESS);
}

Coverage Report

Created: 2025-11-11 07:03