lib/dns/tkey.c

	tkey.c revision 9b0c4bf7003db929fe00a345fc96fb97677d29e0
/*
 * Copyright (C) 1999-2001  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
 * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * $Id: tkey.c,v 1.60 2001/01/11 04:23:39 bwelling Exp $
 */

#include <config.h>

#include <isc/buffer.h>
#include <isc/entropy.h>
#include <isc/md5.h>
#include <isc/mem.h>
#include <isc/string.h>
#include <isc/util.h>

#include <dns/dnssec.h>
#include <dns/keyvalues.h>
#include <dns/log.h>
#include <dns/message.h>
#include <dns/name.h>
#include <dns/rdata.h>
#include <dns/rdatalist.h>
#include <dns/rdataset.h>
#include <dns/rdatastruct.h>
#include <dns/result.h>
#include <dns/tkey.h>
#include <dns/tsig.h>

#include <dst/dst.h>
#include <dst/gssapi.h>

#define TKEY_RANDOM_AMOUNT 16

#define RETERR(x) do { \
    result = (x); \
    if (result != ISC_R_SUCCESS) \
        goto failure; \
    } while (0)

static void
tkey_log(const char *fmt, ...) {
    va_list ap;

    va_start(ap, fmt);
    isc_log_vwrite(dns_lctx, DNS_LOGCATEGORY_GENERAL,
               DNS_LOGMODULE_REQUEST, ISC_LOG_DEBUG(4), fmt, ap);
    va_end(ap);
}

isc_result_t
dns_tkeyctx_create(isc_mem_t *mctx, isc_entropy_t *ectx, dns_tkeyctx_t **tctxp)
{
    dns_tkeyctx_t *tctx;

    REQUIRE(mctx != NULL);
    REQUIRE(ectx != NULL);
    REQUIRE(tctxp != NULL && *tctxp == NULL);

    tctx = isc_mem_get(mctx, sizeof(dns_tkeyctx_t));
    if (tctx == NULL)
        return (ISC_R_NOMEMORY);
    tctx->mctx = NULL;
    isc_mem_attach(mctx, &tctx->mctx);
    tctx->ectx = NULL;
    isc_entropy_attach(ectx, &tctx->ectx);
    tctx->dhkey = NULL;
    tctx->domain = NULL;
    tctx->gsscred = NULL;

    *tctxp = tctx;
    return (ISC_R_SUCCESS);
}

void
dns_tkeyctx_destroy(dns_tkeyctx_t **tctxp) {
    isc_mem_t *mctx;
    dns_tkeyctx_t *tctx;

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

    tctx = *tctxp;
    mctx = tctx->mctx;

    if (tctx->dhkey != NULL)
        dst_key_free(&tctx->dhkey);
    if (tctx->domain != NULL) {
        if (dns_name_dynamic(tctx->domain))
            dns_name_free(tctx->domain, mctx);
        isc_mem_put(mctx, tctx->domain, sizeof(dns_name_t));
    }
    isc_entropy_detach(&tctx->ectx);
    isc_mem_put(mctx, tctx, sizeof(dns_tkeyctx_t));
    isc_mem_detach(&mctx);
    *tctxp = NULL;
}

static isc_result_t
add_rdata_to_list(dns_message_t *msg, dns_name_t *name, dns_rdata_t *rdata,
        isc_uint32_t ttl, dns_namelist_t *namelist)
{
    isc_result_t result;
    isc_region_t r, newr;
    dns_rdata_t *newrdata = NULL;
    dns_name_t *newname = NULL;
    dns_rdatalist_t *newlist = NULL;
    dns_rdataset_t *newset = NULL;
    isc_buffer_t *tmprdatabuf = NULL;

    RETERR(dns_message_gettemprdata(msg, &newrdata));

    dns_rdata_toregion(rdata, &r);
    RETERR(isc_buffer_allocate(msg->mctx, &tmprdatabuf, r.length));
    isc_buffer_availableregion(tmprdatabuf, &newr);
    memcpy(newr.base, r.base, r.length);
    dns_rdata_fromregion(newrdata, rdata->rdclass, rdata->type, &newr);
    dns_message_takebuffer(msg, &tmprdatabuf);

    RETERR(dns_message_gettempname(msg, &newname));
    dns_name_init(newname, NULL);
    RETERR(dns_name_dup(name, msg->mctx, newname));

    RETERR(dns_message_gettemprdatalist(msg, &newlist));
    newlist->rdclass = newrdata->rdclass;
    newlist->type = newrdata->type;
    newlist->covers = 0;
    newlist->ttl = ttl;
    ISC_LIST_INIT(newlist->rdata);
    ISC_LIST_APPEND(newlist->rdata, newrdata, link);

    RETERR(dns_message_gettemprdataset(msg, &newset));
    dns_rdataset_init(newset);
    RETERR(dns_rdatalist_tordataset(newlist, newset));

    ISC_LIST_INIT(newname->list);
    ISC_LIST_APPEND(newname->list, newset, link);

    ISC_LIST_APPEND(*namelist, newname, link);

    return (ISC_R_SUCCESS);

 failure:
    if (newrdata != NULL) {
        if (ISC_LINK_LINKED(newrdata, link))
            ISC_LIST_UNLINK(newlist->rdata, newrdata, link);
        dns_message_puttemprdata(msg, &newrdata);
    }
    if (newname != NULL)
        dns_message_puttempname(msg, &newname);
    if (newset != NULL) {
        dns_rdataset_disassociate(newset);
        dns_message_puttemprdataset(msg, &newset);
    }
    if (newlist != NULL)
        dns_message_puttemprdatalist(msg, &newlist);
    return (result);
}

static void
free_namelist(dns_message_t *msg, dns_namelist_t *namelist) {
    dns_name_t *name;
    dns_rdataset_t *set;

    while (!ISC_LIST_EMPTY(*namelist)) {
        name = ISC_LIST_HEAD(*namelist);
        ISC_LIST_UNLINK(*namelist, name, link);
        while (!ISC_LIST_EMPTY(name->list)) {
            set = ISC_LIST_HEAD(name->list);
            ISC_LIST_UNLINK(name->list, set, link);
            dns_message_puttemprdataset(msg, &set);
        }
        dns_message_puttempname(msg, &name);
    }
}

static isc_result_t
compute_secret(isc_buffer_t *shared, isc_region_t *queryrandomness,
           isc_region_t *serverrandomness, isc_buffer_t *secret)
{
    isc_md5_t md5ctx;
    isc_region_t r, r2;
    unsigned char digests[32];
    unsigned int i;

    isc_buffer_usedregion(shared, &r);

    /*
     * MD5 ( query data | DH value ).
     */
    isc_md5_init(&md5ctx);
    isc_md5_update(&md5ctx, queryrandomness->base, queryrandomness->length);
    isc_md5_update(&md5ctx, r.base, r.length);
    isc_md5_final(&md5ctx, digests);

    /*
     * MD5 ( server data | DH value ).
     */
    isc_md5_init(&md5ctx);
    isc_md5_update(&md5ctx, serverrandomness->base,
               serverrandomness->length);
    isc_md5_update(&md5ctx, r.base, r.length);
    isc_md5_final(&md5ctx, &digests[ISC_MD5_DIGESTLENGTH]);

    /*
     * XOR ( DH value, MD5-1 | MD5-2).
     */
    isc_buffer_availableregion(secret, &r);
    isc_buffer_usedregion(shared, &r2);
    if (r.length < sizeof(digests) || r.length < r2.length)
        return (ISC_R_NOSPACE);
    if (r2.length > sizeof(digests)) {
        memcpy(r.base, r2.base, r2.length);
        for (i = 0; i < sizeof(digests); i++)
            r.base[i] ^= digests[i];
        isc_buffer_add(secret, r2.length);
    }
    else {
        memcpy(r.base, digests, sizeof(digests));
        for (i = 0; i < r2.length; i++)
            r.base[i] ^= r2.base[i];
        isc_buffer_add(secret, sizeof(digests));
    }
    return (ISC_R_SUCCESS);

}

static isc_result_t
process_dhtkey(dns_message_t *msg, dns_name_t *signer, dns_name_t *name,
           dns_rdata_tkey_t *tkeyin, dns_tkeyctx_t *tctx,
           dns_rdata_tkey_t *tkeyout,
           dns_tsig_keyring_t *ring, dns_namelist_t *namelist)
{
    isc_result_t result = ISC_R_SUCCESS;
    dns_name_t *keyname, ourname;
    dns_rdataset_t *keyset;
    dns_rdata_t keyrdata = DNS_RDATA_INIT, ourkeyrdata = DNS_RDATA_INIT;
    isc_boolean_t found_key = ISC_FALSE, found_incompatible = ISC_FALSE;
    dst_key_t *pubkey = NULL;
    isc_buffer_t ourkeybuf, *shared = NULL;
    isc_region_t r, r2, ourkeyr;
    isc_uint32_t ourttl;
    unsigned char keydata[DST_KEY_MAXSIZE];
    unsigned int sharedsize;
    isc_buffer_t secret;
    unsigned char *randomdata = NULL, secretdata[256];
    isc_stdtime_t now;

    if (tctx->dhkey == NULL) {
        tkey_log("process_dhtkey: tkey-dhkey not defined");
        tkeyout->error = dns_tsigerror_badalg;
        return (DNS_R_REFUSED);
    }

    if (!dns_name_equal(&tkeyin->algorithm, DNS_TSIG_HMACMD5_NAME)) {
        tkey_log("process_dhtkey: algorithms other than "
             "hmac-md5 are not supported");
        tkeyout->error = dns_tsigerror_badalg;
        return (ISC_R_SUCCESS);
    }

    /*
     * Look for a DH KEY record that will work with ours.
     */
    result = dns_message_firstname(msg, DNS_SECTION_ADDITIONAL);
    while (result == ISC_R_SUCCESS) {
        keyname = NULL;
        dns_message_currentname(msg, DNS_SECTION_ADDITIONAL, &keyname);
        keyset = NULL;
        result = dns_message_findtype(keyname, dns_rdatatype_key, 0,
                          &keyset);
        if (result == ISC_R_SUCCESS) {
            result = dns_rdataset_first(keyset);
            while (result == ISC_R_SUCCESS) {
                dns_rdataset_current(keyset, &keyrdata);
                pubkey = NULL;
                result = dns_dnssec_keyfromrdata(keyname,
                                 &keyrdata,
                                 msg->mctx,
                                 &pubkey);
                if (result != ISC_R_SUCCESS) {
                    result = dns_rdataset_next(keyset);
                    continue;
                }
                if (dst_key_alg(pubkey) == DNS_KEYALG_DH) {
                    if (dst_key_paramcompare(pubkey,
                        tctx->dhkey))
                    {
                        found_key = ISC_TRUE;
                        goto got_key;
                    }
                    else
                        found_incompatible = ISC_TRUE;
                }
                dst_key_free(&pubkey);
                result = dns_rdataset_next(keyset);
            }
        }
        result = dns_message_nextname(msg, DNS_SECTION_ADDITIONAL);
    }

 got_key:
    if (!found_key) {
        if (found_incompatible) {
            tkey_log("process_dhtkey: found an incompatible key");
            tkeyout->error = dns_tsigerror_badkey;
            return (ISC_R_SUCCESS);
        } else
            tkey_log("process_dhtkey: failed to find a key");
        return (DNS_R_FORMERR);
    }

    RETERR(add_rdata_to_list(msg, keyname, &keyrdata, keyset->ttl,
                 namelist));

    isc_buffer_init(&ourkeybuf, keydata, sizeof(keydata));
    RETERR(dst_key_todns(tctx->dhkey, &ourkeybuf));
    isc_buffer_usedregion(&ourkeybuf, &ourkeyr);
    dns_rdata_fromregion(&ourkeyrdata, dns_rdataclass_any,
                 dns_rdatatype_key, &ourkeyr);


    dns_name_init(&ourname, NULL);
    dns_name_clone(dst_key_name(tctx->dhkey), &ourname);
    ourttl = 0;
#if 0
    /*
     * Not sure how to do this without a view...
     */
    db = NULL;
    result = dns_dbtable_find(client->view->dbtable, &ourname, 0, &db);
    if (result == ISC_R_SUCCESS) {
        dns_rdataset_t set;
        dns_fixedname_t foundname;

        dns_rdataset_init(&set);
        dns_fixedname_init(&foundname);
        result = dns_db_find(db, &ourname, NULL, dns_rdatatype_key,
                     DNS_DBFIND_NOWILD, 0, NULL,
                     dns_fixedname_name(&foundname),
                     &set, NULL);
        if (result == ISC_R_SUCCESS) {
            ourttl = set.ttl;
            dns_rdataset_disassociate(&set);
        }
    }
#endif
    RETERR(add_rdata_to_list(msg, &ourname, &ourkeyrdata, ourttl,
                 namelist));

    RETERR(dst_key_secretsize(tctx->dhkey, &sharedsize));
    RETERR(isc_buffer_allocate(msg->mctx, &shared, sharedsize));

    result = dst_key_computesecret(pubkey, tctx->dhkey, shared);
    if (result != ISC_R_SUCCESS) {
        tkey_log("process_dhtkey: failed to compute shared secret: %s",
             isc_result_totext(result));
        goto failure;
    }

    isc_buffer_init(&secret, secretdata, sizeof(secretdata));

    randomdata = isc_mem_get(tkeyout->mctx, TKEY_RANDOM_AMOUNT);
    if (randomdata == NULL) {
        result = ISC_R_NOMEMORY;
        goto failure;
    }
    result = isc_entropy_getdata(tctx->ectx, randomdata,
                     TKEY_RANDOM_AMOUNT, NULL, 0);
    if (result != ISC_R_SUCCESS) {
        tkey_log("process_dhtkey: failed to obtain entropy: %s",
             isc_result_totext(result));
        goto failure;
    }

    r.base = randomdata;
    r.length = TKEY_RANDOM_AMOUNT;
    r2.base = tkeyin->key;
    r2.length = tkeyin->keylen;
    RETERR(compute_secret(shared, &r2, &r, &secret));

    dst_key_free(&pubkey);
    isc_buffer_usedregion(&secret, &r);
    result = dns_tsigkey_create(name, &tkeyin->algorithm, r.base, r.length,
                    ISC_TRUE, signer, tkeyin->inception,
                    tkeyin->expire, msg->mctx, ring, NULL);
    isc_buffer_free(&shared);
    shared = NULL;
    if (result == ISC_R_NOTFOUND) {
        tkeyout->error = dns_tsigerror_badalg;
        return (ISC_R_SUCCESS);
    }
    if (result != ISC_R_SUCCESS)
        goto failure;

    /* This key is good for a long time */
    isc_stdtime_get(&now);
    tkeyout->inception = tkeyin->inception;
    tkeyout->expire = tkeyin->expire;

    tkeyout->key = randomdata;
    tkeyout->keylen = TKEY_RANDOM_AMOUNT;

    return (ISC_R_SUCCESS);

 failure:
    if (!ISC_LIST_EMPTY(*namelist)) {
        dns_name_t *tname = ISC_LIST_HEAD(*namelist);
        while (tname != NULL) {
            dns_name_t *next = ISC_LIST_NEXT(tname, link);
            dns_rdataset_t *tset;

            ISC_LIST_UNLINK(*namelist, tname, link);
            tset = ISC_LIST_HEAD(tname->list);
            dns_rdataset_disassociate(tset);
            dns_message_puttemprdataset(msg, &tset);
            dns_message_puttempname(msg, &tname);
            tname = next;
        }
    }
    if (shared != NULL)
        isc_buffer_free(&shared);
    return (result);
}

static isc_result_t
process_gsstkey(dns_message_t *msg, dns_name_t *signer, dns_name_t *name,
        dns_rdata_tkey_t *tkeyin, dns_tkeyctx_t *tctx,
        dns_rdata_tkey_t *tkeyout,
        dns_tsig_keyring_t *ring, dns_namelist_t *namelist)
{
    isc_result_t result = ISC_R_SUCCESS;
    dst_key_t *dstkey = NULL;
    void *gssctx = NULL;
    isc_stdtime_t now;
    isc_region_t intoken;
    unsigned char array[1024];
    isc_buffer_t outtoken;

    UNUSED(namelist);

    if (tctx->gsscred == NULL)
        return (ISC_R_NOPERM);

    if (!dns_name_equal(&tkeyin->algorithm, DNS_TSIG_GSSAPI_NAME) &&
        !dns_name_equal(&tkeyin->algorithm, DNS_TSIG_GSSAPIMS_NAME)) {
        tkeyout->error = dns_tsigerror_badalg;
        return (ISC_R_SUCCESS);
    }

    intoken.base = tkeyin->key;
    intoken.length = tkeyin->keylen;

    isc_buffer_init(&outtoken, array, sizeof(array));
    RETERR(dst_gssapi_acceptctx(name, tctx->gsscred, &intoken,
                    &outtoken, &gssctx));

    dstkey = NULL;
    RETERR(dst_key_fromgssapi(name, gssctx, msg->mctx, &dstkey));

    result = dns_tsigkey_createfromkey(name, &tkeyin->algorithm,
                       dstkey, ISC_TRUE, signer,
                       tkeyin->inception, tkeyin->expire,
                       msg->mctx, ring, NULL);
    if (result != ISC_R_SUCCESS)
        goto failure;

    if (result == ISC_R_NOTFOUND) {
        tkeyout->error = dns_tsigerror_badalg;
        return (ISC_R_SUCCESS);
    }
    if (result != ISC_R_SUCCESS)
        goto failure;

    /* This key is good for a long time */
    isc_stdtime_get(&now);
    tkeyout->inception = tkeyin->inception;
    tkeyout->expire = tkeyin->expire;

    tkeyout->key = isc_mem_get(msg->mctx,
                   isc_buffer_usedlength(&outtoken));
    if (tkeyout->key == NULL) {
        result = ISC_R_NOMEMORY;
        goto failure;
    }
    tkeyout->keylen = isc_buffer_usedlength(&outtoken);
    memcpy(tkeyout->key, isc_buffer_base(&outtoken), tkeyout->keylen);

    return (ISC_R_SUCCESS);

 failure:
    if (dstkey != NULL)
        dst_key_free(&dstkey);

    return (result);
}

static isc_result_t
process_deletetkey(dns_message_t *msg, dns_name_t *signer, dns_name_t *name,
           dns_rdata_tkey_t *tkeyin,
           dns_rdata_tkey_t *tkeyout,
           dns_tsig_keyring_t *ring,
           dns_namelist_t *namelist)
{
    isc_result_t result;
    dns_tsigkey_t *tsigkey = NULL;
    dns_name_t *identity;

    UNUSED(msg);
    UNUSED(tkeyout);
    UNUSED(namelist);

    result = dns_tsigkey_find(&tsigkey, name, &tkeyin->algorithm, ring);
    if (result != ISC_R_SUCCESS)
        tkeyout->error = dns_tsigerror_badname;

    /*
     * Only allow a delete if the identity that created the key is the
     * same as the identity that signed the message.
     */
    identity = dns_tsigkey_identity(tsigkey);
    if (identity == NULL || !dns_name_equal(identity, signer))
        return (DNS_R_REFUSED);

    /*
     * Set the key to be deleted when no references are left.  If the key
     * was not generated with TKEY and is in the config file, it may be
     * reloaded later.
     */
    dns_tsigkey_setdeleted(tsigkey);
    /* Release the reference */
    dns_tsigkey_detach(&tsigkey);

    return (ISC_R_SUCCESS);
}

isc_result_t
dns_tkey_processquery(dns_message_t *msg, dns_tkeyctx_t *tctx,
              dns_tsig_keyring_t *ring)
{
    isc_result_t result = ISC_R_SUCCESS;
    dns_rdata_tkey_t tkeyin, tkeyout;
    dns_name_t *qname, *name, *keyname, tempkeyname, *signer, tsigner;
    dns_rdataset_t *tkeyset;
    dns_rdata_t tkeyrdata = DNS_RDATA_INIT, *rdata = NULL;
    isc_buffer_t *dynbuf = NULL;
    dns_namelist_t namelist;
    isc_boolean_t freealg = ISC_FALSE;

    REQUIRE(msg != NULL);
    REQUIRE(tctx != NULL);
    REQUIRE(ring != NULL);

    /*
     * Need to do this to determine if this should be freed later.
     */
    memset(&tkeyin, 0, sizeof(dns_rdata_tkey_t));

    /*
     * Interpret the question section.
     */
    result = dns_message_firstname(msg, DNS_SECTION_QUESTION);
    if (result != ISC_R_SUCCESS)
        return (DNS_R_FORMERR);

    qname = NULL;
    dns_message_currentname(msg, DNS_SECTION_QUESTION, &qname);

    /*
     * Look for a TKEY record that matches the question.
     */
    tkeyset = NULL;
    name = NULL;
    result = dns_message_findname(msg, DNS_SECTION_ADDITIONAL, qname,
                      dns_rdatatype_tkey, 0, &name, &tkeyset);
    if (result != ISC_R_SUCCESS) {
        /*
         * Try the answer section, since that's where Win2000
         * puts it.
         */
        if (dns_message_findname(msg, DNS_SECTION_ANSWER, qname,
                     dns_rdatatype_tkey, 0, &name,
                     &tkeyset) != ISC_R_SUCCESS)
        {
            result = DNS_R_FORMERR;
            tkey_log("dns_tkey_processquery: couldn't find a TKEY "
                 "matching the question");
            goto failure;
        }
    }
    result = dns_rdataset_first(tkeyset);
    if (result != ISC_R_SUCCESS) {
        result = DNS_R_FORMERR;
        goto failure;
    }
    dns_rdataset_current(tkeyset, &tkeyrdata);

    RETERR(dns_rdata_tostruct(&tkeyrdata, &tkeyin, NULL));

    if (tkeyin.error != dns_rcode_noerror) {
        result = DNS_R_FORMERR;
        goto failure;
    }

    /*
     * Before we go any farther, verify that the message was signed.
     * GSSAPI TKEY doesn't require a signature, the rest do.
     */
    dns_name_init(&tsigner, NULL);
    result = dns_message_signer(msg, &tsigner);
    if (result != ISC_R_SUCCESS) {
        if (tkeyin.mode == DNS_TKEYMODE_GSSAPI &&
            result == ISC_R_NOTFOUND)
               signer = NULL;
        else {
            tkey_log("dns_tkey_processquery: query was not "
                 "properly signed - rejecting");
            result = DNS_R_FORMERR;
            goto failure;
        }
    } else
        signer = &tsigner;

    ISC_LIST_INIT(namelist);

    tkeyout.common.rdclass = tkeyin.common.rdclass;
    tkeyout.common.rdtype = tkeyin.common.rdtype;
    ISC_LINK_INIT(&tkeyout.common, link);
    tkeyout.mctx = msg->mctx;

    dns_name_init(&tkeyout.algorithm, NULL);
    RETERR(dns_name_dup(&tkeyin.algorithm, msg->mctx, &tkeyout.algorithm));
    freealg = ISC_TRUE;

    tkeyout.inception = tkeyout.expire = 0;
    tkeyout.mode = tkeyin.mode;
    tkeyout.error = 0;
    tkeyout.keylen = tkeyout.otherlen = 0;
    tkeyout.key = tkeyout.other = NULL;

    /*
     * A delete operation must have a fully specified key name.  If this
     * is not a delete, we do the following:
     * if (qname != ".")
     *  keyname = qname + defaultdomain
     * else
     *  keyname = <random hex> + defaultdomain
     */
    if (tkeyin.mode != DNS_TKEYMODE_DELETE) {
        dns_name_t prefix;
        isc_buffer_t *buf = NULL;
        unsigned char tdata[64];
        dns_tsigkey_t *tsigkey = NULL;

        dns_name_init(&tempkeyname, NULL);
        keyname = &tempkeyname;
        dns_name_init(&prefix, NULL);
        RETERR(isc_buffer_allocate(msg->mctx, &buf, 256));

        if (!dns_name_equal(qname, dns_rootname)) {
            unsigned int n = dns_name_countlabels(qname);
            dns_name_getlabelsequence(qname, 0, n - 1, &prefix);
        }
        else {
            static char hexdigits[16] = {
                '0', '1', '2', '3', '4', '5', '6', '7',
                '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
            unsigned char randomtext[32];
            isc_buffer_t b, b2;
            int i;

            result = isc_entropy_getdata(tctx->ectx,
                             randomtext,
                             sizeof(randomtext),
                             NULL, 0);
            if (result != ISC_R_SUCCESS) {
                dns_message_takebuffer(msg, &buf);
                goto failure;
            }

            for (i = sizeof(randomtext) - 2; i >= 0; i -= 2) {
                unsigned char val = randomtext[i/2];
                randomtext[i] = hexdigits[val >> 4];
                randomtext[i+1] = hexdigits[val & 0xF];
            }
            isc_buffer_init(&b, randomtext, sizeof(randomtext));
            isc_buffer_init(&b2, tdata, sizeof(tdata));
            isc_buffer_add(&b, sizeof(randomtext));
            result = dns_name_fromtext(&prefix, &b, NULL,
                           ISC_FALSE, &b2);
            if (result != ISC_R_SUCCESS) {
                dns_message_takebuffer(msg, &buf);
                goto failure;
            }
        }
        if (tctx->domain == NULL) {
            tkey_log("dns_tkey_processquery: tkey-domain not set");
            result = DNS_R_REFUSED;
            goto failure;
        }
        result = dns_name_concatenate(&prefix, tctx->domain,
                          keyname, buf);
        dns_message_takebuffer(msg, &buf);
        if (result != ISC_R_SUCCESS)
            goto failure;

        result = dns_tsigkey_find(&tsigkey, keyname, NULL, ring);
        if (result == ISC_R_SUCCESS) {
            tkeyout.error = dns_tsigerror_badname;
            dns_tsigkey_detach(&tsigkey);
            goto failure_with_tkey;
        }
        else if (result != ISC_R_NOTFOUND)
            goto failure;
    }
    else
        keyname = qname;

    switch (tkeyin.mode) {
        case DNS_TKEYMODE_DIFFIEHELLMAN:
            tkeyout.error = dns_rcode_noerror;
            RETERR(process_dhtkey(msg, signer, keyname, &tkeyin,
                          tctx, &tkeyout, ring,
                          &namelist));
            break;
        case DNS_TKEYMODE_GSSAPI:
            tkeyout.error = dns_rcode_noerror;
            RETERR(process_gsstkey(msg, signer, keyname, &tkeyin,
                           tctx, &tkeyout, ring,
                           &namelist));
            break;
        case DNS_TKEYMODE_DELETE:
            tkeyout.error = dns_rcode_noerror;
            RETERR(process_deletetkey(msg, signer, keyname,
                          &tkeyin, &tkeyout,
                          ring, &namelist));
            break;
        case DNS_TKEYMODE_SERVERASSIGNED:
        case DNS_TKEYMODE_RESOLVERASSIGNED:
            result = DNS_R_NOTIMP;
            goto failure;
        default:
            tkeyout.error = dns_tsigerror_badmode;
    }

 failure_with_tkey:
    dns_rdata_freestruct(&tkeyin);

    RETERR(dns_message_gettemprdata(msg, &rdata));
    RETERR(isc_buffer_allocate(msg->mctx, &dynbuf, 384));
    result = dns_rdata_fromstruct(rdata, tkeyout.common.rdclass,
                      tkeyout.common.rdtype, &tkeyout, dynbuf);
    dns_name_free(&tkeyout.algorithm, msg->mctx);
    freealg = ISC_FALSE;
    if (tkeyout.key != NULL)
        isc_mem_put(msg->mctx, tkeyout.key, tkeyout.keylen);
    if (tkeyout.other != NULL)
        isc_mem_put(msg->mctx, tkeyout.other, tkeyout.otherlen);
    if (result != ISC_R_SUCCESS)
        goto failure;

    RETERR(add_rdata_to_list(msg, keyname, rdata, 0, &namelist));

    isc_buffer_free(&dynbuf);

    RETERR(dns_message_reply(msg, ISC_TRUE));

    name = ISC_LIST_HEAD(namelist);
    while (name != NULL) {
        dns_name_t *next = ISC_LIST_NEXT(name, link);
        ISC_LIST_UNLINK(namelist, name, link);
        dns_message_addname(msg, name, DNS_SECTION_ANSWER);
        name = next;
    }

    return (ISC_R_SUCCESS);

 failure:
    if (freealg)
        dns_name_free(&tkeyout.algorithm, msg->mctx);
    if (tkeyin.common.rdtype == dns_rdatatype_tkey)
        dns_rdata_freestruct(&tkeyin);
    if (rdata != NULL)
        dns_message_puttemprdata(msg, &rdata);
    if (dynbuf != NULL)
        isc_buffer_free(&dynbuf);
    if (!ISC_LIST_EMPTY(namelist))
        free_namelist(msg, &namelist);
    return (result);
}

static isc_result_t
buildquery(dns_message_t *msg, dns_name_t *name,
       dns_rdata_tkey_t *tkey)
{
    dns_name_t *qname = NULL, *aname = NULL;
    dns_rdataset_t *question = NULL, *tkeyset = NULL;
    dns_rdatalist_t *tkeylist = NULL;
    dns_rdata_t *rdata = NULL;
    isc_buffer_t *dynbuf = NULL;
    isc_result_t result;

    REQUIRE(msg != NULL);
    REQUIRE(name != NULL);
    REQUIRE(tkey != NULL);

    RETERR(dns_message_gettempname(msg, &qname));
    RETERR(dns_message_gettempname(msg, &aname));

    RETERR(dns_message_gettemprdataset(msg, &question));
    dns_rdataset_init(question);
    dns_rdataset_makequestion(question, dns_rdataclass_any,
                  dns_rdatatype_tkey);

    RETERR(isc_buffer_allocate(msg->mctx, &dynbuf, 512));
    RETERR(dns_message_gettemprdata(msg, &rdata));
    RETERR(dns_rdata_fromstruct(rdata, dns_rdataclass_any,
                    dns_rdatatype_tkey, tkey, dynbuf));
    dns_message_takebuffer(msg, &dynbuf);

    RETERR(dns_message_gettemprdatalist(msg, &tkeylist));
    tkeylist->rdclass = dns_rdataclass_any;
    tkeylist->type = dns_rdatatype_tkey;
    tkeylist->covers = 0;
    tkeylist->ttl = 0;
    ISC_LIST_INIT(tkeylist->rdata);
    ISC_LIST_APPEND(tkeylist->rdata, rdata, link);

    RETERR(dns_message_gettemprdataset(msg, &tkeyset));
    dns_rdataset_init(tkeyset);
    RETERR(dns_rdatalist_tordataset(tkeylist, tkeyset));

    dns_name_init(qname, NULL);
    dns_name_clone(name, qname);

    dns_name_init(aname, NULL);
    dns_name_clone(name, aname);

    ISC_LIST_APPEND(qname->list, question, link);
    ISC_LIST_APPEND(aname->list, tkeyset, link);

    dns_message_addname(msg, qname, DNS_SECTION_QUESTION);
    dns_message_addname(msg, aname, DNS_SECTION_ADDITIONAL);

    return (ISC_R_SUCCESS);

 failure:
    if (qname != NULL)
        dns_message_puttempname(msg, &qname);
    if (aname != NULL)
        dns_message_puttempname(msg, &aname);
    if (question != NULL) {
        dns_rdataset_disassociate(question);
        dns_message_puttemprdataset(msg, &question);
    }
    if (dynbuf != NULL)
        isc_buffer_free(&dynbuf);
    return (result);
}

isc_result_t
dns_tkey_builddhquery(dns_message_t *msg, dst_key_t *key, dns_name_t *name,
              dns_name_t *algorithm, isc_buffer_t *nonce,
              isc_uint32_t lifetime)
{
    dns_rdata_tkey_t tkey;
    dns_rdata_t *rdata = NULL;
    isc_buffer_t *dynbuf = NULL;
    isc_region_t r;
    dns_name_t keyname;
    dns_namelist_t namelist;
    isc_result_t result;
    isc_stdtime_t now;

    REQUIRE(msg != NULL);
    REQUIRE(key != NULL);
    REQUIRE(dst_key_alg(key) == DNS_KEYALG_DH);
    REQUIRE(dst_key_isprivate(key));
    REQUIRE(name != NULL);
    REQUIRE(algorithm != NULL);

    tkey.common.rdclass = dns_rdataclass_any;
    tkey.common.rdtype = dns_rdatatype_tkey;
    ISC_LINK_INIT(&tkey.common, link);
    tkey.mctx = msg->mctx;
    dns_name_init(&tkey.algorithm, NULL);
    dns_name_clone(algorithm, &tkey.algorithm);
    isc_stdtime_get(&now);
    tkey.inception = now;
    tkey.expire = now + lifetime;
    tkey.mode = DNS_TKEYMODE_DIFFIEHELLMAN;
    if (nonce != NULL)
        isc_buffer_usedregion(nonce, &r);
    else {
        r.base = isc_mem_get(msg->mctx, 0);
        r.length = 0;
    }
    tkey.error = 0;
    tkey.key = r.base;
    tkey.keylen =  r.length;
    tkey.other = NULL;
    tkey.otherlen = 0;

    RETERR(buildquery(msg, name, &tkey));

    if (nonce == NULL)
        isc_mem_put(msg->mctx, r.base, 0);

    RETERR(dns_message_gettemprdata(msg, &rdata));
    RETERR(isc_buffer_allocate(msg->mctx, &dynbuf, 1024));
    RETERR(dst_key_todns(key, dynbuf));
    isc_buffer_usedregion(dynbuf, &r);
    dns_rdata_fromregion(rdata, dns_rdataclass_any,
                 dns_rdatatype_key, &r);
    dns_message_takebuffer(msg, &dynbuf);

    dns_name_init(&keyname, NULL);
    dns_name_clone(dst_key_name(key), &keyname);

    ISC_LIST_INIT(namelist);
    RETERR(add_rdata_to_list(msg, &keyname, rdata, 0, &namelist));
    dns_message_addname(msg, ISC_LIST_HEAD(namelist),
                DNS_SECTION_ADDITIONAL);

    return (ISC_R_SUCCESS);

 failure:

    if (dynbuf != NULL)
        isc_buffer_free(&dynbuf);
    return (result);
}

isc_result_t
dns_tkey_buildgssquery(dns_message_t *msg, dns_name_t *name,
               dns_name_t *gname, void *cred,
               isc_uint32_t lifetime, void **context)
{
    dns_rdata_tkey_t tkey;
    isc_result_t result;
    isc_stdtime_t now;
    isc_buffer_t token;
    unsigned char array[1024];

    REQUIRE(msg != NULL);
    REQUIRE(name != NULL);
    REQUIRE(gname != NULL);
    REQUIRE(context != NULL && *context == NULL);

    isc_buffer_init(&token, array, sizeof(array));
    result = dst_gssapi_initctx(gname, cred, NULL, &token, context);
    if (result != DNS_R_CONTINUE && result != ISC_R_SUCCESS)
        return (result);

    tkey.common.rdclass = dns_rdataclass_any;
    tkey.common.rdtype = dns_rdatatype_tkey;
    ISC_LINK_INIT(&tkey.common, link);
    tkey.mctx = NULL;
    dns_name_init(&tkey.algorithm, NULL);
    dns_name_clone(DNS_TSIG_GSSAPI_NAME, &tkey.algorithm);
    isc_stdtime_get(&now);
    tkey.inception = now;
    tkey.expire = now + lifetime;
    tkey.mode = DNS_TKEYMODE_GSSAPI;
    tkey.error = 0;
    tkey.key = isc_buffer_base(&token);
    tkey.keylen = isc_buffer_usedlength(&token);
    tkey.other = NULL;
    tkey.otherlen = 0;

    RETERR(buildquery(msg, name, &tkey));

    return (ISC_R_SUCCESS);

 failure:
    return (result);
}

isc_result_t
dns_tkey_builddeletequery(dns_message_t *msg, dns_tsigkey_t *key) {
    dns_rdata_tkey_t tkey;

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

    tkey.common.rdclass = dns_rdataclass_any;
    tkey.common.rdtype = dns_rdatatype_tkey;
    ISC_LINK_INIT(&tkey.common, link);
    tkey.mctx = msg->mctx;
    dns_name_init(&tkey.algorithm, NULL);
    dns_name_clone(key->algorithm, &tkey.algorithm);
    tkey.inception = tkey.expire = 0;
    tkey.mode = DNS_TKEYMODE_DELETE;
    tkey.error = 0;
    tkey.keylen = tkey.otherlen = 0;
    tkey.key = tkey.other = NULL;

    return (buildquery(msg, &key->name, &tkey));
}

static isc_result_t
find_tkey(dns_message_t *msg, dns_name_t **name, dns_rdata_t *rdata,
      int section)
{
    dns_rdataset_t *tkeyset;
    isc_result_t result;

    result = dns_message_firstname(msg, section);
    while (result == ISC_R_SUCCESS) {
        *name = NULL;
        dns_message_currentname(msg, section, name);
        tkeyset = NULL;
        result = dns_message_findtype(*name, dns_rdatatype_tkey, 0,
                          &tkeyset);
        if (result == ISC_R_SUCCESS) {
            result = dns_rdataset_first(tkeyset);
            if (result != ISC_R_SUCCESS)
                return (result);
            dns_rdataset_current(tkeyset, rdata);
            return (ISC_R_SUCCESS);
        }
        result = dns_message_nextname(msg, section);
    }
    if (result == ISC_R_NOMORE)
        return (ISC_R_NOTFOUND);
    return (result);
}

isc_result_t
dns_tkey_processdhresponse(dns_message_t *qmsg, dns_message_t *rmsg,
               dst_key_t *key, isc_buffer_t *nonce,
               dns_tsigkey_t **outkey, dns_tsig_keyring_t *ring)
{
    dns_rdata_t qtkeyrdata = DNS_RDATA_INIT, rtkeyrdata = DNS_RDATA_INIT;
    dns_name_t keyname, *tkeyname, *theirkeyname, *ourkeyname, *tempname;
    dns_rdataset_t *theirkeyset = NULL, *ourkeyset = NULL;
    dns_rdata_t theirkeyrdata = DNS_RDATA_INIT;
    dst_key_t *theirkey;
    dns_rdata_tkey_t qtkey, rtkey;
    unsigned char secretdata[256];
    unsigned int sharedsize;
    isc_buffer_t *shared = NULL, secret;
    isc_region_t r, r2;
    isc_result_t result;
    isc_boolean_t freertkey = ISC_FALSE;

    REQUIRE(qmsg != NULL);
    REQUIRE(rmsg != NULL);
    REQUIRE(key != NULL);
    REQUIRE(dst_key_alg(key) == DNS_KEYALG_DH);
    REQUIRE(dst_key_isprivate(key));
    if (outkey != NULL)
        REQUIRE(*outkey == NULL);
    REQUIRE(ring != NULL);

    if (rmsg->rcode != dns_rcode_noerror)
        return (ISC_RESULTCLASS_DNSRCODE + rmsg->rcode);
    RETERR(find_tkey(rmsg, &tkeyname, &rtkeyrdata, DNS_SECTION_ANSWER));
    RETERR(dns_rdata_tostruct(&rtkeyrdata, &rtkey, NULL));
    freertkey = ISC_TRUE;

    RETERR(find_tkey(qmsg, &tempname, &qtkeyrdata,
             DNS_SECTION_ADDITIONAL));
    RETERR(dns_rdata_tostruct(&qtkeyrdata, &qtkey, NULL));

    if (rtkey.error != dns_rcode_noerror ||
        rtkey.mode != DNS_TKEYMODE_DIFFIEHELLMAN ||
        rtkey.mode != qtkey.mode ||
        !dns_name_equal(&rtkey.algorithm, &qtkey.algorithm) ||
        rmsg->rcode != dns_rcode_noerror)
    {
        tkey_log("dns_tkey_processdhresponse: tkey mode invalid "
             "or error set");
        result = DNS_R_INVALIDTKEY;
        dns_rdata_freestruct(&qtkey);
        goto failure;
    }

    dns_rdata_freestruct(&qtkey);

    dns_name_init(&keyname, NULL);
    dns_name_clone(dst_key_name(key), &keyname);

    ourkeyname = NULL;
    ourkeyset = NULL;
    RETERR(dns_message_findname(rmsg, DNS_SECTION_ANSWER, &keyname,
                    dns_rdatatype_key, 0, &ourkeyname,
                    &ourkeyset));

    result = dns_message_firstname(rmsg, DNS_SECTION_ANSWER);
    while (result == ISC_R_SUCCESS) {
        theirkeyname = NULL;
        dns_message_currentname(rmsg, DNS_SECTION_ANSWER,
                    &theirkeyname);
        if (dns_name_equal(theirkeyname, ourkeyname))
            goto next;
        theirkeyset = NULL;
        result = dns_message_findtype(theirkeyname, dns_rdatatype_key,
                          0, &theirkeyset);
        if (result == ISC_R_SUCCESS) {
            RETERR(dns_rdataset_first(theirkeyset));
            break;
        }
 next:
        result = dns_message_nextname(rmsg, DNS_SECTION_ANSWER);
    }

    if (theirkeyset == NULL) {
        tkey_log("dns_tkey_processdhresponse: failed to find server "
             "key");
        result = DNS_R_INVALIDTKEY;
        result = ISC_R_NOTFOUND;
        goto failure;
    }

    dns_rdataset_current(theirkeyset, &theirkeyrdata);
    theirkey = NULL;
    RETERR(dns_dnssec_keyfromrdata(theirkeyname, &theirkeyrdata,
                       rmsg->mctx, &theirkey));

    RETERR(dst_key_secretsize(key, &sharedsize));
    RETERR(isc_buffer_allocate(rmsg->mctx, &shared, sharedsize));

    RETERR(dst_key_computesecret(theirkey, key, shared));

    isc_buffer_init(&secret, secretdata, sizeof(secretdata));

    r.base = rtkey.key;
    r.length = rtkey.keylen;
    if (nonce != NULL)
        isc_buffer_usedregion(nonce, &r2);
    else {
        r2.base = isc_mem_get(rmsg->mctx, 0);
        r2.length = 0;
    }
    RETERR(compute_secret(shared, &r2, &r, &secret));
    if (nonce == NULL)
        isc_mem_put(rmsg->mctx, r2.base, 0);

    isc_buffer_usedregion(&secret, &r);
    result = dns_tsigkey_create(tkeyname, &rtkey.algorithm,
                    r.base, r.length, ISC_TRUE,
                    NULL, rtkey.inception, rtkey.expire,
                    rmsg->mctx, ring, outkey);
    isc_buffer_free(&shared);
    dns_rdata_freestruct(&rtkey);
    dst_key_free(&theirkey);
    return (result);

 failure:
    if (shared != NULL)
        isc_buffer_free(&shared);

    if (theirkey != NULL)
        dst_key_free(&theirkey);

    if (freertkey)
        dns_rdata_freestruct(&rtkey);

    return (result);
}

isc_result_t
dns_tkey_processgssresponse(dns_message_t *qmsg, dns_message_t *rmsg,
                dns_name_t *gname, void *cred, void **context,
                dns_tsigkey_t **outkey, dns_tsig_keyring_t *ring)
{
    dns_rdata_t rtkeyrdata = DNS_RDATA_INIT, qtkeyrdata = DNS_RDATA_INIT;
    dns_name_t *tkeyname;
    dns_rdata_tkey_t rtkey, qtkey;
    isc_buffer_t outtoken;
    dst_key_t *dstkey = NULL;
    isc_region_t r;
    isc_result_t result;
    unsigned char array[1024];

    REQUIRE(qmsg != NULL);
    REQUIRE(rmsg != NULL);
    REQUIRE(gname != NULL);
    if (outkey != NULL)
        REQUIRE(*outkey == NULL);
    REQUIRE(ring != NULL);

    if (rmsg->rcode != dns_rcode_noerror)
        return (ISC_RESULTCLASS_DNSRCODE + rmsg->rcode);
    RETERR(find_tkey(rmsg, &tkeyname, &rtkeyrdata, DNS_SECTION_ANSWER));
    RETERR(dns_rdata_tostruct(&rtkeyrdata, &rtkey, NULL));

    RETERR(find_tkey(qmsg, &tkeyname, &qtkeyrdata,
             DNS_SECTION_ADDITIONAL));
    RETERR(dns_rdata_tostruct(&qtkeyrdata, &qtkey, NULL));

    if (rtkey.error != dns_rcode_noerror ||
        rtkey.mode != DNS_TKEYMODE_GSSAPI ||
        !dns_name_equal(&rtkey.algorithm, &rtkey.algorithm))
    {
        tkey_log("dns_tkey_processdhresponse: tkey mode invalid "
             "or error set");
        result = DNS_R_INVALIDTKEY;
        goto failure;
    }

    isc_buffer_init(&outtoken, array, sizeof(array));
    r.base = rtkey.key;
    r.length = rtkey.keylen;
    RETERR(dst_gssapi_initctx(gname, cred, &r, &outtoken, context));

    dstkey = NULL;
    RETERR(dst_key_fromgssapi(dns_rootname, *context, rmsg->mctx,
                  &dstkey));

    RETERR(dns_tsigkey_createfromkey(tkeyname, DNS_TSIG_GSSAPI_NAME,
                     dstkey, ISC_TRUE, NULL,
                     rtkey.inception, rtkey.expire,
                     rmsg->mctx, ring, outkey));

    dns_rdata_freestruct(&rtkey);
    return (result);

 failure:
    return (result);
}

isc_result_t
dns_tkey_processdeleteresponse(dns_message_t *qmsg, dns_message_t *rmsg,
                   dns_tsig_keyring_t *ring)
{
    dns_rdata_t qtkeyrdata = DNS_RDATA_INIT, rtkeyrdata = DNS_RDATA_INIT;
    dns_name_t *tkeyname, *tempname;
    dns_rdata_tkey_t qtkey, rtkey;
    dns_tsigkey_t *tsigkey = NULL;
    isc_result_t result;

    REQUIRE(qmsg != NULL);
    REQUIRE(rmsg != NULL);

    if (rmsg->rcode != dns_rcode_noerror)
        return(ISC_RESULTCLASS_DNSRCODE + rmsg->rcode);

    RETERR(find_tkey(rmsg, &tkeyname, &rtkeyrdata, DNS_SECTION_ANSWER));
    RETERR(dns_rdata_tostruct(&rtkeyrdata, &rtkey, NULL));

    RETERR(find_tkey(qmsg, &tempname, &qtkeyrdata,
             DNS_SECTION_ADDITIONAL));
    RETERR(dns_rdata_tostruct(&qtkeyrdata, &qtkey, NULL));

    if (rtkey.error != dns_rcode_noerror ||
        rtkey.mode != DNS_TKEYMODE_DELETE ||
        rtkey.mode != qtkey.mode ||
        !dns_name_equal(&rtkey.algorithm, &qtkey.algorithm) ||
        rmsg->rcode != dns_rcode_noerror)
    {
        tkey_log("dns_tkey_processdeleteresponse: tkey mode invalid "
             "or error set");
        result = DNS_R_INVALIDTKEY;
        dns_rdata_freestruct(&qtkey);
        dns_rdata_freestruct(&rtkey);
        goto failure;
    }

    dns_rdata_freestruct(&qtkey);

    RETERR(dns_tsigkey_find(&tsigkey, tkeyname, &rtkey.algorithm, ring));

    dns_rdata_freestruct(&rtkey);

    /*
     * Mark the key as deleted.
     */
    dns_tsigkey_setdeleted(tsigkey);
    /*
     * Release the reference.
     */
    dns_tsigkey_detach(&tsigkey);

 failure:
    return (result);
}