lib/dns/tsig.c

	tsig.c revision 3b2efab212088496d5588ca5ed2d802c72d21a08
/*
 * Copyright (C) 1999, 2000  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: tsig.c,v 1.77 2000/07/21 22:38:29 bwelling Exp $
 * Principal Author: Brian Wellington
 */

#include <config.h>
#include <stdlib.h>     /* Required for abs(). */

#include <isc/buffer.h>
#include <isc/mem.h>
#include <isc/once.h>
#include <isc/string.h>     /* Required for HP/UX (and others?) */
#include <isc/util.h>

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

#include <dst/result.h>

#define TSIG_MAGIC      0x54534947  /* TSIG */
#define VALID_TSIG_KEY(x)   ISC_MAGIC_VALID(x, TSIG_MAGIC)

#define is_response(msg) (msg->flags & DNS_MESSAGEFLAG_QR)

static isc_once_t once = ISC_ONCE_INIT;
static dns_name_t hmacmd5_name;
dns_name_t *dns_tsig_hmacmd5_name = &hmacmd5_name;

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

static void
dns_tsig_inithmac(void) {
    isc_constregion_t r;
    const char *str = "\010HMAC-MD5\007SIG-ALG\003REG\003INT";

    dns_name_init(&hmacmd5_name, NULL);
    r.base = str;
    r.length = strlen(str) + 1;
    dns_name_fromregion(&hmacmd5_name, (isc_region_t *)&r);
    dns_tsig_hmacmd5_name = &hmacmd5_name;
}

isc_result_t
dns_tsigkey_create(dns_name_t *name, dns_name_t *algorithm,
           unsigned char *secret, int length, isc_boolean_t generated,
           dns_name_t *creator, isc_stdtime_t inception,
           isc_stdtime_t expire, isc_mem_t *mctx,
           dns_tsig_keyring_t *ring, dns_tsigkey_t **key)
{
    isc_buffer_t b;
    isc_uint16_t alg;
    dns_tsigkey_t *tkey;
    isc_result_t ret;

    REQUIRE(key == NULL || *key == NULL);
    REQUIRE(name != NULL);
    REQUIRE(algorithm != NULL);
    REQUIRE(length >= 0);
    if (length > 0)
        REQUIRE(secret != NULL);
    REQUIRE(mctx != NULL);

    RUNTIME_CHECK(isc_once_do(&once, dns_tsig_inithmac) == ISC_R_SUCCESS);
    if (!dns_name_equal(algorithm, DNS_TSIG_HMACMD5_NAME))
        return (ISC_R_NOTFOUND);
    else
        alg = DST_ALG_HMACMD5;

    tkey = (dns_tsigkey_t *) isc_mem_get(mctx, sizeof(dns_tsigkey_t));
    if (tkey == NULL)
        return (ISC_R_NOMEMORY);

    dns_name_init(&tkey->name, NULL);
    ret = dns_name_dup(name, mctx, &tkey->name);
    if (ret != ISC_R_SUCCESS)
        goto cleanup_key;
    dns_name_downcase(&tkey->name, &tkey->name, NULL);

    dns_name_init(&tkey->algorithm, NULL);
    ret = dns_name_dup(algorithm, mctx, &tkey->algorithm);
    if (ret != ISC_R_SUCCESS)
        goto cleanup_name;
    dns_name_downcase(&tkey->algorithm, &tkey->algorithm, NULL);

    if (creator != NULL) {
        tkey->creator = isc_mem_get(mctx, sizeof(dns_name_t));
        if (tkey->creator == NULL) {
            ret = ISC_R_NOMEMORY;
            goto cleanup_algorithm;
        }
        dns_name_init(tkey->creator, NULL);
        ret = dns_name_dup(creator, mctx, tkey->creator);
        if (ret != ISC_R_SUCCESS) {
            isc_mem_put(mctx, tkey->creator, sizeof(dns_name_t));
            goto cleanup_algorithm;
        }
    }
    else
        tkey->creator = NULL;

    tkey->key = NULL;
    tkey->ring = ring;
    tkey->refs = 0;

    if (length > 0) {
        dns_tsigkey_t *tmp = NULL;

        isc_buffer_init(&b, secret, length);
        isc_buffer_add(&b, length);
        ret = dst_key_frombuffer(name, alg,
                     DNS_KEYOWNER_ENTITY,
                     DNS_KEYPROTO_DNSSEC,
                     &b, mctx, &tkey->key);
        if (ret != ISC_R_SUCCESS)
            goto cleanup_algorithm;

        if (ring != NULL) {
            RWLOCK(&ring->lock, isc_rwlocktype_write);
            ret = dns_rbt_findname(ring->keys, name, 0, NULL,
                           (void *)&tmp);
            if (ret == ISC_R_SUCCESS) {
                ret = ISC_R_EXISTS;
                RWUNLOCK(&ring->lock, isc_rwlocktype_write);
                goto cleanup_algorithm;
            }
            INSIST(ret == ISC_R_NOTFOUND ||
                   ret == DNS_R_PARTIALMATCH);
            ret = dns_rbt_addname(ring->keys, name, tkey);
            if (ret != ISC_R_SUCCESS) {
                ret = ISC_R_EXISTS;
                RWUNLOCK(&ring->lock, isc_rwlocktype_write);
                goto cleanup_algorithm;
            }
            tkey->refs++;
            RWUNLOCK(&ring->lock, isc_rwlocktype_write);
        }
    }

    if (key != NULL)
        tkey->refs++;
    tkey->generated = generated;
    tkey->inception = inception;
    tkey->expire = expire;
    tkey->mctx = mctx;
    ret = isc_mutex_init(&tkey->lock);
    if (ret != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "isc_mutex_init() failed: %s",
                 isc_result_totext(ret));
        return (ISC_R_UNEXPECTED);
    }

    tkey->magic = TSIG_MAGIC;

    if (key != NULL)
        *key = tkey;

    return (ISC_R_SUCCESS);

cleanup_algorithm:
    dns_name_free(&tkey->algorithm, mctx);
cleanup_name:
    dns_name_free(&tkey->name, mctx);
cleanup_key:
    isc_mem_put(mctx, *key, sizeof(dns_tsigkey_t));

    return (ret);
}

void
dns_tsigkey_attach(dns_tsigkey_t *source, dns_tsigkey_t **targetp) {
    REQUIRE(VALID_TSIG_KEY(source));
    REQUIRE(targetp != NULL && *targetp == NULL);

    LOCK(&source->lock);
    source->refs++;
    UNLOCK(&source->lock);
    *targetp = source;
}

static void
tsigkey_free(dns_tsigkey_t *key) {
    REQUIRE(VALID_TSIG_KEY(key));

    key->magic = 0;
    dns_name_free(&key->name, key->mctx);
    dns_name_free(&key->algorithm, key->mctx);
    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_put(key->mctx, key, sizeof(dns_tsigkey_t));
}

void
dns_tsigkey_detach(dns_tsigkey_t **keyp) {
    dns_tsigkey_t *key;
    isc_boolean_t should_free = ISC_FALSE;

    REQUIRE(keyp != NULL);
    REQUIRE(VALID_TSIG_KEY(*keyp));
    key = *keyp;
    *keyp = NULL;

    LOCK(&key->lock);
    key->refs--;
    if (key->refs == 0)
        should_free = ISC_TRUE;
    UNLOCK(&key->lock);
    if (should_free)
        tsigkey_free(key);
}

void
dns_tsigkey_setdeleted(dns_tsigkey_t *key) {
    REQUIRE(VALID_TSIG_KEY(key));
    REQUIRE(key->ring != NULL);

    RWLOCK(&key->ring->lock, isc_rwlocktype_write);
    (void)dns_rbt_deletename(key->ring->keys, &key->name, ISC_FALSE);
    RWUNLOCK(&key->ring->lock, isc_rwlocktype_write);
}

isc_result_t
dns_tsig_sign(dns_message_t *msg) {
    dns_tsigkey_t *key;
    dns_rdata_any_tsig_t tsig, querytsig;
    unsigned char data[128];
    isc_buffer_t databuf, sigbuf;
    isc_buffer_t *dynbuf;
    dns_name_t *owner;
    dns_rdata_t *rdata;
    dns_rdatalist_t *datalist;
    dns_rdataset_t *dataset;
    isc_region_t r, r2;
    isc_stdtime_t now;
    isc_mem_t *mctx;
    dst_context_t *ctx = NULL;
    isc_result_t ret;

    REQUIRE(msg != NULL);
    REQUIRE(VALID_TSIG_KEY(dns_message_gettsigkey(msg)));

    /*
     * If this is a response, there should be a query tsig.
     */
    if (is_response(msg) && msg->querytsig == NULL)
        return (DNS_R_EXPECTEDTSIG);

    dynbuf = NULL;

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

    tsig.mctx = mctx;
    tsig.common.rdclass = dns_rdataclass_any;
    tsig.common.rdtype = dns_rdatatype_tsig;
    ISC_LINK_INIT(&tsig.common, link);
    dns_name_init(&tsig.algorithm, NULL);
    dns_name_clone(&key->algorithm, &tsig.algorithm);

    isc_stdtime_get(&now);
    tsig.timesigned = now;
    tsig.fudge = DNS_TSIG_FUDGE;

    tsig.originalid = msg->id;

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

    if (is_response(msg))
        tsig.error = msg->querytsigstatus;
    else
        tsig.error = dns_rcode_noerror;

    if (tsig.error != dns_tsigerror_badtime) {
        tsig.otherlen = 0;
        tsig.other = NULL;
    }
    else {
        isc_buffer_t otherbuf;
        tsig.otherlen = 6;
        tsig.other = (unsigned char *)isc_mem_get(mctx, tsig.otherlen);
        if (tsig.other == NULL) {
            ret = ISC_R_NOMEMORY;
            goto cleanup_other;
        }
        isc_buffer_init(&otherbuf, tsig.other, tsig.otherlen);
        isc_buffer_putuint16(&otherbuf,
                     (isc_uint16_t)(tsig.timesigned >> 32));
        isc_buffer_putuint32(&otherbuf,
                     (isc_uint32_t)(tsig.timesigned &
                            0xFFFFFFFF));

    }
    if (!dns_tsigkey_empty(key) && tsig.error != dns_tsigerror_badsig) {
        unsigned char header[DNS_MESSAGE_HEADERLEN];
        isc_buffer_t headerbuf;
        unsigned int sigsize;

        ret = dst_context_create(key->key, mctx, &ctx);
        if (ret != ISC_R_SUCCESS)
            goto cleanup_other;

        /*
         * If this is a response, digest the query signature.
         */
        if (is_response(msg)) {
            dns_rdata_t querytsigrdata;

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

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

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

            dns_name_toregion(&tsig.algorithm, &r);
            ret = dst_context_adddata(ctx, &r);
            if (ret != ISC_R_SUCCESS)
                goto cleanup_context;

        }
        /* Digest the timesigned and fudge */
        isc_buffer_clear(&databuf);
        if (tsig.error != dns_tsigerror_badtime) {
            isc_buffer_putuint16(&databuf,
                         (isc_uint16_t)(tsig.timesigned >>
                                32));
            isc_buffer_putuint32(&databuf,
                         (isc_uint32_t)(tsig.timesigned &
                                0xFFFFFFFF));
        }
        else {
            isc_uint64_t querysigned = querytsig.timesigned;
            isc_buffer_putuint16(&databuf,
                         (isc_uint16_t)(querysigned >>
                                32));
            isc_buffer_putuint32(&databuf,
                         (isc_uint16_t)(querysigned &
                                0xFFFFFFFF));
        }
        isc_buffer_putuint16(&databuf, tsig.fudge);
        isc_buffer_usedregion(&databuf, &r);
        ret = dst_context_adddata(ctx, &r);
        if (ret != 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);
            ret = dst_context_adddata(ctx, &r);
            if (ret != ISC_R_SUCCESS)
                goto cleanup_context;

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

        ret = dst_key_sigsize(key->key, &sigsize);
        if (ret != ISC_R_SUCCESS)
            goto cleanup_context;
        tsig.siglen = sigsize;
        tsig.signature = (unsigned char *)
                  isc_mem_get(mctx, tsig.siglen);
        if (tsig.signature == NULL) {
            ret = ISC_R_NOMEMORY;
            goto cleanup_context;
        }

        isc_buffer_init(&sigbuf, tsig.signature, tsig.siglen);
        ret = dst_context_sign(ctx, &sigbuf);
        if (ret != ISC_R_SUCCESS)
            goto cleanup_signature;
        dst_context_destroy(&ctx);
    }
    else {
        tsig.siglen = 0;
        tsig.signature = NULL;
    }

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

    dns_message_takebuffer(msg, &dynbuf);

    if (tsig.signature != NULL) {
        isc_mem_put(mctx, tsig.signature, tsig.siglen);
        tsig.signature = NULL;
    }
    if (tsig.other != NULL) {
        isc_mem_put(mctx, tsig.other, tsig.otherlen);
        tsig.other = NULL;
    }

    owner = NULL;
    ret = dns_message_gettempname(msg, &owner);
    if (ret != ISC_R_SUCCESS)
        goto cleanup_dynbuf;
    dns_name_toregion(&key->name, &r);
    dynbuf = NULL;
    ret = isc_buffer_allocate(mctx, &dynbuf, r.length);
    if (ret != ISC_R_SUCCESS)
        goto cleanup_dynbuf;
    isc_buffer_availableregion(dynbuf, &r2);
    memcpy(r2.base, r.base, r.length);
    dns_name_init(owner, NULL);
    dns_name_fromregion(owner, &r2);
    dns_message_takebuffer(msg, &dynbuf);

    datalist = NULL;
    ret = dns_message_gettemprdatalist(msg, &datalist);
    if (ret != ISC_R_SUCCESS)
        goto cleanup_dynbuf;
    datalist->rdclass = dns_rdataclass_any;
    datalist->type = dns_rdatatype_tsig;
    datalist->covers = 0;
    datalist->ttl = 0;
    ISC_LIST_INIT(datalist->rdata);
    ISC_LIST_APPEND(datalist->rdata, rdata, link);
    dataset = NULL;
    ret = dns_message_gettemprdataset(msg, &dataset);
    if (ret != ISC_R_SUCCESS)
        goto cleanup_dynbuf;
    dns_rdataset_init(dataset);
    dns_rdatalist_tordataset(datalist, dataset);
    msg->tsig = dataset;
    msg->tsigname = owner;

    return (ISC_R_SUCCESS);

cleanup_dynbuf:
    if (dynbuf != NULL)
        isc_buffer_free(&dynbuf);
cleanup_signature:
    if (tsig.signature != NULL)
        isc_mem_put(mctx, tsig.signature, tsig.siglen);
cleanup_context:
    if (ctx != NULL)
        dst_context_destroy(&ctx);
cleanup_other:
    if (tsig.other != NULL)
        isc_mem_put(mctx, tsig.other, tsig.otherlen);

    return (ret);
}

isc_result_t
dns_tsig_verify(isc_buffer_t *source, dns_message_t *msg,
        dns_tsig_keyring_t *ring1, dns_tsig_keyring_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;
    dns_rdata_t rdata;
    isc_stdtime_t now;
    isc_result_t ret;
    dns_tsigkey_t *tsigkey;
    dst_key_t *key = NULL;
    unsigned char header[DNS_MESSAGE_HEADERLEN];
    dst_context_t *ctx = NULL;
    isc_mem_t *mctx;
    isc_uint16_t addcount, id;

    REQUIRE(source != NULL);
    REQUIRE(DNS_MESSAGE_VALID(msg));
    tsigkey = dns_message_gettsigkey(msg);
    REQUIRE(tsigkey == NULL || VALID_TSIG_KEY(tsigkey));

    msg->verify_attempted = 1;

    if (msg->tcp_continuation)
        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 (is_response(msg) &&
        (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;
    ret = dns_rdataset_first(msg->tsig);
    if (ret != ISC_R_SUCCESS)
        return (ret);
    dns_rdataset_current(msg->tsig, &rdata);
    ret = dns_rdata_tostruct(&rdata, &tsig, NULL);
    if (ret != ISC_R_SUCCESS)
        return (ret);
    if (is_response(msg)) {
        ret = dns_rdataset_first(msg->querytsig);
        if (ret != ISC_R_SUCCESS)
            return (ret);
        dns_rdataset_current(msg->querytsig, &rdata);
        ret = dns_rdata_tostruct(&rdata, &querytsig, NULL);
        if (ret != ISC_R_SUCCESS)
            return (ret);
    }

    /*
     * Do the key name and algorithm match that of the query?
     */
    if (is_response(msg) &&
        (!dns_name_equal(keyname, &tsigkey->name) ||
         !dns_name_equal(&tsig.algorithm, &querytsig.algorithm)))
    {
        msg->tsigstatus = dns_tsigerror_badkey;
        return (DNS_R_TSIGVERIFYFAILURE);
    }

    /*
     * Get the current time.
     */
    isc_stdtime_get(&now);

    /*
     * Find dns_tsigkey_t based on keyname.
     */
    if (tsigkey == NULL) {
        ret = ISC_R_NOTFOUND;
        if (ring1 != NULL)
            ret = dns_tsigkey_find(&tsigkey, keyname,
                           &tsig.algorithm, ring1);
        if (ret == ISC_R_NOTFOUND && ring2 != NULL)
            ret = dns_tsigkey_find(&tsigkey, keyname,
                           &tsig.algorithm, ring2);
        if (ret != ISC_R_SUCCESS) {
            msg->tsigstatus = dns_tsigerror_badkey;
            ret = dns_tsigkey_create(keyname, &tsig.algorithm,
                         NULL, 0, ISC_FALSE, NULL,
                         now, now,
                         mctx, NULL, &msg->tsigkey);
            if (ret != ISC_R_SUCCESS)
                return (ret);
            return (DNS_R_TSIGVERIFYFAILURE);
        }
        msg->tsigkey = tsigkey;
    }

    key = tsigkey->key;

    /*
     * Is the time ok?
     */
    if (abs(now - tsig.timesigned) > tsig.fudge) {
        msg->tsigstatus = dns_tsigerror_badtime;
        return (DNS_R_TSIGVERIFYFAILURE);
    }

    if (tsig.siglen > 0) {
        sig_r.base = tsig.signature;
        sig_r.length = tsig.siglen;

        ret = dst_context_create(key, mctx, &ctx);
        if (ret != ISC_R_SUCCESS)
            goto cleanup_key;

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

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

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

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

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

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

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

        isc_buffer_clear(&databuf);
        isc_buffer_putuint16(&databuf, (isc_uint16_t)(tsig.timesigned
                                  >> 32));
        isc_buffer_putuint32(&databuf, (isc_uint32_t)(tsig.timesigned
                                  & 0xFFFFFFFF));
        isc_buffer_putuint16(&databuf, tsig.fudge);
        isc_buffer_putuint16(&databuf, tsig.error);
        isc_buffer_putuint16(&databuf, tsig.otherlen);
        isc_buffer_usedregion(&databuf, &r);
        ret = dst_context_adddata(ctx, &r);
        if (ret != ISC_R_SUCCESS)
            goto cleanup_context;

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

        ret = dst_context_verify(ctx, &sig_r);
        if (ret == DST_R_VERIFYFAILURE) {
            msg->tsigstatus = dns_tsigerror_badsig;
            ret = DNS_R_TSIGVERIFYFAILURE;
            goto cleanup_context;
        }
        else if (ret != ISC_R_SUCCESS)
            goto cleanup_context;

        dst_context_destroy(&ctx);
    }
    else if (tsig.error != dns_tsigerror_badsig &&
         tsig.error != dns_tsigerror_badkey)
    {
        msg->tsigstatus = dns_tsigerror_badsig;
        return (DNS_R_TSIGVERIFYFAILURE);
    }

    msg->tsigstatus = dns_rcode_noerror;

    if (tsig.error != dns_rcode_noerror)
        return (DNS_R_TSIGERRORSET);

    msg->verified_sig = 1;

    return (ISC_R_SUCCESS);

cleanup_context:
    if (ctx != NULL)
        dst_context_destroy(&ctx);
cleanup_key:
    if (dns_tsigkey_empty(tsigkey))
        dns_tsigkey_detach(&tsigkey);

    return (ret);
}

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;
    dns_rdata_t rdata;
    isc_stdtime_t now;
    isc_result_t ret;
    dns_tsigkey_t *tsigkey;
    dst_key_t *key = NULL;
    unsigned char header[DNS_MESSAGE_HEADERLEN];
    isc_uint16_t addcount, id;
    isc_boolean_t has_tsig = ISC_FALSE;
    isc_mem_t *mctx;

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

    mctx = msg->mctx;

    tsigkey = dns_message_gettsigkey(msg);

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

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

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

        /*
         * Is the time ok?
         */
        isc_stdtime_get(&now);
        if (abs(now - tsig.timesigned) > tsig.fudge) {
            msg->tsigstatus = dns_tsigerror_badtime;
            ret = DNS_R_TSIGVERIFYFAILURE;
            goto cleanup_querystruct;
        }
    }

    key = tsigkey->key;

    if (msg->tsigctx == NULL) {
        ret = dst_context_create(key, mctx, &msg->tsigctx);
        if (ret != 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);
        ret = dst_context_adddata(msg->tsigctx, &r);
        if (ret != 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;
            ret = dst_context_adddata(msg->tsigctx, &r);
            if (ret != ISC_R_SUCCESS)
                goto cleanup_context;
        }
    }

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

    /*
     * Decrement the additional field counter if necessary.
     */
    if (has_tsig) {
        memcpy(&addcount, &header[DNS_MESSAGE_HEADERLEN - 2], 2);
        addcount = htons(ntohs(addcount) - 1);
        memcpy(&header[DNS_MESSAGE_HEADERLEN - 2], &addcount, 2);
    }

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

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

    /*
     * Digest the time signed and fudge.
     */
    if (has_tsig) {
        isc_buffer_init(&databuf, data, sizeof(data));
        isc_buffer_putuint16(&databuf, (isc_uint16_t)(tsig.timesigned
                                  >> 32));
        isc_buffer_putuint32(&databuf, (isc_uint32_t)(tsig.timesigned
                                  & 0xFFFFFFFF));
        isc_buffer_putuint16(&databuf, tsig.fudge);
        isc_buffer_usedregion(&databuf, &r);
        ret = dst_context_adddata(msg->tsigctx, &r);
        if (ret != 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)
                ret = DNS_R_TSIGERRORSET;
            else
                ret = DNS_R_TSIGVERIFYFAILURE;
            goto cleanup_context;
        }

        ret = dst_context_verify(msg->tsigctx, &sig_r);
        if (ret == DST_R_VERIFYFAILURE) {
            msg->tsigstatus = dns_tsigerror_badsig;
            ret = DNS_R_TSIGVERIFYFAILURE;
            goto cleanup_context;
        }
        else if (ret != ISC_R_SUCCESS)
            goto cleanup_context;

        dst_context_destroy(&msg->tsigctx);
    }

    msg->tsigstatus = dns_rcode_noerror;
    return (ISC_R_SUCCESS);

 cleanup_context:
    dst_context_destroy(&msg->tsigctx);

 cleanup_querystruct:
    dns_rdata_freestruct(&querytsig);

    return (ret);

}

isc_result_t
dns_tsigkey_find(dns_tsigkey_t **tsigkey, dns_name_t *name,
         dns_name_t *algorithm, dns_tsig_keyring_t *ring)
{
    dns_tsigkey_t *key;
    isc_stdtime_t now;
    isc_result_t result;

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

    isc_stdtime_get(&now);
    RWLOCK(&ring->lock, isc_rwlocktype_read);
    key = NULL;
    result = dns_rbt_findname(ring->keys, name, 0, NULL, (void *)&key);
    if (result == DNS_R_PARTIALMATCH || result == ISC_R_NOTFOUND) {
        RWUNLOCK(&ring->lock, isc_rwlocktype_read);
        return (ISC_R_NOTFOUND);
    }
    if (algorithm != NULL && !dns_name_equal(&key->algorithm, algorithm)) {
        RWUNLOCK(&ring->lock, isc_rwlocktype_read);
        return (ISC_R_NOTFOUND);
    }
    if (key->inception != key->expire && key->expire < now) {
        /*
         * The key has expired.
         */
        RWUNLOCK(&ring->lock, isc_rwlocktype_read);
        LOCK(&key->lock);
        key->refs--;
        UNLOCK(&key->lock);
        RWLOCK(&ring->lock, isc_rwlocktype_write);
        (void) dns_rbt_deletename(ring->keys, name, ISC_FALSE);
        RWUNLOCK(&ring->lock, isc_rwlocktype_write);
        return (ISC_R_NOTFOUND);
    }

    LOCK(&key->lock);
    key->refs++;
    UNLOCK(&key->lock);
    RWUNLOCK(&ring->lock, isc_rwlocktype_read);
    *tsigkey = key;
    return (ISC_R_SUCCESS);
}

static void
free_tsignode(void *node, void *_unused) {
    dns_tsigkey_t *key;

    UNUSED(_unused);

    REQUIRE(node != NULL);

    key = node;
    dns_tsigkey_detach(&key);
}

isc_result_t
dns_tsigkeyring_create(isc_mem_t *mctx, dns_tsig_keyring_t **ringp) {
    isc_result_t result;
    dns_tsig_keyring_t *ring;

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

    ring = isc_mem_get(mctx, sizeof(dns_tsig_keyring_t));
    if (ring == NULL)
        return (ISC_R_NOMEMORY);

    result = isc_rwlock_init(&ring->lock, 0, 0);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "isc_rwlock_init() failed: %s",
                 isc_result_totext(result));
        return (ISC_R_UNEXPECTED);
    }

    ring->keys = NULL;
    result = dns_rbt_create(mctx, free_tsignode, NULL, &ring->keys);
    if (result != ISC_R_SUCCESS) {
        isc_rwlock_destroy(&ring->lock);
        isc_mem_put(mctx, ring, sizeof(dns_tsig_keyring_t));
        return (result);
    }

    ring->mctx = mctx;

    *ringp = ring;
    return (ISC_R_SUCCESS);
}

void
dns_tsigkeyring_destroy(dns_tsig_keyring_t **ringp) {
    dns_tsig_keyring_t *ring;

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

    ring = *ringp;
    *ringp = NULL;

    dns_rbt_destroy(&ring->keys);
    isc_rwlock_destroy(&ring->lock);
    isc_mem_put(ring->mctx, ring, sizeof(dns_tsig_keyring_t));
}