lib/dns/rdata.c

	rdata.c revision 499b34cea04a46823d003d4c0520c8b03e8513cb
/*
 * Copyright (C) 1998-2001  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: rdata.c,v 1.141 2001/01/09 21:51:20 bwelling Exp $ */

#include <config.h>
#include <ctype.h>

#include <isc/base64.h>
#include <isc/hex.h>
#include <isc/lex.h>
#include <isc/mem.h>
#include <isc/print.h>
#include <isc/string.h>
#include <isc/util.h>

#include <dns/callbacks.h>
#include <dns/cert.h>
#include <dns/compress.h>
#include <dns/keyflags.h>
#include <dns/rcode.h>
#include <dns/rdata.h>
#include <dns/rdataclass.h>
#include <dns/rdatastruct.h>
#include <dns/rdatatype.h>
#include <dns/result.h>
#include <dns/secalg.h>
#include <dns/secproto.h>
#include <dns/time.h>
#include <dns/ttl.h>

#define RETERR(x) do { \
    isc_result_t _r = (x); \
    if (_r != ISC_R_SUCCESS) \
        return (_r); \
    } while (0)

#define ARGS_FROMTEXT   int rdclass, dns_rdatatype_t type, \
            isc_lex_t *lexer, dns_name_t *origin, \
            isc_boolean_t downcase, isc_buffer_t *target

#define ARGS_TOTEXT dns_rdata_t *rdata, dns_rdata_textctx_t *tctx, \
            isc_buffer_t *target

#define ARGS_FROMWIRE   int rdclass, dns_rdatatype_t type, \
            isc_buffer_t *source, dns_decompress_t *dctx, \
            isc_boolean_t downcase, isc_buffer_t *target

#define ARGS_TOWIRE dns_rdata_t *rdata, dns_compress_t *cctx, \
            isc_buffer_t *target

#define ARGS_COMPARE    const dns_rdata_t *rdata1, const dns_rdata_t *rdata2

#define ARGS_FROMSTRUCT int rdclass, dns_rdatatype_t type, \
            void *source, isc_buffer_t *target

#define ARGS_TOSTRUCT   dns_rdata_t *rdata, void *target, isc_mem_t *mctx

#define ARGS_FREESTRUCT void *source

#define ARGS_ADDLDATA   dns_rdata_t *rdata, dns_additionaldatafunc_t add, \
            void *arg

#define ARGS_DIGEST dns_rdata_t *rdata, dns_digestfunc_t digest, void *arg

/*
 * Context structure for the totext_ functions.
 * Contains formatting options for rdata-to-text
 * conversion.
 */
typedef struct dns_rdata_textctx {
    dns_name_t *origin; /* Current origin, or NULL. */
    unsigned int flags; /* DNS_STYLEFLAG_* */
    unsigned int width; /* Width of rdata column. */
    const char *linebreak;  /* Line break string. */
} dns_rdata_textctx_t;

static isc_result_t
txt_totext(isc_region_t *source, isc_buffer_t *target);

static isc_result_t
txt_fromtext(isc_textregion_t *source, isc_buffer_t *target);

static isc_result_t
txt_fromwire(isc_buffer_t *source, isc_buffer_t *target);

static isc_boolean_t
name_prefix(dns_name_t *name, dns_name_t *origin, dns_name_t *target);

static unsigned int
name_length(dns_name_t *name);

static isc_result_t
str_totext(const char *source, isc_buffer_t *target);

static isc_boolean_t
buffer_empty(isc_buffer_t *source);

static void
buffer_fromregion(isc_buffer_t *buffer, isc_region_t *region);

static isc_result_t
uint32_tobuffer(isc_uint32_t, isc_buffer_t *target);

static isc_result_t
uint16_tobuffer(isc_uint32_t, isc_buffer_t *target);

static isc_result_t
uint8_tobuffer(isc_uint32_t, isc_buffer_t *target);

static isc_result_t
name_tobuffer(dns_name_t *name, isc_buffer_t *target);

static isc_uint32_t
uint32_fromregion(isc_region_t *region);

static isc_uint16_t
uint16_fromregion(isc_region_t *region);

static isc_uint8_t
uint8_fromregion(isc_region_t *region);

static isc_result_t
mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length);

static int
compare_region(isc_region_t *r1, isc_region_t *r2);

static int
hexvalue(char value);

static int
decvalue(char value);

static isc_result_t
btoa_totext(unsigned char *inbuf, int inbuflen, isc_buffer_t *target);

static isc_result_t
atob_tobuffer(isc_lex_t *lexer, isc_buffer_t *target);

static void
default_fromtext_callback(dns_rdatacallbacks_t *callbacks, const char *, ...);

static void
fromtext_error(void (*callback)(dns_rdatacallbacks_t *, const char *, ...),
           dns_rdatacallbacks_t *callbacks, const char *name,
           unsigned long line, isc_token_t *token, isc_result_t result);

static void
fromtext_warneof(isc_lex_t *lexer, dns_rdatacallbacks_t *callbacks);

static isc_result_t
rdata_totext(dns_rdata_t *rdata, dns_rdata_textctx_t *tctx,
         isc_buffer_t *target);

static inline isc_result_t
name_duporclone(dns_name_t *source, isc_mem_t *mctx, dns_name_t *target) {

    if (mctx != NULL)
        return (dns_name_dup(source, mctx, target));
    dns_name_clone(source, target);
    return (ISC_R_SUCCESS);
}

static inline void *
mem_maybedup(isc_mem_t *mctx, void *source, size_t length) {
    void *new;

    if (mctx == NULL)
        return (source);
    new = isc_mem_allocate(mctx, length);
    if (new != NULL)
        memcpy(new, source, length);

    return (new);
}

static const char hexdigits[] = "0123456789abcdef";
static const char decdigits[] = "0123456789";

#include "code.h"

#define META 0x0001
#define RESERVED 0x0002

#define RCODENAMES \
    /* standard rcodes */ \
    { dns_rcode_noerror, "NOERROR", 0}, \
    { dns_rcode_formerr, "FORMERR", 0}, \
    { dns_rcode_servfail, "SERVFAIL", 0}, \
    { dns_rcode_nxdomain, "NXDOMAIN", 0}, \
    { dns_rcode_notimp, "NOTIMP", 0}, \
    { dns_rcode_refused, "REFUSED", 0}, \
    { dns_rcode_yxdomain, "YXDOMAIN", 0}, \
    { dns_rcode_yxrrset, "YXRRSET", 0}, \
    { dns_rcode_nxrrset, "NXRRSET", 0}, \
    { dns_rcode_notauth, "NOTAUTH", 0}, \
    { dns_rcode_notzone, "NOTZONE", 0},

#define ERCODENAMES \
    /* extended rcodes */ \
    { dns_rcode_badvers, "BADVERS", 0}, \
    { 0, NULL, 0 }

#define TSIGRCODENAMES \
    /* extended rcodes */ \
    { dns_tsigerror_badsig, "BADSIG", 0}, \
    { dns_tsigerror_badkey, "BADKEY", 0}, \
    { dns_tsigerror_badtime, "BADTIME", 0}, \
    { dns_tsigerror_badmode, "BADMODE", 0}, \
    { dns_tsigerror_badname, "BADNAME", 0}, \
    { dns_tsigerror_badalg, "BADALG", 0}, \
    { 0, NULL, 0 }

/* RFC2538 section 2.1 */

#define CERTNAMES \
    { 1, "PKIX", 0}, \
    { 2, "SPKI", 0}, \
    { 3, "PGP", 0}, \
    { 253, "URI", 0}, \
    { 254, "OID", 0}, \
    { 0, NULL, 0}

/* RFC2535 section 7 */

#define SECALGNAMES \
    { 1, "RSAMD5", 0 }, \
    { 2, "DH", 0 }, \
    { 3, "DSA", 0 }, \
    { 4, "ECC", 0 }, \
    { 252, "INDIRECT", 0 }, \
    { 253, "PRIVATEDNS", 0 }, \
    { 254, "PRIVATEOID", 0 }, \
    { 0, NULL, 0}

/* RFC2535 section 7.1 */

#define SECPROTONAMES \
    {   0,    "NONE", 0 }, \
    {   1,    "TLS", 0 }, \
    {   2,    "EMAIL", 0 }, \
    {   3,    "DNSSEC", 0 }, \
    {   4,    "IPSEC", 0 }, \
    { 255,    "ALL", 0 }, \
    { 0, NULL, 0}

struct tbl {
    unsigned int    value;
    const char  *name;
    int     flags;
};

static struct tbl rcodes[] = { RCODENAMES ERCODENAMES };
static struct tbl tsigrcodes[] = { RCODENAMES TSIGRCODENAMES };
static struct tbl certs[] = { CERTNAMES };
static struct tbl secalgs[] = { SECALGNAMES };
static struct tbl secprotos[] = { SECPROTONAMES };

static struct keyflag {
    const char *name;
    unsigned int value;
    unsigned int mask;
} keyflags[] = {
    { "NOCONF", 0x4000, 0xC000 },
    { "NOAUTH", 0x8000, 0xC000 },
    { "NOKEY",  0xC000, 0xC000 },
    { "FLAG2",  0x2000, 0x2000 },
    { "EXTEND", 0x1000, 0x1000 },
    { "FLAG4",  0x0800, 0x0800 },
    { "FLAG5",  0x0400, 0x0400 },
    { "USER",   0x0000, 0x0300 },
    { "ZONE",   0x0100, 0x0300 },
    { "HOST",   0x0200, 0x0300 },
    { "NTYP3",  0x0300, 0x0300 },
    { "FLAG8",  0x0080, 0x0080 },
    { "FLAG9",  0x0040, 0x0040 },
    { "FLAG10", 0x0020, 0x0020 },
    { "FLAG11", 0x0010, 0x0010 },
    { "SIG0",   0x0000, 0x000F },
    { "SIG1",   0x0001, 0x000F },
    { "SIG2",   0x0002, 0x000F },
    { "SIG3",   0x0003, 0x000F },
    { "SIG4",   0x0004, 0x000F },
    { "SIG5",   0x0005, 0x000F },
    { "SIG6",   0x0006, 0x000F },
    { "SIG7",   0x0007, 0x000F },
    { "SIG8",   0x0008, 0x000F },
    { "SIG9",   0x0009, 0x000F },
    { "SIG10",  0x000A, 0x000F },
    { "SIG11",  0x000B, 0x000F },
    { "SIG12",  0x000C, 0x000F },
    { "SIG13",  0x000D, 0x000F },
    { "SIG14",  0x000E, 0x000F },
    { "SIG15",  0x000F, 0x000F },
    { NULL,     0, 0 }
};

/***
 *** Initialization
 ***/

void
dns_rdata_init(dns_rdata_t *rdata) {

    REQUIRE(rdata != NULL);

    rdata->data = NULL;
    rdata->length = 0;
    rdata->rdclass = 0;
    rdata->type = 0;
    rdata->flags = 0;
    ISC_LINK_INIT(rdata, link);
    /* ISC_LIST_INIT(rdata->list); */
}

#if 0
#define DNS_RDATA_INITIALIZED(rdata) \
    ((rdata)->data == NULL && (rdata)->length == 0 && \
     (rdata)->rdclass == 0 && (rdata)->type == 0 && (rdata)->flags == 0 && \
     !ISC_LINK_LINKED((rdata), link))
#else
#ifdef ISC_LIST_CHECKINIT
#define DNS_RDATA_INITIALIZED(rdata) \
    (!ISC_LINK_LINKED((rdata), link))
#else
#define DNS_RDATA_INITIALIZED(rdata) ISC_TRUE
#endif
#endif
#define DNS_RDATA_VALIDFLAGS(rdata) \
    (((rdata)->flags & ~DNS_RDATA_UPDATE) == 0)

void
dns_rdata_reset(dns_rdata_t *rdata) {

    REQUIRE(!ISC_LINK_LINKED(rdata, link));
    REQUIRE(DNS_RDATA_VALIDFLAGS(rdata));

    rdata->data = NULL;
    rdata->length = 0;
    rdata->rdclass = 0;
    rdata->type = 0;
    rdata->flags = 0;
}

/***
 ***
 ***/

void
dns_rdata_clone(const dns_rdata_t *src, dns_rdata_t *target) {

    REQUIRE(DNS_RDATA_INITIALIZED(target));

    REQUIRE(DNS_RDATA_VALIDFLAGS(src));
    REQUIRE(DNS_RDATA_VALIDFLAGS(target));

    target->data = src->data;
    target->length = src->length;
    target->rdclass = src->rdclass;
    target->type = src->type;
    target->flags = src->flags;
}


/***
 *** Comparisons
 ***/

int
dns_rdata_compare(const dns_rdata_t *rdata1, const dns_rdata_t *rdata2) {
    int result = 0;
    isc_boolean_t use_default = ISC_FALSE;

    REQUIRE(rdata1 != NULL);
    REQUIRE(rdata2 != NULL);
    REQUIRE(rdata1->data != NULL);
    REQUIRE(rdata2->data != NULL);
    REQUIRE(DNS_RDATA_VALIDFLAGS(rdata1));
    REQUIRE(DNS_RDATA_VALIDFLAGS(rdata2));

    if (rdata1->rdclass != rdata2->rdclass)
        return (rdata1->rdclass < rdata2->rdclass ? -1 : 1);

    if (rdata1->type != rdata2->type)
        return (rdata1->type < rdata2->type ? -1 : 1);

    COMPARESWITCH

    if (use_default) {
        isc_region_t r1;
        isc_region_t r2;

        dns_rdata_toregion(rdata1, &r1);
        dns_rdata_toregion(rdata2, &r2);
        result = compare_region(&r1, &r2);
    }
    return (result);
}

/***
 *** Conversions
 ***/

void
dns_rdata_fromregion(dns_rdata_t *rdata, dns_rdataclass_t rdclass,
             dns_rdatatype_t type, isc_region_t *r)
{

    REQUIRE(rdata != NULL);
    REQUIRE(DNS_RDATA_INITIALIZED(rdata));
    REQUIRE(r != NULL);

    REQUIRE(DNS_RDATA_VALIDFLAGS(rdata));

    rdata->data = r->base;
    rdata->length = r->length;
    rdata->rdclass = rdclass;
    rdata->type = type;
    rdata->flags = 0;
}

void
dns_rdata_toregion(const dns_rdata_t *rdata, isc_region_t *r) {

    REQUIRE(rdata != NULL);
    REQUIRE(r != NULL);
    REQUIRE(DNS_RDATA_VALIDFLAGS(rdata));

    r->base = rdata->data;
    r->length = rdata->length;
}

isc_result_t
dns_rdata_fromwire(dns_rdata_t *rdata, dns_rdataclass_t rdclass,
           dns_rdatatype_t type, isc_buffer_t *source,
           dns_decompress_t *dctx, isc_boolean_t downcase,
           isc_buffer_t *target)
{
    isc_result_t result = ISC_R_NOTIMPLEMENTED;
    isc_region_t region;
    isc_buffer_t ss;
    isc_buffer_t st;
    isc_boolean_t use_default = ISC_FALSE;
    isc_uint32_t activelength;

    REQUIRE(dctx != NULL);
    if (rdata != NULL) {
        REQUIRE(DNS_RDATA_INITIALIZED(rdata));
        REQUIRE(DNS_RDATA_VALIDFLAGS(rdata));
    }

    ss = *source;
    st = *target;

    activelength = isc_buffer_activelength(source);
    INSIST(activelength < 65536);

    FROMWIRESWITCH

    if (use_default) {
        if (activelength > isc_buffer_availablelength(target))
            result = ISC_R_NOSPACE;
        else {
            isc_buffer_putmem(target, isc_buffer_current(source),
                      activelength);
            isc_buffer_forward(source, activelength);
            result = ISC_R_SUCCESS;
        }
    }

    /*
     * We should have consumed all of our buffer.
     */
    if (result == ISC_R_SUCCESS && !buffer_empty(source))
        result = DNS_R_EXTRADATA;

    if (rdata != NULL && result == ISC_R_SUCCESS) {
        region.base = isc_buffer_used(&st);
        region.length = isc_buffer_usedlength(target) -
                isc_buffer_usedlength(&st);
        dns_rdata_fromregion(rdata, rdclass, type, &region);
    }

    if (result != ISC_R_SUCCESS) {
        *source = ss;
        *target = st;
    }
    return (result);
}

isc_result_t
dns_rdata_towire(dns_rdata_t *rdata, dns_compress_t *cctx,
         isc_buffer_t *target)
{
    isc_result_t result = ISC_R_NOTIMPLEMENTED;
    isc_boolean_t use_default = ISC_FALSE;
    isc_region_t tr;
    isc_buffer_t st;

    REQUIRE(rdata != NULL);
    REQUIRE(DNS_RDATA_VALIDFLAGS(rdata));

    /*
     * Some DynDNS meta-RRs have empty rdata.
     */
    if ((rdata->flags & DNS_RDATA_UPDATE) != 0) {
        INSIST(rdata->length == 0);
        return (ISC_R_SUCCESS);
    }

    st = *target;

    TOWIRESWITCH

    if (use_default) {
        isc_buffer_availableregion(target, &tr);
        if (tr.length < rdata->length)
            return (ISC_R_NOSPACE);
        memcpy(tr.base, rdata->data, rdata->length);
        isc_buffer_add(target, rdata->length);
        return (ISC_R_SUCCESS);
    }
    if (result != ISC_R_SUCCESS) {
        *target = st;
        INSIST(target->used < 65536);
        dns_compress_rollback(cctx, (isc_uint16_t)target->used);
    }
    return (result);
}

/*
 * If the binary data in 'src' is valid uncompressed wire format
 * rdata of class 'rdclass' and type 'type', return ISC_R_SUCCESS
 * and copy the validated rdata to 'dest'.  Otherwise return an error.
 */
static isc_result_t
rdata_validate(isc_buffer_t *src, isc_buffer_t *dest, dns_rdataclass_t rdclass,
        dns_rdatatype_t type)
{
    dns_decompress_t dctx;
    dns_rdata_t rdata = DNS_RDATA_INIT;
    isc_result_t result;

    dns_decompress_init(&dctx, -1, DNS_DECOMPRESS_NONE);
    isc_buffer_setactive(src, isc_buffer_usedlength(src));
    result = dns_rdata_fromwire(&rdata, rdclass, type, src,
                    &dctx, ISC_FALSE, dest);
    dns_decompress_invalidate(&dctx);

    return (result);
}

static isc_result_t
unknown_fromtext(dns_rdataclass_t rdclass, dns_rdatatype_t type,
         isc_lex_t *lexer, isc_mem_t *mctx, isc_buffer_t *target)
{
    isc_result_t result;
    isc_buffer_t *buf = NULL;
    isc_token_t token;

    if (dns_rdatatype_ismeta(type))
        return (DNS_R_METATYPE);

    result = isc_lex_getmastertoken(lexer, &token, isc_tokentype_number,
                    ISC_FALSE);
    if (result == ISC_R_SUCCESS && token.value.as_ulong > 65535)
        return (ISC_R_RANGE);
    result = isc_buffer_allocate(mctx, &buf, token.value.as_ulong);
    if (result != ISC_R_SUCCESS)
        return (result);

    result = isc_hex_tobuffer(lexer, buf,
                  (unsigned int)token.value.as_ulong);
    if (result != ISC_R_SUCCESS)
           goto failure;
    if (isc_buffer_usedlength(buf) != token.value.as_ulong) {
        result = ISC_R_UNEXPECTEDEND;
        goto failure;
    }

    if (dns_rdatatype_isknown(type)) {
        result = rdata_validate(buf, target, rdclass, type);
    } else {
        isc_region_t r;
        isc_buffer_usedregion(buf, &r);
        result = isc_buffer_copyregion(target, &r);
    }
    if (result != ISC_R_SUCCESS)
        goto failure;

    isc_buffer_free(&buf);
    return (ISC_R_SUCCESS);

 failure:
    isc_buffer_free(&buf);
    return (result);
}

isc_result_t
dns_rdata_fromtext(dns_rdata_t *rdata, dns_rdataclass_t rdclass,
           dns_rdatatype_t type, isc_lex_t *lexer,
           dns_name_t *origin, isc_boolean_t downcase, isc_mem_t *mctx,
           isc_buffer_t *target, dns_rdatacallbacks_t *callbacks)
{
    isc_result_t result = ISC_R_NOTIMPLEMENTED;
    isc_region_t region;
    isc_buffer_t st;
    isc_token_t token;
    unsigned int options = ISC_LEXOPT_EOL | ISC_LEXOPT_EOF |
                   ISC_LEXOPT_DNSMULTILINE | ISC_LEXOPT_ESCAPE;
    char *name;
    unsigned long line;
    void (*callback)(dns_rdatacallbacks_t *, const char *, ...);
    isc_result_t tresult;

    REQUIRE(origin == NULL || dns_name_isabsolute(origin) == ISC_TRUE);
    if (rdata != NULL) {
        REQUIRE(DNS_RDATA_INITIALIZED(rdata));
        REQUIRE(DNS_RDATA_VALIDFLAGS(rdata));
    }

    st = *target;

    if (callbacks == NULL)
        callback = NULL;
    else
        callback = callbacks->error;

    if (callback == NULL)
        callback = default_fromtext_callback;

    result = isc_lex_getmastertoken(lexer, &token, isc_tokentype_qstring,
                    ISC_FALSE);
    if (result != ISC_R_SUCCESS) {
        name = isc_lex_getsourcename(lexer);
        line = isc_lex_getsourceline(lexer);
        fromtext_error(callback, callbacks, name, line,
                   &token, result);
        return (result);
    }

    if (strcmp((char *)token.value.as_pointer, "\\#") == 0)
        result = unknown_fromtext(rdclass, type, lexer, mctx, target);
    else {
        isc_lex_ungettoken(lexer, &token);

        FROMTEXTSWITCH
    }

    /*
     * Consume to end of line / file.
     * If not at end of line initially set error code.
     * Call callback via fromtext_error once if there was an error.
     */
    do {
        name = isc_lex_getsourcename(lexer);
        line = isc_lex_getsourceline(lexer);
        tresult = isc_lex_gettoken(lexer, options, &token);
        if (tresult != ISC_R_SUCCESS) {
            if (result == ISC_R_SUCCESS)
                result = tresult;
            if (callback != NULL)
                fromtext_error(callback, callbacks, name,
                           line, NULL, result);
            break;
        } else if (token.type != isc_tokentype_eol &&
               token.type != isc_tokentype_eof) {
            if (result == ISC_R_SUCCESS)
                result = DNS_R_EXTRATOKEN;
            if (callback != NULL) {
                fromtext_error(callback, callbacks, name,
                           line, &token, result);
                callback = NULL;
            }
        } else if (result != ISC_R_SUCCESS && callback != NULL) {
            fromtext_error(callback, callbacks, name, line,
                       &token, result);
            break;
        } else {
            if (token.type == isc_tokentype_eof)
                fromtext_warneof(lexer, callbacks);
            break;
        }
    } while (1);

    if (rdata != NULL && result == ISC_R_SUCCESS) {
        region.base = isc_buffer_used(&st);
        region.length = isc_buffer_usedlength(target) -
                isc_buffer_usedlength(&st);
        dns_rdata_fromregion(rdata, rdclass, type, &region);
    }
    if (result != ISC_R_SUCCESS) {
        *target = st;
    }
    return (result);
}

static isc_result_t
rdata_totext(dns_rdata_t *rdata, dns_rdata_textctx_t *tctx,
         isc_buffer_t *target)
{
    isc_result_t result = ISC_R_NOTIMPLEMENTED;
    isc_boolean_t use_default = ISC_FALSE;
    char buf[sizeof "65536"];
    isc_region_t sr;

    REQUIRE(rdata != NULL);
    REQUIRE(tctx->origin == NULL ||
        dns_name_isabsolute(tctx->origin) == ISC_TRUE);

    /*
     * Some DynDNS meta-RRs have empty rdata.
     */
    if ((rdata->flags & DNS_RDATA_UPDATE) != 0) {
        INSIST(rdata->length == 0);
        return (ISC_R_SUCCESS);
    }

    TOTEXTSWITCH

    if (use_default) {
        sprintf(buf, "\\# ");
        result = str_totext(buf, target);
        dns_rdata_toregion(rdata, &sr);
        INSIST(sr.length < 65536);
        sprintf(buf, "%u", sr.length);
        result = str_totext(buf, target);
        if (sr.length != 0 && result == ISC_R_SUCCESS) {
            if ((tctx->flags & DNS_STYLEFLAG_MULTILINE) != 0)
                result = str_totext(" ( ", target);
            else
                result = str_totext(" ", target);
            if (result == ISC_R_SUCCESS)
                result = isc_hex_totext(&sr, tctx->width - 2,
                            tctx->linebreak,
                            target);
            if (result == ISC_R_SUCCESS &&
                (tctx->flags & DNS_STYLEFLAG_MULTILINE) != 0)
                result = str_totext(" )", target);
        }
    }

    return (result);
}

isc_result_t
dns_rdata_totext(dns_rdata_t *rdata, dns_name_t *origin, isc_buffer_t *target)
{
    dns_rdata_textctx_t tctx;

    REQUIRE(DNS_RDATA_VALIDFLAGS(rdata));

    /*
     * Set up formatting options for single-line output.
     */
    tctx.origin = origin;
    tctx.flags = 0;
    tctx.width = 60;
    tctx.linebreak = " ";
    return (rdata_totext(rdata, &tctx, target));
}

isc_result_t
dns_rdata_tofmttext(dns_rdata_t *rdata, dns_name_t *origin,
            unsigned int flags, unsigned int width,
            char *linebreak, isc_buffer_t *target)
{
    dns_rdata_textctx_t tctx;

    REQUIRE(DNS_RDATA_VALIDFLAGS(rdata));

    /*
     * Set up formatting options for formatted output.
     */
    tctx.origin = origin;
    tctx.flags = flags;
    if ((flags & DNS_STYLEFLAG_MULTILINE) != 0) {
        tctx.width = width;
        tctx.linebreak = linebreak;
    } else {
        tctx.width = 60; /* Used for hex word length only. */
        tctx.linebreak = " ";
    }
    return (rdata_totext(rdata, &tctx, target));
}

isc_result_t
dns_rdata_fromstruct(dns_rdata_t *rdata, dns_rdataclass_t rdclass,
             dns_rdatatype_t type, void *source,
             isc_buffer_t *target)
{
    isc_result_t result = ISC_R_NOTIMPLEMENTED;
    isc_buffer_t st;
    isc_region_t region;
    isc_boolean_t use_default = ISC_FALSE;

    REQUIRE(source != NULL);
    if (rdata != NULL) {
        REQUIRE(DNS_RDATA_INITIALIZED(rdata));
        REQUIRE(DNS_RDATA_VALIDFLAGS(rdata));
    }

    st = *target;

    FROMSTRUCTSWITCH

    if (use_default)
        (void)NULL;

    if (rdata != NULL && result == ISC_R_SUCCESS) {
        region.base = isc_buffer_used(&st);
        region.length = isc_buffer_usedlength(target) -
                isc_buffer_usedlength(&st);
        dns_rdata_fromregion(rdata, rdclass, type, &region);
    }
    if (result != ISC_R_SUCCESS)
        *target = st;
    return (result);
}

isc_result_t
dns_rdata_tostruct(dns_rdata_t *rdata, void *target, isc_mem_t *mctx) {
    isc_result_t result = ISC_R_NOTIMPLEMENTED;
    isc_boolean_t use_default = ISC_FALSE;

    REQUIRE(rdata != NULL);
    REQUIRE(DNS_RDATA_VALIDFLAGS(rdata));

    TOSTRUCTSWITCH

    if (use_default)
        (void)NULL;

    return (result);
}

void
dns_rdata_freestruct(void *source) {
    dns_rdatacommon_t *common = source;
    REQUIRE(source != NULL);

    FREESTRUCTSWITCH
}

isc_result_t
dns_rdata_additionaldata(dns_rdata_t *rdata, dns_additionaldatafunc_t add,
             void *arg)
{
    isc_result_t result = ISC_R_NOTIMPLEMENTED;
    isc_boolean_t use_default = ISC_FALSE;

    /*
     * Call 'add' for each name and type from 'rdata' which is subject to
     * additional section processing.
     */

    REQUIRE(rdata != NULL);
    REQUIRE(add != NULL);
    REQUIRE(DNS_RDATA_VALIDFLAGS(rdata));

    ADDITIONALDATASWITCH

    /* No additional processing for unknown types */
    if (use_default)
        result = ISC_R_SUCCESS;

    return (result);
}

isc_result_t
dns_rdata_digest(dns_rdata_t *rdata, dns_digestfunc_t digest, void *arg) {
    isc_result_t result = ISC_R_NOTIMPLEMENTED;
    isc_boolean_t use_default = ISC_FALSE;
    isc_region_t r;

    /*
     * Send 'rdata' in DNSSEC canonical form to 'digest'.
     */

    REQUIRE(rdata != NULL);
    REQUIRE(digest != NULL);
    REQUIRE(DNS_RDATA_VALIDFLAGS(rdata));

    DIGESTSWITCH

    if (use_default) {
        dns_rdata_toregion(rdata, &r);
        result = (digest)(arg, &r);
    }

    return (result);
}

unsigned int
dns_rdatatype_attributes(dns_rdatatype_t type)
{
    if (type > 255)
        return (DNS_RDATATYPEATTR_UNKNOWN);

    return (typeattr[type].flags);
}

#define NUMBERSIZE sizeof("037777777777") /* 2^32-1 octal + NUL */

static isc_result_t
dns_mnemonic_fromtext(unsigned int *valuep, isc_textregion_t *source,
              struct tbl *table, unsigned int max)
{
    int i;

    if (isdigit(source->base[0] & 0xff) &&
        source->length <= NUMBERSIZE - 1) {
        unsigned int n;
        char *e;
        char buffer[NUMBERSIZE];
        /*
         * We have a potential number.  Try to parse it with strtoul().
         * strtoul() requires null termination, so we must make
         * a copy.
         */
        strncpy(buffer, source->base, NUMBERSIZE);
        INSIST(buffer[source->length] == '\0');

        n = strtoul(buffer, &e, 10);
        if (*e == 0) {
            if (n > max)
                return (ISC_R_RANGE);
            *valuep = n;
            return (ISC_R_SUCCESS);
        }
        /*
         * It was not a number after all; fall through.
         */
    }

    for (i = 0; table[i].name != NULL; i++) {
        unsigned int n;
        n = strlen(table[i].name);
        if (n == source->length &&
            strncasecmp(source->base, table[i].name, n) == 0) {
            *valuep = table[i].value;
            return (ISC_R_SUCCESS);
        }
    }
    return (DNS_R_UNKNOWN);
}

static isc_result_t
dns_mnemonic_totext(unsigned int value, isc_buffer_t *target,
            struct tbl *table)
{
    int i = 0;
    char buf[sizeof "4294967296"];
    while (table[i].name != NULL) {
        if (table[i].value == value) {
            return (str_totext(table[i].name, target));
        }
        i++;
    }
    sprintf(buf, "%u", value);
    return (str_totext(buf, target));
}


/*
 * This uses lots of hard coded values, but how often do we actually
 * add classes?
 */
isc_result_t
dns_rdataclass_fromtext(dns_rdataclass_t *classp, isc_textregion_t *source) {
#define COMPARE(string, rdclass) \
    if (((sizeof(string) - 1) == source->length) \
        && (strcasecmp(source->base, string) == 0)) { \
        *classp = rdclass; \
        return (ISC_R_SUCCESS); \
    }

    switch (tolower((unsigned char)source->base[0])) {
    case 'a':
        COMPARE("any", dns_rdataclass_any);
        break;
    case 'c':
        /*
         * RFC1035 says the mnemonic for the CHAOS class is CH,
         * but historical BIND practice is to call it CHAOS.
         * We will accept both forms, but only generate CH.
         */
        COMPARE("ch", dns_rdataclass_chaos);
        COMPARE("chaos", dns_rdataclass_chaos);
        if (source->length > 5 &&
            strncasecmp("class", source->base, 5) == 0)
        {
            char *endp;
            int val = strtol(source->base + 5, &endp, 10);
            if (*endp == '\0' && val >= 0 && val <= 0xffff) {
                *classp = (dns_rdataclass_t)val;
                return (ISC_R_SUCCESS);
            }
        }
        break;
    case 'h':
        COMPARE("hs", dns_rdataclass_hs);
        break;
    case 'i':
        COMPARE("in", dns_rdataclass_in);
        break;
    case 'n':
        COMPARE("none", dns_rdataclass_none);
        break;
    case 'r':
        COMPARE("reserved0", dns_rdataclass_reserved0);
        break;
    }

#undef COMPARE

    return (DNS_R_UNKNOWN);
}

isc_result_t
dns_rdataclass_totext(dns_rdataclass_t rdclass, isc_buffer_t *target) {
    char buf[sizeof("CLASS65536")];

    switch (rdclass) {
    case dns_rdataclass_any:
        return (str_totext("ANY", target));
    case dns_rdataclass_chaos:
        return (str_totext("CH", target));
    case dns_rdataclass_hs:
        return (str_totext("HS", target));
    case dns_rdataclass_in:
        return (str_totext("IN", target));
    case dns_rdataclass_none:
        return (str_totext("NONE", target));
    case dns_rdataclass_reserved0:
        return (str_totext("RESERVED0", target));
    default:
        sprintf(buf, "CLASS%u", rdclass);
        return (str_totext(buf, target));
    }
}

void
dns_rdataclass_format(dns_rdataclass_t rdclass,
              char *array, unsigned int size)
{
    isc_result_t result;
    isc_buffer_t buf;

    isc_buffer_init(&buf, array, size);
    result = dns_rdataclass_totext(rdclass, &buf);
    /*
     * Null terminate.
     */
    if (result == ISC_R_SUCCESS) {
        if (isc_buffer_availablelength(&buf) >= 1)
            isc_buffer_putuint8(&buf, 0);
        else
            result = ISC_R_NOSPACE;
    }
    if (result != ISC_R_SUCCESS) {
        snprintf(array, size, "<unknown>");
        array[size - 1] = '\0';
    }
}

isc_result_t
dns_rdatatype_fromtext(dns_rdatatype_t *typep, isc_textregion_t *source) {
    unsigned int hash;
    unsigned int n;
    unsigned char a, b;

    n = source->length;

    if (n == 0)
        return (DNS_R_UNKNOWN);

    a = tolower((unsigned char)source->base[0]);
    b = tolower((unsigned char)source->base[n - 1]);

    hash = ((a + n) * b) % 256;

    /*
     * This switch block is inlined via #define, and will use "return"
     * to return a result to the caller if it is a valid (known)
     * rdatatype name.
     */
    RDATATYPE_FROMTEXT_SW(hash, source->base, typep);

    if (source->length > 4 && strncasecmp("type", source->base, 4) == 0) {
        char *endp;
        int val = strtol(source->base + 4, &endp, 10);
        if (*endp == '\0' && val >= 0 && val <= 0xffff) {
            *typep = (dns_rdatatype_t)val;
            return (ISC_R_SUCCESS);
        }
    }

    return (DNS_R_UNKNOWN);
}

isc_result_t
dns_rdatatype_totext(dns_rdatatype_t type, isc_buffer_t *target) {
    char buf[sizeof "TYPE65536"];

    if (type > 255) {
        sprintf(buf, "TYPE%u", type);
        return (str_totext(buf, target));
    }

    return (str_totext(typeattr[type].name, target));
}

void
dns_rdatatype_format(dns_rdatatype_t rdtype,
             char *array, unsigned int size)
{
    isc_result_t result;
    isc_buffer_t buf;

    isc_buffer_init(&buf, array, size);
    result = dns_rdatatype_totext(rdtype, &buf);
    /*
     * Null terminate.
     */
    if (result == ISC_R_SUCCESS) {
        if (isc_buffer_availablelength(&buf) >= 1)
            isc_buffer_putuint8(&buf, 0);
        else
            result = ISC_R_NOSPACE;
    }
    if (result != ISC_R_SUCCESS) {
        snprintf(array, size, "<unknown>");
        array[size - 1] = '\0';
    }
}


/* XXXRTH  Should we use a hash table here? */

isc_result_t
dns_rcode_fromtext(dns_rcode_t *rcodep, isc_textregion_t *source) {
    unsigned int value;
    RETERR(dns_mnemonic_fromtext(&value, source, rcodes, 0xffff));
    *rcodep = value;
    return (ISC_R_SUCCESS);
}

isc_result_t
dns_rcode_totext(dns_rcode_t rcode, isc_buffer_t *target) {
    return (dns_mnemonic_totext(rcode, target, rcodes));
}

isc_result_t
dns_tsigrcode_fromtext(dns_rcode_t *rcodep, isc_textregion_t *source) {
    unsigned int value;
    RETERR(dns_mnemonic_fromtext(&value, source, tsigrcodes, 0xffff));
    *rcodep = value;
    return (ISC_R_SUCCESS);
}

isc_result_t
dns_tsigrcode_totext(dns_rcode_t rcode, isc_buffer_t *target) {
    return (dns_mnemonic_totext(rcode, target, tsigrcodes));
}

isc_result_t
dns_cert_fromtext(dns_cert_t *certp, isc_textregion_t *source) {
    unsigned int value;
    RETERR(dns_mnemonic_fromtext(&value, source, certs, 0xffff));
    *certp = value;
    return (ISC_R_SUCCESS);
}

isc_result_t
dns_cert_totext(dns_cert_t cert, isc_buffer_t *target) {
    return (dns_mnemonic_totext(cert, target, certs));
}

isc_result_t
dns_secalg_fromtext(dns_secalg_t *secalgp, isc_textregion_t *source) {
    unsigned int value;
    RETERR(dns_mnemonic_fromtext(&value, source, secalgs, 0xff));
    *secalgp = value;
    return (ISC_R_SUCCESS);
}

isc_result_t
dns_secalg_totext(dns_secalg_t secalg, isc_buffer_t *target) {
    return (dns_mnemonic_totext(secalg, target, secalgs));
}

isc_result_t
dns_secproto_fromtext(dns_secproto_t *secprotop, isc_textregion_t *source) {
    unsigned int value;
    RETERR(dns_mnemonic_fromtext(&value, source, secprotos, 0xff));
    *secprotop = value;
    return (ISC_R_SUCCESS);
}

isc_result_t
dns_secproto_totext(dns_secproto_t secproto, isc_buffer_t *target) {
    return (dns_mnemonic_totext(secproto, target, secprotos));
}

isc_result_t
dns_keyflags_fromtext(dns_keyflags_t *flagsp, isc_textregion_t *source)
{
    char *text, *end;
    unsigned int value, mask;

    if (isdigit(source->base[0] & 0xff) &&
        source->length <= NUMBERSIZE - 1) {
        unsigned int n;
        char *e;
        char buffer[NUMBERSIZE];
        /*
         * We have a potential number.  Try to parse it with strtoul().
         * strtoul() requires null termination, so we must make
         * a copy.
         */
        strncpy(buffer, source->base, NUMBERSIZE);
        INSIST(buffer[source->length] == '\0');

        n = strtoul(buffer, &e, 0); /* Allow hex/octal. */
        if (*e == 0) {
            if (n > 0xffff)
                return (ISC_R_RANGE);
            *flagsp = n;
            return (ISC_R_SUCCESS);
        }
        /* It was not a number after all; fall through. */
    }

    text = source->base;
    end = source->base + source->length;
    value = mask = 0;

    while (text < end) {
        struct keyflag *p;
        unsigned int len;
        char *delim = memchr(text, '|', end - text);
        if (delim != NULL)
            len = delim - text;
        else
            len = end - text;
        for (p = keyflags; p->name != NULL; p++) {
            if (strncasecmp(p->name, text, len) == 0)
                break;
        }
        if (p->name == NULL)
            return (DNS_R_UNKNOWN);
        value |= p->value;
#ifdef notyet
        if ((mask & p->mask) != 0)
            warn("overlapping key flags");
#endif
        mask |= p->mask;
        text += len;
        if (delim != NULL)
            text++; /* Skip "|" */
    }
    *flagsp = value;
    return (ISC_R_SUCCESS);
}

/*
 * Private function.
 */

static unsigned int
name_length(dns_name_t *name) {
    return (name->length);
}

static isc_result_t
txt_totext(isc_region_t *source, isc_buffer_t *target) {
    unsigned int tl;
    unsigned int n;
    unsigned char *sp;
    char *tp;
    isc_region_t region;

    isc_buffer_availableregion(target, &region);
    sp = source->base;
    tp = (char *)region.base;
    tl = region.length;

    n = *sp++;

    REQUIRE(n + 1 <= source->length);

    if (tl < 1)
        return (ISC_R_NOSPACE);
    *tp++ = '"';
    tl--;
    while (n--) {
        if (*sp < 0x20 || *sp >= 0x7f) {
            if (tl < 4)
                return (ISC_R_NOSPACE);
            sprintf(tp, "\\%03u", *sp++);
            tp += 4;
            tl -= 4;
            continue;
        }
        if (*sp == 0x22 || *sp == 0x3b || *sp == 0x5c) {
            if (tl < 2)
                return (ISC_R_NOSPACE);
            *tp++ = '\\';
            tl--;
        }
        if (tl < 1)
            return (ISC_R_NOSPACE);
        *tp++ = *sp++;
        tl--;
    }
    if (tl < 1)
        return (ISC_R_NOSPACE);
    *tp++ = '"';
    tl--;
    isc_buffer_add(target, tp - (char *)region.base);
    isc_region_consume(source, *source->base + 1);
    return (ISC_R_SUCCESS);
}

static isc_result_t
txt_fromtext(isc_textregion_t *source, isc_buffer_t *target) {
    isc_region_t tregion;
    isc_boolean_t escape;
    unsigned int n, nrem;
    char *s;
    unsigned char *t;
    int d;
    int c;

    isc_buffer_availableregion(target, &tregion);
    s = source->base;
    n = source->length;
    t = tregion.base;
    nrem = tregion.length;
    escape = ISC_FALSE;
    if (nrem < 1)
        return (ISC_R_NOSPACE);
    /*
     * Length byte.
     */
    nrem--;
    t++;
    /*
     * Maximum text string length.
     */
    if (nrem > 255)
        nrem = 255;
    while (n-- != 0) {
        c = (*s++)&0xff;
        if (escape && (d = decvalue((char)c)) != -1) {
            c = d;
            if (n == 0)
                return (DNS_R_SYNTAX);
            n--;
            if ((d = decvalue(*s++)) != -1)
                c = c * 10 + d;
            else
                return (DNS_R_SYNTAX);
            if (n == 0)
                return (DNS_R_SYNTAX);
            n--;
            if ((d = decvalue(*s++)) != -1)
                c = c * 10 + d;
            else
                return (DNS_R_SYNTAX);
            if (c > 255)
                return (DNS_R_SYNTAX);
        } else if (!escape && c == '\\') {
            escape = ISC_TRUE;
            continue;
        }
        escape = ISC_FALSE;
        if (nrem == 0)
            return (ISC_R_NOSPACE);
        *t++ = c;
        nrem--;
    }
    if (escape)
        return (DNS_R_SYNTAX);
    *tregion.base = t - tregion.base - 1;
    isc_buffer_add(target, *tregion.base + 1);
    return (ISC_R_SUCCESS);
}

static isc_result_t
txt_fromwire(isc_buffer_t *source, isc_buffer_t *target) {
    unsigned int n;
    isc_region_t sregion;
    isc_region_t tregion;

    isc_buffer_activeregion(source, &sregion);
    if (sregion.length == 0)
        return(ISC_R_UNEXPECTEDEND);
    n = *sregion.base + 1;
    if (n > sregion.length)
        return (ISC_R_UNEXPECTEDEND);

    isc_buffer_availableregion(target, &tregion);
    if (n > tregion.length)
        return (ISC_R_NOSPACE);

    memcpy(tregion.base, sregion.base, n);
    isc_buffer_forward(source, n);
    isc_buffer_add(target, n);
    return (ISC_R_SUCCESS);
}

static isc_boolean_t
name_prefix(dns_name_t *name, dns_name_t *origin, dns_name_t *target) {
    int l1, l2;

    if (origin == NULL)
        goto return_false;

    if (dns_name_compare(origin, dns_rootname) == 0)
        goto return_false;

    if (!dns_name_issubdomain(name, origin))
        goto return_false;

    l1 = dns_name_countlabels(name);
    l2 = dns_name_countlabels(origin);

    if (l1 == l2)
        goto return_false;

    dns_name_getlabelsequence(name, 0, l1 - l2, target);
    return (ISC_TRUE);

return_false:
    *target = *name;
    return (ISC_FALSE);
}

static isc_result_t
str_totext(const char *source, isc_buffer_t *target) {
    unsigned int l;
    isc_region_t region;

    isc_buffer_availableregion(target, &region);
    l = strlen(source);

    if (l > region.length)
        return (ISC_R_NOSPACE);

    memcpy(region.base, source, l);
    isc_buffer_add(target, l);
    return (ISC_R_SUCCESS);
}

static isc_boolean_t
buffer_empty(isc_buffer_t *source) {
    return((source->current == source->active) ? ISC_TRUE : ISC_FALSE);
}

static void
buffer_fromregion(isc_buffer_t *buffer, isc_region_t *region) {
    isc_buffer_init(buffer, region->base, region->length);
    isc_buffer_add(buffer, region->length);
    isc_buffer_setactive(buffer, region->length);
}

static isc_result_t
uint32_tobuffer(isc_uint32_t value, isc_buffer_t *target) {
    isc_region_t region;

    isc_buffer_availableregion(target, &region);
    if (region.length < 4)
        return (ISC_R_NOSPACE);
    isc_buffer_putuint32(target, value);
    return (ISC_R_SUCCESS);
}

static isc_result_t
uint16_tobuffer(isc_uint32_t value, isc_buffer_t *target) {
    isc_region_t region;

    if (value > 0xffff)
        return (ISC_R_RANGE);
    isc_buffer_availableregion(target, &region);
    if (region.length < 2)
        return (ISC_R_NOSPACE);
    isc_buffer_putuint16(target, (isc_uint16_t)value);
    return (ISC_R_SUCCESS);
}

static isc_result_t
uint8_tobuffer(isc_uint32_t value, isc_buffer_t *target) {
    isc_region_t region;

    if (value > 0xff)
        return (ISC_R_RANGE);
    isc_buffer_availableregion(target, &region);
    if (region.length < 1)
        return (ISC_R_NOSPACE);
    isc_buffer_putuint8(target, (isc_uint8_t)value);
    return (ISC_R_SUCCESS);
}

static isc_result_t
name_tobuffer(dns_name_t *name, isc_buffer_t *target) {
    isc_region_t r;
    dns_name_toregion(name, &r);
    return (isc_buffer_copyregion(target, &r));
}

static isc_uint32_t
uint32_fromregion(isc_region_t *region) {
    unsigned long value;

    REQUIRE(region->length >= 4);
    value = region->base[0] << 24;
    value |= region->base[1] << 16;
    value |= region->base[2] << 8;
    value |= region->base[3];
    return(value);
}

static isc_uint16_t
uint16_fromregion(isc_region_t *region) {

    REQUIRE(region->length >= 2);

    return ((region->base[0] << 8) | region->base[1]);
}

static isc_uint8_t
uint8_fromregion(isc_region_t *region) {

    REQUIRE(region->length >= 1);

    return (region->base[0]);
}

static isc_result_t
mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length) {
    isc_region_t tr;

    isc_buffer_availableregion(target, &tr);
    if (length > tr.length)
        return (ISC_R_NOSPACE);
    memcpy(tr.base, base, length);
    isc_buffer_add(target, length);
    return (ISC_R_SUCCESS);
}

static int
compare_region(isc_region_t *r1, isc_region_t *r2) {
    unsigned int l;
    int result;

    l = (r1->length < r2->length) ? r1->length : r2->length;

    if ((result = memcmp(r1->base, r2->base, l)) != 0)
        return ((result < 0) ? -1 : 1);
    else
        return ((r1->length == r2->length) ? 0 :
            (r1->length < r2->length) ? -1 : 1);
}

static int
hexvalue(char value) {
    char *s;
    unsigned char c;

    c = (unsigned char)value;

    if (!isascii(c))
        return (-1);
    if (isupper(c))
        c = tolower(c);
    if ((s = strchr(hexdigits, value)) == NULL)
        return (-1);
    return (s - hexdigits);
}

static int
decvalue(char value) {
    char *s;

    /*
     * isascii() is valid for full range of int values, no need to
     * mask or cast.
     */
    if (!isascii(value))
        return (-1);
    if ((s = strchr(decdigits, value)) == NULL)
        return (-1);
    return (s - decdigits);
}

static const char atob_digits[86] =
    "!\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`" \
    "abcdefghijklmnopqrstu";
/*
 * Subroutines to convert between 8 bit binary bytes and printable ASCII.
 * Computes the number of bytes, and three kinds of simple checksums.
 * Incoming bytes are collected into 32-bit words, then printed in base 85:
 *  exp(85,5) > exp(2,32)
 * The ASCII characters used are between '!' and 'u';
 * 'z' encodes 32-bit zero; 'x' is used to mark the end of encoded data.
 *
 * Originally by Paul Rutter (philabs!per) and Joe Orost (petsd!joe) for
 * the atob/btoa programs, released with the compress program, in mod.sources.
 * Modified by Mike Schwartz 8/19/86 for use in BIND.
 * Modified to be re-entrant 3/2/99.
 */


struct state {
    isc_int32_t Ceor;
    isc_int32_t Csum;
    isc_int32_t Crot;
    isc_int32_t word;
    isc_int32_t bcount;
};

#define Ceor state->Ceor
#define Csum state->Csum
#define Crot state->Crot
#define word state->word
#define bcount state->bcount

#define times85(x)  ((((((x<<2)+x)<<2)+x)<<2)+x)

static isc_result_t byte_atob(int c, isc_buffer_t *target,
                  struct state *state);
static isc_result_t putbyte(int c, isc_buffer_t *, struct state *state);
static isc_result_t byte_btoa(int c, isc_buffer_t *, struct state *state);

/*
 * Decode ASCII-encoded byte c into binary representation and
 * place into *bufp, advancing bufp.
 */
static isc_result_t
byte_atob(int c, isc_buffer_t *target, struct state *state) {
    char *s;
    if (c == 'z') {
        if (bcount != 0)
            return(DNS_R_SYNTAX);
        else {
            RETERR(putbyte(0, target, state));
            RETERR(putbyte(0, target, state));
            RETERR(putbyte(0, target, state));
            RETERR(putbyte(0, target, state));
        }
    } else if ((s = strchr(atob_digits, c)) != NULL) {
        if (bcount == 0) {
            word = s - atob_digits;
            ++bcount;
        } else if (bcount < 4) {
            word = times85(word);
            word += s - atob_digits;
            ++bcount;
        } else {
            word = times85(word);
            word += s - atob_digits;
            RETERR(putbyte((word >> 24) & 0xff, target, state));
            RETERR(putbyte((word >> 16) & 0xff, target, state));
            RETERR(putbyte((word >> 8) & 0xff, target, state));
            RETERR(putbyte(word & 0xff, target, state));
            word = 0;
            bcount = 0;
        }
    } else
        return(DNS_R_SYNTAX);
    return(ISC_R_SUCCESS);
}

/*
 * Compute checksum info and place c into target.
 */
static isc_result_t
putbyte(int c, isc_buffer_t *target, struct state *state) {
    isc_region_t tr;

    Ceor ^= c;
    Csum += c;
    Csum += 1;
    if ((Crot & 0x80000000)) {
        Crot <<= 1;
        Crot += 1;
    } else {
        Crot <<= 1;
    }
    Crot += c;
    isc_buffer_availableregion(target, &tr);
    if (tr.length < 1)
        return (ISC_R_NOSPACE);
    tr.base[0] = c;
    isc_buffer_add(target, 1);
    return (ISC_R_SUCCESS);
}

/*
 * Read the ASCII-encoded data from inbuf, of length inbuflen, and convert
 * it into T_UNSPEC (binary data) in outbuf, not to exceed outbuflen bytes;
 * outbuflen must be divisible by 4.  (Note: this is because outbuf is filled
 * in 4 bytes at a time.  If the actual data doesn't end on an even 4-byte
 * boundary, there will be no problem...it will be padded with 0 bytes, and
 * numbytes will indicate the correct number of bytes.  The main point is
 * that since the buffer is filled in 4 bytes at a time, even if there is
 * not a full 4 bytes of data at the end, there has to be room to 0-pad the
 * data, so the buffer must be of size divisible by 4).  Place the number of
 * output bytes in numbytes, and return a failure/success status.
 */

static isc_result_t
atob_tobuffer(isc_lex_t *lexer, isc_buffer_t *target) {
    long oeor, osum, orot;
    struct state statebuf, *state= &statebuf;
    isc_token_t token;
    char c;
    char *e;

    Ceor = Csum = Crot = word = bcount = 0;

    RETERR(isc_lex_getmastertoken(lexer, &token, isc_tokentype_string,
                      ISC_FALSE));
    while (token.value.as_textregion.length != 0) {
        if ((c = token.value.as_textregion.base[0]) == 'x') {
            break;
        } else
            RETERR(byte_atob(c, target, state));
        isc_textregion_consume(&token.value.as_textregion, 1);
    }

    /*
     * Number of bytes.
     */
    RETERR(isc_lex_getmastertoken(lexer, &token, isc_tokentype_number,
                      ISC_FALSE));
    if ((token.value.as_ulong % 4) != 0)
        isc_buffer_subtract(target,  4 - (token.value.as_ulong % 4));

    /*
     * Checksum.
     */
    RETERR(isc_lex_getmastertoken(lexer, &token, isc_tokentype_string,
                      ISC_FALSE));
    oeor = strtol(token.value.as_pointer, &e, 16);
    if (*e != 0)
        return (DNS_R_SYNTAX);

    /*
     * Checksum.
     */
    RETERR(isc_lex_getmastertoken(lexer, &token, isc_tokentype_string,
                      ISC_FALSE));
    osum = strtol(token.value.as_pointer, &e, 16);
    if (*e != 0)
        return (DNS_R_SYNTAX);

    /*
     * Checksum.
     */
    RETERR(isc_lex_getmastertoken(lexer, &token, isc_tokentype_string,
                      ISC_FALSE));
    orot = strtol(token.value.as_pointer, &e, 16);
    if (*e != 0)
        return (DNS_R_SYNTAX);

    if ((oeor != Ceor) || (osum != Csum) || (orot != Crot))
        return(DNS_R_BADCKSUM);
    return (ISC_R_SUCCESS);
}

/*
 * Encode binary byte c into ASCII representation and place into *bufp,
 * advancing bufp.
 */
static isc_result_t
byte_btoa(int c, isc_buffer_t *target, struct state *state) {
    isc_region_t tr;

    isc_buffer_availableregion(target, &tr);
    Ceor ^= c;
    Csum += c;
    Csum += 1;
    if ((Crot & 0x80000000)) {
        Crot <<= 1;
        Crot += 1;
    } else {
        Crot <<= 1;
    }
    Crot += c;

    word <<= 8;
    word |= c;
    if (bcount == 3) {
        if (word == 0) {
            if (tr.length < 1)
                return (ISC_R_NOSPACE);
            tr.base[0] = 'z';
            isc_buffer_add(target, 1);
        } else {
            register int tmp = 0;
            register isc_int32_t tmpword = word;

            if (tmpword < 0) {
               /*
                * Because some don't support u_long.
                */
                tmp = 32;
                tmpword -= (isc_int32_t)(85 * 85 * 85 * 85 * 32);
            }
            if (tmpword < 0) {
                tmp = 64;
                tmpword -= (isc_int32_t)(85 * 85 * 85 * 85 * 32);
            }
            if (tr.length < 5)
                return (ISC_R_NOSPACE);
                tr.base[0] = atob_digits[(tmpword /
                          (isc_int32_t)(85 * 85 * 85 * 85))
                        + tmp];
            tmpword %= (isc_int32_t)(85 * 85 * 85 * 85);
            tr.base[1] = atob_digits[tmpword / (85 * 85 * 85)];
            tmpword %= (85 * 85 * 85);
            tr.base[2] = atob_digits[tmpword / (85 * 85)];
            tmpword %= (85 * 85);
            tr.base[3] = atob_digits[tmpword / 85];
            tmpword %= 85;
            tr.base[4] = atob_digits[tmpword];
            isc_buffer_add(target, 5);
        }
        bcount = 0;
    } else {
        bcount += 1;
    }
    return (ISC_R_SUCCESS);
}


/*
 * Encode the binary data from inbuf, of length inbuflen, into a
 * target.  Return success/failure status
 */
static isc_result_t
btoa_totext(unsigned char *inbuf, int inbuflen, isc_buffer_t *target) {
    int inc;
    struct state statebuf, *state = &statebuf;
    char buf[sizeof "x 2000000000 ffffffff ffffffff ffffffff"];

    Ceor = Csum = Crot = word = bcount = 0;
    for (inc = 0; inc < inbuflen; inbuf++, inc++)
        RETERR(byte_btoa(*inbuf, target, state));

    while (bcount != 0)
        RETERR(byte_btoa(0, target, state));

    /*
     * Put byte count and checksum information at end of buffer,
     * delimited by 'x'
     */
    sprintf(buf, "x %d %x %x %x", inbuflen, Ceor, Csum, Crot);
    return (str_totext(buf, target));
}


static void
default_fromtext_callback(dns_rdatacallbacks_t *callbacks, const char *fmt,
              ...)
{
    va_list ap;

    UNUSED(callbacks);

    va_start(ap, fmt);
    vfprintf(stderr, fmt, ap);
    va_end(ap);
}

static void
fromtext_warneof(isc_lex_t *lexer, dns_rdatacallbacks_t *callbacks) {
    if (isc_lex_isfile(lexer) && callbacks != NULL)
        (*callbacks->warn)(callbacks,
                   "%s:%lu: file does not end with newline",
                    isc_lex_getsourcename(lexer),
                    isc_lex_getsourceline(lexer));
}

static void
fromtext_error(void (*callback)(dns_rdatacallbacks_t *, const char *, ...),
           dns_rdatacallbacks_t *callbacks, const char *name,
           unsigned long line, isc_token_t *token, isc_result_t result)
{
    if (name == NULL)
        name = "UNKNOWN";

    if (token != NULL) {
        switch (token->type) {
        case isc_tokentype_eol:
            (*callback)(callbacks, "%s: %s:%lu: near eol: %s",
                    "dns_rdata_fromtext", name, line,
                    dns_result_totext(result));
            break;
        case isc_tokentype_eof:
            (*callback)(callbacks, "%s: %s:%lu: near eof: %s",
                    "dns_rdata_fromtext", name, line,
                    dns_result_totext(result));
            break;
        case isc_tokentype_number:
            (*callback)(callbacks, "%s: %s:%lu: near %lu: %s",
                    "dns_rdata_fromtext", name, line,
                    token->value.as_ulong,
                    dns_result_totext(result));
            break;
        case isc_tokentype_string:
        case isc_tokentype_qstring:
            (*callback)(callbacks, "%s: %s:%lu: near '%s': %s",
                    "dns_rdata_fromtext", name, line,
                    (char *)token->value.as_pointer,
                    dns_result_totext(result));
            break;
        default:
            (*callback)(callbacks, "%s: %s:%lu: %s",
                    "dns_rdata_fromtext", name, line,
                    dns_result_totext(result));
            break;
        }
    } else {
        (*callback)(callbacks, "dns_rdata_fromtext: %s:%lu: %s",
                name, line, dns_result_totext(result));
    }
}

dns_rdatatype_t
dns_rdata_covers(dns_rdata_t *rdata) {
    return (covers_sig(rdata));
}

isc_boolean_t
dns_rdatatype_ismeta(dns_rdatatype_t type) {
    if ((dns_rdatatype_attributes(type) & DNS_RDATATYPEATTR_META) != 0)
        return (ISC_TRUE);
    return (ISC_FALSE);
}

isc_boolean_t
dns_rdatatype_issingleton(dns_rdatatype_t type) {
    if ((dns_rdatatype_attributes(type) & DNS_RDATATYPEATTR_SINGLETON)
        != 0)
        return (ISC_TRUE);
    return (ISC_FALSE);
}

isc_boolean_t
dns_rdatatype_notquestion(dns_rdatatype_t type) {
    if ((dns_rdatatype_attributes(type) & DNS_RDATATYPEATTR_NOTQUESTION)
        != 0)
        return (ISC_TRUE);
    return (ISC_FALSE);
}

isc_boolean_t
dns_rdatatype_questiononly(dns_rdatatype_t type) {
    if ((dns_rdatatype_attributes(type) & DNS_RDATATYPEATTR_QUESTIONONLY)
        != 0)
        return (ISC_TRUE);
    return (ISC_FALSE);
}

isc_boolean_t
dns_rdataclass_ismeta(dns_rdataclass_t rdclass) {
    REQUIRE(rdclass < 65536);

    if (rdclass == dns_rdataclass_reserved0
        || rdclass == dns_rdataclass_none
        || rdclass == dns_rdataclass_any)
        return (ISC_TRUE);

    return (ISC_FALSE);  /* Assume it is not a meta class. */
}

isc_boolean_t
dns_rdatatype_isdnssec(dns_rdatatype_t type) {
    if ((dns_rdatatype_attributes(type) & DNS_RDATATYPEATTR_DNSSEC) != 0)
        return (ISC_TRUE);
    return (ISC_FALSE);
}

isc_boolean_t
dns_rdatatype_iszonecutauth(dns_rdatatype_t type) {
    if ((dns_rdatatype_attributes(type)
         & (DNS_RDATATYPEATTR_DNSSEC | DNS_RDATATYPEATTR_ZONECUTAUTH))
        != 0)
        return (ISC_TRUE);
    return (ISC_FALSE);
}

isc_boolean_t
dns_rdatatype_isknown(dns_rdatatype_t type) {
    if ((dns_rdatatype_attributes(type) & DNS_RDATATYPEATTR_UNKNOWN)
        == 0)
        return (ISC_TRUE);
    return (ISC_FALSE);
}