lib/dns/rdata.c

	rdata.c revision f8aae502686e2448c48f56697c212a50e2a1cbae
/*
 * Copyright (C) 1998, 1999 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 1.54 1999/07/09 12:48:51 gson Exp $ */

#include <config.h>

#include <stdarg.h>
#include <stdio.h>

#include <isc/base64.h>
#include <isc/buffer.h>
#include <isc/lex.h>
#include <isc/assertions.h>
#include <isc/error.h>
#include <isc/region.h>

#include <dns/types.h>
#include <dns/result.h>
#include <dns/rdata.h>
#include <dns/rdataclass.h>
#include <dns/rdatatype.h>
#include <dns/rcode.h>
#include <dns/cert.h>
#include <dns/secalg.h>
#include <dns/fixedname.h>
#include <dns/rdatastruct.h>
#include <dns/time.h>
#include <dns/ttl.h>

#define RETERR(x) do { \
    dns_result_t __r = (x); \
    if (__r != DNS_R_SUCCESS) \
        return (__r); \
    } while (0)

/*
 * 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. */
    char *linebreak;    /* Line break string. */
} dns_rdata_textctx_t;

static dns_result_t txt_totext(isc_region_t *source, isc_buffer_t *target);
static dns_result_t txt_fromtext(isc_textregion_t *source,
                     isc_buffer_t *target);
static dns_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 dns_result_t str_totext(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,
                      unsigned int type);
static dns_result_t uint32_tobuffer(isc_uint32_t,
                    isc_buffer_t *target);
static dns_result_t uint16_tobuffer(isc_uint32_t,
                    isc_buffer_t *target);
static dns_result_t uint8_tobuffer(isc_uint32_t value,
                       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 dns_result_t gettoken(isc_lex_t *lexer, isc_token_t *token,
                 isc_tokentype_t expect, isc_boolean_t eol);
static dns_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 dns_result_t btoa_totext(unsigned char *inbuf, int inbuflen,
                    isc_buffer_t *target);
static dns_result_t atob_tobuffer(isc_lex_t *lexer, isc_buffer_t *target);
static void     default_fromtext_callback(
                        dns_rdatacallbacks_t *callbacks,
                          char *, ...);

static void     fromtext_error(void (*callback)(dns_rdatacallbacks_t *,
                            char *, ...),
                       dns_rdatacallbacks_t *callbacks,
                       char *name, int line,
                       isc_token_t *token,
                       dns_result_t result);

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

static const char hexdigits[] = "0123456789abcdef";
static const char decdigits[] = "0123456789";
static const char octdigits[] = "01234567";

#include "code.h"

#define META 0x0001
#define RESERVED 0x0002

#define METATYPES \
    { 0, "NONE", META }, \
    { 31, "EID", RESERVED }, \
    { 32, "NIMLOC", RESERVED }, \
    { 34, "ATMA", RESERVED }, \
    { 100, "UINFO", RESERVED }, \
    { 101, "UID", RESERVED }, \
    { 102, "GID", RESERVED }, \
    { 249, "TKEY", META }, \
    { 250, "TSIG", META }, \
    { 251, "IXFR", META }, \
    { 252, "AXFR", META }, \
    { 253, "MAILB", META }, \
    { 254, "MAILA", META }, \
    { 255, "ANY", META },

#define METACLASSES \
    { 0, "NONE", META }, \
    { 255, "ANY", META },

#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}, \
    /* extended rcodes */ \
    { dns_rcode_badsig, "BADSIG", 0}, \
    { dns_rcode_badkey, "BADKEY", 0}, \
    { dns_rcode_badtime, "BADTIME", 0}, \
    { dns_rcode_badmode, "BADMODE", 0}, \
    { 0, NULL, 0 }

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

/* draft-ietf-dnssec-secext2-07.txt 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}


static struct tbl {
    unsigned int    value;
    char    *name;
    int flags;
} types[] = { TYPENAMES METATYPES {0, NULL, 0} },
classes[] = { CLASSNAMES METACLASSES { 0, NULL, 0} },
rcodes[] = { RCODENAMES },
certs[] = { CERTNAMES },
secalgs[] = { SECALGNAMES };

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

void
dns_rdata_init(dns_rdata_t *rdata) {

    REQUIRE(rdata != NULL);

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

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

int
dns_rdata_compare(dns_rdata_t *rdata1, 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);

    if (rdata1->class != rdata2->class)
        return (rdata1->class < rdata2->class ? -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 class,
             dns_rdatatype_t type, isc_region_t *r)
{

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

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

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

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

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

dns_result_t
dns_rdata_fromwire(dns_rdata_t *rdata, dns_rdataclass_t class,
           dns_rdatatype_t type, isc_buffer_t *source,
           dns_decompress_t *dctx, isc_boolean_t downcase,
           isc_buffer_t *target)
{
    dns_result_t result = DNS_R_NOTIMPLEMENTED;
    isc_region_t region;
    isc_buffer_t ss;
    isc_buffer_t st;
    isc_boolean_t use_default = ISC_FALSE;

    REQUIRE(isc_buffer_type(source) == ISC_BUFFERTYPE_BINARY);
    REQUIRE(isc_buffer_type(target) == ISC_BUFFERTYPE_BINARY);
    REQUIRE(dctx != NULL);

    ss = *source;
    st = *target;
    /* XXX */
    region.base = (unsigned char *)(target->base) + target->used;

    FROMWIRESWITCH

    if (use_default)
        (void)NULL;

    /* We should have consumed all out buffer */
    if (result == DNS_R_SUCCESS && !buffer_empty(source))
        result = DNS_R_EXTRADATA;

    if (rdata && result == DNS_R_SUCCESS) {
        region.length = target->used - st.used;
        dns_rdata_fromregion(rdata, class, type, &region);
    }

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

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

    REQUIRE(rdata != NULL);
    REQUIRE(isc_buffer_type(target) == ISC_BUFFERTYPE_BINARY);
    st = *target;

    TOWIRESWITCH

    if (use_default) {
        isc_buffer_available(target, &tr);
        if (tr.length < rdata->length)
            return (DNS_R_NOSPACE);
        memcpy(tr.base, rdata->data, rdata->length);
        isc_buffer_add(target, rdata->length);
        return (DNS_R_SUCCESS);
    }
    if (result != DNS_R_SUCCESS) {
        *target = st;
        dns_compress_rollback(cctx, target->used);
    }
    return (result);
}

dns_result_t
dns_rdata_fromtext(dns_rdata_t *rdata, dns_rdataclass_t class,
           dns_rdatatype_t type, isc_lex_t *lexer,
           dns_name_t *origin, isc_boolean_t downcase,
           isc_buffer_t *target, dns_rdatacallbacks_t *callbacks)
{
    dns_result_t result = DNS_R_NOTIMPLEMENTED;
    isc_region_t region;
    isc_buffer_t st;
    isc_boolean_t use_default = ISC_FALSE;
    isc_token_t token;
    unsigned int options = ISC_LEXOPT_EOL | ISC_LEXOPT_EOF |
                   ISC_LEXOPT_DNSMULTILINE | ISC_LEXOPT_ESCAPE;
    char *name;
    int line;
    void (*callback)(dns_rdatacallbacks_t *, char *, ...);
    isc_result_t iresult;

    if (origin != NULL)
        REQUIRE(dns_name_isabsolute(origin) == ISC_TRUE);
    REQUIRE(isc_buffer_type(target) == ISC_BUFFERTYPE_BINARY);

    st = *target;
    region.base = (unsigned char *)(target->base) + target->used;

    FROMTEXTSWITCH

    if (use_default)
        (void)NULL;

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

    if (callback == NULL)
        callback = default_fromtext_callback;
    /*
     * 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);
        iresult = isc_lex_gettoken(lexer, options, &token);
        if (iresult != ISC_R_SUCCESS) {
            if (result == DNS_R_SUCCESS) {
                switch (iresult) {
                case ISC_R_NOMEMORY:
                    result = DNS_R_NOMEMORY;
                    break;
                case ISC_R_NOSPACE:
                    result = DNS_R_NOSPACE;
                    break;
                default:
                    UNEXPECTED_ERROR(__FILE__, __LINE__,
                        "isc_lex_gettoken() failed: %s\n",
                        isc_result_totext(result));
                    result = DNS_R_UNEXPECTED;
                    break;
                }
            }
            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 == DNS_R_SUCCESS)
                result = DNS_R_EXTRATOKEN;
            if (callback != NULL) {
                fromtext_error(callback, callbacks, name,
                           line, &token, result);
                callback = NULL;
            }
        } else if (result != DNS_R_SUCCESS && callback != NULL) {
            fromtext_error(callback, callbacks, name, line,
                       &token, result);
            break;
        } else
            break;
    } while (1);

    if (rdata != NULL && result == DNS_R_SUCCESS) {
        region.length = target->used - st.used;
        dns_rdata_fromregion(rdata, class, type, &region);
    }
    if (result != DNS_R_SUCCESS) {
        *target = st;
    }
    return (result);
}

static dns_result_t
rdata_totext(dns_rdata_t *rdata, dns_rdata_textctx_t *tctx,
         isc_buffer_t *target)
{
    dns_result_t result = DNS_R_NOTIMPLEMENTED;
    isc_boolean_t use_default = ISC_FALSE;

    REQUIRE(rdata != NULL);
    REQUIRE(isc_buffer_type(target) == ISC_BUFFERTYPE_TEXT);
    if (tctx->origin != NULL)
        REQUIRE(dns_name_isabsolute(tctx->origin) == ISC_TRUE);

    /* Some DynDNS meta-RRs have empty rdata. */
    if (rdata->length == 0)
        return (DNS_R_SUCCESS);

    TOTEXTSWITCH

    if (use_default)
        (void)NULL;

    return (result);
}

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

dns_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)
{
    /* Set up formatting options for formatted output. */
    dns_rdata_textctx_t tctx;
    tctx.origin = origin;
    tctx.flags = flags;
    if ((flags & DNS_STYLEFLAG_MULTILINE) != 0) {
        tctx.width = width;
        tctx.linebreak = linebreak;
    } else {
        tctx.width = 60; /* Used for base64 word length only. */
        tctx.linebreak = " ";
    }
    return (rdata_totext(rdata, &tctx, target));
}

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

    REQUIRE(source != NULL);
    REQUIRE(isc_buffer_type(target) == ISC_BUFFERTYPE_BINARY);

    region.base = (unsigned char *)(target->base) + target->used;
    st = *target;

    FROMSTRUCTSWITCH

    if (use_default)
        (void)NULL;

    if (rdata != NULL && result == DNS_R_SUCCESS) {
        region.length = target->used - st.used;
        dns_rdata_fromregion(rdata, class, type, &region);
    }
    if (result != DNS_R_SUCCESS)
        *target = st;
    return (result);
}

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

    REQUIRE(rdata != NULL);

    TOSTRUCTSWITCH

    if (use_default)
        (void)NULL;

    return (result);
}

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

    FREESTRUCTSWITCH
}

dns_result_t
dns_rdataclass_fromtext(dns_rdataclass_t *classp, isc_textregion_t *source) {
    int i = 0;
    unsigned int n;

    while (classes[i].name != NULL) {
        n = strlen(classes[i].name);
        if (n == source->length &&
            strncasecmp(source->base, classes[i].name, n) == 0) {
            *classp = classes[i].value;
            if ((classes[i].flags & RESERVED) != 0)
                return (DNS_R_NOTIMPLEMENTED);
            return (DNS_R_SUCCESS);
        }
        i++;
    }
    return (DNS_R_UNKNOWN);
}

dns_result_t
dns_rdataclass_totext(dns_rdataclass_t class, isc_buffer_t *target) {
    int i = 0;
    char buf[sizeof "65000"];

    while (classes[i].name != NULL) {
        if (classes[i].value == class) {
            return (str_totext(classes[i].name, target));
        }
        i++;
    }
    sprintf(buf, "%u", class);
    return (str_totext(buf, target));
}

dns_result_t
dns_rdatatype_fromtext(dns_rdatatype_t *typep, isc_textregion_t *source) {
    int i = 0;
    unsigned int n;

    while (types[i].name != NULL) {
        n = strlen(types[i].name);
        if (n == source->length &&
            strncasecmp(source->base, types[i].name, n) == 0) {
            *typep = types[i].value;
            if ((types[i].flags & RESERVED) != 0)
                return (DNS_R_NOTIMPLEMENTED);
            return (DNS_R_SUCCESS);
        }
        i++;
    }
    return (DNS_R_UNKNOWN);
}

dns_result_t
dns_rdatatype_totext(dns_rdatatype_t type, isc_buffer_t *target) {
    int i = 0;
    char buf[sizeof "65000"];

    while (types[i].name != NULL) {
        if (types[i].value == type) {
            return (str_totext(types[i].name, target));
        }
        i++;
    }
    sprintf(buf, "%u", type);
    return (str_totext(buf, target));
}

dns_result_t
dns_rcode_fromtext(dns_rcode_t *rcodep, isc_textregion_t *source) {
    int i = 0;
    unsigned int n;

    while (rcodes[i].name != NULL) {
        n = strlen(rcodes[i].name);
        if (n == source->length &&
            strncasecmp(source->base, rcodes[i].name, n) == 0) {
            *rcodep = rcodes[i].value;
            return (DNS_R_SUCCESS);
        }
        i++;
    }
    return (DNS_R_UNKNOWN);
}

dns_result_t
dns_rcode_totext(dns_rcode_t rcode, isc_buffer_t *target) {
    int i = 0;
    char buf[sizeof "65000"];

    while (rcodes[i].name != NULL) {
        if (rcodes[i].value == rcode) {
            return (str_totext(rcodes[i].name, target));
        }
        i++;
    }
    sprintf(buf, "%u", rcode);
    return (str_totext(buf, target));
}

dns_result_t
dns_cert_fromtext(dns_cert_t *certp, isc_textregion_t *source) {
    int i = 0;
    unsigned int n;

    while (certs[i].name != NULL) {
        n = strlen(certs[i].name);
        if (n == source->length &&
            strncasecmp(source->base, certs[i].name, n) == 0) {
            *certp = certs[i].value;
            return (DNS_R_SUCCESS);
        }
        i++;
    }
    return (DNS_R_UNKNOWN);
}

dns_result_t
dns_cert_totext(dns_cert_t cert, isc_buffer_t *target) {
    int i = 0;
    char buf[sizeof "65000"];

    while (certs[i].name != NULL) {
        if (certs[i].value == cert) {
            return (str_totext(certs[i].name, target));
        }
        i++;
    }
    sprintf(buf, "%u", cert);
    return (str_totext(buf, target));
}

dns_result_t
dns_secalg_fromtext(dns_secalg_t *secalgp, isc_textregion_t *source) {
    int i = 0;
    unsigned int n;

    while (secalgs[i].name != NULL) {
        n = strlen(secalgs[i].name);
        if (n == source->length &&
            strncasecmp(source->base, secalgs[i].name, n) == 0) {
            *secalgp = secalgs[i].value;
            return (DNS_R_SUCCESS);
        }
        i++;
    }
    return (DNS_R_UNKNOWN);
}

dns_result_t
dns_secalg_totext(dns_secalg_t secalg, isc_buffer_t *target) {
    int i = 0;
    char buf[sizeof "65000"];

    while (secalgs[i].name != NULL) {
        if (secalgs[i].value == secalg) {
            return (str_totext(secalgs[i].name, target));
        }
        i++;
    }
    sprintf(buf, "%u", secalg);
    return (str_totext(buf, target));
}

 /* Private function */

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

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

    n = *sp++;

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

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

static dns_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_available(target, &tregion);
    s = source->base;
    n = source->length;
    t = tregion.base;
    nrem = tregion.length;
    escape = ISC_FALSE;
    if (nrem < 1)
        return (DNS_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(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 (DNS_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 (DNS_R_SUCCESS);
}

static dns_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_active(source, &sregion);
    if (sregion.length == 0)
        return(DNS_R_UNEXPECTEDEND);
    n = *sregion.base + 1;
    if (n > sregion.length)
        return (DNS_R_UNEXPECTEDEND);

    isc_buffer_available(target, &tregion);
    if (n > tregion.length)
        return (DNS_R_NOSPACE);

    memcpy(tregion.base, sregion.base, n);
    isc_buffer_forward(source, n);
    isc_buffer_add(target, n);
    return (DNS_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 dns_result_t
str_totext(char *source, isc_buffer_t *target) {
    unsigned int l;
    isc_region_t region;

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

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

    memcpy(region.base, source, l);
    isc_buffer_add(target, l);
    return (DNS_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,
          unsigned int type) {

    isc_buffer_init(buffer, region->base, region->length, type);
    isc_buffer_add(buffer, region->length);
    isc_buffer_setactive(buffer, region->length);
}

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

    isc_buffer_available(target, &region);
    if (region.length < 4)
        return (DNS_R_NOSPACE);
    isc_buffer_putuint32(target, value);
    return (DNS_R_SUCCESS);
}

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

    if (value > 0xffff)
        return (DNS_R_RANGE);
    isc_buffer_available(target, &region);
    if (region.length < 2)
        return (DNS_R_NOSPACE);
    isc_buffer_putuint16(target, value);
    return (DNS_R_SUCCESS);
}

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

    if (value > 0xff)
        return (DNS_R_RANGE);
    isc_buffer_available(target, &region);
    if (region.length < 1)
        return (DNS_R_NOSPACE);
    isc_buffer_putuint8(target, value);
    return (DNS_R_SUCCESS);
}

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 dns_result_t
gettoken(isc_lex_t *lexer, isc_token_t *token, isc_tokentype_t expect,
     isc_boolean_t eol)
{
    unsigned int options = ISC_LEXOPT_EOL | ISC_LEXOPT_EOF |
                   ISC_LEXOPT_DNSMULTILINE | ISC_LEXOPT_ESCAPE;
    isc_result_t result;

    if (expect == isc_tokentype_qstring)
        options |= ISC_LEXOPT_QSTRING;
    else if (expect == isc_tokentype_number)
        options |= ISC_LEXOPT_NUMBER;
    result = isc_lex_gettoken(lexer, options, token);
    switch (result) {
    case ISC_R_SUCCESS:
        break;
    case ISC_R_NOMEMORY:
        return (DNS_R_NOMEMORY);
    case ISC_R_NOSPACE:
        return (DNS_R_NOSPACE);
    default:
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "isc_lex_gettoken() failed: %s\n",
                 isc_result_totext(result));
                return (DNS_R_UNEXPECTED);
    }
    if (eol && ((token->type == isc_tokentype_eol) ||
            (token->type == isc_tokentype_eof)))
        return (DNS_R_SUCCESS);
    if (token->type == isc_tokentype_string &&
        expect == isc_tokentype_qstring)
        return (DNS_R_SUCCESS);
        if (token->type != expect) {
                isc_lex_ungettoken(lexer, token);
                if (token->type == isc_tokentype_eol ||
                    token->type == isc_tokentype_eof)
                        return (DNS_R_UNEXPECTEDEND);
                return (DNS_R_UNEXPECTEDTOKEN);
        }
    return (DNS_R_SUCCESS);
}

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

    isc_buffer_available(target, &tr);
        if (length > tr.length)
        return (DNS_R_NOSPACE);
    memcpy(tr.base, base, length);
    isc_buffer_add(target, length);
    return (DNS_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;
    if (!isascii(value&0xff))
        return (-1);
    if (isupper(value))
        value = tolower(value);
    if ((s = strchr(hexdigits, value)) == NULL)
        return (-1);
    return (s - hexdigits);
}

static int
decvalue(char value) {
    char *s;
    if (!isascii(value&0xff))
        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 dns_result_t byte_atob(int c, isc_buffer_t *target,
                  struct state *state);
static dns_result_t putbyte(int c, isc_buffer_t *, struct state *state);
static dns_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 dns_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(DNS_R_SUCCESS);
}

/* Compute checksum info and place c into target */
static dns_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_available(target, &tr);
    if (tr.length < 1)
        return (DNS_R_NOSPACE);
    tr.base[0] = c;
    isc_buffer_add(target, 1);
    return (DNS_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 dns_result_t
atob_tobuffer(isc_lex_t *lexer, isc_buffer_t *target) {
    isc_int32_t oeor, osum, orot;
    struct state statebuf, *state= &statebuf;
    isc_token_t token;
    char c;
    char *e;

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

    RETERR(gettoken(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(gettoken(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(gettoken(lexer, &token, isc_tokentype_string, ISC_FALSE));
    oeor = strtoul(token.value.as_pointer, &e, 16);
    if (*e != 0)
        return (DNS_R_SYNTAX);

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

    /* checksum */
    RETERR(gettoken(lexer, &token, isc_tokentype_string, ISC_FALSE));
    orot = strtoul(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(DNS_R_SUCCESS);
}

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

    isc_buffer_available(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 (DNS_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 (DNS_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 (DNS_R_SUCCESS);
}


/*
 * Encode the binary data from inbuf, of length inbuflen, into a
 * target.  Return success/failure status
 */
static dns_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, char *fmt, ...) {
    va_list ap;

    callbacks = callbacks; /*unused*/

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

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

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

isc_boolean_t
dns_rdatatype_ismeta(dns_rdatatype_t type) {
    struct tbl *t;
    REQUIRE(type < 65536);
    for (t = types; t->name != NULL; t++) {
        if (type == t->value)
            return ((t->flags & META) ? ISC_TRUE : ISC_FALSE);
    }
    return (ISC_FALSE); /* Unknown type, assume non-meta. */
}