lib/dns/masterdump.c

	masterdump.c revision dafcb997e390efa4423883dafd100c975c4095d6
/*
 * Copyright (C) 2004  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1999-2003  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 ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC 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: masterdump.c,v 1.73 2004/03/05 05:09:21 marka Exp $ */

#include <config.h>

#include <stdlib.h>

#include <isc/event.h>
#include <isc/file.h>
#include <isc/magic.h>
#include <isc/mem.h>
#include <isc/stdio.h>
#include <isc/string.h>
#include <isc/task.h>
#include <isc/util.h>

#include <dns/db.h>
#include <dns/dbiterator.h>
#include <dns/events.h>
#include <dns/fixedname.h>
#include <dns/log.h>
#include <dns/masterdump.h>
#include <dns/rdata.h>
#include <dns/rdataclass.h>
#include <dns/rdataset.h>
#include <dns/rdatasetiter.h>
#include <dns/rdatatype.h>
#include <dns/result.h>
#include <dns/time.h>
#include <dns/ttl.h>

#define DNS_DCTX_MAGIC      ISC_MAGIC('D', 'c', 't', 'x')
#define DNS_DCTX_VALID(d)   ISC_MAGIC_VALID(d, DNS_DCTX_MAGIC)

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

struct dns_master_style {
    unsigned int flags;     /* DNS_STYLEFLAG_* */
    unsigned int ttl_column;
    unsigned int class_column;
    unsigned int type_column;
    unsigned int rdata_column;
    unsigned int line_length;
    unsigned int tab_width;
};

/*
 * The maximum length of the newline+indentation that is output
 * when inserting a line break in an RR.  This effectively puts an
 * upper limits on the value of "rdata_column", because if it is
 * very large, the tabs and spaces needed to reach it will not fit.
 */
#define DNS_TOTEXT_LINEBREAK_MAXLEN 100

/*
 * Context structure for a masterfile dump in progress.
 */
typedef struct dns_totext_ctx {
    dns_master_style_t  style;
    isc_boolean_t       class_printed;
    char *          linebreak;
    char            linebreak_buf[DNS_TOTEXT_LINEBREAK_MAXLEN];
    dns_name_t *        origin;
    dns_name_t *        neworigin;
    dns_fixedname_t     origin_fixname;
    isc_uint32_t        current_ttl;
    isc_boolean_t       current_ttl_valid;
} dns_totext_ctx_t;

LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_default = {
    DNS_STYLEFLAG_OMIT_OWNER |
    DNS_STYLEFLAG_OMIT_CLASS |
    DNS_STYLEFLAG_REL_OWNER |
    DNS_STYLEFLAG_REL_DATA |
    DNS_STYLEFLAG_OMIT_TTL |
    DNS_STYLEFLAG_TTL |
    DNS_STYLEFLAG_COMMENT |
    DNS_STYLEFLAG_MULTILINE,
    24, 24, 24, 32, 80, 8
};

LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_full = {
    DNS_STYLEFLAG_COMMENT,
    46, 46, 46, 64, 120, 8
};

LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_explicitttl = {
    DNS_STYLEFLAG_OMIT_OWNER |
    DNS_STYLEFLAG_OMIT_CLASS |
    DNS_STYLEFLAG_REL_OWNER |
    DNS_STYLEFLAG_REL_DATA |
    DNS_STYLEFLAG_COMMENT |
    DNS_STYLEFLAG_MULTILINE,
    24, 32, 32, 40, 80, 8
};

LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_cache = {
    DNS_STYLEFLAG_OMIT_OWNER |
    DNS_STYLEFLAG_OMIT_CLASS |
    DNS_STYLEFLAG_MULTILINE |
    DNS_STYLEFLAG_TRUST |
    DNS_STYLEFLAG_NCACHE,
    24, 32, 32, 40, 80, 8
};

LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_simple = {
    0,
    24, 32, 32, 40, 80, 8
};

/*
 * A style suitable for dns_rdataset_totext().
 */
LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_debug = {
    DNS_STYLEFLAG_REL_OWNER,
    24, 32, 40, 48, 80, 8
};


#define N_SPACES 10
static char spaces[N_SPACES+1] = "          ";

#define N_TABS 10
static char tabs[N_TABS+1] = "\t\t\t\t\t\t\t\t\t\t";

struct dns_dumpctx {
    unsigned int        magic;
    isc_mem_t       *mctx;
    isc_mutex_t     lock;
    unsigned int        references;
    isc_boolean_t       canceled;
    isc_boolean_t       first;
    isc_boolean_t       do_date;
    isc_stdtime_t       now;
    FILE            *f;
    dns_db_t        *db;
    dns_dbversion_t     *version;
    dns_dbiterator_t    *dbiter;
    dns_totext_ctx_t    tctx;
    isc_task_t      *task;
    dns_dumpdonefunc_t  done;
    void            *done_arg;
    unsigned int        nodes;
    /* dns_master_dumpinc() */
    char            *file;
    char            *tmpfile;
};

#define NXDOMAIN(x) (((x)->attributes & DNS_RDATASETATTR_NXDOMAIN) != 0)

/*
 * Output tabs and spaces to go from column '*current' to
 * column 'to', and update '*current' to reflect the new
 * current column.
 */
static isc_result_t
indent(unsigned int *current, unsigned int to, int tabwidth,
       isc_buffer_t *target)
{
    isc_region_t r;
    unsigned char *p;
    unsigned int from;
    int ntabs, nspaces, t;

    from = *current;

    if (to < from + 1)
        to = from + 1;

    ntabs = to / tabwidth - from / tabwidth;
    if (ntabs < 0)
        ntabs = 0;

    if (ntabs > 0) {
        isc_buffer_availableregion(target, &r);
        if (r.length < (unsigned) ntabs)
            return (ISC_R_NOSPACE);
        p = r.base;

        t = ntabs;
        while (t) {
            int n = t;
            if (n > N_TABS)
                n = N_TABS;
            memcpy(p, tabs, n);
            p += n;
            t -= n;
        }
        isc_buffer_add(target, ntabs);
        from = (to / tabwidth) * tabwidth;
    }

    nspaces = to - from;
    INSIST(nspaces >= 0);

    isc_buffer_availableregion(target, &r);
    if (r.length < (unsigned) nspaces)
        return (ISC_R_NOSPACE);
    p = r.base;

    t = nspaces;
    while (t) {
        int n = t;
        if (n > N_SPACES)
            n = N_SPACES;
        memcpy(p, spaces, n);
        p += n;
        t -= n;
    }
    isc_buffer_add(target, nspaces);

    *current = to;
    return (ISC_R_SUCCESS);
}

static isc_result_t
totext_ctx_init(const dns_master_style_t *style, dns_totext_ctx_t *ctx) {
    isc_result_t result;

    REQUIRE(style->tab_width != 0);

    ctx->style = *style;
    ctx->class_printed = ISC_FALSE;

    dns_fixedname_init(&ctx->origin_fixname);

    /*
     * Set up the line break string if needed.
     */
    if ((ctx->style.flags & DNS_STYLEFLAG_MULTILINE) != 0) {
        isc_buffer_t buf;
        isc_region_t r;
        unsigned int col = 0;

        isc_buffer_init(&buf, ctx->linebreak_buf,
                sizeof(ctx->linebreak_buf));

        isc_buffer_availableregion(&buf, &r);
        if (r.length < 1)
            return (DNS_R_TEXTTOOLONG);
        r.base[0] = '\n';
        isc_buffer_add(&buf, 1);

        result = indent(&col, ctx->style.rdata_column,
                ctx->style.tab_width, &buf);
        /*
         * Do not return ISC_R_NOSPACE if the line break string
         * buffer is too small, because that would just make
         * dump_rdataset() retry indenfinitely with ever
         * bigger target buffers.  That's a different buffer,
         * so it won't help.  Use DNS_R_TEXTTOOLONG as a substitute.
         */
        if (result == ISC_R_NOSPACE)
            return (DNS_R_TEXTTOOLONG);
        if (result != ISC_R_SUCCESS)
            return (result);

        isc_buffer_availableregion(&buf, &r);
        if (r.length < 1)
            return (DNS_R_TEXTTOOLONG);
        r.base[0] = '\0';
        isc_buffer_add(&buf, 1);
        ctx->linebreak = ctx->linebreak_buf;
    } else {
        ctx->linebreak = NULL;
    }

    ctx->origin = NULL;
    ctx->neworigin = NULL;
    ctx->current_ttl = 0;
    ctx->current_ttl_valid = ISC_FALSE;

    return (ISC_R_SUCCESS);
}

#define INDENT_TO(col) \
    do { \
         if ((result = indent(&column, ctx->style.col, \
                      ctx->style.tab_width, target)) \
             != ISC_R_SUCCESS) \
                return (result); \
    } while (0)


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);
}

/*
 * Convert 'rdataset' to master file text format according to 'ctx',
 * storing the result in 'target'.  If 'owner_name' is NULL, it
 * is omitted; otherwise 'owner_name' must be valid and have at least
 * one label.
 */

static isc_result_t
rdataset_totext(dns_rdataset_t *rdataset,
        dns_name_t *owner_name,
        dns_totext_ctx_t *ctx,
        isc_boolean_t omit_final_dot,
        isc_buffer_t *target)
{
    isc_result_t result;
    unsigned int column;
    isc_boolean_t first = ISC_TRUE;
    isc_uint32_t current_ttl;
    isc_boolean_t current_ttl_valid;
    dns_rdatatype_t type;

    REQUIRE(DNS_RDATASET_VALID(rdataset));

    result = dns_rdataset_first(rdataset);
    REQUIRE(result == ISC_R_SUCCESS);

    current_ttl = ctx->current_ttl;
    current_ttl_valid = ctx->current_ttl_valid;

    do {
        column = 0;

        /*
         * Owner name.
         */
        if (owner_name != NULL &&
            ! ((ctx->style.flags & DNS_STYLEFLAG_OMIT_OWNER) != 0 &&
               !first))
        {
            unsigned int name_start = target->used;
            RETERR(dns_name_totext(owner_name,
                           omit_final_dot,
                           target));
            column += target->used - name_start;
        }

        /*
         * TTL.
         */
        if ((ctx->style.flags & DNS_STYLEFLAG_NO_TTL) == 0 &&
            !((ctx->style.flags & DNS_STYLEFLAG_OMIT_TTL) != 0 &&
              current_ttl_valid &&
              rdataset->ttl == current_ttl))
        {
            char ttlbuf[64];
            isc_region_t r;
            unsigned int length;

            INDENT_TO(ttl_column);
            length = snprintf(ttlbuf, sizeof(ttlbuf), "%u",
                      rdataset->ttl);
            INSIST(length <= sizeof(ttlbuf));
            isc_buffer_availableregion(target, &r);
            if (r.length < length)
                return (ISC_R_NOSPACE);
            memcpy(r.base, ttlbuf, length);
            isc_buffer_add(target, length);
            column += length;

            /*
             * If the $TTL directive is not in use, the TTL we
             * just printed becomes the default for subsequent RRs.
             */
            if ((ctx->style.flags & DNS_STYLEFLAG_TTL) == 0) {
                current_ttl = rdataset->ttl;
                current_ttl_valid = ISC_TRUE;
            }
        }

        /*
         * Class.
         */
        if ((ctx->style.flags & DNS_STYLEFLAG_NO_CLASS) == 0 &&
            ((ctx->style.flags & DNS_STYLEFLAG_OMIT_CLASS) == 0 ||
             ctx->class_printed == ISC_FALSE))
        {
            unsigned int class_start;
            INDENT_TO(class_column);
            class_start = target->used;
            result = dns_rdataclass_totext(rdataset->rdclass,
                               target);
            if (result != ISC_R_SUCCESS)
                return (result);
            column += (target->used - class_start);
        }

        /*
         * Type.
         */

        if (rdataset->type == 0) {
            type = rdataset->covers;
        } else {
            type = rdataset->type;
        }

        {
            unsigned int type_start;
            INDENT_TO(type_column);
            type_start = target->used;
            if (rdataset->type == 0)
                RETERR(str_totext("\\-", target));
            result = dns_rdatatype_totext(type, target);
            if (result != ISC_R_SUCCESS)
                return (result);
            column += (target->used - type_start);
        }

        /*
         * Rdata.
         */
        INDENT_TO(rdata_column);
        if (rdataset->type == 0) {
            if (NXDOMAIN(rdataset))
                RETERR(str_totext(";-$NXDOMAIN\n", target));
            else
                RETERR(str_totext(";-$NXRRSET\n", target));
        } else {
            dns_rdata_t rdata = DNS_RDATA_INIT;
            isc_region_t r;

            dns_rdataset_current(rdataset, &rdata);

            RETERR(dns_rdata_tofmttext(&rdata,
                           ctx->origin,
                           ctx->style.flags,
                           ctx->style.line_length -
                               ctx->style.rdata_column,
                           ctx->linebreak,
                           target));

            isc_buffer_availableregion(target, &r);
            if (r.length < 1)
                return (ISC_R_NOSPACE);
            r.base[0] = '\n';
            isc_buffer_add(target, 1);
        }

        first = ISC_FALSE;
        result = dns_rdataset_next(rdataset);
    } while (result == ISC_R_SUCCESS);

    if (result != ISC_R_NOMORE)
        return (result);

    /*
     * Update the ctx state to reflect what we just printed.
     * This is done last, only when we are sure we will return
     * success, because this function may be called multiple
     * times with increasing buffer sizes until it succeeds,
     * and failed attempts must not update the state prematurely.
     */
    ctx->class_printed = ISC_TRUE;
    ctx->current_ttl= current_ttl;
    ctx->current_ttl_valid = current_ttl_valid;

    return (ISC_R_SUCCESS);
}

/*
 * Print the name, type, and class of an empty rdataset,
 * such as those used to represent the question section
 * of a DNS message.
 */
static isc_result_t
question_totext(dns_rdataset_t *rdataset,
        dns_name_t *owner_name,
        dns_totext_ctx_t *ctx,
        isc_boolean_t omit_final_dot,
        isc_buffer_t *target)
{
    unsigned int column;
    isc_result_t result;
    isc_region_t r;

    REQUIRE(DNS_RDATASET_VALID(rdataset));
    result = dns_rdataset_first(rdataset);
    REQUIRE(result == ISC_R_NOMORE);

    column = 0;

    /* Owner name */
    {
        unsigned int name_start = target->used;
        RETERR(dns_name_totext(owner_name,
                       omit_final_dot,
                       target));
        column += target->used - name_start;
    }

    /* Class */
    {
        unsigned int class_start;
        INDENT_TO(class_column);
        class_start = target->used;
        result = dns_rdataclass_totext(rdataset->rdclass, target);
        if (result != ISC_R_SUCCESS)
            return (result);
        column += (target->used - class_start);
    }

    /* Type */
    {
        unsigned int type_start;
        INDENT_TO(type_column);
        type_start = target->used;
        result = dns_rdatatype_totext(rdataset->type, target);
        if (result != ISC_R_SUCCESS)
            return (result);
        column += (target->used - type_start);
    }

    isc_buffer_availableregion(target, &r);
    if (r.length < 1)
        return (ISC_R_NOSPACE);
    r.base[0] = '\n';
    isc_buffer_add(target, 1);

    return (ISC_R_SUCCESS);
}

isc_result_t
dns_rdataset_totext(dns_rdataset_t *rdataset,
            dns_name_t *owner_name,
            isc_boolean_t omit_final_dot,
            isc_boolean_t question,
            isc_buffer_t *target)
{
    dns_totext_ctx_t ctx;
    isc_result_t result;
    result = totext_ctx_init(&dns_master_style_debug, &ctx);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "could not set master file style");
        return (ISC_R_UNEXPECTED);
    }

    /*
     * The caller might want to give us an empty owner
     * name (e.g. if they are outputting into a master
     * file and this rdataset has the same name as the
     * previous one.)
     */
    if (dns_name_countlabels(owner_name) == 0)
        owner_name = NULL;

    if (question)
        return (question_totext(rdataset, owner_name, &ctx,
                    omit_final_dot, target));
    else
        return (rdataset_totext(rdataset, owner_name, &ctx,
                    omit_final_dot, target));
}

isc_result_t
dns_master_rdatasettotext(dns_name_t *owner_name,
              dns_rdataset_t *rdataset,
              const dns_master_style_t *style,
              isc_buffer_t *target)
{
    dns_totext_ctx_t ctx;
    isc_result_t result;
    result = totext_ctx_init(style, &ctx);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "could not set master file style");
        return (ISC_R_UNEXPECTED);
    }

    return (rdataset_totext(rdataset, owner_name, &ctx,
                ISC_FALSE, target));
}

isc_result_t
dns_master_questiontotext(dns_name_t *owner_name,
              dns_rdataset_t *rdataset,
              const dns_master_style_t *style,
              isc_buffer_t *target)
{
    dns_totext_ctx_t ctx;
    isc_result_t result;
    result = totext_ctx_init(style, &ctx);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "could not set master file style");
        return (ISC_R_UNEXPECTED);
    }

    return (question_totext(rdataset, owner_name, &ctx,
                ISC_FALSE, target));
}

/*
 * Print an rdataset.  'buffer' is a scratch buffer, which must have been
 * dynamically allocated by the caller.  It must be large enough to
 * hold the result from dns_ttl_totext().  If more than that is needed,
 * the buffer will be grown automatically.
 */

static isc_result_t
dump_rdataset(isc_mem_t *mctx, dns_name_t *name, dns_rdataset_t *rdataset,
          dns_totext_ctx_t *ctx,
          isc_buffer_t *buffer, FILE *f)
{
    isc_region_t r;
    isc_result_t result;

    REQUIRE(buffer->length > 0);

    /*
     * Output a $TTL directive if needed.
     */

    if ((ctx->style.flags & DNS_STYLEFLAG_TTL) != 0) {
        if (ctx->current_ttl_valid == ISC_FALSE ||
            ctx->current_ttl != rdataset->ttl)
        {
            if ((ctx->style.flags & DNS_STYLEFLAG_COMMENT) != 0)
            {
                isc_buffer_clear(buffer);
                result = dns_ttl_totext(rdataset->ttl,
                            ISC_TRUE, buffer);
                INSIST(result == ISC_R_SUCCESS);
                isc_buffer_usedregion(buffer, &r);
                fprintf(f, "$TTL %u\t; %.*s\n", rdataset->ttl,
                    (int) r.length, (char *) r.base);
            } else {
                fprintf(f, "$TTL %u\n", rdataset->ttl);
            }
            ctx->current_ttl = rdataset->ttl;
            ctx->current_ttl_valid = ISC_TRUE;
        }
    }

    isc_buffer_clear(buffer);

    /*
     * Generate the text representation of the rdataset into
     * the buffer.  If the buffer is too small, grow it.
     */
    for (;;) {
        int newlength;
        void *newmem;
        result = rdataset_totext(rdataset, name, ctx,
                     ISC_FALSE, buffer);
        if (result != ISC_R_NOSPACE)
            break;

        newlength = buffer->length * 2;
        newmem = isc_mem_get(mctx, newlength);
        if (newmem == NULL)
            return (ISC_R_NOMEMORY);
        isc_mem_put(mctx, buffer->base, buffer->length);
        isc_buffer_init(buffer, newmem, newlength);
    }
    if (result != ISC_R_SUCCESS)
        return (result);

    /*
     * Write the buffer contents to the master file.
     */
    isc_buffer_usedregion(buffer, &r);
    result = isc_stdio_write(r.base, 1, (size_t)r.length, f, NULL);

    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "master file write failed: %s",
                 isc_result_totext(result));
        return (result);
    }

    return (ISC_R_SUCCESS);
}

/*
 * Define the order in which rdatasets should be printed in zone
 * files.  We will print SOA and NS records before others, SIGs
 * immediately following the things they sign, and order everything
 * else by RR number.  This is all just for aesthetics and
 * compatibility with buggy software that expects the SOA to be first;
 * the DNS specifications allow any order.
 */

static int
dump_order(const dns_rdataset_t *rds) {
    int t;
    int sig;
    if (rds->type == dns_rdatatype_rrsig) {
        t = rds->covers;
        sig = 1;
    } else {
        t = rds->type;
        sig = 0;
    }
    switch (t) {
    case dns_rdatatype_soa:
        t = 0;
        break;
    case dns_rdatatype_ns:
        t = 1;
        break;
    default:
        t += 2;
        break;
    }
    return (t << 1) + sig;
}

static int
dump_order_compare(const void *a, const void *b) {
    return (dump_order(*((const dns_rdataset_t * const *) a)) -
        dump_order(*((const dns_rdataset_t * const *) b)));
}

/*
 * Dump all the rdatasets of a domain name to a master file.  We make
 * a "best effort" attempt to sort the RRsets in a nice order, but if
 * there are more than MAXSORT RRsets, we punt and only sort them in
 * groups of MAXSORT.  This is not expected to ever happen in practice
 * since much less than 64 RR types have been registered with the
 * IANA, so far, and the output will be correct (though not
 * aesthetically pleasing) even if it does happen.
 */

#define MAXSORT 64

static const char *trustnames[] = {
    "none",
    "pending",
    "additional",
    "glue",
    "answer",
    "authauthority",
    "authanswer",
    "secure",
    "local" /* aka ultimate */
};

static isc_result_t
dump_rdatasets(isc_mem_t *mctx, dns_name_t *name, dns_rdatasetiter_t *rdsiter,
           dns_totext_ctx_t *ctx,
           isc_buffer_t *buffer, FILE *f)
{
    isc_result_t itresult, dumpresult;
    isc_region_t r;
    dns_rdataset_t rdatasets[MAXSORT];
    dns_rdataset_t *sorted[MAXSORT];
    int i, n;

    itresult = dns_rdatasetiter_first(rdsiter);
    dumpresult = ISC_R_SUCCESS;

    if (itresult == ISC_R_SUCCESS && ctx->neworigin != NULL) {
        isc_buffer_clear(buffer);
        itresult = dns_name_totext(ctx->neworigin, ISC_FALSE, buffer);
        RUNTIME_CHECK(itresult == ISC_R_SUCCESS);
        isc_buffer_usedregion(buffer, &r);
        fprintf(f, "$ORIGIN %.*s\n", (int) r.length, (char *) r.base);
        ctx->neworigin = NULL;
    }

 again:
    for (i = 0;
         itresult == ISC_R_SUCCESS && i < MAXSORT;
         itresult = dns_rdatasetiter_next(rdsiter), i++) {
        dns_rdataset_init(&rdatasets[i]);
        dns_rdatasetiter_current(rdsiter, &rdatasets[i]);
        sorted[i] = &rdatasets[i];
    }
    n = i;
    INSIST(n <= MAXSORT);

    qsort(sorted, n, sizeof(sorted[0]), dump_order_compare);

    for (i = 0; i < n; i++) {
        dns_rdataset_t *rds = sorted[i];
        if (ctx->style.flags & DNS_STYLEFLAG_TRUST) {
            unsigned int trust = rds->trust;
            INSIST(trust < (sizeof(trustnames) /
                    sizeof(trustnames[0])));
            fprintf(f, "; %s\n", trustnames[trust]);
        }
        if (rds->type == 0 &&
            (ctx->style.flags & DNS_STYLEFLAG_NCACHE) == 0) {
            /* Omit negative cache entries */
        } else {
            isc_result_t result =
                dump_rdataset(mctx, name, rds, ctx,
                           buffer, f);
            if (result != ISC_R_SUCCESS)
                dumpresult = result;
            if ((ctx->style.flags & DNS_STYLEFLAG_OMIT_OWNER) != 0)
                name = NULL;
        }
        dns_rdataset_disassociate(rds);
    }

    if (dumpresult != ISC_R_SUCCESS)
        return (dumpresult);

    /*
     * If we got more data than could be sorted at once,
     * go handle the rest.
     */
    if (itresult == ISC_R_SUCCESS)
        goto again;

    if (itresult == ISC_R_NOMORE)
        itresult = ISC_R_SUCCESS;

    return (itresult);
}


/*
 * Initial size of text conversion buffer.  The buffer is used
 * for several purposes: converting origin names, rdatasets,
 * $DATE timestamps, and comment strings for $TTL directives.
 *
 * When converting rdatasets, it is dynamically resized, but
 * when converting origins, timestamps, etc it is not.  Therefore,
 * the  initial size must large enough to hold the longest possible
 * text representation of any domain name (for $ORIGIN).
 */
static const int initial_buffer_length = 1200;

static isc_result_t
dumptostreaminc(dns_dumpctx_t *dctx);

static void
dumpctx_destroy(dns_dumpctx_t *dctx) {

    dctx->magic = 0;
    DESTROYLOCK(&dctx->lock);
    if (dctx->version != NULL)
        dns_db_closeversion(dctx->db, &dctx->version, ISC_FALSE);
    dns_dbiterator_destroy(&dctx->dbiter);
    dns_db_detach(&dctx->db);
    if (dctx->task != NULL)
        isc_task_detach(&dctx->task);
    if (dctx->file != NULL)
        isc_mem_free(dctx->mctx, dctx->file);
    if (dctx->tmpfile != NULL)
        isc_mem_free(dctx->mctx, dctx->tmpfile);
    isc_mem_putanddetach(&dctx->mctx, dctx, sizeof(*dctx));
}

void
dns_dumpctx_attach(dns_dumpctx_t *source, dns_dumpctx_t **target) {

    REQUIRE(DNS_DCTX_VALID(source));
    REQUIRE(target != NULL && *target == NULL);

    LOCK(&source->lock);
    INSIST(source->references > 0);
    source->references++;
    INSIST(source->references != 0);    /* Overflow? */
    UNLOCK(&source->lock);

    *target = source;
}

void
dns_dumpctx_detach(dns_dumpctx_t **dctxp) {
    dns_dumpctx_t *dctx;
    isc_boolean_t need_destroy = ISC_FALSE;

    REQUIRE(dctxp != NULL);
    dctx = *dctxp;
    REQUIRE(DNS_DCTX_VALID(dctx));

    *dctxp = NULL;

    LOCK(&dctx->lock);
    INSIST(dctx->references != 0);
    dctx->references--;
    if (dctx->references == 0)
        need_destroy = ISC_TRUE;
    UNLOCK(&dctx->lock);
    if (need_destroy)
        dumpctx_destroy(dctx);
}

dns_dbversion_t *
dns_dumpctx_version(dns_dumpctx_t *dctx) {
        REQUIRE(DNS_DCTX_VALID(dctx));
    return (dctx->version);
}

dns_db_t *
dns_dumpctx_db(dns_dumpctx_t *dctx) {
        REQUIRE(DNS_DCTX_VALID(dctx));
    return (dctx->db);
}

void
dns_dumpctx_cancel(dns_dumpctx_t *dctx) {
    REQUIRE(DNS_DCTX_VALID(dctx));

    LOCK(&dctx->lock);
    dctx->canceled = ISC_TRUE;
    UNLOCK(&dctx->lock);
}

static isc_result_t
closeandrename(FILE *f, isc_result_t result, const char *temp, const char *file)
{
    isc_result_t tresult;
    isc_boolean_t logit = ISC_TF(result == ISC_R_SUCCESS);

    if (result == ISC_R_SUCCESS)
        result = isc_stdio_sync(f);
    if (result != ISC_R_SUCCESS && logit) {
        isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                  DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                  "dumping master file: %s: fsync: %s",
                  temp, isc_result_totext(result));
        logit = ISC_FALSE;
    }
    tresult = isc_stdio_close(f);
    if (result == ISC_R_SUCCESS)
        result = tresult;
    if (result != ISC_R_SUCCESS && logit) {
        isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                  DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                  "dumping master file: %s: fclose: %s",
                  temp, isc_result_totext(result));
        logit = ISC_FALSE;
    }
    if (result == ISC_R_SUCCESS)
        result = isc_file_rename(temp, file);
    else
        (void)isc_file_remove(temp);
    if (result != ISC_R_SUCCESS && logit) {
        isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                  DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                  "dumping master file: rename: %s: %s",
                  file, isc_result_totext(result));
    }
    return (result);
}

static void
dump_quantum(isc_task_t *task, isc_event_t *event) {
    isc_result_t result;
    dns_dumpctx_t *dctx;

    REQUIRE(event != NULL);
    dctx = event->ev_arg;
    REQUIRE(DNS_DCTX_VALID(dctx));
    if (dctx->canceled)
        result = ISC_R_CANCELED;
    else
        result = dumptostreaminc(dctx);
    if (result == DNS_R_CONTINUE) {
        event->ev_arg = dctx;
        isc_task_send(task, &event);
        return;
    }

    if (dctx->file != NULL)
        result = closeandrename(dctx->f, result,
                    dctx->tmpfile, dctx->file);
    if (dctx->version != NULL)
        dns_db_closeversion(dctx->db, &dctx->version, ISC_FALSE);
    (dctx->done)(dctx->done_arg, result);
    isc_event_free(&event);
    dns_dumpctx_detach(&dctx);
}

static isc_result_t
task_send(dns_dumpctx_t *dctx) {
    isc_event_t *event;

    event = isc_event_allocate(dctx->mctx, NULL, DNS_EVENT_DUMPQUANTUM,
                   dump_quantum, dctx, sizeof(*event));
    if (event == NULL)
        return (ISC_R_NOMEMORY);
    isc_task_send(dctx->task, &event);
    return (ISC_R_SUCCESS);
}

static isc_result_t
dumpctx_create(isc_mem_t *mctx, dns_db_t *db, dns_dbversion_t *version,
           const dns_master_style_t *style, FILE *f, dns_dumpctx_t **dctxp)
{
    dns_dumpctx_t *dctx;
    isc_result_t result;
    isc_boolean_t relative;

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

    dctx->mctx = NULL;
    dctx->f = f;
    dctx->dbiter = NULL;
    dctx->db = NULL;
    dctx->version = NULL;
    dctx->done = NULL;
    dctx->done_arg = NULL;
    dctx->task = NULL;
    dctx->nodes = 0;
    dctx->first = ISC_TRUE;
    dctx->canceled = ISC_FALSE;
    dctx->file = NULL;
    dctx->tmpfile = NULL;

    result = totext_ctx_init(style, &dctx->tctx);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "could not set master file style");
        goto cleanup;
    }

    isc_stdtime_get(&dctx->now);
    dns_db_attach(db, &dctx->db);

    dctx->do_date = dns_db_iscache(dctx->db);

    relative = ((dctx->tctx.style.flags & DNS_STYLEFLAG_REL_OWNER) != 0) ?
            ISC_TRUE : ISC_FALSE;
    result = dns_db_createiterator(dctx->db, relative, &dctx->dbiter);
    if (result != ISC_R_SUCCESS)
        goto cleanup;

    result = isc_mutex_init(&dctx->lock);
    if (result != ISC_R_SUCCESS)
        goto cleanup;
    if (version != NULL)
        dns_db_attachversion(dctx->db, version, &dctx->version);
    else if (!dns_db_iscache(db))
        dns_db_currentversion(dctx->db, &dctx->version);
    isc_mem_attach(mctx, &dctx->mctx);
    dctx->references = 1;
    dctx->magic = DNS_DCTX_MAGIC;
    *dctxp = dctx;
    return (ISC_R_SUCCESS);

 cleanup:
    if (dctx->dbiter != NULL)
        dns_dbiterator_destroy(&dctx->dbiter);
    if (dctx->db != NULL)
        dns_db_detach(&dctx->db);
    if (dctx != NULL)
        isc_mem_put(mctx, dctx, sizeof(*dctx));
    return (result);
}

static isc_result_t
dumptostreaminc(dns_dumpctx_t *dctx) {
    isc_result_t result;
    isc_buffer_t buffer;
    char *bufmem;
    isc_region_t r;
    dns_name_t *name;
    dns_fixedname_t fixname;
    unsigned int nodes;

    bufmem = isc_mem_get(dctx->mctx, initial_buffer_length);
    if (bufmem == NULL)
        return (ISC_R_NOMEMORY);

    isc_buffer_init(&buffer, bufmem, initial_buffer_length);

    dns_fixedname_init(&fixname);
    name = dns_fixedname_name(&fixname);

    if (dctx->first) {
        /*
         * If the database has cache semantics, output an RFC2540
         * $DATE directive so that the TTLs can be adjusted when
         * it is reloaded.  For zones it is not really needed, and
         * it would make the file incompatible with pre-RFC2540
         * software, so we omit it in the zone case.
         */
        if (dctx->do_date) {
            result = dns_time32_totext(dctx->now, &buffer);
            RUNTIME_CHECK(result == ISC_R_SUCCESS);
            isc_buffer_usedregion(&buffer, &r);
            fprintf(dctx->f, "$DATE %.*s\n",
                (int) r.length, (char *) r.base);
        }
        result = dns_dbiterator_first(dctx->dbiter);
        dctx->first = ISC_FALSE;
    } else
        result = ISC_R_SUCCESS;

    nodes = dctx->nodes;
    while (result == ISC_R_SUCCESS && (dctx->nodes == 0 || nodes--)) {
        dns_rdatasetiter_t *rdsiter = NULL;
        dns_dbnode_t *node = NULL;

        result = dns_dbiterator_current(dctx->dbiter, &node, name);
        if (result != ISC_R_SUCCESS && result != DNS_R_NEWORIGIN)
            break;
        if (result == DNS_R_NEWORIGIN) {
            dns_name_t *origin =
                dns_fixedname_name(&dctx->tctx.origin_fixname);
            result = dns_dbiterator_origin(dctx->dbiter, origin);
            RUNTIME_CHECK(result == ISC_R_SUCCESS);
            if ((dctx->tctx.style.flags & DNS_STYLEFLAG_REL_DATA) != 0)
                dctx->tctx.origin = origin;
            dctx->tctx.neworigin = origin;
        }
        result = dns_db_allrdatasets(dctx->db, node, dctx->version,
                         dctx->now, &rdsiter);
        if (result != ISC_R_SUCCESS) {
            dns_db_detachnode(dctx->db, &node);
            goto fail;
        }
        result = dump_rdatasets(dctx->mctx, name, rdsiter, &dctx->tctx,
                    &buffer, dctx->f);
        dns_rdatasetiter_destroy(&rdsiter);
        if (result != ISC_R_SUCCESS) {
            dns_db_detachnode(dctx->db, &node);
            goto fail;
        }
        dns_db_detachnode(dctx->db, &node);
        result = dns_dbiterator_next(dctx->dbiter);
    }

    if (dctx->nodes != 0 && result == ISC_R_SUCCESS) {
        dns_dbiterator_pause(dctx->dbiter);
        result = DNS_R_CONTINUE;
    } else if (result == ISC_R_NOMORE)
        result = ISC_R_SUCCESS;
 fail:
    isc_mem_put(dctx->mctx, buffer.base, buffer.length);
    return (result);
}

isc_result_t
dns_master_dumptostreaminc(isc_mem_t *mctx, dns_db_t *db,
               dns_dbversion_t *version,
               const dns_master_style_t *style,
               FILE *f, isc_task_t *task,
               dns_dumpdonefunc_t done, void *done_arg,
               dns_dumpctx_t **dctxp)
{
    dns_dumpctx_t *dctx = NULL;
    isc_result_t result;

    REQUIRE(task != NULL);
    REQUIRE(f != NULL);
    REQUIRE(done != NULL);

    result = dumpctx_create(mctx, db, version, style, f, &dctx);
    if (result != ISC_R_SUCCESS)
        return (result);
    isc_task_attach(task, &dctx->task);
    dctx->done = done;
    dctx->done_arg = done_arg;
    dctx->nodes = 100;

    result = task_send(dctx);
    if (result == ISC_R_SUCCESS) {
        dns_dumpctx_attach(dctx, dctxp);
        return (DNS_R_CONTINUE);
    }
    if (dctx != NULL)
        dns_dumpctx_detach(&dctx);

    return (result);
}

/*
 * Dump an entire database into a master file.
 */
isc_result_t
dns_master_dumptostream(isc_mem_t *mctx, dns_db_t *db,
            dns_dbversion_t *version,
            const dns_master_style_t *style,
            FILE *f)
{
    dns_dumpctx_t *dctx = NULL;
    isc_result_t result;

    result = dumpctx_create(mctx, db, version, style, f, &dctx);
    if (result != ISC_R_SUCCESS)
        return (result);

    result = dumptostreaminc(dctx);
    INSIST(result != DNS_R_CONTINUE);
    dns_dumpctx_detach(&dctx);
    return (result);
}

static isc_result_t
opentmp(isc_mem_t *mctx, const char *file, char **tempp, FILE **fp) {
    FILE *f = NULL;
    isc_result_t result;
    char *tempname = NULL;
    int tempnamelen;

    tempnamelen = strlen(file) + 20;
    tempname = isc_mem_allocate(mctx, tempnamelen);
    if (tempname == NULL)
        return (ISC_R_NOMEMORY);

    result = isc_file_mktemplate(file, tempname, tempnamelen);
    if (result != ISC_R_SUCCESS)
        goto cleanup;

    result = isc_file_openunique(tempname, &f);
    if (result != ISC_R_SUCCESS) {
        isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                  DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                  "dumping master file: %s: open: %s",
                  tempname, isc_result_totext(result));
        goto cleanup;
    }
    *tempp = tempname;
    *fp = f;
    return (ISC_R_SUCCESS);

cleanup:
    isc_mem_free(mctx, tempname);
    return (result);
}

isc_result_t
dns_master_dumpinc(isc_mem_t *mctx, dns_db_t *db, dns_dbversion_t *version,
           const dns_master_style_t *style, const char *filename,
           isc_task_t *task, dns_dumpdonefunc_t done, void *done_arg,
           dns_dumpctx_t **dctxp)
{
    FILE *f = NULL;
    isc_result_t result;
    char *tempname = NULL;
    char *file = NULL;
    dns_dumpctx_t *dctx = NULL;

    file = isc_mem_strdup(mctx, filename);
    if (file == NULL)
        return (ISC_R_NOMEMORY);

    result = opentmp(mctx, filename, &tempname, &f);
    if (result != ISC_R_SUCCESS)
        goto cleanup;

    result = dumpctx_create(mctx, db, version, style, f, &dctx);
    if (result != ISC_R_SUCCESS) {
        (void)isc_stdio_close(f);
        (void)isc_file_remove(tempname);
        goto cleanup;
    }

    isc_task_attach(task, &dctx->task);
    dctx->done = done;
    dctx->done_arg = done_arg;
    dctx->nodes = 100;
    dctx->file = file;
    file = NULL;
    dctx->tmpfile = tempname;
    tempname = NULL;

    result = task_send(dctx);
    if (result == ISC_R_SUCCESS) {
        dns_dumpctx_attach(dctx, dctxp);
        return (DNS_R_CONTINUE);
    }

 cleanup:
    if (dctx != NULL)
        dns_dumpctx_detach(&dctx);
    if (file != NULL)
        isc_mem_free(mctx, file);
    if (tempname != NULL)
        isc_mem_free(mctx, tempname);
    return (result);
}

isc_result_t
dns_master_dump(isc_mem_t *mctx, dns_db_t *db, dns_dbversion_t *version,
        const dns_master_style_t *style, const char *filename)
{
    FILE *f = NULL;
    isc_result_t result;
    char *tempname;
    dns_dumpctx_t *dctx = NULL;

    result = opentmp(mctx, filename, &tempname, &f);
    if (result != ISC_R_SUCCESS)
        return (result);

    result = dumpctx_create(mctx, db, version, style, f, &dctx);
    if (result != ISC_R_SUCCESS)
        goto cleanup;

    result = dumptostreaminc(dctx);
    INSIST(result != DNS_R_CONTINUE);
    dns_dumpctx_detach(&dctx);

    result = closeandrename(f, result, tempname, filename);

 cleanup:
    isc_mem_free(mctx, tempname);
    return (result);
}

/*
 * Dump a database node into a master file.
 */
isc_result_t
dns_master_dumpnodetostream(isc_mem_t *mctx, dns_db_t *db,
                dns_dbversion_t *version,
                dns_dbnode_t *node, dns_name_t *name,
                const dns_master_style_t *style,
                FILE *f)
{
    isc_result_t result;
    isc_buffer_t buffer;
    char *bufmem;
    isc_stdtime_t now;
    dns_totext_ctx_t ctx;
    dns_rdatasetiter_t *rdsiter = NULL;

    result = totext_ctx_init(style, &ctx);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "could not set master file style");
        return (ISC_R_UNEXPECTED);
    }

    isc_stdtime_get(&now);

    bufmem = isc_mem_get(mctx, initial_buffer_length);
    if (bufmem == NULL)
        return (ISC_R_NOMEMORY);

    isc_buffer_init(&buffer, bufmem, initial_buffer_length);

    result = dns_db_allrdatasets(db, node, version, now, &rdsiter);
    if (result != ISC_R_SUCCESS)
        goto failure;
    result = dump_rdatasets(mctx, name, rdsiter, &ctx, &buffer, f);
    if (result != ISC_R_SUCCESS)
        goto failure;
    dns_rdatasetiter_destroy(&rdsiter);

    result = ISC_R_SUCCESS;

 failure:
    isc_mem_put(mctx, buffer.base, buffer.length);
    return (result);
}

isc_result_t
dns_master_dumpnode(isc_mem_t *mctx, dns_db_t *db, dns_dbversion_t *version,
            dns_dbnode_t *node, dns_name_t *name,
            const dns_master_style_t *style, const char *filename)
{
    FILE *f = NULL;
    isc_result_t result;

    result = isc_stdio_open(filename, "w", &f);
    if (result != ISC_R_SUCCESS) {
        isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                  DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                  "dumping node to file: %s: open: %s", filename,
                  isc_result_totext(result));
        return (ISC_R_UNEXPECTED);
    }

    result = dns_master_dumpnodetostream(mctx, db, version, node, name,
                         style, f);

    result = isc_stdio_close(f);
    if (result != ISC_R_SUCCESS) {
        isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                  DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                  "dumping master file: %s: close: %s", filename,
                  isc_result_totext(result));
        return (ISC_R_UNEXPECTED);
    }

    return (result);
}

isc_result_t
dns_master_stylecreate(dns_master_style_t **stylep, unsigned int flags,
                       unsigned int ttl_column, unsigned int class_column,
                       unsigned int type_column, unsigned int rdata_column,
                       unsigned int line_length, unsigned int tab_width,
                       isc_mem_t *mctx)
{
    dns_master_style_t *style;

    REQUIRE(stylep != NULL && *stylep == NULL);
    style = isc_mem_get(mctx, sizeof(*style));
    if (style == NULL)
        return (ISC_R_NOMEMORY);

    style->flags = flags;
    style->ttl_column = ttl_column;
    style->class_column = class_column;
    style->type_column = type_column;
    style->rdata_column = rdata_column;
    style->line_length = line_length;
    style->tab_width = tab_width;

    *stylep = style;
    return (ISC_R_SUCCESS);
}

void
dns_master_styledestroy(dns_master_style_t **stylep, isc_mem_t *mctx) {
    dns_master_style_t *style;

    REQUIRE(stylep != NULL && *stylep != NULL);
    style = *stylep;
    *stylep = NULL;
    isc_mem_put(mctx, style, sizeof(*style));
}