lib/dns/master.c

	master.c revision 7d32c065c7bb56f281651ae3dd2888f32ce4f1d9
/*
 * Copyright (C) 1999, 2000  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

 /* $Id: master.c,v 1.39 2000/02/03 23:43:49 halley Exp $ */

#include <config.h>

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <limits.h>
#include <time.h>

#include <isc/lex.h>
#include <isc/list.h>
#include <isc/mem.h>
#include <isc/assertions.h>
#include <isc/error.h>
#include <isc/stdtime.h>

#include <dns/master.h>
#include <dns/types.h>
#include <dns/result.h>
#include <dns/rdatalist.h>
#include <dns/rdataset.h>
#include <dns/rdataclass.h>
#include <dns/rdatatype.h>
#include <dns/rdata.h>
#include <dns/time.h>
#include <dns/ttl.h>

/*
 * Grow the number of dns_rdatalist_t (RDLSZ) and dns_rdata_t (RDSZ) structures
 * by these sizes when we need to.
 *
 * RDLSZ reflects the number of different types with the same name expected.
 * RDSZ reflects the number of rdata expected at a give name that can fit into
 * 64k.
 */

#define RDLSZ 32
#define RDSZ 512

#define NBUFS 4
#define MAXWIRESZ 255

/*
 * Target buffer size and minimum target size.
 * MINTSIZ must be big enough to hold the largest rdata record.
 *
 * TSIZ >= MINTSIZ
 */
#define TSIZ (128*1024)
/*
 * max message size - header - root - type - class - ttl - rdlen
 */
#define MINTSIZ (65535 - 12 - 1 - 2 - 2 - 4 - 2)
/*
 * Size for tokens in the presentation format,
 * The largest tokens are the base64 blocks in KEY and CERT records,
 * Largest key allowed is about 1372 bytes but
 * there is no fixed upper bound on Cert records
 * 2K is too small for some X.509's 8K is an overkill
 */
#define TOKENSIZ (8*1024)

typedef ISC_LIST(dns_rdatalist_t) rdatalist_head_t;

static isc_result_t commit(dns_rdatacallbacks_t *, rdatalist_head_t *,
                   dns_name_t *);
static isc_boolean_t    is_glue(rdatalist_head_t *, dns_name_t *);
static dns_rdatalist_t  *grow_rdatalist(int, dns_rdatalist_t *, int,
                        rdatalist_head_t *,
                    rdatalist_head_t *,
                    isc_mem_t *mctx);
static dns_rdata_t  *grow_rdata(int, dns_rdata_t *, int,
                    rdatalist_head_t *, rdatalist_head_t *,
                    isc_mem_t *);
static isc_boolean_t    on_list(dns_rdatalist_t *this, dns_rdata_t *rdata);

#define GETTOKEN(lexer, options, token, eol) \
    do { \
        result = gettoken(lexer, options, token, eol, callbacks); \
        switch (result) { \
        case DNS_R_SUCCESS: \
            break; \
        case DNS_R_UNEXPECTED: \
            goto cleanup; \
        default: \
            goto error_cleanup; \
        } \
    } while (0) \

static inline isc_result_t
gettoken(isc_lex_t *lex, unsigned int options, isc_token_t *token,
     isc_boolean_t eol, dns_rdatacallbacks_t *callbacks)
{
    isc_result_t result;

    options |= ISC_LEXOPT_EOL | ISC_LEXOPT_EOF | ISC_LEXOPT_DNSMULTILINE |
        ISC_LEXOPT_ESCAPE;
    result = isc_lex_gettoken(lex, options, token);
    if (result != ISC_R_SUCCESS) {
        switch (result) {
        case ISC_R_NOMEMORY:
            return (DNS_R_NOMEMORY);
        default:
            UNEXPECTED_ERROR(__FILE__, __LINE__,
                "isc_lex_gettoken() failed: %s",
                isc_result_totext(result));
            return (DNS_R_UNEXPECTED);
        }
        /*NOTREACHED*/
    }
    if (eol != ISC_TRUE)
        if (token->type == isc_tokentype_eol ||
            token->type == isc_tokentype_eof) {
            (*callbacks->error)(callbacks,
                "dns_master_load: %s:%d: unexpected end of %s",
                        isc_lex_getsourcename(lex),
                        isc_lex_getsourceline(lex),
                        (token->type ==
                         isc_tokentype_eol) ?
                        "line" : "file");
            return (DNS_R_UNEXPECTEDEND);
        }
    return (DNS_R_SUCCESS);
}

static isc_result_t
load(isc_lex_t *lex, dns_name_t *top, dns_name_t *origin,
     dns_rdataclass_t zclass, isc_boolean_t age_ttl,
     int *soacount, int *nscount, dns_rdatacallbacks_t *callbacks,
     isc_mem_t *mctx)
{
    dns_rdataclass_t rdclass;
    dns_rdatatype_t type, covers;
    isc_uint32_t ttl = 0;
    isc_uint32_t default_ttl = 0;
    isc_uint32_t ttl_offset = 0;
    dns_name_t current_name;
    dns_name_t glue_name;
    dns_name_t new_name;
    dns_name_t origin_name = *origin;
    isc_boolean_t ttl_known = ISC_FALSE;
    isc_boolean_t default_ttl_known = ISC_FALSE;
    isc_boolean_t current_known = ISC_FALSE;
    isc_boolean_t in_glue = ISC_FALSE;
    isc_boolean_t current_has_delegation = ISC_FALSE;
    isc_boolean_t done = ISC_FALSE;
    isc_boolean_t finish_origin = ISC_FALSE;
    isc_boolean_t finish_include = ISC_FALSE;
    isc_boolean_t read_till_eol = ISC_FALSE;
    isc_boolean_t warn_1035 = ISC_TRUE; /* XXX Arguement? */
    char *include_file = NULL;
    isc_token_t token;
    isc_result_t result = DNS_R_UNEXPECTED;
    rdatalist_head_t glue_list;
    rdatalist_head_t current_list;
    dns_rdatalist_t *this;
    dns_rdatalist_t *rdatalist = NULL;
    dns_rdatalist_t *new_rdatalist;
    int rdlcount = 0;
    int rdlcount_save = 0;
    int rdatalist_size = 0;
    isc_buffer_t buffer;
    isc_buffer_t target;
    isc_buffer_t target_save;
    dns_rdata_t *rdata = NULL;
    dns_rdata_t *new_rdata;
    int rdcount = 0;
    int rdcount_save = 0;
    int rdata_size = 0;
    unsigned char *target_mem = NULL;
    int target_size = TSIZ;
    unsigned char name_buf[NBUFS][MAXWIRESZ];
    isc_boolean_t name_in_use[NBUFS];
    int glue_in_use = -1;
    int current_in_use = -1;
    int origin_in_use = -1;
    int new_in_use;
    isc_buffer_t name;
    isc_lexspecials_t specials;

    REQUIRE(lex != NULL);
    REQUIRE(dns_name_isabsolute(top));
    REQUIRE(dns_name_isabsolute(origin));
    REQUIRE(callbacks != NULL);
    REQUIRE(callbacks->add != NULL);
    REQUIRE(callbacks->error != NULL);
    REQUIRE(callbacks->warn != NULL);
    REQUIRE(nscount != NULL);
    REQUIRE(soacount != NULL);
    REQUIRE(mctx != NULL);

    dns_name_init(&current_name, NULL);
    dns_name_init(&glue_name, NULL);

    ISC_LIST_INIT(glue_list);
    ISC_LIST_INIT(current_list);

    memset(specials, 0, sizeof specials);
    specials['('] = 1;
    specials[')'] = 1;
    specials['"'] = 1;
    isc_lex_setspecials(lex, specials);
    isc_lex_setcomments(lex, ISC_LEXCOMMENT_DNSMASTERFILE);

    /*
     * Allocate target_size of buffer space.  This is greater than twice
     * the maximum individual RR data size.
     */
    target_mem = isc_mem_get(mctx, target_size);
    if (target_mem == NULL) {
        result = DNS_R_NOMEMORY;
        goto error_cleanup;
    }
    isc_buffer_init(&target, target_mem, target_size,
            ISC_BUFFERTYPE_BINARY);
    target_save = target;

    memset(name_in_use, 0, NBUFS * sizeof(isc_boolean_t));

    do {
        GETTOKEN(lex, ISC_LEXOPT_INITIALWS, &token, ISC_TRUE);

        if (token.type == isc_tokentype_eof) {
            done = ISC_TRUE;
            continue;
        }

        if (token.type == isc_tokentype_eol) {
            read_till_eol = ISC_FALSE;
            continue;       /* blank line */
        }

        if (read_till_eol)
            continue;

        if (token.type == isc_tokentype_initialws) {
            if (!current_known) {
                (*callbacks->error)(callbacks,
                    "%s: %s:%d: No current owner name",
                        "dns_master_load",
                        isc_lex_getsourcename(lex),
                        isc_lex_getsourceline(lex));
                result = DNS_R_NOOWNER;
                goto cleanup;
            }
            /* Still working on the same name. */
        } else if (token.type == isc_tokentype_string) {

            /*
             * "$" Support.
             *
             * "$ORIGIN" and "$INCLUDE" can both take domain names.
             * The processing of "$ORIGIN" and "$INCLUDE" extends
             * across the normal domain name processing.
             */

            if (strcasecmp(token.value.as_pointer,
                       "$ORIGIN") == 0) {
                GETTOKEN(lex, 0, &token, ISC_FALSE);
                read_till_eol = ISC_TRUE;
                finish_origin = ISC_TRUE;
            } else if (strcasecmp(token.value.as_pointer,
                              "$TTL") == 0) {
                GETTOKEN(lex, 0, &token, ISC_FALSE);
                result =
                    dns_ttl_fromtext(&token.value.as_textregion,
                             &ttl);
                if (result != DNS_R_SUCCESS)
                    goto cleanup;
                if (ttl > 0x7fffffffUL) {
                    (callbacks->warn)(callbacks,
        "dns_master_load: %s:%d: $TTL %lu > MAXTLL, setting TTL to 0",
                        isc_lex_getsourcename(lex),
                        isc_lex_getsourceline(lex),
                        ttl);
                    ttl = 0;
                }
                default_ttl = ttl;
                default_ttl_known = ISC_TRUE;
                read_till_eol = ISC_TRUE;
                continue;
            } else if (strcasecmp(token.value.as_pointer,
                          "$INCLUDE") == 0) {
                if (ttl_offset != 0) {
                    (callbacks->error)(callbacks,
                       "dns_master_load: %s:%d: $INCLUDE "
                       "may not be used with $DATE",
                       isc_lex_getsourcename(lex),
                       isc_lex_getsourceline(lex));
                    goto cleanup;
                }
                GETTOKEN(lex, 0, &token, ISC_FALSE);
                if (include_file != NULL)
                    isc_mem_free(mctx, include_file);
                include_file = isc_mem_strdup(mctx,
                        token.value.as_pointer);
                if (include_file == NULL) {
                    result = DNS_R_NOMEMORY;
                    goto error_cleanup;
                }
                GETTOKEN(lex, 0, &token, ISC_TRUE);
                if (token.type == isc_tokentype_eol ||
                    token.type == isc_tokentype_eof) {
                    result =
                        dns_master_loadfile(include_file,
                                top,
                                &origin_name,
                                zclass,
                                age_ttl,
                                soacount,
                                nscount,
                                callbacks,
                                mctx);
                    if (result != DNS_R_SUCCESS)
                        goto cleanup;
                    isc_lex_ungettoken(lex, &token);
                    continue;
                }
                read_till_eol = ISC_TRUE;
                finish_include = ISC_TRUE;
            } else if (strcasecmp(token.value.as_pointer,
                          "$DATE") == 0) {
                isc_int64_t dump_time64;
                isc_stdtime_t dump_time, current_time;
                GETTOKEN(lex, 0, &token, ISC_FALSE);
                isc_stdtime_get(&current_time);
                result = dns_time64_fromtext(token.value.
                         as_pointer, &dump_time64);
                if (result != ISC_R_SUCCESS)
                    goto error_cleanup;
                dump_time = (isc_stdtime_t)dump_time64;
                if (dump_time != dump_time64) {
                    UNEXPECTED_ERROR(__FILE__, __LINE__,
                     "dns_master_load: %s:%d: "
                     "$DATE outside epoch",
                     isc_lex_getsourcename(lex),
                     isc_lex_getsourceline(lex));
                    goto cleanup;
                }
                if (dump_time > current_time) {
                    UNEXPECTED_ERROR(__FILE__, __LINE__,
                    "dns_master_load: %s:%d: "
                    "$DATE in future, using current date",
                    isc_lex_getsourcename(lex),
                    isc_lex_getsourceline(lex));
                    dump_time = current_time;
                }
                ttl_offset = current_time - dump_time;
                read_till_eol = ISC_TRUE;
                continue;
            } else if (strncasecmp(token.value.as_pointer,
                           "$", 1) == 0) {
                (callbacks->error)(callbacks,
                           "dns_master_load: %s %d "
                           "UNKOWN $<DIRECTIVE> %s ",
                           isc_lex_getsourcename(lex),
                           isc_lex_getsourceline(lex),
                           token.value.as_pointer);
                goto cleanup;
            }

            /*
             * Normal processing resumes.
             *
             * Find a free name buffer.
             */
            for (new_in_use = 0; new_in_use < NBUFS ; new_in_use++)
                if (!name_in_use[new_in_use])
                    break;
            INSIST(new_in_use < NBUFS);
            isc_buffer_init(&name, &name_buf[new_in_use][0],
                    MAXWIRESZ, ISC_BUFFERTYPE_BINARY);
            dns_name_init(&new_name, NULL);
            isc_buffer_init(&buffer, token.value.as_region.base,
                    token.value.as_region.length,
                    ISC_BUFFERTYPE_TEXT);
            isc_buffer_add(&buffer, token.value.as_region.length);
            isc_buffer_setactive(&buffer,
                         token.value.as_region.length);
            result = dns_name_fromtext(&new_name, &buffer,
                      &origin_name, ISC_FALSE, &name);
            if (result != DNS_R_SUCCESS)
                goto error_cleanup;

            /*
             * Finish $ORIGIN / $INCLUDE processing if required.
             */
            if (finish_origin) {
                if (origin_in_use != -1)
                    name_in_use[origin_in_use] = ISC_FALSE;
                origin_in_use = new_in_use;
                name_in_use[origin_in_use] = ISC_TRUE;
                origin_name = new_name;
                finish_origin =ISC_FALSE;
                continue;
            }
            if (finish_include) {
                result = dns_master_loadfile(include_file,
                                 top,
                                 &new_name,
                                 zclass,
                                 age_ttl,
                                 soacount,
                                 nscount,
                                 callbacks,
                                 mctx);
                if (result != DNS_R_SUCCESS)
                    goto cleanup;
                finish_include = ISC_FALSE;
                continue;
            }

            /*
             * "$" Processing Finished
             */

            /*
             * If we are processing glue and the new name does
             * not match the current glue name, commit the glue
             * and pop stacks leaving us in 'normal' processing
             * state.  Linked lists are undone by commit().
             */
            if (in_glue && dns_name_compare(&glue_name,
                            &new_name) != 0) {
                result = commit(callbacks, &glue_list,
                        &glue_name);
                if (result != DNS_R_SUCCESS)
                    goto cleanup;
                if (glue_in_use != -1)
                    name_in_use[glue_in_use] = ISC_FALSE;
                glue_in_use = -1;
                dns_name_invalidate(&glue_name);
                in_glue = ISC_FALSE;
                rdcount = rdcount_save;
                rdlcount = rdlcount_save;
                target = target_save;
            }

            /*
             * If we are in 'normal' processing state and the new
             * name does not match the current name, see if the
             * new name is for glue and treat it as such,
             * otherwise we have a new name so commit what we
             * have.
             */
            if (!in_glue && (!current_known ||
                dns_name_compare(&current_name, &new_name) != 0)) {
                if (current_has_delegation &&
                    is_glue(&current_list, &new_name)) {
                    in_glue = ISC_TRUE;
                    rdcount_save = rdcount;
                    rdlcount_save = rdlcount;
                    target_save = target;
                    glue_name = new_name;
                    glue_in_use = new_in_use;
                    name_in_use[glue_in_use] = ISC_TRUE;
                } else {
                    result = commit(callbacks,
                            &current_list,
                            &current_name);
                    if (result != DNS_R_SUCCESS)
                        goto cleanup;
                    rdcount = 0;
                    rdlcount = 0;
                    if (current_in_use != -1)
                        name_in_use[current_in_use]
                            = ISC_FALSE;
                    current_in_use = new_in_use;
                    name_in_use[current_in_use] = ISC_TRUE;
                    current_name = new_name;
                    current_known = ISC_TRUE;
                    current_has_delegation = ISC_FALSE;
                    isc_buffer_init(&target, target_mem,
                            target_size,
                            ISC_BUFFERTYPE_BINARY);
                }
            }
        } else {
            UNEXPECTED_ERROR(__FILE__, __LINE__,
         "%s:%d: isc_lex_gettoken() returned unexpeced token type (%d)",
                     isc_lex_getsourcename(lex),
                     isc_lex_getsourceline(lex),
                     token.type);
            result = DNS_R_UNEXPECTED;
            goto cleanup;
        }

        /*
         * Find TTL, class and type.  Both TTL and class are optional
         * and may occur in any order if they exist. TTL and class
         * come before type which must exist.
         *
         * [<TTL>] [<class>] <type> <RDATA>
         * [<class>] [<TTL>] <type> <RDATA>
         */

        type = 0;
        rdclass = 0;

        GETTOKEN(lex, 0, &token, ISC_FALSE);

        if (dns_rdataclass_fromtext(&rdclass,
                        &token.value.as_textregion)
                == DNS_R_SUCCESS)
            GETTOKEN(lex, 0, &token, ISC_FALSE);

        if (dns_ttl_fromtext(&token.value.as_textregion, &ttl)
                == DNS_R_SUCCESS) {
            if (ttl > 0x7fffffffUL) {
                (callbacks->warn)(callbacks,
    "dns_master_load: %s:%d: TTL %lu > maxtll, setting ttl to 0",
                    isc_lex_getsourcename(lex),
                    isc_lex_getsourceline(lex),
                    ttl);
                ttl = 0;
            }
            ttl_known = ISC_TRUE;
            GETTOKEN(lex, 0, &token, ISC_FALSE);
        } else if (!ttl_known && !default_ttl_known) {
            /*
             * BIND 4 / 8 'USE_SOA_MINIMUM' could be set here.
             */
            (*callbacks->error)(callbacks,
                        "%s: %s:%d: no TTL specified",
                        "dns_master_load",
                        isc_lex_getsourcename(lex),
                        isc_lex_getsourceline(lex));
            result = DNS_R_NOTTL;
            goto cleanup;
        } else if (default_ttl_known) {
            ttl = default_ttl;
        } else if (warn_1035) {
            (*callbacks->warn)(callbacks,
                   "%s: %s:%d: using RFC 1035 TTL semantics",
                       "dns_master_load",
                       isc_lex_getsourcename(lex),
                       isc_lex_getsourceline(lex));
            warn_1035 = ISC_FALSE;
        }

        if (token.type != isc_tokentype_string) {
            UNEXPECTED_ERROR(__FILE__, __LINE__,
            "isc_lex_gettoken() returned unexpected token type");
            result = DNS_R_UNEXPECTED;
            goto cleanup;
        }

        if (rdclass == 0 &&
            dns_rdataclass_fromtext(&rdclass,
                        &token.value.as_textregion)
                == DNS_R_SUCCESS)
            GETTOKEN(lex, 0, &token, ISC_FALSE);

        if (token.type !=  isc_tokentype_string) {
            UNEXPECTED_ERROR(__FILE__, __LINE__,
            "isc_lex_gettoken() returned unexpected token type");
            result = DNS_R_UNEXPECTED;
            goto cleanup;
        }

        result = dns_rdatatype_fromtext(&type,
                        &token.value.as_textregion);
        if (result != DNS_R_SUCCESS)
            goto cleanup;

        /*
         * If the class specified does not match the zone's class
         * print out a error message and exit.
         */
        if (rdclass != 0 && rdclass != zclass) {
            char buf1[32];
            char buf2[32];
            unsigned int len1, len2;
            isc_buffer_t buffer;
            isc_region_t region;

            isc_buffer_init(&buffer, buf1, sizeof buf1,
                    ISC_BUFFERTYPE_TEXT);
            result = dns_rdataclass_totext(rdclass, &buffer);
            if (result != DNS_R_SUCCESS) {
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                    "dns_rdataclass_totext() failed: %s",
                         dns_result_totext(result));
                result = DNS_R_UNEXPECTED;
                goto cleanup;
            }
            isc_buffer_used(&buffer, &region);
            len1 = region.length;
            isc_buffer_init(&buffer, buf2, sizeof buf2,
                    ISC_BUFFERTYPE_TEXT);
            result = dns_rdataclass_totext(zclass, &buffer);
            if (result != DNS_R_SUCCESS) {
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                    "dns_rdataclass_totext() failed: %s",
                         dns_result_totext(result));
                result = DNS_R_UNEXPECTED;
                goto cleanup;
            }
            isc_buffer_used(&buffer, &region);
            len2 = region.length;
            (*callbacks->error)(callbacks,
                   "%s: %s:%d: class (%.*s) != zone class (%.*s)",
                        "dns_master_load",
                        isc_lex_getsourcename(lex),
                        isc_lex_getsourceline(lex),
                        len1, buf1, len2, buf2);
            result = DNS_R_BADCLASS;
            goto cleanup;
        }

        if (type == dns_rdatatype_ns && !in_glue)
            current_has_delegation = ISC_TRUE;

        if (age_ttl) {
            /*
             * Adjust the TTL for $DATE.  If the RR has already
             * expired, ignore it without even parsing the rdata
             * part (good for performance, bad for catching
             * syntax errors).
             */
            if (ttl < ttl_offset) {
                read_till_eol = ISC_TRUE;
                continue;
            }
            ttl -= ttl_offset;
        }

        /*
         * Find a rdata structure.
         */
        if (rdcount == rdata_size) {
            new_rdata = grow_rdata(rdata_size + RDSZ, rdata,
                           rdata_size, &current_list,
                           &glue_list, mctx);
            if (new_rdata == NULL) {
                result = DNS_R_NOMEMORY;
                goto error_cleanup;
            }
            rdata_size += RDSZ;
            rdata = new_rdata;
        }

        /*
         * Read rdata contents.
         */
        result = dns_rdata_fromtext(&rdata[rdcount], zclass, type,
                   lex, &origin_name, ISC_FALSE, &target,
                   callbacks);
        if (result != DNS_R_SUCCESS)
            goto cleanup;
        if (type == dns_rdatatype_sig)
            covers = dns_rdata_covers(&rdata[rdcount]);
        else
            covers = 0;


        /*
         * Find type in rdatalist.
         * If it does not exist create new one and prepend to list
         * as this will mimimise list traversal.
         */
        if (in_glue)
            this = ISC_LIST_HEAD(glue_list);
        else
            this = ISC_LIST_HEAD(current_list);

        while (this != NULL) {
            if (this->type == type && this->covers == covers)
                break;
            this = ISC_LIST_NEXT(this, link);
        }

        if (this == NULL) {
            if (rdlcount == rdatalist_size) {
                new_rdatalist =
                    grow_rdatalist(rdatalist_size + RDLSZ,
                               rdatalist,
                               rdatalist_size,
                               &current_list,
                               &glue_list,
                               mctx);
                if (new_rdatalist == NULL) {
                    result = DNS_R_NOMEMORY;
                    goto error_cleanup;
                }
                rdatalist = new_rdatalist;
                rdatalist_size += RDLSZ;
            }
            this = &rdatalist[rdlcount++];
            this->type = type;
            this->covers = covers;
            this->rdclass = zclass;
            this->ttl = ttl;
            ISC_LIST_INIT(this->rdata);
            ISC_LINK_INIT(this, link);
            if (in_glue)
                ISC_LIST_PREPEND(glue_list, this, link);
            else
                ISC_LIST_PREPEND(current_list, this, link);
        } else if (this->ttl != ttl) {
            (*callbacks->warn)(callbacks,
                   "%s: %s:%d: TTL set to prior TTL (%lu)",
                       "dns_master_load",
                       isc_lex_getsourcename(lex),
                       isc_lex_getsourceline(lex),
                       this->ttl);
            ttl = this->ttl;
        }

        /*
         * If the new rdata is not on the list add it.
         *
         * If the new rdata is on the list do not worry about
         * recovering the space it is using in target as it will be
         * recovered when we next call commit.  The worst that can
         * happen is that we make a few extra calls to commit.
         */

        if (!on_list(this, &rdata[rdcount])) {
            ISC_LIST_APPEND(this->rdata, &rdata[rdcount], link);
            rdcount++;
        }

        /*
         * We must have at least 64k as rdlen is 16 bits.
         * If we don't commit everything we have so far.
         */
        if ((target.length - target.used) < MINTSIZ) {
            result = commit(callbacks, &current_list,
                    &current_name);
            if (result != DNS_R_SUCCESS)
                goto cleanup;
            result = commit(callbacks, &glue_list, &glue_name);
            if (result != DNS_R_SUCCESS)
                goto cleanup;
            rdcount = 0;
            rdlcount = 0;
            if (glue_in_use != -1)
                name_in_use[glue_in_use] = ISC_FALSE;
            glue_in_use = -1;
            in_glue = ISC_FALSE;
            current_has_delegation = ISC_FALSE;
            isc_buffer_init(&target, target_mem, target_size,
                    ISC_BUFFERTYPE_BINARY);
        }
    } while (!done);
    /*
     * Commit what has not yet been committed.
     */
    result = commit(callbacks, &current_list, &current_name);
    if (result != DNS_R_SUCCESS)
        goto cleanup;
    result = commit(callbacks, &glue_list, &glue_name);
    if (result != DNS_R_SUCCESS)
        goto cleanup;
    else
        result = DNS_R_SUCCESS;
    goto cleanup;

 error_cleanup:
    (*callbacks->error)(callbacks, "dns_master_load: %s",
                dns_result_totext(result));

 cleanup:
    if (lex != NULL) {
        isc_lex_close(lex);
        isc_lex_destroy(&lex);
    }
    while ((this = ISC_LIST_HEAD(current_list)) != NULL)
        ISC_LIST_UNLINK(current_list, this, link);
    while ((this = ISC_LIST_HEAD(glue_list)) != NULL)
        ISC_LIST_UNLINK(glue_list, this, link);
    if (rdatalist != NULL)
        isc_mem_put(mctx, rdatalist,
                rdatalist_size * sizeof *rdatalist);
    if (rdata != NULL)
        isc_mem_put(mctx, rdata, rdata_size * sizeof *rdata);
    if (target_mem != NULL)
        isc_mem_put(mctx, target_mem, target_size);
    if (include_file != NULL)
        isc_mem_free(mctx, include_file);
    return (result);
}

isc_result_t
dns_master_loadfile(const char *master_file, dns_name_t *top,
            dns_name_t *origin,
            dns_rdataclass_t zclass, isc_boolean_t age_ttl,
            int *soacount, int *nscount,
            dns_rdatacallbacks_t *callbacks,
            isc_mem_t *mctx)
{
    isc_result_t result;
    isc_lex_t *lex = NULL;

    REQUIRE(master_file != NULL);

    result = isc_lex_create(mctx, TOKENSIZ, &lex);
    if (result != ISC_R_SUCCESS)
        return (result);

    result = isc_lex_openfile(lex, master_file);
    if (result != ISC_R_SUCCESS) {
        isc_lex_destroy(&lex);
        return (result);
    }

    return (load(lex, top, origin, zclass, age_ttl, soacount, nscount,
             callbacks, mctx));
}

isc_result_t
dns_master_loadstream(FILE *stream, dns_name_t *top, dns_name_t *origin,
              dns_rdataclass_t zclass, isc_boolean_t age_ttl,
              int *soacount, int *nscount,
              dns_rdatacallbacks_t *callbacks, isc_mem_t *mctx)
{
    isc_result_t result;
    isc_lex_t *lex = NULL;

    REQUIRE(stream != NULL);

    result = isc_lex_create(mctx, TOKENSIZ, &lex);
    if (result != ISC_R_SUCCESS)
        return (result);

    result = isc_lex_openstream(lex, stream);
    if (result != ISC_R_SUCCESS) {
        isc_lex_destroy(&lex);
        return (result);
    }

    return (load(lex, top, origin, zclass, age_ttl, soacount, nscount,
             callbacks, mctx));
}

isc_result_t
dns_master_loadbuffer(isc_buffer_t *buffer, dns_name_t *top,
              dns_name_t *origin, dns_rdataclass_t zclass,
              isc_boolean_t age_ttl,
              int *soacount, int *nscount,
              dns_rdatacallbacks_t *callbacks, isc_mem_t *mctx)
{
    isc_result_t result;
    isc_lex_t *lex = NULL;

    REQUIRE(buffer != NULL);

    result = isc_lex_create(mctx, TOKENSIZ, &lex);
    if (result != ISC_R_SUCCESS)
        return (result);

    result = isc_lex_openbuffer(lex, buffer);
    if (result != ISC_R_SUCCESS) {
        isc_lex_destroy(&lex);
        return (result);
    }

    return (load(lex, top, origin, zclass, age_ttl, soacount, nscount,
             callbacks, mctx));
}

/*
 * Grow the slab of dns_rdatalist_t structures.
 * Re-link glue and current list.
 */
static dns_rdatalist_t *
grow_rdatalist(int new_len, dns_rdatalist_t *old, int old_len,
           rdatalist_head_t *current, rdatalist_head_t *glue,
           isc_mem_t *mctx)
{
    dns_rdatalist_t *new;
    int rdlcount = 0;
    ISC_LIST(dns_rdatalist_t) save;
    dns_rdatalist_t *this;

    new = isc_mem_get(mctx, new_len * sizeof *new);
    if (new == NULL)
        return (NULL);

    ISC_LIST_INIT(save);
    this = ISC_LIST_HEAD(*current);
    while ((this = ISC_LIST_HEAD(*current)) != NULL) {
        ISC_LIST_UNLINK(*current, this, link);
        ISC_LIST_APPEND(save, this, link);
    }
    while ((this = ISC_LIST_HEAD(save)) != NULL) {
        ISC_LIST_UNLINK(save, this, link);
        new[rdlcount] = *this;
        ISC_LIST_APPEND(*current, &new[rdlcount], link);
        rdlcount++;
    }

    ISC_LIST_INIT(save);
    this = ISC_LIST_HEAD(*glue);
    while ((this = ISC_LIST_HEAD(*glue)) != NULL) {
        ISC_LIST_UNLINK(*glue, this, link);
        ISC_LIST_APPEND(save, this, link);
    }
    while ((this = ISC_LIST_HEAD(save)) != NULL) {
        ISC_LIST_UNLINK(save, this, link);
        new[rdlcount] = *this;
        ISC_LIST_APPEND(*glue, &new[rdlcount], link);
        rdlcount++;
    }

    INSIST(rdlcount == old_len);
    if (old != NULL)
        isc_mem_put(mctx, old, old_len * sizeof *old);
    return (new);
}

/*
 * Grow the slab of rdata structs.
 * Re-link the current and glue chains.
 */
static dns_rdata_t *
grow_rdata(int new_len, dns_rdata_t *old, int old_len,
       rdatalist_head_t *current, rdatalist_head_t *glue,
       isc_mem_t *mctx)
{
    dns_rdata_t *new;
    int rdcount = 0;
    ISC_LIST(dns_rdata_t) save;
    dns_rdatalist_t *this;
    dns_rdata_t *rdata;

    new = isc_mem_get(mctx, new_len * sizeof *new);
    if (new == NULL)
        return (NULL);
    memset(new, 0, new_len * sizeof *new);

    /*
     * Copy current relinking.
     */
    this = ISC_LIST_HEAD(*current);
    while (this != NULL) {
        ISC_LIST_INIT(save);
        while ((rdata = ISC_LIST_HEAD(this->rdata)) != NULL) {
            ISC_LIST_UNLINK(this->rdata, rdata, link);
            ISC_LIST_APPEND(save, rdata, link);
        }
        while ((rdata = ISC_LIST_HEAD(save)) != NULL) {
            ISC_LIST_UNLINK(save, rdata, link);
            new[rdcount] = *rdata;
            ISC_LIST_APPEND(this->rdata, &new[rdcount], link);
            rdcount++;
        }
        this = ISC_LIST_NEXT(this, link);
    }

    /*
     * Copy glue relinking.
     */
    this = ISC_LIST_HEAD(*glue);
    while (this != NULL) {
        ISC_LIST_INIT(save);
        while ((rdata = ISC_LIST_HEAD(this->rdata)) != NULL) {
            ISC_LIST_UNLINK(this->rdata, rdata, link);
            ISC_LIST_APPEND(save, rdata, link);
        }
        while ((rdata = ISC_LIST_HEAD(save)) != NULL) {
            ISC_LIST_UNLINK(save, rdata, link);
            new[rdcount] = *rdata;
            ISC_LIST_APPEND(this->rdata, &new[rdcount], link);
            rdcount++;
        }
        this = ISC_LIST_NEXT(this, link);
    }
    INSIST(rdcount == old_len);
    if (old != NULL)
        isc_mem_put(mctx, old, old_len * sizeof *old);
    return (new);
}

/*
 * Convert each element from a rdatalist_t to rdataset then call commit.
 * Unlink each element as we go.
 */

static isc_result_t
commit(dns_rdatacallbacks_t *callbacks, rdatalist_head_t *head,
       dns_name_t *owner)
{
    dns_rdatalist_t *this;
    dns_rdataset_t dataset;
    isc_result_t result;

    while ((this = ISC_LIST_HEAD(*head)) != NULL) {
        dns_rdataset_init(&dataset);
        dns_rdatalist_tordataset(this, &dataset);
        result = ((*callbacks->add)(callbacks->add_private, owner,
                        &dataset));
        if (result != DNS_R_SUCCESS)
            return (result);
        ISC_LIST_UNLINK(*head, this, link);
    }
    return (DNS_R_SUCCESS);
}

/*
 * Returns ISC_TRUE if one of the NS rdata's contains 'owner'.
 */

static isc_boolean_t
is_glue(rdatalist_head_t *head, dns_name_t *owner) {
    dns_rdatalist_t *this;
    dns_rdata_t *rdata;
    isc_region_t region;
    dns_name_t name;

    /* find NS rrset */
    this = ISC_LIST_HEAD(*head);
    while (this != NULL) {
        if (this->type == dns_rdatatype_ns)
            break;
        this = ISC_LIST_NEXT(this, link);
    }
    if (this == NULL)
        return (ISC_FALSE);

    rdata = ISC_LIST_HEAD(this->rdata);
    while (rdata != NULL) {
        dns_name_init(&name, NULL);
        dns_rdata_toregion(rdata, &region);
        dns_name_fromregion(&name, &region);
        if (dns_name_compare(&name, owner) == 0)
            return (ISC_TRUE);
        rdata = ISC_LIST_NEXT(rdata, link);
    }
    return (ISC_FALSE);
}

/*
 * Returns ISC_TRUE if the 'rdata' is already on 'rdatalist'.
 */

static isc_boolean_t
on_list(dns_rdatalist_t *rdatalist, dns_rdata_t *rdata) {
    dns_rdata_t *rdata2;

    rdata2 = ISC_LIST_HEAD(rdatalist->rdata);
    while (rdata2 != NULL) {
        if (dns_rdata_compare(rdata, rdata2) == 0)
            return (ISC_TRUE);
        rdata2 = ISC_LIST_NEXT(rdata2, link);
    }
    return (ISC_FALSE);
}