/*
 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * Permission to use, copy, modify, and/or 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.
 */

/*! \file */

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

#include <isc/types.h>
#include <isc/util.h>

#include <dns/fixedname.h>
#include <dns/masterdump.h>
#include <dns/rdata.h>
#include <dns/rdataclass.h>
#include <dns/rdataset.h>
#include <dns/rdatatype.h>
#include <dns/result.h>

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

struct dns_master_style {
        dns_masterstyle_flags_t 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;
        unsigned int split_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;
        int             class_printed;
        char *                  linebreak;
        char                    linebreak_buf[DNS_TOTEXT_LINEBREAK_MAXLEN];
        dns_name_t *            origin;
        dns_name_t *            neworigin;
        dns_fixedname_t         origin_fixname;
        uint32_t                current_ttl;
        int             current_ttl_valid;
} dns_totext_ctx_t;

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

#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";

/*%
 * 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;
                        memmove(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;
                memmove(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 = 0;

        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);

                if ((ctx->style.flags & DNS_STYLEFLAG_COMMENTDATA) != 0) {
                        isc_buffer_availableregion(&buf, &r);
                        if (r.length < 1)
                                return (DNS_R_TEXTTOOLONG);
                        r.base[0] = ';';
                        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 indefinitely 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 = 0;

        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)

/*
 * 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,
                int omit_final_dot,
                isc_buffer_t *target)
{
        isc_result_t result;
        unsigned int column;
        int first = 1;
        uint32_t current_ttl;
        int current_ttl_valid;
        dns_rdatatype_t type;
        unsigned int type_start;

        result = dns_rdataset_first(rdataset);

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

        while (result == ISC_R_SUCCESS) {
                column = 0;

                /*
                 * Comment?
                 */
                if ((ctx->style.flags & DNS_STYLEFLAG_COMMENTDATA) != 0)
                        RETERR(isc_str_tobuffer(";", target));

                /*
                 * 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);
                        memmove(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 = 1;
                        }
                }

                /*
                 * Class.
                 */
                if ((ctx->style.flags & DNS_STYLEFLAG_NO_CLASS) == 0 &&
                    ((ctx->style.flags & DNS_STYLEFLAG_OMIT_CLASS) == 0 ||
                     !ctx->class_printed))
                {
                        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.
                 */

                type = rdataset->type;

                INDENT_TO(type_column);
                type_start = target->used;
                switch (type) {
                case dns_rdatatype_keydata:
#define KEYDATA "KEYDATA"
                        if ((ctx->style.flags & DNS_STYLEFLAG_KEYDATA) != 0) {
                                if (isc_buffer_availablelength(target) <
                                    (sizeof(KEYDATA) - 1))
                                        return (ISC_R_NOSPACE);
                                isc_buffer_putstr(target, KEYDATA);
                                break;
                        }
                        /* FALLTHROUGH */
                default:
                        result = dns_rdatatype_totext(type, target);
                        if (result != ISC_R_SUCCESS)
                                return (result);
                }
                column += (target->used - type_start);

                /*
                 * Rdata.
                 */
                INDENT_TO(rdata_column);
                {
                        dns_rdata_t rdata = DNS_RDATA_INIT;
                        isc_region_t r;

                        dns_rdataset_current(rdataset, &rdata);

                        RETERR(dns_rdata_tofmttext(&rdata,
                                                   ctx->origin,
                                                   (unsigned int)
                                                   ctx->style.flags,
                                                   ctx->style.line_length -
                                                       ctx->style.rdata_column,
                                                   ctx->style.split_width,
                                                   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 = 0;
                result = dns_rdataset_next(rdataset);
        }

        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 = 1;
        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,
                int omit_final_dot,
                isc_buffer_t *target)
{
        unsigned int column;
        isc_result_t result;
        isc_region_t r;

        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,
                    int omit_final_dot,
                    int 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,
                                0, 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,
                                0, target));
}

isc_result_t
dns_master_stylecreate2(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,
                        unsigned int split_width)
{
        dns_master_style_t *style;

        REQUIRE(stylep != NULL && *stylep == NULL);
        style = malloc(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;
        style->split_width = split_width;

        *stylep = style;
        return (ISC_R_SUCCESS);
}

void
dns_master_styledestroy(dns_master_style_t **stylep) {
        dns_master_style_t *style;

        REQUIRE(stylep != NULL && *stylep != NULL);
        style = *stylep;
        *stylep = NULL;
        free(style);
}