lib/dns/rdataslab.c

	rdataslab.c revision da41917c3f882b6e12c7101b653926830a396b81
/*
 * 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: rdataslab.c,v 1.19 2000/09/01 19:59:35 gson Exp $ */

#include <config.h>

#include <stdlib.h>

#include <isc/mem.h>
#include <isc/region.h>
#include <isc/string.h>     /* Required for HP/UX (and others?) */
#include <isc/util.h>

#include <dns/result.h>
#include <dns/rdata.h>
#include <dns/rdataset.h>
#include <dns/rdataslab.h>

/* Note: the "const void *" are just to make qsort happy. */
static int
compare_rdata(const void *p1, const void *p2) {
    const dns_rdata_t *rdata1 = p1;
    const dns_rdata_t *rdata2 = p2;
    int len = ISC_MIN(rdata1->length, rdata2->length);
    int n;

    n = memcmp(rdata1->data, rdata2->data, len);
    if (n != 0)
        return (n);
    return (rdata1->length - rdata2->length);
}

isc_result_t
dns_rdataslab_fromrdataset(dns_rdataset_t *rdataset, isc_mem_t *mctx,
               isc_region_t *region, unsigned int reservelen)
{
    dns_rdata_t    *rdatas;
    unsigned char  *rawbuf;
    unsigned int    buflen;
    isc_result_t    result;
    unsigned int    nitems;
    unsigned int    nalloc;
    unsigned int    i;

    buflen = reservelen + 2;

    nalloc = dns_rdataset_count(rdataset);
    nitems = nalloc;

    rdatas = isc_mem_get(mctx, nalloc * sizeof(dns_rdata_t));
    if (rdatas == NULL)
        return (ISC_R_NOMEMORY);

    /*
     * Save all of the rdata members into an array.
     */
    result = dns_rdataset_first(rdataset);
    INSIST(result == ISC_R_SUCCESS);
    for (i = 0; i < nalloc; i++) {
        INSIST(result == ISC_R_SUCCESS);
        dns_rdataset_current(rdataset, &rdatas[i]);
        result = dns_rdataset_next(rdataset);
    }
    INSIST(result == ISC_R_NOMORE);

    qsort(rdatas, nalloc, sizeof(dns_rdata_t), compare_rdata);

    /*
     * Remove duplicates.
     */
    for (i = 1; i < nalloc; i++) {
        if (compare_rdata(&rdatas[i-1], &rdatas[i]) == 0) {
            rdatas[i-1].data = NULL;
            rdatas[i-1].length = 0;
            nitems--;
        }
    }

    /*
     * Run through the rdataset list once, counting up the size
     * of all the rdata members within it.  We do not store the
     * class, type, etc, just the rdata, so our overhead is 2 bytes
     * for the number of records, and 2 for each rdata length, and
     * then the rdata itself.
     */
    for (i = 0; i < nalloc; i++) {
        if (rdatas[i].data != NULL)
            buflen += (2 + rdatas[i].length);
        result = dns_rdataset_next(rdataset);
    }

    if (result != ISC_R_NOMORE) {
        isc_mem_put(mctx, rdatas, nalloc * sizeof(dns_rdata_t));
        return (result);
    }

    /*
     * Allocate the memory, set up a buffer, start copying in
     * data.
     */
    rawbuf = isc_mem_get(mctx, buflen);
    if (rawbuf == NULL) {
        result = ISC_R_NOMEMORY;
        goto free_rdatas;
    }

    region->base = rawbuf;
    region->length = buflen;

    rawbuf += reservelen;

    *rawbuf++ = (nitems & 0xff00) >> 8;
    *rawbuf++ = (nitems & 0x00ff);
    for (i = 0; i < nalloc; i++) {
        if (rdatas[i].data == NULL)
            continue;
        *rawbuf++ = (rdatas[i].length & 0xff00) >> 8;
        *rawbuf++ = (rdatas[i].length & 0x00ff);
        memcpy(rawbuf, rdatas[i].data, rdatas[i].length);
        rawbuf += rdatas[i].length;
    }
    result = ISC_R_SUCCESS;

 free_rdatas:
    isc_mem_put(mctx, rdatas, nalloc * sizeof(dns_rdata_t));
    return (result);
}

unsigned int
dns_rdataslab_size(unsigned char *slab, unsigned int reservelen) {
    unsigned int count, length;
    unsigned char *current;

    REQUIRE(slab != NULL);

    current = slab + reservelen;
    count = *current++ * 256;
    count += *current++;
    while (count > 0) {
        count--;
        length = *current++ * 256;
        length += *current++;
        current += length;
    }

    return ((unsigned int)(current - slab));
}

/*
 * Make the dns_rdata_t 'rdata' refer to the slab item
 * beginning at '*current', which is part of a slab of type
 * 'type' and class 'rdclass', and advance '*current' to
 * point to the next item in the slab.
 */
static inline void
rdata_from_slab(unsigned char **current,
          dns_rdataclass_t rdclass, dns_rdatatype_t type,
          dns_rdata_t *rdata)
{
    unsigned char *tcurrent = *current;
    isc_region_t region;

    region.length = *tcurrent++ * 256;
    region.length += *tcurrent++;
    region.base = tcurrent;
    tcurrent += region.length;
    dns_rdata_fromregion(rdata, rdclass, type, &region);
    *current = tcurrent;
}

/*
 * Return true iff 'slab' (slab data of type 'type' and class 'rdclass')
 * contains an rdata identical to 'rdata'.  This does case insensitive
 * comparisons per DNSSEC.
 */
static inline isc_boolean_t
rdata_in_slab(unsigned char *slab, unsigned int reservelen,
          dns_rdataclass_t rdclass, dns_rdatatype_t type,
          dns_rdata_t *rdata)
{
    unsigned int count, i;
    unsigned char *current;
    dns_rdata_t trdata;

    current = slab + reservelen;
    count = *current++ * 256;
    count += *current++;

    dns_rdata_init(&trdata);

    for (i = 0; i < count; i++) {
        rdata_from_slab(&current, rdclass, type, &trdata);
        if (dns_rdata_compare(&trdata, rdata) == 0)
            return (ISC_TRUE);
    }
    return (ISC_FALSE);
}

isc_result_t
dns_rdataslab_merge(unsigned char *oslab, unsigned char *nslab,
            unsigned int reservelen, isc_mem_t *mctx,
            dns_rdataclass_t rdclass, dns_rdatatype_t type,
            isc_boolean_t force, unsigned char **tslabp)
{
    unsigned char *ocurrent, *ostart, *ncurrent, *tstart, *tcurrent;
    unsigned int ocount, ncount, count, olength, tlength, tcount, length;
    isc_region_t nregion;
    dns_rdata_t ordata, nrdata;
    isc_boolean_t added_something = ISC_FALSE;
    unsigned int oadded = 0;
    unsigned int nadded = 0;
    unsigned int nncount = 0;

    /*
     * XXX  Need parameter to allow "delete rdatasets in nslab" merge,
     * or perhaps another merge routine for this purpose.
     */

    REQUIRE(tslabp != NULL && *tslabp == NULL);
    REQUIRE(oslab != NULL && nslab != NULL);

    ocurrent = oslab + reservelen;
    ocount = *ocurrent++ * 256;
    ocount += *ocurrent++;
    ostart = ocurrent;
    ncurrent = nslab + reservelen;
    ncount = *ncurrent++ * 256;
    ncount += *ncurrent++;
    INSIST(ocount > 0 && ncount > 0);

    /*
     * Yes, this is inefficient!
     */

    /*
     * Figure out the length of the old slab's data.
     */
    olength = 0;
    for (count = 0; count < ocount; count++) {
        length = *ocurrent++ * 256;
        length += *ocurrent++;
        olength += length + 2;
        ocurrent += length;
    }

    /*
     * Start figuring out the target length and count.
     */
    tlength = reservelen + 2 + olength;
    tcount = ocount;

    /*
     * Add in the length of rdata in the new slab that aren't in
     * the old slab.
     */
    do {
        nregion.length = *ncurrent++ * 256;
        nregion.length += *ncurrent++;
        nregion.base = ncurrent;
        dns_rdata_fromregion(&nrdata, rdclass, type, &nregion);
        if (!rdata_in_slab(oslab, reservelen, rdclass, type, &nrdata))
        {
            /*
             * This rdata isn't in the old slab.
             */
            tlength += nregion.length + 2;
            tcount++;
            nncount++;
            added_something = ISC_TRUE;
        }
        ncurrent += nregion.length;
        ncount--;
    } while (ncount > 0);
    ncount = nncount;

    if (!added_something && !force)
        return (DNS_R_UNCHANGED);

    /*
     * Copy the reserved area from the new slab.
     */
    tstart = isc_mem_get(mctx, tlength);
    if (tstart == NULL)
        return (ISC_R_NOMEMORY);
    memcpy(tstart, nslab, reservelen);
    tcurrent = tstart + reservelen;

    /*
     * Write the new count.
     */
    *tcurrent++ = (tcount & 0xff00) >> 8;
    *tcurrent++ = (tcount & 0x00ff);

    /*
     * Merge the two slabs.
     */
    ocurrent = ostart;
    INSIST(ocount != 0);
    rdata_from_slab(&ocurrent, rdclass, type, &ordata);

    ncurrent = nslab + reservelen + 2;
    if (ncount > 0) {
        do {
                rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
        } while (rdata_in_slab(oslab, reservelen, rdclass,
                       type, &nrdata));
    }

    while (oadded < ocount || nadded < ncount) {
        isc_boolean_t fromold;
        if (oadded == ocount)
            fromold = ISC_FALSE;
        else if (nadded == ncount)
            fromold = ISC_TRUE;
        else
            fromold = ISC_TF(compare_rdata(&ordata, &nrdata) < 0);
        if (fromold) {
            length = ordata.length;
            *tcurrent++ = (length & 0xff00) >> 8;
            *tcurrent++ = (length & 0x00ff);
            memcpy(tcurrent, ordata.data, length);
            tcurrent += length;
            oadded++;
            if (oadded < ocount) {
                    rdata_from_slab(&ocurrent, rdclass, type,
                        &ordata);
            }
        } else {
            length = nrdata.length;
            *tcurrent++ = (length & 0xff00) >> 8;
            *tcurrent++ = (length & 0x00ff);
            memcpy(tcurrent, nrdata.data, length);
            tcurrent += length;
            nadded++;
            if (nadded < ncount) {
                do {
                        rdata_from_slab(&ncurrent, rdclass,
                            type, &nrdata);
                } while (rdata_in_slab(oslab, reservelen,
                               rdclass, type,
                               &nrdata));
            }
        }
    }

    INSIST(tcurrent == tstart + tlength);

    *tslabp = tstart;

    return (ISC_R_SUCCESS);
}

isc_result_t
dns_rdataslab_subtract(unsigned char *mslab, unsigned char *sslab,
               unsigned int reservelen, isc_mem_t *mctx,
               dns_rdataclass_t rdclass, dns_rdatatype_t type,
               unsigned char **tslabp)
{
    unsigned char *mcurrent, *sstart, *scurrent, *tstart, *tcurrent;
    unsigned int mcount, scount, count, tlength, tcount;
    dns_rdata_t srdata, mrdata;
    isc_boolean_t removed_something = ISC_FALSE;

    REQUIRE(tslabp != NULL && *tslabp == NULL);
    REQUIRE(mslab != NULL && sslab != NULL);

    mcurrent = mslab + reservelen;
    mcount = *mcurrent++ * 256;
    mcount += *mcurrent++;
    scurrent = sslab + reservelen;
    scount = *scurrent++ * 256;
    scount += *scurrent++;
    sstart = scurrent;
    INSIST(mcount > 0 && scount > 0);

    /*
     * Yes, this is inefficient!
     */

    /*
     * Start figuring out the target length and count.
     */
    tlength = reservelen + 2;
    tcount = 0;

    /*
     * Add in the length of rdata in the mslab that aren't in
     * the sslab.
     */
    do {
        unsigned char *mrdatabegin = mcurrent;
        rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
        scurrent = sstart;
        for (count = 0; count < scount; count++) {
            rdata_from_slab(&scurrent, rdclass, type, &srdata);
            if (dns_rdata_compare(&mrdata, &srdata) == 0)
                break;
        }
        if (count == scount) {
            /*
             * This rdata isn't in the sslab, and thus isn't
             * being subtracted.
             */
            tlength += mcurrent - mrdatabegin;
            tcount++;
        } else
            removed_something = ISC_TRUE;
        mcount--;
    } while (mcount > 0);

    /*
     * Don't continue if the new rdataslab would be empty.
     */
    if (tcount == 0)
        return (DNS_R_NXRRSET);

    /*
     * If nothing is going to change, we can stop.
     */
    if (!removed_something)
        return (DNS_R_UNCHANGED);

    /*
     * Copy the reserved area from the mslab.
     */
    tstart = isc_mem_get(mctx, tlength);
    if (tstart == NULL)
        return (ISC_R_NOMEMORY);
    memcpy(tstart, mslab, reservelen);
    tcurrent = tstart + reservelen;

    /*
     * Write the new count.
     */
    *tcurrent++ = (tcount & 0xff00) >> 8;
    *tcurrent++ = (tcount & 0x00ff);

    /*
     * Copy the parts of mslab not in sslab.
     */
    mcurrent = mslab + reservelen;
    mcount = *mcurrent++ * 256;
    mcount += *mcurrent++;
    do {
        unsigned char *mrdatabegin = mcurrent;
        rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
        scurrent = sstart;
        for (count = 0; count < scount; count++) {
            rdata_from_slab(&scurrent, rdclass, type, &srdata);
            if (dns_rdata_compare(&mrdata, &srdata) == 0)
                break;
        }
        if (count == scount) {
            /*
             * This rdata isn't in the sslab, and thus should be
             * copied to the tslab.
             */
            unsigned int length = mcurrent - mrdatabegin;
            memcpy(tcurrent, mrdatabegin, length);
            tcurrent += length;
        }
        mcount--;
    } while (mcount > 0);

    INSIST(tcurrent == tstart + tlength);

    *tslabp = tstart;

    return (ISC_R_SUCCESS);
}

isc_boolean_t
dns_rdataslab_equal(unsigned char *slab1, unsigned char *slab2,
            unsigned int reservelen)
{
    unsigned char *current1, *current2;
    unsigned int count1, count2;
    unsigned int length1, length2;

    current1 = slab1 + reservelen;
    count1 = *current1++ * 256;
    count1 += *current1++;

    current2 = slab2 + reservelen;
    count2 = *current2++ * 256;
    count2 += *current2++;

    if (count1 != count2)
        return (ISC_FALSE);

    while (count1 > 0) {
        length1 = *current1++ * 256;
        length1 += *current1++;

        length2 = *current2++ * 256;
        length2 += *current2++;

        if (length1 != length2 ||
            memcmp(current1, current2, length1) != 0)
            return (ISC_FALSE);

        current1 += length1;
        current2 += length1;

        count1--;
    }
    return (ISC_TRUE);
}