rdataslab.c

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	 * 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_init(&nrdata);
		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 (((flags & DNS_RDATASLAB_EXACT) != 0) &&
	    (tcount != ncount + ocount))
		return (DNS_R_NOTEXACT);

	if (!added_something && (flags & DNS_RDATASLAB_FORCE) == 0)
		return (DNS_R_UNCHANGED);

	/*
	 * Ensure that singleton types are actually singletons.
	 */
	if (tcount > 1 && dns_rdatatype_issingleton(type)) {
		/*
		 * We have a singleton type, but there's more than one
		 * RR in the rdataset.
		 */
		return (DNS_R_SINGLETON);
	}

	/*
	 * 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 {
			dns_rdata_reset(&nrdata);
       			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) {
				dns_rdata_reset(&ordata);
       				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 {
					dns_rdata_reset(&nrdata);
       					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 int flags, unsigned char **tslabp)
{
	unsigned char *mcurrent, *sstart, *scurrent, *tstart, *tcurrent;
	unsigned int mcount, scount, rcount ,count, tlength, tcount;
	dns_rdata_t srdata = DNS_RDATA_INIT;
	dns_rdata_t mrdata = DNS_RDATA_INIT;

	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;
	rcount = 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++) {
			dns_rdata_reset(&srdata);
			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
			rcount++;
		mcount--;
		dns_rdata_reset(&mrdata);
	} while (mcount > 0);

	/*
	 * Check that all the records originally existed.  The numeric
 	 * check only works as rdataslabs do not contain duplicates.
	 */
	if (((flags & DNS_RDATASLAB_EXACT) != 0) && (rcount != scount))
		return (DNS_R_NOTEXACT);

	/*
	 * 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 (rcount == 0)
		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++) {
			dns_rdata_reset(&srdata);
			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;
		}
		dns_rdata_reset(&mrdata);
		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);
}

isc_boolean_t
dns_rdataslab_equalx(unsigned char *slab1, unsigned char *slab2,
		     unsigned int reservelen, dns_rdataclass_t rdclass,
		     dns_rdatatype_t type)
{
	unsigned char *current1, *current2;
	unsigned int count1, count2;
	dns_rdata_t rdata1 = DNS_RDATA_INIT;
	dns_rdata_t rdata2 = DNS_RDATA_INIT;

	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) {
		rdata_from_slab(&current1, rdclass, type, &rdata1);
		rdata_from_slab(&current2, rdclass, type, &rdata2);
		if (dns_rdata_compare(&rdata1, &rdata2) != 0)
			return (ISC_FALSE);
		dns_rdata_reset(&rdata1);
		dns_rdata_reset(&rdata2);
	}
	return (ISC_TRUE);
}