message.c

bind 9.3结合mysql数据库

			      DNS_LOGMODULE_MESSAGE, ISC_LOG_DEBUG(3),
			      "message has %u byte(s) of trailing garbage",
			      r.length);
	}

 truncated:
	if ((options & DNS_MESSAGEPARSE_CLONEBUFFER) == 0)
		isc_buffer_usedregion(&origsource, &msg->saved);
	else {
		msg->saved.length = isc_buffer_usedlength(&origsource);
		msg->saved.base = isc_mem_get(msg->mctx, msg->saved.length);
		if (msg->saved.base == NULL)
			return (ISC_R_NOMEMORY);
		memcpy(msg->saved.base, isc_buffer_base(&origsource),
		       msg->saved.length);
		msg->free_saved = 1;
	}

	if (ret == ISC_R_UNEXPECTEDEND && ignore_tc)
		return (DNS_R_RECOVERABLE);
	if (seen_problem == ISC_TRUE)
		return (DNS_R_RECOVERABLE);
	return (ISC_R_SUCCESS);
}

isc_result_t
dns_message_renderbegin(dns_message_t *msg, dns_compress_t *cctx,
			isc_buffer_t *buffer)
{
	isc_region_t r;

	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(buffer != NULL);
	REQUIRE(msg->buffer == NULL);
	REQUIRE(msg->from_to_wire == DNS_MESSAGE_INTENTRENDER);

	msg->cctx = cctx;

	/*
	 * Erase the contents of this buffer.
	 */
	isc_buffer_clear(buffer);

	/*
	 * Make certain there is enough for at least the header in this
	 * buffer.
	 */
	isc_buffer_availableregion(buffer, &r);
	if (r.length < DNS_MESSAGE_HEADERLEN)
		return (ISC_R_NOSPACE);

	if (r.length < msg->reserved)
		return (ISC_R_NOSPACE);

	/*
	 * Reserve enough space for the header in this buffer.
	 */
	isc_buffer_add(buffer, DNS_MESSAGE_HEADERLEN);

	msg->buffer = buffer;

	return (ISC_R_SUCCESS);
}

isc_result_t
dns_message_renderchangebuffer(dns_message_t *msg, isc_buffer_t *buffer) {
	isc_region_t r, rn;

	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(buffer != NULL);
	REQUIRE(msg->buffer != NULL);

	/*
	 * Ensure that the new buffer is empty, and has enough space to
	 * hold the current contents.
	 */
	isc_buffer_clear(buffer);

	isc_buffer_availableregion(buffer, &rn);
	isc_buffer_usedregion(msg->buffer, &r);
	REQUIRE(rn.length > r.length);

	/*
	 * Copy the contents from the old to the new buffer.
	 */
	isc_buffer_add(buffer, r.length);
	memcpy(rn.base, r.base, r.length);

	msg->buffer = buffer;

	return (ISC_R_SUCCESS);
}

void
dns_message_renderrelease(dns_message_t *msg, unsigned int space) {
	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(space <= msg->reserved);

	msg->reserved -= space;
}

isc_result_t
dns_message_renderreserve(dns_message_t *msg, unsigned int space) {
	isc_region_t r;

	REQUIRE(DNS_MESSAGE_VALID(msg));

	if (msg->buffer != NULL) {
		isc_buffer_availableregion(msg->buffer, &r);
		if (r.length < (space + msg->reserved))
			return (ISC_R_NOSPACE);
	}

	msg->reserved += space;

	return (ISC_R_SUCCESS);
}

static inline isc_boolean_t
wrong_priority(dns_rdataset_t *rds, int pass, dns_rdatatype_t preferred_glue) {
	int pass_needed;

	/*
	 * If we are not rendering class IN, this ordering is bogus.
	 */
	if (rds->rdclass != dns_rdataclass_in)
		return (ISC_FALSE);

	switch (rds->type) {
	case dns_rdatatype_a:
	case dns_rdatatype_aaaa:
		if (preferred_glue == rds->type)
			pass_needed = 4;
		else
			pass_needed = 3;
		break;
	case dns_rdatatype_rrsig:
	case dns_rdatatype_dnskey:
		pass_needed = 2;
		break;
	default:
		pass_needed = 1;
	}

	if (pass_needed >= pass)
		return (ISC_FALSE);

	return (ISC_TRUE);
}

isc_result_t
dns_message_rendersection(dns_message_t *msg, dns_section_t sectionid,
			  unsigned int options)
{
	dns_namelist_t *section;
	dns_name_t *name, *next_name;
	dns_rdataset_t *rdataset, *next_rdataset;
	unsigned int count, total;
	isc_result_t result;
	isc_buffer_t st; /* for rollbacks */
	int pass;
	isc_boolean_t partial = ISC_FALSE;
	unsigned int rd_options;
	dns_rdatatype_t preferred_glue = 0;

	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(msg->buffer != NULL);
	REQUIRE(VALID_NAMED_SECTION(sectionid));

	section = &msg->sections[sectionid];

	if ((sectionid == DNS_SECTION_ADDITIONAL)
	    && (options & DNS_MESSAGERENDER_ORDERED) == 0) {
		if ((options & DNS_MESSAGERENDER_PREFER_A) != 0) {
			preferred_glue = dns_rdatatype_a;
			pass = 4;
		} else if ((options & DNS_MESSAGERENDER_PREFER_AAAA) != 0) {
			preferred_glue = dns_rdatatype_aaaa;
			pass = 4;
		} else
			pass = 3;
	} else
		pass = 1;

	if ((options & DNS_MESSAGERENDER_OMITDNSSEC) == 0)
		rd_options = 0;
	else
		rd_options = DNS_RDATASETTOWIRE_OMITDNSSEC;

	/*
	 * Shrink the space in the buffer by the reserved amount.
	 */
	msg->buffer->length -= msg->reserved;

	total = 0;
	if (msg->reserved == 0 && (options & DNS_MESSAGERENDER_PARTIAL) != 0)
		partial = ISC_TRUE;

	do {
		name = ISC_LIST_HEAD(*section);
		if (name == NULL) {
			msg->buffer->length += msg->reserved;
			msg->counts[sectionid] += total;
			return (ISC_R_SUCCESS);
		}

		while (name != NULL) {
			next_name = ISC_LIST_NEXT(name, link);

			rdataset = ISC_LIST_HEAD(name->list);
			while (rdataset != NULL) {
				next_rdataset = ISC_LIST_NEXT(rdataset, link);

				if ((rdataset->attributes &
				     DNS_RDATASETATTR_RENDERED) != 0)
					goto next;

				if (((options & DNS_MESSAGERENDER_ORDERED)
				     == 0)
				    && (sectionid == DNS_SECTION_ADDITIONAL)
				    && wrong_priority(rdataset, pass,
						      preferred_glue))
					goto next;

				st = *(msg->buffer);

				count = 0;
				if (partial)
					result = dns_rdataset_towirepartial(
							  rdataset,
							  name,
							  msg->cctx,
							  msg->buffer,
							  msg->order,
							  msg->order_arg,
							  rd_options,
							  &count,
							  NULL);
				else
					result = dns_rdataset_towiresorted(
							  rdataset,
							  name,
							  msg->cctx,
							  msg->buffer,
							  msg->order,
							  msg->order_arg,
							  rd_options,
							  &count);

				total += count;

				/*
				 * If out of space, record stats on what we
				 * rendered so far, and return that status.
				 *
				 * XXXMLG Need to change this when
				 * dns_rdataset_towire() can render partial
				 * sets starting at some arbitary point in the
				 * set.  This will include setting a bit in the
				 * rdataset to indicate that a partial
				 * rendering was done, and some state saved
				 * somewhere (probably in the message struct)
				 * to indicate where to continue from.
				 */
				if (partial && result == ISC_R_NOSPACE) {
					msg->buffer->length += msg->reserved;
					msg->counts[sectionid] += total;
					return (result);
				}
				if (result != ISC_R_SUCCESS) {
					INSIST(st.used < 65536);
					dns_compress_rollback(msg->cctx,
							(isc_uint16_t)st.used);
					*(msg->buffer) = st;  /* rollback */
					msg->buffer->length += msg->reserved;
					msg->counts[sectionid] += total;
					return (result);
				}

				/*
				 * If we have rendered non-validated data,
				 * ensure that the AD bit is not set.
				 */
				if (rdataset->trust != dns_trust_secure &&
				    (sectionid == DNS_SECTION_ANSWER ||
				     sectionid == DNS_SECTION_AUTHORITY))
					msg->flags &= ~DNS_MESSAGEFLAG_AD;

				rdataset->attributes |=
					DNS_RDATASETATTR_RENDERED;

			next:
				rdataset = next_rdataset;
			}

			name = next_name;
		}
	} while (--pass != 0);

	msg->buffer->length += msg->reserved;
	msg->counts[sectionid] += total;

	return (ISC_R_SUCCESS);
}

void
dns_message_renderheader(dns_message_t *msg, isc_buffer_t *target) {
	isc_uint16_t tmp;
	isc_region_t r;

	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(target != NULL);

	isc_buffer_availableregion(target, &r);
	REQUIRE(r.length >= DNS_MESSAGE_HEADERLEN);

	isc_buffer_putuint16(target, msg->id);

	tmp = ((msg->opcode << DNS_MESSAGE_OPCODE_SHIFT)
	       & DNS_MESSAGE_OPCODE_MASK);
	tmp |= (msg->rcode & DNS_MESSAGE_RCODE_MASK);
	tmp |= (msg->flags & DNS_MESSAGE_FLAG_MASK);

	INSIST(msg->counts[DNS_SECTION_QUESTION]  < 65536 &&
	       msg->counts[DNS_SECTION_ANSWER]    < 65536 &&
	       msg->counts[DNS_SECTION_AUTHORITY] < 65536 &&
	       msg->counts[DNS_SECTION_ADDITIONAL] < 65536);

	isc_buffer_putuint16(target, tmp);
	isc_buffer_putuint16(target,
			    (isc_uint16_t)msg->counts[DNS_SECTION_QUESTION]);
	isc_buffer_putuint16(target,
			    (isc_uint16_t)msg->counts[DNS_SECTION_ANSWER]);
	isc_buffer_putuint16(target,
			    (isc_uint16_t)msg->counts[DNS_SECTION_AUTHORITY]);
	isc_buffer_putuint16(target,
			    (isc_uint16_t)msg->counts[DNS_SECTION_ADDITIONAL]);
}

isc_result_t
dns_message_renderend(dns_message_t *msg) {
	isc_buffer_t tmpbuf;
	isc_region_t r;
	int result;
	unsigned int count;

	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(msg->buffer != NULL);

	if ((msg->rcode & ~DNS_MESSAGE_RCODE_MASK) != 0 && msg->opt == NULL) {
		/*
		 * We have an extended rcode but are not using EDNS.
		 */
		return (DNS_R_FORMERR);
	}

	/*
	 * If we've got an OPT record, render it.
	 */
	if (msg->opt != NULL) {
		dns_message_renderrelease(msg, msg->opt_reserved);
		msg->opt_reserved = 0;
		/*
		 * Set the extended rcode.
		 */
		msg->opt->ttl &= ~DNS_MESSAGE_EDNSRCODE_MASK;
		msg->opt->ttl |= ((msg->rcode << 20) &
				  DNS_MESSAGE_EDNSRCODE_MASK);
		/*
		 * Render.
		 */
		count = 0;
		result = dns_rdataset_towire(msg->opt, dns_rootname,
					     msg->cctx, msg->buffer, 0,
					     &count);
		msg->counts[DNS_SECTION_ADDITIONAL] += count;
		if (result != ISC_R_SUCCESS)
			return (result);
	}

	/*
	 * If we're adding a TSIG or SIG(0) to a truncated message,
	 * clear all rdatasets from the message except for the question
	 * before adding the TSIG or SIG(0).  If the question doesn't fit,
	 * don't include it.
	 */
	if ((msg->tsigkey != NULL || msg->sig0key != NULL) &&
	    (msg->flags & DNS_MESSAGEFLAG_TC) != 0)
	{
		isc_buffer_t *buf;

		msgresetnames(msg, DNS_SECTION_ANSWER);
		buf = msg->buffer;
		dns_message_renderreset(msg);
		msg->buffer = buf;
		isc_buffer_clear(msg->buffer);
		isc_buffer_add(msg->buffer, DNS_MESSAGE_HEADERLEN);
		dns_compress_rollback(msg->cctx, 0);
		result = dns_message_rendersection(msg, DNS_SECTION_QUESTION,
						   0);
		if (result != ISC_R_SUCCESS && result != ISC_R_NOSPACE)
			return (result);
	}

	/*
	 * If we're adding a TSIG record, generate and render it.
	 */
	if (msg->tsigkey != NULL) {
		dns_message_renderrelease(msg, msg->sig_reserved);
		msg->sig_reserved = 0;
		result = dns_tsig_sign(msg);
		if (result != ISC_R_SUCCESS)
			return (result);
		count = 0;
		result = dns_rdataset_towire(msg->tsig, msg->tsigname,
					     msg->cctx, msg->buffer, 0,
					     &count);
		msg->counts[DNS_SECTION_ADDITIONAL] += count;
		if (result != ISC_R_SUCCESS)
			return (result);
	}

	/*
	 * If we're adding a SIG(0) record, generate and render it.
	 */
	if (msg->sig0key != NULL) {
		dns_message_renderrelease(msg, msg->sig_reserved);
		msg->sig_reserved = 0;
		result = dns_dnssec_signmessage(msg, msg->sig0key);
		if (result != ISC_R_SUCCESS)
			return (result);
		count = 0;
		/*
		 * Note: dns_rootname is used here, not msg->sig0name, since
		 * the owner name of a SIG(0) is irrelevant, and will not
		 * be set in a message being rendered.
		 */
		result = dns_rdataset_towire(msg->sig0, dns_rootname,
					     msg->cctx, msg->buffer, 0,
					     &count);
		msg->counts[DNS_SECTION_ADDITIONAL] += count;
		if (result != ISC_R_SUCCESS)
			return (result);
	}

	isc_buffer_usedregion(msg->buffer, &r);
	isc_buffer_init(&tmpbuf, r.base, r.length);

	dns_message_renderheader(msg, &tmpbuf);

	msg->buffer = NULL;  /* forget about this buffer only on success XXX */

	return (ISC_R_SUCCESS);
}

void
dns_message_renderreset(dns_message_t *msg) {
	unsigned int i;
	dns_name_t *name;
	dns_rdataset_t *rds;

	/*
	 * Reset the message so that it may be rendered again.
	 */

	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(msg->from_to_wire == DNS_MESSAGE_INTENTRENDER);

	msg->buffer = NULL;

	for (i = 0; i < DNS_SECTION_MAX; i++) {
		msg->cursors[i] = NULL;
		msg->counts[i] = 0;
		for (name = ISC_LIST_HEAD(msg->sections[i]);
		     name != NULL;
		     name = ISC_LIST_NEXT(name, link)) {
			for (rds = ISC_LIST_HEAD(name->list);
			     rds != NULL;
			     rds = ISC_LIST_NEXT(rds, link)) {
				rds->attributes &= ~DNS_RDATASETATTR_RENDERED;
			}
		}
	}
	if (msg->tsigname != NULL)
		dns_message_puttempname(msg, &msg->tsigname);
	if (msg->tsig != NULL) {
		dns_rdataset_disassociate(msg->tsig);
		dns_message_puttemprdataset(msg, &msg->tsig);
	}
	if (msg->sig0 != NULL) {
		dns_rdataset_disassociate(msg->sig0);
		dns_message_puttemprdataset(msg, &msg->sig0);
	}
}

isc_result_t
dns_message_firstname(dns_message_t *msg, dns_section_t section) {
	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(VALID_NAMED_SECTION(section));

	msg->cursors[section] = ISC_LIST_HEAD(msg->sections[section]);

	if (msg->cursors[section] == NULL)
		return (ISC_R_NOMORE);

	return (ISC_R_SUCCESS);
}

isc_result_t
dns_message_nextname(dns_message_t *msg, dns_section_t section) {
	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(VALID_NAMED_SECTION(section));
	REQUIRE(msg->cursors[section] != NULL);

	msg->cursors[section] = ISC_LIST_NEXT(msg->cursors[section], link);

	if (msg->cursors[section] == NULL)
		return (ISC_R_NOMORE);

	return (ISC_R_SUCCESS);
}

void
dns_message_currentname(dns_message_t *msg, dns_section_t section,
			dns_name_t **name)
{
	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(VALID_NAMED_SECTION(section));
	REQUIRE(name != NULL && *name == NULL);