message.c

非常好的dns解析软件

	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);
	REQUIRE(msg->cursors[section] != NULL);

	*name = msg->cursors[section];
}

isc_result_t
dns_message_findname(dns_message_t *msg, dns_section_t section,
		     dns_name_t *target, dns_rdatatype_t type,
		     dns_rdatatype_t covers, dns_name_t **name,
		     dns_rdataset_t **rdataset)
{
	dns_name_t *foundname;
	isc_result_t result;

	/*
	 * XXX These requirements are probably too intensive, especially
	 * where things can be NULL, but as they are they ensure that if
	 * something is NON-NULL, indicating that the caller expects it
	 * to be filled in, that we can in fact fill it in.
	 */
	REQUIRE(msg != NULL);
	REQUIRE(VALID_SECTION(section));
	REQUIRE(target != NULL);
	if (name != NULL)
		REQUIRE(*name == NULL);
	if (type == dns_rdatatype_any) {
		REQUIRE(rdataset == NULL);
	} else {
		if (rdataset != NULL)
			REQUIRE(*rdataset == NULL);
	}

	result = findname(&foundname, target,
			  &msg->sections[section]);

	if (result == ISC_R_NOTFOUND)
		return (DNS_R_NXDOMAIN);
	else if (result != ISC_R_SUCCESS)
		return (result);

	if (name != NULL)
		*name = foundname;

	/*
	 * And now look for the type.
	 */
	if (type == dns_rdatatype_any)
		return (ISC_R_SUCCESS);

	result = dns_message_findtype(foundname, type, covers, rdataset);
	if (result == ISC_R_NOTFOUND)
		return (DNS_R_NXRRSET);

	return (result);
}

void
dns_message_movename(dns_message_t *msg, dns_name_t *name,
		     dns_section_t fromsection,
		     dns_section_t tosection)
{
	REQUIRE(msg != NULL);
	REQUIRE(msg->from_to_wire == DNS_MESSAGE_INTENTRENDER);
	REQUIRE(name != NULL);
	REQUIRE(VALID_NAMED_SECTION(fromsection));
	REQUIRE(VALID_NAMED_SECTION(tosection));

	/*
	 * Unlink the name from the old section
	 */
	ISC_LIST_UNLINK(msg->sections[fromsection], name, link);
	ISC_LIST_APPEND(msg->sections[tosection], name, link);
}

void
dns_message_addname(dns_message_t *msg, dns_name_t *name,
		    dns_section_t section)
{
	REQUIRE(msg != NULL);
	REQUIRE(msg->from_to_wire == DNS_MESSAGE_INTENTRENDER);
	REQUIRE(name != NULL);
	REQUIRE(VALID_NAMED_SECTION(section));

	ISC_LIST_APPEND(msg->sections[section], name, link);
}

void
dns_message_removename(dns_message_t *msg, dns_name_t *name,
		       dns_section_t section)
{
	REQUIRE(msg != NULL);
	REQUIRE(msg->from_to_wire == DNS_MESSAGE_INTENTRENDER);
	REQUIRE(name != NULL);
	REQUIRE(VALID_NAMED_SECTION(section));

	ISC_LIST_UNLINK(msg->sections[section], name, link);
}

isc_result_t
dns_message_gettempname(dns_message_t *msg, dns_name_t **item) {
	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(item != NULL && *item == NULL);

	*item = isc_mempool_get(msg->namepool);
	if (*item == NULL)
		return (ISC_R_NOMEMORY);
	dns_name_init(*item, NULL);

	return (ISC_R_SUCCESS);
}

isc_result_t
dns_message_gettempoffsets(dns_message_t *msg, dns_offsets_t **item) {
	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(item != NULL && *item == NULL);

	*item = newoffsets(msg);
	if (*item == NULL)
		return (ISC_R_NOMEMORY);

	return (ISC_R_SUCCESS);
}

isc_result_t
dns_message_gettemprdata(dns_message_t *msg, dns_rdata_t **item) {
	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(item != NULL && *item == NULL);

	*item = newrdata(msg);
	if (*item == NULL)
		return (ISC_R_NOMEMORY);

	return (ISC_R_SUCCESS);
}

isc_result_t
dns_message_gettemprdataset(dns_message_t *msg, dns_rdataset_t **item) {
	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(item != NULL && *item == NULL);

	*item = isc_mempool_get(msg->rdspool);
	if (*item == NULL)
		return (ISC_R_NOMEMORY);

	dns_rdataset_init(*item);

	return (ISC_R_SUCCESS);
}

isc_result_t
dns_message_gettemprdatalist(dns_message_t *msg, dns_rdatalist_t **item) {
	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(item != NULL && *item == NULL);

	*item = newrdatalist(msg);
	if (*item == NULL)
		return (ISC_R_NOMEMORY);

	return (ISC_R_SUCCESS);
}

void
dns_message_puttempname(dns_message_t *msg, dns_name_t **item) {
	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(item != NULL && *item != NULL);

	if (dns_name_dynamic(*item))
		dns_name_free(*item, msg->mctx);
	isc_mempool_put(msg->namepool, *item);
	*item = NULL;
}

void
dns_message_puttemprdata(dns_message_t *msg, dns_rdata_t **item) {
	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(item != NULL && *item != NULL);

	releaserdata(msg, *item);
	*item = NULL;
}

void
dns_message_puttemprdataset(dns_message_t *msg, dns_rdataset_t **item) {
	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(item != NULL && *item != NULL);

	REQUIRE(!dns_rdataset_isassociated(*item));
	isc_mempool_put(msg->rdspool, *item);
	*item = NULL;
}

void
dns_message_puttemprdatalist(dns_message_t *msg, dns_rdatalist_t **item) {
	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(item != NULL && *item != NULL);

	releaserdatalist(msg, *item);
	*item = NULL;
}

isc_result_t
dns_message_peekheader(isc_buffer_t *source, dns_messageid_t *idp,
		       unsigned int *flagsp)
{
	isc_region_t r;
	isc_buffer_t buffer;
	dns_messageid_t id;
	unsigned int flags;

	REQUIRE(source != NULL);

	buffer = *source;

	isc_buffer_remainingregion(&buffer, &r);
	if (r.length < DNS_MESSAGE_HEADERLEN)
		return (ISC_R_UNEXPECTEDEND);

	id = isc_buffer_getuint16(&buffer);
	flags = isc_buffer_getuint16(&buffer);
	flags &= DNS_MESSAGE_FLAG_MASK;

	if (flagsp != NULL)
		*flagsp = flags;
	if (idp != NULL)
		*idp = id;

	return (ISC_R_SUCCESS);
}

isc_result_t
dns_message_reply(dns_message_t *msg, isc_boolean_t want_question_section) {
	unsigned int first_section;
	isc_result_t result;

	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE((msg->flags & DNS_MESSAGEFLAG_QR) == 0);

	if (!msg->header_ok)
		return (DNS_R_FORMERR);
	if (msg->opcode != dns_opcode_query &&
	    msg->opcode != dns_opcode_notify)
		want_question_section = ISC_FALSE;
	if (want_question_section) {
		if (!msg->question_ok)
			return (DNS_R_FORMERR);
		first_section = DNS_SECTION_ANSWER;
	} else
		first_section = DNS_SECTION_QUESTION;
	msg->from_to_wire = DNS_MESSAGE_INTENTRENDER;
	msgresetnames(msg, first_section);
	msgresetopt(msg);
	msgresetsigs(msg, ISC_TRUE);
	msginitprivate(msg);
	/*
	 * We now clear most flags and then set QR, ensuring that the
	 * reply's flags will be in a reasonable state.
	 */
	msg->flags &= DNS_MESSAGE_REPLYPRESERVE;
	msg->flags |= DNS_MESSAGEFLAG_QR;

	/*
	 * This saves the query TSIG status, if the query was signed, and
	 * reserves space in the reply for the TSIG.
	 */
	if (msg->tsigkey != NULL) {
		unsigned int otherlen = 0;
		msg->querytsigstatus = msg->tsigstatus;
		msg->tsigstatus = dns_rcode_noerror;
		if (msg->querytsigstatus == dns_tsigerror_badtime)
			otherlen = 6;
		msg->sig_reserved = spacefortsig(msg->tsigkey, otherlen);
		result = dns_message_renderreserve(msg, msg->sig_reserved);
		if (result != ISC_R_SUCCESS) {
			msg->sig_reserved = 0;
			return (result);
		}
	}
	if (msg->saved.base != NULL) {
		msg->query.base = msg->saved.base;
		msg->query.length = msg->saved.length;
		msg->free_query = msg->free_saved;
		msg->saved.base = NULL;
		msg->saved.length = 0;
		msg->free_saved = 0;
	}

	return (ISC_R_SUCCESS);
}

dns_rdataset_t *
dns_message_getopt(dns_message_t *msg) {

	/*
	 * Get the OPT record for 'msg'.
	 */

	REQUIRE(DNS_MESSAGE_VALID(msg));

	return (msg->opt);
}

isc_result_t
dns_message_setopt(dns_message_t *msg, dns_rdataset_t *opt) {
	isc_result_t result;
	dns_rdata_t rdata = DNS_RDATA_INIT;

	/*
	 * Set the OPT record for 'msg'.
	 */

	/*
	 * The space required for an OPT record is:
	 *
	 *	1 byte for the name
	 *	2 bytes for the type
	 *	2 bytes for the class
	 *	4 bytes for the ttl
	 *	2 bytes for the rdata length
	 * ---------------------------------
	 *     11 bytes
	 *
	 * plus the length of the rdata.
	 */

	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(opt->type == dns_rdatatype_opt);
	REQUIRE(msg->from_to_wire == DNS_MESSAGE_INTENTRENDER);
	REQUIRE(msg->state == DNS_SECTION_ANY);

	msgresetopt(msg);

	result = dns_rdataset_first(opt);
	if (result != ISC_R_SUCCESS)
		goto cleanup;
	dns_rdataset_current(opt, &rdata);
	msg->opt_reserved = 11 + rdata.length;
	result = dns_message_renderreserve(msg, msg->opt_reserved);
	if (result != ISC_R_SUCCESS) {
		msg->opt_reserved = 0;
		goto cleanup;
	}

	msg->opt = opt;

	return (ISC_R_SUCCESS);

 cleanup:
	dns_message_puttemprdataset(msg, &opt);
	return (result);

}

dns_rdataset_t *
dns_message_gettsig(dns_message_t *msg, dns_name_t **owner) {

	/*
	 * Get the TSIG record and owner for 'msg'.
	 */

	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(owner == NULL || *owner == NULL);

	if (owner != NULL)
		*owner = msg->tsigname;
	return (msg->tsig);
}

isc_result_t
dns_message_settsigkey(dns_message_t *msg, dns_tsigkey_t *key) {
	isc_result_t result;

	/*
	 * Set the TSIG key for 'msg'
	 */

	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(msg->state == DNS_SECTION_ANY);

	if (key == NULL && msg->tsigkey != NULL) {
		if (msg->sig_reserved != 0) {
			dns_message_renderrelease(msg, msg->sig_reserved);
			msg->sig_reserved = 0;
		}
		dns_tsigkey_detach(&msg->tsigkey);
	}
	if (key != NULL) {
		REQUIRE(msg->tsigkey == NULL && msg->sig0key == NULL);
		dns_tsigkey_attach(key, &msg->tsigkey);
		if (msg->from_to_wire == DNS_MESSAGE_INTENTRENDER) {
			msg->sig_reserved = spacefortsig(msg->tsigkey, 0);
			result = dns_message_renderreserve(msg,
							   msg->sig_reserved);
			if (result != ISC_R_SUCCESS) {
				dns_tsigkey_detach(&msg->tsigkey);
				msg->sig_reserved = 0;
				return (result);
			}
		}
	}
	return (ISC_R_SUCCESS);
}

dns_tsigkey_t *
dns_message_gettsigkey(dns_message_t *msg) {

	/*
	 * Get the TSIG key for 'msg'
	 */

	REQUIRE(DNS_MESSAGE_VALID(msg));

	return (msg->tsigkey);
}

isc_result_t
dns_message_setquerytsig(dns_message_t *msg, isc_buffer_t *querytsig) {
	dns_rdata_t *rdata = NULL;
	dns_rdatalist_t *list = NULL;
	dns_rdataset_t *set = NULL;
	isc_buffer_t *buf = NULL;
	isc_region_t r;
	isc_result_t result;

	REQUIRE(DNS_MESSAGE_VALID(msg));
	REQUIRE(msg->querytsig == NULL);

	if (querytsig == NULL)
		return (ISC_R_SUCCESS);

	result = dns_message_gettemprdata(msg, &rdata);
	if (result != ISC_R_SUCCESS)
		goto cleanup;

	result = dns_message_gettemprdatalist(msg, &list);
	if (result != ISC_R_SUCCESS)
		goto cleanup;
	result = dns_message_gettemprdataset(msg, &set);
	if (result != ISC_R_SUCCESS)
		goto cleanup;

	isc_buffer_usedregion(querytsig, &r);
	result = isc_buffer_allocate(m