bind/lib/ns/notify.c

/*
 * Copyright (C) 2017  Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

#include <config.h>

#include <isc/log.h>
#include <isc/print.h>

#include <dns/message.h>
#include <dns/rdataset.h>
#include <dns/result.h>
#include <dns/tsig.h>
#include <dns/view.h>
#include <dns/zone.h>
#include <dns/zt.h>

#include <ns/log.h>
#include <ns/notify.h>
#include <ns/types.h>

/*! \file
 * \brief
 * This module implements notify as in RFC1996.
 */

static void
notify_log(ns_client_t *client, int level, const char *fmt, ...) {
	va_list ap;

	va_start(ap, fmt);
	ns_client_logv(client, DNS_LOGCATEGORY_NOTIFY, NS_LOGMODULE_NOTIFY,
		       level, fmt, ap);
	va_end(ap);
}

static void
respond(ns_client_t *client, isc_result_t result) {
	dns_rcode_t rcode;
	dns_message_t *message;
	isc_result_t msg_result;

	message = client->message;
	rcode = dns_result_torcode(result);

	msg_result = dns_message_reply(message, ISC_TRUE);
	if (msg_result != ISC_R_SUCCESS)
		msg_result = dns_message_reply(message, ISC_FALSE);
	if (msg_result != ISC_R_SUCCESS) {
		ns_client_next(client, msg_result);
		return;
	}
	message->rcode = rcode;
	if (rcode == dns_rcode_noerror)
		message->flags |= DNS_MESSAGEFLAG_AA;
	else
		message->flags &= ~DNS_MESSAGEFLAG_AA;
	ns_client_send(client);
}

void
ns_notify_start(ns_client_t *client) {
	dns_message_t *request = client->message;
	isc_result_t result;
	dns_name_t *zonename;
	dns_rdataset_t *zone_rdataset;
	dns_zone_t *zone = NULL;
	char namebuf[DNS_NAME_FORMATSIZE];
	char tsigbuf[DNS_NAME_FORMATSIZE + sizeof(": TSIG ''")];
	dns_tsigkey_t *tsigkey;

	/*
	 * Interpret the question section.
	 */
	result = dns_message_firstname(request, DNS_SECTION_QUESTION);
	if (result != ISC_R_SUCCESS) {
		notify_log(client, ISC_LOG_NOTICE,
			   "notify question section empty");
		goto formerr;
	}

	/*
	 * The question section must contain exactly one question.
	 */
	zonename = NULL;
	dns_message_currentname(request, DNS_SECTION_QUESTION, &zonename);
	zone_rdataset = ISC_LIST_HEAD(zonename->list);
	if (ISC_LIST_NEXT(zone_rdataset, link) != NULL) {
		notify_log(client, ISC_LOG_NOTICE,
			   "notify question section contains multiple RRs");
		goto formerr;
	}

	/* The zone section must have exactly one name. */
	result = dns_message_nextname(request, DNS_SECTION_ZONE);
	if (result != ISC_R_NOMORE) {
		notify_log(client, ISC_LOG_NOTICE,
			   "notify question section contains multiple RRs");
		goto formerr;
	}

	/* The one rdataset must be an SOA. */
	if (zone_rdataset->type != dns_rdatatype_soa) {
		notify_log(client, ISC_LOG_NOTICE,
			   "notify question section contains no SOA");
		goto formerr;
	}

	tsigkey = dns_message_gettsigkey(request);
	if (tsigkey != NULL) {
		dns_name_format(&tsigkey->name, namebuf, sizeof(namebuf));

		if (tsigkey->generated) {
			char cnamebuf[DNS_NAME_FORMATSIZE];
			dns_name_format(tsigkey->creator, cnamebuf,
					sizeof(cnamebuf));
			snprintf(tsigbuf, sizeof(tsigbuf), ": TSIG '%s' (%s)",
				 namebuf, cnamebuf);
		} else {
			snprintf(tsigbuf, sizeof(tsigbuf), ": TSIG '%s'",
				 namebuf);
		}
	} else
		tsigbuf[0] = '\0';
	dns_name_format(zonename, namebuf, sizeof(namebuf));
	result = dns_zt_find(client->view->zonetable, zonename, 0, NULL,
			     &zone);
	if (result != ISC_R_SUCCESS)
		goto notauth;

	switch (dns_zone_gettype(zone)) {
	case dns_zone_master:
	case dns_zone_slave:
	case dns_zone_stub:	/* Allow dialup passive to work. */
		notify_log(client, ISC_LOG_INFO,
			   "received notify for zone '%s'%s", namebuf, tsigbuf);
		respond(client, dns_zone_notifyreceive(zone,
			ns_client_getsockaddr(client), request));
		break;
	default:
		goto notauth;
	}
	dns_zone_detach(&zone);
	return;

 notauth:
	notify_log(client, ISC_LOG_NOTICE,
		   "received notify for zone '%s'%s: not authoritative",
		   namebuf, tsigbuf);
	result = DNS_R_NOTAUTH;
	goto failure;

 formerr:
	result = DNS_R_FORMERR;

 failure:
	if (zone != NULL)
		dns_zone_detach(&zone);
	respond(client, result);
}