[master] DNS RRL

3494.	[func]		DNS RRL: Blunt the impact of DNS reflection and
			amplification attacks by rate-limiting substantially-
			identical responses. [RT #28130]

CHANGES

@@ -1,3 +1,7 @@
+3494.	[func]		DNS RRL: Blunt the impact of DNS reflection and
+			amplification attacks by rate-limiting substantially-
+			identical responses. [RT #28130]
+
 3493.	[contrib]	Added BDBHPT dynamically-lodable DLZ module,
 			contributed by Mark Goldfinch. [RT #32549]
 			

bin/named/client.c

@@ -1000,6 +1000,11 @@ client_send(ns_client_t *client) {
 	}
 	if (result != ISC_R_SUCCESS)
 		goto done;
+	/*
+	 * Stop after the question if TC was set for rate limiting.
+	 */
+	if ((client->message->flags & DNS_MESSAGEFLAG_TC) != 0)
+		goto renderend;
 	result = dns_message_rendersection(client->message,
 					   DNS_SECTION_ANSWER,
 					   DNS_MESSAGERENDER_PARTIAL |
@@ -1205,6 +1210,49 @@ ns_client_error(ns_client_t *client, isc_result_t result) {
 	}
 #endif
 
+	/*
+	 * Try to rate limit error responses.
+	 */
+	if (client->view != NULL && client->view->rrl != NULL) {
+		isc_boolean_t wouldlog;
+		char log_buf[DNS_RRL_LOG_BUF_LEN];
+		dns_rrl_result_t rrl_result;
+
+		INSIST(rcode != dns_rcode_noerror &&
+		       rcode != dns_rcode_nxdomain);
+		wouldlog = (ns_g_server->log_queries &&
+			    isc_log_wouldlog(ns_g_lctx, DNS_RRL_LOG_DROP));
+		rrl_result = dns_rrl(client->view, &client->peeraddr,
+				     TCP_CLIENT(client),
+				     dns_rdataclass_in, dns_rdatatype_none,
+				     NULL, result, client->now,
+				     wouldlog, log_buf, sizeof(log_buf));
+		if (rrl_result != DNS_RRL_RESULT_OK) {
+			/*
+			 * Log dropped errors in the query category
+			 * so that they are not lost in silence.
+			 * Starts of rate-limited bursts are logged in
+			 * NS_LOGCATEGORY_RRL.
+			 */
+			if (wouldlog) {
+				ns_client_log(client, NS_LOGCATEGORY_QUERIES,
+					      NS_LOGMODULE_CLIENT,
+					      DNS_RRL_LOG_DROP,
+					      "%s", log_buf);
+			}
+			/*
+			 * Some error responses cannot be 'slipped',
+			 * so don't try.
+			 * This will counted with dropped queries in the
+			 * QryDropped counter.
+			 */
+			if (!client->view->rrl->log_only) {
+				ns_client_next(client, DNS_R_DROP);
+				return;
+			}
+		}
+	}
+
 	/*
 	 * Message may be an in-progress reply that we had trouble
 	 * with, in which case QR will be set.  We need to clear QR before

bin/named/config.c

@@ -227,6 +227,13 @@ view \"_bind\" chaos {\n\
 	recursion no;\n\
 	notify no;\n\
 	allow-new-zones no;\n\
+\n\
+	# Prevent use of this zone in DNS amplified reflection DoS attacks\n\
+	rate-limit {\n\
+		responses-per-second 3;\n\
+		slip 0;\n\
+		min-table-size 10;\n\
+	};\n\
 \n\
 	zone \"version.bind\" chaos {\n\
 		type master;\n\

bin/named/include/named/query.h

@@ -85,6 +85,7 @@ struct ns_query {
 #define NS_QUERYATTR_CACHEACLOK		0x2000
 #define NS_QUERYATTR_DNS64		0x4000
 #define NS_QUERYATTR_DNS64EXCLUDE	0x8000
+#define NS_QUERYATTR_RRL_CHECKED	0x10000
 
 
 isc_result_t

bin/named/include/named/server.h

@@ -169,7 +169,10 @@ enum {
 
 	dns_nsstatscounter_dns64 = 37,
 
-	dns_nsstatscounter_max = 38
+	dns_nsstatscounter_ratedropped = 38,
+	dns_nsstatscounter_rateslipped = 39,
+
+	dns_nsstatscounter_max = 40
 };
 
 void

bin/named/query.c

@@ -5857,6 +5857,105 @@ query_find(ns_client_t *client, dns_fetchevent_t *event, dns_rdatatype_t qtype)
  resume:
 	CTRACE("query_find: resume");
 
+	/*
+	 * Rate limit these responses to this client.
+	 */
+	if (client->view->rrl != NULL &&
+	    fname != NULL && dns_name_isabsolute(fname) &&
+	    (client->query.attributes & NS_QUERYATTR_RRL_CHECKED) == 0) {
+		dns_rdataset_t nc_rdataset;
+		isc_boolean_t wouldlog;
+		char log_buf[DNS_RRL_LOG_BUF_LEN];
+		isc_result_t nc_result;
+		dns_rrl_result_t rrl_result;
+
+		client->query.attributes |= NS_QUERYATTR_RRL_CHECKED;
+
+		wouldlog = isc_log_wouldlog(ns_g_lctx, DNS_RRL_LOG_DROP);
+		tname = fname;
+		if (result == DNS_R_NXDOMAIN) {
+			/*
+			 * Use the database origin name to rate limit NXDOMAIN
+			 */
+			if (db != NULL)
+				tname = dns_db_origin(db);
+			rrl_result = result;
+		} else if (result == DNS_R_NCACHENXDOMAIN &&
+			   rdataset != NULL &&
+			   dns_rdataset_isassociated(rdataset) &&
+			   (rdataset->attributes &
+			    DNS_RDATASETATTR_NEGATIVE) != 0) {
+			/*
+			 * Try to use owner name in the negative cache SOA.
+			 */
+			dns_fixedname_init(&fixed);
+			dns_rdataset_init(&nc_rdataset);
+			for (nc_result = dns_rdataset_first(rdataset);
+			     nc_result == ISC_R_SUCCESS;
+			     nc_result = dns_rdataset_next(rdataset)) {
+				dns_ncache_current(rdataset,
+						   dns_fixedname_name(&fixed),
+						   &nc_rdataset);
+				if (nc_rdataset.type == dns_rdatatype_soa) {
+					dns_rdataset_disassociate(&nc_rdataset);
+					tname = dns_fixedname_name(&fixed);
+					break;
+				}
+				dns_rdataset_disassociate(&nc_rdataset);
+			}
+			rrl_result = DNS_R_NXDOMAIN;
+		} else if (result == DNS_R_DELEGATION) {
+			rrl_result = result;
+		} else {
+			rrl_result = ISC_R_SUCCESS;
+		}
+		rrl_result = dns_rrl(client->view, &client->peeraddr,
+				     ISC_TF((client->attributes
+					     & NS_CLIENTATTR_TCP) != 0),
+				     client->message->rdclass, qtype, tname,
+				     rrl_result, client->now,
+				     wouldlog, log_buf, sizeof(log_buf));
+		if (rrl_result != DNS_RRL_RESULT_OK) {
+			/*
+			 * Log dropped or slipped responses in the query
+			 * category so that requests are not silently lost.
+			 * Starts of rate-limited bursts are logged in
+			 * DNS_LOGCATEGORY_RRL.
+			 *
+			 * Dropped responses are counted with dropped queries
+			 * in QryDropped while slipped responses are counted
+			 * with other truncated responses in RespTruncated.
+			 */
+			if (wouldlog && ns_g_server->log_queries) {
+				ns_client_log(client, NS_LOGCATEGORY_QUERIES,
+					      NS_LOGMODULE_CLIENT,
+					      DNS_RRL_LOG_DROP,
+					      "%s", log_buf);
+			}
+			if (!client->view->rrl->log_only) {
+				if (rrl_result == DNS_RRL_RESULT_DROP) {
+					/*
+					 * These will also be counted in
+					 * dns_nsstatscounter_dropped
+					 */
+					inc_stats(client,
+						dns_nsstatscounter_ratedropped);
+					QUERY_ERROR(DNS_R_DROP);
+				} else {
+					/*
+					 * These will also be counted in
+					 * dns_nsstatscounter_truncatedresp
+					 */
+					inc_stats(client,
+						dns_nsstatscounter_rateslipped);
+					client->message->flags |=
+						DNS_MESSAGEFLAG_TC;
+				}
+				goto cleanup;
+			}
+		}
+	}
+
 	if (!ISC_LIST_EMPTY(client->view->rpz_zones) &&
 	    (RECURSIONOK(client) || !client->view->rpz_recursive_only) &&
 	    rpz_ck_dnssec(client, result, rdataset, sigrdataset) &&
@@ -7321,12 +7420,14 @@ query_find(ns_client_t *client, dns_fetchevent_t *event, dns_rdatatype_t qtype)
 	}
 
 	if (eresult != ISC_R_SUCCESS &&
-	    (!PARTIALANSWER(client) || WANTRECURSION(client))) {
+	    (!PARTIALANSWER(client) || WANTRECURSION(client)
+	     || eresult == DNS_R_DROP)) {
 		if (eresult == DNS_R_DUPLICATE || eresult == DNS_R_DROP) {
 			/*
 			 * This was a duplicate query that we are
-			 * recursing on.  Don't send a response now.
+			 * recursing on or the result of rate limiting.
-			 * The original query will still cause a response.
+			 * Don't send a response now for a duplicate query,
+			 * because the original will still cause a response.
 			 */
 			query_next(client, eresult);
 		} else {

bin/named/server.c

@@ -1678,6 +1678,199 @@ configure_rpz(dns_view_t *view, const cfg_listelt_t *element,
 	return (result);
 }
 
+#define CHECK_RRL(obj, cond, pat, val1, val2)				\
+	do {								\
+		if (!(cond)) {						\
+			cfg_obj_log(obj, ns_g_lctx, ISC_LOG_ERROR,	\
+				    pat, val1, val2);			\
+			result = ISC_R_RANGE;				\
+			goto cleanup;					\
+		    }							\
+	} while (0)
+
+static isc_result_t
+configure_rrl(dns_view_t *view, const cfg_obj_t *config, const cfg_obj_t *map) {
+	const cfg_obj_t *obj;
+	dns_rrl_t *rrl;
+	isc_result_t result;
+ 	int min_entries, i, j;
+
+	/*
+	 * Most DNS servers have few clients, but intentinally open
+	 * recursive and authoritative servers often have many.
+	 * So start with a small number of entries unless told otherwise
+	 * to reduce cold-start costs.
+	 */
+	min_entries = 500;
+	obj = NULL;
+	result = cfg_map_get(map, "min-table-size", &obj);
+	if (result == ISC_R_SUCCESS) {
+		min_entries = cfg_obj_asuint32(obj);
+		if (min_entries < 1)
+			min_entries = 1;
+	}
+	result = dns_rrl_init(&rrl, view, min_entries);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+
+	i = ISC_MAX(20000, min_entries);
+	obj = NULL;
+	result = cfg_map_get(map, "max-table-size", &obj);
+	if (result == ISC_R_SUCCESS) {
+		i = cfg_obj_asuint32(obj);
+		CHECK_RRL(obj, i >= min_entries,
+			  "max-table-size %d < min-table-size %d",
+			  i, min_entries);
+	}
+	rrl->max_entries = i;
+
+	i = 0;
+	obj = NULL;
+	result = cfg_map_get(map, "responses-per-second", &obj);
+	if (result == ISC_R_SUCCESS) {
+		i = cfg_obj_asuint32(obj);
+		CHECK_RRL(obj, i <= DNS_RRL_MAX_RATE,
+			  "responses-per-second %d > %d",
+			  i, DNS_RRL_MAX_RATE);
+	}
+	rrl->responses_per_second = i;
+	rrl->scaled_responses_per_second = rrl->responses_per_second;
+
+	/*
+	 * The default error rate is the response rate,
+	 * and so off by default.
+	 */
+	i = rrl->responses_per_second;
+	obj = NULL;
+	result = cfg_map_get(map, "errors-per-second", &obj);
+	if (result == ISC_R_SUCCESS) {
+		i = cfg_obj_asuint32(obj);
+		CHECK_RRL(obj, i <= DNS_RRL_MAX_RATE,
+			  "errors-per-second %d > %d",
+			  i, DNS_RRL_MAX_RATE);
+	}
+	rrl->errors_per_second = i;
+	rrl->scaled_errors_per_second = rrl->errors_per_second;
+	/*
+	 * The default NXDOMAIN rate is the response rate,
+	 * and so off by default.
+	 */
+	i = rrl->responses_per_second;
+	obj = NULL;
+	result = cfg_map_get(map, "nxdomains-per-second", &obj);
+	if (result == ISC_R_SUCCESS) {
+		i = cfg_obj_asuint32(obj);
+		CHECK_RRL(obj, i <= DNS_RRL_MAX_RATE,
+			  "nxdomains-per-second %d > %d",
+			  i, DNS_RRL_MAX_RATE);
+	}
+	rrl->nxdomains_per_second = i;
+	rrl->scaled_nxdomains_per_second = rrl->nxdomains_per_second;
+
+	/*
+	 * The all-per-second rate is off by default.
+	 */
+	i = 0;
+	obj = NULL;
+	result = cfg_map_get(map, "all-per-second", &obj);
+	if (result == ISC_R_SUCCESS) {
+		i = cfg_obj_asuint32(obj);
+		CHECK_RRL(obj, i <= DNS_RRL_MAX_RATE, "all-per-second %d > %d",
+			  i, DNS_RRL_MAX_RATE);
+	}
+	rrl->all_per_second = i;
+	rrl->scaled_all_per_second = rrl->all_per_second;
+
+	i = 2;
+	obj = NULL;
+	result = cfg_map_get(map, "slip", &obj);
+	if (result == ISC_R_SUCCESS) {
+		i = cfg_obj_asuint32(obj);
+		CHECK_RRL(obj, i <= DNS_RRL_MAX_SLIP,
+			  "slip %d > %d", i, DNS_RRL_MAX_SLIP);
+	}
+	rrl->slip = i;
+	rrl->scaled_slip = rrl->slip;
+
+	i = 15;
+	obj = NULL;
+	result = cfg_map_get(map, "window", &obj);
+	if (result == ISC_R_SUCCESS) {
+		i = cfg_obj_asuint32(obj);
+		CHECK_RRL(obj, i >= 1 && i <= DNS_RRL_MAX_WINDOW,
+			  "window %d < 1 or > %d", i, DNS_RRL_MAX_WINDOW);
+	}
+	rrl->window = i;
+
+	i = 0;
+	obj = NULL;
+	result = cfg_map_get(map, "qps-scale", &obj);
+	if (result == ISC_R_SUCCESS) {
+		i = cfg_obj_asuint32(obj);
+		CHECK_RRL(obj, i >= 1, "invalid 'qps-scale %d'%s", i, "");
+	}
+	rrl->qps_scale = i;
+	rrl->qps = 1.0;
+
+	i = 24;
+	obj = NULL;
+	result = cfg_map_get(map, "IPv4-prefix-length", &obj);
+	if (result == ISC_R_SUCCESS) {
+		i = cfg_obj_asuint32(obj);
+		CHECK_RRL(obj, i >= 8 && i <= 32,
+			  "invalid 'IPv4-prefix-length %d'%s", i, "");
+	}
+	rrl->ipv4_prefixlen = i;
+	if (i == 32)
+		rrl->ipv4_mask = 0xffffffff;
+	else
+		rrl->ipv4_mask = htonl(0xffffffff << (32-i));
+
+	i = 56;
+	obj = NULL;
+	result = cfg_map_get(map, "IPv6-prefix-length", &obj);
+	if (result == ISC_R_SUCCESS) {
+		i = cfg_obj_asuint32(obj);
+		CHECK_RRL(obj, i >= 16 && i <= DNS_RRL_MAX_PREFIX,
+			  "IPv6-prefix-length %d < 16 or > %d",
+			  i, DNS_RRL_MAX_PREFIX);
+	}
+	rrl->ipv6_prefixlen = i;
+	for (j = 0; j < 4; ++j) {
+		if (i <= 0) {
+			rrl->ipv6_mask[j] = 0;
+		} else if (i < 32) {
+			rrl->ipv6_mask[j] = htonl(0xffffffff << (32-i));
+		} else {
+			rrl->ipv6_mask[j] = 0xffffffff;
+		}
+		i -= 32;
+	}
+
+	obj = NULL;
+	result = cfg_map_get(map, "exempt-clients", &obj);
+	if (result == ISC_R_SUCCESS) {
+		result = cfg_acl_fromconfig(obj, config, ns_g_lctx,
+					    ns_g_aclconfctx, ns_g_mctx,
+					    0, &rrl->exempt);
+		CHECK_RRL(obj, result == ISC_R_SUCCESS,
+			  "invalid %s%s", "address match list", "");
+	}
+
+	obj = NULL;
+	result = cfg_map_get(map, "log-only", &obj);
+	if (result == ISC_R_SUCCESS && cfg_obj_asboolean(obj))
+		rrl->log_only = ISC_TRUE;
+	else
+		rrl->log_only = ISC_FALSE;
+
+	return (ISC_R_SUCCESS);
+
+ cleanup:
+	dns_rrl_view_destroy(view);
+	return (result);
+}
+
 /*
  * Configure 'view' according to 'vconfig', taking defaults from 'config'
  * where values are missing in 'vconfig'.
@@ -3100,6 +3293,14 @@ configure_view(dns_view_t *view, cfg_obj_t *config, cfg_obj_t *vconfig,
 		}
 	}
 
+	obj = NULL;
+	result = ns_config_get(maps, "rate-limit", &obj);
+	if (result == ISC_R_SUCCESS) {
+		result = configure_rrl(view, config, obj);
+		if (result != ISC_R_SUCCESS)
+			goto cleanup;
+	}
+
 	result = ISC_R_SUCCESS;
 
  cleanup:

bin/named/statschannel.c

@@ -207,6 +207,10 @@ init_desc(void) {
 	SET_NSSTATDESC(recursclients, "recursing clients",
 			"RecursClients");
 	SET_NSSTATDESC(dns64, "queries answered by DNS64", "DNS64");
+	SET_NSSTATDESC(ratedropped, "responses dropped for rate limits",
+		       "RateDropped");
+	SET_NSSTATDESC(rateslipped, "responses truncated for rate limits",
+		       "RateSlipped");
 	INSIST(i == dns_nsstatscounter_max);
 
 	/* Initialize resolver statistics */

bin/tests/system/README

@@ -17,6 +17,7 @@ involving a different DNS setup.  They are:
   nsupdate/	Dynamic update and IXFR tests
   resolver/     Regression tests for resolver bugs that have been fixed
 		(not a complete resolver test suite)
+  rrl/		query rate limiting
   rpz/		Tests of response policy zone (RPZ) rewriting
   stub/		Tests of stub zone functionality
   unknown/	Unknown type and class tests

bin/tests/system/conf.sh.in

@@ -61,7 +61,7 @@ SUBDIRS="acl additional allow_query addzone autosign builtin
 	 dsdigest ecdsa formerr forward glue gost ixfr inline limits
 	 logfileconfig lwresd masterfile masterformat metadata
 	 notify nsupdate pending pkcs11 redirect resolver rndc rpz
-	 rrsetorder rsabigexponent sortlist smartsign staticstub
+	 rrl rrsetorder rsabigexponent sortlist smartsign staticstub
 	 statistics stub tkey tsig tsiggss unknown upforwd verify
 	 views wildcard xfer xferquota zonechecks"
 

bin/tests/system/rrl/.gitignore

@@ -0,0 +1 @@
+flood

bin/tests/system/rrl/clean.sh

@@ -0,0 +1,21 @@
+# Copyright (C) 2012-2013  Internet Systems Consortium, Inc. ("ISC")
+#
+# Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
+# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+# AND FITNESS.  IN NO EVENT SHALL ISC 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.
+
+
+
+# Clean up after rrl tests.
+
+rm -f dig.out*
+rm -f  */named.memstats */named.run */named.stats */log */session.key
+rm -f ns3/bl*.db */*.jnl */*.core */*.pid

bin/tests/system/rrl/ns1/named.conf

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2012-2013  Internet Systems Consortium, Inc. ("ISC")
+ *
+ * Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC 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.
+ */
+
+
+controls { /* empty */ };
+
+options {
+	query-source address 10.53.0.1;
+	notify-source 10.53.0.1;
+	transfer-source 10.53.0.1;
+	port 5300;
+	session-keyfile "session.key";
+	pid-file "named.pid";
+	listen-on { 10.53.0.1; };
+	listen-on-v6 { none; };
+	notify no;
+};
+
+zone "." {type master; file "root.db";};

bin/tests/system/rrl/ns1/root.db

@@ -0,0 +1,31 @@
+; Copyright (C) 2012-2013  Internet Systems Consortium, Inc. ("ISC")
+;
+; Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
+; REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+; AND FITNESS.  IN NO EVENT SHALL ISC 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.
+
+
+$TTL	120
+@		SOA	ns. hostmaster.ns. ( 1 3600 1200 604800 60 )
+@		NS	ns.
+ns.		A	10.53.0.1
+.		A	10.53.0.1
+
+; limit responses from here
+tld2.		NS	ns.tld2.
+ns.tld2.	A	10.53.0.2
+
+; limit recursion to here
+tld3.		NS	ns.tld3.
+ns.tld3.	A	10.53.0.3
+
+; generate SERVFAIL
+tld4.		NS	ns.tld3.

bin/tests/system/rrl/ns2/hints

@@ -0,0 +1,18 @@
+; Copyright (C) 2012-2013  Internet Systems Consortium, Inc. ("ISC")
+;
+; Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
+; REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+; AND FITNESS.  IN NO EVENT SHALL ISC 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.
+
+
+
+.	0	NS	ns1.
+ns1.	0	A	10.53.0.1

bin/tests/system/rrl/ns2/named.conf

@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2012-2013  Internet Systems Consortium, Inc. ("ISC")
+ *
+ * Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC 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.
+ */
+
+
+controls { /* empty */ };
+
+options {
+	query-source address 10.53.0.2;
+	notify-source 10.53.0.2;
+	transfer-source 10.53.0.2;
+	port 5300;
+	session-keyfile "session.key";
+	pid-file "named.pid";
+	statistics-file	"named.stats";
+	listen-on { 10.53.0.2; };
+	listen-on-v6 { none; };
+	notify no;
+
+	rate-limit {
+	    responses-per-second 2;
+	    all-per-second 70;
+	    IPv4-prefix-length 24;
+	    IPv6-prefix-length 64;
+	    slip 3;
+	    /* qps-scale 2; */
+	    exempt-clients { 10.53.0.7; };
+	    window 1;
+	    max-table-size 100;
+	    min-table-size 2;
+	};
+};
+
+key rndc_key {
+	secret "1234abcd8765";
+	algorithm hmac-md5;
+};
+controls {
+	inet 10.53.0.2 port 9953 allow { any; } keys { rndc_key; };
+};
+
+/*
+ * These log settings have no effect unless "-g" is removed from ../../start.pl
+ */
+logging {
+	channel debug {
+	    file "log-debug";
+	    print-category yes; print-severity yes; severity debug 10;
+	};
+	channel queries {
+	    file "log-queries";
+	    print-category yes; print-severity yes; severity info;
+	};
+	category rate-limit { debug; queries; };
+	category queries { debug; queries; };
+};
+
+zone "." { type hint; file "hints"; };
+
+zone "tld2."{ type master; file "tld2.db"; };

bin/tests/system/rrl/ns2/tld2.db

@@ -0,0 +1,42 @@
+; Copyright (C) 2012-2013  Internet Systems Consortium, Inc. ("ISC")
+;
+; Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
+; REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+; AND FITNESS.  IN NO EVENT SHALL ISC 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.
+
+
+
+; rate limit response from this zone
+
+$TTL	120
+@		SOA	tld2.  hostmaster.ns.tld2. ( 1 3600 1200 604800 60 )
+		NS	ns
+		NS	.
+ns		A	10.53.0.2
+
+a1		A	192.168.2.1
+
+*.a2		A	192.168.2.2
+
+; a3 is in tld3
+
+; a4 does not exist to give NXDOMAIN
+
+; a5 for TCP requests
+a5		A	192.168.2.5
+
+; a6 for whitelisted clients
+a6		A	192.168.2.6
+
+; a7 for SERVFAIL
+
+; a8 for all-per-second limit
+$GENERATE 101-180 all$.a8 A 192.168.2.8

bin/tests/system/rrl/ns3/hints

@@ -0,0 +1,18 @@
+; Copyright (C) 2012-2013  Internet Systems Consortium, Inc. ("ISC")
+;
+; Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
+; REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+; AND FITNESS.  IN NO EVENT SHALL ISC 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.
+
+
+
+.	0	NS	ns1.
+ns1.	0	A	10.53.0.1

bin/tests/system/rrl/ns3/named.conf

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2012-2013  Internet Systems Consortium, Inc. ("ISC")
+ *
+ * Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC 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.
+ */
+
+
+controls { /* empty */ };
+
+options {
+	query-source address 10.53.0.3;
+	notify-source 10.53.0.3;
+	transfer-source 10.53.0.3;
+	port 5300;
+	session-keyfile "session.key";
+	pid-file "named.pid";
+	listen-on { 10.53.0.3; };
+	listen-on-v6 { none; };
+	notify no;
+};
+
+zone "." { type hint; file "hints"; };
+
+zone "tld3."{ type master; file "tld3.db"; };

bin/tests/system/rrl/ns3/tld3.db

@@ -0,0 +1,25 @@
+; Copyright (C) 2012-2013  Internet Systems Consortium, Inc. ("ISC")
+;
+; Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
+; REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+; AND FITNESS.  IN NO EVENT SHALL ISC 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.
+
+
+
+; rate limit response from this zone
+
+$TTL	120
+@		SOA	tld3.  hostmaster.ns.tld3. ( 1 3600 1200 604800 60 )
+		NS	ns
+		NS	.
+ns		A	10.53.0.3
+
+*.a3		A	192.168.3.3

bin/tests/system/rrl/setup.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+#
+# Copyright (C) 2012-2013  Internet Systems Consortium, Inc. ("ISC")
+#
+# Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
+# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+# AND FITNESS.  IN NO EVENT SHALL ISC 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.
+
+
+SYSTEMTESTTOP=..
+. $SYSTEMTESTTOP/conf.sh
+. ./clean.sh
+

bin/tests/system/rrl/tests.sh

@@ -0,0 +1,224 @@
+# Copyright (C) 2012-2013  Internet Systems Consortium, Inc. ("ISC")
+#
+# Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
+# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+# AND FITNESS.  IN NO EVENT SHALL ISC 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.
+
+
+# test response rate limiting
+
+SYSTEMTESTTOP=..
+. $SYSTEMTESTTOP/conf.sh
+
+#set -x
+#set -o noclobber
+
+ns1=10.53.0.1			    # root, defining the others
+ns2=10.53.0.2			    # test server
+ns3=10.53.0.3			    # secondary test server
+ns7=10.53.0.7			    # whitelisted client
+
+USAGE="$0: [-x]"
+while getopts "x" c; do
+    case $c in
+	x) set -x;;
+	*) echo "$USAGE" 1>&2; exit 1;;
+    esac
+done
+shift `expr $OPTIND - 1 || true`
+if test "$#" -ne 0; then
+    echo "$USAGE" 1>&2
+    exit 1
+fi
+# really quit on control-C
+trap 'exit 1' 1 2 15
+
+
+ret=0
+setret () {
+    ret=1
+    echo "$*"
+}
+
+
+# Wait until soon after the start of a second to make results consistent.
+#   The start of a second credits a rate limit.
+#   This would be far easier in C or by assuming a modern version of perl.
+sec_start () {
+    START=`date`
+    while true; do
+	NOW=`date`
+	if test "$START" != "$NOW"; then
+	    return
+	fi
+	$PERL -e 'select(undef, undef, undef, 0.05)' || true
+    done
+}
+
+
+#   $1=result name  $2=domain name  $3=dig options
+digcmd () {
+    OFILE=$1; shift
+    DIG_DOM=$1; shift
+    ARGS="+noadd +noauth +nosearch +time=1 +tries=1 +ignore $* -p 5300 $DIG_DOM @$ns2"
+    #echo I:dig $ARGS 1>&2
+    START=`date +%y%m%d%H%M.%S`
+    RESULT=`$DIG $ARGS 2>&1 | tee $OFILE=TEMP				\
+	    | sed -n -e  's/^[^;].*	\([^	 ]\{1,\}\)$/\1/p'	\
+		-e 's/;; flags.* tc .*/TC/p'				\
+		-e 's/;; .* status: NXDOMAIN.*/NXDOMAIN/p'		\
+		-e 's/;; .* status: SERVFAIL.*/SERVFAIL/p'		\
+		-e 's/;; connection timed out.*/drop/p'			\
+		-e 's/;; communications error to.*/drop/p'		\
+	    | tr -d '\n'`
+    mv "$OFILE=TEMP" "$OFILE=$RESULT"
+    touch -t $START "$OFILE=$RESULT"
+}
+
+
+#   $1=number of tests  $2=target domain  $3=dig options
+CNT=1
+burst () {
+    BURST_LIMIT=$1; shift
+    BURST_DOM_BASE="$1"; shift
+    while test "$BURST_LIMIT" -ge 1; do
+	if test $CNT -lt 10; then
+	    CNT="00$CNT"
+	else
+	    if test $CNT -lt 100; then
+		CNT="0$CNT"
+	    fi
+	fi
+	eval BURST_DOM="$BURST_DOM_BASE"
+	FILE="dig.out-$BURST_DOM-$CNT"
+	digcmd $FILE $BURST_DOM $* &
+	CNT=`expr $CNT + 1`
+	BURST_LIMIT=`expr "$BURST_LIMIT" - 1`
+    done
+}
+
+
+#   $1=domain  $2=IP address  $3=# of IP addresses  $4=TC  $5=drop
+#	$6=NXDOMAIN  $7=SERVFAIL or other errors
+ck_result() {
+    BAD=
+    wait
+    ADDRS=`ls dig.out-$1-*=$2		2>/dev/null	| wc -l | tr -d ' '`
+    TC=`ls dig.out-$1-*=TC		2>/dev/null	| wc -l | tr -d ' '`
+    DROP=`ls dig.out-$1-*=drop		2>/dev/null	| wc -l | tr -d ' '`
+    NXDOMAIN=`ls dig.out-$1-*=NXDOMAIN	2>/dev/null	| wc -l | tr -d ' '`
+    SERVFAIL=`ls dig.out-$1-*=SERVFAIL	2>/dev/null	| wc -l | tr -d ' '`
+    if test $ADDRS -ne "$3"; then
+	setret "I:$ADDRS instead of $3 $2 responses for $1"
+	BAD=yes
+    fi
+    if test $TC -ne "$4"; then
+	setret "I:$TC instead of $4 truncation responses for $1"
+	BAD=yes
+    fi
+    if test $DROP -ne "$5"; then
+	setret "I:$DROP instead of $5 dropped responses for $1"
+	BAD=yes
+    fi
+    if test $NXDOMAIN -ne "$6"; then
+	setret "I:$NXDOMAIN instead of $6 NXDOMAIN responses for $1"
+	BAD=yes
+    fi
+    if test $SERVFAIL -ne "$7"; then
+	setret "I:$SERVFAIL instead of $7 error responses for $1"
+	BAD=yes
+    fi
+    if test -z "$BAD"; then
+	rm -f dig.out-$1-*
+    fi
+}
+
+
+#########
+sec_start
+
+# basic rate limiting
+burst 3 a1.tld2
+# 1 second delay allows an additional response.
+sleep 1
+burst 21 a1.tld2
+# request 30 different qnames to try a wild card
+burst 30 'x$CNT.a2.tld2'
+
+#					IP      TC      drop  NXDOMAIN SERVFAIL
+# check for 24 results
+# including the 1 second delay
+ck_result   a1.tld2	192.168.2.1	3	7	14	0	0
+
+# Check the wild card answers.
+# The parent name of the 30 requests is counted.
+ck_result 'x*.a2.tld2'	192.168.2.2	2	10	18	0	0
+
+
+#########
+sec_start
+
+burst 1 'y$CNT.a3.tld3'; wait; burst 20 'y$CNT.a3.tld3'
+burst 20 'z$CNT.a4.tld2'
+
+# Recursion.
+#   The first answer is counted separately because it is counted against
+#   the rate limit on recursing to the server for a3.tld3.  The remaining 20
+#   are counted as local responses from the cache.
+ck_result 'y*.a3.tld3'	192.168.3.3	3	6	12	0	0
+
+# NXDOMAIN responses are also limited based on the parent name.
+ck_result 'z*.a4.tld2'	x		0	6	12	2	0
+
+
+#########
+sec_start
+
+burst 20 a5.tld2 +tcp
+burst 20 a6.tld2 -b $ns7
+burst 20 a7.tld4
+
+# TCP responses are not rate limited
+ck_result a5.tld2	192.168.2.5	20	0	0	0	0
+
+# whitelisted client is not rate limited
+ck_result a6.tld2	192.168.2.6	20	0	0	0	0
+
+# Errors such as SERVFAIL are rate limited.  The numbers are confusing, because
+#   other rate limiting can be triggered before the SERVFAIL limit is reached.
+ck_result a7.tld4	192.168.2.1	0	6	12	0	2
+
+
+#########
+sec_start
+
+# all-per-second
+#   The qnames are all unique but the client IP address is constant.
+CNT=101
+burst 80 'all$CNT.a8.tld2'
+ck_result 'a*.a8.tld2'	192.168.2.8	70	0	10	0	0
+
+
+$RNDC -c $SYSTEMTESTTOP/common/rndc.conf -p 9953 -s $ns2 stats
+ckstats () {
+    CNT=`sed -n -e "s/[	 ]*\([0-9]*\).responses $1 for rate limits.*/\1/p"  \
+		ns2/named.stats`
+    CNT=`expr 0$CNT + 0`
+    if test "$CNT" -ne $2; then
+	setret "I:wrong $1 statistics of $CNT instead of $2"
+    fi
+}
+ckstats dropped 77
+ckstats truncated 35
+
+
+echo "I:exit status: $ret"
+exit $ret

doc/arm/Bv9ARM-book.xml

@@ -4826,6 +4826,34 @@ category notify { null; };
 		    </para>
 		  </entry>
 		</row>
+                <row rowsep="0">
+                  <entry colname="1">
+                    <para><command>rate-limit</command></para>
+                  </entry>
+		  <entry colname="2">
+		    <para>
+		      The start, periodic, and final notices of the
+		      rate limiting of a stream of responses are logged at
+		      <command>info</command> severity in this category.
+		      These messages include a hash value of the domain name
+		      of the response and the name itself,
+		      except when there is insufficient memory to record
+		      the name for the final notice
+		      The final notice is normally delayed until about one
+		      minute after rate limit stops.
+		      A lack of memory can hurry the final notice,
+		      in which case it starts with an asterisk (*).
+		      Various internal events are logged at debug 1 level
+		      and higher.
+		    </para>
+		    <para>
+		      Rate limiting of individual requests
+		      is logged in the <command>queries</command> category
+		      and can be controlled with the
+		      <command>querylog</command> option.
+		    </para>
+		  </entry>
+		</row>
 	      </tbody>
 	    </tgroup>
 	  </informaltable>
@@ -5361,6 +5389,21 @@ badresp:1,adberr:0,findfail:0,valfail:0]
     <optional> resolver-query-timeout <replaceable>number</replaceable> ; </optional>
     <optional> deny-answer-addresses { <replaceable>address_match_list</replaceable> } <optional> except-from { <replaceable>namelist</replaceable> } </optional>;</optional>
     <optional> deny-answer-aliases { <replaceable>namelist</replaceable> } <optional> except-from { <replaceable>namelist</replaceable> } </optional>;</optional>
+    <optional> rate-limit {
+	<optional> responses-per-second <replaceable>number</replaceable> ; </optional>
+	<optional> errors-per-second <replaceable>number</replaceable> ; </optional>
+	<optional> nxdomains-per-second <replaceable>number</replaceable> ; </optional>
+	<optional> all-per-second <replaceable>number</replaceable> ; </optional>
+	<optional> window <replaceable>number</replaceable> ; </optional>
+	<optional> log-only <replaceable>yes_or_no</replaceable> ; </optional>
+	<optional> qps-scale <replaceable>number</replaceable> ; </optional>
+	<optional> IPv4-prefix-length <replaceable>number</replaceable> ; </optional>
+	<optional> IPv6-prefix-length <replaceable>number</replaceable> ; </optional>
+	<optional> slip <replaceable>number</replaceable> ; </optional>
+	<optional> exempt-clients  { <replaceable>address_match_list</replaceable> } ; </optional>
+	<optional> max-table-size <replaceable>number</replaceable> ; </optional>
+	<optional> min-table-size <replaceable>number</replaceable> ; </optional>
+      } ; </optional>
     <optional> response-policy { <replaceable>zone_name</replaceable>
 	<optional> policy given | disabled | passthru | nxdomain | nodata | cname <replaceable>domain</replaceable> </optional>
 	<optional> recursive-only <replaceable>yes_or_no</replaceable> </optional> <optional> max-policy-ttl <replaceable>number</replaceable> </optional> ;
@@ -9898,6 +9941,215 @@ ns.domain.com.rpz-nsdname   CNAME   .
             have a maximum QPS rate about 50% lower.
 	  </para>
         </sect3>
+
+	<sect3>
+	  <title>Rate Limiting</title>
+	  <para>
+	    Excessive essentially identical UDP <emphasis>responses</emphasis>
+	    can be discarded by configuring a
+	    <command>rate-limit</command> clause in an
+	    <command>options</command> statement.
+	    This mechanism keeps BIND 9 from being used
+	    in amplifying reflection denial of service attacks
+	    as well as partially protecting BIND 9 itself from
+	    some denial of service attacks.
+	    Very short truncated responses can be sent to provide
+	    rate-limited responses to legitimate
+	    clients within a range of attacked and forged IP addresses,
+	    Legitimate clients react to truncated response by retrying
+	    with TCP.
+	  </para>
+
+	  <para>
+	    Rate limiting works by setting
+	    <command>responses-per-second</command>
+	    to a number of repetitions per second for responses for a given name
+	    and record type to a DNS client.
+	  </para>
+
+	  <para>
+	    <command>Responses-per-second</command> is a limit on
+	    identical responses instead of a limit on all responses or
+	    even all responses to a single client.
+	    10 identical responses per second is a generous limit except perhaps
+	    when many clients are using a single IP address via network
+	    address translation (NAT).
+	    The default limit of zero specifies an unbounded limit to turn off
+	    rate-limiting in a view or to only rate-limit NXDOMAIN or other
+	    errors.
+	  </para>
+
+	  <para>
+	    The notion of "identical responses"
+	    and "single DNS client" cannot be simplistic.
+	    All responses to a CIDR block with prefix
+	    length specified with <command>IPv4-prefix-length</command>
+	    (default 24) or <command>IPv6-prefix-length</command>
+	    (default 56) are assumed to come from a single DNS client.
+	    Requests for a name that result in DNS NXDOMAIN
+	    errors are considered identical.
+	    This controls some attacks using random names, but
+	    accommodates servers that expect many legitimate NXDOMAIN responses
+	    such as anti-spam blacklists.
+	    By default the limit on NXDOMAIN errors is the same as the
+	    <command>responses-per-second</command> value,
+	    but it can be set separately with
+	    <command>nxdomains-per-second</command>.
+	    All requests for all names or types that result in DNS errors
+	    such as SERVFAIL and FORMERR (but not NXDOMAIN) are considered
+	    identical.
+	    This controls attacks using invalid requests or distant,
+	    broken authoritative servers.
+	    By default the limit on errors is the same as the
+	    <command>responses-per-second</command> value,
+	    but it can be set separately with
+	    <command>errors-per-second</command>.
+	  </para>
+
+	  <para>
+	    Rate limiting uses a "credit" or "token bucket" scheme.
+	    Each identical response has a conceptual account
+	    that is given <command>responses-per-second</command>,
+	    <command>errors-per-second</command>, and
+	    <command>nxdomains-per-second</command> credits every second.
+	    A DNS request triggering some desired response debits
+	    the account by one.
+	    Responses are not sent while the account is negative.
+	    The account cannot become more positive than
+	    the per-second limit
+	    or more negative than <command>window</command>
+	    times the per-second limit.
+	    A DNS client that sends requests that are not
+	    answered can be penalized for up to <command>window</command>
+	    seconds (default 15).
+	  </para>
+
+	  <para>
+	    Responses generated from local wildcards are counted and limited
+	    as if they were for the parent domain name.
+	    This prevents flooding by requesting random.wild.example.com.
+	    For similar reasons, NXDOMAIN responses are counted and rate
+	    limited by the valid domain name nearest to the
+	    query name with an SOA record.
+	  </para>
+
+	  <para>
+	    Many attacks using DNS involve UDP requests with forged source
+	    addresses.
+	    Rate limiting prevents the use of BIND 9 to flood a network
+	    with responses to requests with forged source addresses,
+	    but could let a third party block responses to legitimate requests.
+	    There is a mechanism that can answer some legitimate
+	    requests from a client whose address is being forged in a flood.
+	    Setting <command>slip</command> to 2 (its default) causes every
+	    other UDP request to be answered with a small response
+	    claiming that the response would have been truncated.
+	    The small size and relative infrequency of the response make
+	    it unattractive for abuse.
+	    <command>Slip</command> must be between 0 and 10.
+	    A value of 0 does not "slip"
+	    or sends no rate limiting truncated responses.
+	    Some error responses includinge REFUSED and SERVFAIL
+	    cannot be replaced with truncated responses and are instead
+	    leaked at the <command>slip</command> rate.
+	  </para>
+
+	  <para>
+	    When the approximate query per second rate exceeds
+	    the <command>qps-scale</command> value,
+	    then the <command>responses-per-second</command>,
+	    <command>errors-per-second</command>,
+	    <command>nxdomains-per-second</command> and
+	    <command>all-per-second</command> values are reduced by the
+	    ratio of the current rate to the <command>qps-scale</command> value.
+	    This feature can tighten defenses during attacks.
+	    For example, with
+	    <command>qps-scale 250; responses-per-second 20;</command> and
+	    a total query rate of 1000 queries/second for all queries from
+	    all DNS clients including via TCP,
+	    then the effective responses/second limit changes to
+	    (250/1000)*20 or 5.
+	    Responses sent via TCP are not limited
+	    but are counted to compute the query per second rate.
+	  </para>
+
+	  <para>
+	    Communities of DNS clients can be given their own parameters or no
+	    rate limiting by putting
+	    <command>rate-limit</command> statements in <command>view</command>
+	    statements instead of the global <command>option</command>
+	    statement.
+	    A <command>rate-limit</command> statement in a view replaces
+	    instead of being merged with a <command>rate-limit</command>
+	    statement among the main options.
+	    DNS clients within a view can be exempted from rate limits
+	    with the <command>exempt-clients</command> clause.
+	  </para>
+
+	  <para>
+	    UDP responses of all kinds can be limited with the
+	    <command>all-per-second</command> phrase.
+	    This rate limiting is unlike the rate limiting provided by
+	    <command>responses-per-second</command>,
+	    <command>errors-per-second</command>, and
+	    <command>nxdomains-per-second</command> on a DNS server
+	    which are often invisible to the victim of a DNS reflection attack.
+	    Unless the forged requests of the attack are the same as the
+	    legitimate requests of the victim, the victim's requests are
+	    not affected.
+	    Responses affected by an <command>all-per-second</command> limit
+	    are always dropped; the <command>slip</command> value has no
+	    effect.
+	    An <command>all-per-second</command> limit should be
+	    at least 4 times as large as the other limits,
+	    because single DNS clients often send bursts of legitimate
+	    requests.
+	    For example, the receipt of a single mail message can prompt
+	    requests from an SMTP server for NS, PTR, A, and AAAA records
+	    as the incoming SMTP/TCP/IP connection is considered.
+	    The SMTP server can need additional NS, A, AAAA, MX, TXT, and SPF
+	    records as it considers the STMP <command>Mail From</command>
+	    command.
+	    Web browsers often repeatedly resolve the same names that
+	    are repeated in HTML &lt;IMG&gt; tags in a page.
+	    <command>All-per-second</command> is similar to the
+	    rate limiting offered by firewalls but often inferior.
+	    Attacks that justify ignoring the
+	    contents of DNS responses are likely to be attacks on the
+	    DNS server itself.
+	    They usually should be discarded before the DNS server
+	    spends resources make TCP connections or parsing DNS requesets,
+	    but that rate limiting must be done before the
+	    DNS server sees the requests.
+	  </para>
+
+	  <para>
+	    The maximum size of the table used to track requests and
+	    rate limit responses is set with <command>max-table-size</command>.
+	    Each entry in the table is between 40 and 80 bytes.
+	    The table needs approximately as many entries as the number
+	    of requests received per second.
+	    The default is 20,000.
+	    To reduce the cold start of growing the table,
+	    <command>min-table-size</command> (default 500)
+	    can set the minimum table size.
+	    Enable <command>rate-limit</command> category logging to monitor
+	    expansions of the table and inform
+	    choices for the initial and maximum table size.
+	  </para>
+
+	  <para>
+	    Use <command>log-only yes</command> to test rate limiting parameters
+	    without actually dropping any requests.
+	  </para>
+
+	  <para>
+	    Responses dropped by rate limits are included in the
+	    <command>RateDropped</command> and <command>QryDropped</command>
+	    statistics.
+	    Responses that truncated by rate limits are included in
+	    <command>RateSlipped</command> and <command>RespTruncated</command>.
+	</sect3>
       </sect2>
 
       <sect2 id="server_statement_grammar">
@@ -14577,6 +14829,32 @@ HOST-127.EXAMPLE. MX 0 .
 		      </para>
 		    </entry>
 		  </row>
+		  <row rowsep="0">
+		    <entry colname="1">
+		      <para><command>RateDropped</command></para>
+		    </entry>
+		    <entry colname="2">
+		      <para><command></command></para>
+		    </entry>
+		    <entry colname="3">
+		      <para>
+			Responses dropped by rate limits.
+		      </para>
+		    </entry>
+		  </row>
+		  <row rowsep="0">
+		    <entry colname="1">
+		      <para><command>RateSlipped</command></para>
+		    </entry>
+		    <entry colname="2">
+		      <para><command></command></para>
+		    </entry>
+		    <entry colname="3">
+		      <para>
+			Responses truncated by rate limits.
+		      </para>
+		    </entry>
+		  </row>
 		</tbody>
               </tgroup>
             </informaltable>

lib/dns/Makefile.in

@@ -70,8 +70,8 @@ DNSOBJS =	acache.@O@ acl.@O@ adb.@O@ byaddr.@O@ \
 		portlist.@O@ private.@O@ \
 		rbt.@O@ rbtdb.@O@ rbtdb64.@O@ rcode.@O@ rdata.@O@ \
 		rdatalist.@O@ rdataset.@O@ rdatasetiter.@O@ rdataslab.@O@ \
-		request.@O@ resolver.@O@ result.@O@ rootns.@O@ rpz.@O@ \
+		request.@O@ resolver.@O@ result.@O@ rootns.@O@ \
-		rriterator.@O@ sdb.@O@ \
+		rpz.@O@ rrl.@O@ rriterator.@O@ sdb.@O@ \
 		sdlz.@O@ soa.@O@ ssu.@O@ ssu_external.@O@ \
 		stats.@O@ tcpmsg.@O@ time.@O@ timer.@O@ tkey.@O@ \
 		tsec.@O@ tsig.@O@ ttl.@O@ update.@O@ validator.@O@ \
@@ -98,7 +98,7 @@ DNSSRCS =	acache.c acl.c adb.c byaddr.c \
 		name.c ncache.c nsec.c nsec3.c order.c peer.c portlist.c \
 		rbt.c rbtdb.c rbtdb64.c rcode.c rdata.c rdatalist.c \
 		rdataset.c rdatasetiter.c rdataslab.c request.c \
-		resolver.c result.c rootns.c rpz.c rriterator.c \
+		resolver.c result.c rootns.c rpz.c rrl.c rriterator.c \
 		sdb.c sdlz.c soa.c ssu.c ssu_external.c \
 		stats.c tcpmsg.c time.c timer.c tkey.c \
 		tsec.c tsig.c ttl.c update.c validator.c \

lib/dns/include/dns/log.h

@@ -43,6 +43,7 @@ LIBDNS_EXTERNAL_DATA extern isc_logmodule_t dns_modules[];
 #define DNS_LOGCATEGORY_DELEGATION_ONLY	(&dns_categories[10])
 #define DNS_LOGCATEGORY_EDNS_DISABLED	(&dns_categories[11])
 #define DNS_LOGCATEGORY_RPZ		(&dns_categories[12])
+#define DNS_LOGCATEGORY_RRL		(&dns_categories[13])
 
 /* Backwards compatibility. */
 #define DNS_LOGCATEGORY_GENERAL		ISC_LOGCATEGORY_GENERAL

lib/dns/include/dns/rrl.h

@@ -0,0 +1,273 @@
+/*
+ * Copyright (C) 2012-2013  Internet Systems Consortium, Inc. ("ISC")
+ *
+ * Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC 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.
+ */
+
+
+#ifndef DNS_RRL_H
+#define DNS_RRL_H 1
+
+/*
+ * Rate limit DNS responses.
+ */
+
+#include <isc/lang.h>
+
+#include <dns/fixedname.h>
+#include <dns/rdata.h>
+#include <dns/types.h>
+
+ISC_LANG_BEGINDECLS
+
+
+/*
+ * Memory allocation or other failures.
+ */
+#define DNS_RRL_LOG_FAIL	ISC_LOG_WARNING
+/*
+ * dropped or slipped responses.
+ */
+#define DNS_RRL_LOG_DROP	ISC_LOG_INFO
+/*
+ * Major events in dropping or slipping.
+ */
+#define DNS_RRL_LOG_DEBUG1	ISC_LOG_DEBUG(3)
+/*
+ * Limit computations.
+ */
+#define DNS_RRL_LOG_DEBUG2	ISC_LOG_DEBUG(4)
+/*
+ * Even less interesting.
+ */
+#define DNS_RRL_LOG_DEBUG3	ISC_LOG_DEBUG(9)
+
+
+#define DNS_RRL_LOG_ERR_LEN	64
+#define DNS_RRL_LOG_BUF_LEN	(sizeof("would continue limiting") +	\
+				 DNS_RRL_LOG_ERR_LEN +			\
+				 sizeof(" responses to ") +		\
+				 ISC_NETADDR_FORMATSIZE +		\
+				 sizeof("/128 for IN ") +		\
+				 DNS_RDATATYPE_FORMATSIZE +		\
+				 DNS_NAME_FORMATSIZE)
+
+
+typedef struct dns_rrl_hash dns_rrl_hash_t;
+
+/*
+ * Response types.
+ */
+typedef enum {
+	DNS_RRL_RTYPE_FREE = 0,
+	DNS_RRL_RTYPE_QUERY,
+	DNS_RRL_RTYPE_DELEGATION,
+	DNS_RRL_RTYPE_NXDOMAIN,
+	DNS_RRL_RTYPE_ERROR,
+	DNS_RRL_RTYPE_ALL,
+	DNS_RRL_RTYPE_TCP,
+} dns_rrl_rtype_t;
+
+/*
+ * A rate limit bucket key.
+ * This should be small to limit the total size of the database.
+ * The hash of the qname should be wide enough to make the probability
+ * of collisions among requests from a single IP address block less than 50%.
+ * We need a 32-bit hash value for 10000 qps (e.g. random qnames forged
+ * by attacker) to collide with legitimate qnames from the target with
+ * probability at most 1%.
+ */
+#define DNS_RRL_MAX_PREFIX  64
+typedef union dns_rrl_key dns_rrl_key_t;
+union dns_rrl_key {
+	struct {
+		isc_uint32_t	    ip[DNS_RRL_MAX_PREFIX/32];
+		isc_uint32_t	    qname_hash;
+		dns_rdatatype_t	    qtype;
+		isc_uint8_t	    qclass;
+		dns_rrl_rtype_t	    rtype   :3;
+		isc_boolean_t	    ipv6    :1;
+	} s;
+	isc_uint16_t	w[1];
+};
+
+/*
+ * A rate-limit entry.
+ * This should be small to limit the total size of the table of entries.
+ */
+typedef struct dns_rrl_entry dns_rrl_entry_t;
+typedef ISC_LIST(dns_rrl_entry_t) dns_rrl_bin_t;
+struct dns_rrl_entry {
+	ISC_LINK(dns_rrl_entry_t) lru;
+	ISC_LINK(dns_rrl_entry_t) hlink;
+	dns_rrl_key_t	key;
+# define DNS_RRL_RESPONSE_BITS	24
+	signed int	responses   :DNS_RRL_RESPONSE_BITS;
+# define DNS_RRL_QNAMES_BITS	8
+	unsigned int	log_qname   :DNS_RRL_QNAMES_BITS;
+
+# define DNS_RRL_TS_GEN_BITS	2
+	unsigned int	ts_gen	    :DNS_RRL_TS_GEN_BITS;
+	isc_boolean_t	ts_valid    :1;
+# define DNS_RRL_HASH_GEN_BITS	1
+	unsigned int	hash_gen    :DNS_RRL_HASH_GEN_BITS;
+	isc_boolean_t	logged	    :1;
+# define DNS_RRL_LOG_BITS	11
+	unsigned int	log_secs    :DNS_RRL_LOG_BITS;
+
+# define DNS_RRL_TS_BITS	12
+	unsigned int	ts	    :DNS_RRL_TS_BITS;
+
+# define DNS_RRL_MAX_SLIP	10
+	unsigned int	slip_cnt    :4;
+};
+
+#define DNS_RRL_MAX_TIME_TRAVEL	5
+#define DNS_RRL_FOREVER		(1<<DNS_RRL_TS_BITS)
+#define DNS_RRL_MAX_TS		(DNS_RRL_FOREVER - 1)
+
+#define DNS_RRL_MAX_RESPONSES	((1<<(DNS_RRL_RESPONSE_BITS-1))-1)
+#define DNS_RRL_MAX_WINDOW	3600
+#if DNS_RRL_MAX_WINDOW >= DNS_RRL_MAX_TS
+#error "DNS_RRL_MAX_WINDOW is too large"
+#endif
+#define DNS_RRL_MAX_RATE	1000
+#if DNS_RRL_MAX_RATE >= (DNS_RRL_MAX_RESPONSES / DNS_RRL_MAX_WINDOW)
+#error "DNS_RRL_MAX_rate is too large"
+#endif
+
+#if (1<<DNS_RRL_LOG_BITS) >= DNS_RRL_FOREVER
+#error DNS_RRL_LOG_BITS is too big
+#endif
+#define DNS_RRL_MAX_LOG_SECS	1800
+#if DNS_RRL_MAX_LOG_SECS >= (1<<DNS_RRL_LOG_BITS)
+#error "DNS_RRL_MAX_LOG_SECS is too large"
+#endif
+#define DNS_RRL_STOP_LOG_SECS	60
+#if DNS_RRL_STOP_LOG_SECS >= (1<<DNS_RRL_LOG_BITS)
+#error "DNS_RRL_STOP_LOG_SECS is too large"
+#endif
+
+
+/*
+ * A hash table of rate-limit entries.
+ */
+struct dns_rrl_hash {
+	isc_stdtime_t	check_time;
+	unsigned int	gen	    :DNS_RRL_HASH_GEN_BITS;
+	int		length;
+	dns_rrl_bin_t	bins[1];
+};
+
+/*
+ * A block of rate-limit entries.
+ */
+typedef struct dns_rrl_block dns_rrl_block_t;
+struct dns_rrl_block {
+	ISC_LINK(dns_rrl_block_t) link;
+	int		size;
+	dns_rrl_entry_t	entries[1];
+};
+
+/*
+ * A rate limited qname buffer.
+ */
+typedef struct dns_rrl_qname_buf dns_rrl_qname_buf_t;
+struct dns_rrl_qname_buf {
+	ISC_LINK(dns_rrl_qname_buf_t) link;
+	const dns_rrl_entry_t *e;
+	unsigned int	    index;
+	dns_fixedname_t	    qname;
+};
+
+/*
+ * Per-view query rate limit parameters and a pointer to database.
+ */
+typedef struct dns_rrl dns_rrl_t;
+struct dns_rrl {
+	isc_mutex_t	lock;
+	isc_mem_t	*mctx;
+
+	isc_boolean_t	log_only;
+	int		responses_per_second;
+	int		errors_per_second;
+	int		nxdomains_per_second;
+	int		all_per_second;
+	int		window;
+	int		slip;
+	double		qps_scale;
+	int		max_entries;
+
+	dns_acl_t	*exempt;
+
+	int		num_entries;
+
+	int		qps_responses;
+	isc_stdtime_t	qps_time;
+	double		qps;
+	int		scaled_responses_per_second;
+	int		scaled_errors_per_second;
+	int		scaled_nxdomains_per_second;
+	int		scaled_all_per_second;
+	int		scaled_slip;
+
+	unsigned int	probes;
+	unsigned int	searches;
+
+	ISC_LIST(dns_rrl_block_t) blocks;
+	ISC_LIST(dns_rrl_entry_t) lru;
+
+	dns_rrl_hash_t	*hash;
+	dns_rrl_hash_t	*old_hash;
+	unsigned int	hash_gen;
+
+	unsigned int	ts_gen;
+# define DNS_RRL_TS_BASES   (1<<DNS_RRL_TS_GEN_BITS)
+	isc_stdtime_t	ts_bases[DNS_RRL_TS_BASES];
+
+	int		ipv4_prefixlen;
+	isc_uint32_t	ipv4_mask;
+	int		ipv6_prefixlen;
+	isc_uint32_t	ipv6_mask[4];
+
+	isc_stdtime_t	log_stops_time;
+	dns_rrl_entry_t	*last_logged;
+	int		num_logged;
+	int		num_qnames;
+	ISC_LIST(dns_rrl_qname_buf_t) qname_free;
+# define DNS_RRL_QNAMES	    (1<<DNS_RRL_QNAMES_BITS)
+	dns_rrl_qname_buf_t *qnames[DNS_RRL_QNAMES];
+};
+
+typedef enum {
+	DNS_RRL_RESULT_OK,
+	DNS_RRL_RESULT_DROP,
+	DNS_RRL_RESULT_SLIP,
+} dns_rrl_result_t;
+
+dns_rrl_result_t
+dns_rrl(dns_view_t *view,
+	const isc_sockaddr_t *client_addr, isc_boolean_t is_tcp,
+	dns_rdataclass_t rdclass, dns_rdatatype_t qtype,
+	dns_name_t *qname, isc_result_t resp_result, isc_stdtime_t now,
+	isc_boolean_t wouldlog, char *log_buf, unsigned int log_buf_len);
+
+void
+dns_rrl_view_destroy(dns_view_t *view);
+
+isc_result_t
+dns_rrl_init(dns_rrl_t **rrlp, dns_view_t *view, int min_entries);
+
+ISC_LANG_ENDDECLS
+
+#endif /* DNS_RRL_H */

lib/dns/include/dns/view.h

@@ -74,6 +74,7 @@
 #include <dns/acl.h>
 #include <dns/clientinfo.h>
 #include <dns/fixedname.h>
+#include <dns/rrl.h>
 #include <dns/rdatastruct.h>
 #include <dns/rpz.h>
 #include <dns/types.h>
@@ -143,6 +144,7 @@ struct dns_view {
 	dns_rbt_t *			answeracl_exclude;
 	dns_rbt_t *			denyanswernames;
 	dns_rbt_t *			answernames_exclude;
+	dns_rrl_t *			rrl;
 	isc_boolean_t			provideixfr;
 	isc_boolean_t			requestnsid;
 	dns_ttl_t			maxcachettl;

lib/dns/log.c

@@ -45,6 +45,7 @@ LIBDNS_EXTERNAL_DATA isc_logcategory_t dns_categories[] = {
 	{ "delegation-only", 0 },
 	{ "edns-disabled", 0 },
 	{ "rpz",	0 },
+	{ "rate-limit",	0 },
 	{ NULL, 	0 }
 };
 

lib/dns/view.c

@@ -49,6 +49,7 @@
 #include <dns/masterdump.h>
 #include <dns/order.h>
 #include <dns/peer.h>
+#include <dns/rrl.h>
 #include <dns/rbt.h>
 #include <dns/rdataset.h>
 #include <dns/request.h>
@@ -184,6 +185,7 @@ dns_view_create(isc_mem_t *mctx, dns_rdataclass_t rdclass,
 	view->answeracl_exclude = NULL;
 	view->denyanswernames = NULL;
 	view->answernames_exclude = NULL;
+	view->rrl = NULL;
 	view->provideixfr = ISC_TRUE;
 	view->maxcachettl = 7 * 24 * 3600;
 	view->maxncachettl = 3 * 3600;
@@ -336,6 +338,8 @@ destroy(dns_view_t *view) {
 		dns_acache_detach(&view->acache);
 	}
 	dns_rpz_view_destroy(view);
+	dns_rrl_view_destroy(view);
+
 	for (dlzdb = ISC_LIST_HEAD(view->dlz_searched);
 	     dlzdb != NULL;
 	     dlzdb = ISC_LIST_HEAD(view->dlz_searched)) {
@@ -353,6 +357,7 @@ destroy(dns_view_t *view) {
 	INSIST(ISC_LIST_EMPTY(view->rpz_zones));
 	INSIST(ISC_LIST_EMPTY(view->dlz_searched));
 	INSIST(ISC_LIST_EMPTY(view->dlz_unsearched));
+	INSIST(view->rrl == NULL);
 #endif
 	if (view->requestmgr != NULL)
 		dns_requestmgr_detach(&view->requestmgr);

lib/dns/win32/libdns.def

@@ -667,6 +667,9 @@ dns_rriterator_init
 dns_rriterator_next
 dns_rriterator_nextrrset
 dns_rriterator_pause
+dns_rrl
+dns_rrl_init
+dns_rrl_view_destroy
 dns_sdb_putnamedrr
 dns_sdb_putrdata
 dns_sdb_putrr

lib/dns/win32/libdns.dsp

@@ -346,6 +346,10 @@ SOURCE=..\include\dns\rpz.h
 # End Source File
 # Begin Source File
 
+SOURCE=..\include\dns\rrl.h
+# End Source File
+# Begin Source File
+
 SOURCE=..\include\dns\rriterator.h
 # End Source File
 # Begin Source File
@@ -650,6 +654,10 @@ SOURCE=..\rpz.c
 # End Source File
 # Begin Source File
 
+SOURCE=..\rrl.c
+# End Source File
+# Begin Source File
+
 SOURCE=..\rriterator.c
 # End Source File
 # Begin Source File

lib/dns/win32/libdns.mak

@@ -184,6 +184,7 @@ CLEAN :
 	-@erase "$(INTDIR)\result.obj"
 	-@erase "$(INTDIR)\rootns.obj"
 	-@erase "$(INTDIR)\rpz.obj"
+	-@erase "$(INTDIR)\rrl.obj"
 	-@erase "$(INTDIR)\sdb.obj"
 	-@erase "$(INTDIR)\sdlz.obj"
 	-@erase "$(INTDIR)\soa.obj"
@@ -309,6 +310,7 @@ LINK32_OBJS= \
 	"$(INTDIR)\result.obj" \
 	"$(INTDIR)\rootns.obj" \
 	"$(INTDIR)\rpz.obj" \
+	"$(INTDIR)\rrl.obj" \
 	"$(INTDIR)\rriterator.obj" \
 	"$(INTDIR)\sdb.obj" \
 	"$(INTDIR)\sdlz.obj" \
@@ -505,6 +507,8 @@ CLEAN :
 	-@erase "$(INTDIR)\rootns.sbr"
 	-@erase "$(INTDIR)\rpz.obj"
 	-@erase "$(INTDIR)\rpz.sbr"
+	-@erase "$(INTDIR)\rrl.obj"
+	-@erase "$(INTDIR)\rrl.sbr"
 	-@erase "$(INTDIR)\rriterator.obj"
 	-@erase "$(INTDIR)\rriterator.sbr"
 	-@erase "$(INTDIR)\sdb.obj"
@@ -651,6 +655,7 @@ BSC32_SBRS= \
 	"$(INTDIR)\result.sbr" \
 	"$(INTDIR)\rootns.sbr" \
 	"$(INTDIR)\rpz.sbr" \
+	"$(INTDIR)\rrl.sbr" \
 	"$(INTDIR)\rriterator.sbr" \
 	"$(INTDIR)\sdb.sbr" \
 	"$(INTDIR)\sdlz.sbr" \
@@ -748,6 +753,7 @@ LINK32_OBJS= \
 	"$(INTDIR)\result.obj" \
 	"$(INTDIR)\rootns.obj" \
 	"$(INTDIR)\rpz.obj" \
+	"$(INTDIR)\rrl.obj" \
 	"$(INTDIR)\rriterator.obj" \
 	"$(INTDIR)\sdb.obj" \
 	"$(INTDIR)\sdlz.obj" \
@@ -1724,6 +1730,24 @@ SOURCE=..\rpz.c
 	$(CPP) $(CPP_PROJ) $(SOURCE)
 
 
+!ENDIF 
+
+SOURCE=..\rrl.c
+
+!IF  "$(CFG)" == "libdns - Win32 Release"
+
+
+"$(INTDIR)\rrl.obj" : $(SOURCE) "$(INTDIR)"
+	$(CPP) $(CPP_PROJ) $(SOURCE)
+
+
+!ELSEIF  "$(CFG)" == "libdns - Win32 Debug"
+
+
+"$(INTDIR)\rrl.obj"	"$(INTDIR)\rrl.sbr" : $(SOURCE) "$(INTDIR)"
+	$(CPP) $(CPP_PROJ) $(SOURCE)
+
+
 !ENDIF 
 
 SOURCE=..\rriterator.c

lib/isccfg/namedconf.c

@@ -1259,6 +1259,39 @@ static cfg_type_t cfg_type_rpz = {
 };
 
 
+/*
+ * rate-limit
+ */
+static cfg_clausedef_t rrl_clauses[] = {
+	{ "responses-per-second", &cfg_type_uint32, 0 },
+	{ "errors-per-second", &cfg_type_uint32, 0 },
+	{ "nxdomains-per-second", &cfg_type_uint32, 0 },
+	{ "responses-per-second", &cfg_type_uint32, 0 },
+	{ "all-per-second", &cfg_type_uint32, 0 },
+	{ "slip", &cfg_type_uint32, 0 },
+	{ "window", &cfg_type_uint32, 0 },
+	{ "log-only", &cfg_type_boolean, 0 },
+	{ "qps-scale", &cfg_type_uint32, 0 },
+	{ "IPv4-prefix-length", &cfg_type_uint32, 0 },
+	{ "IPv6-prefix-length", &cfg_type_uint32, 0 },
+	{ "exempt-clients", &cfg_type_bracketed_aml, 0 },
+	{ "max-table-size", &cfg_type_uint32, 0 },
+	{ "min-table-size", &cfg_type_uint32, 0 },
+	{ NULL, NULL, 0 }
+};
+
+static cfg_clausedef_t *rrl_clausesets[] = {
+	rrl_clauses,
+	NULL
+};
+
+static cfg_type_t cfg_type_rrl = {
+	"rate-limit", cfg_parse_map, cfg_print_map, cfg_doc_map,
+	&cfg_rep_map, rrl_clausesets
+};
+
+
+
 /*%
  * dnssec-lookaside
  */
@@ -1417,6 +1450,7 @@ view_clauses[] = {
 	   CFG_CLAUSEFLAG_NOTCONFIGURED },
 #endif
 	{ "response-policy", &cfg_type_rpz, 0 },
+	{ "rate-limit", &cfg_type_rrl, 0 },
 	{ NULL, NULL, 0 }
 };