1432. [func] The advertised EDNS UDP buffer size can now be set

                        via named.conf (edns-udp-size).
developer: marka
reviewer: explorer

CHANGES

+1432.	[func]		The advertised EDNS UDP buffer size can now be set
+			via named.conf (edns-udp-size).
+
 1431.	[bug]		isc_print_snprintf() "%s" with precision could walk of
 			end of arguement. [RT #5191]
 

bin/named/client.c

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: client.c,v 1.214 2003/01/21 06:11:45 marka Exp $ */
+/* $Id: client.c,v 1.215 2003/02/26 02:03:57 marka Exp $ */
 
 #include <config.h>
 
@@ -34,6 +34,7 @@
 #include <dns/events.h>
 #include <dns/message.h>
 #include <dns/rcode.h>
+#include <dns/resolver.h>
 #include <dns/rdata.h>
 #include <dns/rdataclass.h>
 #include <dns/rdatalist.h>
@@ -1028,6 +1029,9 @@ client_addopt(ns_client_t *client) {
 	dns_rdatalist_t *rdatalist;
 	dns_rdata_t *rdata;
 	isc_result_t result;
+	dns_view_t *view;
+	dns_resolver_t *resolver;
+	isc_uint16_t udpsize;
 
 	REQUIRE(client->opt == NULL);	/* XXXRTH free old. */
 
@@ -1051,7 +1055,13 @@ client_addopt(ns_client_t *client) {
 	/*
 	 * Set the maximum UDP buffer size.
 	 */
-	rdatalist->rdclass = RECV_BUFFER_SIZE;
+	view = client->view;
+	resolver = (view != NULL) ? view->resolver : NULL;
+	if (resolver != NULL)
+		udpsize = dns_resolver_getudpsize(resolver);
+	else
+		udpsize = ns_g_udpsize;
+	rdatalist->rdclass = udpsize;
 
 	/*
 	 * Set EXTENDED-RCODE, VERSION and Z to 0.

bin/named/config.c

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: config.c,v 1.37 2003/02/04 06:10:08 marka Exp $ */
+/* $Id: config.c,v 1.38 2003/02/26 02:03:57 marka Exp $ */
 
 #include <config.h>
 
@@ -91,6 +91,7 @@ options {\n\
 	treat-cr-as-space true;\n\
 	use-id-pool true;\n\
 	use-ixfr true;\n\
+	edns-udp-size 4096;\n\
 \n\
 	/* view */\n\
 	allow-notify {none;};\n\

bin/named/include/named/globals.h

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: globals.h,v 1.60 2002/11/12 23:38:11 explorer Exp $ */
+/* $Id: globals.h,v 1.61 2003/02/26 02:03:58 marka Exp $ */
 
 #ifndef NAMED_GLOBALS_H
 #define NAMED_GLOBALS_H 1
@@ -84,6 +84,7 @@ EXTERN const char *		lwresd_g_resolvconffile	INIT("/etc"
 							     "/resolv.conf");
 EXTERN isc_boolean_t		ns_g_conffileset	INIT(ISC_FALSE);
 EXTERN isc_boolean_t		lwresd_g_useresolvconf	INIT(ISC_FALSE);
+EXTERN isc_uint16_t		ns_g_udpsize		INIT(4096);
 
 /*
  * Initial resource limits.

bin/named/server.c

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: server.c,v 1.394 2003/01/20 23:51:23 marka Exp $ */
+/* $Id: server.c,v 1.395 2003/02/26 02:03:58 marka Exp $ */
 
 #include <config.h>
 
@@ -581,6 +581,7 @@ configure_view(dns_view_t *view, cfg_obj_t *config, cfg_obj_t *vconfig,
 	int i;
 	char *str;
 	dns_order_t *order = NULL;
+	isc_uint32_t udpsize;
 
 	REQUIRE(DNS_VIEW_VALID(view));
 
@@ -741,6 +742,19 @@ configure_view(dns_view_t *view, cfg_obj_t *config, cfg_obj_t *vconfig,
 		lame_ttl = 1800;
 	dns_resolver_setlamettl(view->resolver, lame_ttl);
 	
+	/*
+	 * Set the resolver's EDNS UDP size.
+	 */
+	obj = NULL;
+	result = ns_config_get(maps, "edns-udp-size", &obj);
+	INSIST(result == ISC_R_SUCCESS);
+	udpsize = cfg_obj_asuint32(obj);
+	if (udpsize < 512)
+		udpsize = 512;
+	if (udpsize > 4096)
+		udpsize = 4096;
+	dns_resolver_setudpsize(view->resolver, udpsize);
+
 	/*
 	 * A global or view "forwarders" option, if present,
 	 * creates an entry for "." in the forwarding table.
@@ -1756,6 +1770,7 @@ load_configuration(const char *filename, ns_server_t *server,
 	dns_dispatch_t *dispatchv6 = NULL;
 	isc_uint32_t interface_interval;
 	isc_uint32_t heartbeat_interval;
+	isc_uint32_t udpsize;
 	in_port_t listen_port;
 	int i;
 
@@ -1856,6 +1871,19 @@ load_configuration(const char *filename, ns_server_t *server,
 	INSIST(result == ISC_R_SUCCESS);
 	server->aclenv.match_mapped = cfg_obj_asboolean(obj);
 
+	/*
+	 * Set the EDNS UDP size when we don't match a view.
+	 */
+	obj = NULL;
+	result = ns_config_get(maps, "edns-udp-size", &obj);
+	INSIST(result == ISC_R_SUCCESS);
+	udpsize = cfg_obj_asuint32(obj);
+	if (udpsize < 512)
+		udpsize = 512;
+	if (udpsize > 4096)
+		udpsize = 4096;
+	ns_g_udpsize = udpsize;
+
 	/*
 	 * Configure the zone manager.
 	 */

doc/arm/Bv9ARM-book.xml

@@ -2,7 +2,7 @@
 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.0//EN"
                "http://www.oasis-open.org/docbook/xml/4.0/docbookx.dtd">
 
-<!-- File: $Id: Bv9ARM-book.xml,v 1.214 2003/02/07 01:13:11 marka Exp $ -->
+<!-- File: $Id: Bv9ARM-book.xml,v 1.215 2003/02/26 02:03:58 marka Exp $ -->
 
 <book>
 <title>BIND 9 Administrator Reference Manual</title>
@@ -2782,6 +2782,7 @@ statement in the <filename>named.conf</filename> file:</para>
     <optional> max-cache-size <replaceable>size_spec</replaceable> ; </optional>
     <optional> match-mapped-addresses <replaceable>yes_or_no</replaceable>; </optional>
     <optional> preferred-glue ( <replaceable>A</replaceable> | <replaceable>AAAA</replaceable> | <replaceable>NONE</replaceable> ); </optional>
+    <optional> edns-udp-size <replaceable>number</replaceable>; </optional>
 };
 </programlisting>
 </sect2>
@@ -4014,6 +4015,16 @@ These options are valid for slave and stub zones,
 and clamp the SOA refresh and retry times to the specified values.
 </para></listitem></varlistentry>
 
+<varlistentry>
+<term><command>edns-udp-size</command></term>
+<listitem><para>
+<command>edns-udp-size</command> sets the advertised EDNS UDP buffer
+size.  Valid values are 512 to 4096 (values outside this range will be
+silently adjusted).  The default value is 4096.  The usual reason for
+setting edns-udp-size to a non default value it to get UDP answers to
+pass through broken firewalls that block fragmented packets and/or
+block UDP packets that are greater than 512 bytes.
+</para></listitem></varlistentry>
 </variablelist>
 
 </sect3>

lib/dns/include/dns/resolver.h

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: resolver.h,v 1.36 2003/01/16 03:59:25 marka Exp $ */
+/* $Id: resolver.h,v 1.37 2003/02/26 02:03:59 marka Exp $ */
 
 #ifndef DNS_RESOLVER_H
 #define DNS_RESOLVER_H 1
@@ -371,6 +371,18 @@ dns_resolver_addalternate(dns_resolver_t *resolver, isc_sockaddr_t *alt,
  * 	only one of 'name' or 'alt' to be valid.
  */
 
+void
+dns_resolver_setudpsize(dns_resolver_t *resolver, isc_uint16_t udpsize);
+/*
+ * Set the EDNS UDP buffer size advertised by the server.
+ */
+
+isc_uint16_t
+dns_resolver_getudpsize(dns_resolver_t *resolver);
+/*
+ * Get the current EDNS UDP buffer size.
+ */
+
 ISC_LANG_ENDDECLS
 
 #endif /* DNS_RESOLVER_H */

lib/dns/resolver.c

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: resolver.c,v 1.260 2003/01/18 03:18:30 marka Exp $ */
+/* $Id: resolver.c,v 1.261 2003/02/26 02:03:59 marka Exp $ */
 
 #include <config.h>
 
@@ -93,7 +93,7 @@
 /*
  * Maximum EDNS0 input packet size.
  */
-#define SEND_BUFFER_SIZE		2048		/* XXXRTH  Constant. */
+#define RECV_BUFFER_SIZE		4096		/* XXXRTH  Constant. */
 
 /*
  * This defines the maximum number of timeouts we will permit before we
@@ -284,6 +284,7 @@ struct dns_resolver {
 	fctxbucket_t *			buckets;
 	isc_uint32_t			lame_ttl;
 	ISC_LIST(alternate_t)		alternates;
+	isc_uint16_t			udpsize;
 	/* Locked by lock. */
 	unsigned int			references;
 	isc_boolean_t			exiting;
@@ -706,7 +707,7 @@ resquery_senddone(isc_task_t *task, isc_event_t *event) {
 }
 
 static inline isc_result_t
-fctx_addopt(dns_message_t *message) {
+fctx_addopt(dns_message_t *message, dns_resolver_t *res) {
 	dns_rdataset_t *rdataset;
 	dns_rdatalist_t *rdatalist;
 	dns_rdata_t *rdata;
@@ -732,7 +733,7 @@ fctx_addopt(dns_message_t *message) {
 	/*
 	 * Set Maximum UDP buffer size.
 	 */
-	rdatalist->rdclass = SEND_BUFFER_SIZE;
+	rdatalist->rdclass = res->udpsize;
 
 	/*
 	 * Set EXTENDED-RCODE, VERSION, and Z to 0, and the DO bit to 1.
@@ -1078,7 +1079,7 @@ resquery_send(resquery_t *query) {
 
 	if ((query->options & DNS_FETCHOPT_NOEDNS0) == 0) {
 		if ((query->addrinfo->flags & DNS_FETCHOPT_NOEDNS0) == 0) {
-			result = fctx_addopt(fctx->qmessage);
+			result = fctx_addopt(fctx->qmessage, res);
 			if (result != ISC_R_SUCCESS) {
 				/*
 				 * We couldn't add the OPT, but we'll press on.
@@ -5281,6 +5282,7 @@ dns_resolver_create(dns_view_t *view,
 	res->options = options;
 	res->lame_ttl = 0;
 	ISC_LIST_INIT(res->alternates);
+	res->udpsize = RECV_BUFFER_SIZE;
 
 	res->nbuckets = ntasks;
 	res->activebuckets = ntasks;
@@ -5925,3 +5927,15 @@ dns_resolver_addalternate(dns_resolver_t *resolver, isc_sockaddr_t *alt,
 
 	return (ISC_R_SUCCESS);
 }
+
+void
+dns_resolver_setudpsize(dns_resolver_t *resolver, isc_uint16_t udpsize) {
+	REQUIRE(VALID_RESOLVER(resolver));
+	resolver->udpsize = udpsize;
+}
+
+isc_uint16_t
+dns_resolver_getudpsize(dns_resolver_t *resolver) {
+	REQUIRE(VALID_RESOLVER(resolver));
+	return (resolver->udpsize);
+}

lib/isccfg/namedconf.c

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: namedconf.c,v 1.15 2003/02/04 06:10:09 marka Exp $ */
+/* $Id: namedconf.c,v 1.16 2003/02/26 02:04:00 marka Exp $ */
 
 #include <config.h>
 
@@ -607,6 +607,7 @@ view_clauses[] = {
 	{ "suppress-initial-notify", &cfg_type_boolean, CFG_CLAUSEFLAG_NYI },
 	{ "preferred-glue", &cfg_type_astring, 0 },
 	{ "dual-stack-servers", &cfg_type_nameportiplist, 0 },
+	{ "edns-udp-size", &cfg_type_uint32, 0 },
 	{ NULL, NULL, 0 }
 };