Merge pull request #819 from pavel-odintsov/pavel/suppress_a

wcawijngaards · web-flow · commit 6a4a9435d103 · 2023-01-20T16:18:05.000+01:00
Added new static zone type block_a to suppress all A queries for specific zones
diff --git a/doc/example.conf.in b/doc/example.conf.in
@@ -814,6 +814,8 @@ server:
 	# o always_transparent, always_refuse, always_nxdomain, always_nodata,
 	#   always_deny resolve in that way but ignore local data for
 	#   that name
+	# o block_a resolves all records normally but returns
+	#   NODATA for A queries and ignores local data for that name
 	# o always_null returns 0.0.0.0 or ::0 for any name in the zone.
 	# o noview breaks out of that view towards global local-zones.
 	#
diff --git a/doc/unbound.conf.5.in b/doc/unbound.conf.5.in
@@ -1398,10 +1398,10 @@ address space are not validated.  This is usually required whenever
 Configure a local zone. The type determines the answer to give if
 there is no match from local\-data. The types are deny, refuse, static,
 transparent, redirect, nodefault, typetransparent, inform, inform_deny,
-inform_redirect, always_transparent, always_refuse, always_nxdomain, always_null, noview,
-and are explained below. After that the default settings are listed. Use
-local\-data: to enter data into the local zone. Answers for local zones
-are authoritative DNS answers. By default the zones are class IN.
+inform_redirect, always_transparent, block_a, always_refuse, always_nxdomain,
+always_null, noview, and are explained below. After that the default settings
+are listed. Use local\-data: to enter data into the local zone. Answers for
+local zones are authoritative DNS answers. By default the zones are class IN.
 .IP
 If you need more complicated authoritative data, with referrals, wildcards,
 CNAME/DNAME support, or DNSSEC authoritative service, setup a stub\-zone for
@@ -1476,6 +1476,12 @@ Ie. answer queries with fixed data and also log the machines that ask.
 \h'5'\fIalways_transparent\fR
 Like transparent, but ignores local data and resolves normally.
 .TP 10
+\h'5'\fIblock_a\fR
+Like transparent, but ignores local data and resolves normally all query
+types excluding A. For A queries it unconditionally returns NODATA.
+Useful in cases when there is a need to explicitly force all apps to use
+IPv6 protocol and avoid any queries to IPv4.
+.TP 10
 \h'5'\fIalways_refuse\fR
 Like refuse, but ignores local data and refuses the query.
 .TP 10
diff --git a/services/localzone.c b/services/localzone.c
@@ -1603,7 +1603,7 @@ local_zone_does_not_cover(struct local_zone* z, struct query_info* qinfo,
 	struct local_data key;
 	struct local_data* ld = NULL;
 	struct local_rrset* lr = NULL;
-	if(z->type == local_zone_always_transparent)
+	if(z->type == local_zone_always_transparent || z->type == local_zone_block_a)
 		return 1;
 	if(z->type != local_zone_transparent
 		&& z->type != local_zone_typetransparent
@@ -1679,6 +1679,16 @@ local_zones_zone_answer(struct local_zone* z, struct module_env* env,
 	} else if(lz_type == local_zone_typetransparent
 		|| lz_type == local_zone_always_transparent) {
 		/* no NODATA or NXDOMAINS for this zone type */
+		return 0;
+	} else if(lz_type == local_zone_block_a) {
+		// Return NODATA for all A queries
+		if(qinfo->qtype == LDNS_RR_TYPE_A) {
+			local_error_encode(qinfo, env, edns, repinfo, buf, temp,
+				LDNS_RCODE_NOERROR, (LDNS_RCODE_NOERROR|BIT_AA),
+				LDNS_EDE_NONE, NULL);
+				return 1;
+		}
+
 		return 0;
 	} else if(lz_type == local_zone_always_null) {
 		/* 0.0.0.0 or ::0 or noerror/nodata for this zone type,
@@ -1846,7 +1856,8 @@ local_zones_answer(struct local_zones* zones, struct module_env* env,
 		if(z && (lzt == local_zone_transparent ||
 			lzt == local_zone_typetransparent ||
 			lzt == local_zone_inform ||
-			lzt == local_zone_always_transparent) &&
+			lzt == local_zone_always_transparent ||
+			lzt == local_zone_block_a) &&
 			local_zone_does_not_cover(z, qinfo, labs)) {
 			lock_rw_unlock(&z->lock);
 			z = NULL;
@@ -1894,6 +1905,7 @@ local_zones_answer(struct local_zones* zones, struct module_env* env,
 
 	if(lzt != local_zone_always_refuse
 		&& lzt != local_zone_always_transparent
+		&& lzt != local_zone_block_a
 		&& lzt != local_zone_always_nxdomain
 		&& lzt != local_zone_always_nodata
 		&& lzt != local_zone_always_deny
@@ -1924,6 +1936,7 @@ const char* local_zone_type2str(enum localzone_type t)
 		case local_zone_inform_deny: return "inform_deny";
 		case local_zone_inform_redirect: return "inform_redirect";
 		case local_zone_always_transparent: return "always_transparent";
+		case local_zone_block_a: return "block_a";
 		case local_zone_always_refuse: return "always_refuse";
 		case local_zone_always_nxdomain: return "always_nxdomain";
 		case local_zone_always_nodata: return "always_nodata";
@@ -1958,6 +1971,8 @@ int local_zone_str2type(const char* type, enum localzone_type* t)
 		*t = local_zone_inform_redirect;
 	else if(strcmp(type, "always_transparent") == 0)
 		*t = local_zone_always_transparent;
+	else if(strcmp(type, "block_a") == 0)
+		*t = local_zone_block_a;
 	else if(strcmp(type, "always_refuse") == 0)
 		*t = local_zone_always_refuse;
 	else if(strcmp(type, "always_nxdomain") == 0)
diff --git a/services/localzone.h b/services/localzone.h
@@ -88,6 +88,8 @@ enum localzone_type {
 	local_zone_inform_redirect,
 	/** resolve normally, even when there is local data */	
 	local_zone_always_transparent,
+	/** resolve normally, even when there is local data but return NODATA for A queries */
+	local_zone_block_a,
 	/** answer with error, even when there is local data */	
 	local_zone_always_refuse,
 	/** answer with nxdomain, even when there is local data */
diff --git a/util/configparser.y b/util/configparser.y
@@ -2218,6 +2218,7 @@ server_local_zone: VAR_LOCAL_ZONE STRING_ARG STRING_ARG
 		   strcmp($3, "transparent")!=0 && strcmp($3, "nodefault")!=0
 		   && strcmp($3, "typetransparent")!=0
 		   && strcmp($3, "always_transparent")!=0
+		   && strcmp($3, "block_a")!=0
 		   && strcmp($3, "always_refuse")!=0
 		   && strcmp($3, "always_nxdomain")!=0
 		   && strcmp($3, "always_nodata")!=0
@@ -2230,7 +2231,7 @@ server_local_zone: VAR_LOCAL_ZONE STRING_ARG STRING_ARG
 			yyerror("local-zone type: expected static, deny, "
 				"refuse, redirect, transparent, "
 				"typetransparent, inform, inform_deny, "
-				"inform_redirect, always_transparent, "
+				"inform_redirect, always_transparent, block_a,"
 				"always_refuse, always_nxdomain, "
 				"always_nodata, always_deny, always_null, "
 				"noview, nodefault or ipset");

Original file line number	Diff line number	Diff line change
`@@ -814,6 +814,8 @@ server:`
`814`	`814`	`# o always_transparent, always_refuse, always_nxdomain, always_nodata,`
`815`	`815`	`# always_deny resolve in that way but ignore local data for`
`816`	`816`	`# that name`
	`817`	`+ # o block_a resolves all records normally but returns`
	`818`	`+ # NODATA for A queries and ignores local data for that name`
`817`	`819`	`# o always_null returns 0.0.0.0 or ::0 for any name in the zone.`
`818`	`820`	`# o noview breaks out of that view towards global local-zones.`
`819`	`821`	`#`