From: Vladimír Čunát <vladimir.cunat@nic.cz>
Date: Thu, 21 Aug 2025 12:26:09 +0000 (+0200)
Subject: fallback: allow to disable in views:
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=bdaaf20061e5c7987c7f33b6fd031956c5fcc1bc;p=thirdparty%2Fknot-resolver.git

fallback: allow to disable in views:

Including config and docs for this.
---

diff --git a/daemon/lua/kres-gen-33.lua b/daemon/lua/kres-gen-33.lua
index 6a5482884..bae7c9f6e 100644
--- a/daemon/lua/kres-gen-33.lua
+++ b/daemon/lua/kres-gen-33.lua
@@ -142,6 +142,7 @@ struct kr_qflags {
 	_Bool PKT_IS_SANE : 1;
 	_Bool DNS64_DISABLE : 1;
 	_Bool PASSTHRU_LEGACY : 1;
+	_Bool FALLBACK_DISABLE : 1;
 };
 typedef struct ranked_rr_array_entry {
 	uint32_t qry_uid;
diff --git a/doc/user/config-views.rst b/doc/user/config-views.rst
index f8de1fe2a..b9e46c51d 100644
--- a/doc/user/config-views.rst
+++ b/doc/user/config-views.rst
@@ -92,10 +92,15 @@ Actions
       .. option:: minimize: true|false
 
          Send minimum amount of information in recursive queries to enhance privacy.
+         Enabled by default.
 
       .. option:: dns64: true|false
 
-         Enable/disable DNS64.
+         Disable DNS64 if enabled globally.
+
+      .. option:: fallback: true|false
+
+         Disable fallback on resolution failure, if enabled globally.
 
       .. option:: price-factor: <float>
 
diff --git a/lib/rplan.h b/lib/rplan.h
index 16dffd2d4..779d6d250 100644
--- a/lib/rplan.h
+++ b/lib/rplan.h
@@ -59,6 +59,7 @@ struct kr_qflags {
 				  * some basic aspects of the packet are OK, e.g. QNAME. */
 	bool DNS64_DISABLE : 1;  /**< Don't do any DNS64 stuff (meant for view:addr). */
 	bool PASSTHRU_LEGACY : 1;/**< Ignore local-data overrides/blocks for this kr_request. */
+	bool FALLBACK_DISABLE : 1;/**< Don't attempt fallback.  Meant for views.  */
 };
 
 /** Combine flags together.  This means set union for simple flags. */
diff --git a/modules/fallback/fallback.lua b/modules/fallback/fallback.lua
index 5d445ba93..09112862d 100644
--- a/modules/fallback/fallback.lua
+++ b/modules/fallback/fallback.lua
@@ -33,11 +33,12 @@ M.layer.produce = function (state, req, pkt)
 	if not M.data_src or state == kres.FAIL or state == kres.DONE then return state end
 
 	local qry = req:current()
+	if qry.flags.FALLBACK_DISABLE then return state end
+
 	-- Don't do anything for priming, prefetching, etc.
 	-- TODO: not all cases detected ATM.
 	if qry.flags.NO_CACHE then return state end
 
-	-- FIXME: also check the source of traffic
 	local now = ffi.C.kr_now()
 	local deadline = qry.creation_time_mono + M.timeout
 	if now > deadline or qry.flags.NO_NS_FOUND then
diff --git a/python/knot_resolver/datamodel/templates/macros/view_macros.lua.j2 b/python/knot_resolver/datamodel/templates/macros/view_macros.lua.j2
index 2f1a79646..c727eb2be 100644
--- a/python/knot_resolver/datamodel/templates/macros/view_macros.lua.j2
+++ b/python/knot_resolver/datamodel/templates/macros/view_macros.lua.j2
@@ -12,6 +12,9 @@
 {% if not options.dns64 -%}
 "DNS64_DISABLE",
 {%- endif %}
+{% if not options.fallback -%}
+"FALLBACK_DISABLE",
+{%- endif %}
 {%- endmacro %}
 
 {% macro view_answer(answer) -%}
diff --git a/python/knot_resolver/datamodel/view_schema.py b/python/knot_resolver/datamodel/view_schema.py
index 6d94b02af..fc9de6c74 100644
--- a/python/knot_resolver/datamodel/view_schema.py
+++ b/python/knot_resolver/datamodel/view_schema.py
@@ -12,11 +12,13 @@ class ViewOptionsSchema(ConfigSchema):
     minimize: Send minimum amount of information in recursive queries to enhance privacy.
     dns64: Enable/disable DNS64.
     price_factor: Multiplies rate-limiting and defer prices of operations, use 0 to whitelist.
+    fallback: Enable/disable fallback on resolution failure.
     """
 
     minimize: bool = True
     dns64: bool = True
     price_factor: FloatNonNegative = FloatNonNegative(1.0)
+    fallback: bool = True
 
 
 class ViewSchema(ConfigSchema):