From ca184670a2d36262c704bdd79a5ebf05e3a47161 Mon Sep 17 00:00:00 2001
From: Mark Andrews <marka@isc.org>
Date: Tue, 24 Sep 2024 17:02:38 +1000
Subject: [PATCH] Add grease controls to the view structure

---
 lib/dns/include/dns/message.h |  3 ++-
 lib/dns/include/dns/view.h    | 14 ++++++++++++++
 lib/dns/view.c                |  1 +
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/lib/dns/include/dns/message.h b/lib/dns/include/dns/message.h
index a467ea447f..6c80694e5e 100644
--- a/lib/dns/include/dns/message.h
+++ b/lib/dns/include/dns/message.h
@@ -99,7 +99,8 @@
 #define DNS_MESSAGEFLAG_CD 0x0010U
 
 /*%< EDNS0 extended message flags */
-#define DNS_MESSAGEEXTFLAG_DO 0x8000U
+#define DNS_MESSAGEEXTFLAG_DO	       0x8000U
+#define DNS_MESSAGEEXTFLAG_KNOWN_FLAGS DNS_MESSAGEEXTFLAG_DO
 
 /*%< EDNS0 extended OPT codes */
 
diff --git a/lib/dns/include/dns/view.h b/lib/dns/include/dns/view.h
index 266ba49d6c..9dd2f0041d 100644
--- a/lib/dns/include/dns/view.h
+++ b/lib/dns/include/dns/view.h
@@ -186,6 +186,20 @@ struct dns_view {
 	uint16_t	      max_queries;
 	uint8_t		      max_restarts;
 
+	/*
+	 * Grease the protocol by sending possible future
+	 * changes and checking the result matches defined
+	 * behaviour.
+	 */
+	bool	     grease_dns_flags;	      /* DNS flag 0x40 */
+	bool	     grease_edns_flags;	      /* EDNS Unknown flags */
+	bool	     grease_edns_neg;	      /* EDNS version negotiation */
+	bool	     grease_nsid;	      /* Request NSID */
+	uint8_t	     grease_edns_max_version; /* Currently 0 */
+	uint16_t     grease_edns_known_flags; /* Don't grease these flags */
+	unsigned int grease_rate;	      /* Grease this % of queries */
+	time_t	     grease_until; /* Turn off flags greasing at this time */
+
 	/*
 	 * Configurable data for server use only,
 	 * locked by server configuration lock.
diff --git a/lib/dns/view.c b/lib/dns/view.c
index 963d862723..e6b4a20c8a 100644
--- a/lib/dns/view.c
+++ b/lib/dns/view.c
@@ -120,6 +120,7 @@ dns_view_create(isc_mem_t *mctx, isc_loopmgr_t *loopmgr,
 		.root_key_sentinel = true,
 		.udpsize = DEFAULT_EDNS_BUFSIZE,
 		.max_restarts = DEFAULT_MAX_RESTARTS,
+		.grease_edns_known_flags = DNS_MESSAGEEXTFLAG_KNOWN_FLAGS,
 	};
 
 	isc_refcount_init(&view->references, 1);