From 8ad9c4bb339172d445d1346876b2c9f3c27199c1 Mon Sep 17 00:00:00 2001
From: Maria Matejka <mq@ucw.cz>
Date: Wed, 27 Sep 2023 12:51:55 +0200
Subject: BGP config: Splitting Route Refresh and Enhanced Route Refresh

Both toggles are on by default but if some implementation needs one or
another to be switched off separately, then it's possible now.
---
 doc/bird.sgml       | 19 +++++++++++++------
 proto/bgp/bgp.h     |  1 +
 proto/bgp/config.Y  |  4 +++-
 proto/bgp/packets.c |  2 +-
 4 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/doc/bird.sgml b/doc/bird.sgml
index 449a69de..09da89df 100644
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -2799,13 +2799,20 @@ using the following configuration parameters:
 	changes its import filter, or if there is suspicion of inconsistency) it
 	is necessary to do a new complete route exchange. BGP protocol extension
 	Route Refresh (<rfc id="2918">) allows BGP speaker to request
-	re-advertisement of all routes from its neighbor. BGP protocol
-	extension Enhanced Route Refresh (<rfc id="7313">) specifies explicit
-	begin and end for such exchanges, therefore the receiver can remove
-	stale routes that were not advertised during the exchange. This option
-	specifies whether BIRD advertises these capabilities and supports
+	re-advertisement of all routes from its neighbor. This option
+	specifies whether BIRD advertises this capability and supports
 	related procedures. Note that even when disabled, BIRD can send route
-	refresh requests.  Default: on.
+	refresh requests. Disabling Route Refresh also disables Enhanced Route Refresh.
+	Default: on.
+
+	<tag><label id="bgp-enable-enhanced-route-refresh">enable enhanced route refresh <m/switch/</tag>
+	BGP protocol extension Enhanced Route Refresh (<rfc id="7313">) specifies explicit
+	begin and end for Route Refresh (see previous option),
+	therefore the receiver can remove
+	stale routes that were not advertised during the exchange. This option
+	specifies whether BIRD advertises this capability and supports
+	related procedures.
+	Default: on.
 
 	<tag><label id="bgp-graceful-restart">graceful restart <m/switch/|aware</tag>
 	When a BGP speaker restarts or crashes, neighbors will discard all
diff --git a/proto/bgp/bgp.h b/proto/bgp/bgp.h
index c11433ec..1ba3de5e 100644
--- a/proto/bgp/bgp.h
+++ b/proto/bgp/bgp.h
@@ -96,6 +96,7 @@ struct bgp_config {
   u32 default_med;			/* Default value for MULTI_EXIT_DISC attribute */
   int capabilities;			/* Enable capability handshake [RFC 5492] */
   int enable_refresh;			/* Enable local support for route refresh [RFC 2918] */
+  int enable_enhanced_refresh;		/* Enable local support for enhanced route refresh [RFC 7313] */
   int enable_as4;			/* Enable local support for 4B AS numbers [RFC 6793] */
   int enable_extended_messages;		/* Enable local support for extended messages [RFC 8654] */
   int enable_hostname;			/* Enable local support for hostname [draft] */
diff --git a/proto/bgp/config.Y b/proto/bgp/config.Y
index d9ff24d8..f589fd84 100644
--- a/proto/bgp/config.Y
+++ b/proto/bgp/config.Y
@@ -24,7 +24,7 @@ CF_KEYWORDS(BGP, LOCAL, NEIGHBOR, AS, HOLD, TIME, CONNECT, RETRY, KEEPALIVE,
 	BGP_AGGREGATOR, BGP_COMMUNITY, BGP_EXT_COMMUNITY, BGP_LARGE_COMMUNITY,
 	SOURCE, ADDRESS, PASSWORD, RR, RS, CLIENT, CLUSTER, ID, AS4, ADVERTISE,
 	IPV4, CAPABILITIES, LIMIT, PASSIVE, PREFER, OLDER, MISSING, LLADDR,
-	DROP, IGNORE, ROUTE, REFRESH, INTERPRET, COMMUNITIES, BGP_ORIGINATOR_ID,
+	DROP, IGNORE, ENHANCED, ROUTE, REFRESH, INTERPRET, COMMUNITIES, BGP_ORIGINATOR_ID,
 	BGP_CLUSTER_LIST, IGP, TABLE, GATEWAY, DIRECT, RECURSIVE, MED, TTL,
 	SECURITY, DETERMINISTIC, SECONDARY, ALLOW, BFD, ADD, PATHS, RX, TX,
 	GRACEFUL, RESTART, AWARE, CHECK, LINK, PORT, EXTENDED, MESSAGES, SETKEY,
@@ -62,6 +62,7 @@ bgp_proto_start: proto_start BGP {
      BGP_CFG->error_delay_time_min = 60;
      BGP_CFG->error_delay_time_max = 300;
      BGP_CFG->enable_refresh = 1;
+     BGP_CFG->enable_enhanced_refresh = 1;
      BGP_CFG->enable_as4 = 1;
      BGP_CFG->enable_hostname = 0;
      BGP_CFG->capabilities = 2;
@@ -185,6 +186,7 @@ bgp_proto:
  | bgp_proto DISABLE AFTER ERROR bool ';' { BGP_CFG->disable_after_error = $5; }
  | bgp_proto DISABLE AFTER CEASE bgp_cease_mask ';' { BGP_CFG->disable_after_cease = $5; }
  | bgp_proto ENABLE ROUTE REFRESH bool ';' { BGP_CFG->enable_refresh = $5; }
+ | bgp_proto ENABLE ENHANCED ROUTE REFRESH bool ';' { BGP_CFG->enable_enhanced_refresh = $6; }
  | bgp_proto ENABLE AS4 bool ';' { BGP_CFG->enable_as4 = $4; }
  | bgp_proto ENABLE EXTENDED MESSAGES bool ';' { BGP_CFG->enable_extended_messages = $5; }
  | bgp_proto ADVERTISE HOSTNAME bool ';' { BGP_CFG->enable_hostname = $4; }
diff --git a/proto/bgp/packets.c b/proto/bgp/packets.c
index dc52e805..fd7828f0 100644
--- a/proto/bgp/packets.c
+++ b/proto/bgp/packets.c
@@ -245,7 +245,7 @@ bgp_prepare_capabilities(struct bgp_conn *conn)
   caps->as4_support = p->cf->enable_as4;
   caps->ext_messages = p->cf->enable_extended_messages;
   caps->route_refresh = p->cf->enable_refresh;
-  caps->enhanced_refresh = p->cf->enable_refresh;
+  caps->enhanced_refresh = p->cf->enable_refresh && p->cf->enable_enhanced_refresh;
   caps->role = p->cf->local_role;
 
   if (caps->as4_support)
-- 
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