From 63472779ad4ecdecbcfedf2d2bb40abc2f8c84b0 Mon Sep 17 00:00:00 2001
From: "Ondrej Zajicek (work)" <santiago@crfreenet.org>
Date: Tue, 16 Jan 2018 19:17:04 +0100
Subject: [PATCH] BGP: Implement 'disable after cease' option

The option allows to specify that some cease subcodes should
disable the protocol when received.
---
 proto/bgp/bgp.h     |  1 +
 proto/bgp/config.Y  | 30 ++++++++++++++++++++++++++++++
 proto/bgp/packets.c | 10 ++++++++++
 3 files changed, 41 insertions(+)

diff --git a/proto/bgp/bgp.h b/proto/bgp/bgp.h
index 22a150ab..b3db8b7e 100644
--- a/proto/bgp/bgp.h
+++ b/proto/bgp/bgp.h
@@ -62,6 +62,7 @@ struct bgp_config {
   unsigned error_delay_time_min;	/* Time to wait after an error is detected */
   unsigned error_delay_time_max;
   unsigned disable_after_error;		/* Disable the protocol when error is detected */
+  u32 disable_after_cease;		/* Disable it when cease is received, bitfield */
 
   char *password;			/* Password used for MD5 authentication */
   struct rtable_config *igp_table;	/* Table used for recursive next hop lookups */
diff --git a/proto/bgp/config.Y b/proto/bgp/config.Y
index 55c602f1..075403a3 100644
--- a/proto/bgp/config.Y
+++ b/proto/bgp/config.Y
@@ -29,6 +29,12 @@ CF_KEYWORDS(BGP, LOCAL, NEIGHBOR, AS, HOLD, TIME, CONNECT, RETRY,
 	SECONDARY, ALLOW, BFD, ADD, PATHS, RX, TX, GRACEFUL, RESTART, AWARE,
 	CHECK, LINK, PORT, EXTENDED, MESSAGES, SETKEY, BGP_LARGE_COMMUNITY)
 
+CF_KEYWORDS(CEASE, PREFIX, LIMIT, HIT, ADMINISTRATIVE, SHUTDOWN, RESET, PEER,
+	CONFIGURATION, CHANGE, DECONFIGURED, CONNECTION, REJECTED, COLLISION,
+	OUT, OF, RESOURCES)
+
+%type<i> bgp_cease_mask bgp_cease_list bgp_cease_flag
+
 CF_GRAMMAR
 
 CF_ADDTO(proto, bgp_proto '}' { bgp_check_config(BGP_CFG); } )
@@ -64,6 +70,29 @@ bgp_nbr_opts:
  | bgp_nbr_opts AS expr { BGP_CFG->remote_as = $3; }
  ;
 
+bgp_cease_mask:
+   /* true -> all except connection collision */
+   bool { $$ = $1 ? ~(1 << 7) : 0; }
+ | '{' bgp_cease_list '}' { $$ = $2; }
+ ;
+
+bgp_cease_list:
+   bgp_cease_flag
+ | bgp_cease_list ',' bgp_cease_flag { $$ = $1 | $3; }
+ ;
+
+bgp_cease_flag:
+   CEASE			{ $$ = 1 << 0; }
+ | PREFIX LIMIT HIT		{ $$ = 1 << 1; }
+ | ADMINISTRATIVE SHUTDOWN	{ $$ = 1 << 2; }
+ | PEER DECONFIGURED		{ $$ = 1 << 3; }
+ | ADMINISTRATIVE RESET		{ $$ = 1 << 4; }
+ | CONNECTION REJECTED		{ $$ = 1 << 5; }
+ | CONFIGURATION CHANGE		{ $$ = 1 << 6; }
+ | CONNECTION COLLISION		{ $$ = 1 << 7; }
+ | OUT OF RESOURCES		{ $$ = 1 << 8; }
+ ;
+
 bgp_proto:
    bgp_proto_start proto_name '{'
  | bgp_proto proto_item ';'
@@ -107,6 +136,7 @@ bgp_proto:
  | bgp_proto ERROR FORGET TIME expr ';' { BGP_CFG->error_amnesia_time = $5; }
  | bgp_proto ERROR WAIT TIME expr ',' expr ';' { BGP_CFG->error_delay_time_min = $5; BGP_CFG->error_delay_time_max = $7; }
  | 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 AS4 bool ';' { BGP_CFG->enable_as4 = $4; }
  | bgp_proto ENABLE EXTENDED MESSAGES bool ';' { BGP_CFG->enable_extended_messages = $5; }
diff --git a/proto/bgp/packets.c b/proto/bgp/packets.c
index af3b15b5..f0049d3a 100644
--- a/proto/bgp/packets.c
+++ b/proto/bgp/packets.c
@@ -1607,6 +1607,16 @@ bgp_rx_notification(struct bgp_conn *conn, byte *pkt, uint len)
       bgp_update_startup_delay(p);
       bgp_stop(p, 0, NULL, 0);
     }
+  else
+    {
+      uint subcode_bit = 1 << ((subcode <= 8) ? subcode : 0);
+      if (p->cf->disable_after_cease & subcode_bit)
+      {
+	log(L_INFO "%s: Disabled after Cease notification", p->p.name);
+	p->startup_delay = 0;
+	p->p.disabled = 1;
+      }
+    }
 }
 
 static void