Nest: Add command to request graceful restart

When 'graceful down' command is entered, protocols are shut down
with regard to graceful restart. Namely Kernel protocol does
not remove routes and BGP protocol does not send notification,
just closes the connection.

conf/conf.c

@@ -474,19 +474,24 @@ config_init(void)
  * for switching to an empty configuration.
  */
 void
-order_shutdown(void)
+order_shutdown(int gr)
 {
   struct config *c;
 
   if (shutting_down)
     return;
 
+  if (!gr)
     log(L_INFO "Shutting down");
+  else
+    log(L_INFO "Shutting down for graceful restart");
+
   c = lp_alloc(config->mem, sizeof(struct config));
   memcpy(c, config, sizeof(struct config));
   init_list(&c->protos);
   init_list(&c->tables);
   c->shutdown = 1;
+  c->gr_down = gr;
 
   config_commit(c, RECONFIG_HARD, 0);
   shutting_down = 1;

conf/conf.h

@@ -56,6 +56,7 @@ struct config {
   struct config *fallback;		/* Link to regular config for CLI parsing */
   int obstacle_count;			/* Number of items blocking freeing of this config */
   int shutdown;				/* This is a pseudo-config for daemon shutdown */
+  int gr_down;				/* This is a pseudo-config for graceful restart */
   btime load_time;			/* When we've got this configuration */
 };
 
@@ -74,7 +75,7 @@ void config_init(void);
 void cf_error(const char *msg, ...) NORET;
 void config_add_obstacle(struct config *);
 void config_del_obstacle(struct config *);
-void order_shutdown(void);
+void order_shutdown(int gr);
 
 #define RECONFIG_NONE	0
 #define RECONFIG_HARD	1

doc/reply_codes

@@ -33,6 +33,7 @@ Reply codes of BIRD command-line interface
 0022	Undo scheduled
 0023	Evaluation of expression
 0024	Graceful restart status report
+0025	Graceful restart ordered
 
 1000	BIRD version
 1001	Interface list

nest/proto.c

@@ -993,6 +993,11 @@ protos_commit(struct config *new, struct config *old, int force_reconfig, int ty
 	p->down_code = PDC_CF_REMOVE;
 	p->cf_new = NULL;
       }
+      else if (new->gr_down)
+      {
+	p->down_code = PDC_CMD_GR_DOWN;
+	p->cf_new = NULL;
+      }
       else /* global shutdown */
       {
 	p->down_code = PDC_CMD_SHUTDOWN;

nest/protocol.h

@@ -234,6 +234,7 @@ struct proto_spec {
 #define PDC_CMD_DISABLE		0x11	/* Result of disable command */
 #define PDC_CMD_RESTART		0x12	/* Result of restart command */
 #define PDC_CMD_SHUTDOWN	0x13	/* Result of global shutdown */
+#define PDC_CMD_GR_DOWN		0x14	/* Result of global graceful restart */
 #define PDC_RX_LIMIT_HIT	0x21	/* Route receive limit reached */
 #define PDC_IN_LIMIT_HIT	0x22	/* Route import limit reached */
 #define PDC_OUT_LIMIT_HIT	0x23	/* Route export limit reached */

proto/bgp/bgp.c

@@ -406,7 +406,7 @@ bgp_update_startup_delay(struct bgp_proto *p)
 }
 
 static void
-bgp_graceful_close_conn(struct bgp_conn *conn, uint subcode, byte *data, uint len)
+bgp_graceful_close_conn(struct bgp_conn *conn, int subcode, byte *data, uint len)
 {
   switch (conn->state)
   {
@@ -422,6 +422,12 @@ bgp_graceful_close_conn(struct bgp_conn *conn, uint subcode, byte *data, uint le
   case BS_OPENSENT:
   case BS_OPENCONFIRM:
   case BS_ESTABLISHED:
+    if (subcode < 0)
+    {
+      bgp_conn_enter_close_state(conn);
+      bgp_schedule_packet(conn, NULL, PKT_SCHEDULE_CLOSE);
+    }
+    else
       bgp_error(conn, 6, subcode, data, len);
     return;
 
@@ -462,7 +468,7 @@ bgp_decision(void *vp)
 }
 
 void
-bgp_stop(struct bgp_proto *p, uint subcode, byte *data, uint len)
+bgp_stop(struct bgp_proto *p, int subcode, byte *data, uint len)
 {
   proto_notify_state(&p->p, PS_STOP);
   bgp_graceful_close_conn(&p->outgoing_conn, subcode, data, len);
@@ -1379,7 +1385,7 @@ static int
 bgp_shutdown(struct proto *P)
 {
   struct bgp_proto *p = (struct bgp_proto *) P;
-  uint subcode = 0;
+  int subcode = 0;
 
   char *message = NULL;
   byte *data = NULL;
@@ -1400,6 +1406,7 @@ bgp_shutdown(struct proto *P)
 
   case PDC_CMD_DISABLE:
   case PDC_CMD_SHUTDOWN:
+  shutdown:
     subcode = 2; // Errcode 6, 2 - administrative shutdown
     message = P->message;
     break;
@@ -1409,6 +1416,13 @@ bgp_shutdown(struct proto *P)
     message = P->message;
     break;
 
+  case PDC_CMD_GR_DOWN:
+    if (p->cf->gr_mode != BGP_GR_ABLE)
+      goto shutdown;
+
+    subcode = -1; // Do not send NOTIFICATION, just close the connection
+    break;
+
   case PDC_RX_LIMIT_HIT:
   case PDC_IN_LIMIT_HIT:
     subcode = 1; // Errcode 6, 1 - max number of prefixes reached

proto/bgp/bgp.h

@@ -453,7 +453,7 @@ void bgp_graceful_restart_done(struct bgp_channel *c);
 void bgp_refresh_begin(struct bgp_channel *c);
 void bgp_refresh_end(struct bgp_channel *c);
 void bgp_store_error(struct bgp_proto *p, struct bgp_conn *c, u8 class, u32 code);
-void bgp_stop(struct bgp_proto *p, uint subcode, byte *data, uint len);
+void bgp_stop(struct bgp_proto *p, int subcode, byte *data, uint len);
 
 struct rte_source *bgp_find_source(struct bgp_proto *p, u32 path_id);
 struct rte_source *bgp_get_source(struct bgp_proto *p, u32 path_id);

sysdep/unix/config.Y

@@ -130,6 +130,10 @@ CF_CLI(CONFIGURE CHECK, cfg_name, [\"<file>\"], [[Parse configuration and check
 CF_CLI(DOWN,,, [[Shut the daemon down]])
 { cmd_shutdown(); } ;
 
+CF_CLI(GRACEFUL DOWN,,, [[Shut the daemon down for graceful restart]])
+{ cmd_graceful_restart(); } ;
+
+
 cfg_name:
    /* empty */ { $$ = NULL; }
  | TEXT

sysdep/unix/krt.c

@@ -1146,7 +1146,7 @@ krt_shutdown(struct proto *P)
   krt_scan_timer_stop(p);
 
   /* FIXME we should flush routes even when persist during reconfiguration */
-  if (p->initialized && !KRT_CF->persist)
+  if (p->initialized && !KRT_CF->persist && (P->down_code != PDC_CMD_GR_DOWN))
     krt_flush_routes(p);
 
   p->ready = 0;

sysdep/unix/main.c

@@ -549,14 +549,14 @@ cmd_shutdown(void)
     return;
 
   cli_msg(7, "Shutdown requested");
-  order_shutdown();
+  order_shutdown(0);
 }
 
 void
 async_shutdown(void)
 {
   DBG("Shutting down...\n");
-  order_shutdown();
+  order_shutdown(0);
 }
 
 void
@@ -568,6 +568,17 @@ sysdep_shutdown_done(void)
   exit(0);
 }
 
+void
+cmd_graceful_restart(void)
+{
+  if (cli_access_restricted())
+    return;
+
+  cli_msg(25, "Graceful restart requested");
+  order_shutdown(1);
+}
+
+
 /*
  *	Signals
  */

sysdep/unix/unix.h

@@ -27,6 +27,7 @@ void cmd_reconfig(char *name, int type, uint timeout);
 void cmd_reconfig_confirm(void);
 void cmd_reconfig_undo(void);
 void cmd_shutdown(void);
+void cmd_graceful_restart(void);
 
 #define UNIX_DEFAULT_CONFIGURE_TIMEOUT	300