First attempt on dynamic reconfiguration. There are still lots of bugs

and problems to solve, but the hardest part works.

TODO

@@ -26,19 +26,21 @@ Core
 - config: executable config files
 - config: when parsing prefix, check zero bits
 - config: reconfiguration
+- config: reconfiguration of filters
 - config: useless rules when protocols disabled
 - config: remove protocol startup priority hacks?
 - config: better datetime format
+- config: treat shutdown as reconfiguration to null config? (what about config of logging etc. ?)
+- config: fix auto_router_id
 
 - krt: rescan interfaces when route addition fails?
 - krt: does PERSIST mode have any sense if kernel syncer is shut down as last?
+- krt: check behaviour wrt. reconfiguration of routing tables
 
 - tagging of external routes?
 
 - io: use poll if available
 
-- port to FreeBSD
-
 Commands
 ~~~~~~~~
 shutdown			# order system shutdown
@@ -50,6 +52,17 @@ show	<name>			# show everything you know about symbol <name>
 	symbols
 (disable|enable|restart) <protocol>	# or ALL?
 - showing of routing table as seen by given protocol
+- showing of deleted routing tables and filters
+
+Roadmap
+~~~~~~~
+- Dynamic reconfiguration
+- Allocators and data structures
+- Client
+- Remaining bits of IPv6 support (radvd)
+- RIPv6
+- BGP?
+- Logging and debugging messages
 
 Client
 ~~~~~~

conf/conf.c

 /*
  *	BIRD Internet Routing Daemon -- Configuration File Handling
  *
- *	(c) 1999 Martin Mares <mj@ucw.cz>
+ *	(c) 1998--2000 Martin Mares <mj@ucw.cz>
  *
  *	Can be freely distributed and used under the terms of the GNU GPL.
  */
@@ -9,18 +9,22 @@
 #include <setjmp.h>
 #include <stdarg.h>
 
+#define LOCAL_DEBUG
+
 #include "nest/bird.h"
 #include "nest/route.h"
 #include "nest/protocol.h"
 #include "nest/iface.h"
 #include "lib/resource.h"
 #include "lib/string.h"
+#include "lib/event.h"
 #include "conf/conf.h"
 #include "filter/filter.h"
 
 static jmp_buf conf_jmpbuf;
 
-struct config *config, *new_config;
+struct config *config, *new_config, *old_config, *future_config;
+static event *config_event;
 
 struct config *
 config_alloc(byte *name)
@@ -77,12 +81,117 @@ config_free(struct config *c)
 }
 
 void
-config_commit(struct config *c)
+config_add_obstacle(struct config *c)
+{
+  DBG("+++ adding obstacle %d\n", c->obstacle_count);
+  c->obstacle_count++;
+}
+
+void
+config_del_obstacle(struct config *c)
 {
+  DBG("+++ deleting obstacle %d\n", c->obstacle_count);
+  c->obstacle_count--;
+  if (!c->obstacle_count)
+    {
+      ASSERT(config_event);
+      ev_schedule(config_event);
+    }
+}
+
+static int
+global_commit(struct config *c, struct config *old)
+{
+  if (!old)
+    return 0;
+  if (c->router_id != old->router_id)
+    return 1;
+  return 0;
+}
+
+static int
+config_do_commit(struct config *c)
+{
+  int force_restart, nobs;
+
+  DBG("do_commit\n");
+  old_config = config;
   config = c;
-  sysdep_commit(c);
-  rt_commit(c);
-  protos_commit(c);
+  if (old_config)
+    old_config->obstacle_count++;
+  DBG("sysdep_commit\n");
+  force_restart = sysdep_commit(c, old_config);
+  DBG("global_commit\n");
+  force_restart |= global_commit(c, old_config);
+  DBG("rt_commit\n");
+  rt_commit(c, old_config);
+  DBG("protos_commit\n");
+  protos_commit(c, old_config, force_restart);
+  new_config = NULL;			/* Just to be sure nobody uses that now */
+  if (old_config)
+    nobs = --old_config->obstacle_count;
+  else
+    nobs = 0;
+  DBG("do_commit finished with %d obstacles remaining\n", nobs);
+  return !nobs;
+}
+
+static int
+config_done(void *unused)
+{
+  struct config *c;
+
+  DBG("config_done\n");
+  for(;;)
+    {
+      log(L_INFO "Reconfigured");
+      if (old_config)
+	{
+	  config_free(old_config);
+	  old_config = NULL;
+	}
+      if (!future_config)
+	break;
+      c = future_config;
+      future_config = NULL;
+      log(L_INFO "Switching to queued configuration...");
+      if (!config_do_commit(c))
+	break;
+    }
+  return 0;
+}
+
+int
+config_commit(struct config *c)
+{
+  if (!config)				/* First-time configuration */
+    {
+      config_do_commit(c);
+      return CONF_DONE;
+    }
+  if (old_config)			/* Reconfiguration already in progress */
+    {
+      if (future_config)
+	{
+	  log(L_INFO "Queueing new configuration, ignoring the one already queued");
+	  config_free(future_config);
+	}
+      else
+	log(L_INFO "Queued new configuration");
+      future_config = c;
+      return CONF_QUEUED;
+    }
+  if (config_do_commit(c))
+    {
+      config_done(NULL);
+      return CONF_DONE;
+    }
+  if (!config_event)
+    {
+      config_event = ev_new(&root_pool);
+      config_event->hook = config_done;
+    }
+  return CONF_PROGRESS;
 }
 
 void

conf/conf.h

 /*
  *	BIRD Internet Routing Daemon -- Configuration File Handling
  *
- *	(c) 1998--1999 Martin Mares <mj@ucw.cz>
+ *	(c) 1998--2000 Martin Mares <mj@ucw.cz>
  *
  *	Can be freely distributed and used under the terms of the GNU GPL.
  */
@@ -26,17 +26,27 @@ struct config {
   char *file_name;			/* Name of configuration file */
   struct symbol **sym_hash;		/* Lexer: symbol hash table */
   struct symbol **sym_fallback;		/* Lexer: fallback symbol hash table */
+  int obstacle_count;			/* Number of items blocking freeing of this config */
 };
 
-extern struct config *config, *new_config;
 /* Please don't use these variables in protocols. Use proto_config->global instead. */
+extern struct config *config;		/* Currently active configuration */
+extern struct config *new_config;	/* Configuration being parsed */
+extern struct config *old_config;	/* Old configuration when reconfiguration is in progress */
+extern struct config *future_config;	/* New config held here if recon requested during recon */
 
 struct config *config_alloc(byte *name);
 int config_parse(struct config *);
 int cli_parse(struct config *);
 void config_free(struct config *);
-void config_commit(struct config *);
+int config_commit(struct config *);
 void cf_error(char *msg, ...) NORET;
+void config_add_obstacle(struct config *);
+void config_del_obstacle(struct config *);
+
+#define CONF_DONE 0
+#define CONF_PROGRESS 1
+#define CONF_QUEUED 2
 
 /* Pools */
 
@@ -87,6 +97,6 @@ int cf_parse(void);
 /* Sysdep hooks */
 
 void sysdep_preconfig(struct config *);
-void sysdep_commit(struct config *);
+int sysdep_commit(struct config *, struct config *);
 
 #endif

doc/reply_codes

@@ -10,6 +10,7 @@ Reply codes of BIRD command-line interface
 
 0000	OK
 0001	Welcome
+0002	Reading configuration
 
 1000	BIRD version
 1001	Interface list
@@ -24,6 +25,7 @@ Reply codes of BIRD command-line interface
 
 8000	Reply too long
 8001	Route not found
+8002	Configuration file error
 
 9000	Command too long
 9001	Parse error

nest/proto.c

 /*
  *	BIRD -- Protocols
  *
- *	(c) 1998--1999 Martin Mares <mj@ucw.cz>
+ *	(c) 1998--2000 Martin Mares <mj@ucw.cz>
  *
  *	Can be freely distributed and used under the terms of the GNU GPL.
  */
@@ -38,6 +38,7 @@ static char *p_states[] = { "DOWN", "START", "UP", "STOP" };
 static char *c_states[] = { "HUNGRY", "FEEDING", "HAPPY", "FLUSHING" };
 
 static int proto_flush_all(void *);
+static void proto_rethink_goal(struct proto *p);
 
 static void
 proto_enqueue(list *l, struct proto *p)
@@ -103,6 +104,7 @@ proto_init_instance(struct proto *p)
   p->pool = rp_new(proto_pool, p->proto->name);
   p->attn = ev_new(p->pool);
   p->attn->data = p;
+  rt_lock_table(p->table);
 }
 
 struct announce_hook *
@@ -185,42 +187,118 @@ protos_postconfig(struct config *c)
   debug("\n");
 }
 
+static struct proto *
+proto_init(struct proto_config *c)
+{
+  struct protocol *p = c->protocol;
+  struct proto *q = p->init(c);
+
+  q->proto_state = PS_DOWN;
+  q->core_state = FS_HUNGRY;
+  proto_enqueue(&initial_proto_list, q);
+  /*
+   *  HACK ALERT!  In case of multiple kernel routing tables,
+   *  the kernel syncer acts as multiple protocols which cooperate
+   *  with each other.  In order to speed up their initialization,
+   *  we need to know when we're initializing the last one, hence
+   *  the startup counter.
+   */
+  if (!q->disabled)
+    p->startup_counter++;
+  return q;
+}
+
 void
-protos_commit(struct config *c)
+protos_commit(struct config *new, struct config *old, int force_reconfig)
 {
-  struct proto_config *x;
-  struct protocol *p;
-  struct proto *q;
+  struct proto_config *oc, *nc;
+  struct proto *p, *n;
 
-  debug("Protocol commit:");
-  WALK_LIST(x, c->protos)
+  DBG("protos_commit:\n");
+  if (old)
     {
-      debug(" %s", x->name);
-      p = x->protocol;
-      q = p->init(x);
-      q->proto_state = PS_DOWN;
-      q->core_state = FS_HUNGRY;
-      proto_enqueue(&initial_proto_list, q);
-      /*
-       *  HACK ALERT!  In case of multiple kernel routing tables,
-       *  the kernel syncer acts as multiple protocols which cooperate
-       *  with each other.  In order to speed up their initialization,
-       *  we need to know when we're initializing the last one, hence
-       *  the startup counter.
-       */
-      if (!q->disabled)
-	p->startup_counter++;
+      WALK_LIST(oc, old->protos)
+	{
+	  struct proto *p = oc->proto;
+	  struct symbol *sym = cf_find_symbol(oc->name);
+	  if (sym && sym->class == SYM_PROTO)
+	    {
+	      /* Found match, let's check if we can smoothly switch to new configuration */
+	      nc = sym->def;
+	      if (!force_reconfig
+		  && nc->protocol == oc->protocol
+		  && nc->preference == oc->preference
+		  && nc->disabled == oc->disabled
+		  && nc->table->table == oc->table->table
+		  && nc->in_filter == oc->in_filter
+		  && nc->out_filter == oc->out_filter
+		  && p->proto_state != PS_DOWN)
+		{
+		  /* Generic attributes match, try converting them and then ask the protocol */
+		  p->debug = nc->debug;
+		  if (p->proto->reconfigure(p, nc))
+		    {
+		      DBG("\t%s: same\n", oc->name);
+		      p->cf = nc;
+		      nc->proto = p;
+		      continue;
+		    }
+		}
+	      /* Unsuccessful, force reconfig */
+	      DBG("\t%s: power cycling\n", oc->name);
+	      p->cf_new = nc;
+	    }
+	  else
+	    {
+	      DBG("\t%s: deleting\n", oc->name);
+	      p->cf_new = NULL;
+	    }
+	  p->reconfiguring = 1;
+	  config_add_obstacle(old);
+	  proto_rethink_goal(p);
+	}
     }
-  debug("\n");
+
+  WALK_LIST(nc, new->protos)
+    if (!nc->proto)
+      {
+	DBG("\t%s: adding\n", nc->name);
+	proto_init(nc);
+      }
+  DBG("\tdone\n");
+
+  DBG("Protocol start\n");
+  WALK_LIST_DELSAFE(p, n, initial_proto_list)
+    proto_rethink_goal(p);
 }
 
 static void
 proto_rethink_goal(struct proto *p)
 {
-  struct protocol *q = p->proto;
+  struct protocol *q;
+
+  if (p->reconfiguring && p->core_state == FS_HUNGRY && p->proto_state == PS_DOWN)
+    {
+      struct proto_config *nc = p->cf_new;
+      DBG("%s has shut down for reconfiguration\n", p->name);
+      config_del_obstacle(p->cf->global);
+      rem_node(&p->n);
+      mb_free(p);
+      if (!nc)
+	return;
+      p = proto_init(nc);		/* FIXME: What about protocol priorities??? */
+    }
+
+  /* Determine what state we want to reach */
+  if (p->disabled || shutting_down || p->reconfiguring)
+    p->core_goal = FS_HUNGRY;
+  else
+    p->core_goal = FS_HAPPY;
 
   if (p->core_state == p->core_goal)
     return;
+
+  q = p->proto;
   if (p->core_goal == FS_HAPPY)		/* Going up */
     {
       if (p->core_state == FS_HUNGRY && p->proto_state == PS_DOWN)
@@ -242,25 +320,6 @@ proto_rethink_goal(struct proto *p)
     }
 }
 
-static void
-proto_set_goal(struct proto *p, unsigned goal)
-{
-  if (p->disabled || shutting_down)
-    goal = FS_HUNGRY;
-  p->core_goal = goal;
-  proto_rethink_goal(p);
-}
-
-void
-protos_start(void)
-{
-  struct proto *p, *n;
-
-  debug("Protocol start\n");
-  WALK_LIST_DELSAFE(p, n, initial_proto_list)
-    proto_set_goal(p, FS_HAPPY);
-}
-
 void
 protos_shutdown(void)
 {
@@ -271,12 +330,12 @@ protos_shutdown(void)
     if (p->core_state != FS_HUNGRY || p->proto_state != PS_DOWN)
     {
       proto_shutdown_counter++;
-      proto_set_goal(p, FS_HUNGRY);
+      proto_rethink_goal(p);
     }
   WALK_LIST_BACKWARDS_DELSAFE(p, n, proto_list)
     {
       proto_shutdown_counter++;
-      proto_set_goal(p, FS_HUNGRY);
+      proto_rethink_goal(p);
     }
 }
 
@@ -329,6 +388,7 @@ static void
 proto_fell_down(struct proto *p)
 {
   DBG("Protocol %s down\n", p->name);
+  rt_unlock_table(p->table);
   if (!--proto_shutdown_counter)
     protos_shutdown_notify();
   proto_rethink_goal(p);
@@ -363,7 +423,10 @@ proto_notify_state(struct proto *p, unsigned ps)
     {
     case PS_DOWN:
       if (cs == FS_HUNGRY)		/* Shutdown finished */
-	proto_fell_down(p);
+	{
+	  proto_fell_down(p);
+	  return;			/* The protocol might have ceased to exist */
+	}
       else if (cs == FS_FLUSHING)	/* Still flushing... */
 	;
       else				/* Need to start flushing */

nest/protocol.h

@@ -41,7 +41,7 @@ struct protocol {
   void (*preconfig)(struct protocol *, struct config *);	/* Just before configuring */
   void (*postconfig)(struct proto_config *);			/* After configuring each instance */
   struct proto * (*init)(struct proto_config *);		/* Create new instance */
-  int (*reconfigure)(struct proto *, struct proto_config *);	/* Try to reconfigure instance */
+  int (*reconfigure)(struct proto *, struct proto_config *);	/* Try to reconfigure instance, returns success */
   void (*dump)(struct proto *);			/* Debugging dump */
   void (*dump_attrs)(struct rte *);		/* Dump protocol-dependent attributes */
   int (*start)(struct proto *);			/* Start the instance */
@@ -54,8 +54,7 @@ struct protocol {
 void protos_build(void);
 void protos_preconfig(struct config *);
 void protos_postconfig(struct config *);
-void protos_commit(struct config *);
-void protos_start(void);
+void protos_commit(struct config *new, struct config *old, int force_restart);
 void protos_dump_all(void);
 void protos_shutdown(void);
 
@@ -92,6 +91,7 @@ struct proto {
   node n;
   struct protocol *proto;		/* Protocol */
   struct proto_config *cf;		/* Configuration data */
+  struct proto_config *cf_new;		/* Configuration we want to switch to after shutdown (NULL=delete) */
   pool *pool;				/* Pool containing local objects */
   struct event *attn;			/* "Pay attention" event */
 
@@ -103,6 +103,7 @@ struct proto {
   unsigned proto_state;			/* Protocol state machine (see below) */
   unsigned core_state;			/* Core state machine (see below) */
   unsigned core_goal;			/* State we want to reach (see below) */
+  unsigned reconfiguring;		/* We're shutting down due to reconfiguration */
   bird_clock_t last_state_change;	/* Time of last state transition */
 
   /*

nest/route.h

 /*
  *	BIRD Internet Routing Daemon -- Routing Table
  *
- *	(c) 1998--1999 Martin Mares <mj@ucw.cz>
+ *	(c) 1998--2000 Martin Mares <mj@ucw.cz>
  *
  *	Can be freely distributed and used under the terms of the GNU GPL.
  */
@@ -121,6 +121,11 @@ typedef struct rtable {
   char *name;				/* Name of this table */
   list hooks;				/* List of announcement hooks */
   int pipe_busy;			/* Pipe loop detection */
+  int use_count;			/* Number of protocols using this table */
+  struct config *deleted;		/* Table doesn't exist in current configuration,
+					 * delete as soon as use_count becomes 0 and remove
+					 * obstacle from this routing table.
+					 */
 } rtable;
 
 typedef struct network {
@@ -171,7 +176,9 @@ struct config;
 
 void rt_init(void);
 void rt_preconfig(struct config *);
-void rt_commit(struct config *);
+void rt_commit(struct config *new, struct config *old);
+void rt_lock_table(rtable *);
+void rt_unlock_table(rtable *);
 void rt_setup(pool *, rtable *, char *);
 static inline net *net_find(rtable *tab, ip_addr addr, unsigned len) { return (net *) fib_find(&tab->fib, &addr, len); }
 static inline net *net_get(rtable *tab, ip_addr addr, unsigned len) { return (net *) fib_get(&tab->fib, &addr, len); }

nest/rt-table.c

 /*
  *	BIRD -- Routing Table
  *
- *	(c) 1998--1999 Martin Mares <mj@ucw.cz>
+ *	(c) 1998--2000 Martin Mares <mj@ucw.cz>
  *
  *	Can be freely distributed and used under the terms of the GNU GPL.
  */
@@ -480,17 +480,68 @@ rt_preconfig(struct config *c)
 }
 
 void
-rt_commit(struct config *c)
+rt_lock_table(rtable *r)
 {
-  struct rtable_config *r;
+  r->use_count++;
+}
+
+void
+rt_unlock_table(rtable *r)
+{
+  if (!--r->use_count && r->deleted)
+    {
+      struct config *conf = r->deleted;
+      DBG("Deleting routing table %s\n", r->name);
+      rem_node(&r->n);
+      fib_free(&r->fib);
+      mb_free(r);
+      config_del_obstacle(conf);
+    }
+}
+
+void
+rt_commit(struct config *new, struct config *old)
+{
+  struct rtable_config *o, *r;
 
-  WALK_LIST(r, c->tables)
+  DBG("rt_commit:\n");
+  if (old)
     {
-      rtable *t = mb_alloc(rt_table_pool, sizeof(struct rtable));
-      rt_setup(rt_table_pool, t, r->name);
-      add_tail(&routing_tables, &t->n);
-      r->table = t;
+      WALK_LIST(o, old->tables)
+	{
+	  rtable *ot = o->table;
+	  if (!ot->deleted)
+	    {
+	      struct symbol *sym = cf_find_symbol(o->name);
+	      if (sym && sym->class == SYM_TABLE)
+		{
+		  DBG("\t%s: same\n", o->name);
+		  r = sym->def;
+		  r->table = ot;
+		  ot->name = r->name;
+		}
+	      else
+		{
+		  DBG("\t%s: deleted", o->name);
+		  ot->deleted = old;
+		  config_add_obstacle(old);
+		  rt_lock_table(ot);
+		  rt_unlock_table(ot);
+		}
+	    }
+	}
     }
+
+  WALK_LIST(r, new->tables)
+    if (!r->table)
+      {
+	rtable *t = mb_alloc(rt_table_pool, sizeof(struct rtable));
+	DBG("\t%s: created\n", r->name);
+	rt_setup(rt_table_pool, t, r->name);
+	add_tail(&routing_tables, &t->n);
+	r->table = t;
+      }
+  DBG("\tdone\n");
 }
 
 /*

proto/pipe/pipe.c

 /*
  *	BIRD -- Table-to-Table Routing Protocol a.k.a Pipe
  *
- *	(c) 1999 Martin Mares <mj@ucw.cz>
+ *	(c) 1999--2000 Martin Mares <mj@ucw.cz>
  *
  *	Can be freely distributed and used under the terms of the GNU GPL.
  */
@@ -106,10 +106,20 @@ pipe_start(struct proto *P)
    */
   a = proto_add_announce_hook(P, p->peer);
   a->proto = &ph->p;
+  rt_lock_table(p->peer);
 
   return PS_UP;
 }
 
+static int
+pipe_shutdown(struct proto *P)
+{
+  struct pipe_proto *p = (struct pipe_proto *) P;
+
+  rt_unlock_table(p->peer);
+  return PS_DOWN;
+}
+
 static struct proto *
 pipe_init(struct proto_config *C)