Implements interface masks for choosing router id.

Router ID could be automatically determined based of subset of
ifaces/addresses specified by 'router id from' option. The patch also
does some minor changes related to router ID reconfiguration.

Thanks to Alexander V. Chernikov for most of the work.

conf/conf.c

@@ -200,9 +200,19 @@ global_commit(struct config *new, struct config *old)
     log(L_WARN "Reconfiguration of BGP listening socket not implemented, please restart BIRD.");
 
   if (!new->router_id)
-    new->router_id = old->router_id;
-  if (new->router_id != old->router_id)
-    return 1;
+    {
+      new->router_id = old->router_id;
+
+      if (new->router_id_from)
+	{
+	  u32 id = if_choose_router_id(new->router_id_from, old->router_id);
+	  if (!id)
+	    log(L_WARN "Cannot determine router ID, using old one");
+	  else
+	    new->router_id = id;
+	}
+    }
+
   return 0;
 }
 

conf/conf.h

@@ -26,6 +26,7 @@ struct config {
   int mrtdump_file;			/* Configured MRTDump file (sysdep, fd in unix) */
   char *syslog_name;			/* Name used for syslog (NULL -> no syslog) */
   struct rtable_config *master_rtc;	/* Configuration of master routing table */
+  struct iface_patt *router_id_from;	/* Configured list of router ID iface patterns */
 
   u32 router_id;			/* Our Router ID */
   ip_addr listen_bgp_addr;		/* Listening BGP socket should use this address */

doc/bird.sgml

@@ -337,7 +337,18 @@ protocol rip {
 	Besides, there are some predefined numeric constants based on /etc/iproute2/rt_* files.
 	A list of defined constants can be seen (together with other symbols) using 'show symbols' command.
 
-	<tag>router id <m/IPv4 address/</tag> Set BIRD's router ID. It's a world-wide unique identification of your router, usually one of router's IPv4 addresses. Default: in IPv4 version, the lowest IP address of a non-loopback interface. In IPv6 version, this option is mandatory. 
+	<tag>router id <m/IPv4 address/</tag>
+ 	Set BIRD's router ID. It's a world-wide unique identification
+	of your router, usually one of router's IPv4 addresses.
+	Default: in IPv4 version, the lowest IP address of a
+	non-loopback interface. In IPv6 version, this option is
+	mandatory.
+
+	<tag>router id from [-] [ "<m/mask/" ] [ <m/prefix/ ] [, ...]</tag>
+	Set BIRD's router ID based on an IP address of an interface
+	specified by an interface pattern. The option is applicable
+	for IPv4 version only. See <ref id="dsc-iface" name="interface">
+	section for detailed description of interface patterns.
 
 	<tag>listen bgp [address <m/address/] [port <m/port/] [dual]</tag>
 	This option allows to specify address and port where BGP

nest/config.Y

@@ -75,9 +75,9 @@ CF_GRAMMAR
 
 CF_ADDTO(conf, rtrid)
 
-rtrid: ROUTER ID idval ';' {
-   new_config->router_id = $3;
-   }
+rtrid: 
+   ROUTER ID idval ';' { new_config->router_id = $3; }
+ | ROUTER ID FROM iface_patt ';' { new_config->router_id_from = this_ipatt; }
  ;
 
 idval:
@@ -264,6 +264,17 @@ iface_patt_list:
  | iface_patt_list ',' iface_patt_node
  ;
 
+iface_patt_init: {
+   /* Generic this_ipatt init */
+   this_ipatt = cfg_allocz(sizeof(struct iface_patt));
+   init_list(&this_ipatt->ipn_list);
+ }
+ ;
+
+iface_patt:
+   iface_patt_init iface_patt_list
+ ;
+
 
 /* Direct device route protocol */
 

nest/iface.c

@@ -35,8 +35,6 @@
 
 static pool *if_pool;
 
-static void auto_router_id(void);
-
 list iface_list;
 
 /**
@@ -354,9 +352,6 @@ if_end_update(void)
   struct iface *i;
   struct ifa *a, *b;
 
-  if (!config->router_id)
-    auto_router_id();
-
   WALK_LIST(i, iface_list)
     {
       if (!(i->flags & IF_UPDATED))
@@ -583,24 +578,57 @@ ifa_delete(struct ifa *a)
       }
 }
 
-static void
-auto_router_id(void)
+u32
+if_choose_router_id(struct iface_patt *mask, u32 old_id)
 {
 #ifndef IPV6
-  struct iface *i, *j;
+  struct iface *i;
+  struct ifa *a, *b;
 
-  j = NULL;
+  b = NULL;
   WALK_LIST(i, iface_list)
-    if ((i->flags & IF_ADMIN_UP) &&
-	!(i->flags & (IF_IGNORE | IF_SHUTDOWN)) &&
-	i->addr &&
-	!(i->addr->flags & IA_PEER) &&
-	(!j || ipa_to_u32(i->addr->ip) < ipa_to_u32(j->addr->ip)))
-      j = i;
-  if (!j)
-    die("Cannot determine router ID (no suitable network interface found), please configure it manually");
-  log(L_INFO "Guessed router ID %I according to interface %s", j->addr->ip, j->name);
-  config->router_id = ipa_to_u32(j->addr->ip);
+    {
+      if (!(i->flags & IF_ADMIN_UP) ||
+	  (i->flags & (IF_IGNORE | IF_SHUTDOWN)))
+	continue;
+
+      WALK_LIST(a, i->addrs)
+	{
+	  if (a->flags & IA_SECONDARY)
+	    continue;
+
+	  if (a->scope <= SCOPE_LINK)
+	    continue;
+
+	  /* FIXME: This should go away */
+	  if (a->flags & IA_PEER)
+	    continue;
+
+	  /* FIXME: This should go away too */
+	  if (!mask && (a != i->addr))
+	    continue;
+
+	  /* Check pattern if specified */
+	  if (mask && !iface_patt_match(mask, i, a))
+	    continue;
+
+	  /* No pattern or pattern matched */
+	  if (!b || ipa_to_u32(a->ip) < ipa_to_u32(b->ip))
+	    b = a;
+	}
+    }
+
+  if (!b)
+    return 0;
+
+  u32 id = ipa_to_u32(b->ip);
+  if (id != old_id)
+    log(L_INFO "Chosen router ID %R according to interface %s", id, b->iface->name);
+
+  return id;
+
+#else
+  return 0;
 #endif
 }
 

nest/iface.h

@@ -101,6 +101,7 @@ struct iface *if_find_by_name(char *);
 struct iface *if_get_by_name(char *);
 void ifa_recalc_all_primary_addresses(void);
 
+
 /* The Neighbor Cache */
 
 typedef struct neighbor {
@@ -161,4 +162,7 @@ int iface_patt_match(struct iface_patt *ifp, struct iface *i, struct ifa *a);
 struct iface_patt *iface_patt_find(list *l, struct iface *i, struct ifa *a);
 int iface_patts_equal(list *, list *, int (*)(struct iface_patt *, struct iface_patt *));
 
+
+u32 if_choose_router_id(struct iface_patt *mask, u32 old_id);
+
 #endif

nest/proto.c

@@ -382,11 +382,9 @@ proto_reconfigure(struct proto *p, struct proto_config *oc, struct proto_config
   /* If there is a too big change in core attributes, ... */
   if ((nc->protocol != oc->protocol) ||
       (nc->disabled != p->disabled) ||
-      (nc->table->table != oc->table->table) ||
-      (proto_get_router_id(nc) != proto_get_router_id(oc)))
+      (nc->table->table != oc->table->table))
     return 0;
 
-
   p->debug = nc->debug;
   p->mrtdump = nc->mrtdump;
   proto_reconfig_type = type;
@@ -552,6 +550,16 @@ protos_commit(struct config *new, struct config *old, int force_reconfig, int ty
     initial_device_proto = NULL;
   }
 
+  /* Determine router ID for the first time - it has to be here and not in
+     global_commit() because it is postponed after start of device protocol */
+  if (!config->router_id)
+    {
+      config->router_id = if_choose_router_id(config->router_id_from, 0);
+      if (!config->router_id)
+	die("Cannot determine router ID, please configure it manually");
+    }
+
+  /* Start all other protocols */
   WALK_LIST_DELSAFE(p, n, initial_proto_list)
     proto_rethink_goal(p);
 }

proto/bgp/bgp.c

@@ -1009,6 +1009,9 @@ bgp_reconfigure(struct proto *P, struct proto_config *C)
   struct bgp_proto *p = (struct bgp_proto *) P;
   struct bgp_config *old = p->cf;
 
+  if (proto_get_router_id(C) != p->local_id)
+    return 0;
+
   int same = !memcmp(((byte *) old) + sizeof(struct proto_config),
 		     ((byte *) new) + sizeof(struct proto_config),
 		     // password item is last and must be checked separately

proto/ospf/ospf.c

@@ -729,6 +729,9 @@ ospf_reconfigure(struct proto *p, struct proto_config *c)
   struct ospf_iface *ifa, *ifx;
   struct ospf_iface_patt *ip;
 
+  if (proto_get_router_id(c) != po->router_id)
+    return 0;
+
   if (po->rfc1583 != new->rfc1583)
     return 0;