From b29499996bbc1612a63a7e715bb53a8abf0940e3 Mon Sep 17 00:00:00 2001
From: "Ondrej Zajicek (work)" <santiago@crfreenet.org>
Date: Tue, 25 Apr 2017 19:02:31 +0200
Subject: [PATCH] Nest: Update of show route cmd

Some code cleanup, multiple bugfixes, allows to specify also channel
for 'show route export'. Interesting how such apparenty simple thing
like show route cmd has plenty of ugly corner cases.
---
 doc/bird.sgml   |  57 +++------
 nest/config.Y   |  51 ++++++--
 nest/proto.c    |  19 +++
 nest/protocol.h |   1 +
 nest/route.h    |  18 +--
 nest/rt-table.c | 314 ++++++++++++++++++++++++++++--------------------
 6 files changed, 272 insertions(+), 188 deletions(-)

diff --git a/doc/bird.sgml b/doc/bird.sgml
index 1777b8f3..0e072dd2 100644
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -924,13 +924,10 @@ This argument can be omitted if there exists only a single instance.
 	Show the list of symbols defined in the configuration (names of
 	protocols, routing tables etc.).
 
-	<tag><label id="cli-show-route">show route [[for] <m/prefix/|<m/IP/] [table (<m/t/ | all)] [filter <m/f/|where <m/c/] [(export|preexport|noexport) <m/p/] [protocol <m/p/] [(stats|count) [by table]] [<m/options/]</tag>
+	<tag><label id="cli-show-route">show route [[for] <m/prefix/|<m/IP/] [table (<m/t/ | all)] [filter <m/f/|where <m/c/] [(export|preexport|noexport) <m/p/] [protocol <m/p/] [(stats|count)] [<m/options/]</tag>
 	Show contents of specified routing tables, that is routes, their metrics
 	and (in case the <cf/all/ switch is given) all their attributes.
 
-	<p>More tables can be specified by repeating the <cf>table <m/t/></cf> clause.
-	To cycle over all tables, specify <cf>table all</cf>.
-
 	<p>You can specify a <m/prefix/ if you want to print routes for a
 	specific network. If you use <cf>for <m/prefix or IP/</cf>, you'll get
 	the entry which will be used for forwarding of packets to the given
@@ -938,57 +935,39 @@ This argument can be omitted if there exists only a single instance.
 	the selected one at the top, unless <cf/primary/ is given in which case
 	only the selected route is shown.
 
+	<p>The <cf/show route/ command can process one or multiple routing
+	tables. The set of selected tables is determined on three levels: First,
+	tables can be explicitly selected by <cf/table/ switch, which could be
+	used multiple times, all tables are specified by <cf/table all/. Second,
+	tables can be implicitly selected by channels or protocols that are
+	arguments of several other switches (e.g., <cf/export/, <cf/protocol/).
+	Last, the set of default tables is used: <cf/master4/, <cf/master6/ and
+	each first table of any other network type.
+
 	<p>You can also ask for printing only routes processed and accepted by
 	a given filter (<cf>filter <m/name/</cf> or <cf>filter { <m/filter/ }
 	</cf> or matching a given condition (<cf>where <m/condition/</cf>).
 
 	The <cf/export/, <cf/preexport/ and <cf/noexport/ switches ask for
-	printing of routes that are exported to the specified protocol.
-	With <cf/preexport/, the export filter of the protocol is skipped.
-	With <cf/noexport/, routes rejected by the export filter are printed
-	instead. Note that routes not exported to the protocol for other reasons
+	printing of routes that are exported to the specified protocol or
+	channel. With <cf/preexport/, the export filter of the channel is
+	skipped. With <cf/noexport/, routes rejected by the export filter are
+	printed instead. Note that routes not exported for other reasons
 	(e.g. secondary routes or routes imported from that protocol) are not
-	printed even with <cf/noexport/. These switches magically cycle over
-	all tables connected to the protocol.
+	printed even with <cf/noexport/. These switches also imply that
+	associated routing tables are selected instead of default ones.
 
 	<p>You can also select just routes added by a specific protocol.
-	<cf>protocol <m/p/</cf>. This switch also magically cycles over
-	all tables connected to the protocol.
+	<cf>protocol <m/p/</cf>. This switch also implies that associated
+	routing tables are selected instead of default ones.
 
 	<p>If BIRD is configured to keep filtered routes (see <cf/import keep
 	filtered/ option), you can show them instead of routes by using
 	<cf/filtered/ switch.
 
-	<p>If no table is specified in any way (<cf/table/, <cf/export/, <cf/preexport/, <cf/noexport/, <cf/protocol/),
-	the default tables are listed: <cf/master4/, <cf/master6/
-	and first declared table of any other net type.
-
 	<p>The <cf/stats/ switch requests showing of route statistics (the
 	number of networks, number of routes before and after filtering). If
 	you use <cf/count/ instead, only the statistics will be printed.
-	If you use <cf/stats by table/ or <cf/count by table/, the statistics
-	will be printed also per-table.
-
-	<tag><label id="cli-show-roa">show roa [<m/prefix/ | in <m/prefix/ | for <m/prefix/] [as <m/num/] [table <m/t/]</tag>
-	Show contents of a ROA table (by default of the first one). You can
-	specify a <m/prefix/ to print ROA entries for a specific network. If you
-	use <cf>for <m/prefix/</cf>, you'll get all entries relevant for route
-	validation of the network prefix; i.e., ROA entries whose prefixes cover
-	the network prefix. Or you can use <cf>in <m/prefix/</cf> to get ROA
-	entries covered by the network prefix. You could also use <cf/as/ option
-	to show just entries for given AS.
-
-	<tag><label id="cli-add-roa">add roa <m/prefix/ max <m/num/ as <m/num/ [table <m/t/]</tag>
-	Add a new ROA entry to a ROA table. Such entry is called <it/dynamic/
-	compared to <it/static/ entries specified in the config file. These
-	dynamic entries survive reconfiguration.
-
-	<tag><label id="cli-delete-roa">delete roa <m/prefix/ max <m/num/ as <m/num/ [table <m/t/]</tag>
-	Delete the specified ROA entry from a ROA table. Only dynamic ROA
-	entries (i.e., the ones added by <cf/add roa/ command) can be deleted.
-
-	<tag><label id="cli-flush-roa">flush roa [table <m/t/]</tag>
-	Remove all dynamic ROA entries from a ROA table.
 
 	<tag><label id="cli-configure">configure [soft] ["<m/config file/"] [timeout [<m/num/]]</tag>
 	Reload configuration from a given file. BIRD will smoothly switch itself
diff --git a/nest/config.Y b/nest/config.Y
index 0b34fb24..b0f9642f 100644
--- a/nest/config.Y
+++ b/nest/config.Y
@@ -75,6 +75,9 @@ CF_KEYWORDS(LISTEN, BGP, V6ONLY, DUAL, ADDRESS, PORT, PASSWORDS, DESCRIPTION, SO
 CF_KEYWORDS(RELOAD, IN, OUT, MRTDUMP, MESSAGES, RESTRICT, MEMORY, IGP_METRIC, CLASS, DSCP)
 CF_KEYWORDS(GRACEFUL, RESTART, WAIT, MAX, FLUSH, AS)
 
+/* For r_args_channel */
+CF_KEYWORDS(IPV4, IPV4_MC, IPV4_MPLS, IPV6, IPV6_MC, IPV6_MPLS, VPN4, VPN4_MC, VPN4_MPLS, VPN6, VPN6_MC, VPN6_MPLS, ROA4, ROA6, FLOW4, FLOW6, MPLS, PRI, SEC)
+
 CF_ENUM(T_ENUM_RTS, RTS_, DUMMY, STATIC, INHERIT, DEVICE, STATIC_DEVICE, REDIRECT,
 	RIP, OSPF, OSPF_IA, OSPF_EXT1, OSPF_EXT2, BGP, PIPE, BABEL)
 CF_ENUM(T_ENUM_SCOPE, SCOPE_, HOST, LINK, SITE, ORGANIZATION, UNIVERSE, UNDEFINED)
@@ -93,6 +96,7 @@ CF_ENUM(T_ENUM_ROA, ROA_, UNKNOWN, VALID, INVALID)
 %type <cl> limit_spec
 %type <net> r_args_for_val
 %type <net_ptr> r_args_for
+%type <t> r_args_channel
 
 CF_GRAMMAR
 
@@ -514,7 +518,7 @@ CF_CLI(SHOW ROUTE, r_args, [[[<prefix>|for <prefix>|for <ip>] [table <t>] [filte
 r_args:
    /* empty */ {
      $$ = cfg_allocz(sizeof(struct rt_show_data));
-     init_list(&($$->table));
+     init_list(&($$->tables));
      $$->filter = FILTER_ACCEPT;
    }
  | r_args net_any {
@@ -566,13 +570,24 @@ r_args:
  | r_args export_mode SYM {
      struct proto_config *c = (struct proto_config *) $3->def;
      $$ = $1;
-     if ($$->export_mode) cf_error("Protocol specified twice");
+     if ($$->export_mode) cf_error("Export specified twice");
      if ($3->class != SYM_PROTO || !c->proto) cf_error("%s is not a protocol", $3->name);
      $$->export_mode = $2;
      $$->export_protocol = c->proto;
      $$->running_on_config = c->proto->cf->global;
      $$->tables_defined_by = RSD_TDB_INDIRECT;
    }
+ | r_args export_mode SYM '.' r_args_channel {
+     struct proto_config *c = (struct proto_config *) $3->def;
+     $$ = $1;
+     if ($$->export_mode) cf_error("Export specified twice");
+     if ($3->class != SYM_PROTO || !c->proto) cf_error("%s is not a protocol", $3->name);
+     $$->export_mode = $2;
+     $$->export_channel = proto_find_channel_by_name(c->proto, $5);
+     if (!$$->export_channel) cf_error("Export channel not found");
+     $$->running_on_config = c->proto->cf->global;
+     $$->tables_defined_by = RSD_TDB_INDIRECT;
+   }
  | r_args PROTOCOL SYM {
      struct proto_config *c = (struct proto_config *) $3->def;
      $$ = $1;
@@ -590,16 +605,6 @@ r_args:
      $$ = $1;
      $$->stats = 2;
    }
- | r_args STATS BY TABLE {
-     $$ = $1;
-     $$->stats = 1;
-     $$->stats_by_table = 1;
-   }
- | r_args COUNT BY TABLE {
-     $$ = $1;
-     $$->stats = 2;
-     $$->stats_by_table = 1;
-   }
  ;
 
 r_args_for:
@@ -642,6 +647,28 @@ export_mode:
  | NOEXPORT	{ $$ = RSEM_NOEXPORT; }
  ;
 
+/* This is ugly hack */
+r_args_channel:
+   IPV4		{ $$ = "ipv4"; }
+ | IPV4_MC	{ $$ = "ipv4-mc"; }
+ | IPV4_MPLS	{ $$ = "ipv4-mpls"; }
+ | IPV6		{ $$ = "ipv6"; }
+ | IPV6_MC	{ $$ = "ipv6-mc"; }
+ | IPV6_MPLS	{ $$ = "ipv6-mpls"; }
+ | VPN4		{ $$ = "vpn4"; }
+ | VPN4_MC	{ $$ = "vpn4-mc"; }
+ | VPN4_MPLS	{ $$ = "vpn4-mpls"; }
+ | VPN6		{ $$ = "vpn6"; }
+ | VPN6_MC	{ $$ = "vpn6-mc"; }
+ | VPN6_MPLS	{ $$ = "vpn6-mpls"; }
+ | ROA4		{ $$ = "roa4"; }
+ | ROA6		{ $$ = "roa6"; }
+ | FLOW4	{ $$ = "flow4"; }
+ | FLOW6	{ $$ = "flow6"; }
+ | MPLS		{ $$ = "mpls"; }
+ | PRI		{ $$ = "pri"; }
+ | SEC		{ $$ = "sec"; }
+ ;
 
 CF_CLI_HELP(SHOW SYMBOLS, ..., [[Show all known symbolic names]])
 CF_CLI(SHOW SYMBOLS, sym_args, [table|filter|function|protocol|template|<symbol>], [[Show all known symbolic names]])
diff --git a/nest/proto.c b/nest/proto.c
index 0a7a32a6..3d764df0 100644
--- a/nest/proto.c
+++ b/nest/proto.c
@@ -104,6 +104,25 @@ proto_find_channel_by_table(struct proto *p, struct rtable *t)
   return NULL;
 }
 
+/**
+ * proto_find_channel_by_name - find channel by its name
+ * @p: protocol instance
+ * @n: channel name
+ *
+ * Returns pointer to channel or NULL
+ */
+struct channel *
+proto_find_channel_by_name(struct proto *p, const char *n)
+{
+  struct channel *c;
+
+  WALK_LIST(c, p->channels)
+    if (!strcmp(c->name, n))
+      return c;
+
+  return NULL;
+}
+
 /**
  * proto_add_channel - connect protocol to a routing table
  * @p: protocol instance
diff --git a/nest/protocol.h b/nest/protocol.h
index 6efaaaf7..f0958678 100644
--- a/nest/protocol.h
+++ b/nest/protocol.h
@@ -563,6 +563,7 @@ static inline struct channel_config *proto_cf_main_channel(struct proto_config *
 { struct channel_config *cc = HEAD(pc->channels); return NODE_VALID(cc) ? cc : NULL; }
 
 struct channel *proto_find_channel_by_table(struct proto *p, struct rtable *t);
+struct channel *proto_find_channel_by_name(struct proto *p, const char *n);
 struct channel *proto_add_channel(struct proto *p, struct channel_config *cf);
 int proto_configure_channel(struct proto *p, struct channel **c, struct channel_config *cf);
 
diff --git a/nest/route.h b/nest/route.h
index 12968cb8..6c9b00c2 100644
--- a/nest/route.h
+++ b/nest/route.h
@@ -313,26 +313,30 @@ struct rtable_config *rt_new_table(struct symbol *s, uint addr_type);
 struct rt_show_data_rtable {
   node n;
   rtable *table;
+  struct channel *export_channel;
 };
 
 struct rt_show_data {
   net_addr *addr;
-  list table;
-  struct rt_show_data_rtable *tit;
-  struct filter *filter;
+  list tables;
+  struct rt_show_data_rtable *tab;	/* Iterator over table list */
+  struct rt_show_data_rtable *last_table; /* Last table in output */
+  struct fib_iterator fit;		/* Iterator over networks in table */
   int verbose, tables_defined_by;
-  struct fib_iterator fit;
+  struct filter *filter;
   struct proto *show_protocol;
   struct proto *export_protocol;
   struct channel *export_channel;
-  int export_mode, primary_only, filtered;
   struct config *running_on_config;
+  int export_mode, primary_only, filtered, stats, show_for;
+
+  int table_open;			/* Iteration (fit) is open */
   int net_counter, rt_counter, show_counter, table_counter;
   int net_counter_last, rt_counter_last, show_counter_last;
-  int stats, show_for, stats_by_table;
 };
+
 void rt_show(struct rt_show_data *);
-void rt_show_add_table(struct rt_show_data *d, rtable *t);
+struct rt_show_data_rtable * rt_show_add_table(struct rt_show_data *d, rtable *t);
 
 /* Value of table definition mode in struct rt_show_data */
 #define RSD_TDB_DEFAULT	  0		/* no table specified */
diff --git a/nest/rt-table.c b/nest/rt-table.c
index be764313..67ccc885 100644
--- a/nest/rt-table.c
+++ b/nest/rt-table.c
@@ -2503,6 +2503,18 @@ rt_get_hostentry(rtable *tab, ip_addr a, ip_addr ll, rtable *dep)
  *  CLI commands
  */
 
+static void
+rt_show_table(struct cli *c, struct rt_show_data *d)
+{
+  /* No table blocks in 'show route count' */
+  if (d->stats == 2)
+    return;
+
+  if (d->last_table) cli_printf(c, -1007, "");
+  cli_printf(c, -1007, "Table %s:", d->tab->table->name);
+  d->last_table = d->tab;
+}
+
 static void
 rt_show_rte(struct cli *c, byte *ia, rte *e, struct rt_show_data *d, ea_list *tmpa)
 {
@@ -2535,8 +2547,8 @@ rt_show_rte(struct cli *c, byte *ia, rte *e, struct rt_show_data *d, ea_list *tm
   else
     bsprintf(info, " (%d)", e->pref);
 
-  if (!d->show_counter)
-    cli_printf(c, -1007, "Table %s:", d->tit->table->name);
+  if (d->last_table != d->tab)
+    rt_show_table(c, d);
 
   cli_printf(c, -1007, "%-18s %s [%s %s%s]%s%s", ia, rta_dest_name(a->dest),
 	     a->src->proto->name, tm, from, primary ? (sync_error ? " !" : " *") : "", info);
@@ -2570,7 +2582,7 @@ rt_show_net(struct cli *c, net *n, struct rt_show_data *d)
   rte *e, *ee;
   byte ia[NET_MAX_TEXT_LENGTH+1];
   struct ea_list *tmpa;
-  struct channel *ec = d->export_channel;
+  struct channel *ec = d->tab->export_channel;
   int first = 1;
   int pass = 0;
 
@@ -2592,6 +2604,10 @@ rt_show_net(struct cli *c, net *n, struct rt_show_data *d)
       rte_update_lock();		/* We use the update buffer for filtering */
       tmpa = make_tmp_attrs(e, rte_update_pool);
 
+      /* Export channel is down, do not try to export routes to it */
+      if (ec && (ec->export_state == ES_DOWN))
+	goto skip;
+
       /* Special case for merged export */
       if ((d->export_mode == RSEM_EXPORT) && (ec->ra_mode == RA_MERGED))
         {
@@ -2604,7 +2620,7 @@ rt_show_net(struct cli *c, net *n, struct rt_show_data *d)
 	}
       else if (d->export_mode)
 	{
-	  struct proto *ep = d->export_protocol;
+	  struct proto *ep = ec->proto;
 	  int ic = ep->import_control ? ep->import_control(ep, &e, &tmpa, rte_update_pool) : 0;
 
 	  if (ec->ra_mode == RA_OPTIMAL || ec->ra_mode == RA_MERGED)
@@ -2656,25 +2672,19 @@ rt_show_net(struct cli *c, net *n, struct rt_show_data *d)
     }
 }
 
-static struct channel *
-rt_show_export_channel(struct rt_show_data *d)
-{
-  if (! d->export_protocol->rt_notify)
-    return NULL;
-
-  return proto_find_channel_by_table(d->export_protocol, d->tit->table);
-}
-
 static void
 rt_show_cleanup(struct cli *c)
 {
   struct rt_show_data *d = c->rover;
+  struct rt_show_data_rtable *tab;
 
   /* Unlink the iterator */
-  fit_get(&d->tit->table->fib, &d->fit);
-  rt_unlock_table(d->tit->table);
-  while (NODE_VALID(NODE_NEXT(d->tit)))
-    rt_unlock_table((d->tit = NODE_NEXT(d->tit))->table);
+  if (d->table_open)
+    fit_get(&d->tab->table->fib, &d->fit);
+
+  /* Unlock referenced tables */
+  WALK_LIST(tab, d->tables)
+    rt_unlock_table(tab->table);
 }
 
 static void
@@ -2686,84 +2696,110 @@ rt_show_cont(struct cli *c)
 #else
   unsigned max = 64;
 #endif
-  struct fib *fib = &d->tit->table->fib;
+  struct fib *fib = &d->tab->table->fib;
   struct fib_iterator *it = &d->fit;
 
-  if (d->export_mode)
-    {
-      /* Ensure we have current export channel */
-      d->export_channel = rt_show_export_channel(d);
-      if (!d->export_channel || (d->export_channel->export_state == ES_DOWN))
-        {
-	  cli_printf(c, 8005, "Channel is down");
-	  rt_show_cleanup(c);
-	  goto done;
-	}
-    }
+  if (d->running_on_config && (d->running_on_config != config))
+  {
+    cli_printf(c, 8004, "Stopped due to reconfiguration");
+    goto done;
+  }
+
+  if (!d->table_open)
+  {
+    FIB_ITERATE_INIT(&d->fit, &d->tab->table->fib);
+    d->table_open = 1;
+    d->table_counter++;
+
+    d->show_counter_last = d->show_counter;
+    d->rt_counter_last   = d->rt_counter;
+    d->net_counter_last  = d->net_counter;
+
+    if (d->tables_defined_by & RSD_TDB_SET)
+      rt_show_table(c, d);
+  }
 
   FIB_ITERATE_START(fib, it, net, n)
+  {
+    if (!max--)
     {
-      if (!max--)
-	{
-	  FIB_ITERATE_PUT(it);
-	  return;
-	}
-      rt_show_net(c, n, d);
-    }
-  FIB_ITERATE_END;
-
-  if (!d->show_counter && (d->tables_defined_by & RSD_TDB_SET))
-    cli_printf(c, -1007, "Table %s:", d->tit->table->name);
-
-  if (d->stats && d->stats_by_table)
-    cli_printf(c, -1007, "%d of %d routes for %d networks in table %s", d->show_counter - d->show_counter_last, d->rt_counter - d->rt_counter_last, d->net_counter - d->net_counter_last, d->tit->table->name);
-
-  rt_unlock_table(d->tit->table);
-  d->table_counter++;
-  if (NODE_VALID(NODE_NEXT(d->tit)))
-    {
-      d->tit = NODE_NEXT(d->tit);
-      FIB_ITERATE_INIT(&d->fit, &d->tit->table->fib);
-      d->show_counter_last = d->show_counter;
-      d->rt_counter_last = d->rt_counter;
-      d->net_counter_last = d->net_counter;
-      d->show_counter = 0;
-      d->rt_counter = 0;
-      d->net_counter = 0;
+      FIB_ITERATE_PUT(it);
       return;
     }
+    rt_show_net(c, n, d);
+  }
+  FIB_ITERATE_END;
 
   if (d->stats)
-    cli_printf(c, 14, "Total: %d of %d routes for %d networks in %d tables", d->show_counter, d->rt_counter, d->net_counter, d->table_counter);
+  {
+    if (d->last_table != d->tab)
+      rt_show_table(c, d);
+
+    cli_printf(c, -1007, "%d of %d routes for %d networks in table %s",
+	       d->show_counter - d->show_counter_last, d->rt_counter - d->rt_counter_last,
+	       d->net_counter - d->net_counter_last, d->tab->table->name);
+  }
+
+  d->table_open = 0;
+  d->tab = NODE_NEXT(d->tab);
+
+  if (NODE_VALID(d->tab))
+    return;
+
+  if (d->stats && (d->table_counter > 1))
+  {
+    if (d->last_table) cli_printf(c, -1007, "");
+    cli_printf(c, 14, "Total: %d of %d routes for %d networks in %d tables",
+	       d->show_counter, d->rt_counter, d->net_counter, d->table_counter);
+  }
   else
     cli_printf(c, 0, "");
+
 done:
+  rt_show_cleanup(c);
   c->cont = c->cleanup = NULL;
 }
 
-void rt_show_add_table(struct rt_show_data *d, rtable *t)
+struct rt_show_data_rtable *
+rt_show_add_table(struct rt_show_data *d, rtable *t)
 {
-  struct rt_show_data_rtable *rsdr = cfg_alloc(sizeof(struct rt_show_data_rtable));
-  rsdr->table = t;
-  add_tail(&(d->table), &(rsdr->n));
+  struct rt_show_data_rtable *tab = cfg_allocz(sizeof(struct rt_show_data_rtable));
+  tab->table = t;
+  add_tail(&(d->tables), &(tab->n));
+  return tab;
 }
 
 static inline void
-rt_show_get_table(struct proto *p, struct rt_show_data *d)
+rt_show_get_default_tables(struct rt_show_data *d)
 {
   struct channel *c;
-  WALK_LIST(c, p->channels)
-    if (c->table)
-      rt_show_add_table(d, c->table);
+  struct rt_show_data_rtable *tab;
 
-}
-
-static inline void
-rt_show_get_default_table(struct rt_show_data *d)
-{
-  if (d->export_protocol || d->show_protocol)
+  if (d->export_channel)
   {
-    rt_show_get_table(d->export_protocol ?: d->show_protocol, d);
+    c = d->export_channel;
+    tab = rt_show_add_table(d, c->table);
+    tab->export_channel = c;
+    return;
+  }
+
+  if (d->export_protocol)
+  {
+    WALK_LIST(c, d->export_protocol->channels)
+    {
+      if (c->export_state == ES_DOWN)
+	continue;
+
+      tab = rt_show_add_table(d, c->table);
+      tab->export_channel = c;
+    }
+    return;
+  }
+
+  if (d->show_protocol)
+  {
+    WALK_LIST(c, d->show_protocol->channels)
+      rt_show_add_table(d, c->table);
     return;
   }
 
@@ -2772,78 +2808,96 @@ rt_show_get_default_table(struct rt_show_data *d)
       rt_show_add_table(d, config->def_tables[i]->table);
 }
 
+static inline void
+rt_show_prepare_tables(struct rt_show_data *d)
+{
+  struct rt_show_data_rtable *tab, *tabx;
+
+  /* Add implicit tables if no table is specified */
+  if (EMPTY_LIST(d->tables))
+    rt_show_get_default_tables(d);
+
+  WALK_LIST_DELSAFE(tab, tabx, d->tables)
+  {
+    /* Ensure there is defined export_channel for each table */
+    if (d->export_mode)
+    {
+      if (!tab->export_channel && d->export_channel &&
+	  (tab->table == d->export_channel->table))
+	tab->export_channel = d->export_channel;
+
+      if (!tab->export_channel && d->export_protocol)
+	tab->export_channel = proto_find_channel_by_table(d->export_protocol, tab->table);
+
+      if (!tab->export_channel)
+      {
+	if (d->tables_defined_by & RSD_TDB_NMN)
+	  cf_error("No export channel for table %s", tab->table->name);
+
+	rem_node(&(tab->n));
+	continue;
+      }
+    }
+
+    /* Ensure specified network is compatible with each table */
+    if (d->addr && (tab->table->addr_type != d->addr->type))
+    {
+      if (d->tables_defined_by & RSD_TDB_NMN)
+	cf_error("Incompatible type of prefix/ip for table %s", tab->table->name);
+
+      rem_node(&(tab->n));
+      continue;
+    }
+  }
+
+  /* Ensure there is at least one table */
+  if (EMPTY_LIST(d->tables))
+    cf_error("No valid tables");
+}
+
 void
 rt_show(struct rt_show_data *d)
 {
+  struct rt_show_data_rtable *tab;
   net *n;
 
-  /* There may be implicit tables. */
-  if (EMPTY_LIST(d->table)) rt_show_get_default_table(d);
-
   /* Filtered routes are neither exported nor have sensible ordering */
   if (d->filtered && (d->export_mode || d->primary_only))
-    cli_msg(0, "");
+    cf_error("Incompatible show route options");
+
+  rt_show_prepare_tables(d);
 
   if (!d->addr)
-    {
-      struct rt_show_data_rtable *rsdr;
-      WALK_LIST(rsdr, d->table)
-      {
-	rt_lock_table(rsdr->table);
-      }
-      d->tit = HEAD(d->table);
-      FIB_ITERATE_INIT(&d->fit, &d->tit->table->fib);
-      this_cli->cont = rt_show_cont;
-      this_cli->cleanup = rt_show_cleanup;
-      this_cli->rover = d;
-    }
+  {
+    WALK_LIST(tab, d->tables)
+      rt_lock_table(tab->table);
+
+    /* There is at least one table */
+    d->tab = HEAD(d->tables);
+    this_cli->cont = rt_show_cont;
+    this_cli->cleanup = rt_show_cleanup;
+    this_cli->rover = d;
+  }
   else
+  {
+    WALK_LIST(tab, d->tables)
     {
-      if (d->export_mode)
-        {
-	  /* Find channel associated with the export protocol */
-	  d->export_channel = rt_show_export_channel(d);
-	  if (!d->export_channel || (d->export_channel->export_state == ES_DOWN))
-	    {
-	      cli_msg(8005, "Channel is down");
-	      return;
-	    }
-	}
+      d->tab = tab;
 
-      struct rt_show_data_rtable *rsdr, *rn;
-      WALK_LIST_DELSAFE(rsdr, rn, d->table)
-      {
-	/* Check table net types matching to query */
-	if (rsdr->table->addr_type == d->addr->type)
-	  continue;
-
-	if (d->tables_defined_by & RSD_TDB_NMN)
-	{
-	  cli_msg(8001, "Incompatible type of prefix/ip with table %s", rsdr->table->name);
-	  return;
-	}
-
-	rem_node(&(rsdr->n));
-      }
-
-      WALK_LIST(rsdr, d->table)
-      {
-	d->tit = rsdr;
-
-	if (d->show_for)
-	  n = net_route(rsdr->table, d->addr);
-	else
-	  n = net_find(rsdr->table, d->addr);
-
-	if (n)
-	  rt_show_net(this_cli, n, d);
-      }
-
-      if (d->rt_counter)
-	cli_msg(0, "");
+      if (d->show_for)
+	n = net_route(tab->table, d->addr);
       else
-	cli_msg(8001, "Network not found in any specified table");
+	n = net_find(tab->table, d->addr);
+
+      if (n)
+	rt_show_net(this_cli, n, d);
     }
+
+    if (d->rt_counter)
+      cli_msg(0, "");
+    else
+      cli_msg(8001, "Network not found");
+  }
 }
 
 /*