/*
 *	BIRD -- Table-to-Table Routing Protocol a.k.a Pipe
 *
 *	(c) 1999--2000 Martin Mares <mj@ucw.cz>
 *
 *	Can be freely distributed and used under the terms of the GNU GPL.
 */

/**
 * DOC: Pipe
 *
 * The Pipe protocol is very simple. It just connects to two routing tables
 * using proto_add_announce_hook() and whenever it receives a rt_notify()
 * about a change in one of the tables, it converts it to a rte_update()
 * in the other one.
 *
 * To avoid pipe loops, Pipe keeps a `being updated' flag in each routing
 * table.
 *
 * A pipe has two announce hooks, the first connected to the main
 * table, the second connected to the peer table. When a new route is
 * announced on the main table, it gets checked by an export filter in
 * ahook 1, and, after that, it is announced to the peer table via
 * rte_update(), an import filter in ahook 2 is called. When a new
 * route is announced in the peer table, an export filter in ahook2
 * and an import filter in ahook 1 are used. Oviously, there is no
 * need in filtering the same route twice, so both import filters are
 * set to accept, while user configured 'import' and 'export' filters
 * are used as export filters in ahooks 2 and 1. Route limits are
 * handled similarly, but on the import side of ahooks.
 */

#undef LOCAL_DEBUG

#include "nest/bird.h"
#include "nest/iface.h"
#include "nest/protocol.h"
#include "nest/route.h"
#include "nest/cli.h"
#include "conf/conf.h"
#include "filter/filter.h"
#include "lib/string.h"

#include "pipe.h"

static void
pipe_rt_notify(struct proto *P, struct channel *src_ch, const net_addr *n, rte *new, const rte *old)
{
  struct pipe_proto *p = (void *) P;
  struct channel *dst = (src_ch == p->pri) ? p->sec : p->pri;

  /* Reject everything on shutdown */
  if (SHUTTING_DOWN)
    return;

  if (!new && !old)
    return;

  if (new)
    {
      rte e0 = rte_init_from(new);

      e0.generation = new->generation + 1;
      ea_unset_attr(&e0.attrs, 0, &ea_gen_hostentry);

      rte_update(dst, n, &e0, new->src);
    }
  else
    rte_update(dst, n, NULL, old->src);
}

static int
pipe_preexport(struct channel *C, rte *e)
{
  struct pipe_proto *p = (void *) C->proto;

  /* Reject everything on shutdown */
  if (SHUTTING_DOWN)
    return -1;

  /* Avoid direct loopbacks */
  if (e->sender == C->in_req.hook)
    return -1;

  /* Indirection check */
  uint max_generation = ((struct pipe_config *) p->p.cf)->max_generation;
  if (e->generation >= max_generation)
  {
    log_rl(&p->rl_gen, L_ERR "Route overpiped (%u hops of %u configured in %s) in table %s: %N %s/%u:%u",
	e->generation, max_generation, C->proto->name,
	C->table->name, e->net, e->src->owner->name, e->src->private_id, e->src->global_id);

    return -1;
  }

  return 0;
}

static int
pipe_reload_routes(struct channel *C, struct rt_feeding_request *rfr)
{
  SKIP_BACK_DECLARE(struct pipe_proto, p, p, C->proto);
  rt_export_refeed(&((C == p->pri) ? p->sec : p->pri)->out_req, rfr);
  return 1;
}

static void
pipe_postconfig(struct proto_config *CF)
{
  struct pipe_config *cf = (void *) CF;
  struct channel_config *cc = proto_cf_main_channel(CF);

  if (!cc->table)
    cf_error("Primary routing table not specified");

  if (!cf->peer)
    cf_error("Secondary routing table not specified");

  if (cc->table == cf->peer)
    cf_error("Primary table and peer table must be different");

  if (cc->table->addr_type != cf->peer->addr_type)
    cf_error("Primary table and peer table must have the same type");

  if (cc->out_subprefix && (cc->table->addr_type != cc->out_subprefix->type))
    cf_error("Export subprefix must match table type");

  if (cf->in_subprefix && (cc->table->addr_type != cf->in_subprefix->type))
    cf_error("Import subprefix must match table type");

  if (cc->rx_limit.action)
    cf_error("Pipe protocol does not support receive limits");

  if (cc->in_keep)
    cf_error("Pipe protocol prohibits keeping filtered routes");

  cc->debug = cf->c.debug;
}

static int
pipe_configure_channels(struct pipe_proto *p, struct pipe_config *cf)
{
  struct channel_config *cc = proto_cf_main_channel(&cf->c);

  struct channel_config pri_cf = {
    .name = "pri",
    .class = cc->class,
    .table = cc->table,
    .out_filter = cc->out_filter,
    .out_subprefix = cc->out_subprefix,
    .in_limit = cc->in_limit,
    .ra_mode = RA_ANY,
    .debug = cc->debug,
    .rpki_reload = cc->rpki_reload,
  };

  struct channel_config sec_cf = {
    .name = "sec",
    .class = cc->class,
    .table = cf->peer,
    .out_filter = cc->in_filter,
    .out_subprefix = cf->in_subprefix,
    .in_limit = cc->out_limit,
    .ra_mode = RA_ANY,
    .debug = cc->debug,
    .rpki_reload = cc->rpki_reload,
  };

  return
    proto_configure_channel(&p->p, &p->pri, &pri_cf) &&
    proto_configure_channel(&p->p, &p->sec, &sec_cf);
}

static struct proto *
pipe_init(struct proto_config *CF)
{
  struct proto *P = proto_new(CF);
  struct pipe_proto *p = (void *) P;
  struct pipe_config *cf = (void *) CF;

  P->rt_notify = pipe_rt_notify;
  P->preexport = pipe_preexport;
  P->reload_routes = pipe_reload_routes;

  p->rl_gen = (struct tbf) TBF_DEFAULT_LOG_LIMITS;

  pipe_configure_channels(p, cf);

  return P;
}

static int
pipe_reconfigure(struct proto *P, struct proto_config *CF)
{
  struct pipe_proto *p = (void *) P;
  struct pipe_config *cf = (void *) CF;

  return pipe_configure_channels(p, cf);
}

static void
pipe_copy_config(struct proto_config *dest UNUSED, struct proto_config *src UNUSED)
{
  /* Just a shallow copy, not many items here */
}

static void
pipe_get_status(struct proto *P, byte *buf)
{
  struct pipe_proto *p = (void *) P;

  bsprintf(buf, "%s <=> %s", p->pri->table->name, p->sec->table->name);
}

static void
pipe_show_stats(struct pipe_proto *p)
{
  struct channel_import_stats *s1i = &p->pri->import_stats;
  struct channel_export_stats *s1e = &p->pri->export_stats;
  struct channel_import_stats *s2i = &p->sec->import_stats;
  struct channel_export_stats *s2e = &p->sec->export_stats;

  struct rt_import_stats *rs1i = p->pri->in_req.hook ? &p->pri->in_req.hook->stats : NULL;
  struct rt_export_stats *rs1e = &p->pri->out_req.stats;
  struct rt_import_stats *rs2i = p->sec->in_req.hook ? &p->sec->in_req.hook->stats : NULL;
  struct rt_export_stats *rs2e = &p->sec->out_req.stats;

  u32 pri_routes = p->pri->in_limit.count;
  u32 sec_routes = p->sec->in_limit.count;

  /*
   * Pipe stats (as anything related to pipes) are a bit tricky. There
   * are two sets of stats - s1 for ahook to the primary routing and
   * s2 for the ahook to the secondary routing table. The user point
   * of view is that routes going from the primary routing table to
   * the secondary routing table are 'exported', while routes going in
   * the other direction are 'imported'.
   *
   * Each route going through a pipe is, technically, first exported
   * to the pipe and then imported from that pipe and such operations
   * are counted in one set of stats according to the direction of the
   * route propagation. Filtering is done just in the first part
   * (export). Therefore, we compose stats for one directon for one
   * user direction from both import and export stats, skipping
   * immediate and irrelevant steps (exp_updates_accepted,
   * imp_updates_received, imp_updates_filtered, ...).
   *
   * Rule of thumb is that stats s1 have the correct 'polarity'
   * (imp/exp), while stats s2 have switched 'polarity'.
   */

  cli_msg(-1006, "  Routes:         %u imported, %u exported",
	  pri_routes, sec_routes);
  cli_msg(-1006, "  Route change stats:     received   rejected   filtered    ignored   accepted");
  cli_msg(-1006, "    Import updates:     %10u %10u %10u %10u %10u",
	  rs2e->updates_received, s2e->updates_rejected + s1i->updates_invalid,
	  s2e->updates_filtered, rs1i->updates_ignored, rs1i->updates_accepted);
  cli_msg(-1006, "    Import withdraws:   %10u %10u        --- %10u %10u",
	  rs2e->withdraws_received, s1i->withdraws_invalid,
	  rs1i->withdraws_ignored, rs1i->withdraws_accepted);
  cli_msg(-1006, "    Export updates:     %10u %10u %10u %10u %10u",
	  rs1e->updates_received, s1e->updates_rejected + s2i->updates_invalid,
	  s1e->updates_filtered, rs2i->updates_ignored, rs2i->updates_accepted);
  cli_msg(-1006, "    Export withdraws:   %10u %10u        --- %10u %10u",
	  rs1e->withdraws_received, s2i->withdraws_invalid,
	  rs2i->withdraws_ignored, rs2i->withdraws_accepted);
}

static void
pipe_show_proto_info(struct proto *P)
{
  struct pipe_proto *p = (void *) P;

  cli_msg(-1006, "  Channel %s", "main");
  cli_msg(-1006, "    Table:          %s", p->pri->table->name);
  cli_msg(-1006, "    Peer table:     %s", p->sec->table->name);
  cli_msg(-1006, "    Import state:   %s", rt_export_state_name(rt_export_get_state(&p->sec->out_req)));
  cli_msg(-1006, "    Export state:   %s", rt_export_state_name(rt_export_get_state(&p->pri->out_req)));
  cli_msg(-1006, "    Import filter:  %s", filter_name(p->sec->out_filter));
  cli_msg(-1006, "    Export filter:  %s", filter_name(p->pri->out_filter));



  channel_show_limit(&p->pri->in_limit, "Import limit:",
      (p->pri->limit_active & (1 << PLD_IN)), p->pri->limit_actions[PLD_IN]);
  channel_show_limit(&p->sec->in_limit, "Export limit:",
      (p->sec->limit_active & (1 << PLD_IN)), p->sec->limit_actions[PLD_IN]);

  if (P->proto_state == PS_UP)
    pipe_show_stats(p);
}

void
pipe_update_debug(struct proto *P)
{
  struct pipe_proto *p = (void *) P;

  p->pri->debug = p->sec->debug = p->p.debug;
}


struct protocol proto_pipe = {
  .name =		"Pipe",
  .template =		"pipe%d",
  .proto_size =		sizeof(struct pipe_proto),
  .config_size =	sizeof(struct pipe_config),
  .startup =		PROTOCOL_STARTUP_CONNECTOR,
  .postconfig =		pipe_postconfig,
  .init =		pipe_init,
  .reconfigure =	pipe_reconfigure,
  .copy_config = 	pipe_copy_config,
  .get_status = 	pipe_get_status,
  .show_proto_info = 	pipe_show_proto_info
};

void
pipe_build(void)
{
  proto_build(&proto_pipe);
}