/*

  server_backup.c 

  Author: Pekka Riikonen <priikone@silcnet.org>

  Copyright (C) 2001 - 2002 Pekka Riikonen

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; version 2 of the License.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

*/
/* $Id$ */

#include "serverincludes.h"
#include "server_internal.h"

SILC_TASK_CALLBACK(silc_server_protocol_backup_done);
static void silc_server_backup_connect_primary(SilcServer server,
					       SilcServerEntry server_entry,
					       void *context);

/* Backup router */
typedef struct {
  SilcServerEntry server;
  SilcIDIP ip;
  SilcUInt16 port;
  bool local;
} SilcServerBackupEntry;

/* Holds IP address and port of the primary router that was replaced
   by backup router. */
typedef struct {
  SilcIDIP ip;
  SilcUInt16 port;
  SilcServerEntry server;	/* Backup router that replaced the primary */
} SilcServerBackupReplaced;

/* Backup context */
struct SilcServerBackupStruct {
  SilcServerBackupEntry *servers;
  SilcUInt32 servers_count;
  SilcServerBackupReplaced **replaced;
  SilcUInt32 replaced_count;
};

typedef struct {
  SilcUInt8 session;
  bool connected;
  SilcServerEntry server_entry;
} SilcServerBackupProtocolSession;

/* Backup resuming protocol context  */
typedef struct {
  SilcServer server;
  SilcSocketConnection sock;
  bool responder;
  SilcUInt8 type;
  SilcUInt8 session;
  SilcServerBackupProtocolSession *sessions;
  SilcUInt32 sessions_count;
  long start;
} *SilcServerBackupProtocolContext;

/* Adds the `backup_server' to be one of our backup router. This can be
   called multiple times to set multiple backup routers. The `ip' and `port'
   is the IP and port that the `backup_router' will replace if the `ip'
   will become unresponsive. If `local' is TRUE then the `backup_server' is
   in the local cell, if FALSE it is in some other cell. */

void silc_server_backup_add(SilcServer server, SilcServerEntry backup_server,
			    const char *ip, int port, bool local)
{
  int i;

  if (!ip)
    return;

  if (!server->backup) {
    server->backup = silc_calloc(1, sizeof(*server->backup));
    if (!server->backup)
      return;
  }

  SILC_LOG_DEBUG(("Backup router %s will replace %s",
		  ((SilcSocketConnection)backup_server->connection)->ip,
		  ip, port));

  for (i = 0; i < server->backup->servers_count; i++) {
    if (!server->backup->servers[i].server) {
      server->backup->servers[i].server = backup_server;
      server->backup->servers[i].local = local;
      server->backup->servers[i].port = htons(port);
      memset(server->backup->servers[i].ip.data, 0,
	     sizeof(server->backup->servers[i].ip.data));
      silc_net_addr2bin(ip, server->backup->servers[i].ip.data,
			sizeof(server->backup->servers[i].ip.data));
      return;
    }
  }

  i = server->backup->servers_count;
  server->backup->servers = silc_realloc(server->backup->servers,
					 sizeof(*server->backup->servers) *
					 (i + 1));
  server->backup->servers[i].server = backup_server;
  server->backup->servers[i].local = local;
  server->backup->servers[i].port = htons(port);
  memset(server->backup->servers[i].ip.data, 0,
	 sizeof(server->backup->servers[i].ip.data));
  silc_net_addr2bin(ip, server->backup->servers[i].ip.data,
		    sizeof(server->backup->servers[i].ip.data));
  server->backup->servers_count++;
}

/* Returns backup router for IP and port in `replacing' or NULL if there
   does not exist backup router. */

SilcServerEntry silc_server_backup_get(SilcServer server, 
				       SilcServerID *server_id)
{
  int i;

  if (!server->backup)
    return NULL;

  for (i = 0; i < server->backup->servers_count; i++) {
    if (server->backup->servers[i].server &&
	server->backup->servers[i].port == server_id->port &&
	!memcmp(server->backup->servers[i].ip.data, server_id->ip.data,
		sizeof(server_id->ip.data))) {
      SILC_LOG_DEBUG(("Found backup router %s for %s",
		      server->backup->servers[i].server->server_name,
		      silc_id_render(server_id, SILC_ID_SERVER)));
      return server->backup->servers[i].server;
    }
  }

  return NULL;
}

/* Deletes the backup server `server_entry'. */

void silc_server_backup_del(SilcServer server, SilcServerEntry server_entry)
{
  int i;

  if (!server->backup)
    return;

  for (i = 0; i < server->backup->servers_count; i++) {
    if (server->backup->servers[i].server == server_entry) {
      SILC_LOG_DEBUG(("Removing %s as backup router",
		      silc_id_render(server->backup->servers[i].server->id,
				     SILC_ID_SERVER)));
      server->backup->servers[i].server = NULL;
      memset(server->backup->servers[i].ip.data, 0,
	     sizeof(server->backup->servers[i].ip.data));
    }
  }
}

/* Frees all data allocated for backup routers.  Call this after deleting
   all backup routers and when new routers are added no more, for example
   when shutting down the server. */

void silc_server_backup_free(SilcServer server)
{
  int i;

  if (!server->backup)
    return;

  /* Delete existing servers if caller didn't do it */
  for (i = 0; i < server->backup->servers_count; i++) {
    if (server->backup->servers[i].server)
      silc_server_backup_del(server, server->backup->servers[i].server);
  }

  silc_free(server->backup->servers);
  silc_free(server->backup);
  server->backup = NULL;
}

/* Marks the IP address and port from the `server_id' as  being replaced
   by backup router indicated by the `server'. If the router connects at
   a later time we can check whether it has been replaced by an backup
   router. */

void silc_server_backup_replaced_add(SilcServer server, 
				     SilcServerID *server_id,
				     SilcServerEntry server_entry)
{
  int i;
  SilcServerBackupReplaced *r = silc_calloc(1, sizeof(*r));;

  if (!server->backup)
    server->backup = silc_calloc(1, sizeof(*server->backup));
  if (!server->backup->replaced) {
    server->backup->replaced = 
      silc_calloc(1, sizeof(*server->backup->replaced));
    server->backup->replaced_count = 1;
  }

  SILC_LOG_DEBUG(("Replacing router %s with %s",
		  silc_id_render(server_id, SILC_ID_SERVER),
		  server_entry->server_name));

  memcpy(&r->ip, &server_id->ip, sizeof(server_id->ip));
  r->server = server_entry;

  for (i = 0; i < server->backup->replaced_count; i++) {
    if (!server->backup->replaced[i]) {
      server->backup->replaced[i] = r;
      return;
    }
  }

  i = server->backup->replaced_count;
  server->backup->replaced = silc_realloc(server->backup->replaced,
					  sizeof(*server->backup->replaced) *
					  (i + 1));
  server->backup->replaced[i] = r;
  server->backup->replaced_count++;
}

/* Checks whether the IP address and port from the `server_id' has been
   replaced by an backup router. If it has been then this returns TRUE
   and the bacup router entry to the `server' pointer if non-NULL. Returns
   FALSE if the router is not replaced by backup router. */

bool silc_server_backup_replaced_get(SilcServer server,
				     SilcServerID *server_id,
				     SilcServerEntry *server_entry)
{
  int i;

  if (!server->backup || !server->backup->replaced)
    return FALSE;

  for (i = 0; i < server->backup->replaced_count; i++) {
    if (!server->backup->replaced[i])
      continue;
    if (!memcmp(server->backup->replaced[i]->ip.data, server_id->ip.data,
		sizeof(server_id->ip.data))) {
      if (server_entry)
	*server_entry = server->backup->replaced[i]->server;
      SILC_LOG_DEBUG(("Router %s is replaced by %s",
		      silc_id_render(server_id, SILC_ID_SERVER),
		      server->backup->replaced[i]->server->server_name));
      return TRUE;
    }
  }

  SILC_LOG_DEBUG(("Router %s is not replaced by backup router",
		  silc_id_render(server_id, SILC_ID_SERVER)));
  return FALSE;
}

/* Deletes a replaced host by the set `server_entry. */

void silc_server_backup_replaced_del(SilcServer server,
				     SilcServerEntry server_entry)
{
  int i;

  if (!server->backup || !server->backup->replaced)
    return;

  for (i = 0; i < server->backup->replaced_count; i++) {
    if (!server->backup->replaced[i])
      continue;
    if (server->backup->replaced[i]->server == server_entry) {
      silc_free(server->backup->replaced[i]);
      server->backup->replaced[i] = NULL;
      return;
    }
  }
}

/* Broadcast the received packet indicated by `packet' to all of our backup 
   routers. All router wide information is passed using broadcast packets. 
   That is why all backup routers need to get this data too. It is expected
   that the caller already knows that the `packet' is broadcast packet. */

void silc_server_backup_broadcast(SilcServer server, 
				  SilcSocketConnection sender,
				  SilcPacketContext *packet)
{
  SilcServerEntry backup;
  SilcSocketConnection sock;
  SilcBuffer buffer;
  const SilcBufferStruct p;
  SilcIDListData idata;
  int i;

  if (!server->backup || server->server_type != SILC_ROUTER)
    return;

  SILC_LOG_DEBUG(("Broadcasting received packet to backup routers"));

  buffer = packet->buffer;
  silc_buffer_push(buffer, buffer->data - buffer->head);

  for (i = 0; i < server->backup->servers_count; i++) {
    backup = server->backup->servers[i].server;

    if (!backup || backup->connection == sender || 
	server->backup->servers[i].local == FALSE)
      continue;
    if (server->backup->servers[i].server == server->id_entry)
      continue;

    idata = (SilcIDListData)backup;
    sock = backup->connection;

    if (!silc_packet_send_prepare(sock, 0, 0, buffer->len, idata->hmac_send,
				  (const SilcBuffer)&p)) {
      SILC_LOG_ERROR(("Cannot send packet"));
      return;
    }
    silc_buffer_put((SilcBuffer)&p, buffer->data, buffer->len);
    silc_packet_encrypt(idata->send_key, idata->hmac_send, idata->psn_send++, 
			(SilcBuffer)&p, p.len);

    SILC_LOG_HEXDUMP(("Broadcasted packet, len %d", p.len), p.data, p.len);

    /* Now actually send the packet */
    silc_server_packet_send_real(server, sock, FALSE);

    /* Check for mandatory rekey */
    if (idata->psn_send == SILC_SERVER_REKEY_THRESHOLD)
      silc_schedule_task_add(server->schedule, sender->sock,
			     silc_server_rekey_callback, sender, 0, 1,
			     SILC_TASK_TIMEOUT, SILC_TASK_PRI_NORMAL);
  }
}

/* A generic routine to send data to all backup routers. If the `sender'
   is provided it will indicate the original sender of the packet and the
   packet won't be resent to that entity. The `data' is the data that will
   be assembled to packet context before sending. The packet will be
   encrypted this function. If the `force_send' is TRUE the data is sent
   immediately and not put to queue. If `local' is TRUE then the packet
   will be sent only to local backup routers inside the cell. If false the
   packet can go from one cell to the other. This function has no effect
   if there are no any backup routers. */

void silc_server_backup_send(SilcServer server,
			     SilcServerEntry sender,
			     SilcPacketType type,
			     SilcPacketFlags flags,
			     unsigned char *data,
			     SilcUInt32 data_len,
			     bool force_send,
			     bool local)
{
  SilcServerEntry backup;
  SilcSocketConnection sock;
  int i;

  if (!server->backup || server->server_type != SILC_ROUTER)
    return;

  for (i = 0; i < server->backup->servers_count; i++) {
    backup = server->backup->servers[i].server;
    if (!backup || sender == backup)
      continue;
    if (local && server->backup->servers[i].local == FALSE)
      continue;
    if (server->backup->servers[i].server == server->id_entry)
      continue;

    sock = backup->connection;

    SILC_LOG_DEBUG(("Sending %s packet to backup router %s (%s)",
		    silc_get_packet_name(type), sock->hostname, sock->ip));

    silc_server_packet_send(server, backup->connection, type, flags, 
			    data, data_len, force_send);
  }
}

/* Same as silc_server_backup_send but sets a specific Destination ID to
   the packet. The Destination ID is indicated by the `dst_id' and the
   ID type `dst_id_type'. For example, packets destined to channels must
   be sent using this function. */

void silc_server_backup_send_dest(SilcServer server,
				  SilcServerEntry sender,
				  SilcPacketType type,
				  SilcPacketFlags flags,
				  void *dst_id,
				  SilcIdType dst_id_type,
				  unsigned char *data,
				  SilcUInt32 data_len,
				  bool force_send,
				  bool local)
{
  SilcServerEntry backup;
  SilcSocketConnection sock;
  int i;

  if (!server->backup || server->server_type != SILC_ROUTER)
    return;

  for (i = 0; i < server->backup->servers_count; i++) {
    backup = server->backup->servers[i].server;
    if (!backup || sender == backup)
      continue;
    if (local && server->backup->servers[i].local == FALSE)
      continue;
    if (server->backup->servers[i].server == server->id_entry)
      continue;

    sock = backup->connection;

    SILC_LOG_DEBUG(("Sending %s packet to backup router %s (%s)",
		    silc_get_packet_name(type), sock->hostname, sock->ip));

    silc_server_packet_send_dest(server, backup->connection, type, flags, 
				 dst_id, dst_id_type, data, data_len, 
				 force_send);
  }
}

/* Processes incoming RESUME_ROUTER packet. This can give the packet
   for processing to the protocol handler or allocate new protocol if
   start command is received. */

void silc_server_backup_resume_router(SilcServer server, 
				      SilcSocketConnection sock, 
				      SilcPacketContext *packet)
{
  SilcUInt8 type, session;
  SilcServerBackupProtocolContext ctx;
  int i, ret;

  if (sock->type == SILC_SOCKET_TYPE_CLIENT ||
      sock->type == SILC_SOCKET_TYPE_UNKNOWN) {
    SILC_LOG_DEBUG(("Bad packet received"));
    return;
  }

  ret = silc_buffer_unformat(packet->buffer,
			     SILC_STR_UI_CHAR(&type),
			     SILC_STR_UI_CHAR(&session),
			     SILC_STR_END);
  if (ret < 0) {
    SILC_LOG_ERROR(("Malformed resume router packet received"));
    return;
  }
  
  /* Activate the protocol for this socket if necessary */
  if ((type == SILC_SERVER_BACKUP_RESUMED || 
      type == SILC_SERVER_BACKUP_RESUMED_GLOBAL) &&
      sock->type == SILC_SOCKET_TYPE_ROUTER && !sock->protocol && 
      ((SilcIDListData)sock->user_data)->status & 
      SILC_IDLIST_STATUS_DISABLED) {
    SilcServerEntry backup_router;

    if (silc_server_backup_replaced_get(server, 
					((SilcServerEntry)sock->
					 user_data)->id, 
					&backup_router)) {
      SilcSocketConnection bsock = 
	(SilcSocketConnection)backup_router->connection;
      if (bsock->protocol && bsock->protocol->protocol &&
	  bsock->protocol->protocol->type == SILC_PROTOCOL_SERVER_BACKUP) {
	sock->protocol = bsock->protocol;
	ctx = sock->protocol->context;
	ctx->sock = sock;
      }
    }
  }

  /* If the backup resuming protocol is active then process the packet
     in the protocol. */
  if (sock->protocol && sock->protocol->protocol &&
      sock->protocol->protocol->type == SILC_PROTOCOL_SERVER_BACKUP) {
    ctx = sock->protocol->context;
    ctx->type = type;

    if (type != SILC_SERVER_BACKUP_RESUMED &&
	type != SILC_SERVER_BACKUP_RESUMED_GLOBAL) {
      for (i = 0; i < ctx->sessions_count; i++) {
	if (session == ctx->sessions[i].session) {
	  ctx->session = session;
	  silc_protocol_execute(sock->protocol, server->schedule, 0, 0);
	  return;
	}
      }
    } else {
      silc_protocol_execute(sock->protocol, server->schedule, 0, 0);
      return;
    }

    SILC_LOG_ERROR(("Bad resume router packet RESUMED %d", type));
    return;
  }

  /* We don't have protocol active. If we are router and the packet is 
     coming from our primary router then lets check whether it means we've
     been replaced by an backup router in my cell. This is usually received
     immediately after we've connected to our primary router. */

  if (sock->type == SILC_SOCKET_TYPE_ROUTER &&
      sock && SILC_PRIMARY_ROUTE(server) == sock &&
      type == SILC_SERVER_BACKUP_REPLACED) {
    /* We have been replaced by an backup router in our cell. We must
       mark our primary router connection disabled since we are not allowed
       to use it at this moment. */
    SilcIDListData idata = (SilcIDListData)sock->user_data;
    SILC_LOG_INFO(("We are replaced by an backup router in this cell, will "
		   "wait until backup resuming protocol is executed"));
    idata->status |= SILC_IDLIST_STATUS_DISABLED;
    return;
  }

  if (type == SILC_SERVER_BACKUP_START ||
      type == SILC_SERVER_BACKUP_START_GLOBAL) {
    /* We have received a start for resuming protocol. */
    SilcServerBackupProtocolContext proto_ctx;

    proto_ctx = silc_calloc(1, sizeof(*proto_ctx));
    proto_ctx->server = server;
    proto_ctx->sock = sock;
    proto_ctx->responder = TRUE;
    proto_ctx->type = type;
    proto_ctx->session = session;
    proto_ctx->start = time(0);

    SILC_LOG_DEBUG(("Starting backup resuming protocol as responder"));
    SILC_LOG_INFO(("Starting backup resuming protocol"));

    /* Run the backup resuming protocol */
    silc_protocol_alloc(SILC_PROTOCOL_SERVER_BACKUP,
			&sock->protocol, proto_ctx, 
			silc_server_protocol_backup_done);
    silc_protocol_execute(sock->protocol, server->schedule, 0, 0);
  }
}

/* Timeout task callback to connect to remote router */

SILC_TASK_CALLBACK(silc_server_backup_connect_to_router)
{
  SilcServer server = app_context;
  SilcServerConnection sconn = (SilcServerConnection)context;
  int sock;
  const char *server_ip;

  SILC_LOG_DEBUG(("Connecting to router %s:%d", sconn->remote_host,
		  sconn->remote_port));

  /* Connect to remote host */
  server_ip = server->config->server_info->primary == NULL ? NULL :
    server->config->server_info->primary->server_ip;
  sock = silc_net_create_connection(server_ip, sconn->remote_port,
				    sconn->remote_host);
  if (sock < 0) {
    silc_schedule_task_add(server->schedule, 0,
			   silc_server_backup_connect_to_router,
			   context, 5, 0, SILC_TASK_TIMEOUT, 
			   SILC_TASK_PRI_NORMAL);
    return;
  }

  /* Continue with key exchange protocol */
  silc_server_start_key_exchange(server, sconn, sock);
}

/* Constantly tries to reconnect to a primary router indicated by the
   `ip' and `port'. The `connected' callback will be called when the
   connection is created. */

void silc_server_backup_reconnect(SilcServer server,
				  const char *ip, SilcUInt16 port,
				  SilcServerConnectRouterCallback callback,
				  void *context)
{
  SilcServerConnection sconn;

  SILC_LOG_INFO(("Attempting to reconnect to primary router"));

  sconn = silc_calloc(1, sizeof(*sconn));
  sconn->remote_host = strdup(ip);
  sconn->remote_port = port;
  sconn->callback = callback;
  sconn->callback_context = context;
  sconn->no_reconnect = TRUE;
  silc_schedule_task_add(server->schedule, 0, 
			 silc_server_backup_connect_to_router,
			 sconn, 1, 0, SILC_TASK_TIMEOUT,
			 SILC_TASK_PRI_NORMAL);
}

/* Task that is called after backup router has connected back to
   primary router and we are starting the resuming protocol */

SILC_TASK_CALLBACK(silc_server_backup_connected_later)
{
  SilcServerBackupProtocolContext proto_ctx = 
    (SilcServerBackupProtocolContext)context;
  SilcServer server = proto_ctx->server;
  SilcSocketConnection sock = proto_ctx->sock;

  SILC_LOG_DEBUG(("Starting backup resuming protocol as initiator"));
  SILC_LOG_INFO(("Starting backup resuming protocol"));

  /* Run the backup resuming protocol */
  silc_protocol_alloc(SILC_PROTOCOL_SERVER_BACKUP,
		      &sock->protocol, proto_ctx, 
		      silc_server_protocol_backup_done);
  silc_protocol_execute(sock->protocol, server->schedule, 0, 0);
}

/* Called when we've established connection back to our primary router
   when we've acting as backup router and have replaced the primary router
   in the cell. This function will start the backup resuming protocol. */

void silc_server_backup_connected(SilcServer server,
				  SilcServerEntry server_entry,
				  void *context)
{
  SilcServerBackupProtocolContext proto_ctx;
  SilcSocketConnection sock;

  if (!server_entry) {
    /* Try again */
    SilcServerConfigRouter *primary;
    primary = silc_server_config_get_primary_router(server);
    if (primary)
      silc_server_backup_reconnect(server,
				   primary->host, primary->port,
				   silc_server_backup_connected,
				   context);
    return;
  }

  sock = (SilcSocketConnection)server_entry->connection;
  proto_ctx = silc_calloc(1, sizeof(*proto_ctx));
  proto_ctx->server = server;
  proto_ctx->sock = sock;
  proto_ctx->responder = FALSE;
  proto_ctx->type = SILC_SERVER_BACKUP_START;
  proto_ctx->start = time(0);

  /* Start through scheduler */
  silc_schedule_task_add(server->schedule, 0,
			 silc_server_backup_connected_later,
			 proto_ctx, 0, 1,
			 SILC_TASK_TIMEOUT,
			 SILC_TASK_PRI_NORMAL);
}

/* Called when normal server has connected to its primary router after
   backup router has sent the START packet in reusming protocol. We will
   move the protocol context from the backup router connection to the
   primary router. */

static void silc_server_backup_connect_primary(SilcServer server,
					       SilcServerEntry server_entry,
					       void *context)
{
  SilcSocketConnection backup_router = (SilcSocketConnection)context;
  SilcServerBackupProtocolContext ctx;
  SilcSocketConnection sock;
  SilcIDListData idata;
  SilcBuffer buffer;

  if (!server_entry) {
    /* Try again */
    SilcServerConfigRouter *primary;
    primary = silc_server_config_get_primary_router(server);
    if (primary)
      silc_server_backup_reconnect(server,
				   primary->host, primary->port,
				   silc_server_backup_connect_primary,
				   context);
    return;
  }

  ctx = (SilcServerBackupProtocolContext)backup_router->protocol->context;
  sock = (SilcSocketConnection)server_entry->connection;
  idata = (SilcIDListData)server_entry;

  SILC_LOG_DEBUG(("Sending CONNECTED packet (session %d)", ctx->session));

  /* Send the CONNECTED packet back to the backup router. */
  buffer = silc_buffer_alloc(2);
  silc_buffer_pull_tail(buffer, SILC_BUFFER_END(buffer));
  silc_buffer_format(buffer,
		     SILC_STR_UI_CHAR(SILC_SERVER_BACKUP_CONNECTED),
		     SILC_STR_UI_CHAR(ctx->session),
		     SILC_STR_END);
  silc_server_packet_send(server, backup_router, 
			  SILC_PACKET_RESUME_ROUTER, 0, 
			  buffer->data, buffer->len, FALSE);
  silc_buffer_free(buffer);

  /* The primary connection is disabled until it sends the RESUMED packet
     to us. */
  idata->status |= SILC_IDLIST_STATUS_DISABLED;

  /* Move this protocol context from this backup router connection to
     the primary router connection since it will send the subsequent
     packets in this protocol. We don't talk with backup router 
     anymore. */
  sock->protocol = backup_router->protocol;
  ctx->sock = (SilcSocketConnection)server_entry->connection;
  backup_router->protocol = NULL;
}

SILC_TASK_CALLBACK(silc_server_backup_send_resumed)
{
  SilcProtocol protocol = (SilcProtocol)context;
  SilcServerBackupProtocolContext ctx = protocol->context;
  SilcServer server = ctx->server;
  SilcBuffer packet;
  int i;

  for (i = 0; i < ctx->sessions_count; i++)
    if (ctx->sessions[i].server_entry == ctx->sock->user_data)
      ctx->session = ctx->sessions[i].session;
  
  /* We've received all the CONNECTED packets and now we'll send the
     ENDING packet to the new primary router. */
  packet = silc_buffer_alloc(2);
  silc_buffer_pull_tail(packet, SILC_BUFFER_END(packet));
  silc_buffer_format(packet,
		     SILC_STR_UI_CHAR(SILC_SERVER_BACKUP_ENDING),
		     SILC_STR_UI_CHAR(ctx->session),
		     SILC_STR_END);
  silc_server_packet_send(server, ctx->sock, 
			  SILC_PACKET_RESUME_ROUTER, 0, 
			  packet->data, packet->len, FALSE);
  silc_buffer_free(packet);
  
  protocol->state = SILC_PROTOCOL_STATE_END;
}

/* Backup resuming protocol. This protocol is executed when the primary
   router wants to resume its position as being primary router. */

SILC_TASK_CALLBACK_GLOBAL(silc_server_protocol_backup)
{
  SilcProtocol protocol = (SilcProtocol)context;
  SilcServerBackupProtocolContext ctx = protocol->context;
  SilcServer server = ctx->server;
  SilcBuffer packet;
  SilcIDCacheList list;
  SilcIDCacheEntry id_cache;
  SilcServerEntry server_entry;
  int i;

  if (protocol->state == SILC_PROTOCOL_STATE_UNKNOWN)
    protocol->state = SILC_PROTOCOL_STATE_START;

  switch(protocol->state) {
  case SILC_PROTOCOL_STATE_START:
    if (ctx->responder == FALSE) {
      /* Initiator of the protocol. We are backup router */

      packet = silc_buffer_alloc(2);
      silc_buffer_pull_tail(packet, SILC_BUFFER_END(packet));

      /* Send the START packet to primary router and normal servers. */
      if (silc_idcache_get_all(server->local_list->servers, &list)) {
	if (silc_idcache_list_first(list, &id_cache)) {
	  while (id_cache) {
	    server_entry = (SilcServerEntry)id_cache->context;
	    if (!server_entry || (server_entry == server->id_entry) || 
		!server_entry->connection || !server_entry->data.send_key ||
		(server_entry->data.status & SILC_IDLIST_STATUS_DISABLED)) {
	      if (!silc_idcache_list_next(list, &id_cache))
		break;
	      else
		continue;
	    }

	    ctx->sessions = silc_realloc(ctx->sessions,
					 sizeof(*ctx->sessions) *
					 (ctx->sessions_count + 1));
	    ctx->sessions[ctx->sessions_count].session = ctx->sessions_count;
	    ctx->sessions[ctx->sessions_count].connected = FALSE;
	    ctx->sessions[ctx->sessions_count].server_entry = server_entry;

	    SILC_LOG_DEBUG(("Sending START to %s (session %d)", 
			    server_entry->server_name, ctx->sessions_count));

	    /* This connection is performing this protocol too now */
	    ((SilcSocketConnection)server_entry->connection)->protocol =
	      protocol;

	    if (server_entry->server_type == SILC_ROUTER)
	      packet->data[0] = SILC_SERVER_BACKUP_START;
	    else
	      packet->data[0] = SILC_SERVER_BACKUP_START_GLOBAL;
	    packet->data[1] = ctx->sessions_count;
	    silc_server_packet_send(server, server_entry->connection,
				    SILC_PACKET_RESUME_ROUTER, 0, 
				    packet->data, packet->len, FALSE);
	    ctx->sessions_count++;

	    if (!silc_idcache_list_next(list, &id_cache))
	      break;
	  }
	}

	silc_idcache_list_free(list);
      }

      if (silc_idcache_get_all(server->global_list->servers, &list)) {
	if (silc_idcache_list_first(list, &id_cache)) {
	  while (id_cache) {
	    server_entry = (SilcServerEntry)id_cache->context;
	    if (!server_entry || (server_entry == server->id_entry) || 
		!server_entry->connection || !server_entry->data.send_key ||
		(server_entry->data.status & SILC_IDLIST_STATUS_DISABLED)) {
	      if (!silc_idcache_list_next(list, &id_cache))
		break;
	      else
		continue;
	    }

	    ctx->sessions = silc_realloc(ctx->sessions,
					 sizeof(*ctx->sessions) *
					 (ctx->sessions_count + 1));
	    ctx->sessions[ctx->sessions_count].session = ctx->sessions_count;
	    ctx->sessions[ctx->sessions_count].connected = FALSE;
	    ctx->sessions[ctx->sessions_count].server_entry = server_entry;

	    SILC_LOG_DEBUG(("Sending START to %s (session %d)", 
			    server_entry->server_name, ctx->sessions_count));

	    /* This connection is performing this protocol too now */
	    ((SilcSocketConnection)server_entry->connection)->protocol =
	      protocol;

	    if (server_entry->server_type == SILC_ROUTER)
	      packet->data[0] = SILC_SERVER_BACKUP_START;
	    else
	      packet->data[0] = SILC_SERVER_BACKUP_START_GLOBAL;
	    packet->data[1] = ctx->sessions_count;
	    silc_server_packet_send(server, server_entry->connection,
				    SILC_PACKET_RESUME_ROUTER, 0, 
				    packet->data, packet->len, FALSE);
	    ctx->sessions_count++;

	    if (!silc_idcache_list_next(list, &id_cache))
	      break;
	  }
	}

	silc_idcache_list_free(list);
      }

      silc_buffer_free(packet);

      /* If we are not standalone and our primary is not the one we've
	 talking to now, then announce our information to it since we
	 haven't done that yet.  Standalone backup router announces
	 these during connecting to the primary. */
      if (!server->standalone && SILC_PRIMARY_ROUTE(server) != ctx->sock) {
	silc_server_announce_servers(server, TRUE, 0, ctx->sock);
	silc_server_announce_clients(server, 0, ctx->sock);
	silc_server_announce_channels(server, 0, ctx->sock);
      }

      protocol->state++;
    } else {
      /* Responder of the protocol. */
      SilcServerConfigRouter *primary;

      /* We should have received START or START_GLOBAL packet */
      if (ctx->type != SILC_SERVER_BACKUP_START &&
	  ctx->type != SILC_SERVER_BACKUP_START_GLOBAL) {
	SILC_LOG_ERROR(("Bad resume router packet START %d", ctx->type));
	break;
      }

      /* Connect to the primary router that was down that is now supposed
	 to be back online. We send the CONNECTED packet after we've
	 established the connection to the primary router. */
      primary = silc_server_config_get_primary_router(server);
      if (primary && server->backup_primary) {
	SILC_LOG_DEBUG(("Received START (session %d), reconnect to router",
			ctx->session));
	silc_server_backup_reconnect(server,
				     primary->host, primary->port,
				     silc_server_backup_connect_primary,
				     ctx->sock);
      } else {
	/* Nowhere to connect just return the CONNECTED packet */
	SILC_LOG_DEBUG(("Received START (session %d), send CONNECTED back",
			ctx->session));

	/* Send the CONNECTED packet back to the backup router. */
	packet = silc_buffer_alloc(2);
	silc_buffer_pull_tail(packet, SILC_BUFFER_END(packet));
	silc_buffer_format(packet,
			   SILC_STR_UI_CHAR(SILC_SERVER_BACKUP_CONNECTED),
			   SILC_STR_UI_CHAR(ctx->session),
			   SILC_STR_END);
	silc_server_packet_send(server, ctx->sock, 
				SILC_PACKET_RESUME_ROUTER, 0, 
				packet->data, packet->len, FALSE);
	silc_buffer_free(packet);
      }

      if (server->server_type == SILC_ROUTER &&
	  (!server->router || 
	   server->router->data.status & SILC_IDLIST_STATUS_DISABLED))
	protocol->state++;
      else
	protocol->state = SILC_PROTOCOL_STATE_END;

      ctx->sessions = silc_realloc(ctx->sessions,
				   sizeof(*ctx->sessions) *
				   (ctx->sessions_count + 1));
      ctx->sessions[ctx->sessions_count].session = ctx->session;
      ctx->sessions_count++;
    }
    break;

  case 2:
    if (ctx->responder == FALSE) {
      /* Initiator */

      /* We should have received CONNECTED packet */
      if (ctx->type != SILC_SERVER_BACKUP_CONNECTED) {
	SILC_LOG_ERROR(("Bad resume router packet CONNECTED %d", ctx->type));
	break;
      }

      SILC_LOG_DEBUG(("Received CONNECTED (session %d)", ctx->session));

      for (i = 0; i < ctx->sessions_count; i++) {
	if (ctx->sessions[i].session == ctx->session) {
	  ctx->sessions[i].connected = TRUE;
	  break;
	}
      }

      for (i = 0; i < ctx->sessions_count; i++) {
	if (!ctx->sessions[i].connected)
	  return;
      }

      SILC_LOG_DEBUG(("All sessions has returned CONNECTED packets"));
      SILC_LOG_DEBUG(("Sending ENDING packet to primary router"));

      /* Send with a timeout */
      silc_schedule_task_add(server->schedule, 0, 
			     silc_server_backup_send_resumed,
			     protocol, 1, 0, SILC_TASK_TIMEOUT,
			     SILC_TASK_PRI_NORMAL);
      return;
    } else {
      /* Responder */

      /* We should have been received ENDING packet */
      if (ctx->type != SILC_SERVER_BACKUP_ENDING) {
	SILC_LOG_ERROR(("Bad resume router packet ENDING %d", ctx->type));
	break;
      }

      SILC_LOG_DEBUG(("Received ENDING packet, we are going to resume now"));

      /* This state is received by the primary router but also servers
	 and perhaps other routers so check that if we are the primary
	 router of the cell then start sending RESUMED packets.  If we
	 are normal server or one of those other routers then procede
	 to next state. */
      if (server->router &&
	  !(server->router->data.status & SILC_IDLIST_STATUS_DISABLED) &&
	  silc_server_config_is_primary_route(server)) {
	/* We'll wait for RESUMED packet */
	protocol->state = SILC_PROTOCOL_STATE_END;
	break;
      }

      /* Switch announced informations to our primary router of using the
	 backup router. */
      silc_server_local_servers_toggle_enabled(server, TRUE);
      silc_server_update_servers_by_server(server, ctx->sock->user_data, 
					   server->router);
      silc_server_update_clients_by_server(server, ctx->sock->user_data,
					   server->router, TRUE);
      if (server->server_type == SILC_SERVER)
	silc_server_update_channels_by_server(server, ctx->sock->user_data, 
					      server->router);

      packet = silc_buffer_alloc(2);
      silc_buffer_pull_tail(packet, SILC_BUFFER_END(packet));

      /* We are the primary router, start sending RESUMED packets. */
      if (silc_idcache_get_all(server->local_list->servers, &list)) {
	if (silc_idcache_list_first(list, &id_cache)) {
	  while (id_cache) {
	    server_entry = (SilcServerEntry)id_cache->context;
	    if (!server_entry || (server_entry == server->id_entry) || 
		!server_entry->connection || !server_entry->data.send_key) {
	      if (!silc_idcache_list_next(list, &id_cache))
		break;
	      else
		continue;
	    }

	    SILC_LOG_DEBUG(("Sending RESUMED to %s",
			    server_entry->server_name));

	    server_entry->data.status &= ~SILC_IDLIST_STATUS_DISABLED;

	    /* This connection is performing this protocol too now */
	    ((SilcSocketConnection)server_entry->connection)->protocol =
	      protocol;

	    if (server_entry->server_type == SILC_ROUTER)
	      packet->data[0] = SILC_SERVER_BACKUP_RESUMED;
	    else
	      packet->data[0] = SILC_SERVER_BACKUP_RESUMED_GLOBAL;
	    silc_server_packet_send(server, server_entry->connection,
				    SILC_PACKET_RESUME_ROUTER, 0, 
				    packet->data, packet->len, FALSE);

	    if (!silc_idcache_list_next(list, &id_cache))
	      break;
	  }
	}

	silc_idcache_list_free(list);
      }

      if (silc_idcache_get_all(server->global_list->servers, &list)) {
	if (silc_idcache_list_first(list, &id_cache)) {
	  while (id_cache) {
	    server_entry = (SilcServerEntry)id_cache->context;
	    if (!server_entry || (server_entry == server->id_entry) || 
		!server_entry->connection || !server_entry->data.send_key) {
	      if (!silc_idcache_list_next(list, &id_cache))
		break;
	      else
		continue;
	    }

	    SILC_LOG_DEBUG(("Sending RESUMED to %s",
			    server_entry->server_name));

	    server_entry->data.status &= ~SILC_IDLIST_STATUS_DISABLED;

	    /* This connection is performing this protocol too now */
	    ((SilcSocketConnection)server_entry->connection)->protocol =
	      protocol;

	    if (server_entry->server_type == SILC_ROUTER)
	      packet->data[0] = SILC_SERVER_BACKUP_RESUMED;
	    else
	      packet->data[0] = SILC_SERVER_BACKUP_RESUMED_GLOBAL;
	    silc_server_packet_send(server, server_entry->connection,
				    SILC_PACKET_RESUME_ROUTER, 0, 
				    packet->data, packet->len, FALSE);

	    if (!silc_idcache_list_next(list, &id_cache))
	      break;
	  }
	}

	silc_idcache_list_free(list);
      }

      silc_buffer_free(packet);

      SILC_LOG_INFO(("We are now the primary router of our cell again"));
      server->wait_backup = FALSE;

      /* For us this is the end of this protocol. */
      if (protocol->final_callback)
	silc_protocol_execute_final(protocol, server->schedule);
      else
	silc_protocol_free(protocol);
    }
    break;

  case SILC_PROTOCOL_STATE_END:
    {
      SilcServerEntry router, backup_router;

      /* We should have been received RESUMED packet from our primary
	 router. */
      if (ctx->type != SILC_SERVER_BACKUP_RESUMED &&
	  ctx->type != SILC_SERVER_BACKUP_RESUMED_GLOBAL) {
	SILC_LOG_ERROR(("Bad resume router packet RESUMED %d", ctx->type));
	break;
      }

      SILC_LOG_DEBUG(("Received RESUMED from new primary router"));

      if (server->backup_router)
	server->server_type = SILC_BACKUP_ROUTER;

      /* We have now new primary router. All traffic goes there from now on. */
      router = (SilcServerEntry)ctx->sock->user_data;
      if (silc_server_backup_replaced_get(server, router->id, 
					  &backup_router)) {

	if (backup_router == server->router) {
	  /* We have new primary router now */
	  server->id_entry->router = router;
	  server->router = router;
	  SILC_LOG_INFO(("Switching back to primary router %s",
			 server->router->server_name));
	} else {
	  /* We are connected to new primary and now continue using it */
	  SILC_LOG_INFO(("Resuming the use of primary router %s",
			 router->server_name));
	}

	/* Update the client entries of the backup router to the new 
	   router */
	silc_server_local_servers_toggle_enabled(server, FALSE);
	router->data.status &= ~SILC_IDLIST_STATUS_DISABLED;
	silc_server_update_servers_by_server(server, backup_router, router);
	silc_server_update_clients_by_server(server, NULL, router, FALSE);
	if (server->server_type == SILC_SERVER)
	  silc_server_update_channels_by_server(server, backup_router, router);
 	silc_server_backup_replaced_del(server, backup_router);

	/* Announce all of our information to the router. */
	if (server->server_type == SILC_ROUTER)
	  silc_server_announce_servers(server, FALSE, ctx->start,
				       router->connection);

	/* Announce our clients and channels to the router */
	silc_server_announce_clients(server, ctx->start,
				     router->connection);
	silc_server_announce_channels(server, ctx->start,
				      router->connection);
      }

      /* Send notify about primary router going down to local operators */
      SILC_SERVER_SEND_OPERS(server, FALSE, TRUE,
			     SILC_NOTIFY_TYPE_NONE,
			     ("%s resumed the use of primary router %s",
			      server->server_name,
			      server->router->server_name));

      /* Protocol has ended, call the final callback */
      if (protocol->final_callback)
	silc_protocol_execute_final(protocol, server->schedule);
      else
	silc_protocol_free(protocol);
    }
    break;

  case SILC_PROTOCOL_STATE_ERROR:
    /* Protocol has ended, call the final callback */
    if (protocol->final_callback)
      silc_protocol_execute_final(protocol, server->schedule);
    else
      silc_protocol_free(protocol);
    break;

  case SILC_PROTOCOL_STATE_FAILURE:
    /* Protocol has ended, call the final callback */
    SILC_LOG_ERROR(("Error during backup resume: received Failure"));
    if (protocol->final_callback)
      silc_protocol_execute_final(protocol, server->schedule);
    else
      silc_protocol_free(protocol);
    break;

  case SILC_PROTOCOL_STATE_UNKNOWN:
    break;
  }
}

SILC_TASK_CALLBACK(silc_server_protocol_backup_done)
{
  SilcProtocol protocol = (SilcProtocol)context;
  SilcServerBackupProtocolContext ctx = protocol->context;
  SilcServer server = ctx->server;
  SilcServerEntry server_entry;
  SilcSocketConnection sock;
  SilcIDCacheList list;
  SilcIDCacheEntry id_cache;

  if (protocol->state == SILC_PROTOCOL_STATE_ERROR ||
      protocol->state == SILC_PROTOCOL_STATE_FAILURE) {
    SILC_LOG_ERROR(("Error occurred during backup router resuming protcool"));
  }

  /* Remove this protocol from all server entries that has it */
  if (silc_idcache_get_all(server->local_list->servers, &list)) {
    if (silc_idcache_list_first(list, &id_cache)) {
      while (id_cache) {
	server_entry = (SilcServerEntry)id_cache->context;
	sock = (SilcSocketConnection)server_entry->connection;

	if (sock->protocol == protocol) {
	  sock->protocol = NULL;

	  if (server_entry->data.status & SILC_IDLIST_STATUS_DISABLED)
	    server_entry->data.status &= ~SILC_IDLIST_STATUS_DISABLED;
	}
	
	if (!silc_idcache_list_next(list, &id_cache))
	  break;
      }
    }
    silc_idcache_list_free(list);
  }

  if (silc_idcache_get_all(server->global_list->servers, &list)) {
    if (silc_idcache_list_first(list, &id_cache)) {
      while (id_cache) {
	server_entry = (SilcServerEntry)id_cache->context;
	sock = (SilcSocketConnection)server_entry->connection;

	if (sock->protocol == protocol) {
	  sock->protocol = NULL;

	  if (server_entry->data.status & SILC_IDLIST_STATUS_DISABLED)
	    server_entry->data.status &= ~SILC_IDLIST_STATUS_DISABLED;
	}
	
	if (!silc_idcache_list_next(list, &id_cache))
	  break;
      }
    }
    silc_idcache_list_free(list);
  }

  SILC_LOG_DEBUG(("Backup resuming protocol has ended"));

  if (ctx->sock->protocol)
    ctx->sock->protocol = NULL;
  silc_protocol_free(protocol);
  silc_free(ctx->sessions);
  silc_free(ctx);
}