/*
  *  OpenVPN -- An application to securely tunnel IP networks
  *             over a single UDP port, with support for SSL/TLS-based
  *             session authentication and key exchange,
  *             packet encryption, packet authentication, and
  *             packet compression.
  *

  *  Copyright (C) 2002-2008 Telethra, Inc. <sales@openvpn.net>

  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2
  *  as published by the Free Software Foundation.
  *
  *  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.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program (see the file COPYING included with this
  *  distribution); if not, write to the Free Software Foundation, Inc.,
  *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
 /*
  * This routines implement a reliability layer on top of UDP,
  * so that TLS can be run over UDP.
  */
 
 #if defined(USE_CRYPTO) && defined(USE_SSL)
 
 #ifndef RELIABLE_H
 #define RELIABLE_H
 
 #include "basic.h"
 #include "buffer.h"
 #include "packet_id.h"
 #include "session_id.h"
 #include "mtu.h"
 
 /* #define EXPONENTIAL_BACKOFF */
 
 #define RELIABLE_ACK_SIZE 8
 
 struct reliable_ack
 {
   int len;
   packet_id_type packet_id[RELIABLE_ACK_SIZE];
 };
 
 /* no active buffers? */
 static inline bool
 reliable_ack_empty (struct reliable_ack *ack)
 {
   return !ack->len;
 }
 
 /* get a packet_id from buf */
 bool reliable_ack_read_packet_id (struct buffer *buf, packet_id_type *pid);
 
 /* acknowledge a packet_id by adding it to a struct reliable_ack */
 bool reliable_ack_acknowledge_packet_id (struct reliable_ack *ack, packet_id_type pid);
 
 /* read a packet ID acknowledgement record from buf */
 bool reliable_ack_read (struct reliable_ack *ack,
 			struct buffer *buf, const struct session_id *sid);
 
 /* write a packet ID acknowledgement record to buf */
 bool reliable_ack_write (struct reliable_ack *ack,
 			 struct buffer *buf,
 			 const struct session_id *sid, int max, bool prepend);
 
 /* print a reliable ACK record coming off the wire */
 const char *reliable_ack_print (struct buffer *buf, bool verbose, struct gc_arena *gc);
 
 /* add to extra_frame the maximum number of bytes we will need for reliable_ack_write */
 void reliable_ack_adjust_frame_parameters (struct frame* frame, int max);
 
 void reliable_ack_debug_print (const struct reliable_ack *ack, char *desc);
 
 #define RELIABLE_CAPACITY 8
 
 struct reliable_entry
 {
   bool active;
   interval_t timeout;
   time_t next_try;
   packet_id_type packet_id;
   int opcode;
   struct buffer buf;
 };
 
 struct reliable
 {
   int size;
   interval_t initial_timeout;
   packet_id_type packet_id;
   int offset;

   bool hold; /* don't xmit until reliable_schedule_now is called */

   struct reliable_entry array[RELIABLE_CAPACITY];
 };
 
 void reliable_debug_print (const struct reliable *rel, char *desc);
 
 /* set sending timeout (after this time we send again until ACK) */
 static inline void
 reliable_set_timeout (struct reliable *rel, interval_t timeout)
 {
   rel->initial_timeout = timeout;
 }
 

 void reliable_init (struct reliable *rel, int buf_size, int offset, int array_size, bool hold);

 
 void reliable_free (struct reliable *rel);
 
 /* no active buffers? */
 bool reliable_empty (const struct reliable *rel);
 
 /* in how many seconds should we wake up to check for timeout */
 interval_t reliable_send_timeout (const struct reliable *rel);
 
 /* del acknowledged items from send buf */
 void reliable_send_purge (struct reliable *rel, struct reliable_ack *ack);
 
 /* true if at least one free buffer available */
 bool reliable_can_get (const struct reliable *rel);
 
 /* make sure that incoming packet ID isn't a replay */
 bool reliable_not_replay (const struct reliable *rel, packet_id_type id);
 
 /* make sure that incoming packet ID won't deadlock the receive buffer */
 bool reliable_wont_break_sequentiality (const struct reliable *rel, packet_id_type id);
 
 /* grab a free buffer */
 struct buffer *reliable_get_buf (struct reliable *rel);
 
 /* grab a free buffer, fail if buffer clogged by unacknowledged low packet IDs */
 struct buffer *reliable_get_buf_output_sequenced (struct reliable *rel);
 
 /* get active buffer for next sequentially increasing key ID */
 struct buffer *reliable_get_buf_sequenced (struct reliable *rel);
 
 /* return true if reliable_send would return a non-NULL result */
 bool reliable_can_send (const struct reliable *rel);
 
 /* return next buffer to send to remote */
 struct buffer *reliable_send (struct reliable *rel, int *opcode);
 
 /* schedule all pending packets for immediate retransmit */
 void reliable_schedule_now (struct reliable *rel);
 
 /* enable an incoming buffer previously returned by a get function as active */
 void reliable_mark_active_incoming (struct reliable *rel, struct buffer *buf,
 				    packet_id_type pid, int opcode);
 
 /* enable an outgoing buffer previously returned by a get function as active. */
 void reliable_mark_active_outgoing (struct reliable *rel, struct buffer *buf, int opcode);
 
 /* delete a buffer previously activated by reliable_mark_active() */
 void reliable_mark_deleted (struct reliable *rel, struct buffer *buf, bool inc_pid);
 
 #endif /* RELIABLE_H */
 #endif /* USE_CRYPTO && USE_SSL */