/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
 It is considered beerware. Prost. Skol. Cheers or whatever. */

#ifndef OT_LIVESYNC_H__
#define OT_LIVESYNC_H__

#include "trackerlogic.h"

/*
  Syncing is done as udp packets in the multicast group 224.0.23.5, on the
  port livesync.cluster.listen names, 9696 by default

  Each tracker should join the multicast group and send its live sync packets
  to that group, using a ttl of 1

  Format of all sync packets is straight forward, packet type determines
  which kind of packet this is:

    0x0000 0x04 id of tracker instance
    0x0004 0x04 packet type

                             ########
 ######## PEER SYNC PROTOCOL ########
 ########

  Each tracker instance accumulates announce requests until its buffer is
  full or a timeout is reached. Then it broadcasts its live sync packer:

  packet type SYNC_LIVE4
  [ 0x0008 0x14 info_hash
    0x001c 0x04 peer's ipv4 address
    0x0020 0x02 peer's port
    0x0024 0x02 peer flags v1 ( SEEDING = 0x80, COMPLETE = 0x40, STOPPED = 0x20 )
  ]*

  packet type SYNC_LIVE6
  [ 0x0008 0x14 info_hash
    0x001c 0x10 peer's ipv6 address
    0x002c 0x02 peer's port
    0x002e 0x02 peer flags v1 ( SEEDING = 0x80, COMPLETE = 0x40, STOPPED = 0x20 )
  ]*
*/

#ifdef WANT_SYNC_LIVE

#define LIVESYNC_PORT 9696

void livesync_init(void);
void livesync_deinit(void);

/* The group to join and to send to, (defaults to 224.0.23.5).
   Returns -1 if group is not a v4 multicast address. */
int  livesync_set_group(const ot_ip6 group);

/* Join multicast group for listening and create sending socket */
void livesync_bind_mcast(ot_ip6 ip, uint16_t port);

/* Inform live sync about whats going on. */
void livesync_tell(struct ot_workstruct *ws);

/* Tickle the live sync module from time to time, so no events get
   stuck when there's not enough traffic to fill udp packets fast
   enough */
void livesync_ticker(void);

/* Handle an incoming live sync packet */
void handle_livesync(const int64_t sock);

#else

/* If no syncing is required, save calling code from #ifdef
   constructions */
#define livesync_deinit()
#define livesync_init()
#define livesync_ticker()
#define handle_livesync(a)

#endif

#endif