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112 lines
3.3 KiB
112 lines
3.3 KiB
/* This software was written by Dirk Engling <erdgeist@erdgeist.org> |
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It is considered beerware. Prost. Skol. Cheers or whatever. |
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$id$ */ |
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#ifndef __OT_LIVESYNC_H__ |
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#define __OT_LIVESYNC_H__ |
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#include "io.h" |
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#include "trackerlogic.h" |
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/* |
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Syncing is done as udp packets in the multicast domain 224.0.42.5 port 9696 |
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Each tracker should join the multicast group and send its live sync packets |
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to that group, using a ttl of 1 |
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Format of all sync packets is straight forward, packet type determines |
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which kind of packet this is: |
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0x0000 0x04 id of tracker instance |
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0x0004 0x04 packet type |
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######## |
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######## PEER SYNC PROTOCOL ######## |
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######## |
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Each tracker instance accumulates announce requests until its buffer is |
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full or a timeout is reached. Then it broadcasts its live sync packer: |
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packet type SYNC_LIVE |
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[ 0x0008 0x14 info_hash |
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0x001c 0x04 peer's ipv4 address |
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0x0020 0x02 peer's port |
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0x0024 0x02 peer flags v1 ( SEEDING = 0x80, COMPLETE = 0x40, STOPPED = 0x20 ) |
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]* |
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######## |
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######## SCRAPE SYNC PROTOCOL ######## |
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######## |
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Each tracker instance SHOULD broadcast a beacon once in every 5 minutes after |
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running at least 30 minutes: |
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packet type SYNC_SCRAPE_BEACON |
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[ 0x0008 0x08 amount of torrents served |
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] |
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If a tracker instance receives a beacon from another instance that has more than |
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twice its torrent count, it asks for a scrape. It must wait for at least 5 + 1 |
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minutes in order to inspect beacons from all tracker instances and chose the one |
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with most torrents. |
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If it sees a SYNC_SCRAPE_TELL within that time frame, it's likely, that another |
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scrape sync is going on. So one tracker instance MUST NOT react to beacons within |
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5 minutes of last seeing a SYNC_SCRAPE_TELL packet. After a scrape sync all |
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tracker instances have updated their torrents, so an instance in a "want inquire" |
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state should wait for the next round of beacons to chose the tracker with most |
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data again. |
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packet type SYNC_SCRAPE_INQUIRE |
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[ 0x0008 0x04 id of tracker instance to inquire |
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] |
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The inquired tracker instance answers with as many scrape tell packets it needs |
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to deliver stats about all its torrents |
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packet type SYNC_SCRAPE_TELL |
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[ 0x0008 0x14 info_hash |
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0x001c 0x04 base offset (i.e. when was it last announced, in minutes) |
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0x0020 0x08 downloaded count |
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]* |
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Each tracker instance that receives a scrape tell, looks up each torrent and |
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compares downloaded count with its own counter. It can send out its own scrape |
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tell packets, if it knows more. |
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*/ |
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#ifdef WANT_SYNC_LIVE |
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#define LIVESYNC_PORT 9696 |
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void livesync_init(); |
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void livesync_deinit(); |
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/* Join multicast group for listening and create sending socket */ |
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void livesync_bind_mcast( char *ip, uint16_t port ); |
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/* Inform live sync about whats going on. */ |
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void livesync_tell( ot_hash * const info_hash, const ot_peer * const peer ); |
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/* Tickle the live sync module from time to time, so no events get |
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stuck when there's not enough traffic to fill udp packets fast |
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enough */ |
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void livesync_ticker( ); |
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/* Handle an incoming live sync packet */ |
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void handle_livesync( const int64 serversocket ); |
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#else |
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/* If no syncing is required, save calling code from #ifdef |
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constructions */ |
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#define livesync_deinit() |
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#define livesync_init() |
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#define livesync_ticker() |
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#define handle_livesync(a) |
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#endif |
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#endif
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