1 files changed, 80 insertions, 0 deletions

diff --git a/src/ot_livesync.h b/src/ot_livesync.h
new file mode 100644
index 0000000..cf3c64c
--- /dev/null
+++ b/src/ot_livesync.h
@@ -0,0 +1,80 @@
+/* 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