From 2df09905f5540fee096d48a92cb0c42558498a12 Mon Sep 17 00:00:00 2001
From: erdgeist <>
Date: Fri, 2 Jan 2009 08:57:53 +0000
Subject: [PATCH] * opentracker now drops permissions in correct order and
 really chroots() if ran as root * lock passing between add_peer_to_torrent
 and return_peers_for_torrent is now avoided by providing a more general
 add_peer_to_torrent_and_return_peers function that can be used with NULL
 parameters to not return any peers (in sync case) * in order to keep a fast
 overview how many torrents opentracker maintains, every mutex_bucket_unlock
 operation expects an additional integer parameter that tells ot_mutex.c how
 many torrents have been added or removed. A function mutex_get_torrent_count
 has been introduced.

---
 opentracker.c   |  58 +++++--
 ot_clean.c      |   8 +-
 ot_fullscrape.c |   8 +-
 ot_http.c       |  14 +-
 ot_livesync.c   | 400 ++++++++++++++++++++++++++++++++++++++----------
 ot_livesync.h   |  26 ++--
 ot_mutex.c      |  16 +-
 ot_mutex.h      |   6 +-
 ot_stats.c      |  32 +---
 ot_udp.c        |  18 +--
 trackerlogic.c  |  89 ++++++-----
 trackerlogic.h  |  13 +-
 12 files changed, 476 insertions(+), 212 deletions(-)

diff --git a/opentracker.c b/opentracker.c
index 61acd3f..993877a 100644
--- a/opentracker.c
+++ b/opentracker.c
@@ -350,8 +350,47 @@ int parse_configfile( char * config_filename ) {
   return bound;
 }
 
-int main( int argc, char **argv ) {
+int drop_privileges (const char * const serverdir) {
   struct passwd *pws = NULL;
+
+  /* Grab pws entry before chrooting */
+  pws = getpwnam( "nobody" );
+  endpwent();
+
+  if( geteuid() == 0 ) {
+    /* Running as root: chroot and drop privileges */
+    if(chroot( serverdir )) {
+      fprintf( stderr, "Could not chroot to %s, because: %s\n", serverdir, strerror(errno) );
+      return -1;
+    }
+
+    if(chdir("/"))
+      panic("chdir() failed after chrooting: ");
+
+    if( !pws ) {
+      setegid( (gid_t)-2 ); setgid( (gid_t)-2 );
+      setuid( (uid_t)-2 );  seteuid( (uid_t)-2 );
+    }
+    else {
+      setegid( pws->pw_gid ); setgid( pws->pw_gid );
+      setuid( pws->pw_uid );  seteuid( pws->pw_uid );
+    }
+
+    if( geteuid() == 0 || getegid() == 0 )
+      panic("Still running with root privileges?!");
+  }
+  else {
+    /* Normal user, just chdir() */
+    if(chdir( serverdir )) {
+      fprintf( stderr, "Could not chroot to %s, because: %s\n", serverdir, strerror(errno) );
+      return -1;
+    }
+  }
+
+  return 0;
+}
+
+int main( int argc, char **argv ) {
   char serverip[4] = {0,0,0,0}, tmpip[4];
   int bound = 0, scanon = 1;
   uint16_t tmpport;
@@ -404,16 +443,8 @@ while( scanon ) {
     ot_try_bind( serverip, 6969, FLAG_UDP );
   }
 
-  /* Drop permissions */
-  pws = getpwnam( "nobody" );
-  if( !pws ) {
-    setegid( (gid_t)-2 ); setuid( (uid_t)-2 );
-    setgid( (gid_t)-2 ); seteuid( (uid_t)-2 );
-  } else {
-    setegid( pws->pw_gid ); setuid( pws->pw_uid );
-    setgid( pws->pw_gid ); seteuid( pws->pw_uid );
-  }
-  endpwent();
+  if( drop_privileges( g_serverdir ? g_serverdir : "." ) == -1 )
+    panic( "drop_privileges failed, exiting. Last error");
 
   signal( SIGPIPE, SIG_IGN );
   signal( SIGINT,  signal_handler );
@@ -421,9 +452,10 @@ while( scanon ) {
 
   g_now_seconds = time( NULL );
 
-  if( trackerlogic_init( g_serverdir ? g_serverdir : "." ) == -1 )
-    panic( "Logic not started" );
+  /* Init all sub systems. This call may fail with an exit() */
+  trackerlogic_init( );
 
+  /* Kick off our initial clock setting alarm */
   alarm(5);
 
   server_mainloop( );
diff --git a/ot_clean.c b/ot_clean.c
index 4adeee6..11c85ab 100644
--- a/ot_clean.c
+++ b/ot_clean.c
@@ -20,7 +20,7 @@
 static ssize_t clean_single_bucket( ot_peer *peers, size_t peer_count, time_t timedout, int *removed_seeders ) {
   ot_peer *last_peer = peers + peer_count, *insert_point;
   time_t timediff;
- 
+
   /* Two scan modes: unless there is one peer removed, just increase ot_peertime */
   while( peers < last_peer ) {
     if( ( timediff = timedout + OT_PEERTIME( peers ) ) >= OT_PEER_TIMEOUT )
@@ -105,17 +105,19 @@ static void * clean_worker( void * args ) {
     while( bucket-- ) {
       ot_vector *torrents_list = mutex_bucket_lock( bucket );
       size_t     toffs;
+      int        delta_torrentcount = 0;
 
       for( toffs=0; toffs<torrents_list->size; ++toffs ) {
         ot_torrent *torrent = ((ot_torrent*)(torrents_list->data)) + toffs;
         if( clean_single_torrent( torrent ) ) {
           vector_remove_torrent( torrents_list, torrent );
+          delta_torrentcount -= 1;
           --toffs; continue;
         }
       }
-      mutex_bucket_unlock( bucket );
+      mutex_bucket_unlock( bucket, delta_torrentcount );
       if( !g_opentracker_running )
-        return NULL;      
+        return NULL;
       usleep( OT_CLEAN_SLEEP );
     }
   }
diff --git a/ot_fullscrape.c b/ot_fullscrape.c
index 58546ca..3f60d40 100644
--- a/ot_fullscrape.c
+++ b/ot_fullscrape.c
@@ -152,7 +152,7 @@ static void fullscrape_make( int *iovec_entries, struct iovec **iovector, ot_tas
     /* Get exclusive access to that bucket */
     ot_vector *torrents_list = mutex_bucket_lock( bucket );
     size_t tor_offset;
-    
+
     /* For each torrent in this bucket.. */
     for( tor_offset=0; tor_offset<torrents_list->size; ++tor_offset ) {
       /* Address torrents members */
@@ -199,13 +199,13 @@ static void fullscrape_make( int *iovec_entries, struct iovec **iovector, ot_tas
       /* Check if there still is enough buffer left */
       while( r >= re )
        if( fullscrape_increase( iovec_entries, iovector, &r, &re WANT_COMPRESSION_GZIP_PARAM( &strm, mode, Z_NO_FLUSH ) ) )
-         return mutex_bucket_unlock( bucket );
+         return mutex_bucket_unlock( bucket, 0 );
 
       IF_COMPRESSION( r = compress_buffer; )
     }
 
     /* All torrents done: release lock on current bucket */
-    mutex_bucket_unlock( bucket );
+    mutex_bucket_unlock( bucket, 0 );
 
     /* Parent thread died? */
     if( !g_opentracker_running )
@@ -225,7 +225,7 @@ static void fullscrape_make( int *iovec_entries, struct iovec **iovector, ot_tas
 
     while( r >= re )
       if( fullscrape_increase( iovec_entries, iovector, &r, &re WANT_COMPRESSION_GZIP_PARAM( &strm, mode, Z_FINISH ) ) )
-        return mutex_bucket_unlock( bucket );
+        return mutex_bucket_unlock( bucket, 0 );
     deflateEnd(&strm);
   }
 #endif
diff --git a/ot_http.c b/ot_http.c
index d66fc80..4111d6b 100644
--- a/ot_http.c
+++ b/ot_http.c
@@ -385,7 +385,6 @@ static ssize_t http_handle_announce( const int64 client_socket, char *data ) {
   char       *c = data;
   int         numwant, tmp, scanon;
   ot_peer     peer;
-  ot_torrent *torrent;
   ot_hash    *hash = NULL;
   unsigned short port = htons(6881);
   ssize_t     len;
@@ -403,6 +402,10 @@ static ssize_t http_handle_announce( const int64 client_socket, char *data ) {
   numwant = 50;
   scanon = 1;
 
+#ifdef _DEBUG_PEERID
+  g_this_peerid_data = NULL;
+#endif
+
   while( scanon ) {
     switch( scan_urlencoded_query( &c, data = c, SCAN_SEARCHPATH_PARAM ) ) {
     case -2: scanon = 0; break;   /* TERMINATOR */
@@ -483,10 +486,11 @@ static ssize_t http_handle_announce( const int64 client_socket, char *data ) {
 
   if( OT_PEERFLAG( &peer ) & PEER_FLAG_STOPPED )
     len = remove_peer_from_torrent( hash, &peer, SUCCESS_HTTP_HEADER_LENGTH + static_outbuf, FLAG_TCP );
-  else {
-    torrent = add_peer_to_torrent( hash, &peer  WANT_SYNC_PARAM( 0 ) );
-    if( !torrent || !( len = return_peers_for_torrent( torrent, numwant, SUCCESS_HTTP_HEADER_LENGTH + static_outbuf, FLAG_TCP ) ) ) HTTPERROR_500;
-  }
+  else
+    len = add_peer_to_torrent_and_return_peers(hash, &peer, FLAG_TCP, numwant, SUCCESS_HTTP_HEADER_LENGTH + static_outbuf);
+
+  if( !len ) HTTPERROR_500;
+
   stats_issue_event( EVENT_ANNOUNCE, FLAG_TCP, len);
   return len;
 }
diff --git a/ot_livesync.c b/ot_livesync.c
index 3cad121..47a371a 100644
--- a/ot_livesync.c
+++ b/ot_livesync.c
@@ -9,59 +9,109 @@
 #include <string.h>
 #include <pthread.h>
 #include <unistd.h>
+#include <stdlib.h>
 
 /* Libowfat */
 #include "socket.h"
 #include "ndelay.h"
+#include "byte.h"
 
 /* Opentracker */
 #include "trackerlogic.h"
 #include "ot_livesync.h"
 #include "ot_accesslist.h"
 #include "ot_stats.h"
+#include "ot_mutex.h"
 
 #ifdef WANT_SYNC_LIVE
 
-char groupip_1[4] = { 224,0,23,42 };
+char groupip_1[4] = { 224,0,23,5 };
 
-#define LIVESYNC_BUFFINSIZE (256*256)
-#define LIVESYNC_BUFFSIZE  1504
-#define LIVESYNC_BUFFWATER (sizeof(ot_peer)+sizeof(ot_hash))
+#define LIVESYNC_INCOMING_BUFFSIZE          (256*256)
 
-#define LIVESYNC_MAXDELAY  15
+#define LIVESYNC_OUTGOING_BUFFSIZE_PEERS     1504
+#define LIVESYNC_OUTGOING_WATERMARK_PEERS   (sizeof(ot_peer)+sizeof(ot_hash))
+
+#ifdef WANT_SYNC_SCRAPE
+#define LIVESYNC_OUTGOING_BUFFSIZE_SCRAPE    1504
+#define LIVESYNC_OUTGOING_WATERMARK_SCRAPE  (sizeof(ot_hash)+sizeof(uint64_t)+sizeof(uint32_t))
+#define LIVESYNC_OUTGOING_MAXPACKETS_SCRAPE  100
+
+#define LIVESYNC_FIRST_BEACON_DELAY          (30*60) /* seconds */
+#define LIVESYNC_BEACON_INTERVAL             60      /* seconds */
+#define LIVESYNC_INQUIRE_THRESH              0.75
+#endif /* WANT_SYNC_SCRAPE */
+
+#define LIVESYNC_MAXDELAY                    15      /* seconds */
+
+enum { OT_SYNC_PEER
+#ifdef WANT_SYNC_SCRAPE
+  , OT_SYNC_SCRAPE_BEACON, OT_SYNC_SCRAPE_INQUIRE, OT_SYNC_SCRAPE_TELL
+#endif
+};
 
 /* Forward declaration */
 static void * livesync_worker( void * args );
 
 /* For outgoing packets */
-static int64 g_livesync_socket_in = -1;
+static int64    g_socket_in = -1;
 
 /* For incoming packets */
-static int64 g_livesync_socket_out = -1;
+static int64    g_socket_out = -1;
+static uint8_t  g_inbuffer[LIVESYNC_INCOMING_BUFFSIZE];
 
-static uint8_t  livesync_inbuffer[LIVESYNC_BUFFINSIZE];
-static uint8_t  livesync_outbuffer_start[ LIVESYNC_BUFFSIZE ];
-static uint8_t *livesync_outbuffer_pos;
-static uint8_t *livesync_outbuffer_highwater = livesync_outbuffer_start + LIVESYNC_BUFFSIZE - LIVESYNC_BUFFWATER;
-static ot_time  livesync_lastpacket_time;
+static uint8_t  g_peerbuffer_start[LIVESYNC_OUTGOING_BUFFSIZE_PEERS];
+static uint8_t *g_peerbuffer_pos;
+static uint8_t *g_peerbuffer_highwater = g_peerbuffer_start + LIVESYNC_OUTGOING_BUFFSIZE_PEERS - LIVESYNC_OUTGOING_WATERMARK_PEERS;
+
+static ot_time  g_next_packet_time;
+
+#ifdef WANT_SYNC_SCRAPE
+/* Live sync scrape buffers, states and timers */
+static ot_time  g_next_beacon_time;
+static ot_time  g_next_inquire_time;
+
+static uint8_t  g_scrapebuffer_start[LIVESYNC_OUTGOING_BUFFSIZE_SCRAPE];
+static uint8_t *g_scrapebuffer_pos;
+static uint8_t *g_scrapebuffer_highwater = g_scrapebuffer_start + LIVESYNC_OUTGOING_BUFFSIZE_SCRAPE - LIVESYNC_OUTGOING_WATERMARK_SCRAPE;
+
+static size_t   g_inquire_remote_count;
+static uint32_t g_inquire_remote_host;
+static int      g_inquire_inprogress;
+static int      g_inquire_bucket;
+#endif /* WANT_SYNC_SCRAPE */
 
 static pthread_t thread_id;
 void livesync_init( ) {
-  if( g_livesync_socket_in == -1 )
+  if( g_socket_in == -1 )
     exerr( "No socket address for live sync specified." );
-  livesync_outbuffer_pos = livesync_outbuffer_start;
-  memmove( livesync_outbuffer_pos, &g_tracker_id, sizeof( g_tracker_id ) );
-  livesync_outbuffer_pos += sizeof( g_tracker_id );
-  livesync_lastpacket_time = g_now_seconds;
+
+  /* Prepare outgoing peers buffer */
+  g_peerbuffer_pos = g_peerbuffer_start;
+  memmove( g_peerbuffer_pos, &g_tracker_id, sizeof( g_tracker_id ) );
+  uint32_pack_big( (char*)g_peerbuffer_pos + sizeof( g_tracker_id ), OT_SYNC_PEER);
+  g_peerbuffer_pos += sizeof( g_tracker_id ) + sizeof( uint32_t);
+
+#ifdef WANT_SYNC_SCRAPE
+  /* Prepare outgoing scrape buffer */
+  g_scrapebuffer_pos = g_scrapebuffer_start;
+  memmove( g_scrapebuffer_pos, &g_tracker_id, sizeof( g_tracker_id ) );
+  uint32_pack_big( (char*)g_scrapebuffer_pos + sizeof( g_tracker_id ), OT_SYNC_SCRAPE_TELL);
+  g_scrapebuffer_pos += sizeof( g_tracker_id ) + sizeof( uint32_t);
+
+  /* Wind up timers for inquires */
+  g_next_beacon_time = g_now_seconds + LIVESYNC_FIRST_BEACON_DELAY;
+#endif /* WANT_SYNC_SCRAPE */
+  g_next_packet_time = g_now_seconds + LIVESYNC_MAXDELAY;
 
   pthread_create( &thread_id, NULL, livesync_worker, NULL );
 }
 
 void livesync_deinit() {
-  if( g_livesync_socket_in != -1 )
-    close( g_livesync_socket_in );
-  if( g_livesync_socket_out != -1 )
-    close( g_livesync_socket_out );
+  if( g_socket_in != -1 )
+    close( g_socket_in );
+  if( g_socket_out != -1 )
+    close( g_socket_out );
 
   pthread_cancel( thread_id );
 }
@@ -69,104 +119,292 @@ void livesync_deinit() {
 void livesync_bind_mcast( char *ip, uint16_t port) {
   char tmpip[4] = {0,0,0,0};
 
-  if( g_livesync_socket_in != -1 )
+  if( g_socket_in != -1 )
     exerr("Error: Livesync listen ip specified twice.");
 
-  if( ( g_livesync_socket_in = socket_udp4( )) < 0)
+  if( ( g_socket_in = socket_udp4( )) < 0)
     exerr("Error: Cant create live sync incoming socket." );
-  ndelay_off(g_livesync_socket_in);
+  ndelay_off(g_socket_in);
 
-  if( socket_bind4_reuse( g_livesync_socket_in, tmpip, port ) == -1 )
+  if( socket_bind4_reuse( g_socket_in, tmpip, port ) == -1 )
     exerr("Error: Cant bind live sync incoming socket." );
 
-  if( socket_mcjoin4( g_livesync_socket_in, groupip_1, ip ) )
+  if( socket_mcjoin4( g_socket_in, groupip_1, ip ) )
     exerr("Error: Cant make live sync incoming socket join mcast group.");
 
-  if( ( g_livesync_socket_out = socket_udp4()) < 0)
+  if( ( g_socket_out = socket_udp4()) < 0)
     exerr("Error: Cant create live sync outgoing socket." );
-  if( socket_bind4_reuse( g_livesync_socket_out, ip, port ) == -1 )
+  if( socket_bind4_reuse( g_socket_out, ip, port ) == -1 )
     exerr("Error: Cant bind live sync outgoing socket." );
 
-  socket_mcttl4(g_livesync_socket_out, 1);
-  socket_mcloop4(g_livesync_socket_out, 0);
+  socket_mcttl4(g_socket_out, 1);
+  socket_mcloop4(g_socket_out, 0);
 }
 
-static void livesync_issuepacket( ) {
-  socket_send4(g_livesync_socket_out, (char*)livesync_outbuffer_start, livesync_outbuffer_pos - livesync_outbuffer_start,
+static void livesync_issue_peersync( ) {
+  socket_send4(g_socket_out, (char*)g_peerbuffer_start, g_peerbuffer_pos - g_peerbuffer_start,
                groupip_1, LIVESYNC_PORT);
-  livesync_outbuffer_pos = livesync_outbuffer_start + sizeof( g_tracker_id );
-  livesync_lastpacket_time = g_now_seconds;
+  g_peerbuffer_pos   = g_peerbuffer_start + sizeof( g_tracker_id ) + sizeof( uint32_t );
+  g_next_packet_time = g_now_seconds + LIVESYNC_MAXDELAY;
 }
 
-/* Inform live sync about whats going on. */
-void livesync_tell( ot_hash * const info_hash, const ot_peer * const peer ) {
-  int i;
-  for(i=0;i<20;i+=4) WRITE32(livesync_outbuffer_pos,i,READ32(info_hash,i));
-  WRITE32(livesync_outbuffer_pos,20,READ32(peer,0));
-  WRITE32(livesync_outbuffer_pos,24,READ32(peer,4));
-  livesync_outbuffer_pos += 28;
-
-  if( livesync_outbuffer_pos >= livesync_outbuffer_highwater )
-    livesync_issuepacket();
+static void livesync_handle_peersync( ssize_t datalen ) {
+  int off = sizeof( g_tracker_id ) + sizeof( uint32_t );
+
+  /* Now basic sanity checks have been done on the live sync packet
+     We might add more testing and logging. */
+  while( off + (ssize_t)sizeof( ot_hash ) + (ssize_t)sizeof( ot_peer ) <= datalen ) {
+    ot_peer *peer = (ot_peer*)(g_inbuffer + off + sizeof(ot_hash));
+    ot_hash *hash = (ot_hash*)(g_inbuffer + off);
+
+    if( !g_opentracker_running ) return;
+
+    if( OT_PEERFLAG(peer) & PEER_FLAG_STOPPED )
+      remove_peer_from_torrent(hash, peer, NULL, FLAG_MCA );
+    else
+      add_peer_to_torrent( hash, peer, FLAG_MCA );
+
+    off += sizeof( ot_hash ) + sizeof( ot_peer );
+  }
+
+  stats_issue_event(EVENT_SYNC, 0, datalen / ((ssize_t)sizeof( ot_hash ) + (ssize_t)sizeof( ot_peer )));
 }
 
+#ifdef WANT_SYNC_SCRAPE
+void livesync_issue_beacon( ) {
+  size_t torrent_count = mutex_get_torrent_count();
+  uint8_t beacon[ sizeof(g_tracker_id) + sizeof(uint32_t) + sizeof( uint64_t ) ];
+
+  memmove( beacon, &g_tracker_id, sizeof( g_tracker_id ) );
+  uint32_pack_big( (char*)beacon + sizeof( g_tracker_id ), OT_SYNC_SCRAPE_BEACON);
+  uint32_pack_big( (char*)beacon + sizeof( g_tracker_id ) +     sizeof(uint32_t), (uint32_t)((uint64_t)(torrent_count)>>32) );
+  uint32_pack_big( (char*)beacon + sizeof( g_tracker_id ) + 2 * sizeof(uint32_t), (uint32_t)torrent_count );
+
+  socket_send4(g_socket_out, (char*)beacon, sizeof(beacon), groupip_1, LIVESYNC_PORT);
+}
+
+void livesync_handle_beacon( ssize_t datalen ) {
+  size_t torrent_count_local, torrent_count_remote;
+  if( datalen != sizeof(g_tracker_id) + sizeof(uint32_t) + sizeof( uint64_t ) )
+    return;
+  torrent_count_local   = mutex_get_torrent_count();
+  torrent_count_remote  = (size_t)(((uint64_t)uint32_read_big((char*)g_inbuffer+sizeof( g_tracker_id ) + sizeof(uint32_t))) << 32);
+  torrent_count_remote |= (size_t)uint32_read_big((char*)g_inbuffer+sizeof( g_tracker_id ) + 2 * sizeof(uint32_t));
+
+  /* Empty tracker is useless */
+  if( !torrent_count_remote ) return;
+
+  if( ((double)torrent_count_local ) / ((double)torrent_count_remote) < LIVESYNC_INQUIRE_THRESH) {
+    if( !g_next_inquire_time ) {
+      g_next_inquire_time    = g_now_seconds + 2 * LIVESYNC_BEACON_INTERVAL;
+      g_inquire_remote_count = 0;
+    }
+
+    if( torrent_count_remote > g_inquire_remote_count ) {
+      g_inquire_remote_count = torrent_count_remote;
+      memmove( &g_inquire_remote_host, g_inbuffer, sizeof( g_tracker_id ) );
+    }
+  }
+}
+
+void livesync_issue_inquire( ) {
+  uint8_t inquire[ sizeof(g_tracker_id) + sizeof(uint32_t) + sizeof(g_tracker_id)];
+
+  memmove( inquire, &g_tracker_id, sizeof( g_tracker_id ) );
+  uint32_pack_big( (char*)inquire + sizeof( g_tracker_id ), OT_SYNC_SCRAPE_INQUIRE);
+  memmove( inquire + sizeof(g_tracker_id) + sizeof(uint32_t), &g_inquire_remote_host, sizeof( g_tracker_id ) );
+
+  socket_send4(g_socket_out, (char*)inquire, sizeof(inquire), groupip_1, LIVESYNC_PORT);
+}
+
+void livesync_handle_inquire( ssize_t datalen ) {
+  if( datalen != sizeof(g_tracker_id) + sizeof(uint32_t) + sizeof(g_tracker_id) )
+    return;
+
+  /* If it isn't us, they're inquiring, ignore inquiry */
+  if( memcmp( &g_tracker_id, g_inbuffer, sizeof( g_tracker_id ) ) )
+    return;
+
+  /* Start scrape tell on next ticker */
+  if( !g_inquire_inprogress ) {
+    g_inquire_inprogress = 1;
+    g_inquire_bucket     = 0;
+  }
+}
+
+void livesync_issue_tell( ) {
+  int packets_to_send = LIVESYNC_OUTGOING_MAXPACKETS_SCRAPE;
+  while( packets_to_send > 0 && g_inquire_bucket < OT_BUCKET_COUNT ) {
+    ot_vector *torrents_list = mutex_bucket_lock( g_inquire_bucket );
+    unsigned int j;
+    for( j=0; j<torrents_list->size; ++j ) {
+      ot_torrent *torrent = (ot_torrent*)(torrents_list->data) + j;
+      memmove(g_scrapebuffer_pos, torrent->hash, sizeof(ot_hash));
+      g_scrapebuffer_pos += sizeof(ot_hash);
+      uint32_pack_big( (char*)g_scrapebuffer_pos    , (uint32_t)(g_now_minutes - torrent->peer_list->base ));
+      uint32_pack_big( (char*)g_scrapebuffer_pos + 4, (uint32_t)((uint64_t)(torrent->peer_list->down_count)>>32) );
+      uint32_pack_big( (char*)g_scrapebuffer_pos + 8, (uint32_t)torrent->peer_list->down_count );
+      g_scrapebuffer_pos += 12;
+
+      if( g_scrapebuffer_pos >= g_scrapebuffer_highwater ) {
+        socket_send4(g_socket_out, (char*)g_scrapebuffer_start, g_scrapebuffer_pos - g_scrapebuffer_start, groupip_1, LIVESYNC_PORT);
+        g_scrapebuffer_pos = g_scrapebuffer_start + sizeof( g_tracker_id ) + sizeof( uint32_t);
+        --packets_to_send;
+      }
+    }
+    mutex_bucket_unlock( g_inquire_bucket++, 0 );
+    if( !g_opentracker_running )
+      return;
+  }
+  if( g_inquire_bucket == OT_BUCKET_COUNT ) {
+    socket_send4(g_socket_out, (char*)g_scrapebuffer_start, g_scrapebuffer_pos - g_scrapebuffer_start, groupip_1, LIVESYNC_PORT);
+    g_inquire_inprogress = 0;
+  }
+}
+
+void livesync_handle_tell( ssize_t datalen ) {
+  int off = sizeof( g_tracker_id ) + sizeof( uint32_t );
+
+  /* Some instance is in progress of telling. Our inquiry was successful.
+     Don't ask again until we see next beacon. */
+  g_next_inquire_time = 0;
+  
+  /* Don't cause any new inquiries during another tracker's tell */
+  if( g_next_beacon_time - g_now_seconds < LIVESYNC_BEACON_INTERVAL )
+    g_next_beacon_time = g_now_seconds + LIVESYNC_BEACON_INTERVAL;
+
+  while( off + sizeof(ot_hash) + 12 <= (size_t)datalen ) {
+    ot_hash *hash = (ot_hash*)(g_inbuffer+off);
+    ot_vector *torrents_list = mutex_bucket_lock_by_hash(hash);
+    size_t     down_count_remote;
+    int exactmatch;
+    ot_torrent * torrent = vector_find_or_insert(torrents_list, hash, sizeof(ot_hash), OT_HASH_COMPARE_SIZE, &exactmatch);
+    if( !torrent ) {
+      mutex_bucket_unlock_by_hash( hash, 0 );
+      continue;
+    }
+
+    if( !exactmatch ) {
+      /* Create a new torrent entry, then */
+      int i; for(i=0;i<20;i+=4) WRITE32(&torrent->hash,i,READ32(hash,i));
+
+      if( !( torrent->peer_list = malloc( sizeof (ot_peerlist) ) ) ) {
+        vector_remove_torrent( torrents_list, torrent );
+        mutex_bucket_unlock_by_hash( hash, 0 );
+        continue;
+      }
+
+      byte_zero( torrent->peer_list, sizeof( ot_peerlist ) );
+      torrent->peer_list->base = g_now_minutes - uint32_read_big((char*)g_inbuffer+off+sizeof(ot_hash));
+    }
+
+    down_count_remote  = (size_t)(((uint64_t)uint32_read_big((char*)g_inbuffer+off+sizeof( ot_hash ) +     sizeof(uint32_t))) << 32);
+    down_count_remote |= (size_t)            uint32_read_big((char*)g_inbuffer+off+sizeof( ot_hash ) + 2 * sizeof(uint32_t));
+
+    if( down_count_remote > torrent->peer_list->down_count )
+      torrent->peer_list->down_count = down_count_remote;
+    /* else
+      We might think of sending a tell packet, if we have a much larger downloaded count
+     */
+
+    mutex_bucket_unlock( g_inquire_bucket++, exactmatch?0:1 );
+    if( !g_opentracker_running )
+      return;
+    off += sizeof(ot_hash) + 12;
+  }
+}
+#endif /* WANT_SYNC_SCRAPE */
+
 /* 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 */
+   stuck when there's not enough traffic to fill udp packets fast
+   enough */
 void livesync_ticker( ) {
-  if( ( g_now_seconds - livesync_lastpacket_time > LIVESYNC_MAXDELAY) &&
-      ( livesync_outbuffer_pos > livesync_outbuffer_start + sizeof( g_tracker_id ) ) )
-    livesync_issuepacket();
+  
+  /* livesync_issue_peersync sets g_next_packet_time */
+  if( g_now_seconds > g_next_packet_time &&
+     g_peerbuffer_pos > g_peerbuffer_start + sizeof( g_tracker_id ) )
+    livesync_issue_peersync();
+
+#ifdef WANT_SYNC_SCRAPE
+  /* Send first beacon after running at least LIVESYNC_FIRST_BEACON_DELAY
+     seconds and not more often than every LIVESYNC_BEACON_INTERVAL seconds */
+  if( g_now_seconds > g_next_beacon_time ) {
+    livesync_issue_beacon( );
+    g_next_beacon_time = g_now_seconds + LIVESYNC_BEACON_INTERVAL;
+  }
+
+  /* If we're interested in an inquiry and waited long enough to see all
+     tracker's beacons, go ahead and inquire */
+  if( g_next_inquire_time && g_now_seconds > g_next_inquire_time ) {
+    livesync_issue_inquire();
+
+    /* If packet gets lost, ask again after LIVESYNC_BEACON_INTERVAL */
+    g_next_inquire_time = g_now_seconds + LIVESYNC_BEACON_INTERVAL;
+  }
+
+  /* If we're in process of telling, let's tell. */
+  if( g_inquire_inprogress )
+    livesync_issue_tell( );
+
+#endif /* WANT_SYNC_SCRAPE */
+}
+
+/* Inform live sync about whats going on. */
+void livesync_tell( ot_hash * const info_hash, const ot_peer * const peer ) {
+  unsigned int i;
+  for(i=0;i<sizeof(ot_hash)/4;i+=4) WRITE32(g_peerbuffer_pos,i,READ32(info_hash,i));
+
+  WRITE32(g_peerbuffer_pos,sizeof(ot_hash)  ,READ32(peer,0));
+  WRITE32(g_peerbuffer_pos,sizeof(ot_hash)+4,READ32(peer,4));
+
+  g_peerbuffer_pos += sizeof(ot_hash)+8;
+
+  if( g_peerbuffer_pos >= g_peerbuffer_highwater )
+    livesync_issue_peersync();
 }
 
 static void * livesync_worker( void * args ) {
   uint8_t in_ip[4]; uint16_t in_port;
   ssize_t datalen;
-  int off;
 
-  args = args;
+  (void)args;
 
   while( 1 ) {
-    datalen = socket_recv4(g_livesync_socket_in, (char*)livesync_inbuffer, LIVESYNC_BUFFINSIZE, (char*)in_ip, &in_port);
-    off = 4;
+    datalen = socket_recv4(g_socket_in, (char*)g_inbuffer, LIVESYNC_INCOMING_BUFFSIZE, (char*)in_ip, &in_port);
 
-    if( datalen <= 0 )
+    /* Expect at least tracker id and packet type */
+    if( datalen <= (ssize_t)(sizeof( g_tracker_id ) + sizeof( uint32_t )) )
       continue;
-
-    if( datalen < (ssize_t)(sizeof( g_tracker_id ) + sizeof( ot_hash ) + sizeof( ot_peer ) ) ) {
-      /* TODO: log invalid sync packet */
+    if( !accesslist_isblessed((char*)in_ip, OT_PERMISSION_MAY_LIVESYNC))
       continue;
-    }
-
-    if( !accesslist_isblessed((char*)in_ip, OT_PERMISSION_MAY_LIVESYNC)) {
-      /* TODO: log invalid sync packet */
-      continue;
-    }
-
-    if( !memcmp( livesync_inbuffer, &g_tracker_id, sizeof( g_tracker_id ) ) ) {
+    if( !memcmp( g_inbuffer, &g_tracker_id, sizeof( g_tracker_id ) ) ) {
       /* TODO: log packet coming from ourselves */
       continue;
     }
 
-    /* Now basic sanity checks have been done on the live sync packet
-       We might add more testing and logging. */
-    while( off + (ssize_t)sizeof( ot_hash ) + (ssize_t)sizeof( ot_peer ) <= datalen ) {
-      ot_peer *peer = (ot_peer*)(livesync_inbuffer + off + sizeof(ot_hash));
-      ot_hash *hash = (ot_hash*)(livesync_inbuffer + off);
-
-      if( !g_opentracker_running )
-        return NULL;
-
-      if( OT_PEERFLAG(peer) & PEER_FLAG_STOPPED )
-        remove_peer_from_torrent(hash, peer, NULL, FLAG_MCA);
-      else
-        add_peer_to_torrent( hash, peer  WANT_SYNC_PARAM(1));
-
-      off += sizeof( ot_hash ) + sizeof( ot_peer );
+    switch( uint32_read_big( (char*)g_inbuffer ) ) {
+    case OT_SYNC_PEER:
+      livesync_handle_peersync( datalen );
+      break;
+#ifdef WANT_SYNC_SCRAPE
+    case OT_SYNC_SCRAPE_BEACON:
+      livesync_handle_beacon( datalen );
+      break;
+    case OT_SYNC_SCRAPE_INQUIRE:
+      livesync_handle_inquire( datalen );
+      break;
+    case OT_SYNC_SCRAPE_TELL:
+      livesync_handle_tell( datalen );
+      break;
+#endif /* WANT_SYNC_SCRAPE */
+    default:
+      break;
     }
 
-    stats_issue_event(EVENT_SYNC, 0, datalen / ((ssize_t)sizeof( ot_hash ) + (ssize_t)sizeof( ot_peer )));
+    /* Handle outstanding requests */
+    livesync_ticker( );
   }
+
   /* Never returns. */
   return NULL;
 }
diff --git a/ot_livesync.h b/ot_livesync.h
index 97fe803..ae9ab55 100644
--- a/ot_livesync.h
+++ b/ot_livesync.h
@@ -38,25 +38,22 @@
                                ########
  ######## SCRAPE SYNC PROTOCOL ########
  ########
- 
-  Each tracker instance SHOULD broadcast a beacon once in every 5 minutes after
-  running at least 30 minutes:
+
+  Each tracker instance SHOULD broadcast a beacon every LIVESYNC_BEACON_INTERVAL
+  seconds after running at least LIVESYNC_FIRST_BEACON_DELAY seconds:
 
   packet type SYNC_SCRAPE_BEACON
   [ 0x0008 0x08 amount of torrents served
   ]
 
   If a tracker instance receives a beacon from another instance that has more than
-  twice its torrent count, it asks for a scrape. It must wait for at least 5 + 1
-  minutes in order to inspect beacons from all tracker instances and chose the one
-  with most torrents.
+  its torrent count plus a threshold, it inquires for a scrape. It must wait for at
+  least 2 * LIVESYNC_BEACON_INTERVAL seconds in order to inspect beacons from all
+  tracker instances and inquire only the one with most torrents.
 
   If it sees a SYNC_SCRAPE_TELL within that time frame, it's likely, that another
-  scrape sync is going on. So one tracker instance MUST NOT react to beacons within
-  5 minutes of last seeing a SYNC_SCRAPE_TELL packet. After a scrape sync all
-  tracker instances have updated their torrents, so an instance in a "want inquire"
-  state should wait for the next round of beacons to chose the tracker with most
-  data again.
+  scrape sync is going on. It should reset its state to needs no inquiry. It should
+  be reenabled on the next beacon, if still needed.
 
   packet type SYNC_SCRAPE_INQUIRE
   [ 0x0008 0x04 id of tracker instance to inquire
@@ -64,16 +61,17 @@
 
   The inquired tracker instance answers with as many scrape tell packets it needs
   to deliver stats about all its torrents
- 
+
   packet type SYNC_SCRAPE_TELL
   [ 0x0008 0x14 info_hash
     0x001c 0x04 base offset (i.e. when was it last announced, in minutes)
     0x0020 0x08 downloaded count
   ]*
 
-  Each tracker instance that receives a scrape tell, looks up each torrent and
+  Each tracker instance that receives a SYNC_SCRAPE_TELL, looks up each torrent and
   compares downloaded count with its own counter. It can send out its own scrape
-  tell packets, if it knows more.
+  tell packets, if it knows more. However to not interrupt a scrape tell, a tracker
+  should wait LIVESYNC_BEACON_INTERVAL after receiving a scrape tell.
 
 */
 
diff --git a/ot_mutex.c b/ot_mutex.c
index a28144b..8094e99 100644
--- a/ot_mutex.c
+++ b/ot_mutex.c
@@ -24,6 +24,7 @@
 
 /* Our global all torrents list */
 static ot_vector all_torrents[OT_BUCKET_COUNT];
+static size_t    g_torrent_count;
 
 /* Bucket Magic */
 static int bucket_locklist[ OT_MAX_THREADS ];
@@ -87,15 +88,24 @@ ot_vector *mutex_bucket_lock_by_hash( ot_hash *hash ) {
   return all_torrents + bucket;
 }
 
-void mutex_bucket_unlock( int bucket ) {
+void mutex_bucket_unlock( int bucket, int delta_torrentcount ) {
   pthread_mutex_lock( &bucket_mutex );
   bucket_remove( bucket );
+  g_torrent_count += delta_torrentcount;
   pthread_cond_broadcast( &bucket_being_unlocked );
   pthread_mutex_unlock( &bucket_mutex );
 }
 
-void mutex_bucket_unlock_by_hash( ot_hash *hash ) {
-  mutex_bucket_unlock( uint32_read_big( (char*)*hash ) >> OT_BUCKET_COUNT_SHIFT );
+void mutex_bucket_unlock_by_hash( ot_hash *hash, int delta_torrentcount ) {
+  mutex_bucket_unlock( uint32_read_big( (char*)*hash ) >> OT_BUCKET_COUNT_SHIFT, delta_torrentcount );
+}
+
+size_t mutex_get_torrent_count( ) {
+  size_t torrent_count;
+  pthread_mutex_lock( &bucket_mutex );
+  torrent_count = g_torrent_count;
+  pthread_mutex_unlock( &bucket_mutex );
+  return torrent_count;
 }
 
 /* TaskQueue Magic */
diff --git a/ot_mutex.h b/ot_mutex.h
index 7038332..ba5684d 100644
--- a/ot_mutex.h
+++ b/ot_mutex.h
@@ -14,8 +14,10 @@ void mutex_deinit( );
 ot_vector *mutex_bucket_lock( int bucket );
 ot_vector *mutex_bucket_lock_by_hash( ot_hash *hash );
 
-void mutex_bucket_unlock( int bucket );
-void mutex_bucket_unlock_by_hash( ot_hash *hash );
+void mutex_bucket_unlock( int bucket, int delta_torrentcount );
+void mutex_bucket_unlock_by_hash( ot_hash *hash, int delta_torrentcount );
+
+size_t mutex_get_torrent_count();
 
 typedef enum {
   TASK_STATS_CONNS                 = 0x0001,
diff --git a/ot_stats.c b/ot_stats.c
index a4596c6..dbab275 100644
--- a/ot_stats.c
+++ b/ot_stats.c
@@ -187,7 +187,7 @@ size_t stats_top10_txt( char * reply ) {
         top10s[idx].torrent = (ot_torrent*)(torrents_list->data) + j;
       }
     }
-    mutex_bucket_unlock( bucket );
+    mutex_bucket_unlock( bucket, 0 );
     if( !g_opentracker_running )
       return 0;
   }
@@ -241,7 +241,7 @@ static size_t stats_slash24s_txt( char * reply, size_t amount, uint32_t thresh )
           if( !count ) {
             count = malloc( sizeof(uint32_t) * NUM_S24S );
             if( !count ) {
-              mutex_bucket_unlock( bucket );
+              mutex_bucket_unlock( bucket, 0 );
               goto bailout_cleanup;
             }
             byte_zero( count, sizeof( uint32_t ) * NUM_S24S );
@@ -251,7 +251,7 @@ static size_t stats_slash24s_txt( char * reply, size_t amount, uint32_t thresh )
         }
       }
     }
-    mutex_bucket_unlock( bucket );
+    mutex_bucket_unlock( bucket, 0 );
     if( !g_opentracker_running )
       goto bailout_cleanup;
   }
@@ -384,7 +384,7 @@ static size_t stats_peers_mrtg( char * reply ) {
       ot_peerlist *peer_list = ( ((ot_torrent*)(torrents_list->data))[j] ).peer_list;
       peer_count += peer_list->peer_count; seed_count += peer_list->seed_count;
     }
-    mutex_bucket_unlock( bucket );
+    mutex_bucket_unlock( bucket, 0 );
     if( !g_opentracker_running )
       return 0;
   }
@@ -397,17 +397,7 @@ static size_t stats_peers_mrtg( char * reply ) {
 
 static size_t stats_startstop_mrtg( char * reply )
 {
-  size_t    torrent_count = 0;
-  int bucket;
-
-  for( bucket=0; bucket<OT_BUCKET_COUNT; ++bucket )
-  {
-    ot_vector *torrents_list = mutex_bucket_lock( bucket );
-    torrent_count += torrents_list->size;
-    mutex_bucket_unlock( bucket );
-    if( !g_opentracker_running )
-      return 0;
-  }
+  size_t    torrent_count = mutex_get_torrent_count();
 
   return sprintf( reply, "%zd\n%zd\nopentracker handling %zd torrents\nopentracker",
     (size_t)0,
@@ -429,7 +419,7 @@ static size_t stats_toraddrem_mrtg( char * reply )
       ot_peerlist *peer_list = ( ((ot_torrent*)(torrents_list->data))[j] ).peer_list;
       peer_count += peer_list->peer_count;
     }
-    mutex_bucket_unlock( bucket );
+    mutex_bucket_unlock( bucket, 0 );
     if( !g_opentracker_running )
       return 0;
   }
@@ -443,15 +433,7 @@ static size_t stats_toraddrem_mrtg( char * reply )
 
 static size_t stats_torrents_mrtg( char * reply )
 {
-  size_t torrent_count = 0;
-  int bucket;
-
-  for( bucket=0; bucket<OT_BUCKET_COUNT; ++bucket )
-  {
-    ot_vector *torrents_list = mutex_bucket_lock( bucket );
-    torrent_count += torrents_list->size;
-    mutex_bucket_unlock( bucket );
-  }
+  size_t torrent_count = mutex_get_torrent_count();
 
   return sprintf( reply, "%zd\n%zd\nopentracker serving %zd torrents\nopentracker",
     torrent_count,
diff --git a/ot_udp.c b/ot_udp.c
index 8f55963..fb171e7 100644
--- a/ot_udp.c
+++ b/ot_udp.c
@@ -41,7 +41,6 @@ static int udp_test_connectionid( const uint32_t * const connid, const char * re
 /* UDP implementation according to http://xbtt.sourceforge.net/udp_tracker_protocol.html */
 void handle_udp4( int64 serversocket ) {
   ot_peer     peer;
-  ot_torrent *torrent;
   ot_hash    *hash = NULL;
   char        remoteip[4];
   uint32_t   *inpacket = (uint32_t*)static_inbuf;
@@ -79,7 +78,7 @@ void handle_udp4( int64 serversocket ) {
       if( r < 98 )
         return;
 
-        if( !udp_test_connectionid( inpacket, remoteip ))
+      if( !udp_test_connectionid( inpacket, remoteip ))
         fprintf( stderr, "UDP connect Connection id missmatch.\n" );
 
       /* We do only want to know, if it is zero */
@@ -110,20 +109,15 @@ void handle_udp4( int64 serversocket ) {
 
       if( OT_PEERFLAG( &peer ) & PEER_FLAG_STOPPED ) /* Peer is gone. */
         r = remove_peer_from_torrent( hash, &peer, static_outbuf, FLAG_UDP );
-      else {
-        torrent = add_peer_to_torrent( hash, &peer  WANT_SYNC_PARAM( 0 ) );
-        if( !torrent )
-          return; /* XXX maybe send error */
-
-        r = 8 + return_peers_for_torrent( torrent, numwant, static_outbuf + 8, FLAG_UDP );
-      }
+      else
+        r = 8 + add_peer_to_torrent_and_return_peers( hash, &peer, FLAG_UDP, numwant, static_outbuf + 8 );
 
       socket_send4( serversocket, static_outbuf, r, remoteip, remoteport );
       stats_issue_event( EVENT_ANNOUNCE, FLAG_UDP, r );
       break;
 
     case 2: /* This is a scrape action */
-        if( !udp_test_connectionid( inpacket, remoteip ))
+      if( !udp_test_connectionid( inpacket, remoteip ))
         fprintf( stderr, "UDP scrape Connection id missmatch.\n" );
 
       outpacket[0] = htonl( 2 );    /* scrape action */
@@ -138,4 +132,8 @@ void handle_udp4( int64 serversocket ) {
   }
 }
 
+void udp_init( ) {
+
+}
+
 const char *g_version_udp_c = "$Source$: $Revision$\n";
diff --git a/trackerlogic.c b/trackerlogic.c
index 34a12e7..38be9f7 100644
--- a/trackerlogic.c
+++ b/trackerlogic.c
@@ -25,6 +25,9 @@
 #include "ot_fullscrape.h"
 #include "ot_livesync.h"
 
+/* Forward declaration */
+size_t return_peers_for_torrent( ot_torrent *torrent, size_t amount, char *reply, PROTO_FLAG proto );
+
 void free_peerlist( ot_peerlist *peer_list ) {
   if( peer_list->peers.data ) {
     if( OT_PEERLIST_HASBUCKETS( peer_list ) ) {
@@ -43,34 +46,36 @@ extern size_t g_this_peerid_len;
 extern char  *g_this_peerid_data;
 #endif
 
-ot_torrent *add_peer_to_torrent( ot_hash *hash, ot_peer *peer  WANT_SYNC_PARAM( int from_sync ) ) {
-  int         exactmatch;
+size_t add_peer_to_torrent_and_return_peers( ot_hash *hash, ot_peer *peer, PROTO_FLAG proto, size_t amount, char * reply ) {
+  int         exactmatch, delta_torrentcount = 0;
+  size_t      reply_size;
   ot_torrent *torrent;
   ot_peer    *peer_dest;
   ot_vector  *torrents_list = mutex_bucket_lock_by_hash( hash );
 
   if( !accesslist_hashisvalid( hash ) ) {
-    mutex_bucket_unlock_by_hash( hash );
-    return NULL;
+    mutex_bucket_unlock_by_hash( hash, 0 );
+    return 0;
   }
 
   torrent = vector_find_or_insert( torrents_list, (void*)hash, sizeof( ot_torrent ), OT_HASH_COMPARE_SIZE, &exactmatch );
   if( !torrent ) {
-    mutex_bucket_unlock_by_hash( hash );
-    return NULL;
+    mutex_bucket_unlock_by_hash( hash, 0 );
+    return 0;
   }
 
   if( !exactmatch ) {
     /* Create a new torrent entry, then */
     int i; for(i=0;i<20;i+=4) WRITE32(&torrent->hash,i,READ32(hash,i));
-    
+
     if( !( torrent->peer_list = malloc( sizeof (ot_peerlist) ) ) ) {
       vector_remove_torrent( torrents_list, torrent );
-      mutex_bucket_unlock_by_hash( hash );
-      return NULL;
+      mutex_bucket_unlock_by_hash( hash, 0 );
+      return 0;
     }
 
     byte_zero( torrent->peer_list, sizeof( ot_peerlist ) );
+    delta_torrentcount = 1;
   } else
     clean_single_torrent( torrent );
 
@@ -79,8 +84,8 @@ ot_torrent *add_peer_to_torrent( ot_hash *hash, ot_peer *peer  WANT_SYNC_PARAM(
   /* Check for peer in torrent */
   peer_dest = vector_find_or_insert_peer( &(torrent->peer_list->peers), peer, &exactmatch );
   if( !peer_dest ) {
-    mutex_bucket_unlock_by_hash( hash );
-    return NULL;
+    mutex_bucket_unlock_by_hash( hash, delta_torrentcount );
+    return 0;
   }
 
   /* Tell peer that it's fresh */
@@ -94,7 +99,7 @@ ot_torrent *add_peer_to_torrent( ot_hash *hash, ot_peer *peer  WANT_SYNC_PARAM(
   if( !exactmatch ) {
 
 #ifdef WANT_SYNC_LIVE
-    if( !from_sync )
+    if( proto == FLAG_MCA )
       livesync_tell( hash, peer );
     else
       OT_PEERFLAG( peer ) |= PEER_FLAG_FROM_SYNC;
@@ -118,17 +123,17 @@ ot_torrent *add_peer_to_torrent( ot_hash *hash, ot_peer *peer  WANT_SYNC_PARAM(
       printf( " %d.%d.%d.%d:%d\t%d %02X %s\n", _ip[0], _ip[1], _ip[2], _ip[3], OT_PEERTIME( peer_dest ), *(uint16_t*)( ((char*)peer_dest)+4 ), OT_PEERFLAG(peer_dest), g_this_peerid_data ? g_this_peerid_data : "-" );
     }
 #endif
-    
+
 #ifdef WANT_SYNC_LIVE
     /* Won't live sync peers that come back too fast. Only exception:
        fresh "completed" reports */
-    if( !from_sync ) {
+    if( proto != FLAG_MCA ) {
       if( OT_PEERTIME( peer_dest ) > OT_CLIENT_SYNC_RENEW_BOUNDARY ||
          ( !(OT_PEERFLAG(peer_dest) & PEER_FLAG_COMPLETED ) && (OT_PEERFLAG(peer) & PEER_FLAG_COMPLETED ) ) )
         livesync_tell( hash, peer );
     }
 #endif
-    
+
     if(  (OT_PEERFLAG(peer_dest) & PEER_FLAG_SEEDING )   && !(OT_PEERFLAG(peer) & PEER_FLAG_SEEDING ) )
       torrent->peer_list->seed_count--;
     if( !(OT_PEERFLAG(peer_dest) & PEER_FLAG_SEEDING )   &&  (OT_PEERFLAG(peer) & PEER_FLAG_SEEDING ) )
@@ -141,14 +146,15 @@ ot_torrent *add_peer_to_torrent( ot_hash *hash, ot_peer *peer  WANT_SYNC_PARAM(
 
   *(uint64_t*)(peer_dest) = *(uint64_t*)(peer);
 #ifdef WANT_SYNC
-  /* In order to avoid an unlock/lock between add_peers and return_peers,
-     we only unlock the bucket if return_peers won't do the job: either
-     if we return NULL or if no reply is expected, i.e. when called
-     from livesync code. */
-  if( from_sync )
-    mutex_bucket_unlock_by_hash( hash );
+  if( proto == FLAG_MCA ) {
+    mutex_bucket_unlock_by_hash( hash, delta_torrentcount );
+    return 0;
+  }
 #endif
-  return torrent;
+
+  reply_size = return_peers_for_torrent( torrent, amount, reply, proto );
+  mutex_bucket_unlock_by_hash( &torrent->hash, delta_torrentcount );
+  return reply_size;
 }
 
 static size_t return_peers_all( ot_peerlist *peer_list, char *reply ) {
@@ -186,7 +192,7 @@ static size_t return_peers_selection( ot_peerlist *peer_list, size_t amount, cha
     num_buckets = bucket_list->size;
     bucket_list = (ot_vector *)bucket_list->data;
   }
-    
+
   /* Make fixpoint arithmetic as exact as possible */
 #define MAXPRECBIT (1<<(8*sizeof(int)-3))
   while( !(shifted_pc & MAXPRECBIT ) ) { shifted_pc <<= 1; shift++; }
@@ -220,9 +226,6 @@ static size_t return_peers_selection( ot_peerlist *peer_list, size_t amount, cha
 /* Compiles a list of random peers for a torrent
    * reply must have enough space to hold 92+6*amount bytes
    * does not yet check not to return self
-   * the bucket, torrent resides in has been locked by the
-     add_peer call, the ot_torrent * was gathered from, so we
-     have to unlock it here.
 */
 size_t return_peers_for_torrent( ot_torrent *torrent, size_t amount, char *reply, PROTO_FLAG proto ) {
   ot_peerlist *peer_list = torrent->peer_list;
@@ -230,7 +233,7 @@ size_t return_peers_for_torrent( ot_torrent *torrent, size_t amount, char *reply
 
   if( amount > peer_list->peer_count )
     amount = peer_list->peer_count;
-  
+
   if( proto == FLAG_TCP ) {
     int erval = OT_CLIENT_REQUEST_INTERVAL_RANDOM;
     r += sprintf( r, "d8:completei%zde10:downloadedi%zde10:incompletei%zde8:intervali%ie12:min intervali%ie5:peers%zd:", peer_list->seed_count, peer_list->down_count, peer_list->peer_count-peer_list->seed_count, erval, erval/2, 6*amount );
@@ -251,13 +254,12 @@ size_t return_peers_for_torrent( ot_torrent *torrent, size_t amount, char *reply
   if( proto == FLAG_TCP )
     *r++ = 'e';
 
-  mutex_bucket_unlock_by_hash( &torrent->hash );
   return r - reply;
 }
 
 /* Fetches scrape info for a specific torrent */
 size_t return_udp_scrape_for_torrent( ot_hash *hash, char *reply ) {
-  int          exactmatch;
+  int          exactmatch, delta_torrentcount = 0;
   ot_vector   *torrents_list = mutex_bucket_lock_by_hash( hash );
   ot_torrent  *torrent = binary_search( hash, torrents_list->data, torrents_list->size, sizeof( ot_torrent ), OT_HASH_COMPARE_SIZE, &exactmatch );
 
@@ -269,20 +271,22 @@ size_t return_udp_scrape_for_torrent( ot_hash *hash, char *reply ) {
     if( clean_single_torrent( torrent ) ) {
       vector_remove_torrent( torrents_list, torrent );
       memset( reply, 0, 12);
+      delta_torrentcount = -1;
     } else {
       r[0] = htonl( torrent->peer_list->seed_count );
       r[1] = htonl( torrent->peer_list->down_count );
       r[2] = htonl( torrent->peer_list->peer_count-torrent->peer_list->seed_count );
     }
   }
-  mutex_bucket_unlock_by_hash( hash );
+  mutex_bucket_unlock_by_hash( hash, 0 );
   return 12;
 }
 
 /* Fetches scrape info for a specific torrent */
 size_t return_tcp_scrape_for_torrent( ot_hash *hash_list, int amount, char *reply ) {
-  char        *r = reply;
-  int          exactmatch, i;
+  char *r = reply;
+  int   exactmatch, i;
+  int   delta_torrentcount = 0;
 
   r += sprintf( r, "d5:filesd" );
 
@@ -294,6 +298,7 @@ size_t return_tcp_scrape_for_torrent( ot_hash *hash_list, int amount, char *repl
     if( exactmatch ) {
       if( clean_single_torrent( torrent ) ) {
         vector_remove_torrent( torrents_list, torrent );
+        delta_torrentcount = -1;
       } else {
         int j;
         *r++='2';*r++='0';*r++=':';
@@ -302,7 +307,7 @@ size_t return_tcp_scrape_for_torrent( ot_hash *hash_list, int amount, char *repl
           torrent->peer_list->seed_count, torrent->peer_list->down_count, torrent->peer_list->peer_count-torrent->peer_list->seed_count );
       }
     }
-    mutex_bucket_unlock_by_hash( hash );
+    mutex_bucket_unlock_by_hash( hash, delta_torrentcount );
   }
 
   *r++ = 'e'; *r++ = 'e';
@@ -337,7 +342,7 @@ size_t remove_peer_from_torrent( ot_hash *hash, ot_peer *peer, char *reply, PROT
     int erval = OT_CLIENT_REQUEST_INTERVAL_RANDOM;
     reply_size = sprintf( reply, "d8:completei%zde10:incompletei%zde8:intervali%ie12:min intervali%ie5:peers0:e", peer_list->seed_count, peer_list->peer_count - peer_list->seed_count, erval, erval / 2 );
   }
-  
+
   /* Handle UDP reply */
   if( proto == FLAG_UDP ) {
     ((uint32_t*)reply)[2] = htonl( OT_CLIENT_REQUEST_INTERVAL_RANDOM );
@@ -346,7 +351,7 @@ size_t remove_peer_from_torrent( ot_hash *hash, ot_peer *peer, char *reply, PROT
     reply_size = 20;
   }
 
-  mutex_bucket_unlock_by_hash( hash );
+  mutex_bucket_unlock_by_hash( hash, 0 );
   return reply_size;
 }
 
@@ -355,12 +360,7 @@ void exerr( char * message ) {
   exit( 111 );
 }
 
-int trackerlogic_init( const char * const serverdir ) {
-  if( serverdir && chdir( serverdir ) ) {
-    fprintf( stderr, "Could not chdir() to %s, because %s\n", serverdir, strerror(errno) );
-    return -1;
-  }
-
+void trackerlogic_init( ) {
   srandom( time(NULL) );
   g_tracker_id = random();
 
@@ -371,12 +371,10 @@ int trackerlogic_init( const char * const serverdir ) {
   accesslist_init( );
   livesync_init( );
   stats_init( );
-
-  return 0;
 }
 
 void trackerlogic_deinit( void ) {
-  int bucket;
+  int bucket, delta_torrentcount = 0;
   size_t j;
 
   /* Free all torrents... */
@@ -386,10 +384,11 @@ void trackerlogic_deinit( void ) {
       for( j=0; j<torrents_list->size; ++j ) {
         ot_torrent *torrent = ((ot_torrent*)(torrents_list->data)) + j;
         free_peerlist( torrent->peer_list );
+        delta_torrentcount -= 1;
       }
       free( torrents_list->data );
     }
-    mutex_bucket_unlock( bucket );
+    mutex_bucket_unlock( bucket, delta_torrentcount );
   }
 
   /* Deinitialise background worker threads */
diff --git a/trackerlogic.h b/trackerlogic.h
index 75e98d2..34cee3b 100644
--- a/trackerlogic.h
+++ b/trackerlogic.h
@@ -73,7 +73,6 @@ static const uint8_t PEER_FLAG_LEECHING  = 0x00;
 #define OT_PEERFLAG(peer)     (((uint8_t*)(peer))[6])
 #define OT_PEERTIME(peer)     (((uint8_t*)(peer))[7])
 
-#define OT_PEER_COMPARE_SIZE ((size_t)6)
 #define OT_HASH_COMPARE_SIZE (sizeof(ot_hash))
 
 struct ot_peerlist;
@@ -111,17 +110,17 @@ struct ot_peerlist {
 #define WANT_SYNC_PARAM( param )
 #endif
 
-int  trackerlogic_init( const char * const serverdir );
+void trackerlogic_init( );
 void trackerlogic_deinit( void );
 void exerr( char * message );
 
 /* add_peer_to_torrent does only release the torrent bucket if from_sync is set,
    otherwise it is released in return_peers_for_torrent */
-size_t return_peers_for_torrent( ot_torrent *torrent, size_t amount, char *reply, PROTO_FLAG proto );
-ot_torrent *add_peer_to_torrent( ot_hash *hash, ot_peer *peer  WANT_SYNC_PARAM( int from_sync ) );
-size_t remove_peer_from_torrent( ot_hash *hash, ot_peer *peer, char *reply, PROTO_FLAG proto );
-size_t return_tcp_scrape_for_torrent( ot_hash *hash, int amount, char *reply );
-size_t return_udp_scrape_for_torrent( ot_hash *hash, char *reply );
+#define add_peer_to_torrent(hash,peer,proto) add_peer_to_torrent_and_return_peers(hash,peer,proto,0,NULL)
+size_t  add_peer_to_torrent_and_return_peers( ot_hash *hash, ot_peer *peer, PROTO_FLAG proto, size_t amount, char * reply );
+size_t  remove_peer_from_torrent( ot_hash *hash, ot_peer *peer, char *reply, PROTO_FLAG proto );
+size_t  return_tcp_scrape_for_torrent( ot_hash *hash, int amount, char *reply );
+size_t  return_udp_scrape_for_torrent( ot_hash *hash, char *reply );
 
 /* Helper, before it moves to its own object */
 void free_peerlist( ot_peerlist *peer_list );