If bitcoin network goes down, pause libtorrent to prevent pieces being falsely rejected because height > bestHeight.

Also, if bitcoin network is down, try to add nodes from DHT bucket tables back to the bitcoin network.

libtorrent/include/libtorrent/session_status.hpp

@@ -35,6 +35,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #include "libtorrent/config.hpp"
 #include "libtorrent/size_type.hpp"
+#include "libtorrent/union_endpoint.hpp"
 #include <vector>
 
 namespace libtorrent
@@ -66,6 +67,7 @@ namespace libtorrent
 		int num_replacements;
 		// number of seconds since last activity
 		int last_active;
+		union_endpoint random_node;
 	};
 
 	struct utp_status

libtorrent/src/kademlia/routing_table.cpp

@@ -91,6 +91,10 @@ void routing_table::status(session_status& s) const
 		b.num_nodes = i->live_nodes.size();
 		b.num_replacements = i->replacements.size();
 		b.last_active = total_seconds(now - i->last_active);
+		if( b.num_nodes ) {
+			int randNode = rand() % b.num_nodes;
+			b.random_node = i->live_nodes[randNode].endpoint;
+		}
 		s.dht_routing_table.push_back(b);
 	}
 }

src/twister.cpp

@@ -182,11 +182,6 @@ void ThreadWaitExtIP()
         MilliSleep(500);
     }
 
-    // delay libtorrent initialization until we have valid blocks
-    while( getBestHeight() <= 0 ) {
-        MilliSleep(500);
-    }
-
     error_code ec;
     int listen_port = GetListenPort() + LIBTORRENT_PORT_OFFSET;
     std::string bind_to_interface = "";
@@ -199,6 +194,9 @@ void ThreadWaitExtIP()
             , ipStr.size() ? ipStr.c_str() : NULL
             , std::make_pair(listen_port, listen_port));
 
+    // session will be paused until we have an up-to-date blockchain
+    ses->pause();
+
     std::vector<char> in;
     boost::filesystem::path sesStatePath = GetDataDir() / "ses_state";
     if (load_file(sesStatePath.string(), in) == 0)
@@ -275,6 +273,12 @@ void ThreadWaitExtIP()
     }
 }
 
+bool isBlockChainUptodate() {
+    if( !pindexBest )
+        return false;
+    return (pindexBest->GetBlockTime() > GetTime() - 1 * 60 * 60);
+}
+
 void ThreadMaintainDHTNodes()
 {
     RenameThread("maintain-dht-nodes");
@@ -284,16 +288,16 @@ void ThreadMaintainDHTNodes()
     }
 
     while(1) {
-        MilliSleep(5000);
-
         session_status ss = ses->status();
         int dht_nodes = ss.dht_nodes;
         bool nodesAdded = false;
+        int vNodesSize = 0;
 
         if( ses ) {
             LOCK(cs_vNodes);
+            vNodesSize = vNodes.size();
             vector<CAddress> vAddr = addrman.GetAddr();
-            int totalNodesCandidates = (int)(vNodes.size() + vAddr.size());
+            int totalNodesCandidates = (int)(vNodesSize + vAddr.size());
             if( (!dht_nodes && totalNodesCandidates) ||
                 (dht_nodes < 5 && totalNodesCandidates > 10) ) {
                 printf("ThreadMaintainDHTNodes: too few dht_nodes, trying to add some...\n");
@@ -321,8 +325,21 @@ void ThreadMaintainDHTNodes()
                 }
             }
         }
+
+        if( ses->is_paused() ) {
+            if( vNodesSize && isBlockChainUptodate() ) {
+                printf("BlockChain is now up-to-date: unpausing libtorrent session\n");
+                ses->resume();
+            }
+        } else {
+            if( !vNodesSize || !isBlockChainUptodate() ) {
+                printf("Outdated BlockChain detected: pausing libtorrent session\n");
+                ses->pause();
+            }
+        }
+
         if( nodesAdded ) {
-            MilliSleep(5000);
+            MilliSleep(2000);
             ss = ses->status();
             if( ss.dht_nodes > dht_nodes ) {
                 // new nodes were added to dht: force updating peers from dht so torrents may start faster
@@ -330,12 +347,27 @@ void ThreadMaintainDHTNodes()
                 BOOST_FOREACH(const PAIRTYPE(std::string, torrent_handle)& item, m_userTorrent) {
                     item.second.force_dht_announce();
                 }
-            } else {
-                // nodes added but dht ignored them, so they are probably duplicated.
-                // we sleep a bit as a punishment :-)
-                MilliSleep(30000);
             }
         }
+
+        if( !vNodesSize && dht_nodes ) {
+            printf("ThreadMaintainDHTNodes: registration network is down, trying to add nodes from DHT...\n");
+            for( size_t i = 0; i < ss.dht_routing_table.size(); i++ ) {
+                dht_routing_bucket &bucket = ss.dht_routing_table[i];
+                if( bucket.num_nodes ) {
+                    printf("DHT bucket [%zd] random node = %s:%d\n", i,
+                           bucket.random_node.address().to_string().c_str(),
+                           bucket.random_node.port);
+                    char nodeStr[64];
+                    sprintf(nodeStr,"%s:%d", bucket.random_node.address().to_string().c_str(),
+                            bucket.random_node.port - LIBTORRENT_PORT_OFFSET);
+                    CAddress addr;
+                    ConnectNode(addr, nodeStr);
+                }
+            }
+        }
+
+        MilliSleep(5000);
     }
 }