add support to detect when our node is neighbor of a special resource (eg. torrent tracker)

libtorrent/include/libtorrent/kademlia/dht_get.hpp

@@ -64,7 +64,7 @@ public:
 	typedef boost::function<void(entry::list_type const&)> data_callback;
 
 	// callback to receive all write tokens
-	typedef boost::function<void(std::vector<std::pair<node_entry, std::string> > const&, bool)> nodes_callback;
+	typedef boost::function<void(std::vector<std::pair<node_entry, std::string> > const&, bool, node_id)> nodes_callback;
 
 	void got_data(entry::list_type const& values_list);
 	void got_write_token(node_id const& n, std::string const& write_token)

libtorrent/src/kademlia/dht_get.cpp

@@ -269,7 +269,7 @@ void dht_get::done()
 		results.push_back(std::make_pair(node_entry(o->id(), o->target_ep()), j->second));
 		--num_results;
 	}
-	m_nodes_callback(results, m_got_data);
+	m_nodes_callback(results, m_got_data, target());
 
 	traversal_algorithm::done();
 }

libtorrent/src/kademlia/node.cpp

@@ -367,10 +367,22 @@ namespace
 	}
 
 	void getDataDone_fun(std::vector<std::pair<node_entry, std::string> > const& node_results,
-			     bool got_data, node_impl& node,
+			     bool got_data, node_id target, node_impl& node,
 			     boost::function<void(bool, bool)> fdone)
 	{
 	    bool is_neighbor = false;
+
+	    // check distance between target, nodes and our own id
+	    // n is sorted from closer(begin) to more distant (back)
+	    if( node_results.size() < node.m_table.bucket_size() ) {
+		    is_neighbor = true;
+	    } else {
+		    node_id dFarther = distance(node_results.back().first.id, target);
+		    node_id dOwn     = distance(node.nid(), target);
+		    if( dOwn < dFarther )
+			    is_neighbor = true;
+	    }
+
 	    fdone(is_neighbor, got_data);
 	}
 }
@@ -449,7 +461,7 @@ void node_impl::getData(std::string const &username, std::string const &resource
 	// for info-hash id. callback is used to return data.
 	boost::intrusive_ptr<dht_get> ta(new dht_get(*this, username, resource, multi,
 		 fdata,
-		 boost::bind(&getDataDone_fun, _1, _2, boost::ref(*this), fdone), false));
+		 boost::bind(&getDataDone_fun, _1, _2, _3, boost::ref(*this), fdone), false));
 	ta->start();
 }
 

src/twister.cpp

@@ -31,7 +31,7 @@ static session *ses = NULL;
 
 static CCriticalSection cs_dhtgetMap;
 static map<uint256, alert_manager*> m_dhtgetMap;
-
+static map<std::string, bool> m_specialResources;
 
 uint256 dhtTargetHash(std::string const &username, std::string const &resource, std::string const &type)
 {
@@ -281,11 +281,14 @@ void ThreadSessionAlerts()
                             r && r->type() == entry::string_t &&
                             t && t->type() == entry::string_t) {
 
+                            // if this is a special resource then start another dhtget to make
+                            // sure we are really its neighbor. don't do it needless.
+                            if( m_specialResources.count(r->string()) ) {
                                 // now we do our own search to make sure we are really close to this target
                                 uint256 th = dhtTargetHash(n->string(), r->string(), t->string());
 
                                 if( !neighborCheck.count(th) ) {
-                                printf("possiblyNeighbor of [%s,%s,%s]\n",
+                                    printf("possiblyNeighbor of [%s,%s,%s] - starting a new dhtget to be sure\n",
                                            n->string().c_str(),
                                            r->string().c_str(),
                                            t->string().c_str());
@@ -294,6 +297,7 @@ void ThreadSessionAlerts()
                                     ses->dht_getData(n->string(), r->string(), t->string() == "m");
                                 }
                             }
+                        }
 
                     }
                     continue;
@@ -318,6 +322,10 @@ void ThreadSessionAlerts()
                         }
                     }
 
+                    if( dd->m_is_neighbor && m_specialResources.count(dd->m_resource) ) {
+                        // Do something!
+                        printf("Neighbor of special resource - do something!\n");
+                    }
                     continue;
                 }
 
@@ -342,6 +350,8 @@ void startSessionTorrent(boost::thread_group& threadGroup)
 {
     printf("startSessionTorrent (waiting for external IP)\n");
 
+    m_specialResources["tracker"] = true;
+
     threadGroup.create_thread(boost::bind(&ThreadWaitExtIP));
     threadGroup.create_thread(boost::bind(&ThreadMaintainDHTNodes));
     threadGroup.create_thread(boost::bind(&ThreadSessionAlerts));