reorder the node-list in the DHT traversal algorithm if a node updates its ID

include/libtorrent/kademlia/observer.hpp

@@ -115,7 +115,7 @@ struct observer : boost::noncopyable
 	address target_addr() const;
 	udp::endpoint target_ep() const;
 
-	void set_id(node_id const& id) { m_id = id; }
+	void set_id(node_id const& id);
 	node_id const& id() const { return m_id; }
 
 	void set_transaction_id(boost::uint16_t tid)

include/libtorrent/kademlia/traversal_algorithm.hpp

@@ -77,6 +77,7 @@ struct traversal_algorithm : boost::noncopyable
 
 	node_id const& target() const { return m_target; }
 
+	void resort_results();
 	void add_entry(node_id const& id, udp::endpoint addr, unsigned char flags);
 
 	traversal_algorithm(node_impl& node, node_id target);

src/kademlia/find_data.cpp

@@ -80,10 +80,6 @@ void find_data_observer::reply(msg const& m)
 			node_id(id->string_ptr()), token->string_value());
 	}
 
-	// in case we didn't know the id of this peer when we sent the message to
-	// it. For instance if it's a bootstrap node.
-	set_id(node_id(id->string_ptr()));
-
 	traversal_observer::reply(m);
 	done();
 }

src/kademlia/rpc_manager.cpp

@@ -151,6 +151,13 @@ void observer::timeout()
 	m_algorithm->failed(observer_ptr(this));
 }
 
+void observer::set_id(node_id const& id)
+{
+	if (m_id == id) return;
+	m_id = id;
+	if (m_algorithm) m_algorithm->resort_results();
+}
+
 enum { observer_size = max3<
 	sizeof(find_data_observer)
 	, sizeof(announce_observer)

src/kademlia/traversal_algorithm.cpp

@@ -42,6 +42,10 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/broadcast_socket.hpp" // for cidr_distance
 #include <libtorrent/socket_io.hpp> // for read_*_endpoint
 
+#if TORRENT_USE_ASSERTS
+#include <boost/algorithm/cxx11/is_sorted.hpp> // for is_sorted
+#endif
+
 #include <boost/bind.hpp>
 
 namespace libtorrent { namespace dht
@@ -100,6 +104,20 @@ bool compare_ip_cidr(observer_ptr const& lhs, observer_ptr const& rhs)
 	return dist <= cutoff;
 }
 
+void traversal_algorithm::resort_results()
+{
+	std::sort(
+		m_results.begin()
+		, m_results.end()
+		, boost::bind(
+			compare_ref
+			, boost::bind(&observer::id, _1)
+			, boost::bind(&observer::id, _2)
+			, m_target
+		)
+	);
+}
+
 void traversal_algorithm::add_entry(node_id const& id, udp::endpoint addr, unsigned char flags)
 {
 	TORRENT_ASSERT(m_node.m_rpc.allocation_size() >= sizeof(find_data_observer));
@@ -121,6 +139,14 @@ void traversal_algorithm::add_entry(node_id const& id, udp::endpoint addr, unsig
 
 	o->flags |= flags;
 
+	TORRENT_ASSERT(boost::algorithm::is_sorted(m_results.begin(), m_results.end()
+		, boost::bind(
+			compare_ref
+			, boost::bind(&observer::id, _1)
+			, boost::bind(&observer::id, _2)
+			, m_target)
+		));
+
 	std::vector<observer_ptr>::iterator i = std::lower_bound(
 		m_results.begin()
 		, m_results.end()
@@ -172,6 +198,14 @@ void traversal_algorithm::add_entry(node_id const& id, udp::endpoint addr, unsig
 			;
 #endif
 		i = m_results.insert(i, o);
+
+		TORRENT_ASSERT(boost::algorithm::is_sorted(m_results.begin(), m_results.end()
+			, boost::bind(
+				compare_ref
+				, boost::bind(&observer::id, _1)
+				, boost::bind(&observer::id, _2)
+				, m_target)
+			));
 	}
 
 	if (m_results.size() > 100)
@@ -512,6 +546,19 @@ void traversal_observer::reply(msg const& m)
 			m_algorithm->traverse(id, read_v4_endpoint<udp::endpoint>(nodes));
 		}
 	}
+
+	lazy_entry const* id = r->dict_find_string("id");
+	if (!id || id->string_length() != 20)
+	{
+#ifdef TORRENT_DHT_VERBOSE_LOGGING
+		TORRENT_LOG(traversal) << "[" << m_algorithm.get() << "] invalid id in response";
+#endif
+		return;
+	}
+
+	// in case we didn't know the id of this peer when we sent the message to
+	// it. For instance if it's a bootstrap node.
+	set_id(node_id(id->string_ptr()));
 }
 
 void traversal_algorithm::abort()