fixed bug related to ignoring upload slots and made the piece rejection code more robust to handle similar bugs better

docs/manual.rst

@@ -3303,6 +3303,8 @@ that will be sent to the tracker. The user-agent is a good way to identify your
 		int max_sparse_regions;
 
 		bool lock_disk_cache;
+
+		int max_rejects;
 	};
 
 ``user_agent`` this is the client identification to the tracker.
@@ -3638,6 +3640,11 @@ to 0 on all platforms except windows.
 that's in use, will be locked in physical memory, preventing it from
 being swapped out.
 
+``max_rejects`` is the number of piece requests we will reject in a row
+while a peer is choked before the peer is considered abusive and is
+disconnected.
+
+
 pe_settings
 ===========
 

include/libtorrent/peer_connection.hpp

@@ -820,6 +820,14 @@ namespace libtorrent
 		// at the remote end.
 		boost::uint8_t m_desired_queue_size;
 
+		// the number of piece requests we have rejected
+		// in a row because the peer is choked. This is
+		// used to re-send the choked message in case the
+		// other end keeps requesting pieces while being
+		// choked, and eventuelly disconnect if it keeps
+		// requesting too many pieces while being choked
+		boost::uint8_t m_choke_rejects;
+
 		// if this is true, the disconnection
 		// timestamp is not updated when the connection
 		// is closed. This means the time until we can

include/libtorrent/session_settings.hpp

@@ -159,6 +159,7 @@ namespace libtorrent
 #ifndef TORRENT_DISABLE_MLOCK
 			, lock_disk_cache(true)
 #endif
+			, max_rejects(50)
 		{}
 
 		// this is the user agent that will be sent to the tracker
@@ -523,6 +524,10 @@ namespace libtorrent
 		// be swapped out
 		bool lock_disk_cache;
 #endif
+
+		// the number of times to reject requests while being
+		// choked before disconnecting a peer for being malicious
+		int max_rejects;
 	};
 
 #ifndef TORRENT_DISABLE_DHT

src/peer_connection.cpp

@@ -117,6 +117,7 @@ namespace libtorrent
 		, m_rtt(0)
 		, m_prefer_whole_pieces(0)
 		, m_desired_queue_size(2)
+		, m_choke_rejects(0)
 		, m_fast_reconnect(false)
 		, m_active(true)
 		, m_peer_interested(false)
@@ -228,6 +229,7 @@ namespace libtorrent
 		, m_rtt(0)
 		, m_prefer_whole_pieces(0)
 		, m_desired_queue_size(2)
+		, m_choke_rejects(0)
 		, m_fast_reconnect(false)
 		, m_active(false)
 		, m_peer_interested(false)
@@ -1166,7 +1168,7 @@ namespace libtorrent
 #endif
 		m_peer_interested = true;
 		if (is_disconnecting()) return;
-		if (ignore_unchoke_slots()) write_unchoke();
+		if (ignore_unchoke_slots()) send_unchoke();
 		t->get_policy().interested(*this);
 	}
 
@@ -1209,7 +1211,7 @@ namespace libtorrent
 			m_ses.m_unchoke_time_scaler = 0;
 		}
 
-		if (ignore_unchoke_slots()) write_choke();
+		if (ignore_unchoke_slots()) send_unchoke();
 		t->get_policy().not_interested(*this);
 
 		if (t->super_seeding() && m_superseed_piece != -1)
@@ -1611,6 +1613,7 @@ namespace libtorrent
 			if (m_choked && m_accept_fast.find(r.piece) == m_accept_fast.end())
 			{
 				write_reject_request(r);
+				++m_choke_rejects;
 #if defined TORRENT_VERBOSE_LOGGING || defined TORRENT_ERROR_LOGGING
 				(*m_logger) << time_now_string()
 					<< " *** REJECTING REQUEST [ peer choked and piece not in allowed fast set ]\n";
@@ -1620,9 +1623,22 @@ namespace libtorrent
 					"s: " << r.start << " | "
 					"l: " << r.length << " ]\n";
 #endif
+
+				if (m_choke_rejects > m_ses.settings().max_rejects)
+				{
+					disconnect("too many piece requests while choked");
+					return;
+				}
+				else if ((m_choke_rejects & 0xf) == 0)
+				{
+					// tell the peer it's choked again
+					// every 16 requests in a row
+					write_choke();
+				}
 			}
 			else
 			{
+				m_choke_rejects = 0;
 				m_requests.push_back(r);
 				m_last_incoming_request = time_now();
 				fill_send_buffer();
@@ -2437,6 +2453,7 @@ namespace libtorrent
 		boost::shared_ptr<torrent> t = m_torrent.lock();
 		TORRENT_ASSERT(t);
 
+		if (has_peer_choked()) return;
 		if ((int)m_download_queue.size() >= m_desired_queue_size) return;
 
 		bool empty_download_queue = m_download_queue.empty();

src/policy.cpp

@@ -884,7 +884,7 @@ namespace libtorrent
 			&& ses.num_uploads() < ses.max_uploads()
 			&& !c.ignore_unchoke_slots()
 			&& (m_torrent->ratio() == 0
-				|| c.share_diff() >= -free_upload_amount
+				|| c.share_diff() >= size_type(-free_upload_amount)
 				|| m_torrent->is_finished()))
 		{
 			ses.unchoke_peer(c);