added control for suspicious message activity in chat lobbies. Lobby items are not bounced if coming from a peer that sends more messages per seconds than a given limit. The limit is adaptive and depends on lobby count

git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@6751 b45a01b8-16f6-495d-af2f-9b41ad6348cc

libretroshare/src/services/p3chatservice.cc

@@ -23,6 +23,7 @@
  *
  */
 #include <math.h>
+#include <sstream>
 
 #include "openssl/rand.h"
 #include "pgp/rscertificate.h"
@@ -71,6 +72,8 @@ static const uint32_t MAX_AVATAR_JPEG_SIZE              = 32767; // Maximum size
                                                                  // don't transfer correctly and can kill the system.
 																					  // Images are 96x96, which makes approx. 27000 bytes uncompressed.
 static const uint32_t MAX_ALLOWED_LOBBIES_IN_LIST_WARNING = 50 ;
+static const uint32_t MAX_MESSAGES_PER_SECONDS_NUMBER     =  5 ; // max number of messages from a given peer in a window for duration below
+static const uint32_t MAX_MESSAGES_PER_SECONDS_PERIOD     = 10 ; // duration window for max number of messages before messages get dropped.
 
 p3ChatService::p3ChatService(p3LinkMgr *lm, p3HistoryMgr *historyMgr)
 	:p3Service(RS_SERVICE_TYPE_CHAT), p3Config(CONFIG_TYPE_CHAT), mChatMtx("p3ChatService"), mLinkMgr(lm) , mHistoryMgr(historyMgr)
@@ -698,12 +701,71 @@ void p3ChatService::receiveChatQueue()
 	while(NULL != (item=recvItem()))
 		handleIncomingItem(item) ;
 }
+class MsgCounter
+{
+	public:
+		MsgCounter() {}
+
+		void clean(time_t max_time)
+		{
+			while(!recv_times.empty() && recv_times.front() < max_time)
+				recv_times.pop_front() ;
+		}
+		std::list<time_t> recv_times ;
+};
+
+
+bool p3ChatService::locked_bouncingObjectCheck(RsChatLobbyBouncingObject *obj,const std::string& peer_id,uint32_t lobby_count)
+{
+	static std::map<std::string, std::list<time_t> > message_counts ;
+
+	std::ostringstream os ;
+	os << obj->lobby_id ;
+
+	std::string pid = peer_id + "_" + os.str() ;
+
+	VisibleChatLobbyRecord& rec(_visible_lobbies[obj->lobby_id]) ;
+	lobby_count = rec.total_number_of_peers ;
+
+	// max objects per second: lobby_count * 1/MAX_DELAY_BETWEEN_LOBBY_KEEP_ALIVE objects per second.
+	// So in cache, there is in average that number times MAX_MESSAGES_PER_SECONDS_PERIOD
+	//
+	float max_cnt = std::max(10.0f, 4*lobby_count / (float)MAX_DELAY_BETWEEN_LOBBY_KEEP_ALIVE * MAX_MESSAGES_PER_SECONDS_PERIOD) ;
+
+#ifdef CHAT_DEBUG
+	std::cerr << "lobby_count=" << lobby_count << std::endl;
+	std::cerr << "Got msg for peer " << pid << std::dec << ". Limit is " << max_cnt << ". List is " ;
+	for(std::list<time_t>::const_iterator it(message_counts[pid].begin());it!=message_counts[pid].end();++it)
+		std::cerr << *it << " " ;
+	std::cerr << std::endl;
+#endif
+
+	time_t now = time(NULL) ;
+
+	std::list<time_t>& lst = message_counts[pid] ;
+	
+	// Clean old messages time stamps from the list.
+	//
+	while(!lst.empty() && lst.front() + MAX_MESSAGES_PER_SECONDS_PERIOD < now)
+		lst.pop_front() ;
+
+	if(lst.size() > max_cnt)
+	{
+		std::cerr << "Too many messages from peer " << pid << ". Someone (name=" << obj->nick << ") is trying to flood this lobby. Message will not be forwarded." << std::endl;
+		return false;
+	}
+	else
+		lst.push_back(now) ;
+
+	return true ;
+}
 
 void p3ChatService::handleIncomingItem(RsItem *item)
 {
 #ifdef CHAT_DEBUG
 	std::cerr << "p3ChatService::receiveChatQueue() Item:" << (void*)item << std::endl ;
 #endif
+
 	// RsChatMsgItems needs dynamic_cast, since they have derived siblings.
 	//
 	RsChatMsgItem *ci = dynamic_cast<RsChatMsgItem*>(item) ; 
@@ -2139,6 +2201,7 @@ bool p3ChatService::bounceLobbyObject(RsChatLobbyBouncingObject *item,const std:
 #endif
 		return false ;
 	}
+
 	ChatLobbyEntry& lobby(it->second) ;
 
 	// Adds the peer id to the list of friend participants, even if it's not original msg source
@@ -2167,6 +2230,10 @@ bool p3ChatService::bounceLobbyObject(RsChatLobbyBouncingObject *item,const std:
 	lobby.msg_cache[item->msg_id] = now ;
 	lobby.last_activity = now ;
 
+	// Check that if we have a lobby bouncing object, it's not flooding the lobby
+	if(!locked_bouncingObjectCheck(item,peer_id,lobby.participating_friends.size()))
+		return false;
+
 	bool is_message =  (NULL != dynamic_cast<RsChatLobbyMsgItem*>(item)) ;
 
 	// Forward to allparticipating friends, except this peer.

libretroshare/src/services/p3chatservice.h

@@ -230,6 +230,9 @@ class p3ChatService: public p3Service, public p3Config, public pqiMonitor, publi
 		void handleRecvChatLobbyList(RsChatLobbyListItem_deprecated2 *item) ;
 		void handleRecvChatLobbyEventItem(RsChatLobbyEventItem *item) ;
 
+		/// Checks that the lobby object is not flooding a lobby.
+		bool locked_bouncingObjectCheck(RsChatLobbyBouncingObject *obj,const std::string& peer_id,uint32_t lobby_count) ;
+
 		/// Sends a request for an avatar to the peer of given id
 		void sendAvatarRequest(const std::string& peer_id) ;