added consistent detection of time-shift in chat lobbies. Shows a warning when the shift is larger than 2^9 seconds (approx. 10 minutes. Warning shown only once).

git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@6242 b45a01b8-16f6-495d-af2f-9b41ad6348cc

libretroshare/src/retroshare/rsiface.h

@@ -185,6 +185,7 @@ class NotifyBase
 	virtual void notifyErrorMsg(int list, int sev, std::string msg) { (void) list; (void) sev; (void) msg; return; }
 	virtual void notifyChatStatus(const std::string& /* peer_id */, const std::string& /* status_string */ ,bool /* is_private */) {}
 	virtual void notifyChatLobbyEvent(uint64_t /* lobby id */,uint32_t /* event type */,const std::string& /* nickname */,const std::string& /* any string */) {}
+	virtual void notifyChatLobbyTimeShift(int time_shift) {}
 	virtual void notifyCustomState(const std::string& /* peer_id */, const std::string& /* status_string */) {}
 	virtual void notifyHashingInfo(uint32_t type, const std::string& fileinfo) { (void) type; (void)fileinfo; }
 	virtual void notifyTurtleSearchResult(uint32_t /* search_id */ ,const std::list<TurtleFileInfo>& files) { (void)files; }

libretroshare/src/services/p3chatservice.cc

@@ -22,6 +22,7 @@
  * Please report all bugs and problems to "retroshare@lunamutt.com".
  *
  */
+#include <math.h>
 
 #include "util/rsdir.h"
 #include "util/rsrandom.h"
@@ -58,6 +59,7 @@ p3ChatService::p3ChatService(p3LinkMgr *lm, p3HistoryMgr *historyMgr)
 
 	_own_avatar = NULL ;
 	_custom_status_string = "" ;
+	_time_shift_average = 0.0f ;
 	_default_nick_name = rsPeers->getPeerName(rsPeers->getOwnId());
 	_should_reset_lobby_counts = false ;
 	
@@ -798,6 +800,62 @@ void p3ChatService::handleRecvChatLobbyList(RsChatLobbyListItem *item)
 	rsicontrol->getNotify().notifyListChange(NOTIFY_LIST_CHAT_LOBBY_LIST, NOTIFY_TYPE_ADD) ;
 	_should_reset_lobby_counts = false ;
 }
+
+void p3ChatService::addTimeShiftStatistics(int D)
+{
+	static const int S = 50 ; // accuracy up to 2^50 second. Quite conservative!
+	static int total = 0 ;
+	static std::vector<int> log_delay_histogram(S,0) ;
+
+	int delay = (D<0)?(-D):D ;
+
+	if(delay < 0)
+		delay = -delay ;
+
+	// compute log2.
+	int l = 0 ;
+	while(delay > 0) delay >>= 1, ++l ;
+
+	int bin = std::min(S-1,l) ;
+	++log_delay_histogram[bin] ;
+	++total ;
+
+#ifdef CHAT_DEBUG
+	std::cerr << "New delay stat item. delay=" << D << ", log=" << bin << " total=" << total << ", histogram = " ;
+
+	for(int i=0;i<S;++i)
+		std::cerr << log_delay_histogram[i] << " " ;
+#endif
+
+	if(total > 30)
+	{
+		float t = 0.0f ;
+		int i=0 ;
+		for(;i<S && t<0.5*total;++i)
+			t += log_delay_histogram[i] ;
+
+		if(i == 0) return ;									// cannot happen, since total>0 so i is incremented
+		if(log_delay_histogram[i-1] == 0) return ;	// cannot happen, either, but let's be cautious.
+
+		float expected = ( i * (log_delay_histogram[i-1] - t + total*0.5) + (i-1) * (t - total*0.5) ) / (float)log_delay_histogram[i-1] - 1;
+
+#ifdef CHAT_DEBUG
+		std::cerr << ". Expected delay: " << expected << std::endl ;
+#endif
+
+		if(expected > 9)	// if more than 20 samples
+			rsicontrol->getNotify().notifyChatLobbyTimeShift( (int)pow(2.0f,expected)) ;
+
+		total = 0.0f ;
+		log_delay_histogram.clear() ;
+		log_delay_histogram.resize(S,0) ;
+	}
+#ifdef CHAT_DEBUG
+	else
+		std::cerr << std::endl;
+#endif
+}
+
 void p3ChatService::handleRecvChatLobbyEventItem(RsChatLobbyEventItem *item)
 {
 #ifdef CHAT_DEBUG
@@ -805,6 +863,8 @@ void p3ChatService::handleRecvChatLobbyEventItem(RsChatLobbyEventItem *item)
 #endif
 	time_t now = time(NULL) ;
 
+	addTimeShiftStatistics((int)now - (int)item->sendTime) ;
+
 	if(now+100 > (time_t) item->sendTime + MAX_KEEP_MSG_RECORD)	// the message is older than the max cache keep minus 100 seconds ! It's too old, and is going to make an echo!
 	{
 		std::cerr << "Received severely outdated lobby event item (" << now - (time_t)item->sendTime << " in the past)! Dropping it!" << std::endl;

libretroshare/src/services/p3chatservice.h

@@ -194,6 +194,8 @@ class p3ChatService: public p3Service, public p3Config, public pqiMonitor
 
 		void initRsChatInfo(RsChatMsgItem *c, ChatInfo &i);
 
+		/// make some statistics about time shifts, to prevent various issues. 
+		void addTimeShiftStatistics(int shift) ;
 
 		/// Send avatar info to peer in jpeg format.
 		void sendAvatarJpegData(const std::string& peer_id) ;
@@ -286,6 +288,7 @@ class p3ChatService: public p3Service, public p3Config, public pqiMonitor
 		std::map<ChatLobbyId,VisibleChatLobbyRecord> _visible_lobbies ;
 		std::map<std::string,ChatLobbyId> _lobby_ids ;
 		std::string _default_nick_name ;
+		float _time_shift_average ;
 		time_t last_lobby_challenge_time ; // prevents bruteforce attack
 		time_t last_visible_lobby_info_request_time ;	// allows to ask for updates
 		bool _should_reset_lobby_counts ;