flood to 2 next day closest floodfills before UTC midnight

libi2pd/Identity.cpp

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2013-2023, The PurpleI2P Project
+* Copyright (c) 2013-2024, The PurpleI2P Project
 *
 * This file is part of Purple i2pd project and licensed under BSD3
 *
@@ -790,11 +790,14 @@ namespace data
 		return keys;
 	}
 
-	IdentHash CreateRoutingKey (const IdentHash& ident)
+	IdentHash CreateRoutingKey (const IdentHash& ident, bool nextDay)
 	{
 		uint8_t buf[41]; // ident + yyyymmdd
 		memcpy (buf, (const uint8_t *)ident, 32);
-		i2p::util::GetCurrentDate ((char *)(buf + 32));
+		if (nextDay)
+			i2p::util::GetNextDayDate ((char *)(buf + 32));
+		else	
+			i2p::util::GetCurrentDate ((char *)(buf + 32));
 		IdentHash key;
 		SHA256(buf, 40, key);
 		return key;

libi2pd/Identity.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2013-2023, The PurpleI2P Project
+* Copyright (c) 2013-2024, The PurpleI2P Project
 *
 * This file is part of Purple i2pd project and licensed under BSD3
 *
@@ -206,7 +206,7 @@ namespace data
 		bool operator< (const XORMetric& other) const { return memcmp (metric, other.metric, 32) < 0; };
 	};
 
-	IdentHash CreateRoutingKey (const IdentHash& ident);
+	IdentHash CreateRoutingKey (const IdentHash& ident, bool nextDay = false);
 	XORMetric operator^(const IdentHash& key1, const IdentHash& key2);
 
 	// destination for delivery instructions

libi2pd/NetDb.cpp

@@ -912,7 +912,10 @@ namespace data
 			{
 				memcpy (payload + DATABASE_STORE_HEADER_SIZE, buf + payloadOffset, msgLen);
 				floodMsg->FillI2NPMessageHeader (eI2NPDatabaseStore);
-				Flood (ident, floodMsg);
+				int minutesBeforeMidnight = 24*60 - i2p::util::GetMinutesSinceEpoch () % (24*60);
+				bool andNextDay = storeType ? minutesBeforeMidnight < NETDB_NEXT_DAY_LEASESET_THRESHOLD:
+					minutesBeforeMidnight < NETDB_NEXT_DAY_ROUTER_INFO_THRESHOLD;
+				Flood (ident, floodMsg, andNextDay);
 			}
 			else
 				LogPrint (eLogError, "NetDb: Database store message is too long ", floodMsg->len);
@@ -1081,24 +1084,43 @@ namespace data
 		}
 	}
 
-	void NetDb::Flood (const IdentHash& ident, std::shared_ptr<I2NPMessage> floodMsg)
+	void NetDb::Flood (const IdentHash& ident, std::shared_ptr<I2NPMessage> floodMsg, bool andNextDay)
 	{
 		std::unordered_set<IdentHash> excluded;
 		excluded.insert (i2p::context.GetIdentHash ()); // don't flood to itself
 		excluded.insert (ident); // don't flood back
 		for (int i = 0; i < 3; i++)
 		{
-			auto floodfill = GetClosestFloodfill (ident, excluded);
+			auto floodfill = GetClosestFloodfill (ident, excluded, false); // current day
 			if (floodfill)
 			{
-				auto h = floodfill->GetIdentHash();
-				LogPrint(eLogDebug, "NetDb: Flood lease set for ", ident.ToBase32(), " to ", h.ToBase64());
+				const auto& h = floodfill->GetIdentHash();
 				transports.SendMessage (h, CopyI2NPMessage(floodMsg));
 				excluded.insert (h);
 			}
 			else
-				break;
+				return; // no more floodfills
 		}
+		if (andNextDay)
+		{
+			// flood to two more closest flodfills for next day 
+			std::unordered_set<IdentHash> excluded1;
+			excluded1.insert (i2p::context.GetIdentHash ()); // don't flood to itself
+			excluded1.insert (ident); // don't flood back
+			for (int i = 0; i < 2; i++)
+			{
+				auto floodfill = GetClosestFloodfill (ident, excluded1, true); // next day
+				if (floodfill)
+				{
+					const auto& h = floodfill->GetIdentHash();
+					if (!excluded.count (h)) // we didn't send for current day, otherwise skip
+						transports.SendMessage (h, CopyI2NPMessage(floodMsg));
+					excluded1.insert (h);
+				}
+				else
+					return;
+			}	
+		}	
 	}
 
 	std::shared_ptr<const RouterInfo> NetDb::GetRandomRouter () const
@@ -1236,9 +1258,9 @@ namespace data
 	}	
 	
 	std::shared_ptr<const RouterInfo> NetDb::GetClosestFloodfill (const IdentHash& destination,
-		const std::unordered_set<IdentHash>& excluded) const
+		const std::unordered_set<IdentHash>& excluded, bool nextDay) const
 	{
-		IdentHash destKey = CreateRoutingKey (destination);
+		IdentHash destKey = CreateRoutingKey (destination, nextDay);
 		std::lock_guard<std::mutex> l(m_FloodfillsMutex);
 		return m_Floodfills.FindClosest (destKey, [&excluded](const std::shared_ptr<RouterInfo>& r)->bool
 			{

libi2pd/NetDb.hpp

@@ -54,6 +54,8 @@ namespace data
 	const size_t NETDB_MAX_NUM_SEARCH_REPLY_PEER_HASHES = 16;
 	const size_t NETDB_MAX_EXPLORATORY_SELECTION_SIZE = 500;
 	const int NETDB_EXPLORATORY_SELECTION_UPDATE_INTERVAL = 82; // in seconds. for floodfill
+	const int NETDB_NEXT_DAY_ROUTER_INFO_THRESHOLD = 45; // in minutes
+	const int NETDB_NEXT_DAY_LEASESET_THRESHOLD = 10; // in minutes
 
 	/** function for visiting a leaseset stored in a floodfill */
 	typedef std::function<void(const IdentHash, std::shared_ptr<LeaseSet>)> LeaseSetVisitor;
@@ -89,7 +91,7 @@ namespace data
 			std::shared_ptr<const RouterInfo> GetHighBandwidthRandomRouter (std::shared_ptr<const RouterInfo> compatibleWith, bool reverse, bool endpoint) const;
 			std::shared_ptr<const RouterInfo> GetRandomSSU2PeerTestRouter (bool v4, const std::unordered_set<IdentHash>& excluded) const;
 			std::shared_ptr<const RouterInfo> GetRandomSSU2Introducer (bool v4, const std::unordered_set<IdentHash>& excluded) const;
-			std::shared_ptr<const RouterInfo> GetClosestFloodfill (const IdentHash& destination, const std::unordered_set<IdentHash>& excluded) const;
+			std::shared_ptr<const RouterInfo> GetClosestFloodfill (const IdentHash& destination, const std::unordered_set<IdentHash>& excluded, bool nextDay = false) const;
 			std::vector<IdentHash> GetClosestFloodfills (const IdentHash& destination, size_t num,
 				std::unordered_set<IdentHash>& excluded, bool closeThanUsOnly = false) const;
 			std::vector<IdentHash> GetExploratoryNonFloodfill (const IdentHash& destination, size_t num, const std::unordered_set<IdentHash>& excluded);
@@ -144,7 +146,7 @@ namespace data
 			void PersistRouters (std::list<std::pair<std::string, std::shared_ptr<RouterInfo::Buffer> > >&& update, 
 				std::list<std::string>&& remove);
 			void Run (); 
-			void Flood (const IdentHash& ident, std::shared_ptr<I2NPMessage> floodMsg);
+			void Flood (const IdentHash& ident, std::shared_ptr<I2NPMessage> floodMsg, bool andNextDay = false);
 			void ManageRouterInfos ();
 			void ManageLeaseSets ();
 			void ManageRequests ();

libi2pd/Timestamp.cpp

@@ -255,6 +255,11 @@ namespace util
 		GetDateString (GetSecondsSinceEpoch (), date);
 	}
 
+	void GetNextDayDate (char * date)
+	{
+		GetDateString (GetSecondsSinceEpoch () + 24*60*60, date);
+	}	
+	
 	void GetDateString (uint64_t timestamp, char * date)
 	{
 		using clock = std::chrono::system_clock;

libi2pd/Timestamp.h

@@ -28,7 +28,8 @@ namespace util
 	uint64_t GetMonotonicMilliseconds ();
 	uint64_t GetMonotonicSeconds ();
 	
-	void GetCurrentDate (char * date); // returns date as YYYYMMDD string, 9 bytes
+	void GetCurrentDate (char * date); // returns UTC date as YYYYMMDD string, 9 bytes
+	void GetNextDayDate (char * date); // returns next UTC day as YYYYMMDD string, 9 bytes
 	void GetDateString (uint64_t timestamp, char * date); // timestamp is seconds since epoch, returns date as YYYYMMDD string, 9 bytes
 	void AdjustTimeOffset (int64_t offset); // in seconds from current