fixed race codition between RouterInfo's buffer persist and update

libi2pd/NetDb.cpp

@@ -698,7 +698,7 @@ namespace data
 			expirationTimeout = i2p::context.IsFloodfill () ? NETDB_FLOODFILL_EXPIRATION_TIMEOUT*1000LL :
 				NETDB_MIN_EXPIRATION_TIMEOUT*1000LL + (NETDB_MAX_EXPIRATION_TIMEOUT - NETDB_MIN_EXPIRATION_TIMEOUT)*1000LL*NETDB_MIN_ROUTERS/total;
 
-		std::list<std::pair<std::string, std::shared_ptr<RouterInfo> > > saveToDisk;
+		std::list<std::pair<std::string, std::shared_ptr<RouterInfo::Buffer> > > saveToDisk;
 		std::list<std::string> removeFromDisk;	
 			
 		auto own = i2p::context.GetSharedRouterInfo ();
@@ -711,7 +711,14 @@ namespace data
 				if (it.second->GetBuffer ())
 				{
 					// we have something to save
-					saveToDisk.push_back(std::make_pair(ident, it.second));
+					std::shared_ptr<RouterInfo::Buffer> buffer;
+					{
+						std::lock_guard<std::mutex> l(m_RouterInfosMutex); // possible collision between DeleteBuffer and Update
+						buffer = it.second->GetSharedBuffer ();
+						it.second->DeleteBuffer ();
+					}
+					if (buffer && !it.second->IsUnreachable ()) // don't save bad router
+						saveToDisk.push_back(std::make_pair(ident, buffer));
 					it.second->SetUnreachable (false);
 				}
 				it.second->SetUpdated (false);
@@ -800,15 +807,11 @@ namespace data
 		}
 	}
 
-	void NetDb::PersistRouters (std::list<std::pair<std::string, std::shared_ptr<RouterInfo> > >&& update, 
+	void NetDb::PersistRouters (std::list<std::pair<std::string, std::shared_ptr<RouterInfo::Buffer> > >&& update, 
 		std::list<std::string>&& remove)
 	{
 		for (auto it: update)
-		{	
-			it.second->SaveToFile (m_Storage.Path(it.first));
-			std::lock_guard<std::mutex> l(m_RouterInfosMutex); // possible collision between DeleteBuffer and Update
-			it.second->DeleteBuffer ();
-		}	
+			RouterInfo::SaveToFile (m_Storage.Path(it.first), it.second);
 		for (auto it: remove)
 			m_Storage.Remove (it);
 	}	

libi2pd/NetDb.hpp

@@ -146,7 +146,7 @@ namespace data
 			void Load ();
 			bool LoadRouterInfo (const std::string& path, uint64_t ts);
 			void SaveUpdated ();
-			void PersistRouters (std::list<std::pair<std::string, std::shared_ptr<RouterInfo> > >&& update, 
+			void PersistRouters (std::list<std::pair<std::string, std::shared_ptr<RouterInfo::Buffer> > >&& update, 
 				std::list<std::string>&& remove);
 			void Run (); // exploratory thread
 			void Explore (int numDestinations);

libi2pd/RouterInfo.cpp

@@ -34,6 +34,7 @@ namespace data
 	{
 		if (len > size ()) len = size ();
 		memcpy (data (), buf, len);
+		m_BufferLen = len;
 	}
 
 	RouterInfo::RouterInfo (): m_Buffer (nullptr)
@@ -60,7 +61,7 @@ namespace data
 		{
 			m_Addresses = boost::make_shared<Addresses>(); // create empty list
 			m_Buffer = buf;
-			m_BufferLen = len;
+			if (m_Buffer) m_Buffer->SetBufferLen (len);
 			ReadFromBuffer (true);
 		}
 		else
@@ -129,8 +130,8 @@ namespace data
 		if (s.is_open ())
 		{
 			s.seekg (0,std::ios::end);
-			m_BufferLen = s.tellg ();
-			if (m_BufferLen < 40 || m_BufferLen > MAX_RI_BUFFER_SIZE)
+			size_t bufferLen = s.tellg ();
+			if (bufferLen < 40 || bufferLen > MAX_RI_BUFFER_SIZE)
 			{
 				LogPrint(eLogError, "RouterInfo: File ", fullPath, " is malformed");
 				return false;
@@ -138,7 +139,8 @@ namespace data
 			s.seekg(0, std::ios::beg);
 			if (!m_Buffer)
 				m_Buffer = NewBuffer ();
-			s.read((char *)m_Buffer->data (), m_BufferLen);
+			s.read((char *)m_Buffer->data (), bufferLen);
+			m_Buffer->SetBufferLen (bufferLen);
 		}
 		else
 		{
@@ -163,11 +165,12 @@ namespace data
 			m_IsUnreachable = true;
 			return;
 		}
-		m_RouterIdentity = NewIdentity (m_Buffer->data (), m_BufferLen);
+		size_t bufferLen = m_Buffer->GetBufferLen ();
+		m_RouterIdentity = NewIdentity (m_Buffer->data (), bufferLen);
 		size_t identityLen = m_RouterIdentity->GetFullLen ();
-		if (identityLen >= m_BufferLen)
+		if (identityLen >= bufferLen)
 		{
-			LogPrint (eLogError, "RouterInfo: Identity length ", identityLen, " exceeds buffer size ", m_BufferLen);
+			LogPrint (eLogError, "RouterInfo: Identity length ", identityLen, " exceeds buffer size ", bufferLen);
 			m_IsUnreachable = true;
 			return;
 		}
@@ -181,7 +184,7 @@ namespace data
 				return;
 			}
 			// verify signature
-			int l = m_BufferLen - m_RouterIdentity->GetSignatureLen ();
+			int l = bufferLen - m_RouterIdentity->GetSignatureLen ();
 			if (l < 0 || !m_RouterIdentity->Verify ((uint8_t *)m_Buffer->data (), l, (uint8_t *)m_Buffer->data () + l))
 			{
 				LogPrint (eLogError, "RouterInfo: Signature verification failed");
@@ -191,7 +194,7 @@ namespace data
 		}
 		// parse RI
 		std::stringstream str;
-		str.write ((const char *)m_Buffer->data () + identityLen, m_BufferLen - identityLen);
+		str.write ((const char *)m_Buffer->data () + identityLen, bufferLen - identityLen);
 		ReadFromStream (str);
 		if (!str)
 		{
@@ -625,22 +628,28 @@ namespace data
 		return m_Buffer->data ();
 	}
 
-	bool RouterInfo::SaveToFile (const std::string& fullPath)
+	bool RouterInfo::SaveToFile (const std::string& fullPath, std::shared_ptr<Buffer> buf)
 	{
-		if (m_IsUnreachable) return false; // don't save bad router
-		if (!m_Buffer)
-		{
-			LogPrint (eLogWarning, "RouterInfo: Can't save, m_Buffer == NULL");
-			return false;
-		}
+		if (!buf) return false;
 		std::ofstream f (fullPath, std::ofstream::binary | std::ofstream::out);
 		if (!f.is_open ()) 
 		{
 			LogPrint (eLogError, "RouterInfo: Can't save to ", fullPath);
 			return false;
 		}
-		f.write ((char *)m_Buffer->data (), m_BufferLen);
+		f.write ((char *)buf->data (), buf->GetBufferLen ());
 		return true;
+	}	
+		
+	bool RouterInfo::SaveToFile (const std::string& fullPath)
+	{
+		if (m_IsUnreachable) return false; // don't save bad router
+		if (!m_Buffer)
+		{
+			LogPrint (eLogWarning, "RouterInfo: Can't save, m_Buffer == NULL");
+			return false;
+		}
+		return SaveToFile (fullPath, m_Buffer);
 	}
 
 	size_t RouterInfo::ReadString (char * str, size_t len, std::istream& s) const
@@ -1108,7 +1117,7 @@ namespace data
 			m_Buffer = NewBuffer ();
 		if (len > m_Buffer->size ()) len = m_Buffer->size ();
 		memcpy (m_Buffer->data (), buf, len);
-		m_BufferLen = len;
+		m_Buffer->SetBufferLen (len);
 	}
 
 	std::shared_ptr<RouterInfo::Buffer> RouterInfo::NewBuffer () const

libi2pd/RouterInfo.h

@@ -188,6 +188,13 @@ namespace data
 
 					Buffer () = default;
 					Buffer (const uint8_t * buf, size_t len);
+
+					size_t GetBufferLen () const { return m_BufferLen; };
+					void SetBufferLen (size_t len) { m_BufferLen = len; };
+					
+				private:
+
+					size_t m_BufferLen = 0;
 			};
 
 			typedef std::array<std::shared_ptr<Address>, eNumTransports> Addresses;
@@ -272,18 +279,20 @@ namespace data
 
 			const uint8_t * GetBuffer () const { return m_Buffer ? m_Buffer->data () : nullptr; };
 			const uint8_t * LoadBuffer (const std::string& fullPath); // load if necessary
-			size_t GetBufferLen () const { return m_BufferLen; };
+			size_t GetBufferLen () const { return m_Buffer ? m_Buffer->GetBufferLen () : 0; };
+			void DeleteBuffer () { m_Buffer = nullptr; };
+			std::shared_ptr<Buffer> GetSharedBuffer () const { return m_Buffer; };			
 
 			bool IsUpdated () const { return m_IsUpdated; };
 			void SetUpdated (bool updated) { m_IsUpdated = updated; };
 			bool SaveToFile (const std::string& fullPath);
-
+			static bool SaveToFile (const std::string& fullPath, std::shared_ptr<Buffer> buf);
+		
 			std::shared_ptr<RouterProfile> GetProfile () const;
 			void DropProfile () { m_Profile = nullptr; };
 			bool HasProfile () const { return (bool)m_Profile; }; 
 
 			bool Update (const uint8_t * buf, size_t len);
-			void DeleteBuffer () { m_Buffer = nullptr; };
 			bool IsNewer (const uint8_t * buf, size_t len) const;
 
 			/** return true if we are in a router family and the signature is valid */
@@ -300,7 +309,7 @@ namespace data
 			RouterInfo ();
 			uint8_t * GetBufferPointer (size_t offset = 0 ) { return m_Buffer->data () + offset; };
 			void UpdateBuffer (const uint8_t * buf, size_t len);
-			void SetBufferLen (size_t len) { m_BufferLen = len; };
+			void SetBufferLen (size_t len) { if (m_Buffer) m_Buffer->SetBufferLen (len); };
 			void RefreshTimestamp ();
 			CompatibleTransports GetReachableTransports () const { return m_ReachableTransports; };
 			void SetReachableTransports (CompatibleTransports transports) { m_ReachableTransports = transports; };
@@ -328,7 +337,6 @@ namespace data
 			FamilyID m_FamilyID;
 			std::shared_ptr<const IdentityEx> m_RouterIdentity;
 			std::shared_ptr<Buffer> m_Buffer;
-			size_t m_BufferLen;
 			uint64_t m_Timestamp; // in milliseconds
 			boost::shared_ptr<Addresses> m_Addresses; // TODO: use std::shared_ptr and std::atomic_store for gcc >= 4.9
 			bool m_IsUpdated, m_IsUnreachable, m_IsFloodfill;