fixed race condition between local buffer creation and sending it through the transports

libi2pd/NTCP2.cpp

@@ -129,7 +129,8 @@ namespace transport
 		options[1] = 2; // ver
 		htobe16buf (options + 2, paddingLength); // padLen
 		// m3p2Len
-		auto bufLen = i2p::context.GetRouterInfo ().GetBufferLen ();
+		auto riBuffer = i2p::context.CopyRouterInfoBuffer ();
+		auto bufLen = riBuffer->GetBufferLen ();
 		m3p2Len = bufLen + 4 + 16; // (RI header + RI + MAC for now) TODO: implement options
 		htobe16buf (options + 4, m3p2Len);
 		// fill m3p2 payload (RouterInfo block)
@@ -138,7 +139,7 @@ namespace transport
 		m3p2[0] = eNTCP2BlkRouterInfo; // block
 		htobe16buf (m3p2 + 1, bufLen + 1); // flag + RI
 		m3p2[3] = 0; // flag
-		memcpy (m3p2 + 4, i2p::context.GetRouterInfo ().GetBuffer (), bufLen); // TODO: own RI should be protected by mutex
+		memcpy (m3p2 + 4, riBuffer->data (), bufLen); // TODO: eliminate extra copy
 		// 2 bytes reserved
 		htobe32buf (options + 8, (i2p::util::GetMillisecondsSinceEpoch () + 500)/1000); // tsA, rounded to seconds
 		// 4 bytes reserved
@@ -1200,7 +1201,8 @@ namespace transport
 	void NTCP2Session::SendRouterInfo ()
 	{
 		if (!IsEstablished ()) return;
-		auto riLen = i2p::context.GetRouterInfo ().GetBufferLen ();
+		auto riBuffer =  i2p::context.CopyRouterInfoBuffer ();
+		auto riLen = riBuffer->GetBufferLen ();
 		size_t payloadLen = riLen + 3 + 1 + 7; // 3 bytes block header + 1 byte RI flag + 7 bytes DateTime
 		m_NextSendBuffer = new uint8_t[payloadLen + 16 + 2 + 64]; // up to 64 bytes padding
 		// DateTime	block
@@ -1211,7 +1213,7 @@ namespace transport
 		m_NextSendBuffer[9] = eNTCP2BlkRouterInfo;
 		htobe16buf (m_NextSendBuffer + 10, riLen + 1); // size
 		m_NextSendBuffer[12] = 0; // flag
-		memcpy (m_NextSendBuffer + 13, i2p::context.GetRouterInfo ().GetBuffer (), riLen);
+		memcpy (m_NextSendBuffer + 13, riBuffer->data (), riLen); // TODO: eliminate extra copy
 		// padding block
 		auto paddingSize = CreatePaddingBlock (payloadLen, m_NextSendBuffer + 2 + payloadLen, 64);
 		payloadLen += paddingSize;

libi2pd/NetDb.hpp

@@ -119,7 +119,11 @@ namespace data
 			size_t VisitRandomRouterInfos(RouterInfoFilter f, RouterInfoVisitor v, size_t n);
 
 			void ClearRouterInfos () { m_RouterInfos.clear (); };
-			std::shared_ptr<RouterInfo::Buffer> NewRouterInfoBuffer () { return m_RouterInfoBuffersPool.AcquireSharedMt (); };
+			template<typename... TArgs>
+			std::shared_ptr<RouterInfo::Buffer> NewRouterInfoBuffer (TArgs&&... args) 
+			{ 
+				return m_RouterInfoBuffersPool.AcquireSharedMt (std::forward<TArgs>(args)...); 
+			}
 			bool PopulateRouterInfoBuffer (std::shared_ptr<RouterInfo> r);
 			std::shared_ptr<RouterInfo::Address> NewRouterInfoAddress () { return m_RouterInfoAddressesPool.AcquireSharedMt (); };
 			boost::shared_ptr<RouterInfo::Addresses> NewRouterInfoAddresses ()

libi2pd/RouterContext.cpp

@@ -78,6 +78,12 @@ namespace i2p
 		}	
 	}	
 
+	std::shared_ptr<i2p::data::RouterInfo::Buffer> RouterContext::CopyRouterInfoBuffer () const
+	{
+		std::lock_guard<std::mutex> l(m_RouterInfoMutex);
+		return m_RouterInfo.CopyBuffer ();
+	}	
+		
 	void RouterContext::CreateNewRouter ()
 	{
 		m_Keys = i2p::data::PrivateKeys::CreateRandomKeys (i2p::data::SIGNING_KEY_TYPE_EDDSA_SHA512_ED25519,
@@ -246,7 +252,10 @@ namespace i2p
 
 	void RouterContext::UpdateRouterInfo ()
 	{
+		{
+			std::lock_guard<std::mutex> l(m_RouterInfoMutex);
 			m_RouterInfo.CreateBuffer (m_Keys);
+		}
 		m_RouterInfo.SaveToFile (i2p::fs::DataDirPath (ROUTER_INFO));
 		m_LastUpdateTime = i2p::util::GetSecondsSinceEpoch ();
 	}

libi2pd/RouterContext.h

@@ -114,6 +114,7 @@ namespace garlic
 				return std::shared_ptr<i2p::garlic::GarlicDestination> (this,
 					[](i2p::garlic::GarlicDestination *) {});
 			}
+			std::shared_ptr<i2p::data::RouterInfo::Buffer> CopyRouterInfoBuffer () const;
 			
 			const uint8_t * GetNTCP2StaticPublicKey () const { return m_NTCP2Keys ? m_NTCP2Keys->staticPublicKey : nullptr; };
 			const uint8_t * GetNTCP2StaticPrivateKey () const { return m_NTCP2Keys ? m_NTCP2Keys->staticPrivateKey : nullptr; };
@@ -258,6 +259,7 @@ namespace garlic
 			std::unordered_set<i2p::data::IdentHash> m_PublishExcluded;
 			uint32_t m_PublishReplyToken;
 			bool m_IsHiddenMode; // not publish
+			mutable std::mutex m_RouterInfoMutex;
 	};
 
 	extern RouterContext context;

libi2pd/RouterInfo.cpp

@@ -1120,6 +1120,12 @@ namespace data
 		m_Buffer->SetBufferLen (len);
 	}
 
+	std::shared_ptr<RouterInfo::Buffer> RouterInfo::CopyBuffer () const
+	{
+		if (!m_Buffer) return nullptr;
+		return netdb.NewRouterInfoBuffer (*m_Buffer);
+	}	
+		
 	std::shared_ptr<RouterInfo::Buffer> RouterInfo::NewBuffer () const
 	{
 		return netdb.NewRouterInfoBuffer ();

libi2pd/RouterInfo.h

@@ -188,6 +188,7 @@ namespace data
 
 					Buffer () = default;
 					Buffer (const uint8_t * buf, size_t len);
+					Buffer (const Buffer& other): Buffer (other.data (), other.m_BufferLen) {};
 
 					size_t GetBufferLen () const { return m_BufferLen; };
 					void SetBufferLen (size_t len) { m_BufferLen = len; };
@@ -282,6 +283,7 @@ namespace data
 			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; };	
+			std::shared_ptr<Buffer> CopyBuffer () const;
 
 			bool IsUpdated () const { return m_IsUpdated; };
 			void SetUpdated (bool updated) { m_IsUpdated = updated; };

libi2pd/SSU2Session.cpp

@@ -337,7 +337,7 @@ namespace transport
 				{
 					if (!s->IsEstablished ()) return;
 					uint8_t payload[SSU2_MAX_PACKET_SIZE];
-					size_t payloadSize = s->CreateRouterInfoBlock (payload, s->m_MaxPayloadSize - 32, i2p::context.GetSharedRouterInfo ());
+					size_t payloadSize = s->CreateRouterInfoBlock (payload, s->m_MaxPayloadSize - 32, i2p::context.CopyRouterInfoBuffer ());
 					if (payloadSize)
 					{
 						if (payloadSize < s->m_MaxPayloadSize)
@@ -883,12 +883,12 @@ namespace transport
 		// payload
 		size_t maxPayloadSize = m_MaxPayloadSize - 48; // for part 2, 48 is part1
 		uint8_t * payload = m_SentHandshakePacket->payload;
-		size_t payloadSize = CreateRouterInfoBlock (payload, maxPayloadSize, i2p::context.GetSharedRouterInfo ());
+		size_t payloadSize = CreateRouterInfoBlock (payload, maxPayloadSize, i2p::context.CopyRouterInfoBuffer ());
 		if (!payloadSize)
 		{
 			// split by two fragments
 			maxPayloadSize += m_MaxPayloadSize;
-			payloadSize = CreateRouterInfoBlock (payload, maxPayloadSize, i2p::context.GetSharedRouterInfo ());
+			payloadSize = CreateRouterInfoBlock (payload, maxPayloadSize, i2p::context.CopyRouterInfoBuffer ());
 			header.h.flags[0] = 0x02; // frag 0, total fragments 2
 			// TODO: check if we need more fragments
 		}
@@ -2537,19 +2537,25 @@ namespace transport
 
 	size_t SSU2Session::CreateRouterInfoBlock (uint8_t * buf, size_t len, std::shared_ptr<const i2p::data::RouterInfo> r)
 	{
-		if (!r || !r->GetBuffer () || len < 5) return 0;
+		if (!r || len < 5) return 0;
+		return CreateRouterInfoBlock (buf, len, r->GetSharedBuffer ());
+	}
+
+	size_t SSU2Session::CreateRouterInfoBlock (uint8_t * buf, size_t len, std::shared_ptr<const i2p::data::RouterInfo::Buffer> riBuffer)
+	{
+		if (!riBuffer || len < 5) return 0;
 		buf[0] = eSSU2BlkRouterInfo;
-		size_t size = r->GetBufferLen ();
+		size_t size = riBuffer->GetBufferLen ();
 		if (size + 5 < len)
 		{
-			memcpy (buf + 5, r->GetBuffer (), size);
+			memcpy (buf + 5, riBuffer->data (), size);
 			buf[3] = 0; // flag
 		}
 		else
 		{
 			i2p::data::GzipDeflator deflator;
 			deflator.SetCompressionLevel (9);
-			size = deflator.Deflate (r->GetBuffer (), r->GetBufferLen (), buf + 5, len - 5);
+			size = deflator.Deflate (riBuffer->data (), riBuffer->GetBufferLen (), buf + 5, len - 5);
 			if (!size) return 0; // doesn't fit
 			buf[3] = SSU2_ROUTER_INFO_FLAG_GZIP; // flag
 		}
@@ -2558,6 +2564,7 @@ namespace transport
 		return size + 5;
 	}	
 	
+		
 	size_t SSU2Session::CreateAckBlock (uint8_t * buf, size_t len)
 	{
 		if (len < 8) return 0;

libi2pd/SSU2Session.h

@@ -326,6 +326,7 @@ namespace transport
 
 			size_t CreateAddressBlock (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& ep);
 			size_t CreateRouterInfoBlock (uint8_t * buf, size_t len, std::shared_ptr<const i2p::data::RouterInfo> r);
+			size_t CreateRouterInfoBlock (uint8_t * buf, size_t len, std::shared_ptr<const i2p::data::RouterInfo::Buffer> riBuffer);
 			size_t CreateAckBlock (uint8_t * buf, size_t len);
 			size_t CreatePaddingBlock (uint8_t * buf, size_t len, size_t minSize = 0);
 			size_t CreateI2NPBlock (uint8_t * buf, size_t len, std::shared_ptr<I2NPMessage>&& msg);