check message length

libi2pd_client/I2CP.cpp

@@ -245,10 +245,18 @@ namespace client
 		{
 			m_PayloadLen = bufbe32toh (m_Header + I2CP_HEADER_LENGTH_OFFSET);
 			if (m_PayloadLen > 0)
+			{
+				if (m_PayloadLen <= I2CP_MAX_MESSAGE_LENGTH)
 				{	
 					m_Payload = new uint8_t[m_PayloadLen];
 					ReceivePayload ();
 				}
+				else
+				{
+					LogPrint (eLogError, "I2CP: Unexpected payload length ", m_PayloadLen); 
+					Terminate ();
+				}	
+			}
 			else // no following payload
 			{
 				HandleMessage ();

libi2pd_client/I2CP.h

@@ -24,6 +24,7 @@ namespace client
 {
 	const uint8_t I2CP_PROTOCOL_BYTE = 0x2A;
 	const size_t I2CP_SESSION_BUFFER_SIZE = 4096;
+	const size_t I2CP_MAX_MESSAGE_LENGTH = 65535;
 	
 	const size_t I2CP_HEADER_LENGTH_OFFSET = 0;
 	const size_t I2CP_HEADER_TYPE_OFFSET = I2CP_HEADER_LENGTH_OFFSET + 4;