correct buffer size for deflate

Streaming.cpp

@@ -764,6 +764,7 @@ namespace stream
 			m_LocalDestination.m_Deflator.SetCompressionLevel (Z_DEFAULT_COMPRESSION);
 		uint8_t * buf = msg->GetPayload ();
 		buf += 4; // reserve for lengthlength
+		msg->len += 4;
 		size_t size = m_LocalDestination.m_Deflator.Deflate (payload, len, buf, msg->maxLen - msg->len);
 		if (size)
 		{
@@ -771,7 +772,7 @@ namespace stream
 			htobe16buf (buf + 4, m_LocalDestination.GetLocalPort ()); // source port
 			htobe16buf (buf + 6, m_Port); // destination port 
 			buf[9] = i2p::client::PROTOCOL_TYPE_STREAMING; // streaming protocol
-			msg->len += size + 4; 
+			msg->len += size; 
 			msg->FillI2NPMessageHeader (eI2NPData);
 		}	
 		else