check local address

daemon/Daemon.cpp

@@ -152,7 +152,8 @@ namespace i2p
 				if (!yggaddress.empty ())
 				{
 					yggaddr = boost::asio::ip::address_v6::from_string (yggaddress);
-					if (yggaddr.is_unspecified () || i2p::util::net::GetMTU (yggaddr) != 0xFFFF) // ygg's MTU is always 65535
+					if (yggaddr.is_unspecified () || !i2p::util::net::IsYggdrasilAddress (yggaddr) || 
+					    !i2p::util::net::IsLocalAddress (yggaddr)) 
 					{
 						LogPrint(eLogWarning, "Daemon: Can't find Yggdrasil address ", yggaddress);
 						ygg = false;

libi2pd/util.cpp

@@ -461,6 +461,17 @@ namespace net
 #endif
 	}
 
+	bool IsLocalAddress (const boost::asio::ip::address& addr)
+	{
+		auto mtu =  // TODO: implement better
+#ifdef _WIN32
+		GetMTUWindows(addr, 0);
+#else
+		GetMTUUnix(addr, 0);
+#endif	
+		return mtu > 0;
+	}	
+	
 	bool IsInReservedRange (const boost::asio::ip::address& host) 
 	{
 		// https://en.wikipedia.org/wiki/Reserved_IP_addresses

libi2pd/util.h

@@ -189,6 +189,7 @@ namespace util
 		int GetMTU (const boost::asio::ip::address& localAddress);
 		const boost::asio::ip::address GetInterfaceAddress (const std::string & ifname, bool ipv6=false);
 		boost::asio::ip::address_v6 GetYggdrasilAddress ();
+		bool IsLocalAddress (const boost::asio::ip::address& addr);
 		bool IsInReservedRange (const boost::asio::ip::address& host);
 		bool IsYggdrasilAddress (const boost::asio::ip::address& addr);
 	}