ADD EDNS check feature, TCP server bugfix

src/dns_client.h

@@ -17,6 +17,7 @@ typedef enum dns_result_type {
 } dns_result_type;
 
 #define DNSSERVER_FLAG_BLACKLIST_IP (0x1 << 0)
+#define DNSSERVER_FLAG_CHECK_EDNS (0x1 << 1)
 
 int dns_client_init(void);