chore: ignore interfaces not in IfOperStatusUp when fetch system dns server on windows

Author: wwqgtxx

dns/system_windows.go

@@ -19,6 +19,16 @@ func dnsReadConfig() (servers []string, err error) {
 		return
 	}
 	for _, aa := range aas {
+		// Only take interfaces whose OperStatus is IfOperStatusUp(0x01) into DNS configs.
+		if aa.OperStatus != windows.IfOperStatusUp {
+			continue
+		}
+
+		// Only take interfaces which have at least one gateway
+		if aa.FirstGatewayAddress == nil {
+			continue
+		}
+
 		for dns := aa.FirstDnsServerAddress; dns != nil; dns = dns.Next {
 			sa, err := dns.Address.Sockaddr.Sockaddr()
 			if err != nil {
@@ -63,7 +73,8 @@ func adapterAddresses() ([]*windows.IpAdapterAddresses, error) {
 	l := uint32(15000) // recommended initial size
 	for {
 		b = make([]byte, l)
-		err := windows.GetAdaptersAddresses(syscall.AF_UNSPEC, windows.GAA_FLAG_INCLUDE_PREFIX, 0, (*windows.IpAdapterAddresses)(unsafe.Pointer(&b[0])), &l)
+		const flags = windows.GAA_FLAG_INCLUDE_PREFIX | windows.GAA_FLAG_INCLUDE_GATEWAYS
+		err := windows.GetAdaptersAddresses(syscall.AF_UNSPEC, flags, 0, (*windows.IpAdapterAddresses)(unsafe.Pointer(&b[0])), &l)
 		if err == nil {
 			if l == 0 {
 				return nil, nil