cmd/cli: only list physical interfaces when listing

Since these are the interfaces that ctrld will manipulate anyway.

While at it, also skipping non-working devices on MacOS, by checking
if the device is present in network service order

cmd/cli/cli.go

@@ -764,7 +764,7 @@ func netInterface(ifaceName string) (*net.Interface, error) {
 	if iface == nil {
 		return nil, errors.New("interface not found")
 	}
-	if err := patchNetIfaceName(iface); err != nil {
+	if _, err := patchNetIfaceName(iface); err != nil {
 		return nil, err
 	}
 	return iface, err

cmd/cli/commands.go

@@ -9,7 +9,6 @@ import (
 	"io"
 	"net"
 	"net/http"
-	"net/netip"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -25,7 +24,6 @@ import (
 	"github.com/olekukonko/tablewriter"
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
-	"tailscale.com/net/netmon"
 
 	"github.com/Control-D-Inc/ctrld"
 	"github.com/Control-D-Inc/ctrld/internal/clientinfo"
@@ -903,7 +901,7 @@ func initInterfacesCmd() *cobra.Command {
 		Short: "List network interfaces of the host",
 		Args:  cobra.NoArgs,
 		Run: func(cmd *cobra.Command, args []string) {
-			err := netmon.ForeachInterface(func(i netmon.Interface, prefixes []netip.Prefix) {
+			withEachPhysicalInterfaces("", "", func(i *net.Interface) error {
 				fmt.Printf("Index : %d\n", i.Index)
 				fmt.Printf("Name  : %s\n", i.Name)
 				addrs, _ := i.Addrs()
@@ -914,7 +912,14 @@ func initInterfacesCmd() *cobra.Command {
 					}
 					fmt.Printf("        %v\n", ipaddr)
 				}
-				for i, dns := range currentDNS(i.Interface) {
+				nss, err := currentStaticDNS(i)
+				if err != nil {
+					mainLog.Load().Warn().Err(err).Msg("failed to get DNS")
+				}
+				if len(nss) == 0 {
+					nss = currentDNS(i)
+				}
+				for i, dns := range nss {
 					if i == 0 {
 						fmt.Printf("DNS   : %s\n", dns)
 						continue
@@ -922,10 +927,8 @@ func initInterfacesCmd() *cobra.Command {
 					fmt.Printf("      : %s\n", dns)
 				}
 				println()
+				return nil
 			})
-			if err != nil {
-				mainLog.Load().Error().Msg(err.Error())
-			}
 		},
 	}
 	interfacesCmd := &cobra.Command{

cmd/cli/net_darwin.go

@@ -9,17 +9,19 @@ import (
 	"strings"
 )
 
-func patchNetIfaceName(iface *net.Interface) error {
+func patchNetIfaceName(iface *net.Interface) (bool, error) {
 	b, err := exec.Command("networksetup", "-listnetworkserviceorder").Output()
 	if err != nil {
-		return err
+		return false, err
 	}
 
+	patched := false
 	if name := networkServiceName(iface.Name, bytes.NewReader(b)); name != "" {
 		iface.Name = name
 		mainLog.Load().Debug().Str("network_service", name).Msg("found network service name for interface")
+		patched = true
 	}
-	return nil
+	return patched, nil
 }
 
 func networkServiceName(ifaceName string, r io.Reader) string {

cmd/cli/net_others.go

@@ -4,7 +4,7 @@ package cli
 
 import "net"
 
-func patchNetIfaceName(iface *net.Interface) error { return nil }
+func patchNetIfaceName(iface *net.Interface) (bool, error) { return true, nil }
 
 func validInterface(iface *net.Interface, validIfacesMap map[string]struct{}) bool { return true }
 

cmd/cli/net_windows.go

@@ -13,8 +13,8 @@ import (
 	"github.com/microsoft/wmi/pkg/hardware/network/netadapter"
 )
 
-func patchNetIfaceName(iface *net.Interface) error {
-	return nil
+func patchNetIfaceName(iface *net.Interface) (bool, error) {
+	return true, nil
 }
 
 // validInterface reports whether the *net.Interface is a valid one.

cmd/cli/prog.go

@@ -1119,7 +1119,7 @@ func canBeLocalUpstream(addr string) bool {
 func withEachPhysicalInterfaces(excludeIfaceName, context string, f func(i *net.Interface) error) {
 	validIfacesMap := validInterfacesMap()
 	netmon.ForeachInterface(func(i netmon.Interface, prefixes []netip.Prefix) {
-		// Skip loopback/virtual interface.
+		// Skip loopback/virtual/down interface.
 		if i.IsLoopback() || len(i.HardwareAddr) == 0 {
 			return
 		}
@@ -1128,9 +1128,12 @@ func withEachPhysicalInterfaces(excludeIfaceName, context string, f func(i *net.
 			return
 		}
 		netIface := i.Interface
-		if err := patchNetIfaceName(netIface); err != nil {
+		if patched, err := patchNetIfaceName(netIface); err != nil {
 			mainLog.Load().Debug().Err(err).Msg("failed to patch net interface name")
 			return
+		} else if !patched {
+			// The interface is not functional, skipping.
+			return
 		}
 		// Skip excluded interface.
 		if netIface.Name == excludeIfaceName {