[#10] dialer: Define interface state (up/down) on initialization

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

dialer.go

@@ -151,6 +151,7 @@ func NewDialer(c Config) (Multidialer, error) {
 type iface struct {
 	name  string
 	addrs []netip.Prefix
+	down  bool
 }
 
 func processIface(info Interface) (iface, error) {
@@ -168,7 +169,7 @@ func processIface(info Interface) (iface, error) {
 
 		addrs = append(addrs, p)
 	}
-	return iface{name: info.Name(), addrs: addrs}, nil
+	return iface{name: info.Name(), addrs: addrs, down: info.Down()}, nil
 }
 
 func processSubnet(subnet string, sources []iface) (Subnet, error) {
@@ -185,6 +186,7 @@ func processSubnet(subnet string, sources []iface) (Subnet, error) {
 				ifs = append(ifs, Source{
 					Name:      source.name,
 					LocalAddr: &net.TCPAddr{IP: net.IP(src.AsSlice())},
+					Down:      source.down,
 				})
 			}
 		}

dialer_hostname_test.go

@@ -114,10 +114,12 @@ func testInterfacesV6() ([]Interface, error) {
 type testInterface struct {
 	name  string
 	addrs []net.Addr
+	down  bool
 }
 
 func (i *testInterface) Name() string               { return i.name }
 func (i *testInterface) Addrs() ([]net.Addr, error) { return i.addrs, nil }
+func (i *testInterface) Down() bool                 { return i.down }
 
 type testAddr struct {
 	network string

interface.go

@@ -6,6 +6,7 @@ import "net"
 type Interface interface {
 	Name() string
 	Addrs() ([]net.Addr, error)
+	Down() bool
 }
 
 type netInterface struct {
@@ -20,6 +21,10 @@ func (i *netInterface) Addrs() ([]net.Addr, error) {
 	return i.iface.Addrs()
 }
 
+func (i *netInterface) Down() bool {
+	return i.iface.Flags&net.FlagUp == 0
+}
+
 func systemInterfaces() ([]Interface, error) {
 	ifaces, err := net.Interfaces()
 	if err != nil {