wip

internal/provider/local_cloudflare.go

@@ -8,7 +8,7 @@ import (
 // NewLocal creates a specialized Local provider that uses Cloudflare as the remote server.
 // (No actual UDP packets will be sent to Cloudflare.)
 func NewLocal() Provider {
-	return protocol.Local{
+	return protocol.LocalAuto{
 		ProviderName: "local",
 		RemoteUDPAddr: map[ipnet.Type]string{
 			// 1.0.0.1 is used in case 1.1.1.1 is hijacked by the router

internal/provider/protocol/local.go → internal/provider/protocol/local_auto.go

@@ -9,11 +9,11 @@ import (
 	"github.com/favonia/cloudflare-ddns/internal/pp"
 )
 
-// Local detects the IP address by pretending to send out an UDP packet
+// LocalAuto detects the IP address by pretending to send out an UDP packet
 // and using the source IP address assigned by the system. In most cases
 // it will detect the IP address of the network interface toward the internet.
 // (No actual UDP packets will be sent out.)
-type Local struct {
+type LocalAuto struct {
 	// Name of the detection protocol.
 	ProviderName string
 
@@ -22,25 +22,23 @@ type Local struct {
 }
 
 // Name of the detection protocol.
-func (p Local) Name() string {
+func (p LocalAuto) Name() string {
 	return p.ProviderName
 }
 
 // GetIP detects the IP address by pretending to send an UDP packet.
 // (No actual UDP packets will be sent out.)
-func (p Local) GetIP(_ context.Context, ppfmt pp.PP, ipNet ipnet.Type) (netip.Addr, Method, bool) {
-	var invalidIP netip.Addr
-
+func (p LocalAuto) GetIP(_ context.Context, ppfmt pp.PP, ipNet ipnet.Type) (netip.Addr, Method, bool) {
 	remoteUDPAddr, found := p.RemoteUDPAddr[ipNet]
 	if !found {
 		ppfmt.Noticef(pp.EmojiImpossible, "Unhandled IP network: %s", ipNet.Describe())
-		return invalidIP, MethodUnspecified, false
+		return netip.Addr{}, MethodUnspecified, false
 	}
 
 	conn, err := net.Dial(ipNet.UDPNetwork(), remoteUDPAddr)
 	if err != nil {
 		ppfmt.Noticef(pp.EmojiError, "Failed to detect a local %s address: %v", ipNet.Describe(), err)
-		return invalidIP, MethodUnspecified, false
+		return netip.Addr{}, MethodUnspecified, false
 	}
 	defer conn.Close()
 

internal/provider/protocol/local_test.go → internal/provider/protocol/local_auto_test.go

@@ -17,7 +17,7 @@ import (
 func TestLocalName(t *testing.T) {
 	t.Parallel()
 
-	p := &protocol.Local{
+	p := &protocol.LocalAuto{
 		ProviderName:  "very secret name",
 		RemoteUDPAddr: nil,
 	}
@@ -102,7 +102,7 @@ func TestLocalGetIP(t *testing.T) {
 			t.Parallel()
 			mockCtrl := gomock.NewController(t)
 
-			provider := &protocol.Local{
+			provider := &protocol.LocalAuto{
 				ProviderName: "",
 				RemoteUDPAddr: map[ipnet.Type]string{
 					tc.addrKey: tc.addr,

internal/provider/protocol/local_iface.go

@@ -0,0 +1,55 @@
+package protocol
+
+import (
+	"context"
+	"net"
+	"net/netip"
+
+	"github.com/favonia/cloudflare-ddns/internal/ipnet"
+	"github.com/favonia/cloudflare-ddns/internal/pp"
+)
+
+// LocalWithInterface detects the IP address by choosing the first "good" IP
+// address assigned to a network interface.
+type LocalWithInterface struct {
+	// Name of the detection protocol.
+	ProviderName string
+
+	// The name of the network interface
+	InterfaceName string
+}
+
+// Name of the detection protocol.
+func (p LocalWithInterface) Name() string {
+	return p.ProviderName
+}
+
+// GetIP detects the IP address by pretending to send an UDP packet.
+// (No actual UDP packets will be sent out.)
+func (p LocalWithInterface) GetIP(_ context.Context, ppfmt pp.PP, ipNet ipnet.Type) (netip.Addr, Method, bool) {
+	iface, err := net.InterfaceByName(p.InterfaceName)
+	if err != nil {
+		ppfmt.Noticef(pp.EmojiUserError, "Failed to find an interface named %q: %v", p.InterfaceName, err)
+		return netip.Addr{}, MethodUnspecified, false
+	}
+
+	addrs, err := iface.Addrs()
+	if err != nil {
+		ppfmt.Noticef(pp.EmojiUserError, "Failed to list addresses of %q: %v", p.InterfaceName, err)
+		return netip.Addr{}, MethodUnspecified, false
+	}
+
+	for _, addr := range addrs {
+		ip, err := netip.ParseAddr(addr.String())
+		if err != nil {
+			ppfmt.Noticef(pp.EmojiUserError, "Failed to parse address %q of %q: %v", addr.String(), p.InterfaceName, err)
+			return netip.Addr{}, MethodUnspecified, false
+		}
+
+		if ipNet.Matches(ip) && ip.IsGlobalUnicast() {
+			return ip, MethodUnspecified, true
+		}
+	}
+
+	return netip.Addr{}, MethodUnspecified, false
+}