add funcs to add and remove ip from interface

network/interface.go

@@ -167,3 +167,95 @@ func configureLinux(interfaceName string, ip net.IP, ipNet *net.IPNet) error {
 
 	return nil
 }
+
+// AddSecondaryAddress adds an additional IP address (given as CIDR, e.g. "10.10.0.5/32")
+// to an already-configured interface. It also records the address in the shared
+// NetworkSettings (see AddIPv4Address) so mobile (iOS/Android) packet-tunnel providers
+// pick it up on their next settings poll - those platforms have no OS-level interface
+// to configure directly, so this is the only way they learn about the address.
+func AddSecondaryAddress(interfaceName string, addr string) error {
+	ip, ipNet, err := net.ParseCIDR(addr)
+	if err != nil {
+		return fmt.Errorf("invalid IP address: %v", err)
+	}
+
+	mask := net.IP(ipNet.Mask).String()
+	AddIPv4Address(ip.String(), mask)
+
+	if interfaceName == "" {
+		return nil
+	}
+
+	switch runtime.GOOS {
+	case "linux":
+		return configureLinux(interfaceName, ip, ipNet)
+	case "darwin":
+		return configureDarwin(interfaceName, ip, ipNet)
+	case "windows":
+		return configureWindows(interfaceName, ip, ipNet)
+	default:
+		return nil
+	}
+}
+
+// RemoveSecondaryAddress removes an IP address (given as CIDR) previously added with
+// AddSecondaryAddress, including from the shared NetworkSettings used by mobile
+// packet-tunnel providers.
+func RemoveSecondaryAddress(interfaceName string, addr string) error {
+	ip, ipNet, err := net.ParseCIDR(addr)
+	if err != nil {
+		return fmt.Errorf("invalid IP address: %v", err)
+	}
+
+	RemoveIPv4Address(ip.String())
+
+	if interfaceName == "" {
+		return nil
+	}
+
+	switch runtime.GOOS {
+	case "linux":
+		return removeLinuxAddress(interfaceName, ip, ipNet)
+	case "darwin":
+		return removeDarwinAddress(interfaceName, ip, ipNet)
+	case "windows":
+		return removeWindowsAddress(interfaceName, ip, ipNet)
+	default:
+		return nil
+	}
+}
+
+func removeLinuxAddress(interfaceName string, ip net.IP, ipNet *net.IPNet) error {
+	link, err := netlink.LinkByName(interfaceName)
+	if err != nil {
+		return fmt.Errorf("failed to get interface %s: %v", interfaceName, err)
+	}
+
+	addr := &netlink.Addr{
+		IPNet: &net.IPNet{
+			IP:   ip,
+			Mask: ipNet.Mask,
+		},
+	}
+
+	if err := netlink.AddrDel(link, addr); err != nil {
+		return fmt.Errorf("failed to remove IP address: %v", err)
+	}
+
+	return nil
+}
+
+func removeDarwinAddress(interfaceName string, ip net.IP, ipNet *net.IPNet) error {
+	prefix, _ := ipNet.Mask.Size()
+	ipStr := fmt.Sprintf("%s/%d", ip.String(), prefix)
+
+	cmd := exec.Command("/sbin/ifconfig", interfaceName, "inet", ipStr, "-alias")
+	logger.Info("Running command: %v", cmd)
+
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("ifconfig command failed: %v, output: %s", err, out)
+	}
+
+	return nil
+}

network/interface_notwindows.go

@@ -10,3 +10,7 @@ import (
 func configureWindows(interfaceName string, ip net.IP, ipNet *net.IPNet) error {
 	return fmt.Errorf("configureWindows called on non-Windows platform")
 }
+
+func removeWindowsAddress(interfaceName string, ip net.IP, ipNet *net.IPNet) error {
+	return fmt.Errorf("removeWindowsAddress called on non-Windows platform")
+}

network/interface_windows.go

@@ -61,3 +61,35 @@ func configureWindows(interfaceName string, ip net.IP, ipNet *net.IPNet) error {
 
 	return nil
 }
+
+func removeWindowsAddress(interfaceName string, ip net.IP, ipNet *net.IPNet) error {
+	iface, err := net.InterfaceByName(interfaceName)
+	if err != nil {
+		return fmt.Errorf("failed to get interface %s: %v", interfaceName, err)
+	}
+
+	luid, err := winipcfg.LUIDFromIndex(uint32(iface.Index))
+	if err != nil {
+		return fmt.Errorf("failed to get LUID for interface %s: %v", interfaceName, err)
+	}
+
+	maskBits, _ := ipNet.Mask.Size()
+
+	var addr netip.Addr
+	if ip4 := ip.To4(); ip4 != nil {
+		addr, _ = netip.AddrFromSlice(ip4)
+	} else {
+		addr, _ = netip.AddrFromSlice(ip)
+	}
+	if !addr.IsValid() {
+		return fmt.Errorf("failed to convert IP address")
+	}
+	prefix := netip.PrefixFrom(addr, maskBits)
+
+	logger.Info("Removing IP address %s from interface %s", prefix.String(), interfaceName)
+	if err := luid.DeleteIPAddress(prefix); err != nil {
+		return fmt.Errorf("failed to remove IP address: %v", err)
+	}
+
+	return nil
+}

network/settings.go

@@ -81,6 +81,45 @@ func SetIPv4Settings(addresses []string, subnetMasks []string) {
 	logger.Info("Set IPv4 addresses: %v, subnet masks: %v", addresses, subnetMasks)
 }
 
+// AddIPv4Address appends an additional IPv4 address/subnet mask pair to the
+// tunnel's network settings. This is how a secondary interface address gets
+// exposed to mobile (iOS/Android) packet-tunnel providers, which read the
+// full IPv4Addresses/IPv4SubnetMasks arrays (not just the first entry) and
+// re-apply them on every settings poll.
+func AddIPv4Address(address string, subnetMask string) {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+
+	for _, a := range networkSettings.IPv4Addresses {
+		if a == address {
+			logger.Info("IPv4 address already exists: %s", address)
+			return
+		}
+	}
+
+	networkSettings.IPv4Addresses = append(networkSettings.IPv4Addresses, address)
+	networkSettings.IPv4SubnetMasks = append(networkSettings.IPv4SubnetMasks, subnetMask)
+	incrementor++
+	logger.Info("Added IPv4 address: %s/%s", address, subnetMask)
+}
+
+// RemoveIPv4Address removes a previously added secondary IPv4 address.
+func RemoveIPv4Address(address string) {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+
+	for i, a := range networkSettings.IPv4Addresses {
+		if a == address {
+			networkSettings.IPv4Addresses = append(networkSettings.IPv4Addresses[:i], networkSettings.IPv4Addresses[i+1:]...)
+			networkSettings.IPv4SubnetMasks = append(networkSettings.IPv4SubnetMasks[:i], networkSettings.IPv4SubnetMasks[i+1:]...)
+			incrementor++
+			logger.Info("Removed IPv4 address: %s", address)
+			return
+		}
+	}
+	logger.Info("IPv4 address not found for removal: %s", address)
+}
+
 // SetIPv4IncludedRoutes sets the included IPv4 routes
 func SetIPv4IncludedRoutes(routes []IPv4Route) {
 	networkSettingsMutex.Lock()