Initialize USB ethernet

config.go

@@ -133,7 +133,7 @@ var defaultConfig = &Config{
 		NatEnable: false,
 	},
 	UsbNetworkConfig: &network.UsbNetworkConfig{
-		IPv4Addr:    "172.16.55.1",
+		IPv4Addr:    "172.16.55.1/24",
 		IPv4Network: "172.16.55.0/24",
 	},
 	DefaultLogLevel: "INFO",
@@ -183,6 +183,10 @@ func LoadConfig() {
 		loadedConfig.NetworkConfig = defaultConfig.NetworkConfig
 	}
 
+	if loadedConfig.UsbNetworkConfig == nil {
+		loadedConfig.UsbNetworkConfig = defaultConfig.UsbNetworkConfig
+	}
+
 	config = &loadedConfig
 
 	logging.GetRootLogger().UpdateLogLevel(config.DefaultLogLevel)

internal/network/config.go

@@ -53,7 +53,7 @@ type NetworkConfig struct {
 }
 
 type UsbNetworkConfig struct {
-	IPv4Addr    string `json:"ipv4_addr,omitempty" validate_type:"ipv4" default:"172.16.55.1" required:"true"`
+	IPv4Addr    string `json:"ipv4_addr,omitempty" validate_type:"ipv4" default:"172.16.55.1/24" required:"true"`
 	IPv4Network string `json:"ipv4_network,omitempty" validate_type:"ipv4" default:"172.16.55.0/24" required:"true"`
 }
 

internal/network/nat.go

@@ -10,6 +10,10 @@ const (
 	procIpv4ForwardPath = "/proc/sys/net/ipv4/ip_forward"
 )
 
+func (s *NetworkInterfaceState) UsbNetworkConfig() *UsbNetworkConfig {
+	return s.usbNetConfig
+}
+
 func (s *NetworkInterfaceState) reconfigureNat(wantNat bool, sourceAddr string) error {
 	scopedLogger := s.l.With().Str("iface", s.interfaceName).Logger()
 

internal/network/netif.go

@@ -26,8 +26,9 @@ type NetworkInterfaceState struct {
 	l         *zerolog.Logger
 	stateLock sync.Mutex
 
-	config     *NetworkConfig
+	config       *NetworkConfig
-	dhcpClient *udhcpc.DHCPClient
+	usbNetConfig *UsbNetworkConfig
+	dhcpClient   *udhcpc.DHCPClient
 
 	defaultHostname string
 	currentHostname string
@@ -85,6 +86,7 @@ func NewNetworkInterfaceState(opts *NetworkInterfaceOptions) (*NetworkInterfaceS
 		},
 		cbConfigChange: opts.OnConfigChange,
 		config:         opts.NetworkConfig,
+		usbNetConfig:   opts.UsbNetworkConfig,
 	}
 
 	// create the dhcp client

internal/usbgadget/ethernet.go

@@ -1,5 +1,9 @@
 package usbgadget
 
+const (
+	usbEthernetDevice = "usb0"
+)
+
 // Ethernet Control Model (ECM)
 var ethernetEcmConfig = gadgetConfigItem{
 	order:      4000,
@@ -43,3 +47,14 @@ var ethernetRndisConfig = gadgetConfigItem{
 		"dev_addr":  "", // MAC address of JetKVM (randomly select)
 	},
 }
+
+func (u *UsbGadget) UsbEthernetEnabled() bool {
+	return u.isGadgetConfigItemEnabled("ecm") ||
+		u.isGadgetConfigItemEnabled("eem") ||
+		u.isGadgetConfigItemEnabled("ncm") ||
+		u.isGadgetConfigItemEnabled("rndis")
+}
+
+func (u *UsbGadget) UsbEthernetDevice() string {
+	return usbEthernetDevice
+}

usb.go

@@ -18,6 +18,11 @@ func initUsbGadget() {
 		usbLogger,
 	)
 
+	err := initUsbEthernet(gadget)
+	if err != nil {
+		usbLogger.Err(err).Msg("Failed to initialize USB Ethernet")
+	}
+
 	go func() {
 		for {
 			checkUSBState()

usb_ethernet.go

@@ -0,0 +1,30 @@
+package kvm
+
+import (
+	"fmt"
+	"os/exec"
+
+	"github.com/jetkvm/kvm/internal/usbgadget"
+)
+
+func initUsbEthernet(gadget *usbgadget.UsbGadget) error {
+	if !gadget.UsbEthernetEnabled() {
+		return nil
+	}
+
+	iface := gadget.UsbEthernetDevice()
+	ipv4addr := networkState.UsbNetworkConfig().IPv4Addr
+
+	scopedLogger := usbLogger.With().Str("iface", iface).Str("ipv4addr", ipv4addr).Logger()
+	scopedLogger.Info().Msg("enabling USB Ethernet")
+
+	if err := exec.Command("ip", "addr", "add", ipv4addr, "dev", iface).Run(); err != nil {
+		return fmt.Errorf("failed to flush table nat: %w", err)
+	}
+
+	if err := exec.Command("ip", "link", "set", "dev", iface, "up").Run(); err != nil {
+		return fmt.Errorf("failed to flush table nat: %w", err)
+	}
+
+	return nil
+}