updated network package to work on android

Author: shadowy-pycoder

arpspoof/arpspoof.go

@@ -200,9 +200,14 @@ func (ar *ARPSpoofer) ARPTable() *ARPTable {
 func NewARPSpoofer(conf *ARPSpoofConfig) (*ARPSpoofer, error) {
 	arpspoofer := &ARPSpoofer{}
 	// determining interface
-	iface, err := network.GetDefaultInterface()
+	var iface *net.Interface
+	var err error
+	iface, err = network.GetDefaultInterface()
 	if err != nil {
-		return nil, err
+		iface, err = network.GetDefaultInterfaceFromRoute()
+		if err != nil {
+			return nil, err
+		}
 	}
 	if conf.Interface != "" {
 		arpspoofer.iface, err = net.InterfaceByName(conf.Interface)
@@ -236,7 +241,10 @@ func NewARPSpoofer(conf *ARPSpoofConfig) (*ARPSpoofer, error) {
 		} else {
 			gwIP, err = network.GetDefaultGatewayIPv4()
 			if err != nil {
-				return nil, fmt.Errorf("failed fetching gateway ip: %w", err)
+				gwIP, err = network.GetDefaultGatewayIPv4FromRoute()
+				if err != nil {
+					return nil, fmt.Errorf("failed fetching gateway ip: %w", err)
+				}
 			}
 		}
 		arpspoofer.gwIP = gwIP

network/network.go

@@ -139,6 +139,21 @@ func GetDefaultInterface() (*net.Interface, error) {
 	return net.InterfaceByName(defaultInterface)
 }
 
+func GetDefaultInterfaceFromRoute() (*net.Interface, error) {
+	cmd := exec.Command("sh", "-c", `ip -4 route get 8.8.8.8 | tr -d '\n'`)
+	routeRaw, err := cmd.Output()
+	if err != nil {
+		return nil, err
+	}
+	routeFields := strings.Fields(string(routeRaw))
+	for i, f := range routeFields {
+		if f == "dev" && i+1 < len(routeFields) && routeFields[i+1] != "tun" {
+			return net.InterfaceByName(routeFields[i+1])
+		}
+	}
+	return nil, fmt.Errorf("failed getting default interface from route")
+}
+
 func GetDefaultGatewayIPv4() (netip.Addr, error) {
 	cmd := exec.Command("sh", "-c", `ip -4 route show 0.0.0.0/0 | awk '{print $3 " " $5}'`)
 	ipdevRaw, err := cmd.Output()
@@ -167,6 +182,22 @@ func GetDefaultGatewayIPv4() (netip.Addr, error) {
 	return netip.Addr{}, fmt.Errorf("gateway IPv4 not found ")
 }
 
+func GetDefaultGatewayIPv4FromRoute() (netip.Addr, error) {
+	cmd := exec.Command("sh", "-c", `ip -4 route get 8.8.8.8 | awk '{print $3}' | tr -d '\n'`)
+	ipstrRaw, err := cmd.Output()
+	if err != nil {
+		return netip.Addr{}, err
+	}
+	ip, err := netip.ParseAddr(string(ipstrRaw))
+	if err != nil {
+		return netip.Addr{}, err
+	}
+	if !ip.IsValid() || !ip.Is4() {
+		return netip.Addr{}, fmt.Errorf("failed getting default gateway from route")
+	}
+	return ip, nil
+}
+
 func GetGatewayIPv4FromInterface(iface string) (netip.Addr, error) {
 	cmd := exec.Command("sh", "-c", fmt.Sprintf("ip -4 route show dev %s", iface))
 	routes, err := cmd.Output()

version.go

@@ -1,3 +1,3 @@
 package mshark
 
-const Version string = "mshark v0.0.14"
+const Version string = "mshark v0.0.15"